Sero-prevalence and risk factors for hepatitis B virus infection among health care workers in a tertiary hospital in Uganda

Globally there are about 360 million chronic carriers of hepatitis B virus and over one million people die each year as a result of acute fulminant liver disease or hepatitis B virus (HBV) induced cirrhosis and liver cancer [1]. The burden of hepatitis B virus infection is highest in the developing world particularly Asia and sub-Saharan Africa [2–4]. World Health Organization estimates that the prevalence of hepatitis B virus infection in Africa is on average more than 10% [5, 6]. Recent studies carried out in Uganda showed that the prevalence of current hepatitis B virus infection in the general population is about 10% [7].

Although most infections in the developing world occur in childhood and early adulthood, a significant proportion of non-immune adults remain at risk. Hepatitis B virus infection is a recognized occupational hazard as non-immune health care workers (HCW) stand a risk of getting infected from their work place [8–11] . Generally HCW who perform invasive procedures for example surgeons, dentists, emergency workers and those who handle human specimens like the laboratory technicians have been consistently shown to have higher prevalence of hepatitis B virus infection than their counterparts [12–14]. The differences in HBV infection rates may reflect disparities in the risk of exposure to infection [14, 15]. For instance one study conducted among dental students and dentists revealed that a significantly higher proportion of dentists tended to use gloves compared to the dental students [16], while another study showed that 38% of professional HCW were vaccinated compared to only 3.5% of the housekeeping staff in the same hospital [17].

Because available treatment for hepatitis B virus infection does not provide a complete cure, prevention remains crucial [18]. A safe, effective and highly acceptable HBV vaccine has been around since 1982 [19, 20], but its use among HCW in the developing world is low [21–24]. Limited access to vaccination by HCW is a consequence of lack of initiative from governments to formulate policy and guidelines to ensure that all HCW get vaccinated.

Whereas the literature on hepatitis B virus infection in Uganda is growing, there is still paucity of information on HBV among HCW. This paper contributes to this discourse by presenting the prevalence estimates and risk factors for hepatitis B virus infection among health care workers. It also presents an assessment of availability of infection prevention strategies including vaccination.

Out of the 370 participants, 73.5% were female and the mean age for all participants was 36.4 years (SD = 8.4). On average females were older than males (36.9 years compared to 34.6 years) respectively. Female HCW on average had spent about 14 years in service compared to about 8 years for the males. About 56.5% of HCW were working in a surgical department, 38.4% in a medical/pediatric department and only about 5.1% were working in laboratories.

This study shows that hepatitis B virus sero-markers are prevalent among health care workers in a Ugandan tertiary hospital. The prevalence of current infection was 8.1% and that for life time exposure was 48.1%. Findings from a similar study conducted among health care workers in Uganda found a comparable prevalence of 9.0% for current infection, however that for life time exposure to hepatitis B virus infection was much higher at 60.1% [24]. Our results show marked variations in prevalence of Hepatitis B sero-markers by type of health care worker, department, and religion. Similar observations have been reported in other studies with laboratory technicians, dentists and nurses being disproportionately affected [12, 27]. The variations among the different cadres of HCW might be a reflection of the different levels of risk of exposure to a hazardous work environment the different categories of health care workers operate in. However, other risks such as sexual activity that were not explored in this study could explain the variations. Differentials in knowledge about the dangers of hepatitis B virus infection and the available prevention strategies might also partly explain the observed differences in prevalence. Indeed our results show that individuals with no training in infection prevention had a higher risk of life time exposure to hepatitis B virus infection. Nationally, the prevalence of HBsAg and anti-HBc shows great variation along demographic lines such as ethnicity, region, age, religion, among others which may influence the distribution of infection seen among the HCW. For example a population based survey revealed that the prevalence of anti-HBc among the Banyankole tribe in the western part of the country was 28.3% while that of Karimojongs in the north eastern part of the country was 93.2%. In the same study, the prevalence of HBsAg among Catholics was 11.5% compared to 7.1% among Moslems and 2.6% among other Christians (other than Catholics and Protestants) [6].

