Distribution of HV-1 Subtype C over Time in African Countries.

HIV-1 subtype C was first discovered in Ethiopia, South Africa and Malawi in the early 1980s and has since spread to Southern Africa as well as other countries in Europe (e.g. Russia;1), Asia (e.g. India, China; 2, 3 ) and South America (Brazil; 4) where subtype C has become most predominant. Concomitant with the increase in subtype C in the different countries, there has been a corresponding increase in HIV prevalence rates (as shown in the UNAIDS maps) implying a causal relationship between the two observations.




In previous investigations aimed at correlating HIV prevalence rates and subtype C prevalence, it was found that HIV prevalence rate was lower in Malawi during the early years of the epidemic (2% in 1989) when the frequency of subtype C was at low levels. The rate has now increased to about 18% (2001) and this is at >90% subtype C prevalence (5). This observation supports the hypothesis of the causal relationship between subtype C prevalence and HIV prevalence rates.

Based on an estimation of the progression of subtype C over the years since the disease was first reported in the 1980s (sequence data), the distribution and numbers of this subtype have increased and spread throughout most countries in Africa. Subtype C increased more dramatically in the early 1990s where countries with a subtype C frequency of >80% increased from 3 in the previous years to 5 in the early 1990s and more in the Southern African countries in recent years.

There is little molecular epidemiology information available for countries such as Namibia, Lesotho and Swaziland, but it is believed that subtype C is the major circulating subtype in these countries as well.


References:


1. Bobkov AF, Pokrovskii VV, Selimova LM, Kazennova EV, Karaseva NG, Ladnaia NN, Kravchenko AV, Cheingsong-Popov R, Veber D. 1997.  Genotyping and phylogenetic analysis of HIV-1 isolates circulating in Russia. Vopr Virusol. 42 (1):13-6. Russian. [Medline]

2. Yu XF, Chen J, Shao Y, Beyrer C, Lai S. 1998. Two subtypes of HIV-1 among injection-drug users in southern China. Lancet 35 (9111): 1250 [Medline]

3. Shankarappa R, Chatterjee R, Learn GH, Neogi D, Ding M, Roy P, Ghosh A, Kingsley L, Harrison L, Mullins JI, Gupta P. 2001. Human immunodeficiency virus type 1 env sequences from Calcutta in eastern India: Identification of features that distinguish subtype C sequences in India from other subtype C sequences. J Virology 75 (21): 10479-10487. [Medline]

4. Soares MA, de Oliveira T, Brindeiro RM, Diaz RS, Sabino EC,  Brigido L, Pires IL, Morgado MC, Dantas MC, Barreira D, Teixeira PR, Cassol S, Tanuri A. 2003. A specific subtype C of human immunodeficiency virus type 1 circulates in Brazil. AIDS 17: 11-21. [Medline]

5. McCormack GP, Glynn JR, Crampin AC, Sibande F, Mulawa D, Bliss L, Broadbent P, Abarca K, Ponnighaus JM, Fine PEM,  Clewley JP. 2002. Early evolution of the human immunodeficiency virus type 1 subtype C epidemic in rural Malawi. J. Virology 76 (24): 12890-99. [Medline]


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