Category Archives: BioSafety

West Nile Virus


A Field Worker’s Guide to Reduce Exposure

In the coming months, West Nile Virus will be in the news. It is important for Field Workers to learn about any new information concerning this virus – the media can be a good source of information on the spread of WNV across Canada. There are many good web-sites to find information on WNV.

What is WEST NILE Virus?

West Nile Virus is one of a variety of mosquito-borne viruses that can cause infection in humans and animals. The following link offers more information on the West Nile Virus transmission cycle:

What are the symptoms associated with a West Nile Virus Infection?

The WNV normally cycles between mosquitoes and birds. However, if a person or animal is bitten by a WNV-infected mosquito, the virus may be transmitted to them. Most people who are infected with West Nile Virus will not have any type of illness. It is estimated that 20% of the people who become infected will develop West Nile Fever; mild symptoms include fever, headache, body aches, and occasionally skin rash and swollen lymph glands. More severe infection (West Nile encephalitis or meningitis) include headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis and, in rare cases, death. . These severe cases are rare in humans.

How do you catch West Nile Virus?

The most likely route of WNV infection to humans is through the bite of an infected mosquito. WNV may also be transmitted by organ transplantation, blood transfusion, or possibly breast milk. Workers at risk of exposure to WNV include those working outdoors when mosquitoes are actively biting. Occupations at risk include farmers, foresters, landscapers, groundskeepers, painters, roofers, pavers, construction workers, and other outdoor workers. The following web-site offers more information on possible transmission vectors:

Which Animals are infected by West Nile Virus?

Birds of the Corvid family (crows, magpies, ravens, blue jays and grey jays) are susceptible. Surveillance efforts will focus mainly on dead birds which belong to the family known as corvids. Although other bird species in the northeastern United States have become infected with WN virus, experience from the 1999, 2000 and 2001 outbreaks has shown that corvids are the most reliable indicators of WN virus activity and the potential for human infection in an area. The following web-site has more information on vertabrate ecology: Horses are also at risk of infection. The Canadian Food Inspection Agency, in cooperation with veterinarians and other members of the animal health community across the country, will take the lead in monitoring for WN virus infection in horses.

How can you protect yourself from getting West Nile Virus?

One of the best ways to protect yourself is to stay informed. Look up information regarding WNV and keep informed as to where the virus has spread. There are web-links listed at the end of this report.

Many mosquitoes bite people most actively at dusk and dawn. When possible, avoid working outdoors when mosquitoes are biting. Some mosquitoes are active during the day, particularly in weedy, bushy, and wooded or shaded areas. When possible, avoid working in these habitats.

Most mosquitoes are not infected: less than 1% of the mosquito population will carry WNV. The chance that any one bite will be from an infected mosquito is very small. You can reduce your risk of disease by reducing mosquito bites. Precautions that you can follow to help reduce the risk of mosquito bites include:

  • As much as possible try to reduce mosquito-breeding areas by making sure that you have eliminated any pools of standing water in close proximity to the work area. Mosquitoes can reproduce in 4 days if there is standing water available.
  • Wear high top boots, double layers of long pants with the bottoms sealed or taped off or tucked into boots or socks, and a long-sleeved hooded top when outdoors for long periods of time, or when many mosquitoes are most active (between dusk and dawn). Wear gloves to protect the hands.
  • Hats with netting can protect the head and face area and eliminate the need of using mosquito repellent on the face and head areas.
  • Use mosquito repellent according to label directions when outdoors for long periods of time and when mosquitoes are most active.

Insect repellents can be effective at reducing bites from ticks and insects that can transmit disease. But their use is not without risk of health effects, especially if repellents are applied in large amounts or improperly. Most repellent products contain the active ingredients permethrin or DEET. Permethrin-containing products can be used only on clothing, not skin. Permethrin kills ticks and insects that come in contact with treated clothes. Permethrin repellents can cause eye irritation, particularly if label directions have not been followed. Animal studies indicate that permethrin may have some cancer-causing potential. DEET products have occasionally been associated with skin reactions (particularly at concentrations of 50 percent and above) and eye irritation. Under demanding conditions, a two-part approach has been used to protect people from ticks and other biting insects. The approach uses a repellent product containing about 33 percent DEET in a controlled-release formulation on exposed skin along with clothing treated with permethrin. This may meet the needs of individuals spending long periods of time in areas with high populations of active mosquitoes.

