There were nine cases of rat lungworm disease acquired in Hawaii County in 2019, state health department officials announced Thursday.

An adult resident of Kauai is believed to have caught the parasitic disease during a December trip to the Big Island, making the individual the sixth Hawaii resident to fall ill. The other three cases were tourists.

Adult female nematodes recovered from rat lungs
Angiostrongylus cantonensis parasitic larvae can unknowingly find themselves in human hosts and cause severe neurological damage and even death as they mature into nematode worms. CDC, DPDx

The symptoms this patient felt included headaches, nausea, vomiting, neck stiffness and joint pain, prompting the person to seek medical care.

A medical investigation was unable to determine how the person contracted the disease.

Angiostrongylus cantonensis is a parasitic nematode that infects animal carriers such as slugs or snails via rat feces. Accidental ingestion of small slugs appear to be the most common scenario for human infection.

The late January diagnosis of a patient in December highlights the delays rat lungworm disease patients can face as they wait for answers about their ailments. The widely varying symptoms caused by the disease can make it difficult to diagnose.

Its symptoms can be mistaken for the common flu. But as the parasite develops, it can cause long-term damage and even death.

Three lawsuits within the past 12 months have been filed against Hawaii eateries alleging the plaintiffs fell ill with the disease after being served food with infected slugs in it.

“Thoroughly inspecting and rinsing all fresh fruits and vegetables under clean, running water can go a long way in making our food safer to eat, and it is the most effective way to remove pests and other contaminants,” said Dr. Sarah Park, state epidemiologist. “When in doubt, cooking food by boiling for 3 to 5 minutes or heating to an internal temperature of 165 degrees Fahrenheit for at least 15 seconds can kill the parasite that causes rat lungworm disease.”

The Hilo Medical Center recommended this month that anyone who believes they have ingested a snail or slug to take an over-the-counter pinworm medication as a possible — but not yet medically proven —  preventative measure.

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