Remember neurocysticercosis? This difficult-to-pronounce infectious disease is found mainly among people living in Latin America, China, and India. Because this disease causes psychiatric symptoms, consultation-liaison psychiatrists working in areas populated by immigrants from these countries should be familiar with making a differential diagnosis, said C-L psychiatrist Robert Schneider, M.D., at the annual meeting of the Academy of Psychosomatic Medicine last month.

The disease is transmitted by ingesting tapeworm eggs found on food that has been contaminated with hog or human excrement or handled by people with unwashed hands who carry the tapeworm, said Schneider, an assistant professor of psychiatry and internal medicine at the Medical College of Virginia in Richmond.

The most serious symptoms occur when the tapeworm eggs grow in the brain. The tapeworm heads die, triggering an immune system response, and the surrounding tissue becomes inflamed and ultimately calcified, according to Schneider.

"This inflammation causes symptoms that include psychosis, delirium, and seizures. Later in the course of the disease, depression, cognitive decline, and hydrocephalus can occur," said Schneider.

He continued, "When looking at psychiatric aspects of infectious diseases, two important considerations are demographics and immune-system status," he said.

To illustrate how to make a differential diagnosis, he presented the hypothetical case of a 34-year-old woman from Mexico with a brief history of postpartum paranoid ideation and auditory hallucinations. "Her clinical history reveals that she and her family have a long history of seizures. "Research has shown that entire villages can experience seizures after being infected with pork tapeworm eggs," said Schneider.

Because the woman is from a country where people are at risk for several infectious diseases, it is important to rule out HIV, tuberculosis, brain abscess, and toxoplasmosis, which is caused by ingesting food-borne parasites.

In a case such as this, "I would order a head computed tomography (CT) scan, a cerebral spinal fluid (CSF) tap, a blood work-up including HIV and a complete blood count (CBC), and a urine drug screen," said Schneider.

The CT scan revealed multiple cysts and calcified lesions in her brain, similar to what is seen in toxoplasmosis. However, because her HIV test was negative, and CBC and CSF tests showed no abnormalities, toxoplasmosis, a brain abscess, and TB had to be ruled out, according to Schneider.

Another test, an immunoblot assay can be used to detect neurocysticercosis, but it is highly specific and has variable sensitivity, he pointed out.

"Although mixing a sample of the patient’s blood with antibodies developed in response to the disease is 100 percent specific, the immunoblot assay’s sensitivity depends on having multiple number of cysts and the size of the calcifications. If the test is negative, that doesn’t mean the disease is not present," said Schneider.

He believes the CT scan and clinical history are more accurate.

The drug praziquantel (biltricide) has been used to treat tapeworm diseases by preventing their further spread. However, a recent randomized clinical trial suggests that conservative treatment with antiseizure medications and corticosteroids is just as effective as praziquantel, said Schneider. He also mentioned that surgical shunting is indicated if hydrocephalus is present.

"After treating the symptoms, the next step is contacting the health department to find out how the individual got the infection and whether other family members are infected," said Schneider.