Introduction

Leprosy, caused by Mycobacterium leprae, is one of the oldest known infectious diseases in human history, which spread throughout the world following human migration paths from the African continent to Asia and Europe, where factors such as wars, anti- hygienic conditions, social and health inequality created conditions for its propagation since prehistoric times, and existing health disparities contributed to uneven morbidity and mortality, before their gradual decline after the Middle Ages due to the emergence of other worse pandemics [1,2].

The relationship between leprosy and poverty, lack of basic sanitation, and fragility of health and education services, especially in developing countries, contribute as a threat to the eradication of the disease, since leprosy, is characterized by an infectious, chronic, endemic disease, of compulsory notification, neglected and considered a serious public health problem [3].

In 2016, the World Health Organization (WHO) prepared a document to describe the global strategy adopted to completely eradicate leprosy worldwide, where it emphasized the importance of integral political and economic coordination and an effort against the cases of leprosy still present in the world, in order to prevent related disabilities and other complications [4]. However, in 2018, 208, 619 new cases of leprosy were diagnosed in 159 countries, which highlights the need to replan strategies linked to public health [5].

According to the Angolan health authorities, about 1,887 cases of leprosy have been treated since 2005, when Angola reached the goal of eliminating the disease, according to data from the WHO, in turn, in 2022, the province of Luanda recorded around 184 new cases of leprosy in 2022 [6].

The ABO system is the most crucial blood group polymorphism related to compatibility and has been linked to infections such as - E. coli, P.vivax, P.falciparum, Candida, H.pylori, HIV, V.cholerae, Parvovirus B19 and Influenza Viruses [7] and other diseases such as cancer, cardiovascular diseases, hematological disorders, cognitive disorders, circulatory diseases, metabolic diseases and malaria [8,9].

Individuals of blood group AB were considered susceptible to cognitive impairment, disorders such as hypertension, obesity, dyslipidemia, cardiovascular disease and diabetes, smallpox and E. coli, and salmonella infection; group O has an increased incidence of cholera, plague, tuberculosis infections, and mumps; blood group A is related to increased incidence of smallpox and Pseudomonas aeruginosa; blood type B is also associated with an increased incidence of gonorrhea, tuberculosis, and Streptococcus pneumoniae, E. coli, and salmonella infections [10].

Recent studies carried out by our research team in Angola, to assess the frequency of blood groups in patients with Arterial Hypertension, showed that the most frequent blood group was group B 36.4% (36/99), in the study to assess the frequency of groups in patients with chronic kidney disease, most individuals belonged to group O 56.4% (79/140) and in patients with Nephrotic Syndrome (NS) and Sickle Cell Anemia (SC), most of the population belonged to the group ORh+, followed by patients in the ABRh+ group [11-13].

Although several studies demonstrate the association between blood groups (ABO) and infectious diseases, no studies were found that correlate leprosy disease with the classification of blood groups. From this perspective, the present study aimed to evaluate the frequency of blood groups (ABO/Rh) and the sociodemographic and clinical profile of patients with leprosy treated at the Anti-Tuberculosis and Leprosy Dispensary in Luanda, the capital city of Angola.

Methodology

Study design

This was an analytical, prospective study, with a quantitative approach, where the blood group (ABO System) and Rhesus factor were determined in patients with leprosy (leprosy) treated at the Anti-Tuberculosis and Leprosy Dispensary of Luanda in the second half of 2021. In the database, the population consisted of 250 patients, from which a sample of 150 patients with leprosy was extracted, regardless of sex and age.

Variables studied

Variables such as ABO/Rh blood group, age, sex, education, place of residence, type of infection, number of lesions, methods used in diagnosis, associated diseases, complications result of the erythrocyte, leukocyte, and platelet count were obtained.

Analysis of blood groups

A blood sample estimated at 2 mL was collected for each patient by the venipuncture technique and the samples were placed in test tubes containing ethylenediaminetetraacetic acid (EDTA). The samples were placed in three wells and the latter was associated with anti-A, Anti-B, and Anti-D reagents (Immucor, Portugal). Blood group determination was performed using the microplate technique according to the manufacturer's instructions, which is an agglutination test between the patient's serum and the anti-A, Anti-B, and Anti-D reagents from each well for phenotypic identification of the blood. groups (ABO and Rh).

