PhD, Charles University, 1960
MS, Comenius University, 1956
Aedes (Stegomyia) aegypti is distributed in the tropical and subtropical regions of the world. It is the main vector of yellow fever and dengue viruses in the domestic and peridomestic habitats in West Africa, Central and South America. Two distinct subspecific populations of Ae. aegypti occur in eastern Africa, namely the forest subspecies Ae. aegypti formosus which occurs in the gallery forests and is primarily zoophilic in its feeding behavior and Ae. aegypti aegypti, which co-habitates with humans in their houses and is anthropophilic. The distinct spatial ecological distribution of the forest and the domestic populations prevents their interbreeding. With my colleagues and students we investigated the ecology, behavior, dispersal and population genetics of Ae. aegypti in Kenya, Tanzania and Uganda. Using the mark-release-recapture technique we were able to trace the dispersal movement of individually marked mosquitoes from house to house. The results indicate that mosquitoes infected with yellow fever or dengue viruses are capable of spreading these viruses throughout the entire village within a period of less than one week. Our investigations led to the genetic control of the domestic population in a Kenyan village of Shauri Moyo by developing strains with chromosome translocations and releasing them into the village population of Ae. aegypti. Interbreeding of the geneticaly altered strain with the local natural Ae. aegypti aegypti village population resulted in hybrid sterility and suppression of the Ae. aegypti village population.
Onchocerciasis - “River blindness” is a chronic debilitating disease which affects large populations of people in Africa and Central America. Large concentrations of people living and working on rubber, coffee and tea plantations are infected with a filarial, thread-like worm Onchocerca volvulus. In western Africa, Liberia, Ivory Coast and Nigeria we investigated the epidemiology of transmission of onchocerciasis by their black fly vectors, Simulium damnosum s.l. In Liberia, active onchocerciasis transmission occurs on the Firestone Rubber Plantation (FRP), and in many native villages. Simulium yahense is the vector there which breeds in the rapids of large and medium size rivers. The prevalence of onchocerciasis on the FRP is over 80% and in villages located near large rivers such as Mano, Lofa, St. Paul, Cestos, Cavalla, and in villages located along medium size rivers it is even higher. An experimental treatment of 20,000 people at the Liberian Agriculture Company in Buchanan, Liberia, with a single dose of ivermectin (200 µg/kg of body weight) kept the treated individuals free of microfilariae (mf ) for almost 6 months. Because ivermectin is a microfilaricidal drug only and does not affect adult worms, one year after treatment the mf density in the skin gradually increases to the pre treatment level, but blindness is prevented. Concurrently with the ivermectin treatment, the fly infection and infectivity was also low, and slowly increased toward the end of one year. In late eighties, immunologists, molecular parasitologists and entomologists were ready to study immunity to infection with infective larvae of O. volvulus, which were needed as an antigen for vaccine development.We developed biotechnology for large scale production of infective (L3) larvae. Such large scale production of L3 antigen requires the availability of people infected with microfilariae, methodology for rearing infected flies in the laboratory, dissection of L3 from infected flies and successful cryopreservation of L3 larvae for storage and transfer in liquid nitrogen from Liberia to the USA where the L3 larvae can be revived even after 10 years of storage in liquid nitrogen. Today the technology we developed for mass production of infective larvae is available to other investigators.
Honors and Awards
- Award of the Slovak Academy of Sciences, Project Leader on Ecology of Parasitic Parasitic Arthropods,1961. - Elected to Sigma Xi, Illinois Chapter, 1967. - Director, Biological Research Institute of America, Baltimore, Maryland, 1974-1979. - Director of Research, Liberian Institute for Biomedical Research, Liberia, 1979-1996. - Elected to the New York Academy of Sciences, 1982. - Smithsonian Institution, National Associate, Elected in 1982. - Nobel American Award, 1979/1980. - Listed with Biography in "Who is Who in the East", 1978-. - Listed with Biography in "Who is Who in America", 1982-. - Listed in "Who is Who in the World", 1983-. -Listed with Biorgaphy in Who is Who in Medicine and Health Care" 1996-. - Listed with a Short Biography in American Men and Women in Science", 1982-. - Listed in Biographical and Pictorial Inclusion in the "Dictionary of International Biography" Cambridge, England, 1979. - Elected to Delta Omega, Alpha Chapter at Johns Hopkins University, 1987.