Exposure to potentially infected patient fluids is quite high. We found a considerably high proportion of individuals who had had either a needle stick injury, cut or other form of exposure and yet only 6.2% were vaccinated with just about a third of these getting the recommended three doses. The incomplete vaccination schedules might explain the observation that while 6.2% of all participants reported that they had ever been vaccinated, only 3% of participants were immune as a result of vaccination. Although several studies including this one have shown that individuals from certain departments tend to have a higher prevalence of hepatitis B, our results further show that exposure to potentially infectious body fluids particularly through needle stick injuries is high across the board. Given the high efficiency of transmission of hepatitis B virus and the frequent use of injections, most health care workers even those in non-surgical departments are at a considerably high risk.

Although 48.1% of all participants had ever been exposed to hepatitis B virus infection and some of them got immune after the infection, a sizeable 48.9% remained susceptible to infection and could potentially benefit from vaccination. The 6.2% vaccination coverage reported in this study is very low compared to other developing countries like Pakistan with vaccination coverage of over 80% [28]. Vaccination of health care workers against Hepatitis B virus in Uganda is not mandatory and there is no formal framework for delivering vaccines to HCW. Results show that a large proportion of HCW appreciate the need to be vaccinated, with more than 95% indicating that they were willing to be vaccinated if the vaccine was provided free of charge. The lack of policy and a formal delivery system targeting HCW is a key challenge.

There is a complex multiplicity of risks of exposure and it is difficult to tease out the biggest contributors to infection. For example whereas the laboratory technician category had one of the highest proportion of HCW who thought that their own risk of infection was high, they had one of the lowest rates of consistent use of gloves. Doctors who were on average at high risk of getting a needle stick injury (NSI) or cut were more likely to be vaccinated potentially canceling out the excess risk. Also the risk of childhood and sexually acquired infections was not accounted for in this study thus making attribution of excess risk to occupational exposure a bit challenging. After controlling for other variables, longer duration in service remained significantly associated with a lower risk of current infection. This finding is at variance with what has been reported in other studies where prevalence of HBsAg was highest amongst the longest serving participants [24, 29]. Being a laboratory technician or a nursing assistant was independently associated with a higher risk of current hepatitis B virus infection. This finding is in line with other studies [12]. Nursing assistants are at the bottom of the nursing hierarchy and are also closer to patients on a routine basis. Unlike their senior counterparts, they receive no formal training but rather learn on the job. These differences might explain the higher risk of infection in this group. Lack of in-service training on infection prevention was also associated with increased risk of life time exposure to infection. Several other factors such as history of blood transfusion, needle stick injuries, and vaccination status that have been reported in other studies to be associated with an increased risk were found not to be significantly associated with risk of hepatitis B virus infection in this study. With the advent of rigorous screening of blood for transfusion in Uganda it is likely that the risk of infection through transfusion is very minimal. On the other hand, needle stick injures and cuts are so prevalent as shown in this and other studies[14] that most health care workers have had an experience at least once during service.

The stratified random sampling approach used in this study meant that participation was proportionate to population size in a given stratum (HCW category). Some categories of HCW generally have few staff such as the dental and laboratory categories. Because of this the numbers in some cells were too small to allow for stable estimates to be derived (wide confidence intervals). In future similar studies should consider the need to oversample in underrepresented subgroups that have been reported to have a high prevalence. Additionally other factors known to contribute to the risk of infection such as sexual behavior were not assessed. This is one area that might need consideration while designing data collection tools for similar studies. A set of questions akin to those administered to HIV/AIDS sexual behavior studies could be considered. Recall bias is a potential source of bias in this study as respondents may not be able to accurately remember events that happened long time ago. Lastly these results might have limited generalizibility given that participants were drawn from a single large teaching hospital. The situation in smaller health care facilities might be different.

The prevalence of current hepatitis B virus infection and life time exposure to hepatitis B virus infection among health care workers was high. Exposure to potentially infectious body fluids was also high and yet only a small percentage of HCW are vaccinated against hepatitis B virus infection. Considering the risk of liver cirrhosis, hepatocellular carcinoma and transmission of HBV to patients, there is need to focus efforts on mitigating transmission through improving the work place environment and making use of the available vaccine by vaccinating all health care workers who are susceptible. Also given that the government of Uganda recognized the importance of hepatitis B virus infections among children and introduced vaccination in the childhood schedule, subgroups of adults at high risk such as HCW should be considered as a matter of policy. For example vaccination against hepatitis B virus infection could be made mandatory for preclinical medical and nursing students. The Ministry of Health could consider offering subsidized or free Hepatitis B vaccination to HCW. In addition education on infection control and other strategies for infection control need to be strengthened.