Can birds pass diseases to humans through contact surfaces?

Can birds pass diseases to humans through contact surfaces?

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My friend asked me the following question. She has a pigeon nesting on her window and the pigeon often touches the window, and my friend also sometimes touches the window (e.g. open and close it). The question is does the touching of her and the pigeon in a common surface (the window) can transmit infections or disease from the pigeon to herself? Is there a risk letting the pigeon nest on her window pane?

Provided she washes her hands after touching surfaces that came into direct contact with the pigeon, there shouldn't be any relevant health risks from touching this surface.

And just because it sound like the pigeon somehow is nesting WITHIN her apartment: Be aware that pigeons can carry mites that could spread within the apartment and infest plants. I would advise against having wild pigeons in the apartment!


Knowing the pigeon is outside, it's not 100% necessary to remove the nest. It depends on whether this window is used for venting and on the direction of air pressure. (does wind go in or out at this side of the house?). Also it depends on the visual cleanliness of the nest. Bird-droppings can potentially represent a health risk, as they can spread through the air, once they dry out, while potentially containing dangerous micro-organisms. Same with feathers that lie around.

So if wind regularly comes from the side of the nest, she could remove the nest for safety reasons, especially if the window is in the kitchen. Otherwise she can't overcome that guilt by blaming health.

What are zoonotic diseases?

Zoonotic diseases, also called zoonoses, are illnesses caused by germs that are passed between animals and people.

"Put simply, a zoonotic disease is one that originates in animals and can cause disease in humans," said Barbara Han, a disease ecologist at the Cary Institute of Ecosystem Studies in New York.

Zoonotic diseases are prevalent throughout the world they can be caused by viruses, bacteria, parasites or fungi, and may cause mild or severe illness or death. Experts estimate that about 60% of known infectious diseases in people can be spread by animals, and 3 out of every 4 new diseases in people originated in animals, according to the Centers for Disease Control and Prevention (CDC).

Q: Are there ways to observe and help birds other than feeders?

A: Naturescaping involves planting native plants and installing wildlife-friendly landscape features that provide shelter, food and water for a variety of species. Rather than providing supplemental food like a bird feeder, naturescaping provides animals with needed habitat. WDFW’s Habitat at Home program has lots of information on how to make your property more wildlife friendly, even if it is a small area, or the PAWS (Progressive Animal Welfare Society) resource library has more information on naturescaping and planting native plants.

Q. Can hummingbirds catch salmonellosis? Should I take down hummingbird feeders as well?

A. While the risk of salmonella transmission is much lower with the design of hummingbird feeders, there is still some risk. To be as safe as possible and reduce the risk as much as possible, it would be best to take them down as well.

Q. Do I need to discontinue broadcast or scatter feeding of wild birds as well?

A. Yes, any activity that promotes a concentration of birds in one area should be discontinued for the time being.

Q. How long until I can put my bird feeders back up again?

A. WDFW reassessed the situation in late February and determined that reports of dead and sick birds were still coming in to the department. Based on this, it was decided to recommend that members of the public leave their bird feeders down until April 1, in both Eastern and Western Washington.

Q. Can salmonellosis transfer to humans?

A. It is possible, although uncommon, for salmonella bacteria to transfer from birds to humans through direct contact with infected birds, droppings, or through domestic cats that encounter sick or dead birds. When handling birds, bird feeders, bird droppings, or bird baths, wear gloves and wash hands thoroughly afterward.

Q. Can salmonellosis transfer to other animals?

A. Dogs, cats, raccoons, raptors and other animals can definitely become infected with salmonella, but actual reports of it happening are quite rare. Regardless, to reduce risk as much as possible, clean up (see how in question above) spilled seed and carcasses, and don’t let cats and dogs eat carcasses. Poultry are also susceptible to salmonella. Because WDFW’s purview isn’t domestic animals, you may want to contact the Washington Department of Agriculture or the WSU Extension office for information on how to keep chickens and other domestic fowl safe. Generally though the best idea is to keep their area clean and keep them away from wild bird feeding sites.

Q. How should I dispose of dead birds that I find?

A. To prevent the spread of salmonellosis, please wear gloves when handling dead or sick birds and put them into a plastic bag, seal or tie, and put in the trash. You can also double up plastic bags, put them over your hand, pick up the bird, then turn the bag inside out over the bird and seal or tie

WDFW recently partnered with the Seattle chapter of the Audubon Society for a virtual presentation and question and answer session on this topic. Watch it below.

Suggested Articles

Although most feline infectious diseases only affect cats, some of these diseases can be transmitted from cats to people. Diseases that can be transmitted from animals to people are called zoonotic diseases. While not comprehensive, this article highlights the most common zoonotic diseases that may be carried by cats and simple precautions you can take to reduce your risk of contracting these diseases. For more information about specific risks, diagnosis, and treatment of zoonotic diseases, contact your physician/health professional.

The likelihood of an average person contracting a zoonotic disease from a cat is low, but individuals with immature or weakened immune systems are more susceptible to these diseases. This includes infants, individuals with acquired immunodeficiency syndrome (AIDS), the elderly, and people undergoing cancer chemotherapy or receiving other drugs that may suppress their immune systems.


Bacterial Infections
Cat scratch disease (CSD) is caused by a bacterium called Bartonella henselae, which may be carried in the saliva of infected cats and in the bodies of cat fleas. As the name implies, this bacterial infection is usually transmitted from cat to human via scratches, although it can also be transmitted via bite wounds and when a cat licks the open wounds of a person. Among cats, this bacterium is most commonly transmitted by the bites of infected cat fleas, and it may also be found in the feces of these fleas, which can serve as sources of infection if exposed to an open wound in either a cat or a human.

People with CSD usually develop swelling and possibly a blister at the site of the bite or scratch. Lymph nodes in the region of the wound may swell and become painful, and affected individuals may experience fever, headache, sore muscles and joints, fatigue, and poor appetite. Healthy adults generally recover with no lasting effects, but it may take several months for the disease to go away completely. People with compromised immune systems may suffer more severe consequences, including infections of the eyes, brain, and heart. Severe cases of CSD may require antibiotic therapy to resolve.

