Tuberculosis is an infectious disease caused by bacteria belonging to the genus Mycobacterium and species of the Mycobacterium tuberculosis complex. Pulmonary involvement is common in humans and animals, with the disease spreading through the air. This disease remains a major cause of morbidity and mortality, with 1.6 million deaths among the 10 million people with tuberculosis worldwide in 2022 (according to the World Health Organization). This reservoir of infection produces approximately 8 million new cases each year, with one new case occurring every second [1]. The infection affects more than one-third of the world’s population, and nearly 2 million people die from the disease each year. All age groups are at risk, but 75% of cases occur in people aged 15 to 45, who represent the most economically productive group. The human immunodeficiency virus (HIV) pandemic has led to a resurgence of tuberculosis in many countries. The situation has worsened since the 1990s with the emergence of multidrug-resistant (MDR) strains and XDR (extensively or extremely drug-resistant tuberculosis) forms. Microscope-positive pulmonary tuberculosis (MPTB) is the most common form and the only contagious form. Incidence and prevalence are the two morbidity indicators that provide the best assessment of the burden of a disease. The risk of tuberculosis transmission is determined by the presence of new cases or incident cases. In Africa, tuberculosis has always been a scourge despite the efforts of control programs. In most African countries, the annual incidence rate varies between 100 and 500 cases per 100,000 inhabitants [2]-[5]. The poor socioeconomic conditions of African populations contribute to the maintenance of these very high incidence rates [6]. In the Central African Republic (CAR), the fight against tuberculosis is implemented by the National Tuberculosis Control Program (PNLT). The prevalence of MDR-TB in the CAR has already been the subject of previous studies [7][8]. The incidence of tuberculosis already documented among people living with HIV in the CAR dates back to 2014 [9]. The same is true for the molecular diagnosis of MDR-TB with reported cases of resistance [10]-[12]. These studies concern almost exclusively the city of Bangui. The CAR has a total of thirty-five health districts (HDs) spread across seven health regions. This study aims to identify new cases of tuberculosis through an incidence study based on molecular screening carried out in thirty-two health districts across the country.

Biological diagnosis of tuberculosis, chemotherapy, and vaccination for infants are free in the CAR, but the disease is far from eradicated. This can be explained by certain factors such as antibiotic resistance, poor public health policy (vaccination, communication), and management by the PNLT. The problem of tuberculosis management by the program in charge and poor public health policy has already been raised by some authors [7] in the Central African Republic. During the first half of 2025, the 32 health districts out of the 35 districts in the seven health regions of the CAR recorded 12,112 samples from patients suspected of having tuberculosis. The age of patients at screening ranged from 4 months to 100 years, with a median age of 35 years (standard deviation ± 18 years). The incidence of tuberculosis reported in our study was 45.50 per 100,000 person-semester. Studies conducted elsewhere have reported higher incidence rates than ours. These are studies conducted in Algeria, which reported an average incidence of 56.02 per 100,000 inhabitants and an average incidence of 63.81 cases per 100,000 inhabitants for all forms of tuberculosis combined [13][14]. The discrepancy between these incidence data can be explained by the sample size. Our study covered data from one semester, whereas the two studies conducted in Algeria covered a period of five years (2015 to 2020). The incidence of tuberculosis is not negligible. However, it should also be noted that tuberculosis can affect all age groups. The Central African population is characterized by its youth in demographic terms. Taking into account the size of the age groups screened, these districts recorded 2142 cases of tuberculosis among people aged 15 to 49, with a proportion of 17.68%, which is the highest among the age groups. This age group accounted for 74.85% of detected tuberculosis cases. In the CAR, the 15 - 45 age group represents the most productive age group in the population. There is therefore a risk of economic and social loss. The predominance of our data among patients aged 15 to 49 is consistent with that observed among people aged 15 to 45 in Algeria (60.39%) and in developing countries, where it accounts for 75% of cases [14][15]. The highest incidence of tuberculosis is among people aged 50 and over (323.50/100,000 person-semesters). This is explained by the low denominator, which is the at-risk population for this age group. In this study, the incidence of tuberculosis increases with age. This incidence is consistent with that of a study conducted in Europe [16]. The risk of developing tuberculosis increases with age and is most often the result of endogenous reactivation of dormant bacilli, which become pathogenic when the body is weakened either by age or by immunosuppression. Incident cases of tuberculosis were more common in men. This observation is consistent with studies conducted in the Central African Republic, Mali, and Chad [7][17][18]. This predominance of tuberculosis in men could be explained by exposure to risk factors such as a history of smoking, occupational respiratory diseases, alcoholism, and drug use [19]. In contrast, some previous studies have shown a high proportion of tuberculosis in women, particularly in Algeria, with 67.84% of cases and 44.81 cases per 100,000 inhabitants [14][20]. Malnutrition and biological changes that can disrupt the immune system, as well as acute or chronic diseases, are factors that may explain the occurrence of tuberculosis in women [21]. Incidental cases of pulmonary tuberculosis are the main source of infection and, consequently, transmission of the disease. The pulmonary form was predominant in our study (96.43%). This is consistent with studies conducted in the Central African Republic [9]. In contrast, the predominance of extrapulmonary forms has been described by some authors in Algeria and Korea [20][22]. Pulmonary tuberculosis can be attributed to many factors. These include poverty, sociodemographic characteristics (age, gender, place of residence) related to the disease, personal data (smoking, alcohol consumption), vaccination coverage, availability of anti-tuberculosis drugs, the concept of contagion, and the policy of the national tuberculosis control program. The predominance of pulmonary tuberculosis over extrapulmonary tuberculosis can be explained by the fact that extrapulmonary tuberculosis is very difficult to diagnose using microscopy because it is paucibacillary.

