An Approach to preventing Zoonoses in travelers and other groups

Many common infectious diseases are zoonoses in that they are acquired through contact with wild animals, either through direct exposure or via pets or domestic livestock.

Infectious although sometimes rare and unusual zoonoses are not completely random or unpredictable. Humans can decrease their chance of exposure through good hygiene and observation of reasonable precautions.

Understanding of Zoonoses

Zoonoses as diseases are maintained in the wild through a number of mechanisms and understanding this help people recognize their risks.

•  Diseases shared with animals through an abiotic reservoir .

   This includes examples of spore diseases that may lie dormant and infect both   animals and humans (Blastomycosis, Aspergillus).

•  Diseases where the wild animal is the main reservoir

   (rabies in wild foxes and skunks in North America).

•  Diseases transmitted from wild to domestic animals then to people

(rabies from a wild skunk to household dog, plague from exposure to rodents).

•  Diseases maintained in both domesticated and wild animals

  (Mycobacterium bovis).

•  Zoonoses where humans are the main host

  (Mycobacterium tuberculosis, Staphylococcus areas).

•  Disease shared by wild and domestic animals

  (Influenza A, Lyme disease and West Nile virus). Humans as one other animal of   course may also be infected.

•  Disease maintained by domestic animals but occasionally spill into wild animals but are not maintained in those wild animals

  (some examples of mycobacterium bovis that are maintained among cattle but   periodically affect other ungulates).

Generally infectious agents do affect different species differently.

The SARS scare is one example of a zoonoses that emerged quite suddenly and had dramatic consequences for our species.

Avoiding Zoonoses Disease

People working with or exposed to wild animals should be aware of the existence of zoonoses disease. This applies as well to travelers who in the course of their travels may encounter both wild and domestic animals in countries with poor veterinary care.

Know what disease occurs in which species as well as their habitat .

This is relevant for field researchers working on specific animals closely. A literature search or consultation with a veterinarian or wild health specialist can assist prospective students in preparing for their mission.

Use protective clothing when appropriate .

Rubber or vinyl gloves should always be used for handling animal feces, tissue, blood or carcasses. If clothing is likely to be soaked then outer protective lab coat or outer clothing should be worn.

Never let a wild or umkown animal scratch or bite you.

Although obvious, this is especially important for exposure to less threatening "small animals" such as bats or mice.

Avoid animals that are acting abnormally .

Most diseases that affect the central nervous system causing erratic behavior are Zoonoses. Rabies may cause both furious and docile behavior in different species and should always be kept in mind.

Treat all dead animals with respect and rubber gloves should be worn at all times . Dead animals may provide useful information about disease epidemiology (dead crows are used as sentinel cases for the presence of West Nile virus). If appropriate, send dead animal bodies to local authorities but handle with gloves. Small bodies may be put into plastic bags with care to prevent spill or leakage. Contaminated equipment must be cleaned.

Avoid contact with abnormal skin on wild animals .

Diseases such as mange, contagious ecthyma and fungal infection may be passed to humans.

Avoid contact with animals' feces especially those of carnivores .

Parasitic eggs are passed and infective even on cages, equipment or inanimate objects. Many parasites use carnivores as part of their life cycle (intermediate host) and are likely to be very infective so that fomites must be thoroughly cleaned if contaminated.

Avoid all rodents as they carry a large amount of infectious diseases .

Excretions and secretions, nest materials and ectoparasites are all potentially contagious.

Seek medical advice early.

If exposed to Zoonoses people should consult an expert familiar with the animal in question. Physicians may require help from a veterinarian authority to guide correct testing.

Caring for pets and domestic livestock

Pet owners protect themselves by immunizing their pets and keeping them healthy. Although unusual, cases of human heartworm have occurred after kissing household cats. The worm which finds humans a dead end host dies inside the lung but causes a condition identical to a pulmonary embolism.

Protecting pets from impact with wild animals also reduces transmission of disease. For the majority of instances where people are exposed to unknown animals, simple prudence and use of adequate barriers will keep them healthy.

Remember that humans are another legitimate "animal" sharing the environment and equally susceptible to perturbations in it. Of all the factors affecting wild animals, human activity either direct or indirect has the most influence on wild animal health.

Reference:

Essentials of disease in wild Animals by Gary A Wobeser DVA Blackwell Publishing 2006