Re: Can diseases that transmit via bodily secretions be passed by sweat?

Since this asks about a variety of diseases, it’s best not to expect a one-size-fits-all answer. A good, authoritative source of this kind of information is the Control of Commmunicable Diseases Manual, 18th edition, which was edited by Dr. David L. Heymann and published in 2004 by the American Public Health Association, Washington,DC. Dr. Heymann and many others who participated in the writing and editing are on the staffs of the World Health Organization in Geneva, Switzerland, and the U.S. Centers for Disease Control and Prevention in Atlanta, Georgia. Here’s part of what the book says about transmission of these diseases. Explanatory notes have been added in square brackets [ ].

Acquired Immunodeficiency Syndrome (AIDS): “Mode of transmission—Person to person transmission through unprotected (heterosexual or homosexual) intercourse; contact of abraded skin or mucosa [mucous membranes] with body secretions such as blood, CSF [cerebrospinal fluid] or semen; the use of HIV[human immunodeficiency virus]-contaminated needles and syringes, including sharing by intravenous drug users; transfusion of infected blood or its components; and the transplantation of HIV-infected tissues or organs.” [further along] “While the virus has occasionally been found in saliva, tears, urine and bronchial secretions, transmission after contact with these secretions has not been reported.” [nothing about sweat]

[Hepatitis: There are five kinds of viral hepatitis that affect humans. Although they are conveniently named A, B, C, D (or Delta), and E, they are caused by quite different viruses and are transmitted in various ways.]

Hepatitis A: “Mode of transmission—Person to person by the fecal-oral route.” [Tells about outbreaks from water and food contaminated with human feces—nothing about sweat]

Hepatitis B: “Mode of transmission—Body substances capable of transmitting HBV include: blood and blood products; saliva (although no outbreaks of HBV infection due to saliva alone have been documented); cerebrospinal fluid; peritoneal [in the abdomen], pleural [in the chest cavity], pericardial [in the heart sac] and synovial [in the joints] fluid; amniotic fluid [surrounds the baby before birth]; semen and vaginal secretions and any other body fluid containing blood; and unfixed [not treated with formaldehyde] tissues and organs.” [further along] “Major modes of HBV transmission include sexual or close household contact [This last is later said usually to be among children.] with an infected person, perinatal [associated with childbirth] mother-to-infant transmission, injecting drug use and nosocomial [in a hospital or clinic; transfusion, hemodialysis, acupuncture, accidental needle stick, etc.] exposure.”

Hepatitis C: “Mode of transmission—HCV is primarily transmitted parenterally [by routes other than the digestive tract; usually transfusion of blood from an infected person or injection with a shared needle]. Sexual and mother-to-child have been documented but appears far less efficient or frequent than the parenteral route.”

Delta hepatitis: “Mode of transmission—Thought to be similar to that of HBV [this virus only infects people in conjunction with HBV]: exposure to infected blood and serous [like blood serum] body fluids, contaminated needles, syringes and plasma derivatives such as antihemophilic factor, and through sexual transmission. Intrafamily contacts with HBsAg carriers [people who are infected with HBV] are a major risk factor for the spreading of HDV.”

Hepatitis E: “Mode of transmission—Primarily by the fecal-oral route; fecally contaminated drinking water is the most commonly documented vehicle of transmission. Person-to-person transmission probably occurs through the fecal-oral route, although secondary household cases [transmission from an infected person to someone else in the same home] are uncommon during outbreaks. Recent studies suggest that hepatitis E may in fact be a zoonotic infection [transmitted to people from animals—in this case, maybe pigs and deer] with coincident areas of high human infection.” [Of the six diseases considered here, this is the only one that is even suspected of involving any species other than people.]

There are no entries in the book’s index for “sweat,” which suggests that sweat is an unlikely means of transmitting any human infection. However, if the infectious agent is circulating in a person’s blood, any wound that causes blood or serous (tissue) fluid to be shed might disseminate the agent. How it gets into another person is another matter; the descriptions above show that some of these agents infect via the digestive tract (usually with food or water), whereas others are most likely to infect by injection or unprotected sex. Screening of blood donors, to be sure that transfused blood is safe, is a very exacting science. In the poorest countries of the world, where blood is often needed and screening facilities are limited, AIDS, HBV, and HCV are often transmitted by transfusions.

But, as we often say, “No sweat!”

Dean O. Cliver