On 8 April 2016, the National IHR Focal Point of Uganda notified WHO of an outbreak of Yellow Fever (YF) in Masaka district, south of Kampala. An alert concerning a suspected outbreak of viral haemorrhagic fever in Kaloddo village, Masaka district was initially sent on 26 March. A cluster of three cases from a single family was reported after patients presented with high-grade fever, were non-responsive to anti-malarial treatment with haemorrhaging signs and acute neurological signs (convulsions and unconsciousness). From 28 March to 1 April, a rapid response team (RRT) was deployed to carry out investigation and response activities. The RRT confirmed the deaths, activated the district task force, set up a treatment facility in Masaka, and collected and referred samples to the Uganda Virus Research Institute (UVRI) for laboratory testing. In addition, the team used a case definition for haemorrhagic fevers and proceeded to carry out active case search to identify additional suspected cases. On 29 and 30 March, 6 samples were sent to the UVRI and tested negative for all Ebola virus disease, Marburg virus disease, Crimean-Congo haemorrhagic fever, Rift Valley fever by polymerase chain reaction (PCR). On 8 April, Yellow Fever was confirmed on three samples by PCR, two blood samples tested positive for salmonella non-typhi and one tested positive for malaria. On 21 April, at least four samples were re-confirmed positive by PCR at CDC Fort Collins (WHO Collaborative Center for Yellow Fever). From 26 March to 18 April, 30 cumulative suspected cases, including 7 deaths, were reported from Masaka, Rukungiri, Ntungamo, Bukumansimbi, Kalungu, Lyantonde, and Rakai. Of these, 6 cases and 2 deaths were confirmed in Masaka district (5 cases), and Rukungiri district (1 case). The mean age of the cases is 23 years old. The majority of cases are male. The cases do not have any history of travel outside of Uganda.
Public health response
The Ministry of Health of Uganda, with the support of WHO, Centers for Disease Control, Médecins Sans Frontières and other partners are supporting the response to the outbreak. WHO AFRO shared relevant guiding documents with the country for conducting risk assessment, vector control and outbreak management. The district task force which coordinates the response at district level developed a response plan and meets regularly. A multidisciplinary investigation team (physicians, laboratory experts, communication specialists, an epidemiologist and an entomologist) was sent to the affected district to conduct in-depth investigations and provide technical support to the District Task Force. Active surveillance has been enhanced through the activation of the alert desk and provision of alert free lines to the public. Case management, social mobilization, reactive vaccination and a rapid YF risk assessment are ongoing. A YF management centre was established in Masaka and Yellow Fever vaccine has already been requested from the International Coordinating Group on Vaccine Provision for reactive vaccination.
WHO risk assessment
The current outbreak in Uganda is occurring in the context of international export of YF cases from Angola to China, the Democratic Republic of the Congo, and Kenya. Uganda is situated in the “Yellow Fever belt” of Africa and is considered a country at risk of Yellow Fever virus transmission. Last outbreak of Yellow Fever was reported in December 2011. The affected districts are in south-western Uganda close to Democratic Republic of Congo, Rwanda and Tanzania. As the borders are porous with substantial cross border social and economic activities, further transmission cannot be excluded. WHO continues to monitor the epidemiological situation and conduct risk assessment based on the latest available information.
On 22 March 2016, the National IHR Focal Point of the Democratic Republic of Congo (DRC) notified WHO of cases of Yellow Fever (YF) in connection with the outbreak currently occurring in Angola (see DON posted 13 April 2016). From early January to 22 March, a total of 453 suspect cases of YF, including 45 deaths were reported by the national surveillance system. Further investigations identified 41 cases potentially related to the Angola outbreak. These cases were confirmed by laboratory testing at the Institute National of Biomedical Research (INRB) in Kinshasa. Of these 41 cases, 16 have also been confirmed by the regional reference laboratory, Pasteur Institute (IP) in Dakar: 13 of the cases were detected in Kongo Central province (formerly Bas-Congo) and 3 cases reported from Kinshasa. Kongo Central province shares a long, porous border with Angola. Laboratory testing for the other 25 probable cases is pending at IP Dakar. Of these pending cases, two are identified as probable cases of autochthonous transmission – one from Kinshasa, and one from Matadi (in Kongo Central province). Investigations are ongoing and complementary testing at IP Dakar is pending. An investigation team with the support of a virologist from IP Cameroon conducted an outbreak investigation from 7-18 April to assess the presence of local transmission and the risk of amplification. The conducted entomological survey found a high density of Aedes aegypti mosquito larvae, samples of which have also been sent to IP Dakar for infectivity investigation. High entomological density indicates that the risk for amplification of disease is very high. The Government officially declared an outbreak of Yellow Fever on 23 April 2016.
Public health response
The Ministry of Health of DRC has activated the National Committee for outbreak management to respond to this event. Key response activities include:
establishment of coordination mechanisms
social mobilization and community engagement
case management
strengthening surveillance through the training of health workers
dissemination of case definitions
screening and sanitary controls at Points of Entry and screening of refugees’ vaccination status
reactive vector control activities and sensitization of all health facilities (public, private, and traditional practitioners)
vaccination of all individuals travelling to Angola.
Technical support is required to improve the laboratory capacities in terms of diagnosis, especially to avoid delay in laboratory confirmation of cases and improve surveillance. With support from WHO and partners, the country has developed a contingency plan to improve the country's preparedness for a possible response to a larger YF outbreak. The plan is to vaccinate 8 health zones with at least 2 districts in Kinshasa and the six districts of Kongo Central where laboratory confirmed cases were identified (a total of nearly 2 million persons). If local transmission is laboratory confirmed, then other districts would be targeted accordingly.
WHO risk assessment
The situation in DRC is concerning and must be monitored with the highest vigilance. DRC is located in a geographical area known to be YF endemic and autochthonous cases are regularly reported in the whole country. Since January 2016, autochthonous suspected cases have been recorded in the provinces of Bas-Uele, Equateur, Kasai central and Tshuapa. The last outbreaks were reported in Kasai n Oriental in 2013 and in Province Oriental and Katanga in 2014. YF was introduced in the routine EPI in Kinshasa in 2003. According to available data, most of the Capital’s districts (71%) had insufficient YF vaccination coverage (<80%) between 2012-2014. The country, with the support of WHO and partners, needs to implement adequate control measures especially reactive vaccination campaigns in order to avoid geographical spread within the country and to bordering countries. Given the large Angolan community in Kinshasa, the presence and the activity of the vector Aedes spp, the potential establishment of local cycle of transmission in DRC in general and in Kinshasa in particular (the population of Kinshasa Province is estimated at 12.9 million) are of real concern and need to be monitored with extreme attention. The last investigation highlighted the high risk of local transmission; made evident by factors such as high entomologic indices, movement of people between Angola and DRC, and the regular importation of viraemic cases from Angola. The report of Yellow Fever infection in travellers and workers returning from Angola also highlights the risk of international spread of the disease.
WHO advice
There is urgent need to strengthen the Yellow Fever vaccination requirements for travellers in accordance to IHR (2005). Yellow Fever can easily be prevented by immunization provided vaccination is administered at least 10 days before travel. WHO urges Member States especially those where the establishment of a local cycle of transmission is possible (i.e. where the vector Aedes aegypti mosquitoes is present) to ensure that travellers to or from countries with current Yellow Fever transmission are vaccinated against Yellow Fever.