Laboratory procedure

The erythrogram and white blood cell data were evaluated on the admission of patients before starting antimalarial treatment. For the erythrogram data, hemoglobin (Hb), red blood cell count (RBCs), Red Cell Distribution Width (RDW), hematocrit (Hct), mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) were evaluated. For the Leukogram data, the lymphocytes, platelets, neutrophils, and leukocytes counts were evaluated [22]. The study did not include mean corpuscular hemoglobin (MCH), monocyte count, eosinophil count, neutrophil-to-lymphocyte ratio (NLR), and monocyte-to-lymphocyte ratio (MLR) due to the devices that had some problems in reading these exams in some of the patients, as we did not obtain data from all patients included in the study, these data were not analyzed in the study because they were not complete for all patients. In cases where the reference values of blood cell count components were different between men and women, the reference values were adjusted for the whole group based on the minimum value for women and the maximum value for men, in addition, it was performed adjustment according to the references according to the specific characteristics of the Angolan population, as can be seen in the presentation of the results.

Statistical analysis

The data obtained in this study were analyzed using SPSS v20 (IBM SPSS Statistics, USA). Absolute and relative frequencies were determined in the descriptive analysis. Normally data distribution was expressed as mean and Standard Deviation (SD). Chi-square (X2) test was used to assess the relationship between categorical variables. All reported p-values are two-tailed and deemed significant when p<0.05.

Results

Socio-demographic data

The sociodemographic data (Table 1) found in patients with leprosy show that the majority of the population consisted of young people aged between 21 and 40 years, representing about 55.9% of the entire population studied; with a predominance of males (63.7%); except for illiterate people, who represented only 7.8% of individuals affected by leprosy, as the level of education increases, the incidence of cases decreases; Regarding housing, it was found that the majority resided in the municipality of Luanda, followed by Viana, and Belas. Of the 102 patients included in the study, most belonged to the ORh(+) group, which represented 51.9% of the entire population studied, followed by the BRh+(27.4%) and ARh+(18.6%) groups. Only one ABRh+ and BRh- individual was found in the present study. In all the variables of the ABO system studied, most individuals were in the ORh+ group. There was no significant relationship between sociodemographic data and blood groups of patients with leprosy (p>0.05).

Table 1: Sociodemographic data and blood groups of patients with leprosy.

When evaluating the blood groups in relation to the clinical condition and complications resulting from leprosy (Table 2), we found that most patients were classified as new cases of the disease (66.7%), however, the lowest mean age (29 .8 years, SD=10.3) was found in patients who were considered to be reentry cases. It was found that most patients included in the study had multibacillary infections (93.1%) and were mostly diagnosed with smear microscopy (75.5%). In the evaluation of pre-existing diseases to leprosy infection, we found that most individuals had no previous disease (79.4%), however, diseases such as Arterial Hypertension, Hepatitis B, and Tuberculosis were cited as a condition prior to leprosy in some patients, where he noticed that individuals with pre-existing diseases had a higher average age than individuals without any other pathology. As for the complications resulting from leprosy, we noticed that ulcers (11.8%), visual problems (8.8%), mutilations, and claws (3.9%) were the complications most cited by patients. With the exception of the clinical diagnosis, Hypertension and mutilations, where there was a majority of individuals in the ARh+ group, in all other clinical situations and complications, it was found that the individuals in the ORh+ group were the most affected. There was a significant relationship between disease classification by the number of lesions as well as diseases associated with blood groups (p<0.05).

Table 2: Blood groups and clinical condition and complications in patients with leprosy.

