Human T-lymphotropic virus type 1 infection is frequent in rural communities of the southern Andes of Peru

Human T-Lymphotropic Virus Type 1 and Cryptococcosis Infection, an Underdiagnosed Association: Case Series and Literature Review

Clinical and epidemiological features of 7 human immunodeficiency virus-negative Peruvian patients coinfected with human T-lymphotropic virus type 1 (HTLV-1) and cryptococcosis (2006-2017) were studied. Most cases had meningeal involvement, were male, and originated from Peru's jungle. Patients with cryptococcosis should be tested for HTLV-1 in endemic areas of this retrovirus.

Human T Cell Lymphotropic Virus Type 1 Global Prevalence Associated with the Human Development Index: Systematic Review with Meta-Analysis

In 2012, the number of people infected with human T cell lymphotropic virus type 1 (HTLV-1) was estimated to be 10 million worldwide. Prevalence varies according to geographic location, ethnic factors, sex, age, populations exposed to risk factors, income, and education, reaching countries with the worst socioeconomic scenarios. There is a need to determine the current global prevalence of HTLV-1 and examine its association with countries' human development index (HDI) to provide data for global health policy. Systematic review with meta-analysis is according to PRISMA 2020 recommendations. It was registered at PROSPERO, CRD42021223146. Prevalence or cross-sectional studies of HTLV-1 infection with at least 100 participants, screening, and confirmatory serologic testing were included. Studies with incomplete or unavailable results or with duplicate information were excluded. Data were selected by two independent investigators and analyzed using R software, a metapackage that generated the forest plots [95% confidence interval (CI)]. Heterogeneity was assessed using the I² statistic, and funnel plot asymmetry was assessed using Egger's test. Countries were compared using an HDI cutoff ≥0.8. Methodological quality was assessed using Joanna Briggs Institute (JBI) criteria. The overall prevalence of HTLV-1 infection was 0.91% (95% CI: 0.80-1.02, p < .0001) and was higher in low HDI countries [1.18% (95% CI: 1.03-1.34)] than in high HDI countries [0.41% (95% CI: 0.27-0.57)]. Prevalence varied according to the populations studied: it was higher in the general population [1.65% (95% CI: 1.08-2.34)] compared to pregnant women [0.34% (95% CI: 0.17-0.57)] and blood donors [0.04% (95% CI: 0.01-0.08)]. Consistently, prevalence for each population group was higher in low HDI countries than in high HDI countries. The worldwide prevalence of HTLV-1 infection is highly heterogeneous, with a global prevalence of 0.91%. In high HDI countries, the observed prevalence is approximately three times lower than in low HDI countries. In the general population, the observed prevalence is about 5 times higher than in pregnant women and 41 times higher than in blood donors.

Clinical and Public Health Implications of Human T-Lymphotropic Virus Type 1 Infection

Human T-lymphotropic virus type 1 (HTLV-1) is estimated to affect 5 to 10 million people globally and can cause severe and potentially fatal disease, including adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The burden of HTLV-1 infection appears to be geographically concentrated, with high prevalence in discrete regions and populations. While most high-income countries have introduced HTLV-1 screening of blood donations, few other public health measures have been implemented to prevent infection or its consequences. Recent advocacy from concerned researchers, clinicians, and community members has emphasized the potential for improved prevention and management of HTLV-1 infection. Despite all that has been learned in the 4 decades following the discovery of HTLV-1, gaps in knowledge across clinical and public health aspects persist, impeding optimal control and prevention, as well as the development of policies and guidelines. Awareness of HTLV-1 among health care providers, communities, and affected individuals remains limited, even in countries of endemicity. This review provides a comprehensive overview on HTLV-1 epidemiology and on clinical and public health and highlights key areas for further research and collaboration to advance the health of people with and at risk of HTLV-1 infection.

