Professor Laura Harrington is an associate professor in the Department of Entomology here at Cornell University. She studies medical entomology, with an emphasis on mosquito biology and vector-borne disease ecology. Her time spent overseas in countries that are hotspots of tropical diseases has contributed to her unique perspective on academic research, which blends social aspects with science. Dr. Harrington is particularly well versed in the spread and infection patterns of malaria. The Salubrion spoke with Professor Harrington about malaria, the state of malaria research, and the prospects for new diseases in a warmer global climate.
The Salubrion: Your work delves broadly into biology and ecology but also touches aspects of social medicine and public health. What inspired you to pursue this sort of a multi-faceted research career?
Laura Harrington: I am fascinated by the complexity of multi-component systems. The interactions between parasite and pathogens, mosquito vectors, and human hosts are especially complex and interesting to me. The topic is difficult, challenging, and incredibly rewarding to study.
The Salubrion: A “cure” for malaria is like a scientific holy grail. How close are we today to such a “cure” and based on our understanding of the infection, is it more likely to take the form of a pill or a vaccine?
LH: Although scientists have been “close” to finding a “cure” for malaria for decades, the parasite has been able to thwart every effort (by developing resistance to anti-malarial drugs and possessing a large variety of complex target proteins that make vaccine development nearly impossible). An effective vaccine would be the key, but most malaria vaccines developed to date have had a very low success rates. Sadly, we may not see a cure for malaria in our lifetime.
The Salubrion: Many people argue that it doesn’t make economic sense for a pharmaceutical company to invest in malaria research because, frankly, the company is likely never to recoup the cost of development since the medicine will most likely have to be distributed for free. Do you “buy” this line of thinking? Why or why not?
LH: It makes sense. Companies must make money and many people who are experiencing the greatest impact of malaria – who would be the “consumers” of a new drug – have to survive on less than $1.00 USD per day. They simply cannot afford malaria drugs. This issue is further confounded by the problem that it isn’t healthy to continually medicate people living in malaria endemic regions. Some companies have discovered creative ways to make an impact with their products in resource poor countries. For example, Merck has used profits from its popular dog heartworm products sold to pet owners in the US to fund River Blindness control programs in Africa. I can envision a similar model for anti-malarials, where profits from wealthy tourists fund programs in endemic regions.
The Salubrion: To what extent can a purely epidemiological approach to the malaria epidemic be successful (for example, prophylaxis or bed nets distributed to certain specific hot spots in and around mosquito breeding areas)? In your opinion, are these just near-term solutions to a problem that demands a long-term solution?
LH: An epidemiological approach would include several interventions aimed at interrupting the cycle of transmission. Mosquitoes are at the heart of the transmission cycle and, consequently vector control is important. Bednets are effective, but they need to be used in conjunction with other approaches, such as mosquito vector control and drug programs for young children and pregnant women. Education programs for the proper use of bednets are also important and often overlooked. A long term solution for malaria prevention and control must be designed to be sustainable. This has been difficult because malaria control costs money. There just isn’t enough to keep programs going, no matter how much Bill and Melinda Gates and other benefactors pump into the region.
The Salubrion: I understand that you’re not opposed to the use of insecticides (including DDT) as a means of managing the spread of malaria. Naturally, this is a very controversial position. Please elaborate on why it is a reasonable approach to mitigating a worldwide malaria epidemic.
LH: When used appropriately (for example, as surface sprays on indoor walls), DDT can actually save a significant number of lives. This compound alone was responsible for the near eradication of malaria from South, Central America and the Caribbean in the 1960s. Many people don’t realize that DDT has a low human toxicity profile, long residual time, and is very cheap. Many countries already have large stockpiles of it. The concern, of course, is if DDT is improperly used. There is no way to keep farmers from spraying it on their crops in addition to spraying their homes. Once indiscriminate use of DDT happens, other animals such as birds are at risk. Indirect effects are hard to predict and plan for. In some cases, local predators, such as cats, may die from DDT exposure causing increases in rodent populations and loss of harvest. Although the evidence for other impacts of DDT is weak, it is still a concern among scientists.
The Salubrion: The idea that global warming could introduce and/or bring back diseases to areas that previously never had them is very intriguing. Are there signs today that this is happening?
LH: Temperature increases cause changes in seasonality and allow mosquito vectors to expand their ranges. We are currently monitoring the expansion of an invasive species, the Asian Tiger mosquito, into New York State. Whether these range expansions will lead to major outbreaks in the future is still unclear. There is no strong scientific evidence to date that temperature increases alone will lead to increases in vector borne diseases impacting human health. Together, with my colleagues here at Cornell, we are beginning a new project to address this critical issue.
