Dmm. Borducchi et al., HTLV-I infection among relatives of patients with adult T-cell Leukemia/Lymphoma in Brazil: Analysis of infection transmission, LEUK LYMPH, 31(3-4), 1998, pp. 411-416
We examined the presence of HTLV-I infection among 66 family members of 13
patients with well documented ATL to investigate the routes of HLTV-I trans
mission in a Southeast region of Brazil. HTLV-I infection was screened by a
n enzyme immunossay (ELISA) test and an repeatedly positive or indeterminat
e ELISA samples were further tested by a Western-Blot (WB) technique. Indet
erminate and inconclusive WE samples were confirmed by a polymerase chain r
eaction (PCR). ELISA results showed that 40 (60.6%) individuals were not in
fected; 16 (24.2%) were positive; and 10 (15.2%) were undetermined. Among 1
6 ELISA positive subjects, 14 (87.5%) were confirmed to be positive by WE w
hile 2 (12.5%) showed inconclusive results. Based on the laboratory data, q
uestionnaire analysis, and family/epidemiological studies, we concluded tha
t HTLV-I vertical transmission occurred in 6 of the 13 families. In 3 of th
ese 6 families, the horizontal transmission also could be demonstrated. An
isolated horizontal transmission was detected in one family, and in 6 famil
ies we did not find any infected family member. All HTLV-I-infected persons
were clinically asymptomatic. The occurrence of an effective HTLV-I vertic
al transmission detected by the present study suggest that HTLV-I infection
is endemic in the Southeast region of Brazil. Consistent with the modes of
transmission, the HTLV-I antibody seroprevalence was greater in relatives
of ATL patients than in the general blood donor Brazilian population (0.4%)
. In addition, the present data suggest that HTLV-I carries a high infectiv
ity rate but a low virulence.