  UNAIDS has embraced an ambitious global target for the implementation of
treatment for people living with HIV. This 90-90-90 target would mean that, by
2020, 90% of all those living with HIV should know their status, 90% of these
would be on treatment and 90% of these would have fully suppressed plasma viral
loads. To reach this target in the next five years presents a major logistical
challenge. However, the prevalence of HIV varies greatly by risk groups, age,
gender, geography and social conditions. For reasons of effectiveness and
impact the focus must first be on those who are most likely to be infected with
HIV and therefore most likely to infect others. In Kenya the prevalence of HIV
in adults varies by two orders of magnitude among the counties. The effective
implementation of 90-90-90 will depend on first providing ART where the
prevalence of infection is greatest, then to those that are most easily reached
in large numbers and finally to the whole population. Here we use routine data
from ante-natal clinics and national survey data to assess the variation of the
prevalence of HIV among counties in Kenya; we suggest reasons for this
variation, and estimate the effectiveness of targeting the role out of ART. The
highest prevalence occurs in some of the counties bordering Lake Victoria and
these are most in need of ART. These districts in Nyanza Province, account for
31% of all cases in Kenya but make up 10% of the population and cover 1.8% of
the land-area. The highest concentrations of HIV cases are in Nairobi and
Mombasa which account for a further 18% of all cases in Kenya but make up 12%
of the population and cover 0.1% of the land-area. Providing ART in these two
cities will be relatively straightforward given their small geographical area.
