U.S. NEWS West Nile Infections Slam California Drought Blamed for Ripening Conditions to Spread Potentially Fatal Disease By JIM CARLTON Sept. 10, 2014 2:32 p.m. ET si.wsj.net/public/resources/images/BN-EM189_0910we_G_20140910142140.jpg An outbreak of West Nile virus in California has stricken nearly 250 people, more than twice as many as all of last year, and public health experts say the regions prolonged drought may be a factor. Here, a female mosquito that is one of the prime culprits in the spread of West Nile. REUTERS SAN FRANCISCO—West Nile virus infections are soaring in California, fueled by a drought that experts say has helped make the state the countrys hot spot for the potentially fatal disease transmitted by mosquitoes. As of Tuesday, there were 238 cases of West Nile virus reported in humans so far this year in California, compared with 117 at the same time last year and a five-year average of 74, according to state officials. So far this year, the virus is known to have killed nine people in California, compared to a total of 15 deaths in the state last year. There isnt a drug or vaccine to combat the virus. Contributing to the outbreak is the highest level of mosquitoes infected with West Nile virus ever detected in the state, said Ron Chapman, director of the California Department of Public Health. State officials, who expect the disease to spread, said the risk of infection is greatest later in the year, because mosquitoes contract the virus earlier in the year after sucking blood out of birds that are the diseases major carriers. We expect to see more people become infected as this is the time of year when the risk of infection is the highest, Dr. Chapman said. West Nile virus, which was first detected in Africa and entered the U.S. in 1999, is transmitted to humans by the bite of an infected mosquito. While most people dont suffer serious illness, state and federal health officials say less than 1%—particularly people over 50 and those suffering from diabetes and/or high blood pressure—have a greater risk of developing a serious neurologic disease such as encephalitis or meningitis. Besides California, West Nile virus cases are also spiking this year in Texas and Louisiana, but not in as great numbers, said Roger Nasci, chief of the arboviral diseases branch for the Centers for Disease Control. He said periodic outbreaks have hit different parts of the country over the past decade, and that Californias severe drought appears to be a factor in rekindling an epidemic there this year. He said there are fewer sources of natural water for virus-carrying birds, forcing them to mix more with mosquitoes around urban water sources. Drought does appear to contribute to elevated West Nile activity, because it does bring birds and mosquitoes together, Dr. Nasci said. Exacerbating the situation have been unusually warm temperatures that are conducive to more mosquitoes, said Fenyong Liu, professor of infectious diseases at the University of California, Berkeley. Orange Countys John Wayne Airport, for example, underwent a streak of more than 100 consecutive days of above-average temperatures earlier this summer. Orange County, south of Los Angeles and home to Disneyland, has emerged as ground zero of Californias West Nile virus epidemic, with 85 human cases—more than three times as high as any other county. Local officials realized they faced a bad year when their routine monitoring for the virus showed a massive cluster in birds and mosquitoes in the spring, said Jared Dever, spokesman for the Orange County Vector Control District. Around 80% of mosquitoes tested have the virus, county officials said. Most years, up to 20% of mosquitoes tested are found to carry the virus. The district has tried to reduce the threat by removing nonessential water sources, he said. For example, the district has contracted for airplane surveillance to identify backyard sources such as birdbaths or spas that can be emptied to remove a mosquito breeding location. For the countys many pools, the district has handed out mosquito-eating fish and an insecticide that kills the larvae. More controversially, the district authorized a program of fogging neighborhoods with pesticide to begin this week. But that has been suspended because weather conditions—such as the need for more wind to disperse the chemical—havent been right. Elsewhere, health officials are educating the public on avoiding the virus until the onset of seasonally cooler weather drives mosquito populations down. The best strategy is for prevention, Dr. Liu said. Wear a long-sleeved shirt and repellant. Write to Jim Carlton at jim.carlton@wsj
Posted on: Thu, 11 Sep 2014 23:55:33 +0000