In the evaluation of the hemogram (Table 3) in patients with leprosy according to blood groups, we noticed that in the erythrogram only the mean number of erythrocytes (RBC) was normal in all groups. However, ABRh+ patients had mean Hemoglobin (HBG), Hematocrit (HCT), Mean Corpuscular Volume (MCV), and Mean Corpuscular Hemoglobin (MCM) slightly below the reference values and Red Blood Cell Distribution Range (RDW) slightly above the reference values. Individuals in the ARh+ group presented the mean Hemoglobin (HBG) and Hematocrit (HCT) values slightly below the reference values. Individuals from the BRh- group presented the average Mean Corpuscular Volume (MCV), Mean Corpuscular Hemoglobin (MCH), and Mean Corpuscular Hemoglobin Concentration (MCHC) slightly below the reference values.

In the leukogram evaluation, individuals of the ABRh+ group presented the mean of Leukocytes (WCB) and Lymphocytes (LYM) slightly below the reference values, while the mean of Monocytes (MONO) was slightly increased. Individuals in the BRh- group presented mean Neutrophils (NEUT) and Eosinophils (EOS) slightly below the reference values, while the mean Lymphocytes (LYM) were slightly increased.

In the plateletogram, only individuals in the ABRh+ group had a mean Platelet (PLT) far below the references, the other groups had a normal mean Platelet value. All patient groups, with the exception of the BRh+ group, had a decreased mean platelet volume (MPV) value, which indicates that the production of platelets in the bone marrow is slightly below the reference values.

Table 3: Blood groups and changes in the blood count of patients with leprosy.

Discussion

Based on the absolute number of cases analyzed in the present study, it was clear that the ORh+ group prevails among individuals. This prevalence among the ABO System (ORh+) was also found in a study with patients undergoing hemodialysis [14], in nephrotic syndrome and sickle cell anemia [13]. Although we have not found recent studies on the correlation between blood groups (ABO/Rh) and leprosy, several studies point to the correlation between ABO/Rh blood groups and infectious clinical conditions, such as its association with infection by the hepatitis B virus in China [15], were found that among 3,827,125 participants, the proportion of participants belonged to blood group A (30.54%), followed by group O (30.37%), B (29.42%) and AB (9.66%) and a total of 38,907 (1.02%) were Rh-D negative.

In table 1, we found a prevalence in individuals under 50 years of age, male, regardless of schooling and region of residence. These data are similar to a literature review study on leprosy in several countries, where they found that the mean age was 46.1 years, with the lowest ages observed in the cases of Australia, Germany, Libya, and Malta (average age below 40 years) and that nearly two-thirds of all cases were male (65.2%), with only Taiwan and Thailand recording a female percentage above 50% [16]. A study with 801 leprosy cases diagnosed in Morocco between 2000 and 2017, found 48 children diagnosed with leprosy and most cases (72.4%) resided in rural areas of the country [10].

 Data related to the place of residence and schooling (Table 1) are similar to those were identified that individuals living in the most impoverished regions of the country had a risk of leprosy incidence of five to eight times greater than those other individuals, in addition to the fact that reduced levels of income, education, and factors that reflect unfavorable living conditions are associated with up to a two-fold increase in the incidence of leprosy [17].

It was found in the present study that most leprosy patients were recent cases of the disease (Table 2), as it is similar to those reported by the Health Organization in the Dominican Republic of Congo, which is one of the 23 priority countries WHO's global efforts to combat leprosy, 3,032 new leprosy cases were reported in 2019, which assumes that given the recent political and economic instability in the country, the transmission of leprosy and other neglected tropical diseases largely reflects the importance of socioeconomic status as a predictive factor [18]. Regarding the classification, table 2 shows that more than 90% of the cases were Multibacillary, which is similar to the findings when of the 3,950 records of leprosy cases collected in 22 low-endemic countries, 48.3% were suspected of being imported and most cases were multibacillary (64.4%) and confirmed regularly by skin biopsy, with 122 cases of suspected recurrence of previous treatment for leprosy [16].

In the present study, it was found that only a small number of individuals with leprosy had some pre-existing disease (Table 2), data that are similar to those presented in the review where the pathological history was mentioned by 14 (77.8%) patients; three (7.1%) reported HIV/AIDS, three (16.6%) tuberculosis, seven (38.9%) participants reported vaccination with Bacillus Calmette-Guérin and all cases had multibacillary leprosy, these co-infections in leprosy can modify host immunity, so as to increase inflammation and tissue damage, leading to reactions and neuritis, or depress defense mechanisms, resulting in increased bacterial load or relapses [19].