HTLV-1 Is Also a Sexually Transmitted Infection

HTLV-1 is a retrovirus which causes diverse diseases in 10% of its infected population, significantly worsening their quality of life and mortality rate. Even though it is globally distributed and is endemic in many countries (including Peru), it is still highly neglected. It spreads through vertical, sexual and parenteral transmission. As no effective treatment against this virus exist, prevention is required to contain it. The World Health Organization published a technical report on the matter in 2021, with the collaboration of international HTLV-1 experts. However, neither the impact of sexual transmission (cause of the majority of adult cases and infection in non-endemic areas) nor its prevention were considered. Evidence is presented, which shows the magnitude of sexual transmission, its risk factors and preventive measures; hoping it will encourage health workers to help eradicate this infection.

Clinical, Radiological and Functional Characteristics of Pulmonary Diseases among HTLV-1 Infected Patients without Prior Active Tuberculosis Infection

The lifelong infection with the human T lymphotropic virus type 1 (HTLV-1) has been associated with a variety of clinical manifestations; one of the less-explored is HTLV-1-associated pulmonary disease. Imaging of lung damage caused by the HTLV-1 hyperinflammatory cascade can be similar to sequelae from TB infection. Our study aims to describe the pulmonary lesions of HTLV-1-positive patients without past or current active TB and evaluate pulmonary function. We found that nine out of fourteen patients with no known TB disease history presented bronchiectasis, mainly found bilaterally while five presented pulmonary fibrosis. A normal pattern was found in most patients with a pulmonary functional test. Furthermore, there was no association between the PVL and the chest-CT scan findings, nor with spirometry results. However, the sample size was insufficient to conclude it.

Screening for Human T-Cell Lymphotropic Virus (HTLV) in Pregnant Women in the Peruvian Amazon and Systematic Review with Meta-Analysis of HTLV Infection in Peru

Background. Human T-cell lymphotropic virus type 1 (HTLV-1) is responsible for tropical spastic paraparesis and HTLV-1-associated leukemia/lymphoma. The infection is endemic in some areas of Peru, but its prevalence in the Peruvian Amazon is not well established. We aimed to assess the seroprevalence of HTLV-1 infection in pregnant women in the Peruvian Amazon. Moreover, we performed a systematic literature review and meta-analysis of the seroprevalence of HTLV infection in Peru. (2) Methods. This is a prospective cross-sectional study involving pregnant women attending health centers in the city of Iquitos, Peru, in May and June 2019. The presence of antibodies against HTLV-1 was assessed using ELISA (HTLV I + II ELISA recombinant v.4.0, Wiener lab, Rosario, Argentina). Positive cases were confirmed by Western Blot and HTLV-1 proviral load. (3) Results. The study included 300 pregnant women with a mean age of 26 years (standard deviation [SD] 6.4). Five patients were diagnosed with HTLV-1 infection (prevalence 1.7%, 95% confidence interval (CI) 0.7% to 3.8%). Pregnant women with HTLV-1 infection were discretely younger (mean age 22.6 [SD 22.6] vs 26.8 [SD 6.3]; p = 0.128). None of the five women had been transfused, and all were asymptomatic. Two (40%) also had a positive serology for Strongyloides, but larvae were not detected in any of the parasitological stool studies. The systematic review component identified 40 studies, which showed that the prevalence of HTLV infection in the general population was 2.9% (95% CI 1.2% to 5.3%) and in women of childbearing age, 2.5% (95% CI 1.2% to 4.0%). (4) Conclusion. The prevalence of HTLV-1 in the Peruvian Amazon basin is about 1.7%, indicating an endemic presence. Screening for HTLV-1 in prenatal care is warranted.

Lymphotropic Viruses EBV, KSHV and HTLV in Latin America: Epidemiology and Associated Malignancies. A Literature-Based Study by the RIAL-CYTED

