It’s a rare bacterial infection normally found in the tropics which can cause everything from mild flulike effects, to in rare cases liver, kidney, and brain damage. Now, an update into an investigation of some cases in Ventura County shows it’s the largest recorded outbreak in the United States, with 19 confirmed.
"Leptospirosis is a bacterial infection that is fairly rare in the United States. It is a bacteria that is found in the urine of animals. It can be found in domesticated animals, cats and dogs, but also in wild animals, rodents and and potentially raccoons," said Dr. Uldine Castel, Ventura County’s Public Health Officer.
"It's spread from contaminated soil or water from that urine," said Castel.
The first cases were discovered last fall, but then an investigation showed it actually turned up in the county in January of 2024. The 19 cases involved agricultural workers.
"Everybody has recovered completely from the illnesses," said Dr. Castel.
In most cases, Leptospirosis can easily be treated with antibiotics, if it’s diagnosed early.
Once health officials realized the were dealing with a bacterial infection, they focused on two major questions: Where was it coming from, and what was causing it? They isolated it to some farms in the Oxnard area growing caneberries.
Caneberries are berries that grow on woody canes, like raspberries. "The common denominator was they (the infected workers) all worked in caneberries," said the health official. "How it's contracted is most likely through some abrasion, and it could be a very, very small, even what we could consider a micro abrasion in the skin, and the contact with contaminated soil or water."
Dr. Castel said the exposure most likely involved contaminated urine from rodents.
But, to figure out exactly what was going on, they needed to investigate. State Public Health officials helped with the fieldwork, and the federal Centers for Disease Control did lab testing.
Dr. Castel said they were able to eliminate a number of possibilities, narrowing down things to the hypothesis that exposure to contaminated soil or mud led to the infections.
The outbreak led to efforts to educate local clinics about how to spot the infections, and working with farmers to teach workers how to avoid exposure. It’s simple steps like wearing waterproof protective gear, covering cuts and scrapes to avoid exposure to the soil, and using soap and water if you come in contact with soil, or mud.
Is the outbreak over? The health official said they hope the answer is yes, but admits they aren’t sure.
"There have not been recent cases," said Dr. Castel. "Hopefully, prevention measures will continue to allow us to not have new cases. But, I don't want to pat ourselves on the back yet, because part of the issue with Leptospirosis is that it really likes tropical environments. It's been cold. And then, harvesting of the berries has been slow in the last months. We have not had new cases, and I hope that it is because prevention has improved."
Individual cases of the bacterial infection do sometimes show up around the United States, but they are usually linked to someone contracting it while visiting a tropical country.
