What You Should Know About Giardia & Giardiasis
The Centers for Disease Control and Prevention reports that in the US Giardia infects over 2.5 million people annually.
Symptoms usually begin 1 to 2 weeks (average 7 days) after an individual becomes infected. In otherwise healthy individuals, symptoms may last 2 to 6 weeks. Though symptoms may last longer, medications can help decrease the duration of symptoms.
Giardia has no vector. It affects a wide range of human and mammalian reservoir hosts. Small aquatic or semi-aquatic wild mammals, such as beavers, muskrats, and small rodents harbor water-born cysts of giardia and serve as important reservoir hosts. Furthermore, a variety of birds may also serve as reservoirs of giardia.
Contaminated water supplies, such as water in rivers and lakes and improperly treated water in developing countries, are also reservoirs of the waterborne cysts. Often, contamination of surface water is caused by rain and wind carrying cysts from fields containing or fertilized by manures of infected humans, livestock, or wild animals to nearby rivers and streams. Giardia cysts can remain viable in surface water for approximately two months. As a result, it is more dangerous for hikers to consume water from rivers and lakes during and immediately after raining seasons as contamination tend to be most severe during these periods. Finally, the organism can often be found in soil, food, and surfaces contaminated with feces containing infectious cysts.
First and foremost, avoid contaminated water. Hikers and overseas travelers to developing countries should consider all water sources contaminated and thus boil, filter, or treat all water with halogenated tablets or solutions. Second, avoid foods washed in contaminated water or that cannot be cooked or peeled, which is especially important for travelers to developing countries. Using only bottled water and avoiding raw fruits and vegetables decreases risk of infection dramatically.
In the United States, many of the reported cases of Giardia occur in the summer months. According to virologists and epidemiologists, this is the time when hikers and backpackers are avid because of the ideal climate during these months. Also, this may be due to the use of community swimming areas by young diaper-aged children during the summer.
Currently, there is no vaccine to protect humans from acquiring giardiasis. Preventing Giardia can be accomplished by practicing good hygiene, purifying/filter water that may be contaminated or avoiding it all together, and avoiding fecal contact.
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