Despite the outbreak of Ebola virus disease in West Africa continued to evolve, the World Health Organization (WHO) on Tuesday said in a statement that the disease-affected Nigeria and Guinea have showed some encouraging signs to contain the outbreak.

WHO said the situation in Lagos, Nigeria, where the first imported case was detected in July, looks reassuring. At present, the city's 12 confirmed cases are all part of a single chain of transmission. Those infected by the initial case include medical staff involved in his treatment, a patient in the same hospital, and a protocol officer in very close contact with the patient.

The initial patient, from Liberia, who arrived in Lagos on July 20 and died on July 25, was vomiting frequently during travel and upon arrival. However, no one on the same flight was infected.

WHO noted so far intensive contact tracing has not identified any further confirmed cases outside the initial transmission chain.

In Guinea, where the virus made its first appearance in West Africa last December, WHO added the situation is less alarming than in Liberia and Sierra Leone.

It said public awareness of the facts about Ebola is higher there than in the other affected countries and innovative solutions are also being taken.

For example, respected community leaders have been used to secure the cooperation of 26 villages that were highly resistant to outside help, which contributed to a surge of previously concealed cases were detected.

However, WHO warned the outbreak in Guinea is not under control. As recent experience shows, progress is fragile, with a real risk that the outbreak could experience another flare-up. A case in a previously unaffected area was reported last week, indicating continuing spread to new areas.

As of August 16, the cumulative number of cases attributed to Ebola virus disease in Guinea, Liberia, Nigeria, and Sierra Leone stands at 2,240, including 1,229 deaths. At present, no cases have been confirmed anywhere else in the world outside these four countries.

(Xinhua News Agency August 19, 2014)