A disease that can cause neurological illness and meningitis in people, rat lungworm, has been found in wild opposums, rats and a zoo animal in San Diego County, indicating its establishment in California for the first time.

Researchers reported their findings in the journal Emerging Infectious Diseases, published by the U.S. Centers for Disease Control and Prevention. The authors, who include veterinarians, researchers and wildlife biologists, urged physicians and other healthcare workers in the region to consider lungworm infection when patients come in with nervous system disorders.

The discovery highlights “a notable expansion of the range of this parasite in North America,” they said.

The CDC website says the risk to the general public of getting this infection is low, but it can be deadly.

If ingested, the worms can cause severe headaches, stiff neck, the sensation of tingling or painful skin, low-grade fever, nausea, vomiting, coma and sometimes death. People who eat freshwater crab, prawns, frogs, snails and slugs are at greatest risk. However, people can also get the disease by eating un-rinsed produce that’s been slimed by a snail or slug, or eating a slug or snail that was chopped up in produce. The worms need moisture, however; if the produce is dry, the worms will die.

Domestic animals, including dogs and cats, are also at risk.

Officials with the California Department of Public Health were not ready to call the disease endemic, or established, in the state.

“Additional surveillance and testing will be necessary to determine whether the detections of rat lungworm in the animals evaluated in San Diego County represent an isolated introduction of the parasite or ongoing local transmission,” spokeswoman Elizabeth Manzo wrote in a statement to The Times.

The department said it is not aware of rat lungworm outside San Diego County, and has seen no human cases.

“However, the San Diego study affirms that the parasite can be introduced to California through movement of infected animals from endemic areas,” the statement said. “Because some species of snails and slugs present in California are capable of serving as hosts for rat lungworm, and the presence of the parasite in other parts of the state is unknown, it is advised to take certain food safety precautions. Persons should not consume any raw or undercooked wild snails or slugs, and should thoroughly wash all produce before consuming.”

The worms that cause the disease, Angiostrongylus cantonensis, are native to Southeast Asia. They’ve been found in the U.S. since the 1960s — including in isolated human and zoo animal cases in California — and are established in Hawaii as well as in much of the southeastern U.S.

It is believed they came overseas via rats on boats.

The worms favored environment is the moist, warm bed of a rat’s lung. When a rat is infected, the worms cause respiratory distress, priming the rodent to cough. Worm-filled sputum is then ejected into the rat’s mouth, and swallowed. The rat then poops the worms out, and animals such as slugs and snails eat the poop. When a rat eats an infected invertebrate, the cycle begins again.

Occasionally, another animal, such as a raccoon or dog, or a person, will accidentally eat an infected animal, or the slime of one, and contract the disease.

The discovery of the worm in San Diego County rodents and opossums was made by staff at the San Diego Zoo and a local wildlife rehabilitation center, Project Wildlife, which is run by the San Diego Humane Society.

In December 2024, a 7-year-old male parma wallaby, born and raised at the zoo, began showing concerning neurological behaviors: incessant head shaking, blindness, a lack of muscle coordination and paralysis in his hind legs. He was euthanized after 11 days in the zoo infirmary.

When zoo staff examined the body, they found six rat lungworms in the marsupial’s brain, along with a lot of damage.

Because the diagnosis was so unusual, zoo staff examined the bodies of 64 free-ranging roof rats that had either been euthanized in the course of regular pest control or found dead on the property. Two, a little more than 3%, had lungworms. Their feces had them too: “numerous live … larvae with coiled posterior ends.” The larvae, roughly 300 in each poop sample, were each about the size of a grain of sand.

Officials at the San Diego Zoo did not respond to requests for comment.

Curiously, at the same time the zoo investigation was underway, staff from Project Wildlife had been dealing with sick opossums brought to them from around the county. Tests of 10 dead animals showed seven carried the lungworms.

Many people and animals remain asymptomatic when they’re infected. Symptoms typically appear within hours or days after ingestion and can last up to eight weeks. The worms will eventually die.

Because the disease has so many varied symptoms, health officials say it can go undiagnosed and untreated. Health officials from Hawaii, where the disease is endemic, say if lungworms are suspected, it’s best to be treated as soon as possible — even before lab results come back.

