Microbiological Field Hazards

Some Potential Microbiological Hazards for Field Workers

Field workers should be aware that besides the 'macrobiological' risks associated with working in a field setting (e.g. bears, dogs and wasps), there are also microbiological hazards that could be significant. Workers should consider the animals they deal with and the organisms that may be associated with these animals in evaluating the risk that certain situations may present. Most animals likely contain some disease and some of these can be contracted by humans. The routes of entry into a person include:

1. orally (ingestion): many organisms enter this way. Wear protection; wash your hands before eating, drinking or smoking.
2. skin breaks (cuts, abrasions, animal bites): e.g. tetanus, rabies
3. respiratory route via inhalation (also mucosal membranes): Hantavirus, rabies,

Knowing how the organisms enter allows you to use protective clothing (gloves, eye protection, filter masks) and adopt prudent practices: wash your hands before eating/drinking/smoking; wear insect repellent and wear clothing to minimize exposed skin; and not petting skunks or raccoons.

A list of some microbial agents that include: bacteria, viruses, protozoans and worms and some characteristics of the infection appears below. More detailed technical information may be found in a binder located in the MSDS filing cabinet near CW468 in the Biological Sciences Building. Current information on a wide variety of microbial pathogens can be found at Health Canada web site: Population and Public Health Branch (PPHB) of Health Canada (formerly Laboratory Centre for Disease Control).

Highly Recommended Reading for all Fieldworkers:

Wildlife as Sources of Zoonotic Agents (PDF, 229kb)
Kruse H, Kirkemo A-M, Handeland K. Wildlife as source of zoonotic infections. Emerging Infectious Diseases [serial on the Internet]. 2004 Dec
[downloaded Feb 07, 2005].

This is an exellent article that outlines the variety of agents that one might encounter while hiking and camping out of doors and should be required reading for those actually capturing or handling animals in their research. It mentions a theory that Alexander the Great, who died in 323BC, may have succumbed to a West Nile virus infection (they did not have DEET back then).

Other papers of interest:
Minimizing Infectious Disease Risks in the Field
James N. Mills, Darin S. Carroll, Marcia A. Revelez, Brian R. Amman, Kenneth L. Gage, Sherry Henry, and Russell L. Regnery
The Wildlife Professional, 1(4):30-35, winter 2007
free access to members; others must purchase article

Threat of Hantavirus Pulmonary Syndrome to Field Biologists working with Small Mammals
Douglas A. Kelt, Dirk H. Van Vuren, Mark S. Hafner, Brent J. Danielson, and Marcella J. Kelly
Emerging Infectious Diseases • www.cdc.gov/eid • Vol. 13, No. 9, September 2007

Two cases of Hantavirus Pulmonary Syndrome - West Virginnia, July 2004
One case involved a graduate student who died a month after trapping and handling small mammals including mice. None of the workers consistently wore gloves or washed their hands before eating. The worker was diagnosed with Hantavirus Pulmonary syndrome and tularemia. Index:
tetanus, lockjaw rabies
cryptosporidium West Nile Virus
tularemia Toxoplasmosis
Giardia Plague
Hantavirus Trichnellosis
Listeriosis tapeworms
Lyme disease roundworms
Tapeworm and Roundworm parasites
Prevention Summary
tetanus, lockjaw (bacterium) (go to index)
Agent: Clostridium tetani
Host humans, animals (including farm animals); in feces
Mode Infection: spores enter through wounds (cuts, abrasions) via soil or animal feces contamination; common in agricultural areas
Incubation period: ~ 10 days
Symptoms: endotoxin causes severe muscle contractions of neck and trunk; can be fatal
Treatment: antibiotics
Immunization usually mixed along with diphtheria immunization; lasts ~10 years
cryptosporidiosis (protozoan) (go to index)
Agent: Cryptosporidium parvum
Host humans, poultry, fish, reptile, mammals (small/large) in feces
Mode Infection: Ingestion; fecal-oral route, animal to person, food and waterborne
Incubation period: ~7 days
Symptoms: diarrhea, abdominal cramps, vomiting
Treatment: none
Immunization No
tularemia, rabbit fever, deerfly fever (bacterium) (go to index)
Agent: Francisella tularensis
Host wild rabbit, muskrat, beaver, some domestic animals
Mode Infection: ingestion; handling infected animals, arthropod bites, inhalation
Incubation period: ~3 days
Symptoms: lymph node swelling or pneumonic disease if inhaled; death
Treatment: antibiotics
Immunization available for occupational risk group
Further Information a case of tularemia in Alberta, May 2007
Giardia, Beaver fever (protozoan) (go to index)
Agent: Giardia lamblia
Host humans and animals (wild and domestic)
Mode Infection: ingestion: fecal - oral on hands or via contaminated water
Incubation period: ~ 8 days
Symptoms: none to sudden diarrhea, cramps, fatigue
Treatment: drugs available
Immunization no
Hantavirus (go to index)
Agent: Hantavirus (Sin Nombre virus)
Host field rodents( mice, rats), humans
Mode Infection: inhalation of dust contaminated with feces, urine, saliva
Incubation period: ~14 days
Symptoms: abrupt onset of fever for 5 days; back/abdom pain, headache, vomiting, death
Treatment: drugs
Immunization no
Further Information