The Epstein-Barr virus (EBV), Kaposi sarcoma herpesvirus (KSHV) and human T-lymphotropic virus (HTLV-1) are lymphomagenic viruses with region-specific induced morbidity. The RIAL-CYTED aims to increase the knowledge of lymphoma in Latin America (LA), and, as such, we systematically analyzed the literature to better understand our risk for virus-induced lymphoma. We observed that high endemicity regions for certain lymphomas, e.g., Mexico and Peru, have a high incidence of EBV-positive lymphomas of T/NK cell origin. Peru also carries the highest frequency of EBV-positive classical Hodgkin lymphoma (HL) and EBV-positive diffuse large B cell lymphoma, not otherwise specified (NOS), than any other LA country. Adult T cell lymphoma is endemic to the North of Brazil and Chile. While only few cases of KSHV-positive lymphomas were found, in spite of the close correlation of Kaposi sarcoma and the prevalence of pathogenic types of KSHV. Both EBV-associated HL and Burkitt lymphoma mainly affect young children, unlike in developed countries, in which adolescents and young adults are the most affected, correlating with an early EBV seroconversion for LA population despite of lack of infectious mononucleosis symptoms. High endemicity of KSHV and HTLV infection was observed among Amerindian populations, with differences between Amazonian and Andean populations.

Human T-Cell Lymphotropic Virus Type 1 and associated diseases in Latin America

This narrative review, which is based on a systematic literature search following the PRISMA guidelines, provides a general overview of Human T-cell Lymphotropic Virus type 1 (HTLV-1) and associated diseases: Adult T-cell Leukaemia-Lymphoma (ATLL) and HTLV-1-Associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) in Latin America, focusing on epidemiology and prevention. Using the published information on HTLV-1, ATLL and HAM/TSP prevalence, we present comprehensive and accurate maps and tables, and developed an algorithm to assist in the prevention of HTLV-1 transmission through breastfeeding while considering socio-economic status. Latin America is an interesting scenario to study HTLV-1 because of the diverse origin of its population. Apart from the expected high prevalence in inhabitants of African ancestry, the presence of endemic foci affecting indigenous populations is particularly striking. ATLL prevention is the biggest challenge in this field. Most ATLL cases are transmitted through breastfeeding; thus, prevention methods to avoid ATLL in endemic countries have to be focused on this. In view of the high inequality in most Latin American countries, reduction in breastfeeding duration, freezing/thawing and pasteurisation of breastmilk can be suitable interventions in poor settings, considering that avoiding the risk of malnutrition and infant mortality must be the priority.

Delimitation of the upstream region of NFKBIA gene associated with HTLV-1-associated myelopathy/tropical spastic paraparesis using candidate Tag-SNPs in Peruvian HTLV-1 infected individuals

In Peru, it is estimated that about 150 000-400 000 people carry the Human T-lymphotropic virus 1 (HTLV-1). Only 10% of HTLV-1 carries develop complications related to HTLV-1. HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a chronic disabling inflammatory disease affecting the spinal cord. HAM/TSP produces principally weakness in the lower limbs and bladder disturbances, among other complications. In a previous study, our group identified three SNPs (rs3138053, rs2233406, and rs3138045) located in the promoter region of the NFKBIA gene associated with HAM/TSP. This study aimed to analyze the association between four Tag-SNPs (rs10148482, rs17103274, rs17103282, and rs762009) located in the upstream region of the NFKBIA gene and HAM/TSP, and to delimit the linkage disequilibrium zone in the upstream region of the NFBKIA gene associated with HAM/TSP. The tetra-primers ARMS-PCR technique was used to genotype 4 Tag-SNPs on 140 HAM/TSP patients and 258 asymptomatic carriers. The SNP rs17103282 showed a deviation from Hardy-Weinberg equilibrium (p < .0001). Neither of three Tag-SNPs showed an association with HAM/TSP (P > .05). No linkage disequilibrium between four Tag-SNPs evaluated in this study and previous ones was observed. Here we show the region located in the upstream region of the NFKBIA gene highly associated with HAM/TSP disease in patients infected with HTLV-1 from Lima, Peru.

High prevalence of pulmonary findings in computed tomographies of HTLV-1-infected patients with and without adult-T cell leukemia/lymphoma - implications for staging

Lung involvement has been reported in HTLV-1 carriers and in patients with ATLL. Whether there are differences in the pattern of lung involvement between ATLL and HTLV carriers in North American patients is unknown. We aimed to compare CT pulmonary findings among patients with HTLV-1 infection with and without ATLL. Among 140 patients with HTLV-1 diagnosis, 97 had CT chest available. Of these, 72 (74.2%) had ATLL and 25 (25.8%) did not have ATLL. CT chest abnormalities were present in 90 (92.8%) participants (94.4% in ATLL; 88% in non-ATLL). Higher rates of lymphadenopathy (69.4% versus 24%, p < .01) and lower rates of bronchiectasis (25% versus 48%, p = .04) were seen in ATLL compared to non-ATLL. Our study supports that staging of lung involvement in ATLL should consider HTLV-associated pulmonary findings as not all CT chest abnormalities necessarily represent malignant infiltration.