Approximately 40 percent of cats are infected with Bartonella henselae, but most show no signs of disease. Antibiotics do not reliably cure infection in these cats and are not currently recommended. For humans, avoiding scratches and bites (for example, by not allowing children to play roughly with cats), washing hands after playing with cats, controlling fleas, and keeping cats indoors all reduce the risk of CSD. Because most cases of CSD result from contact with kittens under one year of age, immunocompromised people should avoid such contact.

Pasteurella multocida is a bacterium found in the mouths of between 70 and 90 percent of cats, and it has been found in between 50 and 80 percent of cat bites in humans that become serious enough to seek medical attention. Cat bites infected with this organism may develop pain, swelling, and redness at the wound site within 24 to 48 hours. Pasteurella-infected cat bite wounds are successfully treated with antibiotic therapy in the vast majority of cases, but more serious complications, such as the spread of bacteria through the blood stream and infection of heart valves, may occur in rare cases.

Salmonella poisoning, also called salmonellosis, is caused by a group of bacteria called Salmonella, and can lead to diarrhea, fever, and stomach pain beginning one to three days after infection. People usually contract salmonellosis by eating contaminated food, such as undercooked chicken or eggs, but it is possible to contract the disease from infected cats, which can carry Salmonella bacteria and pass them in their stool. Although salmonellosis usually resolves on its own, some individuals require medical attention to address severe diarrhea or the effects of the infection on organs other than the digestive tract.

Salmonella is more commonly found in cats that feed on raw meat or wild birds and animals, so owners can reduce the risk of salmonellosis in themselves and their cats by keeping cats indoors and feeding them cooked or commercially processed food. Wearing gloves when cleaning litterboxes or gardening (in case outdoor cats have defecated in the soil) and washing hands thoroughly after these activities is also recommended.

Parasitic Infections
Fleas are the most common external parasite of cats, and their bites can cause itching and inflammation in humans and cats alike. Fleas may also serve as vectors for CSD and other zoonotic diseases. Flea-infested cats may become infected with tapeworms from fleas ingested while grooming. While not common, people can also become infected with tapeworms by inadvertently ingesting fleas.

Scabies, or infection by the mange mite Sarcoptes scabiei, is another zoonotic external parasite of the skin of cats. While not as common as flea infestations, these mites can be passed from infected cats to people, where they burrow into the skin and cause itchy, raised lesions. Treatment in people usually involves the use of topical ointments to decrease itching, diligent treatment of infective pets, and careful cleaning of clothes and bedding.

Certain feline intestinal parasites, including roundworms (Toxocara) and hookworms (Ancylostoma), can also cause disease in people. Children are particularly at risk due to their higher likelihood of contact with soil that has been contaminated by cat feces. Although most people infected with feline intestinal parasites do not show signs of illness, some people may get sick.

Visceral larva migrans, a potentially serious disease that can affect various organs, results from consumption of Toxocara eggs (for instance, when soiled fingers are placed in the mouth). Toxocara larvae may then migrate to abdominal organs, including the liver, or to the central nervous system. Symptoms of visceral larva migrans may include fever, fatigue, coughing, wheezing, and abdominal pain. Ocular larva migrans is the term used for a condition in which Toxocara larvae migrate to the eye, causing visual disturbances, abnormal eye movements, or eye pain and discomfort.

Cutaneous larva migrans, an itchy skin disease, is caused by contact with soil contaminated with Ancylostoma larvae. These larvae may penetrate and migrate under the skin, with resultant inflammation, itching and pain, and raised, red linear lesions in the skin that follow the larva’s migration. Proper hygiene, including washing hands before meals, cleaning soil from vegetables, and reducing exposure to cat feces can prevent infection. Anti-parasite medications for kittens and annual fecal exams for adult cats can reduce environmental contamination and the risk of human infection.

Fungal Infections
Ringworm (or dermatophytosis) is not caused by a worm at all. Rather, it is a skin infection caused by a group of fungi. Infected cats most often come from environments housing large numbers of animals. In cats, ringworm usually appears as a dry, gray, scaly patch on the skin. In humans, ringworm often appears as a round, red, itchy lesion with a ring of scale around the edge. Lesions may be found in a variety of places, including the scalp, the feet (where’s its referred to as “athlete’s foot”), the groin, or the beard. Ringworm is transmitted by contact with an infected animal’s skin or fur, either directly or from a contaminated environment. Infected cats continuously drop fungal spores from their skin and fur. These spores, which remain capable of causing infection for many months, are difficult to eradicate from a household. Children are particularly at risk of infection. Treatment involves the use of either topical antifungal ointments or oral antifungal medication, depending upon the severity and location of lesions. To reduce environmental contamination, confine infected cats to one room until they are free of infection, then thoroughly clean and disinfect the household.

Protozoal Infections
Protozoans are single-celled organisms. The three most common protozoal diseases in cats and humans are cryptosporidiosis, giardiasis, and toxoplasmosis.

Cryptosporidiosis can cause diarrhea, vomiting, fever, abdominal cramps, and dehydration in both cats and people. Either direct or indirect contact with the feces of cats infected with Cryptosporidium organisms can lead to transmission of this disease. As with most other zoonotic diseases, immunocompromised individuals are at the greatest risk of infection. To prevent the spread of infection, schedule annual fecal examinations for your cats, and medicate infected cats as directed by your veterinarian. Other preventive measures include wearing gloves while handling feces-contaminated material and washing hands afterwards.

Giardiasis is caused by infection with the microscopic parasite Giardia. Many animal species (including the cat), are susceptible to infection with Giardia, which is passed in the feces and usually spread to other animals and humans via contaminated water sources, surfaces, or in uncooked food items. The symptoms of Giardia infection include diarrhea, flatulence, abdominal cramps, nausea, and dehydration. A number of prescription drugs are available to treat this condition, and most people that are infected make an uneventful recovery. It is important to realize that the majority of cases of giardiasis in people do not occur as a result of infection by cats, but rather by ingesting water or food contaminated by farm animals or wildlife.

