Determining the risk of intra-community transmission of tuberculosis in the northwest of Iran through 15 loci MIRU-VNTR typing

Abstract

This study was carried out in order to investigating the effect of travelling on the transmission of tuberculosis from high- to low-burden TB countries. Mycobacteria samples isolated from patients of distinct and relatively co-related countries (Azerbaijan Republic and Tabriz [located in the northwest of Iran]) were analyzed through 15 loci MIRU-VNTR typing method. PCR was done using special primers for each of the loci; then the number of allele repeats for all loci were determined by the size of their fragments. Finally, the created numeric patterns for each isolate were analyzed and clustered, using MIRU-VNTRplus.org website. All 119 isolates dispersing at 106 distinct patterns were composed of 10 clusters with 23 members and 96 unique patterns. Nine and five loci had high and moderate discriminatory power, respectively, but only one of them was poor in clustering. The study showed that 89.08% of TB cases involved resulted from the reactivation pattern and 10.92% were related to ongoing transmission. Although Azerbaijan Republic is a higher-burden TB region than Tabriz and Azerbaijan people make frequent tours to Tabriz to receive low or free medical services, the findings showed no TB transmission from the regions at least during the year of the study.

Role of immigration in tuberculosis transmission to Iran: A systematic review

“…Regarding including and excluding criteria from study, the information of 16 papers was finally analyzed [ Figure 1 ], and the summary of important information is presented in Table 1 . [ 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 ] Methods used for genotyping include insertion sequence 6110-restriction fragment length polymorphism (IS6110-RFLP), spoligotyping, polymorphic GC-rich repetitive sequence-restriction fragment length polymorphism (PGRS-RFLP), mycobacterial interspersed repetitive unit-exact tandem repeat (MIRU-ETR), mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR), and direct repeat-restriction fragment length polymorphism (DR-RFLP). In eight studies, they used a secondary typing method, and eight studies were without a secondary method.…”

“…The majority of intra-community transmission took place between Iranian and Afghan immigrants. The intra-community recent transmission rate was very different, as in Afagi et al .,[ 17 ] Rafiee et al .,[ 21 ] and Asgharzadeh et al . [ 27 ] studies, the rate of intra-community was zero.…”

“…[ 21 ] and Asgharzadeh et al .,[ 27 ] the number of non-Iranians was very low, 3 and 2 cases, respectively; therefore, the intra-community probability would be very low and also they used two methods for typing. However, in the study of Afagi et al .,[ 17 ] although Azerbaijanis represented 24% of the patients, there was no intra-community, and the inter-community transmission among the Azerbaijanis was ( = 10.7%) and among Tabriz people were ( = 11%). It seems, in contrast to the eastern provinces of Iran, Afghan immigrants have not resided in the North West of Iran because of distant and different languages of the Azeri language, and the non-Iranians who have been referred for diagnosis and treatment were from the Republic of Azerbaijan who have common language with people from northwest of Iran and have come to Tabriz for therapeutic tourism to provide medical services at a very low or free cost to treat TB patients, as they have not stayed for a long time in Tabriz to have close contact with different people and also the sample size was low (119 cases); therefore, it did not conclude all samples; as a result, the size of existing clusters was small (2–4 members) and there has not been common cluster between Azerbaijanis and Tabrizis.…”

“…It seems, in contrast to the eastern provinces of Iran, Afghan immigrants have not resided in the North West of Iran because of distant and different languages of the Azeri language, and the non-Iranians who have been referred for diagnosis and treatment were from the Republic of Azerbaijan who have common language with people from northwest of Iran and have come to Tabriz for therapeutic tourism to provide medical services at a very low or free cost to treat TB patients, as they have not stayed for a long time in Tabriz to have close contact with different people and also the sample size was low (119 cases); therefore, it did not conclude all samples; as a result, the size of existing clusters was small (2–4 members) and there has not been common cluster between Azerbaijanis and Tabrizis. [ 17 ] Therefore, there has not been intra-community. Of course, in another study conducted in this region, intra-community was observed to be 1.7%.…”

Trends in Mycobacterium tuberculosis Transmission During a 10-year Period (2006-2016) in the Northwest of Iran by MIRU-VNTR Molecular Typing

“…The low rate of tuberculosis transmission among the population is the characteristic of most low-incidence countries, but cross-border immigration from highincidence countries can affect the incidence and features of tuberculosis in the low-incidence countries (6). The increased migration of high-burden tuberculosis countries such as Afghanistan and the Republic of Azerbaijan has resulted in the increased frequency and resistance of tuberculosis in low-burden cities of Iran as a low-incidence country (7,8). Genotyping approaches of M. tuberculosis are used for epidemiological study, which include DNA fingerprinting methods such as Insertion Sequence 6110restriction fragment length polymorphism (IS6110-RFLP), variable number of tandem repeats (VNTRs) based on mycobacterial interspersed repetitive units (MIRU-VNTR), exact tandem repeat loci-VNTR (ETR-VNTR), whole genome sequencing (WGS), and single nucleotide polymorphisms (SNPs) (9-13).…”