Kenya is closing in on the end of its Ebola outbreak, with six of the nine confirmed patients now recovered and 18 days passed without a new case, the health ministry said.

Figures published on 6 November show nine confirmed cases of Ebola disease caused by the Bundibugyo virus, including two deaths. Six patients have recovered and one remains in treatment.

The last confirmed case was recorded on 19 October, and no new infections have been found since. Health officials have traced 135 contacts of the confirmed cases.

One cluster, traced and contained

All of Kenya's cases belong to a single cluster. The first patient had travelled from the Democratic Republic of Congo through Uganda and died on 5 October. Four family members and four health workers were among those infected.

The outbreak has remained limited to that cluster, with no wider spread reported in the country, and the steady fall in active cases has raised hopes that the outbreak is coming to an end.

Ebola disease is a severe illness spread through contact with the bodily fluids of an infected person. Early symptoms include fever, fatigue and muscle pain, followed in some cases by vomiting, diarrhoea and bleeding. Patients are treated with supportive care, including fluids and treatment for other infections, while their immune system fights the virus.

The Bundibugyo virus is one of the species of ebolavirus that cause Ebola disease in people. It was first identified during an outbreak in Bundibugyo district in western Uganda in 2007, and it has caused smaller outbreaks in Uganda and DR Congo since.

The countdown to declaring the outbreak over

Kenya cannot yet declare the outbreak over. Under World Health Organization rules, a 42-day countdown begins only once the final patient has recovered and been discharged, and the outbreak is declared over only if no further cases appear during that period.

The 42-day period covers twice the maximum incubation period of the virus, and it is designed to make sure no hidden chain of transmission remains.

The wider outbreak in DR Congo

The Kenyan cases are linked to a much larger outbreak in the Democratic Republic of Congo, where 10,668 cases and 5,198 deaths had been recorded as of 3 November, a case fatality rate of 48.7 per cent.

There is no licensed vaccine against the Bundibugyo virus, although trials of candidate vaccines are under way. The World Health Organization has been supporting the response in both countries, including contact tracing, testing and care for patients.

Sources: World Health Organization; Mount Kenya Times.