Tracing TB transmission in the Philippines through diversity of M. tuberculosis strains

Mycobacterium tuberculosis

Filipinos are as likely to get PTB from their neighbors as with a family member who has the disease; scientists suggested after a recent study found different strains of Mycobacterium tuberculosis from PTB patients living in the same households.

Seeking to link the diversity in M. tuberculosis strains to the epidemiology of PTB in the Philippines, the collaboration of Filipino and American researchers revealed that at least 5% of the pairs of patients who live in the same household have strains of M. tuberculosis that do not match at all.

Two of the three DNA testing employed unanimously showed that only about 62.5% of the strains of M. tuberculosis among patients living together matched. The other one of the three DNA testing employed showed that only 37.5% of the pairs of patients had matching strains. Overall, the three DNA tests revealed great probability of finding individuals living together with completely different strains of the PTB bacterium.

The differences in strains of the bacterium in each household imply that each patient gets the infection from different sources and not merely due to cross-contamination among family members.

Based on the findings, researchers cautioned about taking for granted the importance of community-based transmission in the spread of the disease. While it is easy to assume that cases of two PTB patients in a household may have resulted from cross-transmission in the home, results indicates that community-based transmission is also common.

Tracking down the strains and how these are passed on from person to person provide clearer glimpse on how PTB is being spread in communities. Ultimately, according to the researchers, learning about from which the strains came from and to where they go next can be a basis for future programs in the prevention and control of the disease.

REFERENCE:  Sia, I., Buckwalter, S., Doerr, S., Lugos, S., Kramer, R., Orillaza-Chi, R., Quelapio, M., & Tupasi, T., Wengenack NL. (2013). Genotypic characteristics of mycobacterium tuberculosis isolated from household contacts of tuberculosis patients in the philippines. BMC Infctious Diseases, 13(1), 571. Retrieved from http://www.biomedcentral.com/1471-2334/13/571



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