Toxoplasmosis is caused by the parasitic protozoan Toxoplasma gondii. People with weakened immune systems and infants whose mothers are infected during pregnancy can develop severe illness from this parasite. Most people infected with Toxoplasma, however, show no overt signs of disease.

Cats can acquire Toxoplasma by eating infected rodents, birds, or anything contaminated with feces from another infected animal. An infected cat can shed the parasite in its feces for up to two weeks. Once shed in the feces, the parasite must mature for one to five days before it becomes capable of causing infection. However, it can persist in the environment for many months and continue to contaminate soil, water, gardens, sandboxes, or any place where an infected cat has defecated. Although pregnant women or immunosuppressed individuals are often advised to remove cats from the household to reduce the risk of toxoplasmosis, direct contact with cats is very unlikely to spread infection with this organism.

Cats can transmit Toxoplasma to people through their feces, but humans most commonly become infected by eating undercooked or raw meat, or by inadvertently consuming contaminated soil on unwashed or undercooked vegetables. The symptoms of toxoplasmosis include flu-like muscle aches and fever, and headache. In rare cases, more advanced symptoms such as confusion, seizures, vomiting, or diarrhea may be observed.

Basic hygiene can prevent the spread of Toxoplasma from cats to humans. Wear gloves when handling potentially contaminated material (for example, when gardening or scooping the litterbox), and be sure to wash your hands afterwards. Cover children’s sandboxes when not in use to prevent wandering cats from defecating in them.

Pregnant women or immunosuppressed individuals are safest when other household members clean the litter box.

Viral Infections
Rabies is a viral disease that is spread through the bite of an infected animal. Although most viruses infect only their natural host species, rabies is an important exception. Cats are highly susceptible to rabies, which attacks the central nervous system, causing a variety of signs. Rabies is almost always fatal. In people, rabies infections usually occur when an infected animal bites a person. In order to protect human health, rabies vaccination of cats is required by law in many areas. Even if your cat is kept indoors, it is important to keep rabies vaccines current because cats occasionally escape outdoors, and because rabid animals such as bats and raccoons occasionally enter houses. To further reduce your risk of rabies, avoid contact with wildlife and stray animals and see a doctor immediately if you have been bitten by an animal.

Avian pox

Avian pox is a viral skin infection that shows up as warty growths on the head (particularly next to the eyes and beak), legs, wings or other body parts of the infected bird.

The growths are usually grey, pinkish, red or yellow in colour, and can reach a considerable size. Smaller brown or grey lesions can be confused with ticks. Affected birds feed and move around normally. The birds most often affected are tits, dunnocks and pigeons.

Avian poxvirus spreads between birds by biting insects, by direct bird-to-bird contact, and by indirect contact via contaminated surfaces such as perches or bird feeders. The virus is relatively resistant and can persist on contaminated surfaces for long periods of time.

Where an avian poxvirus outbreak exists, ensure optimal hygiene at garden bird feeding stations, paying particular attention to regular disinfection of surfaces that the affected birds have been in contact with, such as perches or feeder ports. Clean out bird baths on a daily basis, and refill with fresh water.

If a large number of affected birds congregate, consider reducing the amount you feed while affected birds visit the garden to help reduce close contact between them and healthy birds.


It is estimated that over 60% of the western families own a pet. The majority of these households keep a dog. Dogs have been kept as pets for over 14 centuries. Many studies have confirmed the precious roles of pets in the human life. Evidence has shown that owning a pet can increase the activity of pet owners and consequently reduced serum cholesterol, low triglyceride levels, and fewer cardiovascular events [1,2]. Also, some other studies demonstrated that pet owners suffer from depression and mental stress less and have a higher self esteem compared to others. Although dogs have several positive effects on the psychosocial and psychical health of their owners, many diseases among humans are attributed to them [3]. Children and immunocompromised individuals are especially at an increased risk of developing zoonoses infections. Several studies demonstrated that domestic dogs have a dramatic role in developing zoonoses disease and hospitalization [4,5].

Regarding domestic dogs, the increase in the population of stray and semi domestic dogs in urban areas has increased the risk of zoonoses diseases. About 5 million people throughout the world are annually bitten by dogs. Many parasitic and zoonotic pathogens are transmitted by dogs [6,7]. This review focused on the most important viral and bacterial zoonotic diseases, which can be transmitted by dogs.

Rabies is a single strand RNA virus belonging to the Rhabdoviridae family. Rabies infection is an ancient disease with a high mortality rate in human and animal population. Based on the World Health Organization reports, annually between 30000 and 70000 deaths occurred throughout the world due to rabies infection [8]. Dogs are the major animal reservoirs for rabies infection. The majority of the infected patients in developing countries are infected by dog bites while, in developed countries, wild animals including raccoons, bats and foxes are the main cause for rabies transmission [9]. In a study in the United States, a rabies control program was conducted by using extensive vaccination in domestic dogs and reducing the rabies infection [8]. The incubation period for rabies varies between 4 days to several years depending on the location of the inoculating wound and the amount of induced viruses. Patients may present agitation, anxiety, confusion, hallucination, and hydrophobia. Post exposure prophylaxis with frequent doses of human rabies immunoglobulin (HRIG) within 14 days after the suspected dog bite can prevent the disease. Washing the wound with water and liquid soap can dramatically reduce the viral lead and consequently the probability of rabies infection [10].


Noroviruses are a heterogeneous single strand RNA virus belonging to the Caliciviridae family. Noroviruses are the main cause of sporadic and epidemic gastroenteritis in humans [11]. This virus can affect humans of all ages. The virus can be found in the gastrointestinal tract and consequently in the feces or diarrhea of the infected dogs. It can be transmitted from contaminated food or water to humans and the infection can rapidly spread in the human population by fecal oral rate. Serum therapy should be considered for patients with acute gastroenteritis [12].


