Original Article http://mjiri.iums.ac.ir Medical Journal of the Islamic Republic of Iran (MJIRI) Med J Islam Repub Iran. 2019(4 Dec);33.130. https://doi.org/10.47176/mjiri.33.130 The spatial analysis of annual measles incidence and transition threat assessment in Iran in 2016 Abolfazl Mohammadbeigi1, Seyed Mohsen Zahraei2, Azam Sabouri2, Azadeh Asgarian3, Sima Afrashteh4, Hossein Ansari*5 Received: 6 Oct 2018 Published: 4 Dec 2019 Abstract Background: During the past years, due to the increase in immunization coverage and promotion of surveillance data, the incidence of measles decreased. This study aimed to determine the measles incidence risk, to conduct spatial mapping of annual measles incidence, and to assess the transition threat in different districts of Iran. Methods: A historical cohort study with retrospective data was conducted. The measles surveillance data containing 14 294 cases suspected of having measles in Iran were analyzed during 2014-2016. WHO Measles Programmatic Risk Assessment Tool was applied to calculate and map the incidence of measles in each district, to determine the annual incidence rate, and to conduct spatial threat assessment risk. Threat assessment was measured based on factors influencing the exposure and transmission of measles virus in the population. The annual measles incidence rate and spatial mapping of incidence in each Iranian district was conducted by Measles Programmatic Risk Assessment Tool. Data were analyzed by descriptive statistics in Excel 2013 and Arc GIS 10.3. Results: Of 14 294 suspected cases, 0.6% (CI 95%: 0.599-0.619) were identified as clinically compatible measles, 0.280 (CI 95%: 0.275-0.284) as confirmed rubella, 0.52% (CI 95%: 0.516-0.533) as epi-linked measles, 4.6% (CI 95%: 0.450-0.464) as lab-confirmed measles, and 94% (CI 95%: 93.93-94.11) were discarded. The annual incidence rate in cases per 100 000 populations increased from 0.0726, (CI 95%; 0.0714-0.0738) in 2014 to 0.1154 (CI 95%; 0.1135-0.1173) in 2016, and the 3-year incidence rate during the study period was 1.032 (CI 95%; 1.017-1.047) and the annual average was 0.3442 (CI 95%; 0.3387-0.3496). Conclusion: The average annual incidence rate of measles in Iran was low, but after a 11-fold increase in the number of measles cases in 2015, the number of measles cases decreased to more than 7-times in 2016. However, maintaning a high immunization coverage of measles and timely vaccination can be effective in reaching the goal of measles elimination. Keywords: Incidence rate, Iran, Measles, Surveillance, Spatial mapping Conflicts of Interest: None declared Funding: None *This work has been published under CC BY-NC-SA 1.0 license. Copyright© Iran University of Medical Sciences Cite this article as: Mohammadbeigi A, Zahraei SM, Sabouri A, Asgarian A, Afrashteh S, Ansari H. The spatial analysis of annual measles incidence and transition threat assessment in Iran in 2016. Med J Islam Repub Iran. 2019 (4 Dec);33:130. https://doi.org/10.47176/mjiri.33.130 Introduction According to the World Health Organization (WHO) re- (2). During the past years, the routine immunization cover- ports, the measles cases showed a high speed decreasing age was increased and the surveillance system data were trend in morbidity and mortality in the recent years (1). Iran improved and, consequently, the disease incidence de- is one of the countries in the Eastern Mediterranean Region creased (3-7). Thus, the endemic virus transmission have ______________________________ Downloaded from mjiri.iums.ac.ir at 19:21 IRST on Tuesday September 28th 2021 [ DOI: 10.47176/mjiri.33.130 ] Corresponding author: Dr Hossein Ansari, [email protected] ↑What is “already known” in this topic: 1. Neuroscience Research Center, Faculty of Health, Qom University of Medical During the past years, the routine immunization coverage of Sciences, Qom, Iran measles was increased and the surveillance quality was 2. Centre for Communicable Diseases Control, Ministry of Health and Medical improved. Consequently, the incidence of measles decreased Education, Tehran, Iran and the endemic virus transmission was interrupted in Iran. 3. Qom University of Medical Sciences, Qom, Iran 4. Bushehr University of Medical Sciences, Bushehr, Iran →What this article adds: 5. Health Promotion Research Center, Department of Epidemiology and Biostatistics, The annual incidence rate of measles in Iran was low; the Zahedan University of Medical Sciences, Zahedan, Iran average annual incidence rate was 3.442 per 1 million people. The annaul incidence rate in 2014 was 0.726 per 1 million, which suddenly increased to more than 11-fold in 2015. However, the annual incidence rate decreased to 1.154 per 1 million in 2016 by supplimentary immunization activities. Annual measles incidence in Iran already been interrupted in Iran (2). disease and the vaccination status of suspected cases were In the early 1980s, regular outbreaks of measles occurred assessed. Four measles classification in