Boy's Brain Started to Rot After Rare Parasitic Infection

A 17-year-old boy in China contracted a rare parasitic infection and the disease destroyed parts of his brain, a case report shows.

The patient visited an emergency department at Qinghai University Affiliated Hospital in the central China city of Xining after he experienced dizziness, headaches and weakness in his right leg for three weeks, according to an article in The New England Journal of Medicine (NEJM).

Medical staff conducted scans of his head, which revealed lesions in two parts of his brain. The lesions were later shown to display signs of necrosis, a term used to refer to the death of body tissue.

Doctors removed the lesions, and subsequent tests led them to diagnose the patient with a form of alveolar echinococcosis (AE)—a rare, neglected and life-threatening disease caused by infection from the parasitic tapeworm species Echinococcus multilocularis.

This disease occurs around the world but is primarily found in the Northern Hemisphere in such places as China, Russia, Central Europe, Central Asia, Japan and North America. In the latter, it is mostly seen in the region stretching from eastern Montana to central Ohio, as well as in Alaska and Canada, according to the U.S. Centers for Disease Control and Prevention.

AE is caused by the larval stage of the E. multilocularis tapeworm, which grows to roughly 1 to 4 millimeters in length as an adult and is found in animals such as foxes, coyotes and dogs—the primary hosts. Other animals, like some small rodents, can act as intermediate hosts for the tapeworm.

The disease primarily affects the liver, causing tumor-like lesions. But the parasite larva can also spread to other body parts like the lungs and, in very rare cases, the brain, as seen in the 17-year-old Chinese patient.

When the infection affects the brain, it is described as "cerebral alveolar echinococcosis." In these cases, the parasite larva gradually damages the surrounding healthy brain tissue.

"Almost all patients with cerebral echinococcosis come to the hospital with headaches and/or dizziness," Hu Ju, a doctor at Qinghai University Affiliated Hospital who treated the boy, told Newsweek.

The lesions caused by the disease are very similar to brain tumors and can mimic the symptoms. In fact, they are often diagnosed as tumors.

"When the microorganism reaches the brain by blood circulation it produces a mass lesion," Mete Zeynal, a professor at Atatürk University's School of Medicine, in Turkey, told Newsweek.

"This mass lesion in the brain acts like a real brain tumor—it causes seizures, headaches, nausea, vomiting. As with every growing mass in the brain, when it starts growing, it increases the intracranial pressure, and this is the main cause of the symptoms," Zeynal said.

In the case of the 17-year-old boy, examination of the lesions after surgery revealed evidence of necrosis in the center.

Following the operation, Hu and colleagues prescribed for the boy a long course of albendazole, a drug used for the treatment of various intestinal parasite infections. After two months of follow-up, the patient's clinical symptoms had resolved. But doctors said there was still a chance the disease could recur in the future.

While albendazole decreases the viability of the parasite, it does not kill it, and the disease can return once the patient stops taking the medication. Even with long-term use of the drug, the disease can still recur. No drugs have been developed to date that can kill Echinococcus directly.

If left untreated, the disease can be fatal. A study authored by Zeynal describes alveolar echinococcosis as "one of the most dangerous zoonotic diseases" in the Northern Hemisphere. Zoonotic diseases are infections that are spread between people and animals.

"The survival rate of patients with echinococcosis is low and effective drugs are not available," Hu said. "My area is endemic for alveolar echinococcosis. We treat about 30 cases of cerebral alveolar echinococcosis every year. Only a third of these patients have access to surgical treatment."

The most common way humans become infected with a tapeworm is through close contact with infected animals. The patient in the NEJM article had not reported this, but people can also become infected in other ways, such as eating food contaminated with the eggs of the tapeworm, which are released in the feces of host animals like foxes and dogs.

People at higher risk of contracting the disease in endemic areas are those who live in rural settings, near forests or in mountain climates, as well as farmers or dog owners, a study published in the journal Open Forum Infectious Diseases shows.