The following web site offers important information on the use of insect repellents  Mosquito Spray

When using an insect repellent, use only what and how much you need for your situation; depending on your job, you may need more or less protection. Do not apply insect repellents in enclosed areas. Wash treated clothing separately and wash all treated skin after returning indoors. When using DEET, put it on your hands first, and then apply to your face. DEET can be applied to clothing, but it may damage some synthetic fabrics and plastics. You should wash clothes sprayed with mosquito repellent every day.

Permethrin-treated clothing is effective for two weeks or more; keep treated clothing in a plastic bag when not in use.

If you wear a long-sleeved shirt, long pants, shoes, and socks to reduce the risk of mosquito bites, you may be at greater risk for heat stress on hot, humid days. To avoid symptoms of heat stress, you should wear light-colored, breathable clothing that allows moisture to evaporate quickly and use extra caution if you are required to wear clothing on the job that limits evaporation–you could develop heat stress much more quickly. Also, drink plenty of non-alcoholic and non-caffeinated liquids to maintain body hydration.

DEET (N,N-diethyl-m-touamide or N,N-diethyl-3-methylbenzamide) is the most effective insect repellent available. However, because of health concerns, products containing DEET above 30% will no longer be available to the consumer after December 2004. Studies have shown that products with lower concentrations of DEET are just as effective as the high concentration products, but their effectiveness lasts for shorter periods of time. A product containing:

  • 30% DEET will provide approximately 6.5 hours of protection
  • 15% DEET will provide approximately 5 hours of protection
  • 10% DEET will provide approximately 3 hours of protection
  • 5% DEET will provide approximately 2 hours of protection

Choose the best product for your situation. There are extra precautions when using insect sprays on children and infants and pregnant women. Check the links list above for more information on insect repellents.

The following web sites have information on the West Nile Virus. You should stay informed and keep a close watch on where the virus is known to be present. If you are working in an area where WNV is active, take all precautions to reduce your chance of mosquito bites.

Microbiological Hazards in the Field

­­Most field workers prepare for the macro-biological hazards in the field, but knowledge of the microbiological hazards in the field may be just as important to your health. The table­s below list some of the known microbiological hazards in Western Canada and some that are spreading from south of the border. Early recognition of the symptoms of infections from water-borne or­ arthropod-borne infections could save you from life-threatening illnesses or chronic conditions.

One of the best ways to be prepared for the microbiological hazards is knowing how the bacteria, protozoa, spores, or virus is transmitted and take the appropriate precautions to avoid being contaminated. Once you know the routes of entry for a particular parasite – adopt practices to avoid infections.


Consider the routes of entry:

1. Oral Routes: eg. contamination on hands from soil or rocks:

  • wear gloves to avoid contamination.
  • wear overalls, eye protection or particle masks.
  • do not place your hand near face – no eating, drinking, smoking, chewing gum until you have washed your hands with soap and water.

Another Oral Route is ingesting contaminated food or water:

  • cook food well and wash all vegetables in filtered, chemically treated or boiled water.
  • do not drink lake or stream waters until the water has been filtered, chemically treated or boiled.
  • food must be stored properly while working in the field.

2. Respiratory Routes: Some bacteria or viruses enter the body through inhalation: – eg. Hanta Virus, rabbit fever

  • avoid dusts that may be contaminated.
  • wear an N95 repirator with Hepa filters. Respirator fit tests are required before heading out into the field.
  • disinfect area – find out what you need to use to disinfect the area and know the procedure for disinfection.

