WHO

Yellow fever situation report

30 June 2016

A yellow fever outbreak was detected in Luanda, Angola late in December 2015. The first cases were confirmed by the National Institute for Communicable Diseases (NICD) in South Africa on 19 January 2016 and by the Institut Pasteur Dakar (IP-D) on 20 January. Subsequently, a rapid increase in the number of cases has been observed.

Summary:

Angola: 3464 suspected cases

In Angola, as of 24 June 2016 a total of 3464 suspected cases have been reported, of which 868 are confirmed. The total number of reported deaths is 353, of which 116 were reported among confirmed cases. Suspected cases have been reported in all 18 provinces and confirmed cases have been reported in 16 provinces and 79 of 125 reporting districts.

Mass vaccination campaigns first began in Luanda and have now expanded to cover most of the other affected parts of Angola. Recently, the campaigns have focused on border areas. Despite extensive vaccination efforts circulation of the virus persists.

Democratic Republic of the Congo: 1307 suspected cases

As of 23 June, in the Democratic Republic of The Congo (DRC), the total number of notified suspected cases is 1307, with 68 confirmed cases and 75 reported deaths. Cases have been reported in 22 health zones in five provinces. Of the 68 confirmed cases, 59 were imported from Angola, two are sylvatic (not related to the outbreak) and seven are autochthonous.

Surveillance efforts have increased and vaccination campaigns in DRC have centred on affected zones in Kinshasa and Kongo Central.

The risk of spread

Two additional countries have reported confirmed yellow fever cases imported from Angola: Kenya (two cases) and People’s Republic of China (11 cases). These cases highlight the risk of international spread through non-immunised travellers.

Seven countries (Brazil, Chad, Colombia, Ghana, Guinea, Peru and Uganda) are currently reporting yellow fever outbreaks or sporadic cases not linked to the Angolan outbreak.

Vaccination

WHO Strategic Advisory Group of Experts (SAGE) on Immunization reviewed existing evidence that demonstrates that using a fifth of a standard vaccine dose would still provide protection against the disease for at least 12 months and possibly longer. This approach, known as fractional dosing, is under consideration as a short-term measure, in the context of a potential vaccine shortage in emergencies.

Risk assessment

The outbreak in Angola remains of high concern due to:

• Persistent local transmission despite the fact that nearly 11 million people have been vaccinated;
• Local transmission has been reported in 12 highly populated provinces including Luanda.
• The continued extension of the outbreak to new provinces and new districts.
• High risk of spread to neighbouring countries. As the borders are porous with substantial cross border social and economic activities, further transmission cannot be excluded. Viraemic travelling patients pose a risk for the establishment of local transmission especially in countries where adequate vectors and susceptible human populations are present;
• Risk of establishment of local transmission in other provinces where no autochthonous cases are reported;
• High index of suspicion of ongoing transmission in hard-to-reach areas like Cabinda;
• Enhanced surveillance is needed and further strengthening of surveillance is underway.