Common Parasites


If there’s one thing that many doctors ridicule, then it’s whenever a patient visits them and starts suggesting that they’re suffering from a parasitic infection. Either they’ll brush aside your concerns and give you a different diagnosis, or they’ll suggest that you’re suffering from a Parasitic Delusion Disorder, in which case your prescription will be to stop looking up your symptoms on the internet.


On the other hand, other physicians are quite up to date with the statistics. They realize how even if you’re living in a developed country, the chances of getting a parasitic infection are alarmingly high. Two of these physicians are Dr. Todd Watts and Dr. Jay Davidson, who wrote an article named Parasites: Types, Symptoms, Tests, and Treatment that describes the incidents of parasitic infections in more detail. Following up on their informative explanation, other doctors will be able to offer the right diagnosis and follow up — pinpointing the real culprit behind your IBS or autoimmune symptoms.

When it comes to parasitic infections, they can be much more common than anyone would expect. Here’s a list of the most common parasitic infections in both the developed and developing countries.


Giardia intestinalis

Affecting both developed and developing countries at large, Giardia intestinalis results in diarrhea. It also interferes with the body’s ability to absorb different essential nutrients, such as fats and carbohydrates. It can be transmitted either through getting in contact with an infected patient or through direct ingestion of contaminated food or water. 


Entamoeba histolytica

With an estimate of 50 million people infected with amoebiasis, 55,000 of which die every year, Entamoeba histolytica is another widely prevailing parasite in all countries. In fact, amoebiasis is the third leading cause of death worldwide. It’s mostly transmitted by ingesting fecal-contaminated food and water, the result of poor hygiene. The infected person can suffer from diarrhea, abdominal cramps, bloody stools, appetite loss, and fatigue.


Cyclospora cayetanensis

The recent years have witnessed several outbreaks in cyclosporiasis, the disease resulting from a Cyclospora cayetanensis infection. With its mode of transmission being through ingesting contaminated food and drinks, it results in explosive episodes of diarrhea that’s accompanied by loss of appetite, weight loss, cramps, increased gas and bloating, nausea, and fatigue. 


Cryptosporidium spp

As it’s becoming more prevalent in both developed and developing countries, Cyslospora cayetanensis specifically targets AIDS patients and children less than 5 years of age more than others. It also affects the intestinal tract, but it can affect the lungs of the infected patients as well. As a result, its symptoms can range from diarrhea to more severe symptoms in immunocompromised patients, such as malabsorption of nutrients and muscle wasting. Such symptoms can be fatal for these patients. Cryptosporidium can be carried by many animal hosts, as well as human hosts. It’s transmitted by ingesting contaminated food and water, too.


Toxoplasma gondii

Toxoplasma gondii is another leading cause of death in many individuals. This parasite targets the central nervous system, and it can enter the body through eating undercooked meat or through handling the litter of an infected cat. While it’s mostly asymptomatic in most people, others fail to create antibodies against it, which can cause many problems for people with ocular diseases or compromised immune systems. Even more significantly, it can get carried from an infected pregnant mother to her fetus, which is deadly for the unborn child.


Ascaris lumbricoides

Affecting over a billion in developing countries, Ascaris, also known as the roundworm, still works at large. The main mode of infection is through skin contact with infected soils and surfaces, but they can also be ingested. Afterwards, the eggs enter the host and take residence in their lungs, after which they find their way into the intestine. Once they’re in, they can result in symptoms ranging from abdominal discomfort to nausea, vomiting, wheezing, and fever. In some cases, their hosts can suddenly suffer from severe complications that result in death.


Trichuris trichiura

Also known as the whipworm, Trichuris infects over 795 million people worldwide, being more prevalent in developing countries. They target the human intestine, taking residence and giving rise to many intestinal symptoms. These symptoms include bloody diarrhea, pain when defecating, sudden weight loss, nausea, vomiting, abdominal pain, headaches, and an inability to control defecation at times. Individuals can get infected through getting in physical contact with contaminated soil or through ingesting contaminated food. 


Ancylostoma duodenale and Necator americanus

The two are hookworms, and they’re widely prevalent in developing countries living with severe conditions. In fact, together, they infect around 740 million patients, out of which 80 million are in severe conditions.

Ancylostoma duodenale can infect individuals through the skin and oral digestion and can even pass to the fetuses of infected pregnant women. Necator americanus is also known as the New World hookworm, and it can infect humans through their skin when they’re exposed to contaminated soil, feces, or surfaces, and it takes residence in their small intestines.

Their symptoms can remain asymptomatic, making their patients oblivious to their existence. However, if they do strike, they strike terribly. The symptoms can range from internal blood loss through intestinal walls and anemia to malnutrition, all of which can be fatal.


Trichomonas viginalis

Trichomonas viginalis causes one of the most common sexually transmitted diseases known as Trichomoniasis. Most people can have this infection and not realize it’s there, as it’s mainly asymptomatic. However, it can show some symptoms, which can be manifested as a vaginal discharge color or an unpleasant smell, vaginal bleeding or spotting, vaginal burning on urinating, redness or swelling in the genitals, increased frequency in need to urinate, or pain during intercourse. Some research also indicates that it can result in premature labor, or delivering infants with low body weight.

While not every infection presenting as diarrhea is going to be because of a parasite, parasitic infections are much more common than we’ve thought. It certainly doesn’t help that most physicians discard the concerns of their patients regarding the possibility. Many parasites are quite prevalent in both developed and developing countries alike, and proper measures should be taken to spot the cause early on, examine the symptoms, perform the most accurate diagnostic tests, and give the correct treatment.