Bacteria in the gut of the Anopheles gambiae mosquito inhibit infection of the insect with Plasmodium falciparum, the parasite that causes malaria in humans, according to researchers at the Johns Hopkins Bloomberg School of Public Health. Scientists with the Bloomberg School's Malaria Research Institute found that removing these bacteria, or microbial flora, with antibiotics made the mosquitoes more susceptible to Plasmodium infection because of a lack of immune stimulation. Their study is published in the May 8, 2009, edition of the journal PLoS Pathogens.

Dengue fever is the most common infectious disease transmitted by mosquitoes – some 100 million people around the world are infected. Researchers at the Hygiene Institute at Heidelberg University Hospital were the first to present a three-dimensional model of the location in the human cell where the virus is reproduced. Their research provides an insight into the exact process of viral replication and serves as a model for other viruses whose replication is still unclear, such as the hepatitis C virus. In addition, it offers new approaches for developing measures to prevent or treat dengue fever. Up to now, neither a vaccine nor a specific antiviral therapy exists.

A recently completed international multi-center clinical trial has found that acyclovir, a drug widely used as a safe and effective treatment to suppress herpes simplex virus-2 (HSV-2), which is the most common cause of genital herpes, does not reduce the risk of HIV transmission when taken by people infected with both HIV and HSV-2.