Can viruses pass through sweat pores?

Can viruses pass through sweat pores?

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I have read somewhere that viruses and other microbes can not penetrate skin but what about sweat pores? Can viruses pass through these pores?

'Pore' is a confusing term. Sweat is produced in sweat glands, and subsequently excreted through a duct, as indicated in the image below (sudoriferous ~).

In short, viruses cannot enter the body through these glands because the glands don't really open up into the body, but instead the inside of the sweat gland is lined with sweat-producing cells (fig 2 and 3).

A passive protection mechanism preventing infection is similar to the mechanism by which the bladder is guarded from infection through the urethra: even if some malignant agent were to enter the sweat duct, it is simply pushed out by the excreted sweat.

Figure one: Sweat glands in skin. Source: wikimedia commons.


Figure two: Slide of sweat gland. Tightly packed secretory cells dump sweat into the lumen through exocytosis (see fig 3). Source: University of Western Australia.

Figure three: Exocytosis. The lining of the sweat gland contains cells producing sweat through exocytosis. Viruses and other pathogens cannot simply enter these cells, and also cannot 'slip in between' the cells. Source: wikimedia commons.

13.74: Skin

  • Contributed by CK-12: Biology Concepts
  • Sourced from CK-12 Foundation

What is integumentary?

Because the organs of the integumentary system are external to the body, you may think of them as little more than &ldquoaccessories,&rdquo like clothing or jewelry. But the organs of the integumentary system serve important biological functions. They provide a protective covering for the body and help the body maintain homeostasis.


Not all STIs are symptomatic, and symptoms may not appear immediately after infection. In some instances a disease can be carried with no symptoms, which leaves a greater risk of passing the disease on to others. Depending on the disease, some untreated STIs can lead to infertility, chronic pain or death. [14]

The presence of an STI in prepubescent children may indicate sexual abuse. [15]


A sexually transmitted infection present in a pregnant woman may be passed on to the infant before or after birth. [16]

    [17][17] (25–30%) (rare) [18][17] (1%) [19]
    (low risk) [20] (0.01%) [21] (unknown)
    (30–50%) [20] (22%) [22] (0.07% for HSV-2) [23] (0.05%) [21][23] (high: around 40–50%) [24][30][31][32][33][34]
  • Mycoplasma genitalium[35][36][37]
  • Ureaplasma infection[38][39][34]
    (30–50%) [20] (47%) [25] (50–70%) (0.1%) [21] (high [20] around 40–50%) [24][30][31][34][38][39][34]


    (Haemophilus ducreyi) (Chlamydia trachomatis) (Neisseria gonorrhoeae), colloquially known as "the clap" or (Klebsiella granulomatis)
  • Mycoplasma genitalium[31][43][44][45]
  • Mycoplasma hominis[30][31][32][33][46] (Treponema pallidum) [38][39]



    (hepatitis B virus)—saliva, venereal fluids.
    (Note: hepatitis A and hepatitis E are transmitted via the fecal-oral route hepatitis C is rarely sexually transmittable, [47] and the route of transmission of hepatitis D (only if infected with B) is uncertain, but may include sexual transmission. [48][49][50] ) (Herpes simplex virus 1, 2) skin and mucosal, transmissible with or without visible blisters (Human Immunodeficiency Virus)—venereal fluids, semen, breast milk, blood (Human Papillomavirus)—skin and mucosal contact. 'High risk' types of HPV cause almost all cervical cancers, as well as some anal, penile, and vulvar cancer. [51] Some other types of HPV cause genital warts. (molluscum contagiosum virus MCV)—close contact [52]


    , colloquially known as "crabs" or "pubic lice" (Pthirus pubis) [53][54][55] The infestation and accompanying inflammation is Pediculosis pubis (Sarcoptes scabiei) (Trichomonas vaginalis), colloquially known as "trich"

Main types

Sexually transmitted infections include:

