Bubba’s Story: Health officials warn of leptospirosis, a highly contagious deadly bacterial disease affecting dogs and people

SAN FRANCISCO (KGO) — Health departments across California are sounding the alarm about a highly contagious bacterial disease that can be deadly in dogs if not treated. And in rare cases, it can spread to humans.

It’s called leptospirosis — and it’s actively spreading right now in the Bay Area and parts of the state, including Los Angeles.

7 On Your Side’s Stephanie Sierra’s dog, Bubba, contracted the disease and fought it for weeks.

This was Sierra’s sweet dog, Bubba. Out of nowhere, he got sick.

They went to numerous emergency rooms trying to help him, and were left with no answers — until they met a vet who knew exactly what to test for.

What happened to Bubba

Nine-year-old Bubba never missed a meal, so Sierra knew something was wrong when he suddenly stopped eating.

The happy-go-lucky German shepherd-border collie mix went from trotting through the park to suffering from anorexia within days.

And they had no idea why.

They took him to the ER at the San Francisco SPCA. Within 20 minutes, Bubba was diagnosed with leptospirosis — also known as “lepto.”

It’s a highly contagious bacterial infection that can affect both dogs and humans, severely damaging the kidneys and liver.

San Francisco SPCA veterinarian, Dr. Katherine Geating, said animals or humans can contract lepto through contact with contaminated water, soil, mud, or urine from infected animals — namely rats.

“Lepto is a really important disease. It’s one of those things — every single day, every single appointment, I’m educating clients on how serious it is,” she said. “Here in the Bay Area, I tell owners any puddle of water means your dog can be exposed.”

Veterinary surgeon Dr. Kim Carlson is seeing a spike in cases at her San Mateo-based emergency clinic, Lenity Vet Specialists + Emergency Care.

“We’re definitely seeing a lot. We’ve had three cases just in the last couple of weeks,” Carlson said.

California veterinarians are sounding the alarm across the state, with local warnings issued across the Bay Area down to new cases reported out of Los Angeles county. Last month, the city of Berkeley issued a public health alert after staff discovered a lepto outbreak at a homeless encampment in the city.

Doctors say transmission spikes when it rains.

“Every single year when it starts raining here in the Bay Area, I see most of my lepto cases,” Geating said. “When water sits for a long time, so you think of your dog park where there’s a field and water is just sitting in the grass. That can create a biofilm, and then you can have a really high concentration of leptospirosis infection in that still water.”

Public health officials warn the dangerous lepto bacteria can stay alive in standing water for 30 days or longer, which is why the highly contagious bacteria can pose a threat at dog parks.

“So, if a dog were to walk through water, lick their paws — easily they could pick that disease up. I think of small children. If they were theoretically to touch their dogs’ paws and their mouth, that’s what we worry about,” Dr. Geating said.

The potential threat to humans

Leptospirosis is considered a “zoonotic disease”…

“Meaning that animals can transfer it to us,” Dr. Carlson explained.

“We have a current outbreak with concerns with humans earlier this month,” Dr. Geating said.

The data shows human cases are considered rare, but several California counties are reporting them — including one case in San Francisco so far this year.

The LA County Health Department reports fewer than five human cases in 2026. In San Mateo County, two lepto patients were reported in 2018 and 2024.

San Francisco’s last lepto outbreak in dogs was during the winter storm of 2017. But the impact of the outbreak is unclear, in part because regulations don’t require the state or local health departments to track and report lepto cases in animals. However, some jurisdictions still do, like Santa Clara and Los Angeles counties.

In Santa Clara County, at least one dog contracted lepto last year. In Berkeley, at least two dogs contracted lepto so far in 2026. And in Los Angeles, at least six dogs have contracted the disease since January.

According to the LA County health department, the last lepto outbreak in 2021 started out of dog boarding facilities with hundreds of cases, resulting in 13 deaths and 91 dogs being hospitalized. Roughly half of those cases reported going to dog parks.

“If you’re worried that your pet might have it — the first clinical symptoms and the most common ones that we see are increased thirst, urination, and decrease in appetite,” Geating said.

Public health officials say humans typically experience flu-like symptoms, whereas other symptoms to watch in dogs include lethargy, vomiting, and reluctance to move.

Bubba had all those symptoms.

Due to the quick diagnosis from the San Francisco SPCA, Bubba was transferred to the ER at Lenity for aggressive treatment.

“If they are positive for lepto, then they must go into isolation. Be started on appropriate antibiotics. And have a urinary catheter placed so that their urine is contained so that you’re not exposing personnel in the hospital,” Dr. Carlson said.

After days in isolation at the ER, Bubba didn’t give up. Sierra was rooting him on, as he was tied up to antibiotics. And the little boy kept fighting. Bubba ultimately made it out of the hospital.

There’s no doubt the compassionate teams at the San Francisco SPCA and Lenity Vet Specialists in San Mateo extended his life. The loyal 49ers fan got to watch one last game and make a final visit to his favorite place, Chrissy Field, where he’s affectionately known as “Mr. Mayor.”

But what they didn’t know leading up to this was that Bubba was suffering from chronic liver disease. His vets say the additional hit to his liver from the lepto infection ultimately took his life a few weeks later. It’s really important if you suspect that your pet has come into contact with another animal that was diagnosed and is showing any of these clinical signs that you see your veterinarian right away.

Early treatment and vaccinations are crucial

Carlson said if a pet is not treated and has lepto, they can continue to shed that bacteria for weeks to months. But, with appropriate treatment, shedding can stop within a few days to a week.

The best thing you can do to protect yourself and your pup is the leptospirosis vaccine, which requires an annual booster to be fully effective.

Take a look at more stories and videos by 7 On Your Side.

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