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Daily News Archive

West Nile Finally Arrives in California
(Beyond Pesticides, October 30, 2003) Two people in California, one in the South and one in the North (near Sacramento), have now been identified as having West Nile virus (WNv) - the first locally-contracted cases this year. Both are safe and have been sent home from hospital. In anticipation of a full outbreak next season, the state is actively encouraging extensive surveillance and prevention.

Government and public health officials have expected the arrival of the virus since at least last August when the first "sentinel" chickens and mosquitos tested positive in Southern California. Since then a number of bird species and other animals have tested positive for the virus in various counties all along the state.

Lyle Petersen, Acting Director of the division of vector-borne diseases at the Center for Disease Control and Prevention (CDC) warned California that it would be hard hit by the virus next season, according to a story this month by Pest Control Technology. Petersen also said that California would receive more money from the CDC to improve surveillance (the tracking of mosquito populations and breeding sites) and public education to prevent people from being infected.

The virus has moved steadily down the Eastern seaboard toward the west since the first cases in New York in 1999, and has been expected to show in California for some time. Colorado has set off alarms in the west with a rapid increase of human cases at 2170 with 44 deaths so far this year, up from 14 cases and zero deaths last year. Other western states, including those bordering California, show low numbers this year, between 0-4 cases, according to the CDC.

In addition to wide scale surveillance, some counties in Southern California took preventative steps earlier this month by dropping bacteria pellets containing the biological pesticide, B.t.i. (Bacillus thuringiensis var. israelensis), on mosquito larvae. (See Daily News story.)

Considerable warnings ensued in the media last year about this being the worst season ever for West Nile, and although the final numbers are still out, human cases of West Nile have surpassed last year's numbers, yet deaths have not. Last year there were 4156 human cases reported with 284 deaths and as of October 29 of this year, 7386 cases have been reported with 155 deaths.

Though one can only speculate as to why the deaths did not jump as suspected, many believe that improved testing led to increased numbers of cases found, while better public education and awareness caused people with severe or prolonged symptoms to seek treatment sooner. Since most WNv cases show no symptoms and go uncounted (up to 80%), the CDC confirms that less than 1% of those infected will suffer severe symptoms (such as brain swelling due to meningitis or encephalitis) or death. As deaths have only occurred in people over age 50, those populations should be particularly careful and seek treatment should symptoms appear.

It appears for now that California has been on the right track for combating, and preventing, a severe outbreak by taking preventative steps and keeping mosquito populations at least well-monitored if not under control. Not helpful however, will be media reports that conjure feelings of panic rather than precaution and focus on the "deadliness" of the disease rather than the actual likelihood of death. Public outcry and panic can lead local officials to make a rash yet visible decision to qualm fears by enacting indiscriminate spraying of toxic pesticides over urban and rural populations and waterways which are at best ineffective and costly, and at worst, hazardous to public health and the environment.

For the majority of states, October marks the end of the mosquito season. If pesticide spraying is continuing in your community or state ask your local officials two questions: Are temperatures falling to 50 degrees Fahrenheit during the day or night? (which renders mosquitos completely inactive), and is the threat of a West Nile outbreak in these late weeks high enough to warrant the threat to human health and environment posed by the spraying of pesticides?

For more information on the West Nile virus, prevention, management and activism (including example letters to local officials or editors), see Beyond Pesticides' program on Mosquitoes and West Nile.