Shorunke et al. BMC Public Health (2019) 19:1636 https://doi.org/10.1186/s12889-019-8012-6 RESEARCH ARTICLE Open Access Descriptive epidemiology of measles surveillance data, Osun state, Nigeria, 2016–2018 Folajimi O. Shorunke1* , Oluwatoyin Adeola-Musa2, Aisha Usman3, Celestine Ameh3, Endie Waziri3 and Stephen A. Adebowale4 Abstract Background: Globally, an estimate of 254,928 measles cases in 2015 and 89,780 deaths in 2016 occur annually. In Nigeria, measles is the fifth leading causes of under-five child mortality with 342 confirmed cases found in the first 9 epidemic weeks in some states including Osun State. We described the distribution, trend and make projection of measles cases in Osun State. Methods: The Osun State surveillance weekly reporting data on measles cases from all its 30 Local Government Area (LGA) were reviewed, from January 2016 to December 2018 (n = 1205). Data were analyzed using descriptive statistics and a multiplicative time series model (MTSM). The MTSM was used to determine the trend, seasonality in the data and make projections for 2019 and 2020. Results: Cases of measles were reported across the 30 LGAs of the state between January 2016 and December 2018. The rate of reported cases of measles was 20.2, 34.4 and 28.8 per 100,000 populations in 2016, 2017 and 2018 respectively in Ede south LGA where the highest rates were reported in the 3-year period. Out of the three studied years, year 2017, recorded the highest number of reported cases of measles in Osun State. The trend line for the 3- year period showed a positive correlation (r = + 0.4979, p = 0.056). The computed quarterly variation for the studied years was 1.094 for the 1st quarter, 1.162 for the 2nd quarter, 0.861 for the 3rd quarter and 0.888 for the 4th quarter. A quarterly projection for 2019 and 2020 showed an increasing trend with the second quarter of each year likely to have the highest reported cases of measles. Conclusions: Ede south LGA has the highest proportion of reported measles cases in Osun State. Measles cases may increase in years ahead, but the second quarter of a year has the highest number. Government should strengthen the existing framework on measles reduction and more attention should be given to the second quarter of each year. Keywords: Measles surveillance, Seasonal variation, Trend, Osun-state Background by WHO in endemic countries range between 0.05–6% Measles disease is caused by a morbilli virus of the para- [3]. It is a highly infectious disease that will infect about myxoviridae family and is a contagious respiratory infec- 90% of unvaccinated individuals exposed before the age tion. Globally, an estimate of 254,928 measles cases and of 10 [4]. On 16th September 2010, World Health 89,780 deaths occur annually [1] and the measles case Organization (WHO) countries in the European region fatality ratios (CFRs) was estimated to be 0.1% [2] in the came up with a resolution to renew their commitment developed world. Recent estimates of measles CFRs used to eliminate measles and rubella by the year 2015, com- ing up with several criteria to eliminate the disease in the region, including protection of Europeans against * Correspondence: [email protected] 1Nigerian Field Epidemiology and Laboratory Training Program, Abuja, measles and rubella infection [5] which had affected sev- Nigeria eral European countries including Romania and Italy Full list of author information is available at the end of the article © The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Shorunke et al. BMC Public Health (2019) 19:1636 Page 2 of 8 with the largest outbreak reported in southern Italy. vaccination and immunization in Nigeria. The campaign Children below the age of 15 had a national incidence of targets children under-five years between 2008 and 2013. 738/100,000 in 2002 and 544/100,000 in 2003, estimated The vaccine of choice is mcv which is administered at 9 to more than 100,000 cases within the age group [6]. months of age, eligible children however get access to Despite intensive vaccination activities in the European more doses through SIA’s conducted one or more times region, cases were still reported [7]. in a year. Findings show that high administrative coverage Africa and Southeast Asia contributed 70% of the 39.9 was observed at the national level but low at the level of million global burdens of measles in year 2000 and also Local Government Area. The most recent national survey 84% of the global measles-related deaths. Only eleven of data on immunization coverage in Nigeria reveals that for the African countries including Ethiopia, contributed children aged 12–13 