Rat lungworm disease is popping up in the mainland United States

Health officials have confirmed 12 cases of rat lungworm disease in the continental United States since January 2011 — including six patients who had not traveled abroad but still contracted the illness caused by a parasite endemic to tropical regions in Asia and Hawaii.

While the disease can be mild, it can become extreme and cause severe neurological problems. In most of the new cases, patients complained of headache, fever, weakness and symptoms consistent with meningitis, the U.S. Centers for Disease Control and Prevention reports in the Aug. 3 Morbidity and Mortality Weekly Report.

The disease is also known as angiostrongyliasis, after the parasitic roundworm Angiostrongylus cantonensis whose larvae hatch in the lungs of rats and then are expelled in the rodents’ excrement. At that point, the larvae can be picked up by snails and slugs, and then passed along to humans if the snails and slugs are eaten raw. On July 30, researchers added centipedes to the list of creatures that can transmit the disease to humans, after a Chinese woman and her son contracted the disease in 2012 after eating raw centipedes bought at a market (SN Online: 7/30/18).

More than half of the recent U.S. cases involved patients who had eaten raw vegetables, likely inadvertently consuming a snail or slug, and at least one case involved a toddler who ate slugs while playing. Of the six cases confirmed as originating within the country, four were reported from Texas, one from Tennessee and one from Alabama.

“We don’t know exactly the source of the infection,” CDC epidemiologist Susan Montgomery says. “Fresh produce really should be washed thoroughly and carefully.”

The CDC also confirmed 18 cases and reported three more probable cases in 2017 alone in Hawaii.

Montgomery and her team only tracked cases sent to CDC labs for testing, meaning there may be more undiagnosed cases.