Microbiological Field Hazards
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:The Wildlife Professional, 1(4):30-35, winter 2007
http://www.wildlifejournals.org
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
https://wwwnc.cdc.gov/eid/article/13/9/pdfs/07-0445.pdf
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 (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) |
| 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 http://www.phac-aspc.gc.ca/id-mi/lyme-fs-eng.php Canadian National Occupational Health & Safety site http://www.ccohs.ca/oshanswers/diseases/lyme.html Health Canada https://www.canada.ca/en/public-health/services/diseases/lyme-disease.html Centres for Disease Control http://www.cdc.gov/ncidod/dvbid/Lyme/ |
| 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 |
| Other |
further information is available from Health Canada: |
| 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 |
| Symptoms: |
bubonic plaque: fever, chills |
| Treatment: | antibiotics; can be immunized |
| Other |
Tests confirm Grand Canyon biologist died of plague" - LA Times 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.