3. Open Skin Route: Cuts and abrasions or direct bites: eg. West Nile Virus, Rabies, rabbit fever, tetanus

  • wear protective clothing (gloves, boots, coveralls).
  • protect exposed skin – insect repellent.
  • don’t touch wildlife; dead or alive.

Consider immunization for things like tetanus or other diseases if you are engaged in activities that put you at greater risk.   Routes of Transmission


Tick Prevention:

The following web-link discusses how you should dress to  avoid ticks on the grasses and brush in the areas you are working in. It also shows how to remove a tick if you have been bitten. The prompt removal of ticks can help you to avoid many of the tick borne illnesses listed in the tables below. Always save any tick you have removed in a 70% alcohol solution for later identification.

Check out Alberta’s Lyme Disease and Tick  Surveillance Program site:  Tick prevention in Alberta

Please view the video of how to remove ticks safely:   How to properly remove a Tick

Since some ticks can transmit serious diseases, people should be aware of the symptoms of tick-bourne illnesses.  Many tick-bourne illnesses present with similar signs and symptoms and knowing the differences between the various disease’s symptoms will affect the course of treatment.  Symptoms of Tickbourne Illnesses.


Tick Identification:

Below are some sites that will help you to identify the most common North American ticks.  It is important to keep the tick if you find you have received a tick bite.  The type of tick will help aid in the identification of the illness.

CDC Ticks Information

TickEncounter Resource Center

Tick Identification and How to Repel Ticks and Mosquitoes

Canadian Lyme Disease Foundation


Mosquito Prevention:

West Nile Virus has spread all across North America, it is important to take steps to avoid being bitten by mosquitoes. There are many sites for information on this topic and staying informed is the best way to prevent catching this disease.

The following information may be useful in helping you avoid being bitten by mosquitoes while working in the field:

West Nile Prevention

Another link of interest is this one which describes several serious arthropod-borne viruses that are emerging in North America:

Water Borne Diseases:

It is never wise to drink water from rivers and streams, no matter how clear and clean the water appears. When you are working in the field you need to consider your access to clean water. If there is nothing available you will have to take steps to protect yourself by using a method of water purification. When camping or working in an area of questionable water quality, your drinking water should be boiled for at least 10 to 12 minutes. You can remove many contaminants except bacteria without boiling by using water filters. Always follow manufacturer’s directions and purchase a good quality filter unit to take into the field with you. Know how to use the filter before you leave and purchase additional filter units to have enough on hand.

Another alternative is to have bottled water available at your camp. However, this may not be an option for some remote areas you will be working in.

Other methods for cleaning water include water purification methods such as iodine or chlorine tablets, two methods used to kill water-borne pathogens. The choice of water treatment will depend upon your source of drinking water and the amount you will need.

The following web-link describes how to treat water to ensure it is safe to drink:

Hazards in Western Canada Regions


Name: Lockjaw­, tetanus (bacterium)
Agent: Clostridium teta­ni
Host: Humans, animals (including farm animals) – in feces
Mode of Infection: Spores enter through wounds, (cuts or abrasions) via soil or animal feces contamination; common in agricultural areas
Incubation Period: ~ 10 days
Symptoms: Endotoxins causes severe muscle contractions of neck and trunk; can be fatal
Treatment: Antibiotics­
Immunization: Available – usually mixed along with diptheria immunizations; should be obtained every 10 years.
Further information: US Centre of Disease Control

Name: Cryptosporidiosis (protazoan) or “Crypto”
Agent: Cryptosporidium parvun
Host:; Humans, poultry, fish, reptiles, mammals (small/large) in feces.
Mode of Infection: Ingestion; fecal-oral route, animal to person, food and waterborne.
Incubation period: ~ 7 days
Symptoms: Diarrhea, abdominal cramps, vomiting
Treatment: none
Immunization: None, refer to further information on how to avoid
Further information:

Name: Beaver Fever, Giardia (protazoan)
Agent: Giardia lamblia
Host: Humans and animals (wild and domestic)
Mode of Infection: Ingestion: fecal – oral, on hands or via contaminated water
Incubation period: ~ 1 to 2 weeks
Symptoms: None and then sudden diarrhea, cramps and fatigue
Treatment: Drugs are available
Immunization: No
Further information: US Centre of Disease Control

