California Health Departments Warn of Leptospirosis Spike in Dogs
Health departments across California, including in the Bay Area and Los Angeles, have issued warnings regarding a spike in leptospirosis cases in dogs. This highly contagious bacterial disease can be fatal to dogs if untreated and, in rare instances, can transmit to humans.
About Leptospirosis
Leptospirosis, often referred to as 'lepto,' is a bacterial infection that can severely damage the kidneys and liver in both dogs and humans.
- Transmission: Animals and humans can contract lepto through contact with contaminated water, soil, mud, or urine from infected animals, primarily rats.
- Symptoms in Dogs: Increased thirst, urination, decreased appetite, lethargy, vomiting, and reluctance to move.
- Symptoms in Humans: Typically flu-like symptoms.
Current Situation and Risk Factors
Veterinarians in the Bay Area, such as Dr. Katherine Geating of the San Francisco SPCA and Dr. Kim Carlson of Lenity Vet Specialists + Emergency Care in San Mateo, report a significant increase in cases. Warnings have been issued across the Bay Area down to Los Angeles County.
The city of Berkeley issued a public health alert after an outbreak at a homeless encampment.
Transmission spikes during rainy periods. Standing water, particularly in areas like dog parks where water sits in grass, can create environments with high concentrations of the bacteria. The bacteria can remain viable in standing water for 30 days or longer.
Dogs licking their paws after walking through contaminated water can easily contract the disease. Small children are also at risk if they touch infected animal paws and then their mouths.
Human Cases and Tracking
Leptospirosis is a zoonotic disease, meaning it can transfer from animals to humans. While human cases are considered rare, several California counties have reported them. San Francisco reported one human case this year, and San Mateo County reported two cases in 2018 and 2024.
Tracking of animal lepto cases is not uniformly required by state or local health departments in California, though some jurisdictions like Santa Clara and Los Angeles counties do track them.
A past outbreak in Los Angeles County in 2021 was linked to dog boarding facilities and dog parks, resulting in hundreds of cases, 13 dog deaths, and 91 hospitalizations.
Prevention and Treatment
Early diagnosis and treatment are crucial for affected animals.
Positive cases require isolation, appropriate antibiotics, and urinary catheterization to prevent further spread within veterinary facilities.
The leptospirosis vaccine is the best protective measure for dogs, requiring an annual booster for full effectiveness.
Untreated pets can shed bacteria for weeks to months, while appropriate treatment can stop shedding within a few days to a week. Owners who suspect their pet has been exposed or shows symptoms should seek veterinary care immediately.