This jump is genetically programed to occur when the fleas get hot. With this knowledge, it may be possible to block the effect in plague bacteria, rendering the microbes unable to infect humans. Alternately, scientists are trying to change the ability of mosquitoes to carry diseases such as malaria and yellow fever. Scientists have been able to insert genes into mosquitoes that disrupt the disease transmission system, but more testing is needed before such genetically altered bugs are sent out into the environment to breed. Meanwhile, innovations in vaccinology, such as the use of microbial DNA to prompt an immune response without transmitting disease, are also just beginning to be explored.
Ease of use is another issue being explored in vaccinology.
For instance, experiments are under way now at the American Military Research Institute on Infectious Diseases, located in Ft. Detrick, Md., on vaccines that can be consumed in normal foodstuffs, rather than injected. This entails genetically engineered fruit and vegetables that would be sold in local markets. But experts say the promise of genetic intervention is overshadowed by the social dilemmas presented by infectious disease.