ABSTRACT
Tropical disease research was almost wholly concerned with parasitic diseases. Parasitic diseases are those caused by protozoa and helminths. The schools of tropical medicine in the US and Europe focused largely on those organisms. The researchers found out that the greatest killers in the developing world were not the parasitic diseases, but the diarrheal diseases and acute respiratory infections caused largely by bacteria and viruses. The parasitic diseases, however, caused an enormous amount of morbidity due to their prevalence and chronicity. Individuals may not only have one of them, but, in many cases, seven or eight different parasites. The one vaccine in the diarrheal area that looks somewhat hopeful is that for the rotaviruses which cause about 15-20 percent of lethal diarrheal episodes among infants and young children. Molecular biology not only offers remarkable opportunities to produce vaccines, but also key methods for producing new drugs. Most drugs act through protein receptors and enzymes.