    is a sexually transmitted infection caused by the bacterium Chlamydia trachomatis. In women, symptoms may include abnormal vaginal discharge, burning during urination, and bleeding in between periods, although most women do not experience any symptoms. [56] Symptoms in men include pain when urinating, and abnormal discharge from their penis. [57] If left untreated in both men and women, Chlamydia can infect the urinary tract and potentially lead to pelvic inflammatory disease (PID). PID can cause serious problems during pregnancy and even has the potential to cause infertility. It can cause a woman to have a potentially deadly ectopic pregnancy, in which the egg implants outside of the uterus. However, Chlamydia can be cured with antibiotics.
  • The two most common forms of herpes are caused by infection with herpes simplex virus (HSV). HSV-1 is typically acquired orally and causes cold sores, HSV-2 is usually acquired during sexual contact and affects the genitals, however either strain may affect either site. [58] Some people are asymptomatic or have very mild symptoms. Those that do experience symptoms usually notice them 2 to 20 days after exposure which last 2 to 4 weeks. Symptoms can include small fluid-filled blisters, headaches, backaches, itching or tingling sensations in the genital or anal area, pain during urination, Flu like symptoms, swollen glands, or fever. Herpes is spread through skin contact with a person infected with the virus. The virus affects the areas where it entered the body. This can occur through kissing, vaginal intercourse, oral sex or anal sex. The virus is most infectious during times when there are visible symptoms, however those who are asymptomatic can still spread the virus through skin contact. [59] The initial infection and symptoms are usually the most severe because the body does not have any antibodies built up. After the primary attack, one might have recurring attacks that are milder or might not even have future attacks. There is no cure for the disease but there are antiviral medications that treat its symptoms and lower the risk of transmission (Valtrex). Although HSV-1 is typically the "oral" version of the virus, and HSV-2 is typically the "genital" version of the virus, a person with HSV-1 orally CAN transmit that virus to their partner genitally. The virus, either type, will settle into a nerve bundle either at the top of the spine, producing the "oral" outbreak, or a second nerve bundle at the base of the spine, producing the genital outbreak.
  • The human papillomavirus (HPV) is the most common STI in the United States. [60] There are more than 40 different strands of HPV and many do not cause any health problems. In 90% of cases the body's immune system clears the infection naturally within 2 years. [61] Some cases may not be cleared and can lead to genital warts (bumps around the genitals that can be small or large, raised or flat, or shaped like cauliflower) or cervical cancer and other HPV related cancers. Symptoms might not show up until advanced stages. It is important for women to get pap smears in order to check for and treat cancers. There are also two vaccines available for women (Cervarix and Gardasil) that protect against the types of HPV that cause cervical cancer. HPV can be passed through genital-to-genital contact as well as during oral sex. It is important to remember that the infected partner might not have any symptoms. is caused by bacterium that lives on moist mucous membranes in the urethra, vagina, rectum, mouth, throat, and eyes. The infection can spread through contact with the penis, vagina, mouth or anus. Symptoms of gonorrhea usually appear 2 to 5 days after contact with an infected partner however, some men might not notice symptoms for up to a month. Symptoms in men include burning and pain while urinating, increased urinary frequency, discharge from the penis (white, green, or yellow in color), red or swollen urethra, swollen or tender testicles, or sore throat. Symptoms in women may include vaginal discharge, burning or itching while urinating, painful sexual intercourse, severe pain in lower abdomen (if infection spreads to fallopian tubes), or fever (if infection spreads to fallopian tubes) however, many women do not show any symptoms. [62] There are some antibiotic resistant strains for Gonorrhea but most cases can be cured with antibiotics.
    is an STI caused by a bacterium. Untreated, it can lead to complications and death. [63] Clinical manifestations of syphilis include the ulceration of the uro-genital tract, mouth or rectum if left untreated the symptoms worsen. In recent years, the prevalence of syphilis has declined in Western Europe, but it has increased in Eastern Europe (former Soviet states). A high incidence of syphilis can be found in places such as Cameroon, Cambodia, Papua New Guinea. [64] Syphilis infections are increasing in the United States. [65] is a common STI that is caused by infection with a protozoan parasite called Trichomonas vaginalis. [66] Trichomoniasis affects both women and men, but symptoms are more common in women. [67] Most patients are treated with an antibiotic called metronidazole, which is very effective. [68] (human immunodeficiency virus) damages the body's immune system, which interferes with its ability to fight off disease-causing agents. The virus kills CD4 cells, which are white blood cells that help fight off various infections. HIV is carried in body fluids, and is spread by sexual activity. It can also be spread by contact with infected blood, breast feeding, childbirth, and from mother to child during pregnancy. [69] When HIV is at its most advanced stage, an individual is said to have AIDS (acquired immunodeficiency syndrome). [70] There are different stages of the progression of and HIV infection. The stages include primary infection, asymptomatic infection, symptomatic infection, and AIDS. In the primary infection stage, an individual will have flu like symptoms (headache, fatigue, fever, muscle aches) for about 2 weeks. In the asymptomatic stage, symptoms usually disappear, and the patient can remain asymptomatic for years. When HIV progresses to the symptomatic stage, the immune system is weakened, and has a low cell count of CD4+ T Cells. When the HIV infection becomes life-threatening, it is called AIDS. People with AIDS fall prey to opportunistic infections and die as a result. [56] When the disease was first discovered in the 1980s, those who had AIDS were not likely to live longer than a few years. There are now antiretroviral drugs (ARVs) available to treat HIV infections. There is no known cure for HIV or AIDS but the drugs help suppress the virus. By suppressing the amount of virus in the body, people can lead longer and healthier lives. Even though their virus levels may be low they can still spread the virus to others. [71]

Viruses in semen

Twenty-seven different viruses have been identified in semen. Information on whether or not transmission occurs or whether the viruses cause disease is uncertain. Some of these microbes are known to be sexually transmitted. [72] Those found in semen are listed by the CDC. [72]

Microbes known to be sexually transmissible (but not generally considered STIs) include:

    – Virus in semen for seven weeks after clinical recovery. [73] (both types 1 and 2) – Sexually transmissible, consumption of breast milk breastfeeding, and once mistaken as a HIV, risk of leukemia. [74]

Many STIs are (more easily) transmitted through the mucous membranes of the penis, vulva, rectum, urinary tract and (less often—depending on type of infection) the mouth, throat, respiratory tract and eyes. [75] The visible membrane covering the head of the penis is a mucous membrane, though it produces no mucus (similar to the lips of the mouth). Mucous membranes differ from skin in that they allow certain pathogens into the body. The amount of contact with infective sources which causes infection varies with each pathogen but in all cases, a disease may result from even light contact from fluid carriers like venereal fluids onto a mucous membrane. [ citation needed ]

