We present the first data on the molecular epidemiology of HIV-1 in Morocco from the national HIV sentinel surveillance survey data. As of 2005, subtype B is still predominant (76.7%), yet following subtype B, there is a high diversity of non-B subtypes, especially CRF02_AG recombinant (15%). Geographic subtype repartition suggests the co-evolution of a more ancient diffusion of European subtype B, and of a more recent spread of sub-Saharan African strains in some Moroccan regions.
These results demonstrate a high diversity of HIV-1 strains in Morocco. This is different from what was reported in 1997 where the distribution of subtype B, A and F strains in Morocco were 93.5%, 1.0%, and 0.5% respectively . However, these results are consistent with our previous results  and the more recent results described from the Casablanca region . These findings are also consistent with results described in other countries of the region, including the neighbouring West African countries . The increase of HIV non-B subtypes was also recently reported in many Western Europe countries. Studies conducted in France, Spain, Switzerland, and Portugal have found that the proportion of non-B subtypes may exceed 20% [20, 21]. CRF02_AG, which predominates in West Africa, is increasingly more prevalent among the non-B subtypes in these Western European countries.
The overall incidence of HIV-1 in Morocco has been increasing at approximately 15% per year since 2000. The increasing incidence of HIV combined with the identification of additional non-B subtypes raises concerns regarding the control of the current epidemic. The entry of new HIV recombinant viruses is likely the consequence of active exchange between different populations, such as Moroccan groups at risk and persons migrating through Morocco from sub-Saharan Africa. Before 1997, the presence of Sub-Saharan African individuals in Morocco was mostly limited to students and tourists. However, migration of people from sub-Saharan Africa to and through Morocco has been increasing since the late 1990s. In 2007, the Moroccan Ministry of the Interior estimated that approximately 15,000 irregular migrants flow through Morocco each year . In response, the European Union has tightened its boarder control and immigration policies. As a result, many of the migrants settle in Morocco, waiting for an opportunity to cross into Europe. In addition, regular and irregular migrants face many economic and social issues that may increase their risk for HIV transmission. For example, issues such as human trafficking and prostitution could contribute to the circulation of non-B HIV subtypes such as CRF02_AG throughout the country.
The fact that subtype B was more distributed throughout the country, especially in the big-touristic cities (Agadir, Marrakech and Casablanca), suggest this subtype may reflect an older infection. Persons with subtype CRF02_AG were also widely distributed geographically; however, this subtype was not detected in Morocco before 1997, suggesting a more recent epidemic. These findings are also supported by our molecular clock analysis. The other non-B subtypes and recombinants represented more localised transmission due to C, A/C, B/C and A/CRF01_AE strains in the northern part of Morocco.
As the first case of HIV/AIDS in Morocco was reported in 1986, there is an excellent agreement with the TMRCA of HIV-1B of 1983 estimated by molecular clock analysis. Since that date, HIV has been spreading throughout the country, mainly by heterosexual transmission . According to the sentinel surveillance system, the overall HIV prevalence is less than 1% in Morocco. However, even though Morocco is a low prevalence epidemic, HIV/AIDS cases are steadily rising, chiefly in the southern Morocco region of Agadir and neighbouring areas that may represent the epicentre of the epidemic within Morocco .
Our findings should be interpreted in light of study limitations. While our analysis included all HIV positive specimens from the 2004-2005 survey, the sample size was relatively small. Therefore, it is not possible to generalise the results as a national trend in Morocco. In addition, routes of transmission and clinical and immunologic status of the HIV-infected individuals were not available for this study, since they are not required in the surveillance process. However, the present data should prompt us to continue to track the molecular epidemiology of the HIV virus in Morocco at the national level. In this context, reinforcement of preventive measures to limit the spread of the epidemic is crucial. Lastly, by limiting our phylogenetic analysis to only the pol gene region, we may have missed some recombinants and therefore underestimated their distribution. However, our main finding that CRF02_AG is increasing in Morocco, signifying a shift from an epidemic previously dominated by serogroup B, remains true. In conclusion, the results of this study displayed that HIV diversity is more dynamic in Morocco and its pattern is shifting from the European to sub-Saharan one, i.e. with more subtypes non-B, namely the CRF02_AG. However, more studies to confirm the trend observed during this study and to better characterize the molecular HIV epidemic in Morocco will be of great importance. When taken together, these data demonstrate a dynamic evolution in the HIV diversity in Morocco. The emergence of new HIV subtypes are characterised by an important presence of non-B subtypes that appear to be linked to sub-Saharan populations. More data are needed to better understand the factors responsible for the introduction and spread of new HIV-1 subtype epidemics into regions where they did not exist previously.