August 04, 2018
2 min read

Rat lungworm infection linked to raw vegetables in continental US

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Photo of Eugene Liu
Eugene W. Liu

Twelve cases of human infection with Angiostrongylus cantonensis, otherwise known as rat lungworm, have been identified in the continental United States, with possible sources including raw vegetables from local gardens, according to study results from the CDC.

“Ingestion of snails or slugs containing rat lungworm (A. cantonensis) larvae can result in angiostrongyliasis, an illness that can cause inflammation of the lining of the brain,” Eugene W. Liu, MD, CDC epidemic intelligence service officer, told Infectious Disease News. “Angiostrongyliasis typically occurs in Asia and the Pacific Islands, including Hawaii. However, the CDC recently identified 12 angiostrongyliasis cases in the continental United States.”

Liu and colleagues identified cases of human angiostrongyliasis by reviewing A. cantonensis PCR testing on cerebrospinal fluid between January 2011 and January 2017. They detected A. cantonensis DNA in 34 of 69 specimens.

Sixteen patients (median age, 20 years; 10 men) from eight states in the continental U.S. (California, Texas, Utah, Colorado, Arizona, Alabama, Tennessee and New York) were considered presumptive angiostrongyliasis cases, with eight of those patients having traveled outside the continental U.S. during the prior 12 months. Complete clinical information was available for 12 of the patients who had a confirmed diagnosis of angiostrongyliasis.

Angiostrongylus cantonensis third stage (L3), infective larva recovered from a slug. Image captured under differential interference contrast (DIC) microscopy.
Angiostrongylus cantonensis third stage (L3), infective larva recovered from a slug.
Source: CDC

Six patients had reportedly consumed raw vegetables from local gardens, whereas two reported consuming raw snails and two others had reported snails in their environment. Two patients had reported consumption of prawns, with one patient specifying the prawns were cooked, whereas one patient reported consuming cooked crab.

Six patients from Texas, Tennessee and Alabama had not traveled outside of the continental U.S. Two reported eating raw vegetables, three reported possible exposure to snails or slugs and one reported a history of geophagia.

The researchers noted that A. cantonensis infection is found in snail species in Florida and Louisiana and in rat species in Louisiana, Florida and Oklahoma.

The 12 patients with confirmed angiostrongyliasis reported generalized weakness, headache and had cerebrospinal fluid consistent with meningitis. Eleven of the patients were treated with systemic steroids, and seven received albendazole, an antiparasitic. All patients were alive 2 months after initial evaluation, with 11 having reported improved symptoms.

“Health care providers, especially those in the southern United States, should consider this parasitic illness in patients with inflammation of the lining of the brain with a history of ingestion of snails, slugs, or raw vegetables contaminated with larvae,” Liu said. “Consumers and food preparers should thoroughly wash produce before eating or serving it uncooked.”

Gardeners and parents should be aware of the risk, he added.

“Keep rats, snails and slugs away from your garden,” Liu said. “Prevent children from ingesting dirt, snails and slugs as possible. Thoroughly wash children’s hands after playing outside.” – by Bruce Thiel

Disclosures: Liu reports no relevant financial disclosures. Please see the study for the other authors’ relevant financial disclosures.