Pertussis outbreak investigation in Likimsa-Bokore kebele, Meda Walebu district, Bale zone, Oromia region, Ethiopia, 2019: a descriptive cross-sectional study.

Introduction: pertussis is a major cause of childhood morbidity and mortality. Globally, an estimated 45 millions cases and 400,000 deaths occur every year. Meda Walebu surveillance office reported a pertussis outbreak among the residents of the Liqimsa-Bokore kebele communities. We investigated to describe the magnitude of the pertussis outbreak in Likimsa-Bokore kebele of Meda-Walebu district, Bale Zone, Southeast Ethiopia.

Methods: we conducted a descriptive cross-sectional study in April 2019. We identified pertussis cases recorded on the line list. Suspected cases of pertussis were defined as any resident of Likimsa-Bokore kebele with cough illness and any of the following: paroxysms of coughing, inspiratory whooping, post-tussive vomiting, or apnea. The pentavalent vaccine coverage data were extracted from the Bale zone health management information system department database. Microsoft Excel pivot table and SPSS version 23 software cleaned and analyzed the data.

Results: in three months period, a total of 439 suspected cases of pertussis were reported from Likimsa-Bokore kebele of the Meda-Walebu district. Half of the cases 220(50.1%) have occurred in females and the majority of cases 256 (58.3%) occurred in under five years children. The median age of cases was 4 years ranging from 2 months to 30 years (interquartile range= 4 years). The overall Attack Rate (AR) was 55 per 1000 population with a case fatality rate of 0.7% (3 deaths/439). Children less than five years were the most affected age group with an AR of 198 per 1000 population. The administrative pentavalent vaccine coverage of the district was above 100% during the year 2015-2018.

Conclusion: the overall attack rate of pertussis outbreak was high. Children under five years were the most affected age group irrespective of high administrative coverage of the pentavalent vaccine. Strengthening routine immunization management and intensified surveillance system is required for early detection, investigation, and response activities.