Name: Listeriosis, listerella (bacterium)
Agent: Listeria monocytogeneis
Host: Humans, domestic and wild mammals, fowl; via feces or during pregnancy/birth
Mode of Infection: Ingestion (vegetables, dairy), contact with feces or contaminated soil, handling fetuses possibly inhalation.
Incubation period: ~ 7 days
Symptoms: Fever, muscle aches, and sometimes gastrintestinal symptoms such as nausea or diarrhea
Treatment: Antibiotics
Immunization: No
Further information:

Name: Toxoplasmosis (protazoan)
Agent: Toxoplasma gondii
Host: Cats, other domestic and wild animals, humans
Mode of Infection: Ingestion of undercooked meat, contaminated milk/food/water, soil contaminated with feces, inhalation of cysts.
Incubation period: ~ 15 days
Symptoms: Often none; fever, sore throat, rash; similar to mononucleosis
Treatment: Drugs
Immunization: No
Further information:

Name: Trichnellosis, Trichinosis (roundworms)
Agent: Trichinella spiraleis, T. psuedospiraleis, T. nativa, T. nelsoni, T. britovi
Host:; Humans, domestic and wild animals, marine mammals
Mode of Infection: Ingestion of larvae, especially in undercooked pork and wild meats
Incubation period: Abdominal symptoms in 2 days, 2 – 8 weeks for systemic reactions
Symptoms: Gastrointestinal symptoms, then muscle soreness/pain; swelling of the upper eyelid, cardiac/neurologic complications; death
Treatment: Drugs
Immunization: None
Further information:

Name: Tapeworms (Avedar Hydatid Disease or AHD)
Agent: Echinococcus multilocularis, E. granulosus.
Host: Foxes, wolves, coyotes, dogs, cats and herbivores like voles, lemmings, shrews, mice, sheep, moose
Mode of Infection: Ingestion of eggs from fecal contamination of water, food.
Incubation period: Cysts grow over years,
Symptoms: Symptoms depend on where the cyst grows; blindness, seizures, bone breakage.
Treatment: Surgery &Drugs
Immunization: See information  at:
Further information:
  2. Medicine

Name: Toxocariasis or Roundworm Infection
Agent: Toxocara canis, Toxocara cati
Host: Humans, cats, dogs; in feces
Mode of Infection: Ingestion: eggs from contaminated soil or unwashed vegetables
Incubation period: Weeks to months
Symptoms: Often none but can be severe. OLM – Ocular larva migrans can lead to blindness, VLM – Visceral larva migrans is the swelling of organs or nervous system. Symptoms of VLM are fever, coughing, asthma or pneumonia.
Treatment: Drugs available if infected; have dogs & cats treated regularly for worms
Immunization: None, see information
Further information:

Name: Rabies, hydrophobia
Agent: Rabies virus (Rhabdoviridae family)
Host: Wild animals such as racoons, skunks, coyotes, wolves, fox, bats, cats and dogs
Mode of Infection: Virus in salivia is transmitted via bites, less often: if saliva gets directly into the eyes, nose, mouth, or a wound.
Incubation period: ~ 4 weeks
Symptoms: Apprehension, headaches, fever, delirium, spasms, paralysis, death
Treatment: Wash wound immediately and treat with 70% alcohol. Always seek medical treatment if you are bitten by a wild animal. Quarantine any domestic animal if it has bitten you in order to watch for signs of rabies.
Immunization: Available for occupational risk group, series takes 1 month.
Further information:
  2. Alberta SRD link

