Officials say they collected a sample of mosquitoes in one Montgomery County town that tested positive.
If confirmed, this would be the first known locally acquired case of malaria in the state since 1991.
No one has tested positive for West Nile in Pennsylvania this year. However, officials say it has been detected in mosquitoes in nearly every Pennsylvania county.
Mosquitoes from several areas in Reading and Shillington have tested positive for the virus.
Health officials are warning travelers about an outbreak in southern China of a painful mosquito-borne virus called chikungunya, which is spread by infected mosquitoes, mainly Aedes aegypti.
West Nile virus has been detected near a park in Northeast Philadelphia, the Department of Health announced Friday.