Transmission of Mycobacterium Tuberculosis and the Causes of Generation of Recurrent Tuberculosis Cases in Latvia. Summary of the Doctoral Thesis

Abstract

Latvia is among these countries in the world where there still are many cases of multi-drug resistant (MDR) tuberculosis (TB). To follow emergency and spread of these extremely dangerous TB forms, for the first time in Latvia we used methods for molecular epidemiology of TB, like genotyping of M.tuberculosis (MT). By providing the risk assessment of recent TB transmission from 1995 to 2002, we founded that the epidemic of MDR TB was associated with nosocomial MDR MT reinfection among patients, previously continuously treated in TB hospitals. We identified two MDR MT genotypes, i.e., Beijing and LAM9, spread in the community during that period of time. The gradual implementation of the infection control (IC) measures in TB hospitals was started in 1997 and completed by 2003 with the development of the first TB infection control plan and implementation of it in TB hospitals. To decrease the risk of nosocomial TB transmission, a strict adherence to IC measures in hospitals and ambulatory treatment is required. TB transmission risk analysis was repeated and reviewed after the implementation of IC measures when we found the decrease of range of recent MDR TB transmission and we did not find definite links among hospitalized MDR TB patients. As a result of implemented IC strategy the epidemiology of TB, especially MDR-TB, has changed. Until 2002 the most important risk factor for MDR-TB epidemic was nosocomial MDR MT transmission. After implementation of IC program, a reduction of recent transmission of MDR MT was observed. The effectiveness of TB infection control measures, including the necessity and promotion of TB diagnostics and treatment on ambulatory basis were demonstrated in this doctoral thesis an in future also it should be an important component in Latvian National TB program.