Name: Hanta Virus
Agent: Deer Mouse = Sin Nombre Virus (SNV)
Host: Canada & US: Deer Mouse, Southeast US: Cotton Rat
Mode of Infection: Exposure to an infected rodent’s salavia, urine, droppings or nesting materials. Virus can live for up to a week on dried droppings of mouse.
Incubation period: 1 to 3 weeks and sometimes up to 6 weeks
Symptoms: Fever, headaches, severe muscle aches, possible stomach aches, possible dizziness or chills. 4-5 days later shortness of breath, death. 50% death rate despite medical treatment.
Treatment: Supportive drugs – must seek medical attention
Immunization: None
Further information:
  2. Alberta SRD link

Name: West Nile Virus (WNV)
Agent: Flavivirus
Host: Mosquitoes, birds (over 110 species of birds are known to have been infected with WNV), horses, humans and other domestic animals.
Mode of Infection: Bite of an infected mosquito.
Incubation period: 3 -12 days
Symptoms: Possible no symptoms, some have fever, headaches, stiff muscles (all can range from mild to severe), can progress to encephalitis or meningitis. Can be fatal.
Treatment: Treat symptoms and complications of encephalitis or meningitis.
Immunization: None
Further information:

Name: Tularemia, Rabbit Fever, Deer Fly Fever
Agent: Bacterium: Francisella tularensis
Host: Rabbits, Hares and rodents – widespread in North America
Mode of Infection: Infection to humans is caused by bites of arthropods, commonly ticks and deerflies, or by handling infected animal carcasses or by eating or drinking infected food or water. Bacterium can live in soil or water for weeks.
Incubation period: 3 to 5 days
Symptoms: Early onset of fever, chills, headaches, muscle aches, fatigue, joint pain and a dry cough. Can develop into pneumonia. Can be fatal if left untreated.
Treatment: 10-14 days antibiotics
Immunization: Vaccine available for laboratory workers. Vaccine is under review.
Further information:
  3. Alberta SRD link

Name: Rocky Mountain Spotted Fever
Agent: Bacterium: Rickettsia rickettsii
Host: Hard ticks such as: Dog Tick, Wood Tick and Lone Star Tick. Located throughout US and southern Canada, Central America, Mexico and parts of South America
Mode of Infection: Bitten by an infected tick
Incubation period: 5 to 10 days
Symptoms: Sudden onset of fever, headache & muscle pain followed by a rash. Without treatment can be fatal. With early antibiotic treatment 3-5% cases are still fatal.
Treatment: Treatment with antibiotics early in infection will reduce fatality rate. Remove ticks carefully and keep for identification
Immunization: Vaccine not available – limit exposure to ticks, if bitten – remove tick carefully and keep tick for identification.
Further information:

Name: Colorado Spotted Fever (sometimes called the Saddleback Fever)
Agent: RNA Virus: Arbovirus
Host: Wood Tick (Dermacentor andersoni) Located in Western US, British Columbia and Alberta.
Mode of Infection: Bitten by an infected tick.
Incubation period: 3 – 6 days
Symptoms: Fever for 2 to 3 days, then abates and recurs 1-3 days later for another few days. Headache, fatigue, eye pain & sensitivity to light. Some will develop a rash and some will have stiff neck.
Treatment: Bedrest. Seek medical attention to rule out other tick borne diseases. Remove ticks carefully and keep for identification
Immunization: None
Further information:

Name: Lyme Disease
Agent: Western Black-legged Tick and  Deer tick can carry the bacteria (Ixodes damminie, or Borrelia burgdorferi)
Host: Rodents, deer, rabbits, squirrels, birds. Located throughout the US, British Columbia, southern & eastern Ontario, southeast Quebec, southeastern Manitoba and parts of New Brunswick and Nova Scotia.  Sporatically in other provinces.
Mode of Infection: Bitten by an infected tick.
Incubation period: 3 to 30 days
Symptoms: Can appear as a ring-like rash around the tick bite, flu-like symptoms with fever, chills, aching joints and muscles, fatigue and swollen glands. As Lyme Disease progresses it can cause more serious symptoms such as neurological and muscular problems in some people. Mimics other diseases and can be difficult to diagnose.
Treatment: Antibiotics – attempt to treat in early stages. Remove tick and keep for identification. Later stages are more difficult to treat.
Immunization: Vaccine is available
Further information:
  4. Public Health Agency of Canada
  5. Gov’t of Alberta, Health & Wellness

