I wrote here on parasitic infections generally. But according to the CDC, there are five parasitic diseases on the “Neglected Parasitic Infection” list, worth paying attention to because they are both relatively common, and preventable—though some are more easily treated than others, once contracted.


Perhaps best known as a disease that can cause congenital birth defects in pregnancy, Toxoplasmosis is the T in the acronym TORCH (the O is “other”, R is Rubella, C is Cytomegalovirus, and H is for Herpes infections). Toxoplasmosis birth defects can include mental disability, blindness or hearing loss, but the infection is often asymptomatic in healthy people with strong immune systems. Others may have non-specific symptoms such as fatigue, fever, body aches, headaches, and swollen lymph nodes. Less commonly, eye infections can lead to blindness, or infection in the brain (encephalitis) can trigger seizures.

Cats are carriers, especially if they’ve eaten raw meat. The most common way to contract toxoplasmosis is through contact with cat feces (i.e. from cleaning a litter box.) Like many other parasites, contaminated food or water is also a common method of infection.

The drugs for treatment are fairly nasty, and have to be given for weeks at a time, so it’s best to avoid exposure. You can do this by wearing gloves when cleaning the cat litter box (or when otherwise possibly exposed to cat feces, such as when gardening outside), washing your fruits and veggies thoroughly, and avoiding raw or undercooked meat.

Chagas Disease

Caused by kissing bugs (or triatomine bugs) infected with the parasite Trypanosoma cruzi, Chagas Disease may also be asymptomatic—or it can cause non-specific infectious symptoms like fever, body aches, headaches, and rashes, plus swelling at the spot where the parasite entered the body, or swelling of the eyelids and face. The most concerning complications involve organ enlargement (heart, colon, or esophagus).

Chagas is most common in Latin America, and is most active at night—most people seem to be infected while sleeping, and presumably the bug gets its name because the bites tend to occur on the face. There aren’t known treatments for this — just screening for complications (especially an echocardiogram and EKG to monitor for cardiac complications).

So keep your screens tightly shut, especially while traveling.


This illness is caused by tapeworm larvae that form cysts in various body tissues, especially neural tissue (brain or spinal cord). In lower income countries, they are a common cause of seizures beginning in adulthood. It can also lead to various other neural complications.

Pigs are carriers, and so eating undercooked pork can lead to intestinal tapeworms, but true cysticercosis occurs via fecal-oral transmission from humans. It’s another great reason to wash your hands well, wash your fruits and veggies, and wash your utensils and cutlery. Also, even though there’s an intermediate step, nobody wants intestinal tapeworms either—so make sure pork is thoroughly cooked.

Toxocariasis (Roundworm Infection)

Caused by Toxocara eggs from infected animal feces, these infections also generally come from handling soil or sand. Infections can be asymptomatic, but can also include non-specific infection symptoms (fever, abdominal pain), respiratory symptoms (cough, wheezing), and liver enlargement. It can also infect the eye—usually only one of them at a time, leading to uveitis and decreased vision.

Antiparasitics (which are rather nasty) and steroid therapy are recommended for treatment… but if you have a pet, it’s a good idea to keep them out of play areas for children, keep said areas covered, or again, to wear gloves when gardening or cleaning litter boxes.


Trichomonas vaginalis is a sexually transmitted protozoa, and it is both common and easily cured. It’s often asymptomatic, but it does increase risk of other sexually transmitted illnesses. Symptoms generally involve genital inflammation, itching, or discharge, though in pregnant women it can lead to preterm birth or low birth weight. 

Testing requires a urine sample, and treatment (with metronidazole or tinidazole) is generally a single dose. It’s avoidable by mutually monogamous relationships in which both partners have been STD-tested beforehand, or by using barrier methods, of course. But the medications aren’t particularly harsh, and are generally well tolerated.

The Upshot

The good news is, avoidance of most of the Neglected Parasitic Infections is pretty straightforward, and similar to avoidance of other parasitic infections:

  • Wear gloves when cleaning the cat litter box (or when otherwise possibly exposed to animal feces, such as when gardening outside).
  • Wash your fruits and veggies thoroughly before eating them.
  • Avoid raw or undercooked meat
  • Clean kitchen utensils and cutting boards well after handling raw meat
  • Keep your screens (or doors) closed and tightly sealed at night, while traveling and otherwise.