Fluids and biopsies from internal sites in the body are very low in bacilli because microorganisms cannot multiply easily in deep organs due to a lack of oxygen. The concentration of mycobacteria is minimal in samples [21]. Mycobacterium tuberculosis has a high capacity to infect several tissues in the body. This has led to the emergence of new forms of tuberculosis that are difficult to diagnose and known as extrapulmonary tuberculosis [23]. The task has been made easier today with the advent of GeneXpert, which, unlike microscopy, detects tuberculosis regardless of its location. In addition, tuberculosis can be detected in patients with a low bacterial load (very low and low), which accounts for 26.72% of cases. The present study did not report any clear variation between months. In the Central African Republic, the first quarter of the year corresponds to the dry season. However, some studies have reported that the incidence of tuberculosis is seasonal and that the disease predominates in spring and summer [14]. Certain factors such as sun exposure, indoor activity, and seasonal changes in immune function promote the emergence of tuberculosis [21]. Tuberculosis transmission is more likely in winter due to the decrease in natural ultraviolet light. Depending on the place of residence, the number of tuberculosis cases, and even the incidence of the disease, were higher among patients from the Bangui 3 district. This district is one of the three districts of the city of Bangui, which is Health Region No. 7. It ranks fifth among the thirty-two districts in the study in terms of its at-risk population, but with a negligible difference compared to the top four districts. The predominance of tuberculosis cases in this district can be explained by several factors, such as the urban environment with a high population density, the availability of qualified personnel (clinicians and laboratory technicians), and adequate technical facilities for laboratory screening. Unlike the data from Bangui 3 District, which is located in an urban area, the districts often face certain difficulties in screening for tuberculosis. Sometimes tuberculosis is diagnosed at the health facility by a clinician or in a local laboratory, which often has limited technical facilities and qualified personnel. Patients suspected of having pulmonary tuberculosis are referred to the district hospital laboratory. The distance to the district hospital is a handicap for the diagnosis and treatment of tuberculosis in rural areas of the CAR.

Admittedly, this study has its limitations. HIV data are not documented for patients who test positive for tuberculosis. This contravenes the recommendations of the National Tuberculosis Control Program (PNLT) in the CAR, which stipulate that all patients who test positive for tuberculosis must be screened for HIV. This would ensure better management of tuberculosis/HIV co-infection. Added to this are socio-economic status and malnutrition due to lack of questioning.

Tuberculosis remains a major public health problem in CAR today, due to its morbidity and mortality rates. Given the results obtained in this study, the incidence of tuberculosis remains higher in CAR. The overall incidence was 45.50 per 100,000 person-months. Incidental cases were more common among young patients, males, and in health region 7. Pulmonary tuberculosis was the most common form. In this study, the incidence of extrapulmonary tuberculosis was lower than that of pulmonary tuberculosis, because Mycobacteria are paucibacillary and rare. GeneXpert has greatly contributed to tuberculosis screening by identifying cases of tuberculosis with rare bacilli, different locations of the disease, and finally, the detection of resistance to anti-tuberculosis drugs. This test has aided diagnosis in various health districts in the CAR. It would be better for the NLT to revitalize HIV screening among patients who test positive for tuberculosis in order to ensure better management of the disease and review the control strategy, with an emphasis on staff training and public awareness.