Name: Relapsing Fever
Agent: Bacterial: Several species of Borrelia spirochete
Host: Body lice in Asia, Africa & Europe or by soft body ticks in the Americas
Mode of Infection: Bite of an infected tick
Incubation period: 3 to 11 days
Symptoms: Chills, head ache, muscle pain and sometimes vomiting. Rash may appear. Fever remains high for 3 to 5 days, then disappears. After 1 –  2 weeks a milder relapse begins & jaundice is common with relapse. The illness will clear again – person can have 2 to 10 relapses at one to two week intervals.
Treatment: Antibiotics
Immunization: None
Further information:


Name: Tick Paralysis
Agent: Neurotoxins present in five species of North American ticks
Host: Engorged pregnant ticks: Rocky Mountain Wood Tick ( Dermacentor andersoni), American Dog Tick ( D. variabilis), Lone Star Tick ( Amblyomma americanum), Black-legged Tick ( Ixodes scapularis) and Western Black-legged Tick ( I. pacificus)
Mode of Infection: Bite from an infected Tick
Incubation period: 2 to 7 days after tick begins to feed. Children will exhibit symptoms sooner.
Symptoms: Begins as weakness in the legs, then progressively ascends until the entire body is paralysed. Once symptoms start to occur, they progress quickly over several hours to days. Symptoms can be only ataxia (loss of co-ordination) without muscle weakness.
Treatment: Locating and removal of the tick. Symptoms will resolve in hours to days. If offending tick is not removed, paralysis can progress to respiratory failure. Remove tick and keep for identification.
Immunization: None
Further information:

Name: Babesiosis
Agent: Cases of Babesiosis have been reported in British Columbia.  Lintraerythrocytic parasitic infection caused by protozoa of the genus Babesia and transmitted through the bite of the Ixodes tick
Host: Deer, blood transfusions
Mode of Infection: Bite of the Ixodus tick, commonly known as the deer tick.
Incubation period: 1 to 4 weeks
Symptoms: Symptoms similar to Maliria – fatigue, anorexia, dark unrine, sensitivity to light, depression, nausea & vomiting, cough, fever, jaundice.
Treatment: Can be treated with Anti-malirial drugs, antibiotics and quinine.  Most cases will improve without treatment. Approximately 25% of the infected cases reported are co-infected with Lyme disease. Note: European Babesiosis 53% of infections are fatal because the infection is caused by a different strain of Babesia in Europe.
Immunization: None
Further information:

Name: Leptospirosis (bacterium)
Agent: Bacterium of the genus Leptospira
Host: Many different kinds of animals carry the bacterium.
Mode of Infection: Exposure to water contaminated with the urine of infected animals. Leptospira organisms have been found in cattle, pigs, horses, dogs, rodents, and wild animals.
Incubation period: 2 days to 4 weeks
Symptoms: Initially begins abruptly with fever and other symptoms. May occur in two phases; after the first phase, with fever, chills, headache, muscle aches, vomiting, or diarrhea, the patient may recover for a time but become ill again. If a second phase occurs, it is more severe; the person may have kidney or liver failure or meningitis. This phase is also called Weil’s disease.
Treatment: Treated with antibiotics, such as doxycycline or penicillin
Immunization: None
Further information:

Name: Baylisascaris Infection or Racoon Roundworm
Agent: Baylisascaris – type of intestinal roundworm
Host: Baylisascaris procyonis is found in Racoon’s intestines.
Mode of Infection: Infection is spread when infective eggs are accidentally ingested by a person or animal
Incubation period: 2 – 4 weeks after ingestion
Symptoms: Depending upon how many eggs have been ingested and where the larvae migrate to will depend upon severity of symptom. Possible death can occur in some cases.
Treatment: No effective, curative treatment is yet available.
Immunization: None.
Further information:
  2. Racoon Roundworm in Canada