Some STIs such as HIV can be transmitted from mother to child either during pregnancy or breastfeeding. [76] [ citation needed ]

Healthcare professionals suggest safer sex, such as the use of condoms, as a reliable way of decreasing the risk of contracting sexually transmitted diseases during sexual activity, but safer sex cannot be considered to provide complete protection from an STI. The transfer of and exposure to bodily fluids, such as blood transfusions and other blood products, sharing injection needles, needle-stick injuries (when medical staff are inadvertently jabbed or pricked with needles during medical procedures), sharing tattoo needles, and childbirth are other avenues of transmission. These different means put certain groups, such as medical workers, and haemophiliacs and drug users, particularly at risk. [ citation needed ]

It is possible to be an asymptomatic carrier of sexually transmitted diseases. In particular, sexually transmitted diseases in women often cause the serious condition of pelvic inflammatory disease. [ citation needed ]

Testing may be for a single infection, or consist of a number of tests for a range of STIs, including tests for syphilis, trichomonas, gonorrhea, chlamydia, herpes, hepatitis and HIV. No procedure tests for all infectious agents. [ citation needed ]

STI tests may be used for a number of reasons: [ citation needed ]

  • as a diagnostic test to determine the cause of symptoms or illness
  • as a screening test to detect asymptomatic or presymptomatic infections
  • as a check that prospective sexual partners are free of disease before they engage in sex without safer sex precautions (for example, when starting a long term mutually monogamous sexual relationship, in fluid bonding, or for procreation).
  • as a check prior to or during pregnancy, to prevent harm to the baby
  • as a check after birth, to check that the baby has not caught an STI from the mother
  • to prevent the use of infected donated blood or organs
  • as part of the process of contact tracing from a known infected individual
  • as part of mass epidemiological surveillance

Early identification and treatment results in less chance to spread disease, and for some conditions may improve the outcomes of treatment. There is often a window period after initial infection during which an STI test will be negative. During this period, the infection may be transmissible. The duration of this period varies depending on the infection and the test. Diagnosis may also be delayed by reluctance of the infected person to seek a medical professional. One report indicated that people turn to the Internet rather than to a medical professional for information on STIs to a higher degree than for other sexual problems. [77]


Until the 1990s, [ citation needed ] STIs were commonly known as venereal diseases, an antiquated euphemism derived from the Latin venereus, being the adjectival form of Venus, the Roman goddess of love. [78] However in the post-classical education era the euphemistic effect was entirely lost, and the common abbreviation "VD" held only negative connotations. Other former euphemisms for STIs include "blood diseases" and "social diseases". [79] The present euphemism is in the use of the initials "STI" rather than in the words they represent. The World Health Organization (WHO) has recommended the more inclusive term sexually transmitted infection since 1999. [13] Public health officials originally introduced the term sexually transmitted infection, which clinicians are increasingly using alongside the term sexually transmitted disease in order to distinguish it from the former. [ citation needed ]

Strategies for reducing STI risk include: vaccination, mutual monogamy, reducing the number of sexual partners, and abstinence. [80] Behavioral counseling for all sexually active adolescents and for adults who are at increased risk. [81] Such interactive counseling, which can be resource intensive, is directed at a person's risk, the situations in which risk occurs, and the use of personalized goal-setting strategies. [82]

The most effective way to prevent sexual transmission of STIs is to avoid contact of body parts or fluids which can lead to transfer with an infected partner. Not all sexual activities involve contact: cybersex, phonesex or masturbation from a distance are methods of avoiding contact. Proper use of condoms reduces contact and risk. Although a condom is effective in limiting exposure, some disease transmission may occur even with a condom. [83]

Both partners can get tested for STIs before initiating sexual contact, or before resuming contact if a partner engaged in contact with someone else. Many infections are not detectable immediately after exposure, so enough time must be allowed between possible exposures and testing for the tests to be accurate. Certain STIs, particularly certain persistent viruses like HPV, may be impossible to detect. [ medical citation needed ]

Some treatment facilities utilize in-home test kits and have the person return the test for follow-up. Other facilities strongly encourage that those previously infected return to ensure that the infection has been eliminated. Novel strategies to foster re-testing have been the use of text messaging and email as reminders. These types of reminders are now used in addition to phone calls and letters. [84] After obtaining a sexual history, a healthcare provider can encourage risk reduction by providing prevention counseling. Prevention counseling is most effective if provided in a nonjudgmental and empathetic manner appropriate to the person's culture, language, gender, sexual orientation, age, and developmental level. Prevention counseling for STIs is usually offered to all sexually active adolescents and to all adults who have received a diagnosis, have had an STI in the past year, or have multiple sex partners. [82]


Vaccines are available that protect against some viral STIs, such as Hepatitis A, Hepatitis B, and some types of HPV. [85] Vaccination before initiation of sexual contact is advised to assure maximal protection. The development of vaccines to protect against gonorrhea is ongoing. [86]


Condoms and female condoms only provide protection when used properly as a barrier, and only to and from the area that they cover. Uncovered areas are still susceptible to many STIs. [ citation needed ]

In the case of HIV, sexual transmission routes almost always involve the penis, as HIV cannot spread through unbroken skin therefore, properly shielding the penis with a properly worn condom from the vagina or anus effectively stops HIV transmission. An infected fluid to broken skin borne direct transmission of HIV would not be considered "sexually transmitted", but can still theoretically occur during sexual contact. This can be avoided simply by not engaging in sexual contact when presenting open, bleeding wounds. [ citation needed ]

