The outbreak of Ebola virus disease in Guinea, Liberia and Sierra Leone is the worst ever, killing more than 700 people this year. Below are frequently asked questions 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 Organisation. Ebola jumps to humans from infected animals including chimpanzees, gorillas and bats that live in the rainforest through contact with blood or other bodily
fluids such as urine and 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 infectious 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: What are the symptoms of the virus?

A: Sudden onset of fever, intense weakness, muscle pain, headache and sore throat are typical signs and symptoms. This is followed by vomiting, diarrhea, rash, impaired kidney and liver function, and in some cases, both internal and external bleeding. Infections can only be confirmed through laboratory testing.

Q: How is this outbreak different from past outbreaks?

A: The current outbreak in Guinea, Sierra Leone and Liberia is the first time Ebola has appeared in West Africa. Until now, the Democratic Republic of Congo and Uganda have seen the biggest outbreaks, which have tended to be in isolated areas in single countries.

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: How long does it take for symptoms to appear?

A: In the past, the incubation period has ranged between 2 and 21 days. In the current outbreak, it has been between 4 and 6 days, according to the WHO.

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 U.S. That’s how the disease spread to Nigeria. Patrick Sawyer, a Liberian
government worker infected with Ebola, took a July 20 flight to Lagos and died five days later.

Q: Is there any treatment or cure for Ebola?

A: There is currently no specific treatment to cure the disease. Severely ill patients require intensive supportive 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. Safety studies in healthy humans may begin in the first half of next year, according to Defyrus. While Tekmira Pharmaceuticals Corp. is also testing its Ebola therapy, the U.S. Food and Drug Administration placed the trial on hold due to safety concerns.