The outbreak of Ebola is the worst known. About the disease:
Q: How does an Ebola outbreak start and spread?
A: The origin of the virus is unknown, but fruit bats are considered the most likely host, according to the World Health Organization. Ebola jumps to humans from infected animals, including chimpanzees, gorillas and bats, through contact with blood, urine or saliva. Infection can also occur if broken skin or mucous membranes of a healthy person come into contact with environments that have become contaminated with an Ebola patient's fluids, such as soiled clothing, bed linen or used needles.
Q: Can coughing and sneezing spread the virus?
A: While an infected person who sneezes or coughs directly in another person's face could infect that person, Ebola primarily enters the body through tiny cuts or abrasions, or through mucus membranes of the eyes, nose, ears and mouth.
Q: How is this outbreak different from past outbreaks?
A: The current outbreak in Guinea, Sierra Leone and Liberia is the first appearance of Ebola in West Africa. Until now, the Democratic Republic of Congo and Uganda have seen the biggest outbreaks. A lack of border control has allowed infected people who didn't seek medical attention because of fear, suspicion or stigma to travel freely among the three countries.
Q: What are the chances that it will spread beyond Africa?
A: Given the delayed onset of symptoms, infectious disease experts don't rule out the possibility that an infected person who doesn't feel ill would board a plane to Europe or the United States. That's how the disease spread to Nigeria.
Q: Is there a treatment?
A: There is currently no specific treatment to cure the disease. Severely ill patients require intensive care. They are frequently dehydrated and need intravenous fluids or oral rehydration with solutions that contain electrolytes.
Q: Where do we stand with developing drugs for Ebola?
A: An experimental antibody cocktail being developed by the National Microbiology Laboratory in Winnipeg, Canada, the U.S. Army and two drug companies, Mapp Biopharmaceutical Inc. of San Diego and Toronto-based Defyrus Inc., has shown promise in animal tests. Studies in humans may begin in 2015.