Modified Diagnostic Approach and Molecular Epidemiology of Childhood Tuberculosis in Hawassa, Ethiopia ity Testing, Treatment Outcome
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Date
2018-06-04
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Addis Ababa University
Abstract
Childhood TB accounts to 1 million (10%) of the estimated 10.4 million new cases of TB globally. It is known to be the major contributor of childhood morbidity and mortality. The prevalence of childhood TB/HIV co-infection and multidrug resistance (MDR) presumed to have grown up with the advent of HIV. Unfortunately it has been given less attention as a challenge at international level; there are no sufficient epidemiological data even in high burden countries and the effects are not included with the national policies and strategies i.e. is neglected. Due to this scarcity of epidemiological data the attempts that have been made to develop tools for childhood TB diagnosis, treatment, control and to understand how the immunological and pathological responses differ from that of the adult is very little. It is in recognition of these gaps of knowledge and attention that the present work was set with the following objectives: to use modified approach for diagnosis and determine the prevalence of childhood active TB cases, identify the strains of Mycobacterium tuberculosis, determine their drug susceptibility pattern and assess the treatment outcome.
A prospective cross sectional study was done on 700 children clinically suspected for TB and 350 of them were used to determine the prevalence, molecular characterization and drug susceptibility pattern of TB isolates and the remaining 350 were used to evaluate modified childhood TB diagnostic approach. A five year retrospective cross sectional study was also done to evaluate the treatment outcome of children with TB in the study area.
The results showed an overall prevalence of smear positive (7.4%) and Culture confirmed TB cases (9.7%). Drug susceptibility testing showed one (2.9%) MDR case from the isolates and Spoligotyping of 34 isolates revealed 15 different patterns, 11 of which corresponded to Shared International Types (SITs) and 4 to orphan strains. The dominantly identified strains IV
were SIT 53, SIT 149, and SIT 442. The isolates belonged to Euro-American lineage (94.1%) and East-African-Indian lineage (5.9%). A 13.2% incremental yield was obtained due to testing of pooled samples compared to either of the first or second sample using GeneXpert MTB/RIF assay in diagnostic evaluation study. The overall treatment success rate among all children with TB at the study facilities was 39.7%. The lower prevalence of pediatric pulmonary TB could be due to the less sensitive nature of culture and microscopy diagnostic tools thus the modified diagnostic approach may show the real magnitude by increasing case detection. Clustering of strains in spoligotyping suggested an on-going and active transmission of M. tuberculosis in the study area. The identified MDR case showed DST is warranted to optimize the management of childhood TB. The Overall treatment success rate among all children with TB was unsatisfactory compared to WHO target of 85% and 54.7% of children with TB in the study facilities were transferred out. There should be a system to track transfer out cases are on treatment.
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Keywords
Children, M. Tuberculosis, Prevalence, Diagnosis, Drug Susceptibility Testing, Treatment Outcome