1. field researcher death (2004)
2. CDC_Hanta_Prevention
3. CDC_Hanta_transmission
4. CDC_Lab_Guidelines
5. AHS_Hanta_Information

Listeriosis, listerella (bacterium) (go to index)
Agent: Listeria monocytogenes
Host humans, domestic and wild mammals, fowl; via feces or during pregnancy/birth
Mode Infection: ingestion (vegetables, dairy), contact with feces or contaminated soil; handling fetuses possibly inhalation
Incubation period: ~ 7 days
Symptoms: maybe pimple lesions on arms
Treatment: antibiotics
Immunization no
Lyme disease (spirochete) (go to index)
Agent: Borrelia burgdorferi
Host humans, deer, wild rodents
Mode Infection: bite from infected tick
Incubation period: 3-32 days
Symptoms: characteristic skin lesions appearing as red circle, fatigue, fever, headache, later neurological and cardiac abmormalities
Treatment: antibiotics
Immunization yes
Further Information Public health Agency Canada
Canadian National Occupational Health & Safety site
Health Canada
Centres for Disease Control
rabies, hydrophobia (virus) (go to index)
Agent: Rabies virus
Host in animals: dog, cat, fox, wolf, raccoon, sometimes bats
Mode Infection: virus in saliva transmitted via bite, inhalation or mucosal route
Incubation period: ~ 4 weeks
Symptoms: apprehension, headache, fever; spasms, paralysis, delirium, death
Treatment: wash wounds immediately (soap, 70% alcohol)
Immunization available for occupational risk group; series takes at least 1 month
Toxoplasmosis (protozoan) (go to index)
Agent: Toxoplasma gondii
Host cats, other domestic/wild animals, humans
Mode Infection: ingestion of undercooked meat, contam. milk/food/water; soil contam with feces, inhalation of cysts.
Incubation period: ~ 15 days
Symptoms: often none; fever, sore throat, rash; similar to mononucleosis
Treatment: drugs
Immunization no
West Nile Virus (go to index)
Agent: West Nile Virus (Sin nombre virus)
Host mosquito, bird, domestic animals
Mode Infection: mosquito bite
Incubation period: 3 - 12 days
Symptoms: fever, headache, stiff muscles (all range from mild to severe), most people recover but can be fatal
Treatment: treat symptoms and complications of encepahalitis

further information is available from Health Canada:
Biosafety Advisory - West Nile Virus
West Nile Virus Surveillance Information
and the Government of Alberta:
West Nile Virus and Workers

Plague (go to index)
Agent: Yersinia pestis (bacterium)
Host wild rodents (rock squirrels, praire dogs, rats), infected mammals (e.g. feline carnivores)
Mode Infection: transmitted by fleas to humans, direct contact if handling infected tissues/fluids, respiratory droplets from animals / infected humans
Incubation period: 1-6 days

bubonic plaque: fever, chills
septacemic plague: above + bleeding into skin, other organs
pneumonic plague: above + difficulty breathing, rapid shock and death

