Hawaii Health Alert: Protecting Yourself From Rat Lungworm Disease

Hawaii Health Alert: Protecting Yourself From Rat Lungworm Disease

This parasitic infection can have major consequences for your health.

Rats have long been the vector for human disease—from the bubonic plague to leptospirosis—and in Hawaii today, they’re responsible for yet another infection: rat lungworm disease. Angiostrongyliasis, or rat lungworm disease, made national headlines in 2017 when an outbreak caused 18 confirmed, and 3 suspected cases of the disease in Hawaii. As of April 2019, there were three confirmed cases so far, with more likely by the end of the year. But what is rat lungworm disease and how can you stay safe?

Parasites spread by rat poop
Rat lungworm disease is a type of parasitic nematode (roundworm) commonly found in rats or slugs and snails. The adult form of the parasite is found in rats where the roundworm can reproduce. Infected rats pass parasite larvae in their stool, where snails and slugs pick them up and pass them along. Most individuals get rat lungworm from direct contact with snails or slugs, including eating them, or from unwashed produce where the mollusks were present.

Protect yourself against parasites
The disease may result in eosinophilic meningitis, a parasitic form of meningitis that can cause severe headache, stiffness in the neck, fever, vomiting, light sensitivity, and a tingling or painful sensation in skin. Some people who contract angiostrongyliasis will never show symptoms. Generally, only those who develop eosinophilic meningitis will show major symptoms, which typically occur about one to three weeks after exposure.

Testing for rat lungworm is difficult as there are no specific blood tests available. In Hawaii, the Department of Health can confirm a diagnosis by running a polymerase chain reaction test to look for parasitic DNA in the patient’s cerebrospinal fluid (CSF). More commonly, healthcare providers will look at a patient’s history to see if they’ve had possible exposure and if their symptoms match eosinophilic meningitis. From there, they can look for eosinophils (a type of blood cell) in the patient’s CSF to provide a diagnosis.

Prevention is key
According to Sarah Park, MD, head of the Disease Outbreak Control Division for the State of Hawaii, there are some simple ways that residents can reduce their risk of exposure:

  • Wash your lettuce leaf by leaf
  • Keep small keiki from touching slugs and snails or putting them in their mouths
  • Don’t drink from garden hoses where slugs may reside
  • Never eat raw or undercooked snails, slugs, shrimp, crabs, or frogs

There is no specific treatment for rat lungworm disease. The parasite cannot grow or reproduce in humans and will eventually die. Despite alarmist news headlines whenever a new case is confirmed, rat lungworm infection is very rare. During the 2017 outbreak, there were only 21 confirmed and probable cases for Hawaii’s 1.4 million residents.

If you suspect you may have eaten an uncooked snail or slug or have otherwise been exposed to rat lungworm disease, see your healthcare provider right away.

Medically reviewed in March 2020.

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