Other STIs, even viral infections, can be prevented with the use of latex, polyurethane or polyisoprene condoms as a barrier. Some microorganisms and viruses are small enough to pass through the pores in natural skin condoms, but are still too large to pass through latex or synthetic condoms. [ citation needed ]

Proper male condom usage entails: [ citation needed ]

  • Not putting the condom on too tight at the tip by leaving 1.5 centimetres (0.6 in) room for ejaculation. Putting the condom on too tightly can and often does lead to failure.
  • Wearing a condom too loose can defeat the barrier
  • Avoiding inverting or spilling a condom once worn, whether it has ejaculate in it or not
  • If a user attempts to unroll the condom, but realizes they have it on the wrong side, then this condom may not be effective
  • Being careful with the condom if handling it with long nails
  • Avoiding the use of oil-based lubricants (or anything with oil in it) with latex condoms, as oil can eat holes into them
  • Using flavored condoms for oral sex only, as the sugar in the flavoring can lead to yeast infections if used to penetrate

In order to best protect oneself and the partner from STIs, the old condom and its contents are to be treated as infectious and properly disposed of. A new condom is used for each act of intercourse, as multiple usage increases the chance of breakage, defeating the effectiveness as a barrier. [ citation needed ]

In case of female condoms, the device consists of two rings, one in each terminal portion. The larger ring should fit snugly over the cervix and the smaller ring remains outside the vagina, covering the vulva. This system provides some protection of the external genitalia. [87]


The cap was developed after the cervical diaphragm. Both cover the cervix and the main difference between the diaphragm and the cap is that the latter must be used only once, using a new one in each sexual act. The diaphragm, however, can be used more than once. These two devices partially protect against STIs (they do not protect against HIV). [88]

Researchers had hoped that nonoxynol-9, a vaginal microbicide would help decrease STI risk. Trials, however, have found it ineffective [89] and it may put women at a higher risk of HIV infection. [90] There is evidence that vaginal dapivirine probably reduces HIV in women who have sex with men, other types of vaginal microbicides have not demonstrated effectiveness for HIV or STI's. [91]

There is little evidence that school-based interventions such as sexual and reproductive health education programmes on contraceptive choices and condoms are effective on improving the sexual and reproductive health of adolescents. Incentive-based programmes may reduce adolescent pregnancy but more data is needed to confirm this. [92]

Specific age groups, persons who participate in risky sexual behavior, or those have certain health conditions may require screening. The CDC recommends that sexually active women under the age of 25 and those over 25 at risk should be screened for chlamydia and gonorrhea yearly. Appropriate times for screening are during regular pelvic examinations and preconception evaluations. [93] Nucleic acid amplification tests are the recommended method of diagnosis for gonorrhea and chlamydia. [94] This can be done on either urine in both men and women, vaginal or cervical swabs in women, or urethral swabs in men. [94] Screening can be performed:

  • to assess the presence of infection and prevent tubal infertility in women
  • during the initial evaluation before infertility treatment
  • to identify HIV infection
  • for men who have sex with men
  • for those who may have been exposed to hepatitis C
  • for HCV [94]

In the case of rape, the person can be treated prophylacticly with antibiotics. [95]

An option for treating partners of patients (index cases) diagnosed with chlamydia or gonorrhea is patient-delivered partner therapy, which is the clinical practice of treating the sex partners of index cases by providing prescriptions or medications to the patient to take to his/her partner without the health care provider first examining the partner. [96] [ needs update ]

In 2008, it was estimated that 500 million people were infected with either syphilis, gonorrhea, chlamydia or trichomoniasis. [1] At least an additional 530 million people have genital herpes and 290 million women have human papillomavirus. [1] STIs other than HIV resulted in 142,000 deaths in 2013. [98] In the United States there were 19 million new cases of sexually transmitted infections in 2010. [11]

In 2010, 19 million new cases of sexually transmitted infections occurred in women in the United States. [5] A 2008 CDC study found that 25–40% of U.S. teenage girls has a sexually transmitted disease. [99] [100] Out of a population of almost 295,270,000 people [101] there were 110 million new and existing cases of eight sexually transmitted infections. [102]

Over 400,000 sexually transmitted infections were reported in England in 2017, about the same as in 2016, but there were more than 20% increases in confirmed cases of gonorrhoea and syphilis. Since 2008 syphilis cases have risen by 148%, from 2,874 to 7,137, mostly among men who have sex with men. The number of first cases of genital warts in 2017 among girls aged 15–17 years was just 441, 90% less than in 2009 – attributed to the national human papilloma virus immunisation programme. [103]

AIDS is among the leading causes of death in present-day Sub-Saharan Africa. [104] HIV/AIDS is transmitted primarily via unprotected sexual intercourse. More than 1.1 million persons are living with HIV/AIDS in the United States, [105] and it disproportionately impacts African Americans. [106] Hepatitis B is also considered a sexually transmitted disease because it can be spread through sexual contact. [107] The highest rates are found in Asia and Africa and lower rates are in the Americas and Europe. [108] Approximately two billion people worldwide have been infected with the hepatitis B virus. [109]

