Kenya has increased its surveillance for yellow fever disease at the Jomo Kenyatta International Airport, after two cases were confirmed in the country, both originating from Angola.

One of the infected patients died at Nairobi’s Kenyatta National Hospital, the country’s chief referral and teaching institution, while the other is undergoing treatment.

According to the Ministry of Health, laboratory investigations conducted at the Kenya Medical Research Institute (Kemri) on three samples tested positive for Yellow fever antibodies in the two cases, and negative for Ebola and Marburg, which exhibit similar symptoms.

But Eric Osoro, who heads the ministry’s Zoonotic Disease Unit said there was no need to panic as the risk of infection is minimal.

“A 2013 Kemri study across the country established the level of risk of the disease at below one per cent, which is lower than the five per cent that the World Health Organisation classifies as low-risk to the disease,” said Dr Osoro.

There has been a Yellow fever outbreak in Angola since December last year. The country has so far recorded 250 deaths as a result of the viral disease, with some 900 suspected cases turning up at health institutions each day.

Kenya’s Cabinet Secretary in the Health Ministry, Dr Cleopa Mailu, said officials were now screening travellers coming from or on transit through Yellow fever-risk countries.

Dr Osoro said that so far six people had been returned to Angola for lacking the yellow fever vaccination card.

Kenya reported its last yellow fever case in 1990 in the Rift Valley while Uganda and South Sudan did so three years ago.

Yellow fever vaccinations are routinely recommended for travellers to Angola, although the country had not previously witnessed a significant outbreak since 1986.

“In Kenya, only children in the endemic region of Rift Valley are vaccinated at nine months and those travelling to high risk countries,” said Dr Osoro.

There is no specific treatment for the viral disease which is transmitted by infected mosquitoes, and is found in tropical regions of Africa and Latin America’s Amazon basin.

Symptoms include severe headache, nausea, vomiting and fatigue. Many cases are mild, last less than a week and the person makes full recovery, according to WHO. Up to 50 per cent of severely affected people die if left untreated.