GENEVA/LONDON (Reuters) - The World Health Organization said on Thursday it was still trying to slow the rate of new infections but had “reasonable confidence” that the Ebola virus plaguing three West African countries had not spread into neighboring states.

Volunteers who will be sent to Africa in the forthcoming days are taught how to work with patients infected with the Ebola virus during a training session at AP-HP hospital Henri Mondor in Creteil, a suburb of Paris October 22, 2014. REUTERS/Philippe Wojazer

Asked whether countries such as Guinea Bissau, Mali and Ivory Coast might have cases of the disease crossing their borders without knowing about or reporting them, WHO assistant director general Keiji Fukuda said he considered that unlikely.

“I think that there is reasonable confidence right now that we are not seeing widespread transmission of Ebola into the neighboring countries,” Fukuda told a news briefing in Geneva.

“It remains a big concern for everybody, but we think that right now we are not seeing it. We think it would be very difficult to miss, basically.”

He conceded that some Ebola cases could go undetected or unreported by authorities “for a few days for a week or two”.

“But if you’re really having outbreaks in which lots of people are dying, given the extensive coverage in all the countries, it doesn’t matter what country that you are in, you simply would not be able to cover up having lots of people die for mysterious reasons.”

Last week, the WHO said it would send teams of experts to Mali and Ivory Coast to check their preparedness.

The economic damage of a major outbreak in Ivory Coast would be felt around the world, since it and next-door Ghana produce about 60 percent of the world’s cocoa beans.

Although Senegal and Nigeria managed to contain the disease imported by travelers, Ebola is still raging in the three countries at the heart of the epidemic.

The WHO’s Emergency Committee advising on Ebola said screening people leaving Liberia, Sierra Leone and Guinea by air, land and sea remained critical for reducing its spread.

SCREENING IMPACT

At a minimum, exit screening should consist of “a questionnaire, a temperature measurement and, if fever is discovered, an assessment of the risk that the fever is caused by Ebola”, the independent experts said after closed-door talks.

“It is important to realize that exit screening is not going to stop everything. It is important to reinforce the message of the importance of the questionnaire, it has to be done in a good way,” said Isabelle Nuttall of WHO’s health security cluster.

To date, 36,000 people leaving Guinea, Liberia and Sierra Leone have been screened and 100 were “deferred from traveling”, she said in response to a query on the latest data.

None had Ebola, spokesman Tarik Jasarevic said by email.

The committee reiterated that there should be no general ban on international travel or trade due to the Ebola epidemic.On entry screening of passengers, introduced by some states, the experts said they could have a “limited effect” when added to exit checks. But the advantages and disadvantages should be weighed carefully and decisions made on a case-by-case basis.

At least 4,877 people are known to have died, but the true toll may be three times as much.

The response to the disease is now based on a “70-70-60 plan” to get 70 percent of patients in isolation and 70 percent of bodies buries safely within a 60-day period ending on Dec. 1.

But the elements needed to achieve that - bed spaces, treatment centers, laboratories, dead-body-management teams and volunteers - are still far short of what is required.

Fukuda, asked when he expected the rate of new infections to slow down, said: “It’s clear that it remains quite a challenge right now, we see the numbers still going up. We still see an extensive effort trying to catch up to that curve and then get beyond the curve.”

The WHO originally appealed for 12,000 local staff and 750 foreign experts, but it has raised those targets to 20,000 and 1,000 respectively. Fukuda said there were only 600 foreign experts so far.