months, the national coverage for 66% of this deaths [8]. Sub-Saharan African countries measles was 41.8% (MICS5–2016-2017). Despite these have the highest morbidity and mortality associated with interventions an increase in the cases of measles is still be- the disease [9]. In this Africa sub-region, the CFR ranges ing experiences [10]. In 2008 there were 9510 cases which from 3 to 5% but can increase to about 30% during increased to 17,248 cases by 2011 [14]mostofwhich severe outbreaks [9]. In Nigeria, measles exhibits a occurred among children [15]. There were about 194 out- seasonal pattern with incidence increasing during the breaks of measles in 2007, 254 in 2008 and 169 in 2009 dry season, usually between November and May [10] [16] in addition, 643 outbreaks were confirmed in and the disease remains the fifth leading cause of under- 83% of the 774 LGAs in Nigeria between epidemic five child mortality in the country [11]. week 1 and 43 of 2013 [17]. The northern part of the The risk of spread and prolonged transmission of mea- country especially Kebbi and Kaduna States had the sles were associated with the presence of a susceptible largest contributions [14]. population, but vaccination with at least two doses of The WHO IDSR surveillance system and response measles vaccine was the most effective measure for the capacity in any country is important and a lack of prevention and control of the disease [7]. Despite the adequate capacity can endanger its population. Unfortu- comprehensive campaign and intervention strategies to nately, Nigeria and most developing countries, lack this improve the uptake of vaccination against childhood dis- capacity hence measles outbreaks are not promptly eases in Nigeria by Nigerian government and international detected, leading to a late or no response hence little agencies, the confirmed cases of measles remain high and public health impact [18, 19]. the case fatality due to the disease is yet to be alleviated The objectives of this study are to describe the geo- [12]. The intervention includes measles-reduction strat- graphical distribution of measles cases reported in Osun egy, partnership of other international organizations com- State, determine its trend and make a 2-year projection of mitted to the support of measles mortality reduction and the disease in Osun-State. These are with the view to pro- based on the outcome of this supports, it is still unpleas- viding situation assessment of the spread of the disease in ant that some states in Nigeria continue to face recurrent Osun State and inform policy that will promote reduction of epidemics including measles [12]. This may be due to in the number of reported cases in the years ahead. the low coverage in the LGA levels or perhaps because maternal antibodies may have neutralized the vaccine Methods antigen before a specific immune response develops. In Study design Osun State, the childhood diseases vaccination coverage We conducted a descriptive secondary data analysis of rate is 57.8% which is below the WHO target of 80% and data from Osun State surveillance weekly reporting data- the state is among states with low vaccination coverage in set. The source of the dataset was the Osun State Minis- Nigeria [13]. try of Health State Epidemiology department. I received In 2005, Nigeria adopted the program of WHO African ethics approval from the Osun State Health Research region on the reduction of morbidity and mortality Ethics Committee (OSHREC) to obtain data from the associated with measles [9, 10]. Nigeria also adopted epidemiology department and carry out the analysis as the program’s goals revisions and strategies instituted required (Reference number OSHREC/PRS/569 T/155). to achieve the goals, this included strengthening infant’s The dataset presented in excel format was from January routine measles immunization coverage, provision of a 2016 to December 2018. Variables extracted include second dose of measles vaccination through supplemen- cases per epidemic weeks, the totals for each year and tary immunization activities (SIA), improving measles the various LGAs reporting in Osun State. case-based surveillance with laboratory confirmation and strengthening the case management [9, 10]. A follow-up Study setting campaign has been conducted since the revision of the Osun State is one of the South-western States in Nigeria, adopted strategies to increase the coverage of childhood predominated by Yoruba speaking indigenes with a Shorunke et al. BMC Public Health (2019) 19:1636 Page 3 of 8 projected population of 4,996,100 in 2018 derived from PL Pn−m SV i SV the 2006 national census.