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Vertical transmission of HTLV-I/II: a review
1Faculdade de Medicina, Universidade Federal da Bahia, Brasil. achilea@svn.com.br
Insights
Vertical transmission of Human T-cell lymphotropic virus type I (HTLV-I) primarily occurs via breastfeeding, but alternative routes exist. Prenatal screening and avoiding breastfeeding can significantly reduce HTLV-I transmission rates.
Area of Science:
- Virology
- Infectious Diseases
- Public Health
Background:
- Human T-cell lymphotropic virus type I (HTLV-I) vertical transmission is predominantly through breastfeeding.
- Alternative transmission routes are suggested by seropositive bottle-fed infants.
- HTLV-I prevalence in pregnant women in Salvador, Brazil, is significant, with associated diseases like adult T-cell leukemia/lymphoma.
Purpose of the Study:
- To evaluate the importance of HTLV-I vertical transmission in Brazil.
- To propose targeted prenatal screening strategies for HTLV-I in Brazil.
- To highlight the need for further research on HTLV-II vertical transmission.
Main Methods:
- Review of existing literature on HTLV-I vertical transmission.
- Analysis of HTLV-I prevalence data in specific populations.
- Comparison of transmission reduction strategies from other countries (e.g., Japan).
Main Results:
- HTLV-I vertical transmission rates in Japan range from 15-25%.
- Prenatal screening and avoidance of breastfeeding reduced transmission by ~80% in Japan.
- Selected high-risk groups for prenatal screening in Brazil are identified.
Conclusions:
- Prenatal screening for HTLV-I is crucial for selected high-risk pregnant women in Brazil.
- Targeted screening can mitigate vertical transmission of HTLV-I.
- Further investigation into HTLV-II vertical transmission is warranted.
Abstract:
The vertical transmission of the human T-cell lymphotropic virus type I (HTLV-I) occurs predominantly through breast-feeding. Since some bottle-fed children born to carrier mothers still remain seropositive with a frequency that varies from 3.3% to 12.8%, an alternative pathway of vertical transmission must be considered. The prevalence rate of vertical transmission observed in Japan varied from 15% to 25% in different surveys. In Brazil there is no evaluation of this form of transmission until now. However, it is known that in Salvador, Bahia, 0.7% to 0.88% of pregnant women of low socio-economic class are HTLV-I carriers. Furthermore the occurrence of many cases of adult T-cell leukemia/lymphoma and of four cases of infective dermatitis in Salvador, diseases directly linked to the vertical transmission of HTLV-I, indicates the importance of this route of infection among us. Through prenatal screening for HTLV-I and the refraining from breast-feeding a reduction of approximately 80% of vertical transmission has been observed in Japan. We suggest that in Brazil serologic screening for HTLV-I infection must be done for selected groups in the prenatal care: pregnant women from endemic areas, Japanese immigrants or Japanese descendents, intravenous drug users (IDU) or women whose partners are IDU, Human immunodeficiency virus carriers, pregnant women with promiscuous sexual behavior and pregnant women that have received blood transfusions in areas where blood donors screening is not performed. There are in the literature few reports demonstrating the vertical transmission of HTLV-II.