Measles outbreak propagated by children congregating at water collection points in Mayuge District, eastern Uganda, July – October, 2016

Abstract

BackgroundOn 12 October, 2016 a measles outbreak was reported in Mayuge District, eastern Uganda. We investigated the outbreak to determine its scope, identify risk factors for transmission, evaluate vaccination coverage and vaccine effectiveness, and recommend evidence-based control measures.MethodsWe defined a probable case as onset of fever (≥3 days) and generalized rash, plus ≥1 of the following: conjunctivitis, cough, and/or runny nose in a Mayuge District resident. A confirmed case was a probable case with measles-specific IgM (+) not explained by vaccination. We reviewed medical records and conducted active community case-finding. In a case-control investigation involving probable case-persons and controls matched by age and village, we evaluated risk factors for transmission for both cases and controls during the case-person’s likely exposure period (i.e., 7–21 days prior to rash onset). We estimated vaccine effectiveness (VE) using the formula: VE ≈ (1-ORprotective) × 100. We calculated vaccination coverage using the percentage of controls vaccinated.ResultsWe identified 62 probable case-persons (attack rate [AR] = 4.0/10,000), including 3 confirmed. Of all age groups, children < 5 years were the most affected (AR = 14/10,000). The epidemic curve showed a propagated outbreak. Thirty-two percent (13/41) of case-persons and 13% (21/161) of control-persons visited water-collection sites (by themselves or with parents) during the case-persons’ likely exposure period (ORM-H = 5.0; 95% CI = 1.5–17). Among children aged 9–59 months, the effectiveness of the single-dose measles vaccine was 75% (95% CI = 25–92); vaccination coverage was 68% (95% CI = 61–76).ConclusionsLow vaccine effectiveness, inadequate vaccination coverage and congregation at water collection points facilitated measles transmission in this outbreak. We recommended increasing measles vaccination coverage and restriction of children with signs and symptoms of measles from accessing public gatherings.Electronic supplementary materialThe online version of this article (10.1186/s12879-018-3304-5) contains supplementary material, which is available to authorized users.

Measles outbreak investigation in Ginnir district of Bale zone, Oromia region, Southeast Ethiopia, May 2019

“…This is in line with the finding of case control study conducted in Kabridehar town and Kabridehar district of Somali Regional State, Ethiopia, indicating that being vaccinated against measle vaccine is protective factor for contracting measle [ 15 ), 16 ]. Similarly, our finding is consistent with the case control study conducted in Uganda and China indicating unvaccinated against measles was responsible for most measles infection in children [ 18 ), 19 ]. This is due to the fact that vaccination against measles is vital for prevention of measles infection [ 1 - 3 ].…”

“…Vaccine effectiveness: we estimated vaccine effectiveness (VE) from case-control study using the following formula [ 3 , 19 , 20 ]. VE= 1-RRProtective≈1-ORProtective; VE = [1- AOR vaccinated Vs unvaccinated] x 100.…”

“…VE= 1-RRProtective≈1-ORProtective; VE = [1- AOR vaccinated Vs unvaccinated] x 100. Where, RRProtective is the protective relative risk associated with vaccination, which can be approximated by the protective odds ratio (ORProtective), in rare diseases such as measles [ 19 ), 20 ]. We estimated VE in children aged 9-59 months because routine measles vaccination in Ethiopia starts at 9 months of age and this outbreak mainly affected children aged ≤59 months.…”

The economic burden of measles in children under five in Uganda

“…Recognized shortcomings in the vaccine effectiveness in Uganda include settings where the cold chain does not perform adequately [16] and where there is a high prevalence of malaria and HIV [17] . Additionally, behavioral factors can bolster the spread of measles: crowded water points [18] and healthcare facilities without effective triage [19] contributed to two separate outbreaks in 2015 and 2016 in Western and Eastern Uganda.…”

Effect of Schistosoma mansoni infection and its treatment on antibody responses to measles catch-up immunisation in pre-school children: A randomised trial

“…In a study among household contacts of measles patients in Uganda, vaccine effectiveness was found to be only 74% [16]. Recent measles outbreaks in Uganda have been associated, similarly, with evidence of low effectiveness of single-dose measles vaccine (70–75%) [17, 18] compared with other settings (median 84% for immunisation at 9 months, 92.5% for immunisation at 12 months) [19]. Catch-up and booster immunisation on “child days” is offered in Uganda to address this problem.…”