A virus without a vaccine or treatment is hitting California. What you need to know

A respiratory virus for which there is no vaccine or specific treatment regimen is spreading in parts of California; But public health officials say there’s no need to sound the alarm just yet.

High concentrations of human metapneumovirus, or HMPV, have been detected in the wastewater of the majority of Northern California communities, according to the data. Wastewater Screening Control PanelA public database that monitors sewage for the presence of infectious diseases.

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

Data shows that HMPV has also been detected in LA County at levels considered low to moderate at this point.

Although HMPV does not necessarily ring a bell, it is not a new virus. Here’s how the typical seasonal spread pattern is turned upside down: COVID-19 outbreakand its resurgence could signal a return to a more typical pre-coronavirus respiratory disease environment.

Here’s what you need to know.

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What is HMPV?

HMPV was first detected in 2001. US Centers for Disease Control and Prevention. Dr. D., chief of infectious diseases and hospital epidemiologist at USC Keck Medicine. Neha Nanda said the virus is transmitted through close contact with an infected person or touching a contaminated surface.

Infectious disease experts say HMPV, like other respiratory diseases like flu, spreads and is more resilient in cold weather.

Kaiser Permanente Santa Rosa chief of infectious diseases Dr. Jessica August said cases of human metapneumovirus usually begin to appear in January, then peak in March or April and then decline in June.

But like many respiratory viruses, COVID has disrupted this seasonal trend.

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Why are we talking about HMPV now?

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

This protection has diminished as people stayed home or kept their distance from others during the pandemic. So when people resumed their normal activities, they became more vulnerable to the virus. Unlike other viruses, there is no vaccine against human metapneumovirus.

“That’s why we saw after the pandemic record-breaking childhood viral diseases “because we didn’t have the usual immunity that we have because of the lack of exposure,” August said. “All of this has also led to longer viral seasons and more severe disease. But all of that has calmed down in many ways.”

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

The highest test positivity rate documented so far this year was reported on February 21, at 6.1%; The latest date for which complete data is available.

Seasonal spread of viruses like HMPV is nothing new, August and Nanda said, but people have become more aware of infectious diseases and how to prevent them during the pandemic, and these issues have remained part of the public consciousness in recent years.

What are the symptoms of HMPV?

Most people do not see a doctor if they have HMPV because it usually causes mild, cold-like symptoms such as cough, fever, nasal congestion, and sore throat.

HMPV infection can progress as follows:

• Asthma attack and reactive airway disease (wheezing and difficulty breathing)

• Middle ear infections behind the eardrum

• Croup, also known as “barking” cough – infection of the vocal cords, windpipe, and sometimes large airways in the lungs

Anyone can catch human metapneumovirus, but those with compromised immune systems or other underlying medical conditions are at risk of serious illness, including pneumonia. Young children and older adults are also considered high-risk groups, Nanda said.

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What is the treatment for HMPV?

There is no established treatment protocol or antiviral drug for HMPV. However, it is common for an infection to heal on its own, and treatment is mostly aimed at relieving symptoms. American Lung Assn.

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

Experts say that if symptoms worsen, 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 diseases.

The American Lung Assn.’s recommendations include:

• wash your hands often with soap and water. If this is not possible, clean your hands with alcohol-based hand sanitizer.

• Clean frequently touched surfaces.

• Open a window to improve airflow in crowded areas.

• Avoid being around sick people if possible.

• Avoid touching your eyes, nose and mouth.

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

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This story first appeared on: Los Angeles Times.