California's Drought Could Increase Health Risks, Experts Say

The proliferation of West Nile virus is just one possible outcome.

ByABC News
April 9, 2015, 3:27 PM

— -- The ongoing California drought could cause more problems for state residents by creating favorable conditions for dangerous infectious diseases previously limited to hotter, drier climates, experts said.

The California Department of Public Health announced this week the state had a record-breaking number of deaths related to the mosquito-borne West Nile Virus in 2014, with 31 fatalities recorded. And 801 cases of West Nile Virus were reported in 2014, the second-highest number of cases ever recorded, second only to 2005, where there were 800 reported cases.

The ongoing drought across much of California might have exacerbated cases, state health officials said, noting that areas with stagnating water become prime spots for mosquitoes to lay eggs.

A record number of birds were found to have the virus as well, with 60 birds testing positive for West Nile, health officials said.

“As birds and mosquitoes sought water, they came into closer contact and amplified the virus, particularly in urban areas," California Department of Public Health Director Dr. Karen Smith said in a statement. "The lack of water could have caused some sources of water to stagnate, making the water sources more attractive for mosquitoes to lay eggs."

Officials also said warmer temperatures might have led to an especially long mosquito season.

In addition to West Nile, the arid conditions could also mean increasing cases of Valley Fever in the state, health officials said.

The potentially fatal disease is caused by a fungus called Coccidioides that can grow in the soil and that can spread in the air through spores if soil dries out. While more than 60 percent of people exposed to the spores don't have symptoms, people who start to develop the disease can have cough, fever, headache and in rare cases it can lead to death, experts said.

Art Reingold, professor of infectious disease at the University of California, Berkeley, said it's possible that climate change could lead to ongoing drier conditions that would be favorable for more Valley Fever infections.

"It’s so clearly related to soil and dust -- dust getting into the air ... then that’s quite plausible," he told ABC News.

Rates of Valley Fever infection steadily increased between 2001 and 2011, when reported numbers peaked at 5,182 cases before dropping off again, according to the state health department. In 2013, there were 3,298 reported cases of the disease. The increase in numbers has not officially been linked to drought conditions.

John Galgiani, director of the Valley Fever Center for Excellence at University of Arizona, said that in Arizona, rain can initially help grow the fungus in the soil but if it's followed by months of arid weather, the spores can start to float in the area and even travel hundreds of miles.

"There’s reason to think that it should apply also to California," he said.