Steroid, spinal tap among new rat lungworm guidelines

  • Photo courtesy University of Hawaii at Manoa Snails, rats and slugs can transmit the rat lungworm parasite.

A joint task force created by Gov. David Ige to combat rat lungworm disease announced on Thursday new preliminary guidelines to help physicians diagnose, treat and manage the illness.

The task force’s clinical subcommittee spent the last year crafting the guidelines, which will be presented during the annual meeting of the American Society of Tropical Medicine and Hygiene in November, according to the state Department of Health.


Subcommittee chairman Vernon Ansdell, a physician with more than 45 years of experience in internal and tropical medicine, said that prior to the group’s work, there were no clear or reliable diagnosis or treatment protocols available for Hawaii physicians.

Diagnosis can be problematic because infected patients don’t always present the same symptoms, said Ansdell, who is also an associate professor at the University of Hawaii John A. Burns School of Medicine.

“These preliminary guidelines provide critical guidance to physicians to help them make timely and accurate diagnoses and give their patients the best possible treatment available,” he said.

Rat lungworm disease, also known as angiostrongyliasis, is caused by a parasitic roundworm and can affect a person’s brain and spinal cord.

According to the DOH website, the adult parasite is found only in rodents, but its larvae can be passed through feces. In turn, creatures like snails and slugs can become infected by ingesting the larvae. Humans get rat lungworm by accidentally eating infected snails or slugs.

In a phone interview, Ansdell said that while prevention is “really important” and there are prevention guidelines available, “unfortunately, that doesn’t always work, and we need to be alert to the possibility that people are still going to develop this infection.”

The earlier a diagnosis is made, the earlier treatment can start, he said.

But in the first stages of the disease, Ansdell said symptoms are “very nonspecific” and it requires informed medical providers who will pick up on the “complicated medical situation” early.

Ansdell said the main concern about the infection is inflammation caused by the dead parasite. Therefore, for treatment, “the most important drug is a steroid that suppresses inflammation.”

The preliminary guidelines also call for a complete neurologic examination, a carefully sought exposure history, and emphasize the importance of a lumbar puncture, or spinal tap, in diagnosing the disease.

It “sounds very dramatic, a spinal tap,” Ansdell said, but it’s a “standard procedure” and is “invaluable when it comes to making the diagnosis.”

It also helps with treatment by relieving pressure in the brain, he said.

Anna Koethe, public health information coordinator for the DOH, said the development of the new guidelines is a “crucial and imperative step forward.”

“With these guidelines, the joint task force has given Hawaii physicians a clear, evidence-based tool they can use to identify the disease in a manner that is both timely and accurate, take the proper steps to diagnose them, and provide the best possible treatment and management of the disease,” she said.

According to Koethe, Hawaii reported its first case of rat lungworm disease in 1961.

In 2017, there were 18 confirmed cases and three probable cases in the state.

Five cases have been confirmed statewide by the DOH in 2018, including three on the Big Island.

The latest came earlier this month when the DOH confirmed the diagnosis in an East Hawaii toddler.

According to the DOH, the task force was established in May 2016, and is comprised of members from the medical, scientific, environmental and public health communities.


The preliminary guidelines can be found online at

Email Stephanie Salmons at

Leave a Reply

Your email address will not be published. Required fields are marked *


By participating in online discussions you acknowledge that you have agreed to the Star-Advertiser's TERMS OF SERVICE. An insightful discussion of ideas and viewpoints is encouraged, but comments must be civil and in good taste, with no personal attacks. If your comments are inappropriate, you may be banned from posting. To report comments that you believe do not follow our guidelines, email