Ziraba et al. BMC Public Health 2011, 11:663 http://www.biomedcentral.com/1471-2458/11/663 individuals ever tested among those with no formal edu- cation was higher (56%) than that of individuals with pri- mary or secondary education. There were no significant differences in proportions of individuals who had ever been tested by wealth status index. A higher proportion of individuals (60%) categorised as highly mobile had had testing and counselling before than the less mobile ones (52%). Figure 1 shows the proportion of those with prior knowledge of their HIV status and the current HIV sta- tus as determined in this study. Among individuals who tested negative, 51.4% did not know their status at the time of the study. Among those who tested positive, approximately 43% did not know their HIV status while among those who did not test in this study, 45% did not have knowledge of their HIV status. Table 2 shows a further breakdown of those who had never been tested by intention to test in the future. Over- all, approximately 5% of respondents did not intend to test at all in the future (Table 2). The proportion of indi- viduals who did not intend to test seems to increase with age and was higher among males, residents of Korogocho and among those with no formal education. The unmet need for HIV testing (proportion of all respondents who had never been tested and desired to be tested) was about 42% and was highest among younger individuals under 20 and over 40 years of age, among those who have never been married, males and was least among those with tertiary level education. Table 3 shows multivariate analysis results for determi- nants of HIV testing status with “never tested” as the base outcome- that is, PITC and CITC are being com- pared with those who had never tested. The estimates presented here for each variable are adjusted, controlling for all other variables in the model. Males had signifi- cantly lower odds of having had CITC (OR 0.47; p value Figure 1 Percentage distribution of prior knowledge of one’s HIV status by current HIV status as established in this study. Page 5 of 10 < 0.001) and PITC (OR 0.16; p value < 0.001) compared to females holding all else constant. Generally, control- ling for all other variables, the odds of testing tended to decrease with age for both CITC and PITC although non-significant results were observed for age categories 20-29 years and 50 or more years. Individuals with sec- ondary and higher education had higher odds of having had CITC compared to their counterparts with primary education level but there were no significant differences for PITC. The Luhya ethnic group compared to the Kikuyu ethnic group were significantly less likely to have previously been tested for HIV through either CITC (OR 0.65; 95% CI, 0.48-0.87) or PITC (OR 0.67; 95% CI, 0.47- 0.95). Divorced/widowed or separated individuals had approximately 65% higher odds of having CITC than married individuals. The never married had lower odds of having had CITC (OR 0.71; 95% CI, 0.54-0.93) and PITC (OR 0.28; 95% CI, 0.19-0.40) compared to the married. Individuals who were found to be HIV-positive in this study and those whose HIV status was not determined had higher odds of having had CITC (OR 1.60; 95% CI, 1.15-2.22 and OR 1.39; 95% CI, 1.08-1.80), respectively, compared to those who were found to be HIV-negative. Individuals ranked as being among the lowest 20% on HIV/AIDS-related knowledge index had lower odds of having had CITC compared to those in the second 20% (OR 0.64, p value < 0.01). The differences were not signifi- cant for rest of the knowledge index categories. Individuals who thought that knowing one’s HIV status was not good were less likely to have had either CITC (OR 0.32; 95% CI, 0.16-0.63) or PITC (OR 0.16; 95% CI, 0.06-0.43) compared to those who thought it was good to know one’s HIV sta- tus. Lack of knowledge of location of health care facilities that offer HIV/AIDS-related services was significantly associated with lower odds of both CITC (OR 0.60; 95% CI, 0.48-0.74) and PITC (OR 0.79; 95% CI, 0.62-0.99). Wealth status index, area of residence and multiple sexual partnerships were neither associated with CITC nor PITC. Discussion The focus of this paper was to examine the state of HIV testing and counselling and its determinants in Nairobi informal settlements. It is widely acknowledged that know- ing one’s HIV status is a major step in the prevention, initiation of treatment with antiretroviral drugs, preven- tion and treatment of opportunistic infections and use of psychosocial support services. In spite of this, many indivi- duals in sub-Saharan do not know their HIV status. Our results corroborated those of previous studies which found uptake of voluntary counselling and testing services to be low [8,9,31]. Compared to Nairobi city as a whole, slum settlements have a lower proportion of women and men who have ever been tested for HIV. This underscores the