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University of Alberta Giardiasis in Alberta Common name giardiasis, beaver fever Scientific name single-celled animal (protozoan), Giardia lamblia (=G. duodenalis, =G. intestinalis) What’s Bugging Wild Critters? Fact sheet #37: Giardiasis Significance Giardia lamblia is a widespread and common intestinal inhabitant of humans. It also readily occurs in pets and livestock, and spills over into wild species. Any of these species can produce stages that are infectious to people. Infections in humans range from mild flu-like disease to more serious longterm illness. Infections in wild species largely go unnoticed. tion in a broad range of habitats, that is, in other species. Transmission Cycle What? Where? How? Giardia spp. passes from one individual to another by direct transfer from faeces to mouth (faecal-oral route). The cycle starts with hardy free-living cysts in the faeces. They can survive a range of temperatures and humidity, and can live for months in cold water or in damp, cool substrates. There are numerous species of Giardia, yet the same species occurs commonly in humans, cattle, horses, sheep, pigs, cats, and dogs throughout the world and also can survive in a variety of wild mammals and some birds. Young animals of all species are more likely to be infected than older individuals. It is likely that all these species share their Giardia cysts with each other! Thus these little animals are a classic example of a generalist species that can find suitable conditions for shelter, food, and reproduc- Transfer of infective cysts often involves water. The risk of cysts occuring in water is highest in situations with high-density human populations, poor hygiene, contamination of natural watersheds, or inadequate treatment of domestic water supplies. Large concentrated livestock operations also increase the risk of cysts in the environment. Microscopic Giardia cysts were found in faeces of ancient humans, and thus this tiny protozoan (one-celled animal) has co-existed with our own species for many thousands of years. Indeed, the two species no doubt evolved side by side (or rather, one inside the other). The first description of Giardia was in 1681 – probably some of the first animals examined with a microscope. Nowadays giardiasis is the most common intestinal disease in people. Once they are eaten with water, food, or faeces, each cyst releases a reproductive form (trophozoite) which attaches to the intestinal wall and multiplies rapidly. Damage associated with trophozoites affects the intestine’s ability to absorb water and nutrients, and increases the movement of cells lining the gut. This often results in excess moisture in the faeces (i.e., diarrhoea!). As the environment in the intestine changes, so does Giardia. As they move down the gut, trophozoites change back to cysts and are passed out with the soggy faeces. Giardiasis in Alberta (Giardia lamblia) Distribution in Alberta Giardia likely occur throughout Alberta. Cysts are commonly found in humans and have been recovered from domestic (including dog, cattle, swine, farmed elk, farmed bison) and wild (beaver, muskrat, various voles and mice) sources in the province. Individual infections in humans are not uncommon. Outbreaks of human giardiasis have occurred in various communities, including Banff, Canmore, Edmonton, and Morley. Importance for Wildlife Management Infections of Giardia spp. are not known to adversely affect wildlife. Wild species seem to live in harmony with these protozoans. of “beaver fever” is a complete misnomer. “People fever” or perhaps “people, pets and livestock fever” would be more accurate, although admittedly not as easy to say! Giardia is of concern to dog and cat breeders as well as livestock producers. Infections can lead to lower weight gain and lower final body weight of infected animals. In addition, these animals can contaminate water sources and thus increase the risk of infection in humans and wildlife. Pets and livestock on backcountry trails, in parks, and on grazing leases in forested areas are of particular concern. Similarly, treatment of waste from intensive livestock operations is essential if further contamination of the environment is to be avoided. Public Significance Public water sources in Alberta are regularly screened for Giardia and any cysts automatically removed during the treatment processes. However, hikers, campers, hunters, fishermen, and canoeists are at risk when using untreated water in the backcountry, and a bout of giardiasis can certainly take the edge off the enjoyment of your trip. While this parasite is extremely common, human outbreaks or serious infections are relatively rare. The majority of cases are asymptomatic (showing no signs of disease), but some people exhibit acute or chronic diarrhoea, abdominal cramps, bloating, dehydration, fatigue, and weight loss. Infections usually run their course in 2-3 weeks. Children are particularly at risk. Most infections result from contamination of watersheds by humans or livestock rather than from wildlife. The common name October 2014 Prevention/Control Giardiasis can be readily avoided. Personal preventative measures include proper disposal of faeces, wise personal hygiene (including food preparation), and protection of public water supplies from contamination with faeces of any species. Boiling kills Giardia cysts. And certain water filtration methods remove most cysts. However, chlorination at concentrations that kill most other organisms in water does NOT kill Giardia cysts. If infection occurs, humans, pets, and livestock can be treated successfully with a variety of drugs. Progress is being made towards a vaccine that could prevent infection in livestock and pets. However, potential transmission from people, livestock and pets to wildlife should be avoided wherever possible. Wildlife diseases in Alberta: esrd.alberta.ca/fish-wildlife/wildlife-diseases/ Giardiasis in Alberta Centers for Disese Control - trophozoites (Giardia lamblia) Summary Giardia is one of the most common parasites in humans around the world, including Alberta. Be sure that you do not add to the problem: properly dispose of all faeces from yourself, your livestock, and your pets. Care should be taken whenever untreated water is used for drinking or even brushing your teeth! Boiling prior to drinking kills all Giardia in the water. Additional Information Parasitic Diseases of Wild Mammals, Second Edition. Edited by William M. Samuel, Margo J. Pybus and A. Alan Kocan. 2001. Chapter 16 – Enteric Protozoans. Alberta Agriculture, Food & Rural Development: cattle -www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/beef11744 dogs -www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex736?opendocument cats - www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex737 Health Canada: www.hc-sc.gc.ca/ewh-semt/pubs/water-eau/giardia_cryptosporidium-eng.php Merck Veterinary Manual Online: www.merckmanuals.com/professional/infectious_diseases/intestinal_protozoa/giardiasis.html?qt=giardia&alt=sh October 2014 Wildlife diseases in Alberta: esrd.alberta.ca/fish-wildlife/wildlife-diseases/