Deteriorating Public Health Infrastructure
Finally, we have seen a deterioration in our public health infrastructure in the past 30 years, decreasing resources, decay in the infrastructure, a shortage of trained personnel, and a total lack of effective vector control for a lot of these diseases. Basically in the past 50 years we have changed our public health approach from preventive medicine to what I call ‘curative medicine.’ This has lead to what I call the "magic bullet syndrome." People do not want to take the responsibility for disease prevention. They prefer to wait until they get sick, and then they expect to be treated and cured. People are not thinking in terms of prevention of these diseases, and a lot of them certainly can be prevented.
Climate Change
In the popular press, you read all about El Niño and global warming, and how these factors influence changes in vector-borne diseases. Vector-borne diseases, mainly malaria, dengue and yellow fever, are most frequently associated with climate change. We really do not know whether climate change has influenced the emergence of any of these diseases. As far as we can tell, there is no evidence that climate change has been responsible for any of the resurgence or emergence that we have seen to date, but certainly in the future it could be. We’re in the process now of trying to get a National Academy of Sciences, Institute of Medicine committee to study the influence of climate change on infectious diseases with emphasis on vector-borne diseases. In a year or two we may have some better idea.
![](index.jpg)
IV. Prospects for the Future
What do we do about this? How are we going to reverse this trend? Are we going to just sit back and wait for it to go on, or do we try to reverse the trend of emergent vector-borne diseases?
Population Growth and Urbanization Control
We have to get a handle on population growth in the world. Most of the population growth in the next 25 years is projected to occur in developing countries, mostly in urban areas. Public health officials do not normally work with waste management officials and city or urban planners. We work in isolation of each other, and we need to get together and start working with the urban planners to gain control of the whole process of urbanization. The place to start is with population control.
Emphasize Prevention—Integrated Prevention Programs
We need to change the way we think in terms of public health. We have got to stop thinking of epidemic and emergence response and start thinking of disease prevention. A lot of diseases can be prevented. We can develop surveillance systems, have early warning predictive capability, and implement strategies to prevent major epidemics. We simply do not do it because our policy makers are afraid to respond to something unless there is a major epidemic occurring. Politically it is very difficult to get support to prevent a disease, but very easy to get support to respond to an epidemic. We need, public outreach and education. We’ll never be able to do this without the help of the people who are creating the problems that we’re dealing with. We desperately need to rebuild our public health infrastructure, not only in this country but also in countries around the world. In terms of vector-borne diseases, personnel and resources are critical. Of all the major emergent resurgent diseases, infectious diseases, vector-borne really are at the bottom of the pile in terms of economic support and personnel.
We need to support research and develop new, integrated prevention strategies including more effective vector control and vaccine research. We need to understand these diseases better to prevent them.
![](index.jpg)
Q&A
[question: I was just curious about the clinical differences between Lyme disease in Europe and China versus in the United States?]
In Europe, Lyme disease has a greater neurologic component, more neurologic disorders associated with it than in the United States where it’s mostly associated with acute arthritis. Some people, however, feel that that distinction is not valid. In the United States a lot of the neurologic disorders associated with Lyme disease are not confirmedIf you have CNS infection, one of the gold standards is to detect antibody in the cerebral spinal fluid. They have been able to do that in Europe at a higher rate than we do the U.S. A lot of people who want to blame Lyme disease for everything. The CDC is trying to support research to try to define what really is Lyme disease infection and what is not. In the southeast and south central part of the United States, where a lot of Lyme-like diseases occur, we have not been able to confirm Borrelia burgdorferi infection. We think that there is a new spirochete that we have detected in that area, and it’s probably associated with another tick vector that is causing some of that disease.
[question: There is not a reliable serological test for Lyme diseases.]
We do not have a really accurate serologic test yet for Lyme disease, but we do have fairly good tests. A lot of the tests are sensitive, but non-specific. They cross-react with everything. We have worked very hard over the past several years to develop the specificity of the IGM and IGG Western Blot test. Through confirmation by isolation of the spirochete we feel that we have a good two-stage test. In the past, a lot of people developed diagnostic tests using sera that were based on a clinical diagnosis. We have not done that with any other infectious agent to my knowledge. We usually develop tests using sera that have been collected from patients that we know are infected with the agent. We have worked hard over the last 5 or 6 years to isolate borrelia burgdorferi from patients, and use those samples to develop tests. So I would disagree that we do not have a good test. It is not the best test yet, but we do have a reasonably accurate test.
AMK: You mentioned the impact of commerce on Aedes albopictus, which presumably was the tire trade. Is that same shipping of microenvironments important to the distribution of Aedes Aegyptus? Are there other solid waste vehicles that you are aware of that are shipped around the world that have created the same kind of transportation for vectors?
Aedes aegypti. does not breed in the tire depots to the extent that Aedes albopictus does. Although in the past, tire depots and water barrels on ships were one of the main mechanisms that Aedes aegypti got transported all over the world. Aedes aegypti is primarily an urban species, highly associated with humans, and it prefers to live in urban deserts. Aedes albopictus, although it occurs in cities of the tropics in Asia, is primarily in the larger gardens and does not go inside the houses quite to the extent. If there is a tire pile there, it’ll be almost 100% Aedes albopictus and not Aedes aegypti. If there is a tire laying in the back yard somewhere, then it will probably have Aedes aegypti in it. If you go into the suburban areas where the tire piles generally are, it’ll have Aedes albopictus and not so much Aedes aegypti. It has been responsible for much of the reinfestation of Latin America.
AMK: Have you studied new construction sites in the same sense of creating vector microenvironments?
Not specifically. We know that that was a major factor in Jedda in 1994, but have not really done any specific sites anywhere else.
[question: In the past, the International Health Regulations have only covered three diseases. They are talking about increasing the scope of reportable diseases to include that variety of syndromes including hemorrhagic fevers. Do you think that is going to result in improved international surveillance or distribution of international information about potentially international outbreak, or do you think people still aren’t going to report?]
There are two issues here: 1) changing from a disease specific to a syndrome type reporting 2) international cooperation and whether the countries will actually abide by the international health regulations. They have totally ignored it for the last 30 years. I do not know why just by changing to a syndrome reporting system that these countries are going to report more. Some people have reservations about this whole approach and how it is going to work. WHO is becoming much more proactive in changing the international health regulations and enforcing them.
[question: How can you maintain a program for a specific disease that is not that important at this time when there are other things that are more pressing? How can you convince people to fund them?]
I have felt that the trends in public health in the past 30 years have been unfortunate. Some diseases have not been dealt with the way they should be and, others are totally ignored. We do not enforce things like the International Health Regulations. From a policy point of view, there is no international cooperation and collaboration.
Readings:
Gubler, D.J. "Epidemic Dengue and Dengue Hemorrhagic Fever: a Global Public Health Problem in the 21st Century". Emerging Infections I, pp. 1-12.
Gubler, D.J. "The global resurgence of arboviral diseases". Transactions of the Royal Society of Tropical Medicine and Hygiene, 1996, (90) 449-451.
Dennis, David T. "Lyme Disease". Dermatoepidemiology, Vol. 13, Number 3, 1995, pp. 527-547 (optional).
Centers for Disease Control.. "Lyme Disease - United States, 1996". Morbidity and Mortality Weekly Report, Vol. 46, Number 23, 1997 (optional).
Return to Title PageHOME | List of Lectures