VERTICAL TRANSMISSION OF HTLV-I/II: A review

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.

Manifestações infanto-juvenis da infecção pelo vírus linfotrópico de células T humanas (HTLV-I)

“…3 In Campo Grande (MS), an infection rate of 10% was observed among Japanese immigrants and their descents, and, in Salvador (BA), a rate of 25% was observed among injecting drug users. 2 The overall prevalence of this infection in the general population of Salvador was estimated to be 1.76%. 5 An HTLV-I infection frequency of 1.1% was observed among pregnant women in Belo Horizonte (MG) and of 0.84% in Salvador (BA).…”

“…2 Sexual transmission is primarily from men to women, at a rate of around 61%, whereas transmission from women to men is uncommon, at around 0.4%.…”

“…Transmission via human milk is almost always vertical, but it may occur by means of breastfeeding by wet-nurses or cross-breastfeeding (horizontal transmission). 2 The milk of mothers who are seropositive for HTLV-I contains infected cells and experimental infection has been achieved administering this milk orally to marmosets. [7][8][9] In areas where HTLV-I is endemic, from 7 to 42% of breastfed children acquire the infection.…”

“…6 It should be pointed out that a positive test before 1 year of age may not represent infection and may be merely the result of maternal antibodies passing through the placenta. 2 In cases that cannot be confirmed using the western blot technique, molecular testing should be carried out, the PCR being the most often used. Detection by PCR does not depend on antibody production because it directly detects the proviral DNA.…”

“…This is also the method of choice for very early investigation of infection. 2 The principal diseases related to HTLV-I…”