The first well-recorded European outbreak of what is now known as syphilis occurred in 1494 when it broke out among French troops besieging Naples in the Italian War of 1494–98. [110] The disease may have originated from the Columbian Exchange. [111] From Naples, the disease swept across Europe, killing more than five million people. [112] As Jared Diamond describes it, "[W]hen syphilis was first definitely recorded in Europe in 1495, its pustules often covered the body from the head to the knees, caused flesh to fall from people's faces, and led to death within a few months," rendering it far more fatal than it is today. Diamond concludes,"[B]y 1546, the disease had evolved into the disease with the symptoms so well known to us today." [113] Gonorrhoeae is recorded at least up to 700 years ago and associated with a district in Paris formerly known as "Le Clapiers". This is where the prostitutes were to be found at that time. [86]

Prior to the invention of modern medicines, sexually transmitted diseases were generally incurable, and treatment was limited to treating the symptoms of the disease. The first voluntary hospital for venereal diseases was founded in 1746 at London Lock Hospital. [114] Treatment was not always voluntary: in the second half of the 19th century, the Contagious Diseases Acts were used to arrest suspected prostitutes. In 1924, a number of states concluded the Brussels Agreement, whereby states agreed to provide free or low-cost medical treatment at ports for merchant seamen with venereal diseases. A proponent of these approaches was Dr. Nora Wattie, OBE, Venereal Diseases Officer in Glasgow from 1929, encouraged contact tracing and volunteering for treatment, rather than the prevailing more judgemental view and published her own research on improving sex education and maternity care. [115]

The first effective treatment for a sexually transmitted disease was salvarsan, a treatment for syphilis. With the discovery of antibiotics, a large number of sexually transmitted diseases became easily curable, and this, combined with effective public health campaigns against STIs, led to a public perception during the 1960s and 1970s that they have ceased to be a serious medical threat. [ citation needed ]

During this period, the importance of contact tracing in treating STIs was recognized. By tracing the sexual partners of infected individuals, testing them for infection, treating the infected and tracing their contacts in turn, STI clinics could effectively suppress infections in the general population. [ citation needed ]

In the 1980s, first genital herpes and then AIDS emerged into the public consciousness as sexually transmitted diseases that could not be cured by modern medicine. AIDS in particular has a long asymptomatic period—during which time HIV (the human immunodeficiency virus, which causes AIDS) can replicate and the disease can be transmitted to others—followed by a symptomatic period, which leads rapidly to death unless treated. HIV/AIDS entered the United States from Haiti in about 1969. [116] Recognition that AIDS threatened a global pandemic led to public information campaigns and the development of treatments that allow AIDS to be managed by suppressing the replication of HIV for as long as possible. Contact tracing continues to be an important measure, even when diseases are incurable, as it helps to contain infection.

Coronavirus can still pass between face mask wearers — even when they're 4 feet apart: study

According to a new study, coronavirus can still pass between face mask wearers, even when they are four feet apart.

COVID-19 can be transmitted between people who are standing more than four feet apart, even if they are wearing a mask, a new study has found.

The research, published in Physics of Fluids, notes that face coverings alone do not prevent droplets of fluid that are projected by a cough, a discovery the researchers called "alarming." It adds to the importance to also maintain proper social distancing measures, they said.

The same researchers found previously that droplets of saliva can travel 18 feet in five seconds when an unmasked person coughs, so masks are important. However, repeated coughs are likely to reduce their effectiveness, the experts found in the new study, using computer models.

Corona virus prevention face mask protection N95 masks and medical surgical masks at home . (iStock)

"The use of a mask will not provide complete protection," study co-author and University of Nicosia professor Dimitris Drikakis said in a statement. "Therefore, social distancing remains essential."

If a person has a coughing fit, "many droplets penetrate the mask shield and some saliva droplet disease-carrier particles can travel more than 1.2 meters (4 feet)," Drikakis added.

The calculations from the simulation also noted that droplet size could be affected due to hitting the mask, escaping and eventually, entering the environment.

"The droplet sizes change and fluctuate continuously during cough cycles as a result of several interactions with the mask and face," Drikakis explained.

"Masks decrease the droplet accumulation during repeated cough cycles," Dr. Talib Dbouk, the study's co-author, added. "However, it remains unclear whether large droplets or small ones are more infectious."

The study's findings have implications for health care workers, who are often unable to maintain proper social distancing.

The researchers suggested wearing "much more complete personal protective equipment," including helmets with built-in air filters, face shields, disposable gowns and two sets of gloves.

Earlier this month, the World Health Organization updated its guidance to recommend that governments around the world encourage the widespread use of fabric face masks while in public settings.

Initially, the WHO advised only those who are experiencing symptoms of COVID-19 or are caring for someone infected with the novel virus to wear a face mask. The WHO’s new recommendations also lag behind those from other top health agencies, such as the Centers for Disease Control and Prevention (CDC).

In April, the CDC updated its guidelines to recommend all Americans wear cloth face coverings while in public, “especially in areas of significant community-based transmission."

