Humans become involved in the natural cycle of environmental disease agents when they are exposed to pathogens either by direct contact with infected wildlife, as with rabies, or when they are bitten by a mosquito or tick that has previously fed upon an infected animal, as with West Nile virus or Lyme disease. Humans are bystanders in these environmental events, but the consequence of infection can be devastating, and even fatal. Such is the situation we are now facing with the threat of West Nile virus.
The introduction of a foreign insect-borne virus, never before seen in the Western Hemisphere is a public health threat unprecedented in modern times. It is reminiscent of the introduction of yellow fever and bubonic plague in past centuries. This event has three possible consequences: It could simply disappear and represent a kind warning from Mother Nature that there is more to come. It could establish itself and repeat the events of last summer. Or, it could explode into a raging epidemic that spreads far beyond the confines of New York and Connecticut. The preponderance of evidence suggests that West Nile virus is not going to go away by itself and therefore we must be prepared for the remaining alternatives.
We were woefully ill-prepared for this epidemic of West Nile virus. We were not aware of an epidemic until some forty suspected cases filled New York City hospitals. We did not even know what virus was causing the epidemic until a month after people had already become ill and some had died. We did not know where the infected mosquitoes were and, consequently, ten million people were exposed to pesticides in an attempt to control the epidemic by indiscriminate aerial spraying of the entire New York City metropolitan area, not just once, but twice. Our lack of preparedness was obvious and costly.
These events, as shocking as they may seem to the general public, were predicted and warned by the scientific community. Two reports from National Academy of Sciences warned of a decaying public health infrastructure, particularly in reference to insect-borne diseases. The first report, "Manpower Needs and Career Opportunities in the Field Aspects of Vector Biology" published in 1983, warned of a serious manpower shortage in the field of vector biology, the study of insects that transmit human diseases. This report was totally ignored by Congress and the responsible federal agencies. Consequently there are now very few professionals in government or academic institutions with the appropriate knowledge and training to address the threat of insect-borne diseases. The second report, "Emerging Infections: Microbial Threats to Health in the United States" published in 1992, warned of the potential for the introduction of foreign pathogens and the degradation of public health infrastructure to combat such introductions. This report was taken more seriously by Congress and some federal agencies, but the response has been neither adequate nor timely, as is evidenced by recent events with West Nile virus.
What must be done to prevent a recurrence of last summer's events and to prevent similar events from occurring in the future? In the short term, every conceivable effort must be made to prevent West Nile virus from re-emerging next spring. It is quite likely to survive the winter months, either in infected wildlife or within the millions of mosquitoes hibernating in buildings and tunnels in the New York City metropolitan area. Immediate efforts should be made to find and destroy any infected mosquitoes that may be now overwintering. Heroic efforts must be made next spring to find the virus in mosquitoes or wildlife and to focus mosquito control efforts on containing the virus before humans become infected. A preemptive strike on certain mosquito species known to be capable of transmitting the virus should initiated early in the spring and directed at larval stage where environmental impact of insecticide usage would be minimal. Every conceivable effort must be made to control virus transmission early enough to prevent human infection and avoid the use of widespread aerial insecticide application to control a epidemic in humans. A repeat of last season's response must be avoided at all costs.
In the long term, we must strengthen the public health infrastructure to effectively and intelligently combat the threat of new and re-emerging diseases. If West Nile virus was a test of our response capabilities, we have failed miserably. Research is needed to better understand the human threat of infectious diseases that originate from the environment. This research should be interdisciplinary and include epidemiology, microbiology, entomology and, most importantly ecology. Government agencies responsible for the funding of peer-reviewed research on vector- borne diseases must be given increased resources to accomplish this goal. The training of a new breed of scientists, blind to interdisciplinary boundaries, and comprehensively trained both in the medical and environmental sciences should begin immediately in order to staff the increasing demand for expertise in government and academic institutions. Academic research institutions and government agencies at all levels should form working partnerships to integrate resources focusing upon this specific problem.
Epidemics of insect-borne disease are preventable. We have eliminated the threat of epidemic malaria, yellow fever, and bubonic plague in this country years ago, but we have left our guard down against the threat of new diseases, such as West Nile virus. Armed with new knowledge from academic research, and the will of responsible government agencies to refocus and integrate prevention efforts, we can regain our capacity to combat new disease threats from the environment and look forward to an improved quality of life in the next millennium.