Abstract
IntroductionDespite 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.MethodsWe 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.ResultsMedian 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-attack-rate was 83/1,786 (4.7%); Age-specific-case-fatality-rate was 21/83 (25.3%); Age-specific-proportional-mortality-ratio was 21/24 (87.5%). A total of 61 (39.4%) zero doses and 30.1% Pentavalent dropouts were documented. Multivariate analysis revealed parental refusal (adjusted OR = 27.8; CI = 8.8-87.7), contact with a case (AOR = 7.9, CI = 4.3-14.7, P = 0.000), belonging to the Muslim faith (AOR = 2.0; CI = 1.1-3.5) and having mothers with informal education only (AOR = 4.7, CI-2.6-8.4) as independent predictors of pertussis infection.ConclusionSub-optimal vaccination due to parental refusal and informal education of mothers were major determinants of pertussis infection. We conducted awareness campaigns of key immunization messages targeted at the informal education sector. We ensured appropriate case management, contact vaccination and health education in public gatherings, worship places and schools.
Highlights
Pertussis, known as whooping cough, is a highly communicable acute respiratory tract disease predominantly affecting children and caused by a gram-negative bacterial species, Bordetella pertussis [1]
Epidemiological data from high-income countries show that, despite high vaccine coverage, the pertussis burden has increased in non-immunized or partially immunized infants [8]. This resurgence of pertussis has most likely arisen through a combination of factors: improved diagnostics, pathogen adaptation which may have reduced the efficacy of pertussis vaccines, waning immunity occurring after vaccination, vaccination which induces short duration of protection compared with natural infection with B. pertussis [9,10,11,12]
A similar observation was made by Preziosi et al in Senegal, 1986 who reported that annual incidences were always higher among girls, but contrary to the report of Michel who reported no gender predilection in the occurrence of pertussis [5, 17]
Summary
Known as whooping cough, is a highly communicable acute respiratory tract disease predominantly affecting children and caused by a gram-negative bacterial species, Bordetella pertussis [1]. The global Diphtheria, Pertussis, Tetanus (DPT) vaccination coverage moved from 5% in 1974 to 83% in 2011, yet, almost one-fifth of the world’s children had not received the DPT series during their first year of life [6]. Most of these unvaccinated children live in developing countries Nigeria with a projected population of 182 million people in 2015 [7]. Epidemiological data from high-income countries show that, despite high vaccine coverage, the pertussis burden has increased in non-immunized or partially immunized infants [8]. This resurgence of pertussis has most likely arisen through a combination of factors: improved diagnostics, pathogen adaptation which may have reduced the efficacy of pertussis vaccines, waning immunity occurring after vaccination, vaccination which induces short duration of protection compared with natural infection with B. pertussis [9,10,11,12]
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