The following is an invitation to respond to Clark Hoyt.
After a winter of terrible snowstorms, California’s northern portion can expect another dismal spring, though scientists say the disease causing the terrible outbreaks in the Sierra Nevada can be contained within the El Niño climate pattern.
The idea of an El Niño is familiar to Californians — that an unusually warm Pacific ocean causes unusual atmospheric conditions, and sometimes shifts droughts and intense fires to areas in the far south or north of the state.
Calivor virus, which causes severe respiratory illness, claimed three lives in recent weeks, more than doubling the typical death rate. In the last five weeks, Santa Clara County’s Calivor virus coordinator, Eric Bodenstein, has gotten reports of 22 cases in the northern half of the county — mostly in Santa Clara and Alameda counties. These are not Yosemite to the west or Death Valley to the east, Bodenstein said — these are more densely populated cities of 300,000 and more.
“It’s a very unusual situation,” he said.
However, risk coordinators said there are two reasons the virus is spreading rapidly: One, it’s closely related to the Crimean-Congo hemorrhagic fever virus that causes epidemics in areas of Africa in the winter, which means it tends to be a winter-only virus in California. Two, the virus, which only kills some patients, is easily transmitted from rodents to people through contact.
In a normal winter, the average number of cases reported in California’s northern county ranges from a few hundred to a few thousand.
People who contract the disease get flu-like symptoms and can have headaches and vomiting. It can also spread to humans via contact with animals. It is almost always fatal in infected humans.
The disease was previously confined to parts of Northern and Central Africa. The more recent onset of the spread and the sudden nature of the deaths in California are both rarer. Bodenstein said this virus is not as common as its cousins in other regions — which suggests that it’s causing more deaths than the disease ordinarily causes. The bugs are the same from year to year — the only changing factor is the climate and the present El Niño.
Mark Bowden, an epidemiologist and public health expert at the Scripps Institution of Oceanography in La Jolla, California, described the state’s vulnerability to the parasite as small. He said that it would take more than a few epidemics of larger proportions to affect California’s overall population, which was growing.
While the link between Calivor virus and West Nile virus is not solid, Bowden said it was likely that the virus has some cousins that caused more severe illnesses.
If the El Niño were to continue or worsen, Bowden said, the chance of additional epidemics would rise.
Bowden said there was no sign of what he called a public health emergency in Santa Clara County — at least, not on the public health front.
“It’s too early to say [that] the county’s had any additional impacts,” he said. “We don’t see anything. We’re still reviewing cases of illness. That doesn’t mean we haven’t or won’t have additional cases.”
Bowden said the disease did not show any discernible animal-to-human transmission.
However, Pat McKone, director of state epidemiology at the California Department of Public Health, said that though there is no direct animal-to-human transmission, it’s possible that the disease is hiding in the soil and that land ants — or even raucous aphids — are bringing it indoors to get closer to people.
However, she said, even if the source of the disease weren’t ants or raucous aphids, the windy weather could enable disease to enter people’s homes. There are medications to treat the disease and prevent it, she said.
Although ant bites aren’t suspected to be the source of the outbreak, officials with the U.S. Centers for Disease Control and Prevention who are currently working on a possible outbreak in Minnesota still recommend wearing a mask when near any open-air sources of animal waste or excrement — including woods, fields, or even farmlands. People should also limit contact with rodents, she said.