Disrupting viral replication

Another way plants can defend themselves against viral infection is through the accumulation of mutations in proteins targeted by viral pathogens. For example, research in the 1990s showed that the viral protein VPg interacts with plant proteins in the eIF4E family of translation initiation factors to produce other proteins critical for viral replication. In 2002, a research team in France showed that naturally occurring resistance to several viruses in peppers (Capsicum annum) was caused by a mutation that gave one eIF4E protein a slightly different molecular structure. 7 At the same time, an overlapping group of researchers identified a mutant line of the plant model organism Arabidopsis thaliana in which the gene for an isoform of eIF4E was disabled, leaving normal plant growth unaffected but hampering viral replication. 8 More recently, researchers at the University of Tokyo in Japan identified variants of the nCBP protein, part of the eIF4E family, in Arabidopsis that prevent the accumulation of certain movement proteins, trapping the Plantago asiatica mosaic virus in a single plant cell and saving the whole plant from infection. 9

CHURNING OUT VIRUSES: Once inside a plant, viruses direct the production of compartments known as virus replication factories (green) to make copies of their genomes. Here, leaf trichomes are shown infected by turnip mosaic virus. ROMAIN GRANGEON

HIJACKED BY THE ENEMY: Cross-section of stem infected by turnip mosaic virus virus replication factories stained in green, cell walls stained in magenta. JUANE WAN Plant breeders have long been making use of such naturally occurring genetic resistance, selectively crossing wild varieties to produce more-resistant crops. For example, in the 1980s, work led by scientists at the International Institute of Tropical Agriculture succeeded in breeding partial resistance to the geminivirus-caused cassava mosaic disease—resistance that’s found in closely related wild species of the root vegetable—into cultivated varieties across Africa. 10 By cross-breeding cultivated cassava (Manihot esculenta) with its wild relative, tree cassava (M. glaziovii), the team was able to introduce naturally occurring resistance to the disease, controlled by multiple genes.

Such traditional breeding approaches can take decades, however—a cumbersome prospect when new resistance genes must be introduced for each new viral strain that evolves. More recently, scientists have used genetic engineering techniques to more swiftly and precisely arm crops with such resistance. “Genome editing has just completely revolutionized every part of biology,” says Bart.

Last year, doing screens in yeast, Bart and her collaborators identified two eIF4E proteins from cassava that interact with CBSV and UCBSV VPg proteins. Then, using the CRISPR-Cas9 system, they edited the sequence of those genes to prevent their expression, resulting in a cassava variety that showed improved resistance to the viruses in greenhouse trials. 11 The CRISPRed cassava plants weren’t fully resistant, however, suggesting that the viruses may also be able to interact with the three remaining unedited eIF4E proteins. The team hopes to fine-tune the system to engineer a fully resistant cassava plant.

Recent studies have revealed other tricks used by plants to fight off viral infections. For instance, the process designed to recycle damaged or unwanted objects in the cell—autophagy—has been coopted to remove viral particles, too. Working with tomato plants (Solanum lycopersicum), Yakupjan Haxim at Tsinghua University in Beijing, China, and colleagues found that the plant’s autophagy protein ATG8 binds the viral ßC1 gene, which encodes an essential protein for infection by geminiviruses, transporting it to an autophagosome for degradation. 12 Viruses carrying a mutated version of ßC1, which cannot be bound by ATG8, cause more-severe symptoms and replicate more rapidly. Conversely, when the researchers promoted autophagy—by preventing the expression of enzymes that inhibit the process—plants of the model organism Nicotiana benthamiana, a close relative of tobacco, showed more resistance to three geminiviruses: cotton leaf curl Multan virus, tomato yellow leaf curl virus, and tomato yellow leaf curl China virus.

We have a long way to go to develop sustainable and environmentally sound approaches to really control virus dis­eases. —Bryce Falk, University of California, Davis

As researchers continue to learn more about the natural defenses plants use to protect themselves against viral pathogens, and as they enlist rapidly advancing genetic engineering techniques to equip plants with such weaponry, the field is on its way to having the tools it needs to develop a new generation of resistant crops. But it will be an uphill battle. Viruses are constantly evolving, many times faster than the plants they infect, and it is only a matter of time before each virus develops a countermeasure to such resistance mechanisms. For example, many viruses manufacture a protein that can mop up siRNAs, binding them before Dicer-like enzymes can form a RISC complex and potyviruses such as tobacco vein mottling virus have mutated their VPg protein, allowing them to bind to the modified eIF4E proteins that previously offered the plant resistance.

“I think we have a long way to go to develop sustainable and environmentally sound approaches to really control virus diseases,” says Bryce Falk, a plant pathologist at the University of California, Davis.


We are indebted to J. Luban (University of Geneva, Switzerland) for unwavering support to the first author throughout the course of this work. We wish to thank O. Petrini and M. Tonolla (Istituto Cantonale di Microbiologia, Bellinzona, Switzerland) for active hospitality and encouragement. We are grateful to J. Luban, K. Mullin and M. Eisenstein for critical reviewing of the manuscript. We apologize to those colleagues whose primary reference we have not been able to cite owing to space limitations. M.P.R. and C. S.-D.-C. gratefully acknowledge funding they received from the European Commission 7th Framework Programme for Scientific Research (Project number: HEALTH-2007-2.3.2, GA number: HEALTH-F3-2008-201,032 to C. S.-D.-C.) from the National Institutes of Health (R01 GM062427 and R01 GM071329 to M. P. R.) and the American Cancer Society (RSG0404251 to M. P. R. and C. S.-D.-C.).

Measuring sweat in wearable biosensing devices

When people sweat, they unknowingly release a wide range of chemicals that can noninvasively inform clinicians on anything from stress hormone levels to glucose. But it's hard for researchers to glean this information -- unless you sweat a lot. Emerging wearable devices using stimulant gels have provided a way to induce sweat locally on the body. However, sweat can dilute these gels, which degrades their long-term viability.

