Ebola Virus Outbreak in west Africa and its Risk Assessment

The current Ebola Virus outbreak began in Guinea in December 2013. This outbreak now involves transmission in Guinea, Liberia, Nigeria, and Sierra Leone. As of 4 August 2014, countries have reported 1 711 cases (1 070 confirmed, 436 probable, 205 suspect), including 932 deaths. This is currently the largest EVD outbreak ever recorded. And on 8 August 2014, WHO declared the Ebola outbreak in West Africa a Public Health Emergency of International Concern.

Epidemiological facts and experience

• The incubation period of Ebola virus disease (EVD) varies from 2 to 21 days. Person-to-person transmission by means of direct contact with infected persons or their body fluids/secretions is considered the principal mode of transmission. In a household study, secondary transmission took place only if direct physical contact occurred. No transmission was reported without this direct contact. Airborne transmission has not been documented during previous EVD outbreaks.
• There is no risk of transmission during the incubation period and only low risk of transmission in the early phase of symptomatic patients. The risk of infection during transport of persons can be further reduced through use of infection control precautions.
• In the current outbreak, infected travelers have crossed land borders with neighboring countries and there is a possibility that other cases might occur in neighboring countries.
• Historically, several cases of hemorrhagic fever (Ebola, Marburg, Lassa, Crimean Congo hemorrhagic fever) disease were diagnosed after long distance travel but none developed the symptoms during the international travel. Long-distance travelers (e.g. between continents) infected in affected areas could arrive while incubating the disease and develop symptoms compatible with EVD, after arrival.

·         Natural Host of Ebola virus: In Africa, fruit bats, particularly species of the genera: Hypsignathus monstrosus, Epomops franqueti and Myonycteris torquata, are considered possible natural hosts for Ebola virus. As a result, the geographic distribution of Ebola viruses may overlap with the range of the fruit bats.

Risks of Ebola Virus for different groups

Tourists and businessmen/women returning from affected areas in a country

The risk of a tourist or businessman/woman becoming infected with Ebola virus during a visit to the affected areas and developing disease after returning is extremely low, even if the visit included travel to the local areas from which primary cases have been reported. Transmission requires direct contact with blood, secretions, organs or other body fluids of infected living or dead persons or animal, all unlikely exposures for the average traveler. Tourists are in any event advised to avoid all such contacts.

Visiting families and relatives

The risk for travelers visiting friends and relatives in affected countries is similarly low, unless the traveler has direct physical contact with a sick or dead person or animal infected with Ebola virus. In such a case, contact tracing should confirm the exposure and prevent further spread of the disease through monitoring the exposed traveler.

Patients travelling with symptoms and fellow travelers

There is a possibility that a person who had been exposed to Ebola virus and developed symptoms may board a commercial flight, or other mode of transport, without informing the transport company of his status. It is highly likely that such patients would seek immediate medical attention upon arrival, especially if well informed, and then should be isolated to prevent further transmission. Although the risk to fellow travelers in such a situation is very low, contact tracing is recommended in such circumstances.

Risk for health care workers posted in affected areas

There is a risk for healthcare workers and volunteers, especially if involved in caring for EVD patients. However, if the recommended level of precaution for such settings is implemented, transmission of the disease should be prevented. The risk level can be considered very low to low unless these precautions are not followed, e.g. no personal protective equipment, needle stick injury etc.

Template message for travelers and Ebola Virus Disease

• Ebola Virus Disease is formerly Known as Ebola hemorrhagic Fever and  highly fatal up to 90%
• The virus took its name as it is thought to be seen near by Ebola River at first on 1976.
• Infection is by contact with blood or body fluids of an infected person or an animal infected or by contact with contaminated objects.
• Symptoms include fever, weakness, muscle pain, headache and sore throat. This is followed by vomiting, diarrhoea, rash, and in some cases, bleeding.
• Cases of Ebola have recently been confirmed in XXX and YYY.
• Persons who come into direct contact with body fluids of an infected person or animal are at risk.
• There is no licensed vaccine.
• Practice careful hygiene i.e. frequent hand washing.
• Avoid all contact with blood and body fluids of infected people or animals.
• Do not handle items that may have come in contact with an infected person’s blood or body fluids.
• If you stayed in the areas where Ebola cases have been recently reported seek medical attention if you feel sick (fever, headache, achiness, sore throat, diarrhoea, vomiting, stomach pain, rash, or red eyes). 

Ref: www.who.int, Accessed on 9 August 2014