Berkeley leptospirosis outbreak turns deadly after human cases linked to rat-infested RV

A deadly rat-borne disease outbreak in Berkeley has claimed its first human victim in more than a decade — and health officials say the shocking case involved an RV so overrun with rodents that nearly 200 rats had to be removed before the vehicle was destroyed.

Berkeley officials confirmed this week that one person died in May after contracting leptospirosis, a potentially fatal bacterial disease spread through the urine of infected animals, particularly rats. A second person who lived with the victim survived after a lengthy hospitalization.

The pair lived together in an RV about a mile from a sprawling homeless camp in North Berkeley that has been at the center of an ongoing leptospirosis outbreak among rats and dogs since late 2025.

City Manager Paul Buddenhagen said the two occupants were using the RV to trap, feed and breed wild rats. Officials described the vehicle as “severely infested” with rodents.

Vector control crews removed nearly 200 rats from the RV before it was towed away and destroyed.

The two people “fell sick, but they did not seek medical care for weeks and possibly months,” Buddenhagen wrote in a memo to the City Council. That delay “is thought to have contributed to the severity of their disease.”

The victim died shortly after being hospitalized, while the second resident eventually recovered.

Dr. Peter Chin-Hong, an infectious disease expert at UC San Francisco, said the sheer number of rodents dramatically increased the risk of infection.

“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.”

Leptospirosis typically begins with flu-like symptoms, including fever, chills, headaches, muscle aches, nausea and vomiting, but can progress into life-threatening organ failure.

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

Despite the fatality, Chin-Hong stressed that the disease is usually treatable when caught early.

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

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