Outbreak of suspected pertussis in Kaltungo, Gombe state, Northern Nigeria, 2015: the role of sub-optimum routine immunization coverage

Abstract

Introduction: despite the availability of vaccines, pertussis outbreaks still occur in developing countries. In December 2015 we investigated a pertussis outbreak in Kaltungo, Nigeria to identify determinants of infection and institute control measures.Methods: we enrolled 155 cases and 310 unmatched controls. We defined cases as residents of Kaltungo with paroxysmal or whooping cough lasting 2 weeks with or without vomiting and randomly selected neighborhood controls. Using structured questionnaire, we collected data on socio-demographics, clinical and risk factors. We collected twelve nasopharyngeal swabs for laboratory analysis using Polymerase Chain Reaction.Results: median age was 24 months (range 1-132 months) for cases and 27 months (range 1-189 months) for controls. Female cases and controls were 86 (55.5%) and 150 (48.4%) respectively. A total of 83 (56.6%) cases were in age group 12-59 months. Age-specific-attackrate was 83/1,786 (4.7%); Age-specific-case-fatality-rate was 21/83 This article is published as part of the supplement "Sharing experiences from the field: updates from the Nigeria Field Epidemiology and Laboratory Training Program" sponsored by Nigeria Field Epidemiology and Laboratory Training Program

An epidemiological investigation of the 2019 suspected pertussis outbreak in northwestern Nigeria

“…Regarding the overall case fatality rate, our study found a much lower case fatality rate than the previous studies conducted in Gombe State, Northeastern Nigeria, and Ethiopia. 12 , 13 , 15 However, our study finding is comparable to a study published in 2009 from Argentina where case fatality rate was 0.17% based on analyzed outbreaks data. 19 Furthermore, we found a sex difference in case fatality rate, suggesting that males are more likely to die of pertussis when infected than females.…”

“… 12 , 13 , 18 The survey conducted in Gombe State, Nigeria, also found a higher incidence of pertussis among females. 15 Our study reported an overall higher attack rate of 2.1% compared to previous studies conducted in Ethiopia and northeastern Nigeria. The relatively higher attack rate may be related to the immunization uptake and coverage at household and community levels in Kebbi State and northwestern Nigeria.…”

“…The vaccination uptake among cases in our study is much lower than reported vaccination status in studies from Gombe State, Nigeria, where 42% of the cases received the third pentavalent vaccine. 15 This study from Ethiopia by Almaw et al 13 2017 also reported 51% uptake among cases for the three doses of the pentavalent vaccine. The common denominator in all these studies is the sub-optimal RI against pertussis, which explained the occurrence of outbreaks in the study settings.…”

“…However, our result was somewhat like the Gombe study in the northeastern part of Nigeria, where 2% of the case had cyanosis. 15 The apparent difference in finding between the Nigerian studies and that of Ethiopia may be explained by a varying capacity to elicit the sign due to skin pigmentation and the health workers’ observational skills.…”

“…Our study finding was similar to the report from Kaltungo, Gombe State in the northeastern part of Nigeria, where the most affected age group was 1–4 years. 15 Kebbi State has a persistently low immunization uptake and coverage evident by survey data, 11 , 16 , 17 and this could explain the recurrent outbreak of pertussis. The 2019 administrative coverage for the third dose of pentavalent vaccine in the two LGAs was more than 90%.…”