An international team of researchers recently developed a new membrane that mitigates both issues that arise from direct dermal contact and sweat dilution for sweat biosensors. As discussed in Biomicrofluidics, by AIP Publishing, the membrane performs hundreds of times better than other methods and holds up to repeated use.

"Everyday use of sweat biosensing is on the horizon, but first we need to work out a few problems, including how to obtain useful samples when patients aren't exerting themselves," said Phillip Simmers, an author on the paper. "Controlled dosing is very important to the medical community."

Iontophoretic devices -- which would draw on the team's membrane -- work by applying a small voltage across the skin to guide a charged drug through the epidermis. Most sweat stimulation devices use a stimulant that is dissolved into a hydrogel at high concentrations to make sure the dosing can be maintained.

While stimulants such as carbachol are useful because the body slowly metabolizes them, they cannot specifically target sweat glands and pose potential risk if an additional stimulant enters the body. When the stimulant activates sweat production, the resulting mélange of hydrogel and sweat not only makes it difficult for the stimulant to reach the skin, but also for the biosensor to accurately read the sweat.

"One of the biggest challenges was that when we sweat, we're actively losing analytes to the gel, which is an issue that hasn't been addressed," Simmers said.

Simmers and his team first constructed an in vitro model to determine which commercially available filtration membranes were best suited for limiting the passive diffusion of carbachol. They found that the best membranes had nanoscale pores and retained more than 90 percent of their initial stimulant concentration after 24 hours, while allowing only a minimal amount of sweat to pass through.

The group then ported this technology to dime-sized adhesive patches and tested them on patients. Using bromophenol blue dye and silicone oil that changes color in the presence of sweat, they were able to confirm that the nanoscale pores identified earlier during their in vitro experiments could still deliver controlled dosing that induced the human sweat response, proving that the membrane was effectively isolating the sweat from the stimulant.

Next up, the group hopes to incorporate their findings into a wearable biosensing prototype that they have already developed. Simmers said he hopes the paper's findings will also stoke interest in how to better produce membrane materials for such devices.

How one SARS-CoV-2 protein keeps cells from fighting back

Findings may explain why people can produce high levels of the coronavirus and spread infection before symptoms appear.

New research has uncovered a way SARS coronaviruses delay an immune defense against them. The coronavirus responsible for the SARS outbreak of 2003 and the one causing the current pandemic may prevent cells from responding to infection in a similar manner. They do this by making a viral protein that keeps molecules from moving through pores in the membrane that separates a cell nucleus from the surrounding cytoplasm.

“With these pores blocked, infected cells can’t fight back,” said Dr. Alex Greninger, assistant professor of laboratory medicine and pathology at the University of Washington School of Medicine, who led the study. “Eventually, the cells are able to respond and mount a response, but the action of this protein gives the virus time to replicate and generate a large viral load.”

The findings may explain why people infected with COVD-19 can produce very high levels of the virus and spread the infection before they develop symptoms. Such asymptomatic transmission is thought to be a major reason the virus spreads so quickly through communities.

The nucleus, the cell’s command center, is surrounded by a membrane that separates it from the rest of the cell. To enter or leave the nucleus, molecules must pass through tunnel-like structures, called nuclear pore complexes, that traverse the membrane. This process, called nucleocytoplasmic transport, is highly regulated.

In the new study, the researchers looked at how a viral protein called ORF6 affects this process. ORF6 is one of five or six “accessory” proteins made by SARS-CoV and SARS-CoV-2.

“They’re called ‘accessory’ because they are not needed for the for the virus to replicate in a laboratory dish,” Greninger said, “but they can contribute to the pathogenicity of the virus by inhibiting the innate immune response to the virus.” SARS coronaviruses are unique in having significantly more accessory proteins than the four seasonal human coronaviruses, which generally cause infections every winter.

The researchers’ report appears in the American Society for Microbiology’s journal mBio. Amin Addetia, a first-year graduate student in the UW Molecular and Cellular Biology Graduate Program, was the paper’s lead author.

In a series of experiments, members of Greninger’s lab worked with the lab of Michael Gale, Jr., University of Washington School of Medicine professor of immunology and director of the Center for Innate Immunity and Immune Disease. This research showed that ORF6 inhibits infected cells’ ability to produce proteins needed to respond to infection. Normally, to synthesize a protein, a gene in the nucleus must be activated and the instructions encoded in the gene’s DNA must be converted to RNA. This RNA, called messenger RNA, or mRNA, must then be transported out of the nucleus to molecular machines in the cytoplasm, called ribosomes, that “read” the mRNA and begin assembling the protein.

As part of this process, two proteins, an mRNA export factor called Ribonucleic Acid Export 1 (Rae1), and a nuclear pore complex protein, called (Nup98), play a key role by binding together with the newly synthesized mRNA and shepherding it through the nuclear membrane pore

“It’s as though they hold mRNA by the hand and ‘walk’ it through the pore,” Greninger said.

However, when cells were infected with SARS-CoV or SARS-CoV-2, the researchers found that ORF6 bound to and disabled the Rae1-Nup98 complex. This counterdefense trapped mRNA in the nucleus so that it could not reach the ribosomes in the cytoplasm. This limited the ability of the cell to make new proteins to combat the infection.

