An estimated 33.2 million people are infected with the human immunodeficiency virus (HIV) worldwide [1]. It was estimated that more than 60% of the infected population are in sub-Saharan Africa [2]. In Nigeria, HIV prevalence among the general population is 4.1% with about 3.1 million people living with HIV and about 300,000 new infections occurring annually [3].
Similarly, infection with hepatitis B virus (HBV) is a serious public health problem in the country [4,5]. Nigeria has remained a hyperendemic area of hepatitis B virus infection, with an estimated 12% of the total population being chronic carriers in spite of the availability of a safe and effective vaccine [6]. In Nigeria, universal childhood vaccination against the HBV started less than fifteen years ago and its coverage has increased over the years.
HIV/HBV co-infection is a growing concern because apart from increasing the toxicity to antiretroviral medications, [7] coinfected patients have higher levels of HBV replication, lower rates of spontaneous resolution of the HBV infection, and higher risk of reactivation of previous infections, and thus, are at an increased risk of developing cirrhosis of the liver [8].
Apart from their ability to integrate within the host genome, a process which is obligatory for the life cycle of HIV but not for HBV [9], HBV and HIV have similar properties such as transmission using a reverse transcriptase enzyme in replication, tendency to develop chronic infections, and an immense capacity of mutation in their genome, causing rapid emergence of mutant strains, some of which are resistant to widely used anti-viral agents [9]. Consequently, knowledge of country-by-country prevalence of HBV/HIV co-infection will may impact positively on prevention and treatment strategy of HBV /HIV co-infection in the country of interest.
The impact of co-infection is particularly important in places with widespread use of antiretroviral therapy. As the use of ART increasingly becomes prevalent in certain regions of the world with high HBV endemicity and as long term survival increases, It is likely that liver disorder following chronic HBV in HIV-infected population may emerge as a greater public health problem than before [10]. This potential problem was suggested in a meta-analysis that reported on 12382 patients living in Europe which found a significant 36% excess risk of all-cause mortality attributed to the effect of HBV co-infection in HIV patients (pooled effect estimate, 1.36; 95% CI, 1.12-1.64) [11]. Furthermore, establishing a reliable estimate of HIV/HBV burden will facilitate provision of ART regimens that are effective on both HIV and HBV infections such as Tenofovir and either Lamivudine or Emtricitabine ART two drug backbone.