HIV remains a major global public health issue, having caused the deaths of some 44.1 million people. Transmission continues in all countries worldwide. It is estimated that approximately 40.8 million people were living with HIV at the end of 2024, 65% of them in the WHO African Region [1]. Several years after its discovery, the Human Immunodeficiency Virus (HIV) remains one of the leading causes of death worldwide, with Sub-Saharan Africa paying the heaviest price [2].

Hepatitis B is a major public health issue [3]. The WHO estimates that 254 million people were living with chronic hepatitis B in 2022, with 1.2 million new infections each year. Approximately 1% of people living with HBV (2.7 million) are also infected with HIV. Conversely, the global prevalence of HBV infection among people infected with HIV is 7.4% [3].

The World Health Organization (WHO) classifies Chad as a region with high HBV endemicity, corresponding to an HBsAg seroprevalence of 8% [4].

Co-infection with Hepatitis B Virus (HBV) and Human Immunodeficiency Virus (HIV) is a major public health concern worldwide, particularly in sub-Saharan Africa [5].

The hepatitis B virus is transmitted in the same ways as HIV/AIDS. The clinical manifestations of HIV-HBV co-infection are indistinguishable from those of chronic hepatitis [6]. HBV vaccination should be offered to HIV-positive patients with no markers or isolated anti-HBc antibodies [6].

In Cameroon, the prevalence of HIV-HBV co-infection was 35.6% [7]. In Bangui, the prevalence of HIV-HBV co-infection was 11.7% [8]. In Senegal, 6.5% of people are co-infected with HIV and HBV [9]. The management of HIV infection must take into account the possibility of HBV infection [8].

HIV infection alters the natural history of HBV and worsens the prognosis for patients with chronic hepatitis B. It is associated with an increased risk of acute hepatitis B becoming chronic, thereby accelerating the progression of lesions such as fibrosis and the risk of developing complications such as cirrhosis and hepatocellular carcinoma [10].

In our context, surveys on HIV/HBV co-infection and vaccination status are not sufficiently conducted among people who have not received antiretroviral treatment. The objective of our study is, therefore, to determine the prevalence and vaccination status among patients co-infected with HIV/HBV in N’Djamena, Chad.

During the study period, we followed 2210 individuals who came for voluntary HIV and hepatitis B screening at the study sites, patients who had not received antiretroviral treatment, of whom 1770 were HIV-negative 80.1%; 432 were HIV-1 positive representing a HIV-1 infection rate of 19.5%; HIV-2 0.1% and HIV1-2 0.3% (Table 1).

The number of participants was estimated at 2210 patients, of whom 133 were co-infected with HIV/HBV, representing a prevalence of HIV/HBV co-infection of 6% (Figure 1).

The prevalence of HIV/HBeAg was 1% (n = 22), while that of HIV/anti-HBcAb was 2.4% (n = 54), HIV/anti-HBs antibodies was 100% negative (n= 133). The results of this study show that the prevalence of HIV/HBsAg was higher among females (9.40%) than among males (3.80%), with a sex ratio (M/F) of 0.60 (Figure 2).

Table 1. Distribution of frequency and percentage of status and type of HIV.

Figure 1. Frequency and percentage for HIV/HBsAg.

Figure 2. HIV/HBsAg prevalence by sex.

We observe that males were the most represented in the total sample with 1,329 (60.1%) participants, giving a sex ratio (M/F) of 1.50. The most represented age group was patients aged 25 to 35 years, with 36.8% of the sample, followed by those aged 18 to 25 years, with 30.0%, with extremes ranging from 18 to 70 years old (Table 2).

We note that married individuals constituted the dominant group with 44.8% of respondents, followed by single individuals with 37.3% (Table 2 and Figure 3).

Other professions accounted for 20.7%, and civil servants accounted for 16%. In terms of educational attainment, higher education accounted for 40.9%, followed by secondary education at 32.5% (Table 2). Hepatitis B vaccination: during our study, none of the patients had been vaccinated against HBV, representing a prevalence of 100% unvaccinated against HBV (Table 2).

Figure 3. HIV*Status married.

Table 2. Distribution of sociodemographic and vaccination status.

The prevalence of HIV/HBV co-infection in this study was found to be 6%; this prevalence is close to that reported by Manga N. M. et al., in Senegal, which was 6.5% [9]; Hamidine I. et al., in Niger (Zinder), 6.45% [10]; and in Togo by M. R. TOGAN et al., 6.5% [13]. On the other hand, Zezerti et al. found a prevalence of HIV/HBV of 4.17% in N’Djamena [14].

This high or moderate prevalence could be explained, on the one hand, by the absence of a vaccination policy for adults, unlike children who receive the vaccine as part of the expanded program on immunization, and the lack of mass screening campaigns. Added to this are other risk factors for co-infection, such as having multiple sexual partners and engaging in unprotected sex.