surveillance data in Iran and 30 000 to 50 000 cases of measles were reported were used in data analysis. The clinical case of measles is annually (2). After starting the expanded immunization defined as a person with fever and maculopapular rash that program in Iran, the number of measles cases decreased and have cough, coryza, or conjunctivitis and have the measles- by the nationwide campaign of measles-rubella in 2003, the specific IgM antibodies. However, the laboratory classifi- measles cases decreased to zero (2-4). During the 5 years cation outline should be applied in countries with low inci- after the catch-up campaign during 2004–2008, the inci- dence or elimination phase. The laboratory classification dence of measles was 0.2 cases per 1 000 000 persons and scheme to define each case classification, including labor- 103 laboratory-confirmed measles cases were registered atory-confirmed, epidemiologically confirmed, clinically (8). According to our recent study, the overall immuniza- confirmed, and discarded, was based on WHO protocol of tion coverage for all routine vaccines in Iran was 96.8% (5). measles surveillance (15). During 2014-2016, the number Moreover, the coverage of MMR1 and MMR2 vaccine in of lab-confirmed measles cases was 653, epi-linked mea- the outskirt area of large Iranian cities was estimated as sles 75, and clinically compatible measles 87, respectively. 97.1% and 94.9%, respectively (5, 9). However, the high- Therefore, the total number of measles cases during 2014 est delay in vaccination occurred in MMR2 with 74.9% (9). to 2016 was 815. However, from 2000, effective efforts to eradicate measles Threat assessment of measles is evaluated based on fac- have slowed, as the disease and mortality rates decreased in tors that may influence the risk of exposure and transmis- the world (2, 7). Nevertheless, based on our recent analysis, sion of measles virus among people. The threat assessment there was not any inequity in immunization coverage indicators are based on 4 indexes: (1) reported measles among Iranian children according to demographic charac- cases among specific age groups, (2) recent measles cases teristics; however, the prevalence of immunization delay reported in a bordering district, (3) population density, and was higher in migrant population (10). Moreover, inade- (4) presence of vulnerable population groups (VPGs). The quacy in MMR immunization is related to place of living, presence of VPG was assessed by local knowledge of the mother’s education, and immigration, which can be associ- EPI manager at the national or district level. These groups ated with occurrence of measles (11). This study aimed to are defined by WHO and based on the guideline of measles determine measles incidence risk, to conduct spatial map- programmatic risk assessment tool (14). Moreover, these ping of annual measles incidence, and to assess the transi- definitions for VPG were used in other studies (1, 16, 17). tion threat in different districts of Iran. VPGs included 8 different factors in people that increased the risk of measles outbreaks, which have been mentioned Methods in our recent study (7). The measles surveillance data of Iran during 2014-2016 This study was approved by the ethical committee of were analyzed in a historical cohort study with retrospec- Qom University of Medical Sciences (IR.MUQ.REC. tive data. The measles surveillance system in Iran, as a ro- 197.029 code). The authors reported the overall results of bust communicable diseases surveillance system, is respon- the study, and thus it was impossible to identify the pa- sible for collecting and reporting surveillance data (12) and, tients. based on WHO standard recommendations, should detect and report all measles cases (2). Moreover, measles surveil- Data analysis lance data, the mapping of all districts of Iran in the Geo- The WHO measles programmatic risk assessment tool graphic Information System (GIS) shape file, population was used for data analysis. This tool was developed to esti- size in 2016 census for each district, and the EPI manager mate the risk point score of measles outbreak in each region assessment at the national or district level were used in data based on surveillance data, population size, and vaccination analysis. Based on the population size in 2016 census in coverage, surveillance quality indicators of measles, and Iran and the area of each district, population density was presence of VPGs. Moreover, the shape files of all Iranian estimated and the annual incidence rate for measles was districts were used to map the spatial incidence of measles. calculated. Finally, according to the incidence rate in 2016, Furthermore, the annual measles incidence rate and spatial Downloaded from mjiri.iums.ac.ir at 19:21 IRST on Tuesday September 28th 2021 [ DOI: 10.47176/mjiri.33.130 ] the spatial mapping of measles incidence was depicted for mapping of incidence in each Iranian district was con- each district.