West Nile Virus
The West Nile virus (WNV) is an infectious disease spread mainly through mosquito bites. The virus is most often passed to humans through the bite of an infected Culex mosquito. Mosquitoes become infected by biting infected birds. Occasionally, the virus can spread through blood transfusions, organ transplants or from mother to baby during pregnancy, delivery or breastfeeding. Anyone living in or visiting regions where the virus is found can become infected. All continental U.S. states have reported cases of West Nile. Individuals over age 60 and those with weakened immune systems or chronic illnesses have a higher risk of severe disease.
Zika Virus
Zika virus is spread through the bite of an infected Aedes aegypti or Aedes albopictus mosquito. It can also be spread between sexual partners. A pregnant individual who becomes infected can pass the virus to their fetus, which may lead to birth defects. Zika is most common in tropical and subtropical regions, including parts of Africa, the Americas, Southern Asia and the Western Pacific.