Seroepidemiology of human retroviruses in Ogun State of Nigeria

How do socioeconomic determinants of health affect the likelihood of living with HTLV-1 globally? A systematic review with meta-analysis

Introduction

Human T Lymphotropic Virus type 1 (HTLV-1) is a neglected retrovirus associated with many clinical disorders, most notably Adult T-cell Leukemia/Lymphoma and HTLV-1-Associated Myelopathy (HAM). Found in endemic clusters across the world, high prevalence has been reported in minoritized groups who suffer from health inequities. This study investigates the association between HTLV-1 prevalence and the following socioeconomic determinants of health: education, income, and employment, which are markers of health inequity.

Methods

A systematic review was conducted by searching the following databases: Ovid/Medline, Embase, Global Health Database, Web of Science, LILACS and SciELO. Primary studies in English, Spanish and Portuguese mentioning HTLV-1 and one of education, income and/or employment were included. A random-effects meta-analysis was performed, and odds ratios (OR) were calculated to determine the association between these socioeconomic determinants of health and HTLV-1 prevalence.

Results

42 studies were included. The likelihood of having HTLV-1 was higher in individuals with less than completed primary education compared to those who completed primary education (OR 1.86 [95% CI 1.34-2.57]; p < 0.01). This may be because individuals with low education have reduced access to and understanding of health information, thus increasing the prevalence of risk factors associated with HTLV-1 infection. No other determinants were found to be statistically significant.

Conclusion

Fewer years of schooling are associated with increased likelihood of contracting HTLV-1. Therefore, health promotion materials and public health policies regarding HTLV-1 must consider those with lower educational levels to effectively reduce disease transmission.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=335004, identifier (CRD42022335004).

Geographic distribution, clinical epidemiology and genetic diversity of the human oncogenic retrovirus HTLV-1 in Africa, the world's largest endemic area

The African continent is considered the largest high endemic area for the oncogenic retrovirus HTLV-1 with an estimated two to five million infected individuals. However, data on epidemiological aspects, in particular prevalence, risk factors and geographical distribution, are still very limited for many regions: on the one hand, few large-scale and representative studies have been performed and, on the other hand, many studies do not include confirmatory tests, resulting in indeterminate serological results, and a likely overestimation of HTLV-1 seroprevalence. For this review, we included the most robust studies published since 1984 on the prevalence of HTLV-1 and the two major diseases associated with this infection in people living in Africa and the Indian Ocean islands: adult T-cell leukemia (ATL) and tropical spastic paraparesis or HTLV-1-associated myelopathy (HAM/TSP). We also considered most of the book chapters and abstracts published at the 20 international conferences on HTLV and related viruses held since 1985, as well as the results of recent meta-analyses regarding the status of HTLV-1 in West and sub-Saharan Africa. Based on this bibliography, it appears that HTLV-1 distribution is very heterogeneous in Africa: The highest prevalences of HTLV-1 are reported in western, central and southern Africa, while eastern and northern Africa show lower prevalences. In highly endemic areas, the HTLV-1 prevalence in the adult population ranges from 0.3 to 3%, increases with age, and is highest among women. In rural areas of Gabon and the Democratic Republic of the Congo (DRC), HTLV-1 prevalence can reach up to 10-25% in elder women. HTLV-1-associated diseases in African patients have rarely been reported in situ on hospital wards, by local physicians. With the exception of the Republic of South Africa, DRC and Senegal, most reports on ATL and HAM/TSP in African patients have been published by European and American clinicians and involve immigrants or medical returnees to Europe (France and the UK) and the United States. There is clearly a huge underreporting of these diseases on the African continent. The genetic diversity of HTLV-1 is greatest in Africa, where six distinct genotypes (a, b, d, e, f, g) have been identified. The most frequent genotype in central Africa is genotype b. The other genotypes found in central Africa (d, e, f and g) are very rare. The vast majority of HTLV-1 strains from West and North Africa belong to genotype a, the so-called 'Cosmopolitan' genotype. These strains form five clades roughly reflecting the geographic origin of the infected individuals. We have recently shown that some of these clades are the result of recombination between a-WA and a-NA strains. Almost all sequences from southern Africa belong to Transcontinental a-genotype subgroup.

Prevalence of human T-lymphotropic virus 1/2 in Nigeria's capital territory and meta-analysis of Nigerian studies

Objectives:

This study was aimed at determining human T-lymphotropic virus 1/2 prevalence among apparently healthy, immunocompromised and haematologic malignant individuals in Nigeria’s capital, as well as meta-analysis of all Nigerian studies until date.

