The involvement of Beijing and CAS1-Delhi clades in paediatric TB patients suggests that these two lineages play a major role in ongoing active transmission.
The predominant genotypes of Mycobacterium tuberculosis are reported to be the Central Asian strain 1 (CAS1) and Beijing families.Mycobacteriumtuberculosis down-regulates host pro-inflammatory cytokines, which are essential for protection against infection.
Also TbD1 analysis (M. tuberculosis specific deletion 1) confirmed that CAS1 was of "modern" origin while EAI isolates belonged to "ancestral" strain types.Prevalence of CAS1 clade was significantly higher in Punjab (P < 0.01, Pearsons Chi-square test) as compared with Sindh, North West Frontier Province and Balochistan provinces.
The fact that the predominant strain, CAS1, is not associated with drug resistance is encouraging and suggests that an effective tuberculosis control program should be able to limit the high incidence of disease in this region.