Why Aren’t Doctors Finding Parasites?

By Dr. Margaret Williamson Infectious Disease Specialist, Georgia Infectious Diseases

Posted on | By Dr. Margaret Williamson

Parasites can be subtle, and you don't need to travel to the jungle to become infected with a parasite. Simply going to the park or hiking in the woods can be enough.  Few doctors can recognize common symptoms or problems as parasitic infections.  Doctors will also need lab tests and exposure histories to find these sneaky parasites. However, not all doctors are trained to look for parasites. Infectious disease specialists are best qualified to diagnose and treat these conditions.

Here are three parasites to watch out for:


Toxocara is a dog or cat roundworm that can accidentally infect humans. Typically these worms live in the gut of your pet. The eggs of the parasite are released in poop that can infect the soil. The tiny larvae within the egg live a long time in the soil, silently waiting for the next animal to pick them up. They are regularly found in city parks, sandboxes and areas of dirt where pets poop on a regular basis. The southeastern US has the most cases.

Humans are exposed to toxocara by playing in the dirt – either in the park or in their own gardens. The eggs can get on our hands or under our nails. If we put those hands in our mouth, eat before washing our hand or get our fingers too close to our faces, we can accidentally put the eggs into our body. Children are particularly at risk since they are not the best at washing their hands.

Toxocara can cause fever, flu-like symptoms, swollen liver, wheezing, cough and shortness of breath. Sometimes it can cause seizures, behavioral changes or poor appetite. These widespread symptoms correspond to where the small larvae travels throughout the body. This condition is called visceral larva migrans. Visceral means organs, larva means worm hatchlings and migrans means traveling in many directions.

However, there are more subtle versions of toxocara that can be much more difficult to diagnose. Covert toxocaraiasis may just cause abdominal pain, poor appetite, isolated wheezing or coughing. The worm can travel into the eye on its random journey in the body. The retina can become very inflamed and the center part of the eye can get cloudy.  This is called ocular toxocara.

To diagnose a toxocara infection, your doctor should start with basic blood tests, including blood counts. When the larva travels through the body, your eosinophils increase to very high levels in your blood. This is a major clue that disseminated parasites are causing the problem. Eosinophils are a type of white blood cell that attack parasites. Specific antibody tests for toxocara can then pinpoint this worm as the cause of the infection.

To treat the infection, there are several pill antibiotics that kill toxocara. Both mebendazole and albendazole are commonly used. Treatment usually lasts 1 to 3 weeks. If there is eye involvement, doctors use steroids to calm the inflammation. The patient may need surgery to clean the center part of the eye. Sometimes people need multiple rounds of both antibiotics and steroids to treat relapses.

To prevent a toxocara infection, make sure to wash your hands after working in the yard or playing in the dirt. Treat your pets on a regular schedule for roundworms.  Pregnant dogs should also be treated so their litters do not get infected. And be sure to scoop your pet’s poop!

Article written by Dr. Margaret Williamson
Infectious Disease Specialist, Georgia Infectious Diseases