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.
Emergency Committee regarding yellow fever
Following the advice of the Emergency Committee (EC) convened on 19 May 2016, WHO Director-General decided that urban yellow fever outbreaks in Angola and DRC are serious public health events which warrant intensified national action and enhanced international support. The events do not at this time constitute a Public Health Emergency of International Concern (PHEIC).
Statement on the Emergency Committee meeting concerning yellow fever
Angola: 2893 suspected cases
As of 1 June 2016, Angola has reported 2893 suspected cases of yellow fever with 325 deaths. Among those cases, 788 have been laboratory confirmed. Despite extensive vaccination campaigns in several provinces, circulation of the virus persists.
Cunene and Malanje provinces have reported, for the first time since the beginning of the outbreak, 5 autochthonous cases.
Democratic Republic of The Congo: 52 laboratory confirmed cases
On 22 March 2016, the Ministry of Health of DRC confirmed cases of yellow fever in connection with Angola. The government officially declared the yellow fever outbreak on 23 April. As of 1 June, DRC has reported three probable cases and 52 laboratory confirmed cases: 44 of those are imported from Angola, reported in Kongo Central, Kinshasa and Kwango (formerly Bandundu) provinces, two are sylvatic cases in Northern provinces, and two other autochthonous cases in Ndjili (Kinshasa) and in Matadi (Kongo Central). The possibility of locally acquired infection is under investigation for at least four non-classified cases.
Uganda: 68 suspect cases
In Uganda, the Ministry of Health notified yellow fever cases in Masaka district on 9 April 2016. As of 1 June, 68 suspected cases, of which three are probable and seven are laboratory confirmed, have been reported from three districts: Masaka, Rukungiri and Kalangala. According to sequencing results, those clusters are not epidemiologically linked to Angola.
The risk of spread
The virus in Angola and DRC is largely concentrated in main cities; however there is a high risk of spread and local transmission to other provinces in both countries. There is also a high risk of potential spread to bordering countries especially those previously classified as low-risk for yellow fever disease (i.e. Namibia, Zambia) and where the population, travellers and foreign workers are not vaccinated against yellow fever.
Three countries have reported confirmed yellow fever cases imported from Angola: Democratic Republic of The Congo (DRC) (44 cases), Kenya (two cases) and People's Republic of China (11 cases). This highlights the risk of international spread through nonimmunised travellers.
A further three countries have reported suspected cases of yellow fever: Republic of Congo (one case), Sao Tome and Principe (two cases) and Ethiopia (22 cases). Investigations are ongoing to identify the vaccination status of the cases and determine if they are linked with Angola.
The outbreak in Angola remains of high concern due to:
Persistent local transmission in Luanda despite the fact that approximately eight million people have been vaccinated.
Local transmission has been reported in ten highly populated provinces including Luanda. Luanda Norte, Cunene and Malenge are the provinces that most recently reported local yellow fever transmission.
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 crossborder 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.
Inadequate surveillance system capable of identifying new foci or areas of cases emerging.