Implementation of a National Measles Elimination Program in Iran: Phylogenetic Analysis of Measles Virus Strains Isolated during 2010–2012 Outbreaks

Abstract

Measles virus (MV) causes small and large outbreaks in Iran. Molecular assays allow identifying and the sources of measles imported from neighboring countries. We carried out a phylogenetic analysis of measles virus circulating in Iran over the period 2010–2012. Specimens from suspected cases of measles were collected from different regions of Iran. Virus isolation was performed on urine and throat swabs. Partial nucleoprotein gene segments of MV were amplified by RT-PCR. PCR products of 173 samples were sequenced and analyzed. The median age of confirmed cases was 2 years. Among all confirmed cases, 32% had unknown vaccination status, 20% had been vaccinated, and 48% had not been vaccinated. Genotypes B3 and D8 (for the first time), H1 and D4 were detected mainly in unvaccinated toddlers and young children. Genotype B3 became predominant in 2012 and was closely related to African strains. H1 strains were also found in small and large outbreaks during 2012 but were not identical to Iranian H1-2009 strains. A majority of the Iranian D4 strains during 2010–2012 outbreaks were linked to the D4 strain identified in the Pakistan in 2007. We identified a single case in 2010 belonging to D8 genotype with 99.7% identity to Indian isolates. Although the vaccination program is currently good enough to prevent nationwide epidemics and successfully decreased measles incidence in Iran, the fraction of protected individuals in the population was not high enough to prevent continuous introduction of cases from abroad. Due to increasing number of susceptible individuals in some areas, sustained transmission of the newly introduced viral genotype remains possible.

Poor quality data challenges conclusion and decision making: timely analysis of measles confirmed and suspected cases line list in Southern Nations Nationalities and People’s Region, Ethiopia

“…Most epidemiological analysis of measles surveillance data also showed that the status of more than half of cases was unvaccinated [ 17 – 21 ]. The proportion of vaccinated cases in this study was found to be higher (61.9%) than that of epidemiological analysis of measles surveillance data done in Cameron [ 13 ], Iran [ 22 ], Iraq [ 21 ] and Italy [ 18 ] that showed 49.2%, 20%, 18% and 5.5% of cases were vaccinated respectively. At the time of outbreak, it was concluded that outbreak was due to accumulation of susceptible population.…”

Estimation of measles risk using the World Health Organization Measles Programmatic Risk Assessment Tool, Iran

“…Another study showed that from 221 laboratory-confirmed measles cases during 2004–2009 in Iran, the most portion of cases were from rural areas and immigrant groups from high-incidence countries [17] . Therefore, supplementary immunization of children before starting in school in deprived and outskirt area suggested as an effective practice for decreasing the measles outbreaks risk [18] to protects the susceptible individuals in some areas who have not high enough immunity [19] .…”

Towards measles elimination: Phylogenetic analysis of measles viruses in Turkey (2012-2013) and identification of genotype D8

“…Genotype B3 viruses were found in 49 countries across all WHO regions in 2014 [Mulders et al, ]. Genotype B3 is endemic to much of Africa and is often imported from African countries [Rota et al, , ; Salimi et al, ]. Six B3 genotype cases were clustered in two variants.…”