The CDC too notes that treatment works best when the disease is caught early, and can consist of high doses of corticosteroids, lumbar punctures for symptomatic relief of headaches, and antiparasitic medications, such as albendazole.

For months, former residents of the Pacific Palisades Bowl Mobile Estates have feared the uncommunicative owners of the property would seek to displace them in favor of a more lucrative development deal after the Palisades fire destroyed the rent-controlled, roughly 170-unit mobile home park.

A confidential memorandum listing the Bowl for sale indicates the owners intend to do exactly that.

The memorandum, quietly posted on a website associated with the global commercial real estate company CBRE, says that the Palisades fire created a “blank canvas for redevelopment” at a site “ideally positioned for a transformative residential or mixed-use project.”

“I just thought, oh my god, this is so much propaganda and false advertising,” said Lisa Ross, a 33-year resident of the Bowl and a Realtor. “How can they even get away with printing this?”

Neither the current owners of the Bowl nor the real estate companies listed on the memorandum responded to requests for comment.

The memorandum describes the current single-family residential zoning as “favorable” for developers; however, the city and mobile housing law experts have painted a different picture.

“Multifamily and mixed-use development on this site is not allowed by existing zoning and land use regulations,” Mayor Karen Bass’s office said in a statement Wednesday, adding only low density single-family housing or reconstructing the mobile home park are currently allowed. “Mayor Bass will continue taking action and [work] with residents to restore the Palisades community.”

City Councilmember Traci Park also reiterated her focus on getting the mobile home park rebuilt and allowing residents to return, with a spokesperson noting she is not entertaining the potential for any rezoning efforts from a developer.

Zoning changes typically require a city council vote and are subject to the mayor’s approval or veto.

Beyond the zoning laws, the site is also currently governed by a state law requiring cities to preserve affordable housing along the coast and a city ordinance protecting mobile home residents against sudden displacement.

Spencer Pratt, a resident of the Palisades and an outspoken supporter of the neighborhood’s mobile home community, criticized the mayor and the owners in a statement to The Times. “It’s unfortunate that Karen Bass has not advocated for mobile home residents impacted by the fire,” he said, “and that the current owner of the Bowl is ignoring good faith offers from residents to buy the property.”

The mayor’s office disputed this, noting Bass recently led a delegation of Palisadians, including mobile home owners, to Sacramento to advocate for recovery. “Mayor Bass’ priority is getting every Palisadian home — single-family homeowners, town home owners, renters, mobile home owners.”

Los Angeles Mayor Karen Bass speaks during a private ceremony outside City Hall with faith leaders, LAPD officers and city officials to commemorate the one-year anniversary of the Eaton and Palisades fires on Jan. 7, 2026.

(Allen J. Schaben / Los Angeles Times)

Bass also advocated for the federal government to include the Bowl in its debris cleanup efforts; however, the Federal Emergency Management Agency ultimately refused to include it, unlike other mobile home parks impacted by the Palisades fire. Its reasoning: It could not trust the owners to rebuild the park as affordable housing.

Court rulings over the years found the owners routinely failed to maintain the infrastructure and worked to replace the park with an “upscale resort community.” Residents also accused the owners of attempting to circumvent rent control regulations.

After the fire, it ultimately took more than 13 months to begin cleaning up the debris.

Ross said she approached the owners with independent mobile home park developers who were interested in buying the fire-destroyed lot and letting residents rebuild within months. She also approached the owners with a proposition that the former residents band together to buy the park. She heard nothing back.

“They don’t communicate,” Ross said. “It’s a feuding family. That’s also why we had so many problems with maintenance and with upgrades in the park.”

Pratt, who is running for mayor against Bass, also called on private developers like Rick Caruso to step in and save the Bowl. (Caruso’s team noted his rebuilding nonprofit is looking into how to help residents of the Bowl.)

Ross is a fan of Pratt’s proposition. “We need those kinds of people — we need Rick Caruso. That would be great,” Ross said. To sweeten the deal: “I’ll cook for him. I would make him all his favorite dishes.”

A respiratory virus that doesn’t have a vaccine or a specific treatment regimen is spreading in some parts of California — but there’s no need to sound the alarm just yet, public health officials say.

