The human T-cell leukemia virus type 1 (HTLV-1), identified as the first human oncogenic retrovirus 30 years ago, is not an ubiquitous virus. HTLV-1 is present throughout the world, with clusters of high endemicity located often nearby areas where the virus is nearly absent. The main HTLV-1 highly endemic regions are the Southwestern part of Japan, sub-Saharan Africa and South America, the Caribbean area and foci in Middle East and Australo-Melanesia. The origin of this puzzling geographical or rather ethnic repartition is probably linked to a founder effect in some groups with the persistence of a high viral transmission rate. Despite different socio-economic and cultural environments, the HTLV-1 prevalence increases gradually with age, especially among women in all highly endemic areas. The three modes of HTLV-1 transmission are mother to child, sexual transmission and transmission with contaminated blood products. Twenty years ago, de The and Bomford estimated the total number of HTLV-1 carriers to be 10-20 millions people. At that time, large regions had not been investigated, few population-based studies were available and the assays used for HTLV-1 serology were not enough specific. Despite the fact that there is still a lot of data lacking in large areas of the world and that most of the HTLV-1 studies concern only blood donors, pregnant women or different selected patients or high-risk groups, we shall try based on the most recent data, to revisit the world distribution and the estimates of the number of HTLV-1 infected persons. Our best estimates range from 5-10 millions HTLV-1 infected individuals. However, these results were based on approximately 1.5 billion of individuals originating from known endemic areas with reliable available epidemiological data. Correct estimates in other highly populated regions such as China, India, the Maghreb and East Africa is currently not possible, thus, the current number of HTLV-1 carriers is very probably much higher.

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Epidemiological Aspects and World Distribution of HTLV-1 Infection

Epidemiologic aspects of human T-lymphotropic virus type I (HTLV-I) infection have been thoroughly studied over the course of approximately 25 years since its first description. The geographic distribution of the virus has been defined, with Japan, Africa, Caribbean islands and South America emerging as the areas of highest prevalence. The reasons for HTLV-I clustering, such as the high ubiquity in southwestern Japan but low prevalence in neighboring regions of Korea, China and eastern Russia are still unknown. The major modes of transmission are well understood, although better quantitative data on the incidence of transmission, and on promoting/inhibiting factors, are needed. Epidemiologic proof has been obtained for HTLV-I's causative role in major disease associations: adult T-cell leukemia (ATL), HTLV-associated myelopathy/tropical spastic paraparesis (HAM/TSP), HTLV-associated uveitis and infective dermatitis. However, more and better studies are needed for other apparent disease outcomes such as rheumatologic, psychiatric and infectious diseases. Since curative treatment of ATL and HAM/TSP is lacking and a vaccine is unavailable, the social and financial cost for the individual, his/her family and the health system is immense. For this reason, public health interventions aimed at counseling and educating high-risk individuals and populations are of paramount importance.

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Global epidemiology of HTLV-I infection and associated diseases.

Summary: Human T-cell leukemia virus type 1 (HTLV-1), the first human retrovirus to be discovered, is present in diverse regions of the world, where its infection is usually neglected in health care settings and by public health authorities. Since it is usually asymptomatic in the beginning of the infection and disease typically manifests later in life, silent transmission occurs, which is associated with sexual relations, breastfeeding, and blood transfusions. There are no prospects of vaccines, and screening of blood banks and in prenatal care settings is not universal. Therefore, its transmission is active in many areas such as parts of Africa, South and Central America, the Caribbean region, Asia, and Melanesia. It causes serious diseases in humans, including adult T-cell leukemia/lymphoma (ATL) and an incapacitating neurological disease (HTLV-associated myelopathy/tropical spastic paraparesis [HAM/TSP]) besides other afflictions such as uveitis, rheumatic syndromes, and predisposition to helminthic and bacterial infections, among others. These diseases are not curable as yet, and current treatments as well as new perspectives are discussed in the present review.

Epidemiology, Treatment, and Prevention of Human T-Cell Leukemia Virus Type 1-Associated Diseases

The city of Salvador has the highest prevalence of HTLV-I among blood donors in Brazil. To study the prevalence of HTLV-I among the general population of Salvador, 30 "sentinel surveillance areas" were selected for the investigation of various infectious diseases, and 1385 individuals within these areas were surveyed according to a simple random sample procedure. ELISA was used to screen plasma samples for antibodies to HTLV-I, and the positive samples were tested by a confirmatory assay (Western blotting). The overall prevalence of HTLV-I was 1.76% (23/1385). Infection rates were 1.2% for males and 2.0% for females. Specific prevalence demonstrated an increasing linear trend with age. No one younger than 13 years of age was infected. Multivariate analysis estimated adjusted odds ratios for the association of HTLV-I with age of 9.7 (3.3; 30.4) for females and 12.3 (1.47; 103.1) for males. Less education and income might be associated with HTLV-I infection in females. Phylogenetic analysis of the long terminal repeat fragments showed that most of the samples belonged to the Latin American cluster of the Transcontinental subgroup (Cosmopolitan subtype). For the entire city of Salvador, it is estimated that approximately 40000 individuals are infected with HTLV-I. Our results suggest multiple post-Colombian introductions of African HTLV-Ia strains in Salvador.

https://www.arca.fiocruz.br/bitstream/icict/8136/1/Dourado%20I%20HTLV-I%20in%20the%20general....pdf

HTLV-I in the general population of Salvador, Brazil: a city with African ethnic and sociodemographic characteristics.