Higher prevalences of HIV/HBV co-infection have been reported in China by Y. X. Y. A. N. et al., 12.49% for HIV/HBsAg [15]; in Wilson et al., 23.7% [16]; in Benin (Parakou) by Dovonou et al., 16.9% [17]; in N’Djamena, Chad by Bessimbaye et al., 16.1% [18]; in Burkina Faso by ILBOUDO, 15.3% [19]. The difference between these prevalence rates and those in our study is related to the methodological approach (often a retrospective study; the inclusion criterion of patients already infected with HIV and receiving antiretroviral treatment; and also the study period, which has an influence).

The average age of our patients was 35, ranging from 18 to 70; this can be explained by the fact that HIV infections and other viruses with the same modes of transmission are frequently observed in young adults who are physically and sexually active.

For HIV status and type, we obtained an HIV-1 infection rate of 19.5%; HIV-2 of 0.1%, and HIV1-2 of 0.3%. This result is consistent with those found by Bessimbaye et al. in Chad, where 99.98% were HIV-1 positive compared to 0.2% HIV-2 positive, confirming that HIV-1 is the predominant type in Central Africa in general and Chad in particular [18].

In our study, HIV/HBV co-infection was predominantly found in women, 9.40%, with a sex ratio (M/F) of 0.60. The predominance of women is consistent with data in the literature; in Cameroon, the predominance is female [7]; in Sénégal, Ndiaye M and al., found that women predominated, accounting for 78.13% [20]; in Libreville, Magalie and al., found that women predominated with a sex ratio of 0.7 [21]. Several factors explain women’s vulnerability to HIV in our context, including biological vulnerability. Women are 2 to 4 times more at risk of HIV during sexual intercourse than men, as the fragility of the vaginal wall offers multiple routes of transmission for HIV and also increases the risk through IST, according to the WHO [22].

Among our patients, married individuals accounted for 44.8%, a result similar to those found by M. A. Bolti et al., with 46.6% married [22]; Boateng et al. found that a majority, 49.5% of the subjects were married [23]. Married individuals are most at risk. This increase among married individuals can be explained by the refusal to disclose HIV status to a spouse for fear of stigmatization and breakup of the couple [22].

In our study, other professional statuses accounted for 20.7%, while civil servants accounted for 16.0%. Our results were similar to those reported by Hamidine I. et al., in Niger, where other professions accounted for 17.58% and civil servants for 14.29% [10]. Other professions, homemakers, and civil servants were vulnerable because they were working.

Vaccination status: We found that none of the patients had been vaccinated against HBV. Our results differ from those found in Lomé (Togo) by TAKASSI O. E. et al., testing for total anti-HBs and anti-HBc antibodies in HBsAg-negative patients showed that only 0.4% of patients had been vaccinated against HBV [24]. This could be explained by the fact that our methodologies differ in that we were unable to perform anti-HBs antibody serology in HBsAg-negative patients. The prevalence of HIV/HBeAg is 1.0%, while that of HIV/anti-HBc antibodies is 2.4%. We did not find any data on viral markers (HBeAg and anti-HBc antibodies) for hepatitis B in the literature reported in our study.

Patients co-infected with HIV/HBV were placed on triple antiretroviral therapy based on Tenofovir + Lamivudine + Dolutegravir (TLD) by doctors at treatment centers in accordance with the treatment regimen recommended by the Ministry of Public Health and Prevention. In cases of HIV/HBV co-infection in adults, adolescents, and children aged 3 years or older co-infected with HIV and HBV, the fixed-dose combination of Tenofovir + Lamivudine + Dolutegravir is the preferred option for starting triple antiretroviral therapy [4].

At the end of this study, it appears that the prevalence of HIV/HBV coinfection was 6% in N’Djamena, with a predominance among women. The application of the current World Health Organization recommendations on screening and management of HIV/HBV coinfection will reduce morbidity and mortality.

Prevention through vaccination against hepatitis B virus in at-risk individuals remains the best strategy for reducing the prevalence of hepatitis B in the general population, and particularly among HIV-infected individuals. Large-scale national surveys are needed to determine the extent of HIV/HBV coinfection.

All authors contributed to data acquisition, analysis, and interpretation; writing of the paper; critical review of its intellectual content; and final approval of the version to be published. All authors contributed to the conduct of this work. All authors also declare that they have read and approved the final version of the manuscript.

The study was conducted in strict compliance with confidentiality requirements, and anonymity was ensured through the use of patient registration numbers. We obtained ethical clearance from the National Bioethics Committee of Chad under number N°056/MESRS/SE/SG/CBNT/SG/2025. Research authorizations were obtained from the various health centers in N’Djamena. All participants agreed and signed the informed consent form.

1) To all study participants. 2) To the Ministry of Public Health and Prevention, to the sectoral program for the fight against AIDS, hepatitis, and sexually transmitted infections (PSLSH/IST). 3) To the management and staff of the Psycho-Socio-Medical Support Center (APMS), CHU-ATC, and CHU-RN.