The researchers also found that ORF6 prevents a broad range signaling proteins from entering the nucleus. These include signaling proteins that help orchestrate the cell’s response to infection.

“Basically, ORF6 clogs up the nuclear pore, preventing both nuclear import and export, rendering infected cells incapable of responding to infection,” Addetia said. “The viral genes replicate entirely in the cytoplasm. The virus doesn’t need the nucleus, so blocking the nuclear pore with a small protein is a simple way of shutting down the host response.”

In particular, the ORF6’s blockade of the nuclear pore complexes prevents infected cells from responding to and producing antiviral proteins. This limits their ability to generate a group of proteins called interferons, so called because they interfere with viral replication. Interferons have widespread effects, including triggering immune responses that are responsible for such symptoms of infection as fever, chills and fatigue.

“The ability to block interferon is important because it allows the virus to replicate rapidly before you have symptoms, when you’re still likely to be out and about in the community and able to transmit the virus to others,” Greninger said.

The findings underscore the importance of gaining a better understanding the role of the SARS-CoV-2 accessory proteins, according to Greninger.

“A lot of attention has been focused on the virus’s spike protein, but these accessory proteins are another reason SARS-CoV-2 is so dangerous,” he said. “We need to understand what every single protein produced by these viruses does.”

This work was supported by a Department of Defense contract (W81XWH-20-1-0270) and grants from the National Institutes of Health (AI118916, AI127463, AI143265, AI145269, S10 OD016240).

Infrared Sauna

Warm up to better health! Infrared saunas enhance our well-being on many levels by using the same gentle rays as natural sunlight. They also provide therapeutic benefits of traditional saunas without the intense heat. A great way to relax and get healthy!

Infrared saunas heat the body directly instead of the air by duplicating the healthy warming rays of the sun. These rays are transmitted deep into the body while maintaining a comfortable temperature that does not overheat the skin and respiratory system like traditional saunas. This means that you can enjoy the benefits longer.

Infrared Sauna Therapy:

Supports detox
Heat causes our cells to release toxins into our lymphatic system. The sweating induced by this deep warming removes them from the body as our sweat is largely manufactured from lymphatic fluids. As toxins pass through the skin the workload on our liver and kidneys for detoxification is reduced.

Clears and cleans skin
Increased circulation and sweating stimulated by the heat pushes imbedded toxins out through previously blocked pores. Old and dead skin cells are released leaving the skin clean and refreshed. The sweating out of acid wastes also alleviates acne, eczema and psoriasis while improving skin tone and elasticity, and providing a healthy glow.

Enhances weight loss
As our body increases sweat production to cool itself our heart rate rises to pump blood and increase circulation. This burns calories in addition to the water lost as sweat. While the water should be replaced by drinking plenty of fluids, the calories will not, helping us lose weight. The increase in heat also helps break down pockets of cellulite.

Supports cardiovascular health
The increase in heart rate conditions our heart, while our diastolic blood pressure drops as our blood vessels dilate. NASA has determined that infrared saunas may be useful in maintaining astronauts’ fitness during long periods in space, when other forms of exercise are difficult to perform.

Relieves pain
Dilation and relaxation of blood vessels, detoxification and muscular relaxation also facilitate a reduction in the pain response. One element of our feeling discomfort is how our body responds to any given stimulus. Infrared saunas assist in relaxing and dampening any reaction to these stimuli, reducing pain.

Boosts immune system
Infrared saunas have been shown to improve our immune response by stimulating an increase in the number of white blood cells. The rise in body temperature also mimics fever which supports our body’s attack on foreign bacteria and viruses.

Enhances performance levels
Infrared heat warms and promotes the relaxation of muscles. Using an infrared sauna before and after events improves warm ups, prevents injury and helps to decrease and remove lactic acid – a product of intense exercise. Using the sauna at any time enhances training results and recovery.

Enjoying an infrared sauna until you sweat, as frequently as possible, will enhance detox, while improving weight loss, clearing complexion and strengthening immunity. Spend some time warming yourself up to glowing inner and outer health.

How sweat helps

Most detoxing happens through the liver and kidneys, but when the amount exceeds the capacity the body can handle, Dr. Morrison says, your pores will start to pitch in. “There&rsquos only so much they [the liver and kidneys] can grab and package. If there&rsquos more coming in, then the body has to manage it. That&rsquos when the body starts trying to sweat things out.”

Research backs up the point, he says, with multiple studies that have shown heavy metals like arsenic, lead, and mercury in sweat after exercise (and saunas). “They also know that there are some fat soluble toxins in the sweat as well. Just like you can absorb them through the skin, you can also pass them back through it.” Think endocrine disruptors like BPA (learn more about those here).

Most detoxing happens through the liver and kidneys, but when the amount exceeds what the body can handle, your pores will pitch in.

Which brings him to an important piece of advice: If you’re looking to use your spin session or Bikram Yoga class as a detox opportunity, you’ve got to ditch the currently trendy “wear your sweaty athleisure all day!” mentality.

“The next step is soap and water in the shower. The soap will help carry away the fat soluble toxins,” Dr. Morrison says. “If you don&rsquot, they&rsquore just going to get reabsorbed through the skin, and all that hard work was for nothing.” When it comes to detoxing, at least.

Too. much. sweat. Try these 9 natural deodorants that are good enough for your intense workouts.