A snapshot of the biodiversity and clustering of Mycobacterium tuberculosis in Oman using spoligotyping

SETTINGS

National Tuberculosis Reference Laboratory, Central Public Health Laboratory, Ministry of Health, Oman.

OBJECTIVE

To use spoligotyping to explore the genetic population structure and clustering of Mycobacterium tuberculosis isolates among nationals and immigrants in Oman.

METHODS

Using spoligotyping, we characterised all available isolates from 2007, and randomly selected isolates from 2005 and 2006. A total of 312 clinical isolates from the same number of patients diagnosed with tuberculosis (TB) in 2005-2007 were included in the study.

RESULTS

Of 312 isolates, 69% were in clusters ranging from 2 to 38 isolates. The proportion of clustering was 58% among 2005-2006 samples and 67% among 2007 samples, with higher clustering among Omanis than among immigrants. The study showed that M. tuberculosis Indian family lineages, CAS1_Delhi, CAS and EAI5 were the predominant strains. Around 50% of the immigrants shared strains with Omanis. Twelve of the 19 INH-monoresistant strains and the two multidrug-resistant strains were in clusters (P = 0.81).

CONCLUSION

This study demonstrates the predominance in Oman of the strain family commonly found on the Indian sub-continent. A high proportion of immigrant strains were in the same clusters as Omani strains. To better ascertain the transmission dynamics of M. tuberculosis, we recommend that stringent molecular and conventional epidemiological methods be applied.

Towards the elimination of tuberculosis in a developing country: 25 years of tuberculosis control in Oman

OBJECTIVE

To analyse trends of tuberculosis (TB) in Oman (1981-2005) in relation to the socio-economic development of the country.

METHODS

Data were used from the National Tuberculosis Control Programme (NTP). Information on TB cases' age, sex and type were obtained from the national book (1981-1991) and the computer database (1992-2005).

RESULTS

TB notification rates among Omani nationals declined by more than 85% from 1981 to 1995. During the period 1981-1993, the TB notification rate declined by around 15% per year, compared to only 3.6% per year in subsequent years. Males and the age group > or = 50 years have higher rates than females and younger age groups, respectively. Non-nationals contributed 21% of all TB cases notified and 40% of all smear-positive cases. Of cases among nationals notified between 2004 and 2005, 95% had a family income lower than the national average.

CONCLUSION

Although TB notification in Oman has declined by more than 85% over the last 25 years, the decline has slowed down over the last 10 years, requiring a detailed analysis of existing TB control measures and implementation of additional measures for TB elimination.