Adult T-Cell Leukemia/Lymphoma. Review of the Literature

Adult T-cell Leukemia/Lymphoma (ATLL) is an aggressive neoplasm of T lymphocytes associated with Human T-lymphotropic virus type1 (HTLV-1) infection. HTLV-1 is a public health problem because it is endemic in native groups in Latin America, and its infection leads to several chronic diseases as ATLL. We aimed to review current literature of ATLL in order to consider it as a differential diagnosis in front of patients with compatible symptoms. Prognosis is still poor in aggressive and indolent variants, with survival rates from months to few years. Treatment based on chemotherapy, antiretroviral, and allogenic stem cell transplantation are currently improving survival rates, but with limited results.

Silent dissemination of HTLV-1 in an endemic area of Argentina. Epidemiological and molecular evidence of intrafamilial transmission

Background

Molecular and epidemiological studies of transmission routes and risk factors for infection by HTLV-1 are extremely important in order to implement control measures, especially because of the high prevalence of HTLV-1 in several regions of the world. San Salvador de Jujuy, Northwest Argentina, is a highly endemic area for HTLV-1 and foci of tropical spastic paraparesis/HTLV-1-associated myelopathy.

Objective

To gain further insight into the role of intrafamilial transmission of HTLV-1 in a highly endemic region in Argentina.

Method

Cross-sectional study in Northwest Argentina. Epidemiological data and blood samples were collected from 28 HTLV-1 infected subjects (index cases) and 92 close relatives/cohabitants. HTLV-1 infection was diagnosed by detection of antibodies and proviral DNA. The LTR region was sequenced and analyzed for genetic distances (VESPA software), in addition to determination and identification of polymorphisms to define HTLV-1 family signatures.

Results

Fifty seven of the 120 subjects enrolled had antibodies against HTLV-1 and were typified as HTLV-1 by PCR. The prevalence rate of HTLV-1 infection in family members of infected index cases was 31.52% (29/92). The infection was significantly associated with gender, age and prolonged lactation. Identity of LTR sequences and presence of polymorphisms revealed high prevalence of mother-to-child and interspousal transmission of HTLV-1 among these families.

Conclusion

There is an ongoing and silent transmission of HTLV-1 through vertical and sexual routes within family clusters in Northwest Argentina. This evidence highlights that HTLV-1 infection should be considered as a matter of public health in Argentina, in order to introduce preventive measures as prenatal screening and breastfeeding control.

Origin and prevalence of human T-lymphotropic virus type 1 (HTLV-1) and type 2 (HTLV-2) among indigenous populations in the Americas

Human T-lymphotropic virus type 1 (HTLV-1) is found in indigenous peoples of the Pacific Islands and the Americas, whereas type 2 (HTLV-2) is widely distributed among the indigenous peoples of the Americas, where it appears to be more prevalent than HTLV-1, and in some tribes of Central Africa. HTLV-2 is considered ancestral in the Americas and is transmitted to the general population and injection drug users from the indigenous population. In the Americas, HTLV-1 has more than one origin, being brought by immigrants in the Paleolithic period through the Bering Strait, through slave trade during the colonial period, and through Japanese immigration from the early 20^th century, whereas HTLV-2 was only brought by immigrants through the Bering Strait. The endemicity of HTLV-2 among the indigenous people of Brazil makes the Brazilian Amazon the largest endemic area in the world for its occurrence. A review of HTLV-1 in all Brazilian tribes supports the African origin of HTLV-1 in Brazil. The risk of hyperendemicity in these epidemiologically closed populations and transmission to other populations reinforces the importance of public health interventions for HTLV control, including the recognition of the infection among reportable diseases and events.