Pasteurella species are Gram-negative coccobacilli, which were primarily found in animals. Pasteurella spp are normal flora of the upper respiratory tract of dogs and cats. Pasteurella infection can be transmitted to humans by direct and indirect contact such as dog or cat bites or licks and even cat scratches [6]. Several infectious diseases in humans are attributed to Pasteurella spp. The soft tissue infection is the most important infection transmitted by Pasteurella spp. However, meningitis, bone and joint infections and respiratory infection can be transmitted by Pasteurella spp [13]. In a prospective study in United States, the author demonstrated that Pasteurella spp. was the most frequent organism isolated from dog and cat bites [2]. Pasteurella infection can be treated by second and third generation cephalosporin, macrolides, fluoroquinolones, cotrimoxazole, and penicillin [14].

Salmonella species are anaerobic and motile gram-negative bacilli that colonize in the large intestine of a variety of mammals, especially in the distal part of the colon and the mesenteric lymph nodes of the canine. Humans can also get infected through the gastrointestinal tract [fecal transmission] and develop several infectious diseases such as gastroenteritis, enteric fever, bacteremia and osteomyelitis. Gastrointestinal diseases are the most prevalent clinical presentations of salmonella in human and dogs however, the majority of infected animals or humans is asymptomatic and may shed the pathogen through feces for a period of 6 weeks and transmit the pathogen to other animals or individuals. In developing nations, Salmonella spp. is also more prevalent than in developed countries [15,16]. An antibiogram should be considered for patients infected with Salmonella spp. however, it could be treated by various families of antibiotics including fluoroquinolones, beta-lactams, and macrolides [17].

Brucellosis is one of the most prevalent zoonoses, which imposes a heavy burden on the national health services. It is commonly transmitted to humans by consuming unpasteurized dairy products. Various types of brucella spp. have been recognized that resulted in human brucellosis such as B. melitensis, B. abortus and B. suis but, B. canis has been less known as an usual pathogen in brucellosis infection in humans [18,19]. Although B. canis is not responsible for the brucellosis infection in humans, the reported cases were more often seen among farmer populations who had a history of exposure to body fluids of dogs, which were infected with B. canis. The incubation period may last for one to four weeks up to several months [19]. The patients may be asymptomatic or may even present serious clinical symptoms especially fever, night sweats and low back pain in the endemic region that should be differentiated from tuberculosis and other malignancies [20]. Brucellosis should be treated in order to avoid complications and sequelae of the disease. Combination therapies, which are widely employed in the treatment of brucellosis, consisted of doxycycline plus streptomycin or rifampin for 6 weeks [21].

Yersinia enterocolitica

Y. enterocolitica is a gram-negative coccobacillus zoonotic pathogen that causes yersiniosis in human and animals. Several animals are main reservoirs for Y. enterocolitica including birds, pigs, deer, and cattle. The pathogen has been isolated from dog bite wound in some studies [22]. The patients may be asymptomatic in early stage and when the pathogen invades the mucosal surface of the intestine, watery or bloody diarrhea may be present. The pathogen can also involve the peyer’s patches and represent the appendicitis symptoms [23,24]. Y. enterocolitica is mostly a self-limiting disease that does not need antibiotic therapy, however, patients with severe infection and immunocompromised patients should be treated with a combination of an aminoglycoside and doxycycline [24].


Campylobacter spp. including campylobacter jejuni and campylobacter coli are gram-negative bacteria that usually result in campylobacter enteritis. This organism normally lives in the gastrointestinal tract of many animals. Direct contact with infected animals or their products is a leading cause of campylobacter transmission. Dogs and puppies are the major reservoirs for campylobacter. For example, in a study it was demonstrated that about 47% of the fecal specimens of dogs’ campylobacter was isolated [25,26]. The incubation period in campylobacter enteritis varies from one to seven days. Most of the patients present fever, vomiting, diarrhea, and abdominal pain. Also, bloody diarrhea may be present in more than 50 percent of the infected patients. Convulsion and seizure may be observed in some patients [27]. This infection is usually self-limited and does not need antimicrobial therapy. Focus on correction of electrolyte imbalance and hydration should be considered. Antibiotic therapy with fluoroquinolones, macrolides, or aminoglycosides is indicated in patients with severe disease [28].


Capnocytophaga canimorsus is a gram-negative bacterium, which is found in the normal flora of the oropharyngeal tract of dogs and cats. The pathogen is mostly transmitted to human by dogs bite and causes an overwhelming sepsis, particularly in elderly, immunocompromised or asplenic patients [25]. The pathogen can also lead to other fatal infections including meningitis, osteomyelitis, arthritis, lung abscess or empyema and endocarditis. In addition, thrombotic thrombocytopenic purpura and hemolytic uremic syndrome can be associated with capnocytophaga septicemia especially in immunocompromised patients [25,29]. The literature data have demonstrated that the mortality rate due to capnocytophaga septicemia is estimated to be of one third of the infected patients. Accordingly, early empirical therapy with third generation cephalosporins in patients who received a dog bite should be considered [30].

Bordetella bronchiseptica

Bordetella bronchiseptica is a gram-negative rod bacterium belonging to the genus Bordetella. The pathogen normally lives in the upper respiratory tract of the mammals such as dogs and cats and is transmitted to humans by aerosol. B. bronchiseptica can lead to acute tracheobronchitis in dogs, which presents with harsh and kennel cough [31,32]. Human infection with B. bronchiseptica is very rare however, the pathogen can also cause pneumonia and upper respiratory tract infection in dog owners [33]. Evidences demonstrated that this organism is resistant to macrolides and cephalosporins however, in several studies, the organism was sensitive to fluoroquinolones and Trimethoprim/ sulfamethoxazole [34].

