Yellow fever situation report
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: 3748 suspected cases
In Angola, as of 21 July 2016 a total of 3748 suspected cases have been reported, of which 879 are confirmed. The total number of reported deaths is 364, of which 119 were reported among confirmed cases. Suspected cases have been reported in all 18 provinces and confirmed cases have been reported in 16 of 18 provinces and 80 of 125 reporting districts.
Mass reactive 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. All districts continued with house to house immunization campaigns and routine vaccination.
Democratic Republic of the Congo: 1907 suspected cases
According to the latest confirmed information, DRC has reported 1907 suspected cases (as of 20 July) and 68 confirmed cases (as of 24 June) including 95 reported deaths (Table 1). Cases have been reported in 22 health zones in five of 26 provinces. Of the 68 confirmed cases, 59 were imported from Angola, two are sylvatic (not related to the outbreak) and seven are autochthonous.
The recent technical difficulties at the national laboratory in the Democratic Republic of The Congo (DRC) have been resolved and the laboratory confirmation of yellow fever cases in DRC has resumed. According to the preliminary results of tests performed on a backlog samples, seven new patients have tested positive for yellow fever. Additional investigations to determine the definitive status of these cases are ongoing. Until these investigations are completed, the official case count in DRC remains unchanged.
In DRC, surveillance efforts have increased and vaccination campaigns have centred on affected health zones in Kinshasa and Kongo Central and Kwango. Reactive vaccination campaigns started on 20 July in Kisenso health zone in Kinshasa province and in Kahemba, Kajiji and Kisandji health zones in Kwango province.
The risk of spread
Seven countries (Brazil, Chad, Colombia, Ghana, Guinea, Peru and Uganda) have reported yellow fever outbreaks or sporadic cases not linked to the Angolan outbreak.
An Emergency Committee (EC) was convened on 19 May 2016. The WHO Director-General accepted the EC’s assessment that the urban yellow fever outbreaks in Angola and DRC are serious public health events which warrant intensified national action and enhanced international support. The situation does not currently constitute a Public Health Emergency of International Concern.
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, will be implemented in a pre-emptive mass vaccination campaign in DRC in Kinshasa.
Risk assessment
The outbreak in Angola is receding and no confirmed case has been reported in the country during July (as of 21 July). The confirmed case with the most recent date of symptom onset, 23 June, was reported in Cuanhama district in Cunene province. However, a high level of vigilance needs to be maintained throughout the country.
In DRC, the situation remains concerning as the outbreak has spread to three provinces. Given the presence and activity of the vector Aedes in the country, the outbreak might extend to other provinces, in particular Kasai, Kasai Central and Lualaba.
Transmission of yellow fever in Angola and DRC is mainly concentrated in cities; however, there is a high risk of spread and local transmission to other provinces in both countries. In addition, the risk of potential spread to bordering countries, especially those classified as low-risk (i.e. Namibia, Zambia) and where the population, travelers and foreign workers are not vaccinated for yellow fever.
