ENCEPHALITIS OUTBREAK

September 15, 1999
		Roger Nasci, research entomologist at the Center for Disease Control, and Neil Cohen, commissioner of Public Health in New York, discuss the growing concern over disease-bearing mosquitoes in New York and Louisiana. The Health Unit is a partnership with the Henry J. Kaiser Family Foundation.

Sept. 10, 1999: The art of Dying The AIDS Crisis. Aug. 23, 1999: Public health in Turkey after the Earthquake July 20, 1997: Treating Heart Failure July 16, 1999: A Bill of Health? July 8, 1999: An Alzheimer's Vaccine? Remaking Medicare June 24, 1999: Should doctors unionize? June 7, 1999: Mental Health Conference May 27, 1999: A Choice on Heart Disease Jan. 27, 1999: Treating Parkinson's Disease. Jan. 4, 1999: Long-term care. Oct. 30, 1998: Multiplying brain cells. March 12, 1997: Alzheimers findings The NewsHour's Health Spotlight. Browse the NewsHour's Health coverage.   Center for Disease Control New York Public Health	SUSAN DENTZER: For almost two weeks, New York City health officials have been waging an air and ground war against the mosquitoes that are spreading viral encephalitis. The disease causes a potentially fatal swelling of the brain, and has so far killed three city residents since early September. Meanwhile, eight other cases have been confirmed, and 86 suspected ones are under investigation. After the outbreak spread beyond a few neighborhoods in Queens and Brooklyn, helicopters, airplanes, and trucks expanded their spraying to all five of the city's boroughs. Mayor Rudolph Giuliani says the entire city will be sprayed over the next four weeks to prevent a more serious outbreak. MAYOR RUDOLPH GIULIANI, New York: There could be the possibility that even once this is in remission for a short period of time, it could come back again at any time until there is frost.
	Chemicals vs. infection
	SUSAN DENTZER: City officials have set up neighborhood command centers to hand out insect repellent. They've advised residents to remain inside with doors and windows closed during spraying. City officials insist the insecticides are safe, but many New Yorkers say they're more afraid of the chemicals than of the threat of encephalitis. This Central Park biker is one. CENTRAL PARK BIKER: Central Park is one of the few places we come to exercise on weekends, and spraying the park doesn't leave New Yorkers with much other alternative to exercise and stuff. So we're very strongly against it. SUSAN DENTZER: The type of viral encephalitis that has hit New York is called St. Louis Encephalitis, the most common variety of the disease in the U.S. It is caused by a virus thought to occur naturally in birds. Mosquitoes come into contact with the virus when they feed on the birds' blood. When they move on to human targets, the mosquitoes then transmit the virus to people. The virus enters the body's cells and spreads to the brain, where it causes swelling and interrupted blood flow. Most infected people never show any of the flu-like symptoms and recover on their own, but cases of severe infection can result in death. SPOKESMAN: The signs and symptoms in the next five to 15 days is what you want to watch for, okay. SUSAN DENTZER: Although common in many parts of the world, serious outbreaks of encephalitis are relatively rare in the U.S. Since 1964, just under 4,500 cases of St. Louis Encephalitis have been reported to the Federal Centers for Disease Control, that's an average of 128 cases annually. The last major epidemic occurred in the Midwest between 1974 and 1977, when more than 2,500 cases were reported in 35 states.
	Pesticides vs. infection
	JIM LEHRER: Elizabeth Farnsworth has more. ELIZABETH FARNSWORTH: And I'm joined by Dr. Neal Cohen, the New York City health commissioner, and Roger Nasci, a research entomologist with the Federal Centers for Disease Control. Dr. Cohen, put this in context for us. How serious a public health threat is this right now in New York? DR. NEAL COHEN: Well, although at this time the number of people who are affected by this virus seem to be relatively small, it's an important opportunity for the public health community to address the transmission of a vector-borne illness that requires a variety of ways to address it, to make sure that we're taking the necessary control measures, to provide sufficient information citywide so that citizens can reduce their potential exposure to mosquitoes and to let the public know that the dangers involved in the spraying and the insecticide that we are applying are so minimal, that they need not fear. We want don't want to reduce any chance of panic and overreaction. At the same time, we want people to think very carefully and clearly about their responsibility and the ways that they can prevent themselves from having this exposure. ELIZABETH FARNSWORTH: How can they prevent themselves from having this exposure? DR. NEAL COHEN: Well, naturally, since mosquito biting is occurring from dusk to dawn, we've advised the population to wear long sleeved shirts and long pants and essentially they can use insecticide, an Off product that has less than 30 percent Deet, to make sure that they don't put themselves in a position where they have unnecessary biting by mosquitoes, even though the number of mosquitoes that carry the infection we think are anywhere from 1 in 200 to 1 in 1,000 based on reports from previous outbreaks. ELIZABETH FARNSWORTH: Dr. Cohen, who's especially vulnerable to this? DR. NEAL COHEN: Well, the elderly and very young children because of somewhat immature or compromised immune systems are more likely to develop more severe forms of the illness. The majority of adults and young people would contract very mild cases. They may not even be aware that they have anything but a mild flu and those that do have a more severe form generally recover very well. But the elderly in large measure particularly with St. Louis Encephalitis, seem to be particularly vulnerable. ELIZABETH FARNSWORTH: And the key symptoms are? DR. NEAL COHEN: Well, we're seeing fever, a severe headache. And as the signs of irritation and inflammation of brain tissue progress, we can see altered states of consciousness, lethargy, confusion and in severe forms, it can be stupor and comatose. ELIZABETH FARNSWORTH: And Dr. Cohen, how high could the numbers go? What are you expecting at this point? DR. NEAL COHEN: Well, at this point it's very hard to throw a number out. We have 11 condition confirmed cases for sure. We're investigating 80 or so more. We're hoping that, given the spraying that we carried out, that we're on the down slope and that, as the climate changes, we're not going to see too many infections. But we need to take precautions and continue to inform the program... inform the public and take the necessary insecticide spraying and very careful application to make sure that we're really eliminating the mosquito population at this time. ELIZABETH FARNSWORTH: Roger Nasci, do you have anything to add, and especially on the possible numbers that could be involved? ROGER NASCI: Well, the... as Dr. Cohen indicated, it's very difficult to speculate about what may happen. We're hoping that the control operations that we have shown have been very effective in suppressing the mosquito population, will prevent any further transmission of the virus.
