Mosquito blood sucked culex sp. Culex sp. Mosquito can carry germs that can cause Japanese encephalitis (brain inflammation), lymphatic elephant disease, West Nile Fever Disease. West Nile Fever is a disease that can lead to mild disease symptoms that affect the human nervous system to severe brain involvement and death. In 2010, 37 people died in Greece due to this disease transmitted from culex mosquitoes.