Endangered SF species among animals affected by emerging diseases

The first results of our study are in, and they paint a different picture than we previously understood, CDFW scientific aide Raquel Elander said in a Thursday news release. Prior to this project, we only had two instances of the pathogen in California.

The first two cases in the state were identified in a California kingsnake from Amador County and an invasive Florida banded water snake collected in Sacramento County in 2019, prompting CDFW scientists to launch another three-part study. years in collaboration with the Wildlife Epidemiology Lab of the University of Illinois.

The results based on just the first year of the study were staggering. Skin swab samples collected between July 2021 and October 2022 yielded positive results for the disease in nine additional species in 10 counties in the San Francisco Bay Area, Sacramento Valley and San Diego. These species included the aforementioned San Francisco garter snake, northern Pacific rattlesnake, western yellow-bellied racer, Pacific gopher snake, valley garter snake, giant garter snake, and a non-native milk snake as well as other California kingsnakes, including at least one from Marin County.

The San Francisco garter snake is said to be the most beautiful snake in North America, with its bright blue underbelly and distinctive red, black, and white stripes. It has been listed as federally endangered since 1967 and inhabits only wet, swampy areas along the San Francisco Peninsula from northern San Mateo County to the base of the Santa Cruz Mountains.

Visible signs of fungal snake disease include crusting or peeling scales, abnormal bumps under the skin, eye opacity not associated with moulting, and facial disfigurement that can make it difficult for them to catch prey, resulting in emaciation and death. However, some of the snakes that tested positive for the disease in California showed none of these symptoms, leading scientists to believe they may have been asymptomatic carriers or were experiencing mild or early-stage infections.

The disease has been detected in more than 30 snake species worldwide since 2008, with a substantial increase in reported cases over the past six years, according to the US Geological Surveys National Wildlife Health Center. In 2016, USGS researchers released a study that revealed the disease had been widely identified in the eastern half of the United States and was the leading cause of skin infections in wild snakes. They believed it was more widely distributed than documented cases suggested due to limited efforts to monitor the health of snake populations and the possibility that fungal snake disease might be underreported in populations that developed minor symptoms or were not commonly affected.

Many snake populations are already in decline, and the recent emergence of SFDs could accelerate this decline, causing some species to disappear completely from some locations, the National Wildlife Health Center said in 2018.

Fungal snake disease can be transmitted from a contaminated environment or from snake to snake. There is no evidence that it can make humans ill, but it is possible that people transfer the fungus to snakes by handling them directly or by carrying contaminated dirt and debris on their shoes. Captive snakes can also carry and spread disease if they escape or are intentionally released into the wild, putting other native and endangered species at risk.

CDFW is asking the public to keep away from wild snakes and avoid touching them, even if they appear injured, sick or dead. If a snake grazes your shoes while hiking, sanitize them as soon as possible using a 10 percent bleach solution with a minimum exposure time of five minutes to effectively kill the fungus. Persons with a fishing license that can be used to catch snakes are advised to sanitize their hands using alcohol-based hand sanitizer or wear disposable nitrile gloves and change them frequently.

It is not known how the disease will continue to affect several populations of snakes in California. People can report sick or dead snakes to the CDFW on the department’s website.