Molecular epidemiology of M. Tuberculosis transmission in the United Arab Emirates

Usmani, Mohammad Asadullah (2009) Molecular epidemiology of M. Tuberculosis transmission in the United Arab Emirates. Masters thesis, University of Central Lancashire.

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Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis. The people from South East Asian countries constitute the bulk of immigrant resident work force in the United Arab Emirates (UAE) and neighboring Gulf Countries. It is a common believe that TB infected expatriates, are mainly responsible for the spread of the disease.
However, another hypothesis from some scientific community states that there is an additional indigenous TB source in the local community. There are seven Emirates in the United Arab Emirates (UAE) while Abu Dhabi Emirates is the largest among seven. The UAE health authorities vigilantly monitor the threat of numerous infectious diseases including TB. Expatriates are granted resident visa only after screening of health condition and infectious diseases. The Al-Ain Medical District is one of the three Medical Districts of Abu Dhabi Emirate and covers the Eastern Region. Al-Ain has a higher proportion of
Emirati nationals than elsewhere. It represents a true conservative resident population. The study was undertaken to compare the present TB situation with the past and to determine whether this is an imported disease prevalent mostly in either immigrant expatriates or there is an endemic source. The data were collected for the period of 2001 to 2006, analyzed statistically, and compared with past reports. All Epidemiological data and samples were collected from the local hospitals and the UAE district clinics in Al-Am.
The epidemiological data of the study revealed that the prevalence of TB did not change significantly during the last twenty years. The disease is more prevalent in expatriate population in terms of numerical figures, but it is proportional to population size whether expatriates or Emirati Citizens. The prevalence of disease is more pronounced in young adults of working age between 25-30 years rather than the old age groups. Moreover, the female to male ratio was increased in the present study period. Overall, nine different parameters were analyzed.
The study of Restriction fragment length polymorphism (RFLP) of 106 isolates revealed low copy number of 156110 which seemed to be related to South Asian sub-population strain. There was evidence of typical mycobacterium species prevailing for primary infections. The data showed increasing rate of infection by atypical mycobacterium but further molecular biology work is needed to establish a clear conclusion. There was evidence of exogenous and endogenous strains infecting both the Emirati and non-Emirati population with no bias. The molecular technique was of limited discriminatory power because it yielded less polymorphism and low number of 1S6 110 copies. Hence, secondary genotyping would have more benefit for a definite conclusion.
From this study, it may be concluded that the prevalence of TB in UAE has remained more or less stable for the past 20 years. The results also show that expatriate carriers are not the only cause for TB. Molecular-biology gave evidence of remotely acquired and latent sources of infection in the resident population which may be a reason for a stable infectivity
rate. Stringent control measure adopted by Ministry of Health seems to have been successifil. More extended molecular biological work is needed to establish the transmission route and etiology of the disease in the multinational, multi cultured and mixed ethnic population of UAE.

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