Angola - Study in cholera hotspots in Angola: Review and propositions for actions to prevent cholera in the most affected areas (October 2018)

Cholera continues to represent a major public health concern in Angola. To guide cholera control and prevention strategies, the current assignment aims to better understand the cholera dynamics in Angola and identify cholera hotspots.

Angola is recovering from a 40-year war that resulted in significant social and economic disruptions, including limited access to potable water and adequate health and sanitation infrastructures, which has rendered the country vulnerable to epidemic-prone diseases such as cholera. Following an unexplained near ten-year lull in cholera outbreaks from 1997 to 2006, Angola experienced a large-scale cholera epidemic that started in the sprawling slums (musseques) of Luanda in early 2006 (67,257 suspected cases). Since 2006, cholera outbreaks have been reported nearly every year in the country (with the exception of 2015), albeit at gradually dwindling rates. 

Over the course of the study, the regularly affected communities were located in northern provinces bordering the DRC, especially Uíge and Zaire, as well as certain provinces in the southwest, such as Cunene, Huíla, Benguela and Namibe. In this study, 11 provinces in Angola were identified as cholera hotspots. The northern province of Uíge was defined as a highest-priority Type 1 hotspot. The southwestern provinces of Benguela, Cunene and Huíla as well as the northwest province of Zaire were defined as high-priority Type 2 hotspots. Luanda Province was defined as a medium-priority Type 3 hotspot. The northern provinces of Cabinda, Lunda Norte, Malanje, and Kwanza Norte and the southern province of Namibe were defined as Type 4 hotspots. Overall, the Type 1 – 4 cholera hotspots accounted for 90.6% of the disease burden throughout the study period. Five provinces affected by outbreaks of extended duration (Type 1 and Type 2 hotspots) reported 39.4% of the total number of suspected cases.

Cholera risk factors leading to the 2006 outbreak in Luanda included severe disruptions in basic health and sanitation services, limited access to potable water, and rapid urbanization due to population displacement. Other cholera risk factors throughout the country included limited access to potable water and sanitation facilities. In 2015, 23% of rural populations and 63% of urban population had access to at least basic drinking water sources. Furthermore, 21% of rural populations and 62% of urban populations had access to at least basic sanitation. As a result, open defecation is also widespread, especially among rural populations (56% in 2015). Extended drought followed by onset of the rainy season likely played a role in the 2013 outbreak in the southern provinces (e.g., Cunene and Huíla). Due to widespread open defecation, heavy rains triggered contamination of the few drinking water sources with fecal matter.

Cross-border cholera transmission from the Democratic Republic of the Congo (DRC) likely played a major role in cholera dynamics in Angola. The two most recent epidemic episodes in Angola (2011-2013 and 2016-2018), occurred in parallel to cholera outbreaks in western DRC. Furthermore, the recent outbreaks in Zaire, Cabinda and Uíge have been epidemiologically linked to cholera outbreaks in western DRC.

Based on the study findings, long-term WASH investments in the Type 1 and Type 2 hotspots are recommended.