Berkeley death from rat-linked infection serves as ‘wake-up call,’ expert says

Months after Berkeley warned residents that rats carrying leptospirosis had been found near a homeless encampment in the city’s Harrison Street corridor, officials have confirmed the city’s first human cases in more than a decade, including one fatal infection.

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In a public health update released Wednesday, Berkeley officials said a person died in May after contracting leptospirosis while living in a recreational vehicle that was “severely infested” with rats. Another person who lived with the deceased also became infected but survived after a lengthy hospitalization. The first person died shortly after being hospitalized. Officials said both delayed seeking medical care for weeks or possibly months after becoming ill. 

City officials described the fatal case as an “extreme situation.” Vector control crews removed nearly 200 rats from the RV before it was ultimately towed away and destroyed. The vehicle was parked about a mile from the Harrison Street encampment that has been the focus of Berkeley’s ongoing leptospirosis response.

Dr. Peter Chin-Hong, an infectious disease expert at UC San Francisco, said the sheer number of rodents increased the likelihood of exposure to infected animals.

“The more rats you have, the more urine you might have, and you increase the chance of at least one of the rats having infection,” he told SFGATE. “If you just had one rat, it’s like playing rat roulette.”

In response to the death, Berkeley Public Health has issued new guidance urging medical providers to consider leptospirosis when treating patients who have been exposed to rats and develop compatible symptoms. 

Chin-Hong said the recent case illustrates a paradox of leptospirosis: It can be life-threatening if missed but is generally treatable when identified early.

“Nobody should die of lepto,” Chin-Hong told SFGATE. “It is a bacteria. It is treatable by antibiotics that every hospital has.”

The challenge, he said, is that many clinicians rarely encounter the disease and patients often don’t seek care during its early stages.

“People misdiagnose it because it’s not something that’s very common in the Bay Area,” Chin-Hong said. “You kind of have to diagnose it or suspect it to treat it the right way.”

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Leptospirosis is spread through contact with the urine of infected animals, particularly rats. The bacteria can enter the body through the eyes, nose, mouth or breaks in the skin. Symptoms often begin with fever, chills, headache, muscle aches, nausea and vomiting before potentially progressing to severe disease affecting the kidneys, liver, lungs and other organs.

“It’s a two-part illness,” Chin-Hong said. “The early phase is kind of like flu-like symptoms.”

According to Berkeley’s clinical guidance, the disease can appear anywhere from two to 30 days after exposure, with most cases developing within one to two weeks. While many infections are mild, about 10% can progress to severe illness that may cause organ failure.

The city’s update noted that the human cases occurred outside the geographic risk zones Berkeley established earlier this year around the Harrison Street corridor. Officials have since abandoned those zones and shifted to a broader strategy focused on living conditions that facilitate transmission, particularly environments with heavy rat infestations. 

Although the death has raised alarm, Chin-Hong stressed that leptospirosis remains uncommon and that the overall risk to most residents remains low.

“People shouldn’t be panicked,” he said. “But I think it’s a wake-up call that it’s in our backyard.”