Factors associated with suspected pertussis outbreak in Rimin Gado, Kano State, Nigeria, 2016

Introduction : pertussis or whooping cough, though vaccine-preventable, has remained a public health threat despite the availability of vaccine. In May 2016, we investigated a pertussis outbreak in Gidan Kanawa and Ungwar Yamma settlements in Kano State, North-West Nigeria to characterize the outbreak and determine its associated factors. Method : we conducted an unmatched case-control study with ratio 1:1. A case was defined as any person Results : a total of 83cases were line listed, 43 (52.5%) were males. Median age of cases was 36 months (range 2 - 108 months) with case fatality rate of 9.7%. The attack rates were 1.92% in Ungwar Yamma and 22.1% in Gidan Kanawa. Among cases, the drop-out rate for pentavalent vaccine was 33.3% while 61 (59.8%) were zero dose for pentavalent vaccine in both settlements. The independent factors associated with pertusis were history of contact with case (Adjusted Odds Ratio, AOR 4.5; 95% CI = 2.2 - 9.5) while history of complete pentavalent vaccination (AOR = 0.3, 95% CI = 0.1 - 0.8) was protective. Laboratory results were inconclusive. Conclusion : the major determinants of the outbreak were history of contact with cases and having zero or no dose of pentavalent vaccine. Cases were managed with antibiotics and supportive treatment. We recommended immediate vaccination of contacts.