Strongyloides stercoralis is the most common human parasitic nematode that is able to complete a life cycle and proliferate within its host. The majority of patients with strongyloidiasis have an asymptomatic infection or mild disease. However, when autoinfection occurs, a high number of infecting larvae can gain access to the bloodstream by penetrating the colonic mucosa leading to a severe hyperinfection and the development of disseminated strongyloidiasis. The human T cell lymphotropic virus type 1 (HTLV-1) predominantly infects T cells and induces spontaneous lymphocyte proliferation and secretion of high levels of type 1 cytokines. Strongyloides stercoralis patients with HTLV-1 co-infection have a modified immunological responses against parasite antigens and co-infection has clinical implications for strongyloidiasis. The high production of IFN-gamma observed in patients co-infected with HTLV-1 and Strongyloides stercoralis decreases the production of IL-4, IL-5, IL-13 and IgE, molecules that participate in the host defence mechanism against helminths. Moreover, there is a decrease in the efficacy of treatment of Strongyloides stercoralis in patients co-infected with HTLV-1. Alterations in the immune response against Strongyloides stercoralis and the decrease in the efficacy of anti-parasitic drugs are responsible for the increased prevalence of Strongyloides stercoralis among HTLV-1 infected subjects and make HTLV-1 infection the most important risk factor for disseminated strongyloidiasis.

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Epidemiological and clinical interaction between HTLV‐1 and Strongyloides stercoralis

https://www.arca.fiocruz.br/bitstream/icict/8199/1/Castro-Filho%20BG%20Distribution....pdf

Distribution of human T-lymphotropic virus type I among blood donors: a nationwide Brazilian study.

A systematic literature review of interoperability in the green Building Information Modeling lifecycle

In the last years the aec (architecture, engineering and construction) industry has been influenced by the development of building information modelling (bim). With the creation of complex systems, the need for efficient in­teroperability arises. Based on a study of bim interoperability dimensions and its levels, this research presents an inter­operability assessment of bim system in the structural domain, especially considering cast-in-place concrete structures, since they present some special challenges for system interoperability. This assessment was conducted by experiments that imported and exported structural models and structural elements through a non-proprietarz standard for bim mod­els (ifc- industry foundation classes). The experiments were conducted twice, with a five year gap from each other, so the evolution of the interoperability could be assessed as well. The results showed that some special characteristics must be considered in order to achieve efficient interoperability for cast-in-place concrete structures – these structures are monolithic and they have reinforcement steel bars that need detailing. Also, the research showed that in the five-year gap there were evolutions in interoperability, like in object identifiers, which had a considerable improvement. However, some of the major problems remain, such as overlapping of structural parts.

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Data interoperability assessment though IFC for BIM in structural design – a five-year gap analysis

The construction industry in its heterogeneity has a need for better communication and process coordination among stakeholders. This lack of coordination is due to barriers in interoperability in strategic, conceptual and technological perspectives. Interoperability is the ability for agents to communicate and exchange data, information and knowledge. Around this definition, literature suggests that Building Information Modelling (BIM) will play an important role in the development of interoperability in the Architecture, Engineering and Construction (AEC) industry. Considering that barriers in interoperability can cause difficulties in the AEC industry (such as design overlapping, coordination issues and many kinds of financial loss), the need for a specific method and tools to assess the level of maturity in this field was perceived. This paper provides an approach to assess interoperability in the AEC domain. It is based on the concerns suggested by the main interoperability frameworks found in literature, such as the European Interoperability Framework (EIF). The interoperability assessment is then structured using the value levels (communication, coordination and cooperation) proposed by Grilo and Jardin-Goncalves (1) as maturity levels. The AEC attributes were then formatted in a multi-criteria decision making structure, AHP (Analytic Hierarchy Process), from which specialists gave their opinion through a questionnaire to determine the perceived level of interoperability. The assessment and diagnosis stage of the research led to the conclusion that data interoperability is still the biggest issue, so a new method to assess interoperability between software and formats is described as a verification experiment, highlighting the main barriers in BIM.

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Marina Figueiredo Muller

Papers

Distribution of human T-lymphotropic virus type I among blood donors: a nationwide Brazilian study.

A systematic literature review of interoperability in the green Building Information Modeling lifecycle

Data interoperability assessment though IFC for BIM in structural design – a five-year gap analysis

Interoperability Assessment for Building Information Modelling

Developing BIM Culture in a University - Past and Future Steps.