Cholera Epidemic in South Sudan and Uganda and Need for International Collaboration in Cholera Control

Combining the official cholera line list data and outbreak investigation reports from the ministries of health in Uganda and South Sudan with molecular analysis of Vibrio cholerae strains revealed the interrelatedness of the epidemics in both countries in 2014.These results highlight the need for collaboration to control cross-border outbreaks.M ost countries in sub-Saharan Africa are affected by cholera epidemics ranging from annually to every 3-5 years or more (1,2).Cholera tends to be reported at the national or subnational level with few attempts to understand how it may simultaneously affect multiple countries in the same region (3-5).Published studies combining both microbiological and epidemiologic evidence are also scarce.However, better understanding of the interrelatedness of cholera spread between neighboring countries can provide the impetus for more cross-border collaboration in the fight against the disease.This subject is especially relevant in areas with porous borders that experience large population movements, like the border of South Sudan and Uganda.Large urban communities or cities in cholera-prone areas may play a role in the persistence and transmission of cholera within Africa, given the high volume of travel between cities and other areas and the relatively high population density.Epidemiologic data do show support for the notion that large cities in Africa are hubs of transmission ( 6), but in-depth analyses are needed to substantiate or refute these hypotheses.Here we explore epidemiologic and microbiological data from cholera epidemics in Uganda and South Sudan in 2014 to establish possible interrelatedness. The StudyWe used the official cholera dataset and outbreak investigation reports from the ministries of health in Uganda and South Sudan.Both countries use the Integrated Disease Surveillance and Response System (https://www.cdc.gov/globalhealth/healthprotection/idsr/about.html) and have adopted similar case definitions from the World Health Organization for areas with confirmed transmission.A suspected cholera case was defined as acute watery diarrhea in a person >2 years of age.A confirmed case was defined as a suspected case in which a stool sample had a culturepositive result for Vibrio cholerae O1 or O139.Cholera case reporting began on April 25, 2014, in Moyo District in northern Uganda, bordering with Kajo-Keji County in South Sudan (Figure 1, panel A).This region reported 88 cases and 3 deaths in the subsequent weeks (Figure 2).The epidemic was contained after rapid implementation of control measures.Cholera case reporting began on April 29, 2014, in Juba, South Sudan (300 km from Moyo town, Uganda), with a case investigation finding no evidence of travel outside of Juba.Within days, the first reported cholera outbreak in South Sudan since 2009 began, resulting in 6,269 suspected cases, including 105 deaths in health facilities and 51 community deaths (case-fatality ratio 2.4%) by the end of October 2014 (7).Transmission continued in Juba throughout the epidemic, and outbreaks occurred throughout the country, including large outbreaks in the north.In early July 2014, months after the last confirmed case in Uganda but during a period of intense transmission in South Sudan, a new outbreak was reported in Moyo district, in subcounties (Metu and Dufile) that were not Cholera Epidemic in South Sudan and Uganda and Need for International Collaboration in Cholera Control