Ziraba et al. BMC Public Health 2011, 11:663 http://www.biomedcentral.com/1471-2458/11/663 have never tested would like to do so and this gives hope that eventually most people will get tested if efforts of reaching them are intensified. As often happens with other forms of health care utiliza- tion, there were significant differences in testing and coun- selling by socio-demographic characteristics. For example, gender differentials were confirmed in the multivariable analyses where the findings showed that women were more likely to have had either type of testing and counsel- ling compared to men. An earlier national survey carried out in 2003 showed that only 13.1% of women and 14.3% of men in Kenya had been tested at the time of the survey, while the most recent national survey showed that 56.5% of women and 39.9% of men had ever been tested and received results [10]. The apparently widening gap for HIV testing and counselling between women and men might be due to increased testing among women in PMTCT pro- grams. It is also not clear whether the very low levels of PITC among men is majorly an issue of women having more contact with the health care system or men are more likely to opt out of PITC when it is offered. Secondary or higher education was found to be asso- ciated with higher likelihood of having had CITC. This is in line with a common observation that individuals with higher education levels tend to use more health care services as compared to those with low or no formal edu- cation [27,34,35]. This observation did not however hold true for PITC and it is not obviously clear why this was the case. As expected, low HIV/AIDS-related knowledge was associated with lower usage of CITC- but not PITC, since knowledge is important in initiating and making a decision to seek care. These findings suggest that when a client is offered the option of getting tested, their chances of accepting to participate are neither influenced by their educational level attainment nor prior HIV/AIDS-related knowledge levels. Marital status was also an important determinant of HIV testing. Not only can an HIV-positive result lead to divorce or separation [36], the death of a spouse from suspected AIDS may motivate the surviving spouse to seek testing. This might explain the finding observed in this study that divorced/separated/widowed individuals were more likely to have had CITC compared to married individuals. The finding that CITC among married indi- viduals was low might be related to the false notion that people in stable marital partnerships are at a lower risk of contracting HIV yet recent evidence suggest that most new infections are taking place among married indivi- duals who were previously thought to be a low risk group [37,38]. The significantly lower likelihood of the never married women having had PITC might be a reflection of their limited contact with the health care system as com- pared to their married counterparts who mainly make contact for obstetric reasons. Page 8 of 10 The finding that those who were HIV-positive were more likely to have been tested before confirms earlier evidence that individuals who feel that they are at risk, have been exposed or are symptomatic are likely to seek testing [26]. This is a trend prevention programs would not want to see continue in a generalised epidemic because individuals who perceive themselves to be at low risk or asymptomatic are not necessarily uninfected and might continue to fan the epidemic. The Luhya ethnic group was less likely to have had either CITC or PITC compared to Kikuyu and yet in this population the Luhya have the second highest HIV preva- lence at 12% compared to 8% among the Kikuyu ethnic group in the slums[39]. We could not find a plausible explanation, so future ethnographic research should inves- tigate this observation. While wealth has been found to be associated with use of testing and counselling in other stu- dies, this was not the case in this population [40,41]. This might be related to the fact that there is little variability in terms of wealth among the urban poor residents in the slums, but also the fact that the monetary cost involved in getting counselling and testing is too minimal to be a bar- rier to accessing the service. Overall, there are two main policy implications of our findings: i) the need to increase overall testing coverage and ii) the need to address disparities in HIV testing across social groups. While there has been some improvement in the proportion of individuals ever tested over the years, a substantial proportion have never tested and do not know their status and thus need to be reached. With approxi- mately 41% of all those ever tested having been tested through PITC, proponents of integration of HIV testing into routine medical care would welcome this observation and recommend its promotion further. Also, based on our results, it appears that men are being left behind in terms of HIV testing. Given the high level of sero-discordance in Kenya as reported in an earlier survey and the low level of awareness of its existence, targeting couples for testing and counselling might help increase proportion of males who get tested and thus potentially reduce the risk of new infections [9]. A strategy, such as encouraging male part- ners to accompany their partners and participate in PMTCT antenatal clinics could help increase the propor- tion of men testing and strengthen their role as partners in the fight against the epidemic. Limitations In this study, information about HIV-testing status was based on self reported responses. This could be poten- tially affected by recall bias if the test was offered a long time ago, and it could also be affected by the tendency of respondents preferring to give socially desirable answers. Measurement of stigma, a key variable, may not have been satisfactory due to insufficient questions to cover