Plasmodium vivax
Plasmodium vivax is a protozoal parasite and a human pathogen. This parasite is the most frequent and widely distributed cause of recurring (Benign tertian) malaria, "P. vivax" is one of the five species of malaria parasites that commonly infect humans. Although it is less virulent than "Plasmodium falciparum", the deadliest of the five human malaria parasites, "P. vivax" malaria infections can lead to severe disease and death, often due to splenomegaly (a pathologically enlarged spleen). "P. vivax" is carried by the female "Anopheles" mosquito; the males do not bite.
Saint Louis encephalitis
The majority of infections result in mild illness, including fever and headache. When infection is more severe the person may experience headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, occasional convulsions and spastic paralysis. Fatality ranges from . Aged people are more likely to have a fatal infection.
Mosquitoes, primarily from the genus "Culex", become infected by feeding on birds infected with the Saint Louis encephalitis virus. Infected mosquitoes then transmit the Saint Louis encephalitis virus to humans and animals during the feeding process. The Saint Louis encephalitis virus grows both in the infected mosquito and the infected bird, but does not make either one sick. Only infected mosquitoes can transmit Saint Louis encephalitis virus. Once a human has been infected with the virus it is not transmissible from that individual to other humans.