Stopping parasites before they mutate.

• Position: Infectious Diseases

Infectious disease-fighting drugs could be designed to block a pathogen's entry into cells rather than to kill the bug itself, research at Ohio State University, Columbus, shows. Historically, medications for infectious diseases have been designed to kill the offending pathogen. This new strategy is important because many parasites and bacteria eventually can mutate their way around drugs that target them, resulting in drug resistance.

In this study, scientists show that using an experimental agent to block one type of an enzyme in cell cultures prevents a specific parasite from entering white blood cells, a step required for the parasite to cause infection. This method applies to pathogens that must enter a host cell to survive and do their damage. Some bugs can thrive in a host body outside cell walls.

The researchers tested the experimental drug against Leishmania parasites, which are transmitted by the bite of infected sand flies. The pathogen causes a parasitic skin infection common in tropical and subtropical regions, with an estimated 1,500,000 new cases diagnosed each year worldwide.

"This represents a new way of thinking about...