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Neglected Tropical Diseases |
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Recent Scientific Findings
Using Bacteria to Prevent the Transmission of Lymphatic Filariasis Lymphatic filariasis, commonly known as elephantiasis, affects over 120 million people in 80 countries. It is caused by Wuchereria bancrofti, a filarial worm, which is transmitted to humans through the bite of an infected mosquito. Disease control efforts through drug therapy and the use of insecticides has had limited success. Scientists are now looking to the use of novel vector control strategies to provide an additional tool to break the cycle of disease transmission.
Dr. Steven Dobson from the University of Kentucky and his collaborators in Tahiti are studying an innovative approach to vector control. If successful, the target mosquito population will be suppressed to the point where transmission of worms to humans will not occur or will be minimal. Dr. Dobson and his team are studying Aedes polynesiensis mosquitoes infected with the bacteria Wolbachia to suppress the mosquito population in French Polynesia. The bacteria alter the reproductive capabilities of insects they infect, often causing sterility in females. By encouraging Wolbachia infection among mosquito populations, Dr. Dobson’s team hopes to decrease and eventually reduce the population of A. polynesiensis, lowering the number of infected mosquitoes capable of transmitting the disease-causing worm.
Brelsfoard CL, Séchan Y, Dobson SL. Interspecific Hybridization Yields Strategy for South Pacific Filariasis Vector Elimination. PLoS Negl Trop Dis. 2008 Jan 16;2(1):e129.
Understanding How DEET Insecticide WorksDEET (chemical name, N,N-diethyl-meta-toluamide) has been used for over 50 years as an effective insect repellent; however, the mechanisms behind how the insecticide repels insects have not been well understood. Until recently, the hypothesis has been that DEET masks the odors that insects find attractive, such as lactic acid and carbon dioxide, resulting in the insect being unable to find its host.
NIAID-supported researchers, led by Dr. Gregory Lanzaro of the University of California Davis, examined how DEET works on Culex quinquefasciatus mosquitoes. This species of mosquito is a vector of arboviruses and filarial worms, which cause disease in humans. The team found that DEET does not, as previously thought, interfere with attractive odors, but rather, that mosquitoes are able to directly detect DEET which subsequently causes the mosquitoes to avoid any surface where DEET has been applied. Improved knowledge about how DEET repels mosquitoes may result in more effective use of this repellent for improved protection against disease-transmitting insects.
Syed Z and Leal WS. Mosquitoes smell and avoid the insect repellent DEET. Proc Natl Acad Sci. 2008 Sept;105(36):13598-603.
New Metabolic Pathway Discovered in MosquitoesNovel control strategies for mosquitoes are needed for the effective control of the diseases they transmit. One promising approach is through better understanding the unique metabolic pathways of mosquitoes. Such improved understanding may lead to the development of novel control strategies that do not affect non-target organisms, including humans.
NIAID-supported researchers, led by Dr. Roger Miesfeld from the University of Arizona, have discovered a second, previously unknown, metabolic pathway in female Aedes aegypti mosquitoes, the primary vector of dengue. The newly discovered process metabolizes uric acid into urea in a pathway that may provide a target for novel insecticides. This discovery could lead to control efforts that uniquely affect mosquitoes.
Scaraffia PY, Tan G, Isoe J, Wysocki VH, Wells MA, and Miesfeld RL. Discovery of an alternate metabolic pathway for urea synthesis in adult Aedes aegypti mosquitoes. Proceedings of the National Academy of Sciences; 105: 518-523, 2008.
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