Giardia at a Glance
There is one particular contaminant that rings through the heads of hikers and outdoorsmen hauntingly, with all fears of ruining their trip--Giardia. This intestinal parasite has a history of bringing scary symptoms to unsuspecting drinkers of surface fresh water. With over forty known species existing in the intestines of vertebrates all over the planet, they are predominantly subsisting all over the surface of soils and waters from fecal matter. The animal waste is moved from rainfall and naturally running water, spreading its contaminants further and further. It is estimated that nearly 20,000,000 Americans are at risk for giardiasis, considering unfiltered drinking water sources [R. L. Mahler, Microbial Contaminants:Giardia]. Nearly 2 out of 10,000 Americans suffer giardiasis every year, and 19.6 out of 100,000 Canadians. Up to 4.6 of the United Kingdom population has been sampled as infected and more than 10 percent of the population of Italy has been infected, making this one of the most widespread contaminant worries in the world [What is the global incidence of giardiasis?].
The life cycle of giardia starts with cysts on contaminated surfaces, be it water, food, etc. It then enters the host’s digestive tract and attaches to the intestine. Each cyst releases two trophozoites in the excystation process, feeding off of the host’s nutrients. After multiplying and increasing the infected area, the process of encystation begins, where trophozoites are then transformed back into cysts. These cysts are found in the stool of the infected, and persist for months in their environment after passing [Pathogen and Environment | Giardia | Parasites]. The below is a figure from the CDC of giardia trophozoites [Home - Public Health Image Library(PHIL)].
The problem of giardia is one of public health concern, being one of the most common intestinal parasites for humans. In contracting giardiasis, one would experience a variety of negative symptoms, namely: diarrhea, stomach pains, weight loss, malnutrition in children, and more. Although these symptoms rarely lead to death in America, the health issue is still notable, as the illness is a considerable burden, often with residual intestinal problems long after the infection is remediated. To be clear, it is a pain in the rear. The disease is also highly contagious, even from human to human, though the method of spreading the infection is not as much of a threat as some viruses are for example. It is thought that consuming only 10 cysts can cause a full blown infection. These statements are reflected in the fact that nearly 98 percent of cases are waterborne, whereas around 2 percent are person to person or food-borne. [Giardia and Water Pathogens Risk for Hikers and Backpackers – Outdoor Adventures] There are cases of immunocompromised populations and their outbreaks of giardia causing significant discomfort and health concerns, but this is not as much of a threat as the microbe cryptosporidium has traditionally been. Looking further demographically, giardiasis affects more males than females marginally, and more children than adults drastically. This could be a result of exposure as well as hygiene practices, but regardless of age or gender, it is a smart idea to relay to a doctor your symptoms if you are at risk of infection as recommended by the Mayo Clinic [Giardia infection (giardiasis) - Symptoms and causes]. After stool samples are analyzed and a case of giardia is confirmed, it is likely one would be prescribed one of the many effective antibiotics, and be ordered to drink more water than normal to reduce chances of dehydration.
Giardia is prevalent in most of the surface water sites that one could imagine, including rivers, glacial lakes, high mountain streams, private wells, and even some swimming pools have been found with abnormally high levels. It has been known to spread from swimming pools to swimmers through urine, fecal matter, sweat, and traces of dirt. A safe way to minimize this, though not a complete preventative measure, is keeping the ph level to the desired accuracy (7.2-7.8), and keeping the chlorination at proper maintenance. Chlorinating at a rate of around 3 mg/L has been known to eliminate the number of cysts present in the water [Facts About Giardia and Swimming Pools]. As for some of the more natural bodies of water, the main source of contracting giardiasis is through the accidental consumption of water while recreating or camping, and the purposeful consumption of water without proper precautions. In regards to accidental consumption while camping, this is somewhat preventable, since a lot of infections are chalked up to poor hygiene practices. If the camper makes sure the water being used for cooking and cleaning is properly treated, whether by boiling, chemically disinfecting, or filtering, they are much less likely to get the pesky parasites. Additionally, the concern of fecal hand contamination is a nasty, yet overlooked issue contributing to the spread of giardia, since in some sample size of hikers even up to 33 percent were shown to carry fecal matter on their hands [American journal of Infection Control High fecal hand contamination among wilderness hikers]. This can be prevented by washing thoroughly with a clean water source. As for the second aspect of the problem, there are a few ways to help prevent an infection. If for some reason, the hiker is without proper means of disinfecting the water source, they should look for a way of retrieving water from the least likely surface water source. Although cases are more commonly found from campers drinking stream water, this does not necessarily mean they are more likely to hold a higher proportion of microbes than ponds. It should be just the opposite, and since the stagnancy of water is actually thought to harbor more microbes. Hence, much of cultural rural knowledge implores hikers to drink from faster rushing streams. It has also been said that getting to higher elevated areas of the stream, in regions where runoff would accumulate less, risk of getting giardia might decrease. If one could somehow obtain water below the surface, or at the direct origin of the stream, perhaps this would lower risk as well. Although these secondary methods are not a sure-fire way to reduce risk, the surety that comes with a good filter (maximum pore size less than 6 microns [R. L. Mahler, Microbial Contaminants:Giardia]) can put any camper at ease.