Treatment: antibiotics; can be immunized

Tests confirm Grand Canyon biologist died of plague" - LA Times
(accessed November 4, 2019)

further infrormation on plague at the CDC website:

Trichnellosis, Trichinosis (intestinal nematode) (go to index)
Agent: Trichinella sp.
Host humans, domestic/wild animals, marine mammals
Mode Infection: ingestion of larvae in undercooked meat (esp pork)
Incubation period: ~ 10 days
Symptoms: muscle soreness/pain; swelling of upper eyelid, gastrointestinal symptoms; cardiac/neurologic complications; death
Treatment: drugs
Immunization no
tapeworms (go to index)
Agent: Echinococcus multilocularis , E. granulosus.
Host foxes, wolves, coyotes, dogs, cats and herbivores like voles, lemmings, shrews, mice, sheep, moose
Mode Infection: ingestion of eggs from fecal contamination of water, food.
Incubation period: months to years
Symptoms: cysts grow over years, symptom depends on where it is growing; blindness, seizures, bone breakage
Treatment: drugs available
Other see additional text: Tapeworms and Roundworms
round worms (go to index)
Agent: Toxocara sp.
Host humans, cat, dog in feces
Mode Infection: ingestion; eggs from contaminated soil or unwashed vegetables
Incubation period: weeks to months
Symptoms: fever or altered vision depending on where the larvae migrate
Treatment: drugs available
Other see additional text: Tapeworms and Roundworms


Tapeworm and Roundworm parasites from contact with carnivores: (go to index)

The following information kindly provided by Dr. Allen Shostak

April 30, 1999

Anyone doing fieldwork with animals should be aware of some parasitic worms that may infect them. It is important to remember that their are many parasites of wildlife that do not normally infect humans but that are perfectly capable of doing so given the opportunity. Most of the infections occur via the fecal-oral route (i.e. eggs from animal feces being transferred into your mouth) so wearing rubber gloves, washing your hands/finger nails thoroughly after contact, possibly wearing protective clothing, avoiding any instances of hand-mouth contact (no smoking, chewing gum, nail biting). The most common source is in handling animal scat and because the eggs are often long-lived, old scat can be just as dangerous as fresh material. Infective eggs may also be present on animal fur although in lesser number than in the scat.

Some possible tapeworm parasites are:
Echinococcus granulosus, Echinococcus multilocularis: adults in carnivores like wolves and coyotes but cysts may occur in Microtines such as voles. Eggs ingested from carnivore scats (and possibly pieces of cysts from mice introduced via a cut) can cause hydatid cysts to form. These are difficult or impossible to treat and can be lethal depending on where they develop in your body.

Some roundworm parasites include:
Toxocara cati, Toxocara canis: carried by many carnivores. Ingested eggs release larvae that migrate aberrantly in the human body.

Trichinella spiralis: can infect most mammals. Serious infections typically arise from consuming under-cooked meat, but handling raw meat might leave enough larvae on your hands to cause an infection by ingestion.

There are certainly many other possible tapeworm and roundworm parasites that field workers handling animals/scats might be exposed to. Infection would most typically be from ingestion of eggs or larvae and less typically via a cut in the skin

Prevention Summary for Microbiological Hazards: (go to index)

Consider the route of entry

1. Oral route: (many of these diseases)

a). contamination on hands from soil or animal contact:

  • wear protection (gloves); overalls, eye protection, particle mask.
  • no eating/drinking/smoking/gum chewing/nail biting until get cleaned up.
  • Wash your hands with soap/water.

b). eating/drinking contaminated food/water:

  • cook food well, wash vegetables
  • don't drink water from streams unless filtered or chemically treated

2. Respiratory Route: (includes mucous membranes): (Hantavirus, rabies, rabbit fever)

  • avoid dusts that may be contaminated
  • wear filter mask (HEPA)
  • disinfect area if must work there (find out what you need: chemical/concentration/time).

3. Skin cut/animal bite: (rabies, rabbit fever, tetanus)

  • wear protective clothing (gloves, boots, coveralls)
  • avoid exposed skin, wear insect repellant
  • don't pet skunks, raccoons, etc.

Consider getting immunized for things like tetanus or other diseases if are engaged in activity that puts you at greater risk.