Coxiella burnetii

C. burnetii is an obligate intracellular gram-negative bacterium that causes Q fever in humans. The pathogen normally infects individuals via aerosol and direct contact with the body fluids of the infected animals. Although dogs are not the main reservoirs for C. burnetii, however, in a study it was demonstrated that C. burnetii was isolated from approximately 10 percent of farm dogs [35]. In addition, in another study by Buhariwalla and colleagues, it was reported that C. burnetii could be transmitted to human from an infected parturient dog. In addition, the patients developed the symptoms of Q fever including fever, chills, nausea, vomiting and productive cough. Opacity is a common finding in chest radiography, and, in physical examination, crackles may be heard during auscultation. The incubation period in this study was estimated to be between 8 and 12 days after the exposure to the infected animal. The patients with C. burnetii can be treated with fluoroquinolones or doxycycline successfully [36].

L. interrogans is an aerobic spirochete, which is the major cause of Leptospirosis in human. Leptospirosis is worldwide zoonoses that are mostly transmitted to human by environmental sources including contaminated soil, water, urine, or tissue of the infected animals. Rodents are the major reservoirs for Leptospirosis however, domestic animals including dogs can play an important role in leptospirosis transmission in endemic regions [37]. Mucosal surfaces of the human body including eye, vagina, nose, mouth, or erosive lesions, which have a direct contact with the contaminated urine, are the main ways of Leptospirosis transmission. The incubation period for this infection is averagely of about 10 days (ranging from 2 to 26 days) [38,39]. Leptospirosis may present with a variety of symptoms from no symptom to fever, nonproductive cough, headache, musculoskeletal pain, diarrhea, nausea, vomiting, alveolar hemorrhage, and even meningitis [39]. Several antibiotics such as doxycycline, ceftriaxone, cefotaxime, penicillin, amoxicillin, and ampicilin have been successfully employed for the treatment of Leptospirosis [40].

Staphylococcus intermedius

S. intermedius is a gram-positive bacterium with a coagulase activity that normally lives in the anterior part of the nasal cavity of several animals such as dogs, pigeons, and horses. Some evidences demonstrated that this pathogen could also be isolated from the gingival of healthy dogs [41]. S. intermedius is not a common zoonotic pathogen in humans however, several studies demonstrated that this bacterium is a potential pathogen associated with dog bite wounds and cellulitis can develop in inflicted humans [42,43]. This pathogen should be discriminated from staphylococcus aureus. Penicillin and amoxicillin-clavulanate are effective in the treatment of this infection [44].

Methicillin resistance staphylococcus aureus

Methicillin resistance staphylococcus aureus (MRSA) is a major cause of fatal infection in humans. Several investigations have reported that this pathogen has been isolated from some animals such as pigs, horses, cattle, cats and dogs. Of them, some believed that companion animals were the main reservoirs for the transmission of MRSA, being able to transmit the bacterium by direct contact with their owners. However, it seems that animal to human infection of MRSA is more seen in immunocompromised patients. Nevertheless, some evidences showed that this bacterium could be transmitted to healthy humans who own an infected animal [45,46]. Traditional anti staphylococcal antibiotics are not more effective in the treatment of infections caused by MRSA. Accordingly, newer drugs including vancomycin, linezolid and daptomycin are widely used in the treatment of MRSA infections [47].

Human Papillomaviruses Infection and Clinical Manifestations of Disease

Mucosal human papillomaviruses infections

Box 1

  • Condyloma acuminatum is one of the most common manifestations of HPV in the genital area 43 . They present as papules, nodules or soft, filiform, pinkish, sessile or pedunculated growths. In men, genital condylomas more commonly involve the coronal sulcus, the glands penis, and the penile shaft. In women, lesions commonly affect the external genitalia and the cervix 44 . The disease is usually sexually transmitted and is most frequently caused by low-risk HPVs, such as HPV 6 and 11, although many other genotypes can also be found, including HPV 2, 16, 18, 30–33, 35, 39, 41–45, 51–56, and 59 45-47 . As described in the text, the HPV types that cause benign genital warts can also cause problematic papillomas at oral sites, which can be difficult to treat because of their location.
  • Focal epithelial hyperplasia is a rare HPV-related disease of the oral mucosa that is more common in children and women. Lesions are mainly located in the lower lip, but less frequently may affect the upper lip, tongue, oral mucosa, oropharynx, palate, and floor of mouth. HPV 13 and 32 are the most common cause 48 .
  • Cervical neoplasia and cervical cancer. Precancerous cervical lesions are classified as c ervical CIN of different grades (1, 2, or 3). CIN1 pathology is broadly equivalent to the LSIL designation used in the Bethesda classification system, with CIN2 and 3 being equivalent to high-grade squamous intraepithelial lesion. The severity of neoplasia reflects the extent to which basal-like cells (i.e. poorly differentiated cells with a high nuclear/cytoplasmic ratio) extend toward the epithelial surface and the extent of suprabasal cell division. Low-grade lesions typically show evidence of productive viral infection with the presence of koilocytes in the suprabasal cell layers being regarded as a key manifestation of CIN1/LSIL. HPV is detectable in 90–100% of cervical abnormalities, ranging from incipient cytological abnormalities and dysplasia 49 to cervical cancer 50-52 .
  • Other anogenital cancers including those of the vulva, vagina, penis, and anus. Most vulvar cancers (92%) are solitary, keratinizing SCC. HPV prevalence is 90% in vulvar intraepithelial neoplasia and basaloid or warty cancers, but is found in only 6% of keratinizing SCC 53, 54 . HPV 16 is the most prominent type in vulvar cancer, with HPV 18, 21, 31, 33, and 34 detected at lower frequencies. In addition, HPV is responsible for 85% of vaginal cancer, with HPV 16 being detected in 60% of invasive tumors. HPV is also detected in basaloid and warty cancers of the penis, but only rarely in keratinizing SCC and verrucous cancers of the penis. In invasive penile cancer, HPV 16 is the most prevalent type (40–70%), followed by HPV 6 (22%), 52 (15%), and 11 (4%) 55 . HPV is present in 80–96% of anal cancer with HPV 16 being the most prevalent type 56 . Anal cancer is more common in men who have sex with men, individuals with a history of anal warts, and in immunosuppressed populations.
  • Head and neck cancer HPV is recognized as a major risk factor for the development of HNSCC. A recent meta-analysis showed that HPV prevalence in HNSCC increased significantly from 41% in 2000 to 72% in 2004 57 . HPV prevalence is significantly higher in oropharynx SCC than in the oral cavity with the tonsil having higher prevalence than other anatomic sites 58 . These HPV-associated cancers display clinical and molecular features distinct from other HNSCCs. The patients with HPV-positive cancer have at least a 50% improvement in overall survival at 5 years, which is equivalent to an approximate 30% difference in absolute survival. HPV association is now part of routine diagnostic procedure when assessing the prognosis of HNSCC. HPV 16 is the most common type found in HNSCC, but other HPV types such as 18, 31, 33, and 35 can also be detected 57 .

