Creepy Crawlies: Pinworms, Tapeworms, Parasites and More

With the school year in full swing and winter creeping in, communicable diseases are running amuck.  Coughs, colds and GI bugs are everywhere.  I don't mind reassuring moms that yes, this case of influenza will pass, but my favorite diagnoses to treat are those that make people go "Ick".  Worms and parasites are among my favorite cases with a high ick factor.  Even ickier, half of the world's population is infected with at least one worm.  Are you itching yet...

Fortunately, for us in the U.S., parasitic infections are most common in tropical regions and developing countries  But, there are still plenty of cases of worms and parasites to go around right here at home and as a nurse practitioner or physician assistant you will likely treat them in your clinic or hospital on occasion.  Here's a quick review of the different types of worms and parasites you may encounter in your practice.


If you've been an NP or PA for any amount of time, you've probably treated pinworms.  Pinworms are thin, white, worms anywhere from 2 to 13mm long.  They are found primarily in children and are transmitted through direct contact.  Usually, the only symptom of pinworm infestation is rectal itching.  Pinworms can often be seen with the naked eye.  Placing a piece of tape on the rectum then removing it and examining it under a microscope can also detect the presence of pinworms and their eggs.  Pinworms should be treated with an antihelminthic medication such as mebendazole.  At least 3 doses of the medication given 3 weeks apart are necessary for successful eradication.  Close contacts such as family members should also be treated.


Though not as prevalent in the United States, roundworms affect one fourth of the world's population.  Individuals become infected after ingesting eggs in feces-contaminated soil or food.  The ingested eggs then hatch in the small intestine releasing small larvae that burrow through the intestinal wall and eventually into pulmonary vasculature.  Larvae mature in the respiratory tract, then travel back to the intestines to lay eggs.  When present in the respiratory tract, roundworms can cause pulmonary symptoms like cough and wheezing.  GI symptoms occur later in infection and may include passing worms (yuck), abdominal pain, nausea and vomiting.  Roundworms may be diagnosed by a stool sample during the later course of infection (after 40 days) when the worms are present in the intestine.  Roundworm infection is treated with antiparasitic drugs. 


Most of us are all too familiar with scabies.  Scabies is caused by tiny mites, invisible to the naked eye.  Mites burrow into the skin causing intense pruritis and rash consisting of papules in a linear pattern.  The most commonly infested areas are the webs of the fingers and toes as well as the genital area.  Scabies is most often transmitted by skin to skin contact but can be transmitted from objects.  Diagnosis is clinical but can be confirmed with a skin scraping.  Topical permethrin is the most effective treatment for scabies.  Antihistamines may also be given to help relieve itching. 


An astounding 576-740 million individuals are infected with hookworm.  Though less prevalent in the United States, hookworm infections are not uncommon in the southeastern U.S.  Hookworms are transmitted in soil and live in the small intestine. The infection is usually acquired when walking barefoot on contaminated soil.  Many people have no symptoms with hookworm infection.  Others experience itchiness or rash on the feet at the site where hookworms enter the skin, others have diarrhea as hookworms grow in the intestine.  The most severe symptom of hookworms is anemia which in rare cases may lead to heart failure.  Antiparasitic medications are effective for eradicating hookworm infection. 


A sexually transmitted infection, trichomoniasis is cause by a protozoa.  It is one of the most common STI's worldwide.  Infected individuals are often asymptomatic but may experience discharge or urethritis.  Diagnosis is based on microscopy in which motile trichomonads are observed.  Oral metronidazole is the treatment of choice. 


Tapeworms are flat, segmented worms residing in the intestines.  The worms are a result of eating undercooked meat from an infected animal.  Tapeworms cause few symptoms and are usually treated without complication.  Possible symptoms include nausea, diarrhea, weakness, hunger, fatigue and weight loss.  Often, the only symptom of tapeworm infestation is segments of worms, possibly moving, in bowel movements.  Rarely, tapeworms can migrate to other parts of the body like the eye, liver, heart or brain which can be life threatening.   Tapeworm infection is diagnosed by stool sample analysis or by testing the blood for certain antibodies.  Most tapeworm infections are easily treated with oral praziquantel.


We are all familiar with pediculosis, or head lice.  The primary symptom of head lice is itching as well as visualization of the insects or nits (eggs).  Contrary to popular belief, lice are transmitted by person-to-person contact and do not hop, jump or fly.  The most effective treatment for head lice is topical permethrin.  A second treatment is recommended within 7 to 10 days to kill newly hatched insects. 


Toxoplasmosis is a parasitic protozoa.  Infection is caused by consuming undercooked meat as well as by fecal contamination.  Most individuals with toxoplasmosis are asymptomatic.  Immunocompromised individuals, however can have severe symptoms as the infection may go to the central nervous system causing seizure, altered mental status, headache and neurological deficits.  The infection can also affect the eyes causing ocular pain, blurred vision, red eye, impaired vision and floaters.  Diagnosis is made either by identifying the protozoa in blood directly or by testing for specific antibodies.  Treatment is usually unnecessary in asymptomatic individuals except in children under 5 years of age.  In immunocompromised and symptomatic individuals oral and/or IV medications as well as supportive therapy are used for treatment. 


Giardisis, commonly known as Giardia, is a parasitic illness caused by the protozoa Giardia lambia.  Giardia infects the small intestine and is a common cause of gastroenteritis causing symptoms like diarrhea, hematuria, stomach cramps, vomiting, bloating and burping.  Most infected individuals are asymptomatic with only one-third of infected individuals showing signs of illness.  Transferred via the fecal-oral route, Giardia is caused by consumption of contaminated food or drinks.  It is most commonly seen in individuals who go hiking or camping or those who live in wilderness areas.  Giardia can be diagnosed by stool sample or by testing the blood for antibodies.  The diagnosis can be easily missed so multiple tests should be done over a one-week period for accurate diagnosis.  The infection typically resolves on spontaneously.  In individuals where the infection persists, it may be treated with metronidazole. 

Trichuris (Whipworm)

Trichiuris, also known as whipworm, is a common intestinal infection affecting more than a quarter of the world's population.  It is most common in developing countries.  Whipworm is spread by fecal-oral transmission and infects the intestines with worms feeding on intestinal secretions.  Most individuals are asymptomatic.  Those who do exhibit symptoms may have loose stools, failure to thrive, anemia, abdominal discomfort or rectal prolapse.  Whipworm is diagnosed by the presence of eggs on stool smear and is treated with oral mebendazole. 


Cryptosporidiosis is a parasitic infection spread through water, either drinking water or recreational water.  It is found in every area of the world and is transmitted by the fecal-oral route.  Symptoms of cryptosporidiosis include wattery diarrhea, abdominal cramps, nausea, vomiting, fever and weight loss.  Supportive therapy including rehydration and electrolyte monitoring is important in cryptosporidiosis infection.  Nitazoxanide is the medication of choice.   

If reading about these worms, parasites and protozoa doesn't remind you of microbiology 101, I don't know what will!  As nurse practitioners and physician assistants we will see some of these infections often.  Others, we may never treat. It's important we be aware of the potential for these types of parasitic infections as they can have serious implications in some patients.

Have you treated any interesting parasitic infections in your practice?