European Society of Mycobacteriology - Instituto Nacional de Saúde ...

OP-9
LAM AND HIV: CORRELATION OR CO-INCIDENCE?
McNerney, Ruth, Mallard, Kim
London School of Hygiene & Tropical Medicine
The deadly synergy between TB and HIV presents a serious challenge to heath and development. Three decades after the
onset of the AIDS pandemic the region with the highest prevalence of HIV infection is sub-Saharan Africa, followed by
the Caribbean and Latin America. Molecular typing methods permit differentiation of M. tuberculosis into strain families
or genotypes. We have undertaken analysis of genotyping data to compare the prevalence of spoligotype lineage with
that of HIV infection. Data was taken from the peer reviewed literature, surveys testing only drug resistant strains or
those not fully describing the genotype population were excluded. The Latin-American-Mediterranean (LAM) lineage are
identified as typically lacking spoligotype spacers corresponding to oligonucleotides 21 to 24 and 33 to 36. They have
been observed in many geographic locations and include the F11 family reported in South Africa. Our analysis suggests
that LAM strains are more frequently found in regions with a high prevalence of HIV. Conversely, they are rare in settings
where HIV has yet to emerge as a major threat to public health. Interestingly LAM genotypes appear less frequent
in African countries such as Uganda, Tanzania and Cameroon which have lower HIV prevalence’s than countries such as
Malawi, Zimbabwe and South Africa where HIV rates are in excess of 10%. Why tuberculosis of this genotype should be
linked to the HIV epidemic remains a matter of speculation. Although socioeconomic and political factors play a significant
role they do not explain the uneven distribution of HIV in sub Saharan Africa. It is now evident that there is diversity
in the interaction of M. tuberculosis with its host and strains of differing genotype appear to elicit subtle but significant
differences in immune response. We present the hypothesis that strains of tuberculosis belonging to the LAM genotype
are associated with enhanced transmission of TB in immunosuppressed populations.
European Society of Mycobacteriology | 30 th Annual Congress | July 2009 | Porto - Portugal
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