Evidence Generation for Effective Cholera Outbreak Interventions in Kathmandu Valley, Nepal

cholera;vaccine;integrated control;genetic characterization;spatial epidemiology;Epidemiology

Roskosky, MellisaNelson, Kenrad ;

Johns Hopkins University

关键词: cholera;    vaccine;    integrated control;    genetic characterization;    spatial epidemiology;    Epidemiology;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/60961/ROSKOSKY-DISSERTATION-2018.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

ObjectivesCholera is endemic in 69 countries and is responsible for at least 95,000 annual deaths, over 900 of which are in Nepal. Studies demonstrate a higher risk of cholera in the vicinity of a case. A Comprehensive Targeted Intervention (CTI) was designed and deployed adjacent to cholera cases in the Kathmandu Valley with the intent to reduce rates among neighbors. This dissertation aims to determine if an immediate, integrated response is possible in the Kathmandu Valley while simultaneously generating data to support evidence-based interventions to control cholera in the country.MethodsCholera cases were reported from 15 sentinel site hospitals. A single case initiated the CTI. Bacterial culture was used for confirmation. The strategy included case investigation, water testing, WASH intervention, and health education. Stool samples were collected on filter paper for testing genetic relatedness. Case household location data was analyzed to determine if a reactive, ring vaccination strategy would have been useful in preventing cholera transmission during the outbreak.ResultsBetween June 1 and December 30, 2016, 169 cases of V. cholerae were confirmed by bacterial culture. On average, the CTI Rapid Response Team (RRT) was able to visit the household 2 days after the culture result was received. PCR testing confirmed an additional 24 cases, and MLVA revealed that all samples were members of a single clonal complex. GPS data was available for 69 households and significant clustering of cases was seen over space and time. Approximately 85% of cases within a cluster occurred more than seven days after the index case.ConclusionRRTs were able to visit case households within 48 hours of confirmation and were successful in raising awareness among key stakeholders. The minimal genetic diversity in the clinical samples combined with the shape of the epidemic curve indicated a clonal outbreak consistent with a common source followed by secondary fecal-oral spread. Thus, it seems unlikely that there were multiple introductions of V. cholerae into the Kathmandu Valley in 2016. Clustering suggests an opportunity to prevent cholera cases though ring vaccination. This analysis has provided useful evidence for implementing future cholera outbreak interventions in Nepal.