A majority of Northern California communities have seen high concentrations of human metapneumovirus, or HMPV, detected in their wastewater, according to data from the WastewaterScan Dashboard, a public database that monitors sewage to track the presence of infectious diseases.

A Los Angeles Times data analysis found the communities of Merced in the San Joaquin Valley, and Novato and Sunnyvale in the San Francisco Bay Area have seen increases in HMPV levels in their wastewater between mid-December and the end of February.

HMPV has also been detected in L.A. County, though at levels considered low to moderate at this point, data show.

While HMPV may not necessarily ring a bell, it isn’t a new virus. Its typical pattern of seasonal spread was upended by the COVID-19 pandemic, and its resurgence could signal a return to a more typical pre-coronavirus respiratory disease landscape.

Here’s what you need to know.

What is HMPV?

HMPV was first detected in 2001, according to the U.S. Centers for Disease Control and Prevention. It’s transmitted by close contact with someone who is infected or by touching a contaminated surface, said Dr. Neha Nanda, chief of infectious diseases and hospital epidemiologist for Keck Medicine of USC.

Like other respiratory illnesses, such as influenza, HMPV spreads and is more durable in colder temperatures, infectious-disease experts say.

Human metapneumovirus cases commonly start showing up in January before peaking in March or April and then tailing off in June, said Dr. Jessica August, chief of infectious diseases at Kaiser Permanente Santa Rosa.

However, as was the case with many respiratory viruses, COVID disrupted that seasonal trend.

Why are we talking about HMPV now?

Before the pandemic hit in 2020, Americans were regularly exposed to seasonal viruses like HMPV and developed a degree of natural immunity, August said.

That protection waned during the pandemic, as people stayed home or kept their distance from others. So when people resumed normal activities, they were more vulnerable to the virus. Unlike other viruses, there isn’t a vaccine for human metapneumovirus.

“That’s why after the pandemic we saw record-breaking childhood viral illnesses because we lacked the usual immunity that we had, just from lack of exposure,” August said. “All of that also led to longer viral seasons, more severe illness. But all of these things have settled down in many respects.”

In 2024, the national test positivity for HMPV peaked at 11.7% at the end of March, according to the National Respiratory and Enteric Virus Surveillance System. The following year’s peak was 7.15% in late April.

So far this year, the highest test positivity rate documented was 6.1%, reported on Feb. 21 — the most recent date for which complete data are available.

While the seasonal spread of viruses like HMPV is nothing new, people became more aware of infectious diseases and how to prevent them during the pandemic, and they’ve remained part of the public consciousness in the years since, August and Nanda said.

What are the symptoms of HMPV?

Most people won’t go to the doctor if they have HMPV because it typically causes mild, cold-like symptoms that include cough, fever, nasal congestion and sore throat.

HMPV infection can progress to:

• An asthma attack and reactive airway disease (wheezing and difficulty breathing)
• Middle ear infections behind the ear drum
• Croup, also known as “barking” cough — an infection of the vocal cords, windpipe and sometimes the larger airways in the lungs
• Bronchitis
• Fever

Anyone can contract human metapneumovirus, but those who are immunocompromised or have other underlying medical conditions are at particular risk of developing severe disease — including pneumonia. Young children and older adults are also considered higher-risk groups, Nanda said.

What is the treatment for HMPV?

There is no specified treatment protocol or antiviral medication for HMPV. However, it’s common for an infection to clear up on its own and treatment is mostly geared toward soothing symptoms, according to the American Lung Assn.

A doctor will likely send you home and tell you to rest and drink plenty of fluids, Nanda said.

If symptoms worsen, experts say you should contact your healthcare provider.

How to avoid contracting HMPV

Infectious-disease experts said the best way to avoid contracting HMPV is similar to preventing other respiratory illnesses.

The American Lung Assn.’s recommendations include:

• Wash your hands often with soap and water. If that’s not available, clean your hands with an alcohol-based hand sanitizer.
• Clean frequently touched surfaces.
• Crack open a window to improve air flow in crowded spaces.
• Avoid being around sick people if you can.
• Avoid touching your eyes, nose and mouth.

Assistant data and graphics editor Vanessa Martínez contributed to this report.