HTLV-I/II infection in pregnant women in Paris

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.

Epidemiological Aspects and World Distribution of HTLV-1 Infection

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 Thé 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 only approximately 1.5 billion of individuals originating from known HTLV-1 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.

Retrospective study of the prevalence of human T-cell lymphotropic virus-type 1/2, HIV, and HBV in pregnant women in Argentina

This study shows first data on HTLV-1/2 seroprevalence among pregnant women in the non-endemic region of Argentina. In a retrospective study a representative sample (n = 3,143) of the pregnant women registered in the health public service in the province of Córdoba was evaluated. HTLV-1/2 seroprevalence was 0.191% +/- 0.0857 [IC 0.022-0.359]. This prevalence was 10 times higher in pregnant women than in blood donors [0.019 (4/21.183)]. The pregnant women would reflect the epidemiology of the general population more accurately since it constitutes a more heterogeneous group than that of blood donors. The prevalence of infection with HIV was 2.8 times higher than that of HTLV-1/2 (P < 0.05) and the presence of any of these two viruses was not a subrogating indicator of the presence of the other (Goodman and Kruskal's Tau coefficient = 0.0092). The prevalence of HBV was not significantly different from that of HTLV-1/2 (P > 0.05). We consider that it is necessary to carry out continuous studies in order to define the main risk factors for infection of these women. Thus, a decision could be made to apply the best policy in public health to prevent vertical transmission of the virus in Argentina.

The seroepidemiology of human T-lymphotropic viruses: types I and II in Europe: a prospective study of pregnant women

BACKGROUND

Up to 20 million persons are infected with the human retroviruses human T-lymphotropic virus (HTLV)-I and HTLV-II globally. Most data on the seroprevalence of HTLV-I and HTLV-II in Europe are from studies of low-risk blood donors or high-risk injection drug users (IDUs). Little is known about the general population.

METHODS

A prospective anonymous study of HTLV-I and HTLV-II seroprevalence among 234,078 pregnant women in Belgium, France, Germany, Italy, Portugal, Spain, and the United Kingdom was conducted. Maternal antibody status was determined by standard methods using sera obtained for routine antenatal infection screens or eluted from infant heel prick dried blood spots obtained for routine neonatal metabolic screens.

RESULTS

Anti-HTLV-I/II antibodies were detected and confirmed in 96 pregnant women (4.4 per 10,000, 95% confidence interval [CI]: 3.5-5.2). Of these, 73 were anti-HTLV-I, 17 were anti-HTLV-II, and 6 were specifically anti-HTLV but untyped. The seroprevalence ranged from 0.7 per 10,000 in Germany to 11.5 per 10,000 in France.

CONCLUSIONS

Pregnant women better reflect the general population than blood donors or IDUs. The seroprevalence of HTLV-I and HTLV-II in Western Europe is 6-fold higher among pregnant women (4.4 per 10,000) than among blood donors (0.07 per 10,000). These data provide a robust baseline against which changes in HTLV-I and HTLV-II seroprevalence in Europe can be measured.

Soroprevalência de vírus linfotrópico de células T humanas, vírus da imunodeficiência humana, sífilis e toxoplasmose em gestantes de Botucatu - São Paulo - Brasil: fatores de risco para vírus linfotrópico de células T humanas

Com o objetivo de estudar a soroprevalência de vírus linfotrópico de células T humanas I/II (HTLV-I/II), vírus da imunodeficiência humana, sífilis e toxoplasmose, em gestantes atendidas em unidade básicas de saúde do município de Botucatu - São Paulo - Brasil, bem como os fatores de risco para a infecção pelo HTLV -I/II, foram realizados inquérito sorológico e avaliação dos resultados de exames solicitados na rotina do prénatal. Em 913 gestantes, a soroprevalência de HTLV- I e de HTLV- II foi de 0,1%. Sífilis, toxoplasmose e infecção pelo HIV foram encontradas. Nenhum dos fatores de risco pesquisados mostrou-se seguro para identificar gestantes com infecção pelo HTLV- I/II. A comparação da proporção de gestantes infectadas e de doadores de sangue da região sudeste do Brasil com testes reagentes para HTLV- I/II não mostrou diferença estatística.

Prevalence of HTLV infection in pregnant women in Spain

OBJECTIVE

To estimate the prevalence of HTLV infection among pregnant women in Spain.

METHODS

A commercial ELISA incorporating HTLV-I and HTLV-II antigens was used for HTLV antibody screening. Repeatedly reactive samples were further examined by western blot. Moreover, confirmation with PCR was performed when cells were available.

RESULTS

20,366 pregnant women in 12 different Spanish cities were tested in a 3 year period (July 1996 to August 1999). 32 samples were repeatedly reactive by ELISA, and 10 of them were confirmed as positive by western blot (eight for HTLV-II and two for HTLV-I). In addition, three of 13 women who had an indeterminate western blot pattern yielded positive results for HTLV-II by PCR. All 11 HTLV-II infected women had been born in Spain, and all but one were former drug users. Seven of them were coinfected with HIV-1. One HTLV-I infected woman was from Peru, where HTLV is endemic and where she most probably was infected during sexual intercourse.