Methods:

A total of 200 participants were recruited into a cross-sectional study. In total, 1 mL each of sera and plasma were obtained from 5 mL blood of each participant and analysed for antibodies to human T-lymphotropic virus 1/2 using enzyme-linked immunosorbent assay; positive samples confirmed with qualitative real-time polymerase chain reaction, followed by statistical and meta-analysis. Sociodemographic characteristics and possible risk factors were assessed via questionnaires.

Results:

Enzyme-linked immunosorbent assay yielded 1% prevalence which was confirmed to be zero via polymerase chain reaction. A total of 119 (59.5%) of the participants were male, while the mean age was 35.28 ± 13.61 years. Apart from sex and blood reception/donation, there was generally a low rate of exposure to human T-lymphotropic virus–associated risk factors. Meta-analysis revealed pooled prevalence of human T-lymphotropic virus 1 and 2 to be 3% and 0%, respectively, from Nigerian studies.

Conclusion:

This study discovered zero prevalence of human T-lymphotropic virus 1/2 from five major hospitals in Nigeria’s capital, exposing the importance of confirmatory assays after positive antibody detection assay results. Meta-analysis highlighted the existence of very few reliable Nigerian studies compared to the demography of the nation. Large-scale epidemiological studies and routine screening of risk populations are therefore needed since Nigeria lies in the region of endemicity.

Seroprevalence and coprevalence of HIV and HBsAg in Nigerian children with/without protein energy malnutrition

In order to assess the seroprevalence and coprevalence of hepatitis-B surface antigen (HBsAg), human immunodeficiency virus-1 and -2 (HIV-1 and -2) antibodies in Nigerian children with/without protein energy malnutrition (PEM), we studied plasma specimens of 206 children with PEM and 200 apparently healthy reference children aged between 1 and 3 years by enzyme-linked immunosorbent assays (ELISA). HIV-seropositive cases were confirmed by immunoblotting (IB). Of the children studied, eight (4%) of the healthy and four (1.9%) of the malnourished (P = 0.22, Fisher's exact test) were positive for HIV-1 antibodies, 40 (20%) of the healthy and 54 (26%) of the malnourished (P = 0.14) were positive for HBsAg, and five (2.5%) of the healthy and four (1.9%) of the malnourished (P = 0.70) were positive for both HIV-1/HBsAg. No case of HIV-2 antibodies was found. While the seroprevalence of HBsAg was higher in the malnourished subjects, the reverse was the case with HIV antibodies. However, all the four HIV-1-positive malnourished children and five of eight of the HIV-1-positive reference children were simultaneously positive for HBsAg. This is the first epidemiological report on the seroprevalence and coprevalence of HIV and HBsAg in apparently healthy and malnourished Nigerian children.

Women and the Risk of HIV Infection in Nigeria: Implications for Control Programs

AIDS is a growing public health problem in Nigeria. Since 1984 when AIDS was officially reported in the country, the number of persons infected with HIV and those with AIDS continue to increase rapidly. This trend is likely to persist in the coming years because, in spite of a high level of public awareness about AIDS, many Nigerians continue to engage in behaviors, such as unprotected sexual networking, which would raise their risk of exposure to HIV. Women in Nigeria are particularly susceptible to HIV infection and its consequences because existing sexual norms place them at a disadvantage in that they are unable to control the sexually risky behaviors of their spouses or take action that would limit their risk of exposure. The current economic crisis in Nigeria has also caused many women to go into full-time commercial sex work or enter other occupations in which they are predisposed to being lured or forced to having sexually risky relationships with men. Unfortunately, the current AIDS control intervention in Nigeria do not address these issues. This article draws attention to the biological, cultural, and economic conditions which make women in Nigeria susceptible to HIV infection and recommends how to overcome them.

Fears of AIDS in Nigerian students: dimensions of the fear of AIDS Scale (FAIDSS) in west Africa

A study based on a sample of 2500 individuals aged 18 years and over in six west African cities was undertaken for the purpose of determining the cross-cultural consistency and replicability of fears about AIDS. A factor analysis of the data obtained confirmed a similar factor structure to that reported in Australia. Implications for the prevention of HIV transmission in Nigeria and other west African countries is discussed. Our findings showed that the fear of AIDS Scale (FAIDSS) is a reliable index of fear of aids and is readily scaleable. Other implications for health education are considered.