	Detective work
	ELIZABETH FARNSWORTH: You have experience with this because other cities like St. Louis, Chicago, and other places have gone through it this, right? But are they having trouble this summer? ROGER NASCI: Currently this is the only evidence of transmission of St. Louis virus to humans that's been reported around the country. ELIZABETH FARNSWORTH: Why do you think it happened? ROGER NASCI: There are some environmental conditions that make an area capable of supporting St. Louis Encephalitis virus, a mild winter, a wet spring and a hot, dry summer. And then if you add the virus into that mix, possibly carried it by an infected bird from the Southern United States, you have the right conditions for amplification of the virus in that cycle and then exposure of people to the infected mosquitoes. ELIZABETH FARNSWORTH: Dr. Cohen add anything if you want, but I really want you to tell us about the detective work involved here. How did you figure out what this was since you had never had it before in New York? DR. NEAL COHEN: Well, it certainly was a case of medical detective work and epidemiology with infectious ease disease. We received a report around August 23 from a physician at a local community hospital of two cases of elderly people who seemed to have a febrile illness and some vague neurological signs. Our epidemiologist and infectious disease surveillance team looked at those cases very carefully. And during the course of that investigation, additional cases appeared in the very same community at that facility, and their index of suspicion that there were a connecting link between these cases became very, very high. And over time, they sent the specimens to a special reference laboratories at the state and at the CDC, and considered the diagnosis of St. Louis Encephalitis, even though there was a lot of cynicism in the public health community because it had never appeared before in New York City. As soon as the diagnosis was confirmed, within a matter of hours, the city launched a very aggressive campaign of spraying of insecticide in the neighborhoods that seemed most impacted by these identification of these cases, and in a matter of days after that, as soon as we received our first confirmation of a case in another borough, which was not at all close to the other cases, we embarked upon a city-wide campaign, which we believe at this point has been very successful because we're gaining evidence that the mosquito population is down by about 90 percent over levels that we thought may have been before the spraying program had begun. ELIZABETH FARNSWORTH: Roger Nasci, what have you learned about what to do in these cases or what should have been done earlier so far? ROGER NASCI: The example of medical detective work that Dr. Cohen was talking about I think is the biggest take-home message that the medical and the public health community needs to bring away from this, is there needs to be a continued effort to maintain the type of capabilities that are required to detect emerging diseases in settings like this and to have the ability to respond to them quickly, like the city's done. ELIZABETH FARNSWORTH: And Dr. Cohen, what lessons have you learned in New York? Do you think, for example, that there should have been spraying regularly in the summer? DR. NEAL COHEN: No, I don't think there's any evidence that that would have been appropriate over the course of a number of years now, we haven't had any public health threats as a result of mosquito infestation. In fact, I think what it tells us is that the public health infrastructure needs to be strong and maintained and that our very gifted and dedicated individuals who really worked 24 hours, seven days a week to unmask this problem are at the core of good epidemiology and, frankly, it makes it possible for a local public health agency like our own to respond very, very quickly to a public health threat. ELIZABETH FARNSWORTH: Dr. Cohen, we heard Susan Dentzer say in the setup that some people are more worried about the spray than anything else, and you already said that you're quite convinced that the sprays are safe. What insecticides are you using, and how do you know they're safe? DR. NEAL COHEN: Well, malathion, which is an organo phosphate, is the aerial spray and there's an experience of over 40 years with it. And the concentrations that are being used to combat the mosquito population in New York is extremely small. In fact, it's much less than is used in common variety garden and insect spray repellants, so that we feel that we have no -- historically any cases that would suggest that this is a public health threat, and that, while there may be some individuals who are particularly sensitive who might have chronic respiratory illnesses or asthma we have encouraged them to stay indoors during the spraying. But the degradation of these sprays and of these compounds is so rapid, in a matter of a few hours, that it's entirely safe for them to walk the streets and even if they got sprayed while they were in the street, we think that it's a very low probability that they would face any adverse health problem. ELIZABETH FARNSWORTH: Roger Nasci, anything to add on that? ROGER NASCI: I agree. The track record of all of the materials that are being used for mosquito control in this situation are approved by the EPA, have labels that precisely define how they're to be applied, and the concentrations and half-life are extremely low. The health risk from the insecticides that are being used to control the mosquitoes is negligible. ELIZABETH FARNSWORTH: All right. Thank you both very much for being with us. ROGER NASCI: You're welcome. DR. NEAL COHEN: You're welcome.