Cutaneous human papillomaviruses infections

Box 2

  • Common warts can be single or multiple and of varying sizes. They occur at many sites, but often on the back of hands 64 , with the knee also being a common site of infection in children. A prevalence of 3.5% 65 in adults to over 30% in schoolchildren has been reported 66 . Incidence increases in immunosuppressed patients, with lesions being more numerous and more recalcitrant. HPV 1, 2, 4, 27, and 57 are most prevalent types 67-69 ]. HPV 7 is found in the common warts of individuals whose hands are chronically exposed to moisture and cold because of their occupation 70 .
  • Plantar warts occur on the soles of the feet, particularly in children. HPV 1 and 4 are frequently the cause, although HPV 57, 60, 63, 65, and 66 can also be involved 68 . HPV 1 commonly induces lesions that manifest as a keratotic plug surrounded by a hyperkeratotic rim that are often painful. HPV 4 can be the cause of mosaic warts, which are more superficial lesions that occur in a confluent cobblestone pattern and are usually painless. Persistent plantar lesions can be very rarely associated with the development of verrucous carcinoma 72 .
  • Flat warts are slightly raised lesions of skin color or pigmented, with flat, smooth or, slightly rough surface. The face and back of hands are the most common sites of disease with HPV 3 and 10 most commonly detected in such lesions 64, 73 .
  • Filiform warts are pedunculated lesions growing in a perpendicular or oblique way in relation to the skin surface. The face and neck are the most frequent sites of disease. The detected HPV types are the same as common warts, especially HPV 2 73 .
  • Pigmented warts range from gray to blackish brown and are located on the palmoplantar or lateral surfaces of the hands, feet, fingers, and toes. HPV 4, 60, and 65 are most prevalent in such lesions 74 .
  • Epidermoid cysts can be caused by HPV types 57 and 60, with these types being detected in plantar epidermoid cysts 75, 76 . An unknown HPV type was reported in epidermoid cysts of the trunk and scalp 77, 78 . Immunostaining suggests that such lesions are distinct from the associated dermal eccrine duct, but have similarities with the suprabasal cells of the epidermis. It has been suggested that palmoplantar epidermoid cysts may in some instances arise as a result of epidermoid metaplasia of eccrine ducts following HPV infection 79 .
  • Skin cancer. Bowen's disease (BD) is a SCC in situ of the skin. In 3–5% of cases, it progresses to invasive carcinoma with the capability to develop metastasis. The mucosal HPV types are commonly detected in lesions of extra-genital BD, especially in the periungual region. Other HPV types have occasionally been detected in BD, including HPV 2, 6, 11, 54, 58, 61, 62, and 73 80 . The link between HPV and non-melanoma skin cancer, SCC and BCC, is not clear except in immunosuppressed individuals and in certain genetic backgrounds. Mucosal HPV types, especially HPV 16 can sometimes be detected in the SCC and BCC of the skin, but also more rarely HPV 2, 31, 34, 35, 58, 61, and 73 81, 82 . Molecular analysis of Beta HPV protein function and serology suggests a role of certain Beta HPV types (e.g. HPV 8, 20, 38) in the development of SCC in immunosuppressed individuals. A role in the early stages of cancer development is suspected (but not conclusively proven) in a fraction of keratinocyte cancers in the general population, with Beta HPV genomes from the cell being lost from the cell as the disease severity increases 83 .

Why fathers don't pass on mitochondria to offspring

Offering insights into a long-standing and mysterious bias in biology, a new study reveals how and why mitochondria are only passed on through a mother's egg -- and not the father's sperm. What's more, experiments from the study show that when paternal mitochondria persist for longer than they should during development, the embryo is at greater risk of lethality.

Harbored inside the cells of nearly all multicellular animals, plants and fungi are mitochondria, organelles that play an important role in generating the energy that cells need to survive. Shortly after a sperm penetrates an egg during fertilization, the sperm's mitochondria are degraded while the egg's mitochondria persist. To gain more insights into this highly specific degradation pattern, Qinghua Zhou et al. used electron microscopy and tomography to study sperm mitochondria (or paternal mitochondria) in Caenorhabditis elegans, a type of roundworm, during early stages of development.

Intriguingly, the paternal mitochondria were found to partially self-destruct before the mitochondria were surrounded by autophagosomes, which target components within a cell and facilitate their degradation. This suggests that another mechanism, something within the paternal mitochondrion itself, initiates the degradation process. RNA analysis of paternal mitochondria during early stages of embryonic development hinted that it is the cps-6 gene that facilitates this process, which the team confirmed by studying sperm lacking cps-6 without it, paternal mitochondria remained significantly later into the development stage.

Further investigation suggests that the enzyme that cps-6 encodes first breaks down the interior membrane of the paternal mitochondria before moving to the space within the inner membrane to breakdown mitochondrial DNA. When the researchers engineered paternal mitochondria to breakdown during later stages of development, this increased the chances that the embryo would not survive, suggesting that the transmission of paternal mitochondria is an evolutionary disadvantage.

Collectively, results from this study suggest that cps-6 plays a key role in initiating the self-destruction of paternal sperm, which likely benefits the embryo.

Can Pets Contract Coronavirus from Humans or Vice Versa?

Dr. Niels Pedersen, a distinguished emeritus professor at the UC Davis School of Veterinary Medicine and a renowned expert on infectious and immunologic diseases in dogs and cats, addresses the question, "Can pets contract coronavirus from humans or vice versa?"