CONCLUSION

The overall prevalence of HTLV infection among pregnant women in Spain is 0.064% (13/20,366), and HTLV-II instead of HTLV-I is the most commonly found variant. A strong relation was found among HTLV-II infection and specific epidemiological features, such as Spanish nationality and injecting drug use. Although HTLV-II can be vertically transmitted, mainly through breast feeding, both the low prevalence of infection and its lack of pathogenicity would not support the introduction of HTLV antenatal screening in Spain.

HTLV-I transmission from mother to child

Human T-lymphotropic virus type I (HTLV-I), a causative agent of adult T-cell leukemia, (ATL) is transmitted from mother to child. ATL cells originate from the CD4 subset of peripheral T cells. The main route of mother-to-child transmission is postnatal breast-feeding. Refraining from breast-feeding or limiting the duration of breast-feeding can reduce the risk of mother-to-child transmission. Other than postnatal breast-feeding, there seem to be two routes of HTLV-I transmission from mother to child. One is intrauterine transmission, and the other is via saliva. Intrauterine transmission is rare, although proviral DNA is detected in cord blood samples. HTLV-I proviruses in the cord blood may be defective. HTLV-I proviral DNA and antibodies against HTLV-I are also detected in saliva. However, no report has been published so far which showed direct evidence of HTLV-I transmission via saliva. The placenta can be infected by HTLV-I, but infection does not reach the fetus, possibly apoptosis of placental villous cells because it is induced by HTLV-I infection.

Seroepidemiology of the human T-cell leukaemia/lymphoma viruses in Europe. The HTLV European Research Network

An extensive collaboration of laboratories and investigators has been developed to define the seroprevalence of human T-cell leukaemia/ lymphoma virus type I and II (HTLV-I and -II) infection in Europe. An algorithm for serological screening for HTLV-I and -II infection has been established by consensus. Data from screening almost 4 million subjects, including many unpublished studies, which conform to this algorithm are presented. In extensive studies the seroprevalence of HTL.V-I/II in blood donors is low, ranging from < 1 in 100,000 to 30 in 100,000 donors and is due predominantly to HTLV-I. In antenatal clinics in France and the United Kingdom the seroprevalence of HTLV-I is > 0.2%, but surveillance in this setting has been limited and extensive study of the seroprevalence of HTLV-I/II infection in pregnant women in Europe is urgently required to determine the need for HTLV-I/II antenatal screening. HTLV-I is present in populations who have immigrated to Europe from endemic areas and is spreading into indigenous European populations, particularly through sexual transmission to females. HTLV-II infection is present predominantly amongst IVDU and is usually a coinfection with HIV-I. There are considerable regional differences in HTLV-II seroprevalence.

The epidemiology of HTLV-I in Europe

Although human T-lymphotropic virus type I (HTLV-I) infection in Europe is thought to be unusual except amongst people who have immigrated from countries where HTLV-I is endemic, the screening of blood donors has revealed a low seroprevalence across Europe, not only in donors originating from endemic areas but also in the indigenous population. Data from blood donors should not be extrapolated to other groups because blood donors are selected to be at low risk of parenterally transmissible infections. Unfortunately only small studies have been conducted in other population groups, including women attending antenatal clinics, despite the importance of breast-feeding in vertical transmission. Data from metropolitan areas of the United Kingdom and France suggest that the seroprevalence of HTLV-I in pregnant women is up to 100 times higher than in blood donors. HTLV-I infection is also more common in patients attending sexually transmitted disease clinics, whilst HTLV-II is endemic in many cities amongst intravenous drug users. There are few incidence data for diseases associated with HTLV-I, even though cases of adult T-cell leukemia/lymphoma and HTLV-I-associated myelopathy have been described in many European countries. Data on the seroprevalence of HTLV-I in central and eastern Europe are scanty but the few published studies suggest a higher rate than has been documented in western Europe.

Human T-cell lymphotropic virus type I infection and pregnancy: a case-control study and 12-month follow-up of 135 women and their infants

Human T-cell lymphotropic virus type I (HTLV-I) infection is common in Gabon, but its influence on pregnancy is unknown. A single case of acute T-cell leukemia in a pregnant woman has been reported in the literature, but, as far as we know, we present the first case-control study analyzing the relationship between HTLV-I seropositivity and the course and outcome of pregnancy. The study concerned 45 HTLV-I seropositive pregnant women matched with 90 seronegative pregnant women. None has clinical features of HTLV-I infection during pregnancy or during the year after delivery. HTLV-I seropositivity did not significantly affect the course or outcome of pregnancy. After losing maternal antibodies to HTLV-I, none of the infants had seroconversion to HTLV-I 1 year after birth. Filaria infection was correlated with HTLV-I seropositivity, but confounding factors may account for this observation.

[Investigation of a transfusion contaminated by HTLV-I virus]

In front of the successive development of an HTLV-I seroconversion and a neuromyelopathy in a French Caucasian following a cardiac transplantation, an ascendant epidemiologic investigation must be manage to search a risk factor or a possible blood donor contaminated with HTLV-I virus. We selected an HTLV-I seropositive donor whose RBC participated to the patient's transfusion. This woman from Martinique island was a regular donor in our blood center and a second investigation was initiated to examine the patients transfused with the blood products issued from her previous donation. Nine were identified and controlled among them a patient who has received a RBC was found HTLV-I seropositive. An evaluation of the infectivity of the different blood products according to their type and specificity has been done. These data confirm that transmission of the HTLV-I is possible through donation of healthy seropositive donor and can induce the development of associated pathology, and prove the importance of screening blood donors for HTLV-I antibodies.