The WHO chief on Sunday urged Rwanda to keep up its fightback against Marburg, as the country battles an outbreak of one of the world’s deadliest viruses.

There have been 62 confirmed cases and 15 deaths in the outbreak, which was first announced in late September.

No new cases have been detected in the last six days and 44 people have recovered from infection.

Tedros Adhanom Ghebreyesus, the head of the World Health Organization, visited Rwanda to see the outbreak response for himself and hailed the country’s handling of the situation.

“We’re pleased to see that there have been no new cases in the past six days, and we hope that remains the case,” he told a press conference in the capital Kigali.

“But we are dealing with one of the world’s most dangerous viruses, and continued vigilance is essential.

“Enhanced surveillance, contact tracing and infection prevention and control measures must continue at scale until the outbreak is declared over.”

Such a declaration can only be made after 42 days — two consecutive incubation periods — without a new confirmed case.

Marburg is transmitted to humans from fruit bats, and is part of the filovirus family that includes Ebola.

With a fatality rate of up to 88 percent, Marburg’s highly infectious hemorrhagic fever is often accompanied by bleeding and organ failure.

However, the case fatality rate in this outbreak has been held down at 24 percent.

On Saturday, Tedros visited the treatment center where the remaining patients are being looked after.

“Two of the patients we met had experienced all of the symptoms of Marburg, including multiple organ failure, but they were put on life support, they were successfully intubated and extubated, and are now recovering,” he said.

“We believe this is the first time patients with Marburg virus have been extubated in Africa. These patients would have died in previous outbreaks.”

There are currently no officially approved vaccines nor approved antiviral treatments, but potential treatments, including blood products, immune and drug therapies are being evaluated.

A vaccination program using a trial vaccine was launched in Rwanda earlier this month.