Feature   |   Spring 2004

Urban Renewal

A spreading epidemic

A recent example is the U.S. outbreak of West Nile virus—a potentially fatal disease spread to people and animals through the bite of infected mosquitoes. While it has long been present in other areas of the world, West Nile did not reach the United States until five years ago. When the first case was confirmed in the summer of 1999 in New York City, public health officials nationwide began gearing up for West Nile's eventual and inevitable westward spread.

Animals often serve as sentinels, and this was the case with West Nile. Birds and horses were hit with the disease first. Confirmation that the virus had arrived in Indiana came in August 2001, when the Indiana State Department of Health's (ISDH) surveillance program for mosquito-borne diseases detected it in a crow. Later in the year, the first equine case was diagnosed.

The findings mobilized state and local health and sanitation departments, municipal governments, entomologists and veterinarians. Purdue Agriculture poured considerable manpower into working with public health officials and the pest control industry, as well as educating the public. Urban entomologists consulted with Indiana's largest cities, which already had organized mosquito control in place, and its smallest towns, which were often starting from scratch. “It was important to educate the towns that were new to mosquito control. Otherwise, they could have done more harm than good,” Bennett says.

Ralph Williams is one of the Purdue entomologists who help Indiana 's public health officials combat mosquito-borne diseases like West Nile virus. (Photo by Tom Campbell)

West Nile was found in only nine Indiana counties in 2001, but, by the next summer, the virus had reached all 92 counties. “It hit sooner, and we saw more cases than we expected,” says Ralph Williams, professor of entomology, an expert on disease-spreading insects and public health point person for Purdue during the outbreak. Williams and entomology professor John MacDonald assisted the ISDH, the agency responsible for initiating a statewide action plan for surveillance, mosquito control and disseminating information to the public.

"Ralph investigated reports of illnesses in horses and assisted with recommendations for mosquito control, as there were a large number of equine cases in 2002,” says Michael Sinsko, ISDH senior medical entomologist. “He also answered calls from reporters, spoke to groups and provided training. We had an entire state to cover, so the more people we had available to get the message out, the better off we were.”

MacDonald helped with the surveillance program, trapping and identifying mosquitoes, then sending them to the ISDH for testing. “ West Nile hit some areas of the state more severely than it did others,” Sinsko says. “The more people we had helping with the surveillance program, the better the picture we got of what was happening in different areas of the state.”

Nationwide, the 2002 West Nile virus outbreak is the largest arboviral epidemic recorded in the nation's history, with some 4,100 cases and 284 deaths. Indiana recorded 293 cases and 11 deaths, as well as more than 700 equine cases. In 2003, the state's numbers dropped dramatically to 47 cases and four deaths.

After an epidemic of a similar mosquito-borne virus 29 years ago, Indiana began putting a surveillance system in place that would enable the state to respond quickly to vector-borne diseases. An outbreak of St. Louis encephalitis swept the nation in 1975, infecting more than 2,000 people and killing nearly 100. The Midwest was particularly hard hit, and the outbreak remains Indiana's largest single-year, mosquito-borne epidemic, with 323 cases and 17 deaths.

It was in the wake of the 1975 epidemic that the ISDH tapped Sinsko as its first full-time medical entomologist to develop a statewide monitoring and response plan. A year later, after completing his doctorate at Oklahoma State University, Williams joined the faculty of Purdue's Department of Entomology, where he had done his undergraduate work.

In their 27-year working relationship, Sinsko and Williams have collaborated to educate and train public health officials, urban pest managers and the general public. Both are founding members of the Indiana Vector Control Association, which provides educational programming and helps coordinate efforts of state and local public health officials, university researchers, and representatives from the pest control industry.