The simple answer is as follows: No, you won’t get or give the coronavirus to your family pet. Coronaviruses occur in virtually every species of animal, including humans, and are commonly associated with unapparent or transient intestinal and respiratory infections. They tend to be very species specific and cross-species transmission is uncommon.

The more complex answer goes like this: Coronaviruses have adapted themselves by mutation over a period of 50,000 years or more to virtually every species of animal, including humans. They only cause disease in their new species and tend to remain in that species in whatever genetic form that allows adaptation to their new hosts.

The various coronaviruses have been sequenced and their relationship to each other determined. The common cold-causing coronaviruses of humans (OC43, 229E and NL63) are in the alphacoronavirus group, along with the intestinal coronavirus of our pet cats and dogs. The more recently humanized strains of coronavirus, MERS, SARS and COVID-19 have jumped over from the betacoronaviruses of bats, possibly by intermediate infection of other animals such as camels and civet cats. Interestingly, MERS and SARS coronaviruses did not quite make the jump from bats to humans, and died out.

However, the new coronavirus appears to have successfully adapted to humans (i.e., it has become humanized) and is therefore looming as an even more severe disease problem than MERS and SARS. Viruses that have either not fully humanized, or have only recently adapted to humans, tend to cause much more severe disease, as is the case with the MERS-, SARS- and COVID-19.

Although coronaviruses can jump from one host to another, this is a slow process and requires significant genetic change. There is no evidence that coronaviruses of our common veterinary species have entered humans in the recent past or vice versa. However, the tendency for coronaviruses to jump species is an ongoing occurrence and it is possible that a coronavirus from a common pet species such as a cat or dog may enter humans and cause disease sometime in the future. However, if it should ever humanize, it will no longer be a cat or dog virus, but rather a new human virus. The same is true for a coronavirus of humans that decides to change their host species.

Nonrespiratory Bacterial Diseases

Fowl Cholera

Synonyms: avian pasteurellosis, cholera, avian hemorrhagic septicemia

Species affected: Domestic fowl of all species (primarily turkeys and chickens), game birds (especially pheasants and ducks), cage birds, wild birds, and birds in zoological collections and aviaries are susceptible.

Clinical signs: Fowl cholera usually strikes birds older than 6 weeks of age. In acute outbreaks, dead birds may be the first sign. Fever, reduced feed consumption, mucoid discharge from the mouth, ruffled feathers, diarrhea, and labored breathing may be seen. As the disease progresses birds lose weight, become lame from joint infections, and develop rattling noises from exudate in air passages. As fowl cholera becomes chronic, chickens develop abscessed wattles and swollen joints and foot pads. Caseous exudate may form in the sinuses around the eyes. Turkeys may have twisted necks (see Table 3).

Transmission: Multiple means of transmission have been demonstrated. Flock additions, free-flying birds, infected premises, predators, and rodents are all possibilities.

Treatment: A flock can be medicated with a sulfa drug (sulfonamides, especially sulfadimethoxine, sulfaquinonxalene, sulfamethazine, and sulfaquinoxalene) or vaccinated, or both, to stop mortality associated with an outbreak. It must be noted, however, that sulfa drugs are not FDA approved for use in pullets older than 14 weeks or for commercial laying hens. Sulfa drugs leave residues in meat and eggs. Antibiotics can be used, but require higher levels and long term medication to stop the outbreak.

Prevention: On fowl cholera endemic farms, vaccination is advisable. Do not vaccinate for fowl cholera unless you have a problem on the farm. Rodent control is essential to prevent future outbreaks.


Synonyms: navel ill, mushy chick disease

Species affected: chickens

Clinical signs: Affected chicks may have external navel infection, large unabsorbed yolk sacs, peritonitis with fetid odor, exudates adhering to the navel, edema of the skin of ventral body area, septicemia and dehydration (see Table 3).

Transmission: Infection occurs at the time of hatching or shortly thereafter, before navels are healed. Chicks from dirty hatching eggs or eggs with poor quality shells, or newly hatched chicks placed in dirty holding boxes, are most susceptible. Chicks removed prior to complete healing of the navel due to improper temperature and/or humidity are also more susceptible. Eggs that explode in the hatching tray contaminate other eggs in the tray and increase the incidence.

Treatment: There is no specific treatment for omphalitis. Most affected birds die in the first few days of life. Unaffected birds need no medication.

Prevention: Control is by prevention through effective hatchery sanitation, hatchery procedures, breeder flock surveillance, and proper preincubation handling of eggs. Mushy chicks should be culled from the hatch and destroyed. If chick mortality exceeds 3 percent, the breeder flocks and egg handling and hatching procedures should be reviewed.


Synonyms: bacillary white diarrhea, BWD

Species affected: Chickens and turkeys are most susceptible, although other species of birds can become infected. Pullorum has never been a problem in commercially grown game birds such as pheasant, chukar partridge, and quail. Infection in mammals is rare.

Clinical signs: Death of infected chicks or poults begins at 5&ndash7 days of age and peaks in another 4&ndash5 days. Clinical signs including huddling, droopiness, diarrhea, weakness, pasted vent, gasping, and chalk-white feces, sometimes stained with green bile. Affected birds are unthrifty and stunted because they do not eat (see Table 3). Survivors become asymptomatic carriers with localized infection in the ovary.

Transmission: Pullorum is spread primarily through the egg, from hen to chick. It can spread further by contaminated incubators, hatchers, chick boxes, houses, equipment, poultry by-product feedstuffs, and carrier birds.

Treatment: Treatment is for flock salvage only. Several sulfonamides, antibiotics, and antibacterials are effective in reducing mortality, but none eradicates the disease from the flock. Pullorum eradication is required by law. Eradication requires destroying the entire flock.

