Ebola is a serious and often fatal illness caused by a virus. Several viruses can cause Ebola disease in humans, including Ebola virus and Sudan virus. Symptoms of Ebola include fever, headache, muscle pain, weakness, fatigue, diarrhea, vomiting, stomach pain, and severe bleeding and bruising.

More broadly, Ebola virus and Sudan virus are part of the Filoviridae family, which also includes the viruses which cause Marburg disease. There are two known viruses which can cause Marburg in humans and nonhuman primates. Like Ebola, Marburg symptoms can include fever, muscle aches, weakness, diarrhea and vomiting, and severe bleeding. In severe cases, Marburg can be fatal.

Cases of Ebola and Marburg virus disease are rare, but outbreaks occasionally arise in Africa, where the viruses circulate among some populations of animals, such as bats. Humans can acquire ebolaviruses and Marburg viruses from infected animals, or from other people. When spreading between humans, both Ebola and Marburg are transmitted through direct contact with the bodily fluids (such as blood or mucous) of an infected person.

The first vaccine for Ebola virus, rVSV-ZEBOV, which was developed with assistance from NIAID, was approved in the United States in December of 2019. This vaccine and others can now be used to protect people in high-risk areas, or people who have had contact with sick Ebola virus disease patients. However, these vaccines are not designed to provide protection against Ebola disease caused by other viruses, such as Sudan virus. In addition, monoclonal antibody treatments for Ebola can improve patient survival. NIAID is committed to conducting and supporting research on additional treatments, diagnostics, and preventative measures for these diseases.

Zika virus, like other members of the flavivirus family including dengue and West Nile virus, is most typically transmitted to humans through the bite of infected Aedes aegypti mosquitoes. Less commonly, Zika virus can be spread from person to person through sexual intercourse. Most people who become infected with Zika virus do not become sick; but about 1 in 5 people may develop such symptoms as fever, rash, and conjunctivitis (reddened eyes). People who become infected while pregnant may transmit the virus to the fetus, which can result in very serious birth defects, including microcephaly (unusually small head).  

Zika virus was discovered in the Zika forest in Uganda in 1947. In 2015, cases were reported in Brazil and an outbreak of Zika virus disease followed in South and Central America as well as the Caribbean. The first cases of locally transmitted Zika virus in the continental United States were confirmed in Florida in July 2016. No cases of mosquito-transmitted Zika virus have been detected in the United States since 2018. 

NIAID supports research to better understand Zika virus, the disease it causes, and ways to combat it, including research on diagnostics to rapidly determine if someone is or has been infected with Zika and to distinguish from other flaviviruses.