Danger in Paradise: The Rat Lungworm Threat in Tropical Getaways

On December 31, 2019, Chaunda Rodrigues, 31, of Hilo, Hawaii, purchased an avocado and lettuce sandwich at a local market. But when Rodrigues started eating, something stuck to his teeth. Horrifyingly, it was part of a 2.5-inch slimy slug. Then came the retort. A few days later, a University of Hawaii lab confirmed that the creature Rodrigues bit contained Angiostrongylus cantonensisa foodborne parasite that can invade the human brain.

Since then A. cantonensis, also called “rat lungworm”, was first discovered in southern China in the mid-1930s, the neurotropic nematode has slowly but inexorably spread. Today it inhabits tropical islands and hot and humid areas of the five continents. Although rats are the parasite’s definitive host, humans most often become ill after ingesting infective larvae inside snails and slugs, many of which are invasive species. A classic example is the Asian semi-slug. parmarion martensi. Since it was first identified on Oahu in 1996, on the Big Island in 2004, and on Maui in 2017, P. martensi has often entered human habitats with large loads of larvae. Once inside humans, those same larvae make their way to the central nervous system where they normally grow and die, sometimes leaving deadly inflammation and neurological damage in their wake.

Rodrigues was not a passive person. Once his dilemma became clear, he quickly obtained an anthelmintic drug called albendazole (Albenza). He also posted on Facebook, publicly sharing the saga of him and a vivid photo of the sticky gastropod cut from him. Finally, 2 weeks after biting the slug, Rodrigues and her husband filed a lawsuit against Island Naturals Market for negligence in failing to clean the ingredients of the sandwich she made and sold to avoid exposure to a potentially fatal parasite.

What is the risk? hard to say

Although many diseases due to A. cantonensis undiagnosed or never reported, in 2019, there were nine official cases among local residents and visitors to the Big Island of Hawaii. Did some albendazole pills protect Rodrigues from the same fate? No one knows for sure, but luckily it held up well. The bad news, on the other hand, is that millions of people visit Hawaii each year knowing nothing about rat lungworm, including answers to such basic questions as: What the heck is it? How can I avoid it? How is it diagnosed? Are there early warning signs that allow me to receive quick and effective treatment before complications develop? The same ignorance holds true for most of your home doctors.

One patient who learned this the hard way is a 56-year-old woman from Seattle who, like many others right now, couldn’t wait to enjoy sweltering sun and balmy trade winds after life under lockdowns and more restrictive protocols. of COVID. Unaware that a dangerous parasite could contaminate local produce, Julie Packard happily ate several salads and a vegetable wrap during her 8-day stay on the island of Hawaii in December 2021. Her first symptoms (a strange chest tightness and sporadic tingling) began before she left. Days later, Packard also suffered from myalgia, burning pain, and a rash on his trunk followed by impaired vision and balance. Bottom line? It wasn’t until after 5 weeks of worsening symptoms that Packard finally underwent a lumbar puncture and a small sample of her cerebrospinal fluid was sent to the NIH Parasitic Diseases Laboratory. There, an ultrasensitive test for A. cantonensis The DNA came back strongly positive, but his brain was already damaged. Even 3 months later, despite 2 weeks of albendazole and continued Decadron treatment, the once-athletic social worker still had double vision and an unsteady gait.

Other telltale signs and dire consequences of neuroangiostrongyliasis include severe and incessant headaches, paresthesias, bowel and bladder dysfunction due to radiculomyelitis, hydrocephalus and coma, and even death.

The biological backstory and transmission through food

As any medical student can attest, you can’t talk about “parasite” without mentioning “life cycle”. The terrestrial cycle of the rat lungworm first became apparent in the 1950s and 1960s. In short: adult A. cantonensis the worms live and mate in the pulmonary arteries of rats, the fertilized eggs hatch in the rats’ lungs, and the young larvae pass through the rats’ feces. After the snails and slugs eat that feces and their larvae mature, the cycle starts all over again when a new gang of rats eat the mollusks.

How do people get into the picture? In the first decades after the discovery of rat lungworm, most human cases (often presenting as eosinophilic meningitis) were related to the consumption of raw or undercooked freshwater snails or shrimp. However, in the 1960s, research in Hawaii and Polynesia suggested that fresh green leafy vegetables harboring snails or flatworms could also carry infections. A famous outbreak in 2000, in which 12 Chicago medical students developed rat lungworm meningitis after sharing a large Caesar salad in Jamaica, left no further doubt that produce could also transmit the nerve-invasive nematode.

A globalizing parasite that needs more attention

Many lessons can be drawn from the modern rat lungworm saga, from its ongoing global spread (today, the parasite thrives happily in Southeast Asia, the Pacific Islands, Japan, Australia, South America, the Caribbean and also the southeastern US as parts of Africa and the Canary and Balearic Islands) to the need to weigh healthy eating against a genuine danger of foodborne transmission in these and other endemic sites. Fortunately, thorough washing of products eliminates infections A. cantonensis-Infected molluscs, cooking and freezing directly kill the larvae, and early treatment mitigates the disease. At the same time, if residents and tourists in the affected areas are not warned, how can they practice self-protection measures?

While many challenges remain in controlling A. cantonensis, one thing is clear. As you continue to move and establish new homes, widespread education of those at risk Y your doctors will be key to reducing damage and, even better, preventing infections in the first place.

Claire Panosian Dunavan, MD, is a professor of infectious diseases at the David Geffen School of Medicine at UCLA and past president of the American Society of Tropical Medicine and Hygiene. She recently produced a documentary on rat lungworm disease, called “Accidental Guest: The Story of Rat Lungworm Disease,” which will air in the fall.

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