Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. An estimated 3-5 million cases and over 100,000 deaths occur each year around the world. The infection is often mild or without symptoms, but can sometimes be severe. Approximately one in 10 (5 to 10 percent) infected persons will have severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these people, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.

Why Is the Study of Cholera a Priority for NIAID?

Because the bacteria that cause cholera, Vibrio cholerae, are spread through contaminated water, cholera is not a public health issue in countries where drinking water and sewage are separated and treated. It is unlikely that a large outbreak of cholera would occur in the United States or other developed countries, but cholera epidemics are a very big public health concern in Haiti, India, and other developing areas of the world.

How Is NIAID Addressing This Critical Topic?

NIAID-supported scientists conducting basic cholera research are studying the evolution and genetics of V. cholerae, and how the micro-organism interacts with environmental factors. Scientists are exploring several approaches to develop improved vaccines for cholera, and are devising new drugs based on small molecules and natural products to treat cholera and other related diarrheal diseases.

Pertussis, also known as whooping cough, is a highly contagious respiratory disease. It is caused by the bacterium Bordetella pertussis. Pertussis is known for uncontrollable, violent coughing that often makes it hard to breathe. After fits of many coughs, someone with pertussis often needs to take deep breaths, which result in a “whooping” sound.

Why Is the Study of Pertussis (Whooping Cough) a Priority for NIAID?

Pertussis most commonly affects infants and young children and can be fatal, especially in babies less than 1 year of age. With the resurgence in pertussis in recent years—in 2012, U.S. rates reached a 50-year high of 48,000 reported cases—there remains a strong need for research to support the development of new and effective prevention measures.

How Is NIAID Addressing This Critical Topic?

Over the years, and continuing into today, NIAID has played a key role in developing and implementing the pertussis research agenda, particularly in understanding the infection process and evaluating vaccines and vaccine regimens. 

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.