Abstract:
This study was part of a larger cross-sectional survey that was evaluating tuberculosis (TB) infection in
humans, livestock and wildlife in the Serengeti ecosystem in Tanzania. The study aimed at evaluating the
genetic diversity of Mycobacterium tuberculosis isolates from TB patients attending health facilities in the
Serengeti ecosystem. DNA was extracted from 214 sputum cultures obtained from consecutively enrolled
newly diagnosed untreated TB patients aged 18 years. Spacer oligonucleotide typing (spoligotyping)
and Mycobacterium Interspersed Repetitive Units and Variable Number Tandem Repeat (MIRU-VNTR)
were used to genotype M. tuberculosis to establish the circulating lineages. Of the214 M. tuberculosis
isolates genotyped, 55 (25.7%) belonged to the Central Asian (CAS) family, 52 (24.3%) were T family (an
ill-defined family), 38 (17.8%) belonged to the Latin American Mediterranean (LAM) family, 25 (11.7%) to
the East-African Indian (EAI) family, 25 (11.7%) comprised of different unassigned (‘Serengeti’) strain
families, while 8 (3.7%) belonged to the Beijing family. A minority group that included Haarlem, X, U and
S altogether accounted for 11 (5.2%) of all genotypes. MIRU-VNTR typing produced diverse patterns
within and between families indicative of unlinked transmission chains. We conclude that, in the
Serengeti ecosystem only a few successful families predominate namely CAS, T, LAM and EAI families.
Other types found in lower prevalence are Beijing, Haarlem, X, S and MANU. The Haarlem, EAI_Somalia,
LAM3 and S/convergent and X2 subfamilies found in this study were not reported in previous studies in
Tanzania.
