West Nile Virus, 2002

Dead birds may be the best indicators

West Nile Virus (WNV) has arrived in Maine, and like deer ticks and Lyme Disease, health experts believe it is here to stay and will spread throughout the state. “It’s not going away,” said Duane Gubler, Director of Vector Borne Infectious Diseases at the Centers for Disease Control, at a meeting of the Maine Bureau of Health’s WNV Working Group, a task force convened in 1999 to prepare for this eventuality. The multi-agency group, chaired by Kathleen Gensheimer, State Epidemiologist, includes representatives of several state departments, plus medical doctors, research scientists and veterinarians.

The positive WNV identifications occurred from August through October of 2001 in Portland, Cape Elizabeth, Sabbatus and South Berwick. The Bureau of Health (BOH) had scheduled a press conference to inform the public on Sept. 11.

In 1999, there were seven human fatalities from West Nile Encephalitis. In 2000 there were two, and in 2001 there were nine. No human cases have been detected in Maine.

Gubler and Andrew Spielman, SC.D, Director of the Laboratory of Public Health Entomology at the Harvard School of Public Health, shared their expertise about WNV with the Working Group in February to help its members and Dr. Dora Mills, Maine’s Director of Public Health, develop a plan for the BOH’s response in 2002 to the presence of WNV in Maine. During the past two summers, the Working Group instigated extensive programs of Bird Surveillance, testing dead birds for the virus; Mosquito Surveillance, to determine the types of mosquitoes living in Maine, with particular emphasis on locating those species known to transmit WNV to humans; Public Education, to emphasize ways residents can minimize their risk of contracting the virus; and Mosquito Control, to explore measures available and assess their environmental impact.

Now that WNV has arrived, questions for the group center on what proactive measures are important in each of these areas, what parameters the state will use to determine that WNV poses a public health problem, and, if that point is reached, what action should be taken.

Gensheimer has emphasized that healthy children and adults are at extremely low risk for illness from WNV. Most often the virus causes mild symptoms or none at all. Occasionally, more severe cases of West Nile Encephalitis occur in people well over 50 who already have compromised immune systems. This group is urged to take special precautions not to be bitten by mosquitoes.

Experts and members of the Working Group agreed that the best and first line of defense is public education and subsequent action by residents to clean up any areas of stagnant water. People are urged to keep lawns mowed and take measures to avoid being bitten by mosquitoes by installing window screens, wearing long sleeved clothes and using repellant. (A full list of recommendations is available on web sites given below and at town halls.)

The most controversial aspect of WNV policy, mosquito control, con- tinues to divide even the experts. They and members of the Working Group debated the pros and cons and the efficacy and risks of low volume aerial spraying of adulticides and the application of larvicides. Both are prohibitively expensive for widespread use. They discussed preventive action as opposed to waiting until a definite human risk is indicated by the presence of a certain number of dead crows, vector mosquitoes and human cases in a certain area.

Kathleen Magee of the Maine Toxics Coalition, and Will Sugg from Maine Environmental Policy Institute, expressed concern about the worldwide effect of spraying on humans and animals. Patrice Farry, Executive Director of Maine Lobstermen’s Association, whose members oppose spraying because they believe there was a connection between New York City’s intervention and the Long Island Sound lobster die-off in 1999, said after the meeting that she wishes she could believe the spraying or larvicides are not harmful to other animal life. She said she wants to see studies to the contrary or, at minimum, studies set up to assess the effect on lobster and other arthropod larvae in any coastal area where spraying is conducted.

Director of Public Health Mills, State Epidemiologist Gensheimer and members of state agencies like the DEP, Department of Marine Resources and Maine Forest Service have repeatedly said in interviews during the past two years that they are wary of spraying’s effect on the environment and consider it a last resort.

For further information about WNV, reporting dead birds and precautions residents should take, see www.state.me.us and type in West Nile Virus. Maine Environmental Policy Institute’s May, 2001 report, “Overkill, Using Pesticides to Control WNV Mosquitoes in Maine May Do More Harm than Good,” is available at www.meepi.org. The Dead Bird Hotline is 1-888-697-5846.