We also see in table 2 that about 26% of individuals with leprosy developed complications resulting from the disease, as described in a study, that individuals with leprosy develop dermatoneurological complications, causing cranial nerve paralysis, along with corneal insensitivity and lagophthalmos, which can lead to trauma, infection, as well as corneal ulcerations and opacities, in addition to blindness in third world countries is correlated with the number of positive leprosy cases [19].

Blood count data were altered (Table 3) for some individuals depending on the blood group, this data differs from the study, which revealed a marked decrease in hemoglobin concentration, platelet count, mean platelet volume, hematocrit, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration [20].

Conclusion

Our results indicate that leprosy is still a public health problem in Angola. The ORh+ group is the most frequent among patients with leprosy, followed by the BRh+ and ARh+ groups. Men are the most affected by the disease and the most common diagnostic method is smear microscopy, where most patients are multibacillary and present complications in the peripheral nervous system. The patients do not seem to be the ones with the most changes in the blood count.

Ethical Approval and Consent to participate

To carry out the study, the project was sent to the Ethics Committee in Research on Human Beings of the Instituto Superior de Ciências da Saúde, Universidade Agostinho Neto (n.º 904/GD/ISCISA/UAN/2021) and by the Pedagogical and Scientific Department. from Dispensario Anti-tuberculosis e Leprosy (nr. 55/DPC/DATL/2021), to participate in the study, all patients were informed about the nature and objectives of the study and gave their informed consent before being included in the study.

Consent for publication

All authors gave their consent for the present manuscript to be submitted to the journal Infectious Diseases of Poverty.

Availability of data and materials

All data used in the present study can be obtained from the Dispensario Anti-tuberculosis e Lepra de Luanda, located in Maianga, in the municipality of Luanda. The data analyzed by the authors can be obtained through the database compiled by the authors, however, given the ethical criteria, they were securely coded so that they do not allow the identification of patients included in the study.

Competing interests

All authors of the present study declare that there is no conflict of interest in the conduct and publication of this study.

Funding

The authors received no specific funding for this work.

Authors' contributions

Conceptualization: TOM, ENMS. Data curation: ENMS, EKC, ATT, SRS, MC, CAPS, CSS, EEV. Formal analysis: ENMS, EKC, SRS, ATT, MC, CAPS, CSS, EEV. Investigation: ENMS, TOM Project administration: ENMS, EKC, SRS, MC, CAPS, CSS, EEV. Supervision: ENMS. Validation: ENMS, EKC, ATT, SRS, MC, CAPS, CSS, EEV, OFSH. Writing – original draft: ENMS, EKC, CSS. Writing – review & editing: ENMS, EKC, SRS, ATT, MC, CAPS, CSS, EEV, TOM. All authors have seen and approved the submitted version of this manuscript.

Acknowledgements

The authors thank all study participants for agreeing to participate in the research and providing all the information necessary for this study to become a reality. We thank Dispensario Anti-tuberculosis e Lepra, ICISA, CEIP/UPRA, CISA/INIS, and CFS for their scientific, technical, and institutional support.

