California just broke a 28-year-old record for fatal rabies detections

Two sick raccoons discovered this month in a Los Angeles suburb have set off alarm bells from California to Georgia, where officials at the U.S. Centers for Disease Control and Prevention have taken notice. The animals, found three weeks apart in Westlake Village, are the first raccoons in the county to test positive for rabies since 1973.

Rabies is a deadly virus that attacks the nervous system and is spread through the saliva of an infected animal, usually through a bite. In different regions of the United States, distinct variants of rabies are more common depending on which animal is most likely to harbor the virus. In California, bats and skunks are most susceptible to the disease, which is why bat and skunk rabies variants are most common. Other mammals, such as coyotes, dogs or cats, can still get sick from bat or skunk variant rabies. But what worries public health experts is the possible arrival of an unexpected variant of rabies that could spread widely among a new animal population.

Dr. Ryan Wallace, a veterinary epidemiologist at the CDC, told SFGATE that if raccoons test positive for a variant of raccoon rabies, it could trigger a multimillion-dollar federal and state response to combat this newly arrived disease strain and reduce the risk of human cases.

“Raccoons aren’t too afraid of humans, or at least of living in human habitats,” he said. “When a rabies virus spreads to a new species, especially one that has such close ecological relationships with humans, you can see a drastic increase in human exposures.”

Sick raccoons roaming a California yard are just the latest indicator that the rabies virus may be on the rise, not only in California but nationally. In September, the CDC reported a 76% increase in the number of people receiving post-exposure treatment for the virus. And in California, state authorities said the number of rabid animals found had broken a 28-year record.

However, delays in analyzing national data mean state and federal experts still don’t know whether or where this deadly disease is actually on the rise.

Among viruses, rabies stands out for its ability to infect and kill any species of mammal.

Dr. Monica Gandhi, an infectious disease expert at UC San Francisco, called the virus, which attacks the nervous system, “very, very scary.”

“It goes straight to the brain,” she said. An initial headache then leads to horrific symptoms, including seizures, paralysis and “rapid neurological changes, behavioral changes, hallucinations, delirium,” Gandhi said.

The disease is almost 100% fatal in humans and animals if they develop symptoms. But people exposed to rabies can receive a vaccine or immunoglobulin injections after exposure that stop the virus from replicating, saving their lives.

In the United States, 100,000 animals are tested each year by public health laboratories and approximately 4,000 animals are found to be rabid. On average, fewer than 10 people die from this disease each year. The last reported death in California was in 2024, when a Merced County art teacher was infected after finding a bat in her classroom and taking it outside.

Although there hasn’t been a confirmed human case in the state in years, California’s wildlife hasn’t been so lucky. At least 368 rabid animals have been found in the state so far this year, the highest number since 1998. The majority of rabid animals were found in Southern California and almost all were bats or skunks.

Beth Deines, a spokeswoman for the California Department of Public Health, said that despite the increase in wild rabies detections, the risk to the public remains low.

“The precise reason for this increase is not yet known, but rabies detections in wildlife can vary from year to year and by season,” Deines said in an emailed statement. “There is currently no evidence that rabies has spread beyond the bat and skunk populations in which the disease is routinely detected in California. »

Shannon Bennett, chief scientific officer of the California Academy of Sciences, said it’s unclear whether more animals are actually getting sick or whether more people are bringing in sick animals for testing.

“This is all passive (testing) by the public,” Bennett told SFGATE. “I don’t think anyone questions the true prevalence of rabies in bats when they go out and sample wild populations.”

Bennett said other factors that could explain the increase are the spread from urban areas into wildlife spaces and potentially even climate change, with warmer temperatures helping viruses replicate more quickly.

“There is no doubt that global warming makes viruses and other microbes really happy,” she said.

Wallace confirmed in an emailed statement that the two rabid raccoons discovered in SoCal tested positive for the bat variant of the virus, which is a good indication that a new raccoon-specific strain has not emerged in the area. But Wallace noted that two sick animals merit “close monitoring” since “repeated introductions increase the risk of raccoons becoming a new reservoir host in the Los Angeles area.”

The large number of detections in California comes amid signs that the virus may be on the rise in other parts of the United States.

In September, the CDC issued an alert about a dramatic increase in the number of people receiving post-exposure treatment for rabies. The study found there was a 76% increase in the number of people receiving rabies immunoglobulin injections, given after possible exposure to prevent replication of the virus. The study also found a 33% increase in the number of people who received the rabies vaccine compared to the previous year.

Wallace said CDC researchers saw a dramatic increase in numbers in May and June and that rabies vaccine sales remained high at least through early October.

“We can’t tell from this data source whether the phenomenon is widespread across the United States, localized to one region, nor can we say what species is causing it,” he said.

Wallace said the researchers turned to a big language artificial intelligence model to extract media reports of rabid animal detections in the United States, which showed a “widespread increase” in rabies exposures in California, Indiana, Ohio and Maine.

“The only signal we’re getting from a species perspective is a slight increase in bat numbers,” he said.

Wallace said people concerned about rabies exposure should never handle dead wildlife and always keep their animals up to date on their rabies vaccinations. Anyone who comes into contact with bats should seek medical attention, as a bat’s teeth are very small and people may not notice that they have been bitten.

In recent years, the CDC has developed sophisticated models that can analyze data from county and state public health reports and look for unusual activity. Wallace said these tools have identified a rabies outbreak in Texas in 2023.

But since the start of the Trump administration, the CDC has faced significant cuts and lost about 30% of its staff. Wallace declined to speak directly about funding, but said the 130 labs that test 100,000 animals require “sustained maintenance, and that also requires sustained effort.”

“When data flows properly, we have some really interesting tools,” he said. But he acknowledged that these tools and systems “are not up to date at the moment.”

The last rabies surveillance report released by the CDC was in 2024, with no current timeline for release of the 2025 report.

“We are a little over a year behind the increase in data flow and we are able to confidently answer a question like: ‘What is the national trend in rabies?’ “, Wallace said.

That doesn’t mean the United States is totally blind to rabies trends, because “state and local health departments are experts at surveillance in their jurisdictions,” he said. But Wallace acknowledged that “broader regional and national epidemiological trends are more difficult to identify in a timely manner.”

Dr. Matt Willis, an infectious disease expert and former Marin County public health official, said California’s strong public health system means the state is unlikely to miss major local rabies trends, but said a hobbled CDC could mean missing larger viral trends.

States “count things in different ways, and it becomes really difficult to actually see what’s going on because you end up with sort of an apples and oranges comparison from state to state,” Willis said.

Even if the CDC eventually addresses the backlog of data and analysis, Willis said the delay is concerning.

“If they’re that far behind, it’s possible there’s a much bigger problem that we’re just not seeing,” he said.