Considering the reason the parasite is so prevalent in surface water is largely due to its persistence in the intestines of local animals, it should be inspected along the same lines, how animals are affected. One study showed infection rates of cattle in their countries, with the lowest infection rate displayed at 9 percent with a sample size of 467 in Portugal, and the highest infection percentage of 57.8 percent with a sample size of 64 in Canada and Australia [Zoonotic Potential and Molecular Epidemiology of Giardia Species and Giardiasis]. This is a significant issue, when reflecting on the agricultural runoff and its effects on our surface water, and respective recreation. It has been noted that a smart procedure to reduce risk of infection could be washing your vegetables well before consumption [https://medlineplus.gov/giardiainfections.html].
Since it is possible that giardia could exist in one’s well water, especially if the well is more shallow, there could be a few questions of how to determine its prevalence. Penn State University has reported that it is difficult to know exactly to what extent giardia exists in the water supply, since the absence of cysts in a single sample isn’t a completely accurate determination. While it is not as simple and costly as figuring the amount of some more easily recognized
chemical in the drinking water, there are still tests that help determine if a source is contaminated. This process requires sending a sample to analysts, and can cost hundreds of dollars [Removing Giardia Cysts from Drinking Water - Articles Articles].
In light of all this, it should be said that even though Giardia is a threat to public health, there are preventative measures one can take in order to remediate this risk. It is probable that the most efficient way to eliminate risk of giardiasis would be protecting the drinking water source, from animal travel, precipitation runoff, and even humans. If this isn’t possible, in many scenarios, this prevention can be as simple as practicing proper hygiene, from washing one’s hands and plant based foods, to utilizing clean water for camps and making sure cooking materials are properly maintained. Keeping sanitary public swimming practices such as rotating water use every hour and proper PH/chlorination also aids in lowering the risk, as public pools with a high proportion of children can be of concern without these in effect. Though the virus has imposing symptoms after contracting, the infected populace can oftentimes use antibiotics to pacify the infection. At the end of it all, the easiest way to keep from getting giardiasis is to preemptively use caution, but if it is contracted, it is pretty likely that one will live through the pain and go on with their regular day to day life once they are rid of the parasite.
Works Cited
Mahler, R. L. “Microbial Contaminants: Giardia.” Drinking Water and Human Health. 6 Mar. 2021.
Bryan Swistock Senior Extension Associate; Water Resources Coordinator Expertise Water wells. “Removing Giardia Cysts from Drinking Water.” Penn State Extension, 26 Feb. 2021, extension.psu.edu/removing-giardia-cysts-from-drinking-water.
“Giardia Infections.” MedlinePlus, U.S. National Library of Medicine, 29 Sept. 2020, medlineplus.gov/giardiainfections.html.
Feng, Yaoyu, and Lihua Xiao. “Zoonotic Potential and Molecular Epidemiology of Giardia SpeciesandGiardiasis.”ClinicalMicrobiologyReviews, AmericanSocietyforMicrobiology (ASM), Jan. 2011, www.ncbi.nlm.nih.gov/pmc/articles/PMC3021202/.
Dylan S. Kellogg, et al. Www.ajicjournal.org, American Journal of Infection Control, 1 Mar. 2012, adirondoc.com/wp-content/uploads/2016/09/high-fecal-hand-contamination-among-wildern ess-hikers.pdf.
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“Giardia Infection (Giardiasis).” Mayo Clinic, Mayo Foundation for Medical Education and Research, 17 Nov. 2020, www.mayoclinic.org/diseases-conditions/giardia-infection/symptoms-causes/syc-2037278 6.
“Giardia and Water Pathogens Risk for Hikers and Backpackers.” Outdoor Adventures, bucktrack.com/water.html.
“Home - Public Health Image Library(PHIL).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, phil.cdc.gov/.
“Pathogen and Environment.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 26 Feb. 2021, www.cdc.gov/parasites/giardia/pathogen.html.
“What Is the Global Incidence of Giardiasis?” Latest Medical News, Clinical Trials, Guidelines - Today on Medscape, 22 Mar. 2020, www.medscape.com/answers/176718-120626/what-is-the-global-incidence-of-giardiasis.
“Parasites - Giardia.” Kenneth M. Klebanow & Associates | Columbia, Maryland, www.klebanowandassociates.com/Parasites-Giardia.