References

1. Grijó, M.P.S.M.C. Doença de Hansen: abordagem baseada num caso clínico. Universidade de Lisboa. Faculdade de Medicina. Lisboa. 2020. [Last accessed August 2, 2022].
2. Santacroce L, Del Prete R, Charitos IA, Bottalico L (2021) Mycobacterium leprae: A historical study on the origins of leprosy and its social stigma. Infez Med 29:623-632.
3. Pessoa, S.F.S.M.M. Hanseníase no brasil: uma revisão literária, nos anos de 2014 a 2019. Universidade federal do Rio Grande do Norte. Brasil. 2019. [Last accessed August 2, 2022].
4. WHO. The Global Leprosy Strategy 2016–2020; Accelerating towards a leprosy free world. [Last accessed August 3, 2022].
5. Paredes CF, Montes de Oca Sanchez G, White C (2020) Global Leprosy Status in 2020: Still Losing Touch. Ann Acad Med Singapore 49:1-2.
6. Portal de Angola. 2022. Luanda com mais de 100 novos casos de lepra. [Last accessed August 3, 2022].
7. Osten T.H. Assimetria de anticorpos contra os grupos sanguíneos A e B Galα1-3Gal desfavorece o grupo B contra infecção por HIV. Tese de Doutorado Universidade Federal Rio Grande do Sul, 2010. [Last accessed August 5, 2022].
8. Novaretti B, Carla A, Zago MC (2019) Molecular aspects of the ABO Blood System. Rev Bras. Hematol Hemoter 25:47-58.
9. Abegaz SB (2021) Human ABO Blood Groups and Their Associations with Different Diseases. Biomed Res Int 2021:6629060.
10. Khoudri I, Elyoussfi Z, Mourchid Y, Youbi M, Bennani Mechita N, et al., (2018) Trend analysis of leprosy in Morocco between 2000 and 2017: Evidence on the single dose rifampicin chemoprophylaxis. PLoS Negl Trop Dis 12: e0006910.
11. Sacomboio ENM (2021) ABO/Rh Blood Groups and Chronic Diseases in Angolan Patients. Am J Biomed Sci & Res 13.
12. Sacomboio ENM, Sassoke JL, Hungulo OFS, Ekundi-Valentim E, Cassinela EK, et al., (2021) Frequency of ABO/Rh Blood Groups and Social Condition of Hypertensive Patients in Luanda. J Blood Disord Med 4: dx.doi.org/10.16966/2471-5026.125.
13. Sacomboio ENM, Neto CR, Hungulo OFS, Ekundi-Valentim E (2021) Blood Group (ABO/Rh) and Clinical Conditions Common in Children with Nephrotic Syndrome and Sickle Cell Anemia in Angola. J Blood Disord Med 4: dx.doi.org/10.16966/2471-5026.128.
14. Sacomboio E, Sebastião D, Sacomboio-Filho F (2020) Sickle Cell Trait and Blood Groups (ABO and Rh) in Angolans Submitted to Hemoglobin Electrophoresis. Hematol Oncol Curr Res 2:1004.
15. Liu J, Zhang S, Liu M, Wang Q, Shen H, et al., (2018) Distribution of ABO/Rh blood groups and their association with hepatitis B virus infection in 3.8 million Chinese adults: A population-based cross-sectional study. J Viral Hepat 25:401-411.
16. Hambridge T, Nanjan Chandran SL, Geluk A, Saunderson P, Richardus JH (2021) Mycobacterium leprae transmission characteristics during the declining stages of leprosy incidence: A systematic review. PLoS Negl Trop Dis 15: e0009436.
17. Nery JS, Ramond A, Pescarini JM, Alves A, Strina A, et al., (2019) Socioeconomic determinants of leprosy new case detection in the 100 Million Brazilian Cohort: a population-based linkage study. The Lancet Global Health 7: e1226–e1236.
18. World Health Organization (2019) Weekly epidemiological record. Global leprosy update, 2019. [cited 07 August 2022].
19. Cavalcante Trindade L, Da Silveira Mendes M, Conceição Martins L, Carlos Evangelista de A Bonfim A, Fonseca FLA (2021) Co-infection leprosy and tuberculosis: a systematic review. J Infect Dev Ctries 15:1569-1577.
20. Bhandari J, Awais M, Robbins BA, et al. Leprosy. [Updated 2021 Nov 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing.
21. Gupta B, Gupta S, Chaudhary M, Raj AT, Awan KH, et al., (2020) Hematological alterations in lepromatous leprosy: A cross-sectional observational study. Disease-a-Month 66:100919.
22. Sacomboio ENM, dos Santos Sebastião C, Salvador STdC, João JA, Bapolo DVS, et al. (2022) Evaluation of blood cell count parameters as predictors of treatment failure of malaria in Angola: An observational study. PLOS ONE 17: e0267671.