Prevention: Pullorum outbreaks are handled, on an eradication basis, by state/federal regulatory agencies. As part of the National Poultry Improvement Program, breeder replacement flocks are tested before onset of production to assure pullorum-free status. This mandatory law includes chickens, turkeys, show birds, waterfowl, game birds, and guinea fowl. In Florida, a negative pullorum test or certification that the bird originated from a pullorum-free flock is required for admission for exhibit at shows and fairs. Such requirements have been beneficial in locating pullorum-infected flocks of hobby chickens.

Necrotic Enteritis

Synonyms: enterotoxemia, rot gut

Species affected: Rapidly growing young birds, especially chickens and turkeys 2-12 weeks of age, are most susceptible. Necrotic enteritis is a disease associated with domestication and is unlikely to threaten wild bird populations. Necrotic enteritis is primarily a disease of broilers, roasters and turkeys. Ulcerative enteritis, on the other hand, commonly affects pullets and quail.

Clinical signs: Initially there is a reduction in feed consumption as well as dark, often blood-stained, feces. Infected chickens will have diarrhea. Chronically affected birds become emaciated. The bird, intestines, and feces emit a fetid odor (see Table 3).

Transmission: Necrotic enteritis does not spread directly from bird to bird. Bacteria are ingested along with infected soil, feces, or other infected materials. The bacteria then grow in the intestinal tract. Infection commonly occurs in crowded flocks, immuno-suppressed flocks, and flocks maintained in poor sanitary conditions.

Treatment: The clostridia bacteria involved in necrotic enteritis is sensitive to the antibiotics bacitracin, neomycin, and tetracycline. However, antibiotics such as penicillin, streptomycin, and novobiocin are also effective. Bacitracin is the most commonly used drug for control of necrotic enteritis. As with all drugs, legality and withdrawal time requirements must be observed.

Prevention: Prevention should be directed toward sanitation, husbandry, and management.

Ulcerative Enteritis

Synonyms: quail disease

Species affected: Captive quail are extremely susceptible and must be maintained on wire-bottom pens or on preventive medications. Chickens, turkeys, partridges, grouse, and other species are occasionally clinically affected.

Clinical signs: In quail, the disease is acute with high mortality. In chickens, signs are less dramatic. Acute signs are extreme depression and reduction in feed consumption. Affected birds sit humped with eyes closed. Other signs included emaciation, watery droppings streaked with urates, and dull ruffled feathers (see Table 3). Accumulated mortality will reach 50 percent if the flock is not treated.

Transmission: Birds become infected by direct contact with carrier birds, infected droppings or contaminated pens, feed and water. Bacteria are passed in the droppings of sick and carrier birds. Infection can be spread mechanically on shoes, feed bags, equipment, and from contamination by rodents and pets.

Treatment: Bacitracin and neomycin can be used singly or in combination. Other antibiotics and drugs such as tetracyclines, penicillin, Lincomycin, and Virginomycin are also effective. Consult a veterinarian for dose, route, and duration of treatment.

Prevention: Ulcerative enteritis is difficult to prevent in quail. When quail have access to their own droppings, this disease commonly occurs. To eradicate, depopulate stock, thoroughly clean and disinfect, and start over with young, clean stock.


Synonyms: limberneck, bulbar paralysis, western duck sickness, alkali disease

Species affected: All fowl of any age, humans, and other animals are highly susceptible. The turkey vulture is the only animal host known to be resistant to the disease.

Clinical signs: Botulism is a poisoning causing by eating spoiled food containing a neurotoxin produced by the bacterium Clostridium botulinum. Paralysis, the most common clinical sign, occurs within a few hours after poisoned food is eaten. Pheasants with botulism remain alert, but paralyzed. Legs and wings become paralyzed, then the neck becomes limp. Neck feathers become loose in the follicle and can be pulled easily (see Table 3).

If the amount eaten is lethal, prostration and death follow in 12 to 24 hours. Death is a result of paralysis of respiratory muscles. Fowl affected by sublethal doses become dull and sleepy.

Transmission: Botulism is common in wild ducks and is a frequent killer of waterfowl because the organisms multiply in dead fish and decaying vegetation along shorelines.

Decaying bird carcasses on poultry ranges, wet litter or other organic matter, and fly maggots from decaying substances may harbor botulism. There is no spread from bird to bird.

Treatment: Remove spoiled feed or decaying matter. Flush the flock with Epsom salts (1 lb/1000 hens) in water or in wet mash. It has been reported that potassium permanganate (1:3000) in the drinking water is helpful. Affected birds can be treated with botulism antitoxin injections.

Prevention: Incinerate or bury dead birds promptly. Do not feed spoiled canned vegetables. Control flies. Replace suspected feed.


Synonyms: staph infection, staph septicemia, staph arthritis, bumblefoot

Species affected: All fowl, especially turkeys, chickens, game birds, and waterfowl, are susceptible.

Clinical signs: Staphylococcal infections appear in three forms—septicemia (acute), arthritic (chronic), and bumblefoot. The septicemia form appears similar to fowl cholera in that the birds are listless, without appetite, feverish, and show pain during movement. Black rot may show up in eggs (the organism is passed in the egg). Infected birds pass fetid watery diarrhea. Many will have swollen joints (arthritis) and production drops (see Table 3).

The arthritic form follows the acute form. Birds show symptoms of lameness and breast blisters, as well as painful movement (see Table 3). Birds are reluctant to walk, preferring to sit rather than stand.

Bumblefoot is a localized chronic staph infection of the foot, thought to be caused by puncture injuries. The bird becomes lame from swollen foot pads (see Table 3).

Transmission: Staphylococcus aureus is soil-borne and outbreaks in flocks often occur after storms when birds on range drink from stagnant rain pools.

Treatment: Novobiocin (350 g/ton) can be given in the feed for 5&ndash7 days. Erythromycin and penicillin can be administered in the water for 3-5 days or in the feed (200 g/ton) for 5 days. Other antibiotics and drugs are only occasionally effective.

Prevention: Remove objects that cause injury. Isolate chronically affected birds. Provide nutritionally balanced feed.

Watch the video: Κορωνοϊός Tι πρέπει να γνωρίζετε (November 2022).