<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (June 2008) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (June 2008) (Learn how and when to remove this template message) </Td> </Tr> <Table> <Tr> <Th_colspan="2"> Human immunodeficiency virus </Th> </Tr> <Tr> <Td_colspan="2"> </Td> </Tr> <Tr> <Td_colspan="2"> Phylogenetic Tree of the SIV and HIV viruses . </Td> </Tr> <Tr> <Th_colspan="2"> Virus classification </Th> </Tr> <Tr> <Td> Group: </Td> <Td> Group VI (ssRNA - RT) </Td> </Tr> <Tr> <Td> Family: </Td> <Td> Retroviridae </Td> </Tr> <Tr> <Td> Genus: </Td> <Td> Lentivirus </Td> </Tr> <Tr> <Th_colspan="2"> Species </Th> </Tr> <Tr> <Td_colspan="2"> <Ul> <Li> Human immunodeficiency virus 1 </Li> <Li> Human immunodeficiency virus 2 </Li> </Ul> </Td> </Tr> </Table>

In parts of the world other than the united states aids is transmitted primarily through