HTLV-1 and myelopathy in Salvador (Northeastern Brazil): a case control study Translated title: Estudo caso-controle de mielopatias por HTLV-1 em Salvador

Abstract

The principal aim of the study was to determine the degree of association between cerebrospinal fluid (CSF) that is positive for HTLV-1 and myelopathy in Salvador, Brazil. From the same hospital, twenty-eight cases of myelopathy and twenty-eight cases showing no neurological disorder were studied using blind selection matched 1:1 by age and sex. The twenty-eight pairs underwent HTLV-1 serology tests. In those with a positive result, anti-HTLV-1 antibodies were investigated in the CSF. The ELISA method was used, complemented by the Western-blot test. Myelopathy was considered associated with HTLV-1 only when the CSF was positive indicating neurotropism of the virus. The mean age of the cases was 44.6 ± 15.6 years and the control group was 43.5 ± 16.0 (p>0.05). An OR of 9.0 was detected with a reability interval (95%) of 1.652-48.866 and chi-square significant at the 0.02 level. Despite a strong degree of association and considering the low level of precision, there is a need for analytical studies with larger samples which besides improving the precision will allow for greater control of the confounding variables.

Translated abstract

Procurou-se determinar a magnitude da associação entre positividade do líquido cefalorraqueano (LCR) para HTLV-1 e mielopatias em Salvador. Foram estudados 28 casos de mielopatias e 28 casos sem doença neurológica, todos procedentes de um único hospital. A seleção foi de modo cego, com pareamento 1:1, por idade e sexo. Os 28 pares realizaram sorologia para HTLV-1 e, nos casos com mielopatia, foram pesquisados anticorpos para HTLV-1 no LCR. Na investigação dos anticorpos foram utilizados os métodos ELISA e Western-blot. Os casos tiveram média de idade de 44,6 ± 15,6 anos e os controles de 43,5 ± 16,0 (p>0,05). Observamos um OR=9,0 com intervalo de confiança 95% de 1,652-48,866 e qui-quadrado significante a 0,02. Apesar do grande nível de associação encontrado, estudos analíticos com associações maisi amplas são necessários com o objetivo de melhorar a precisão e o controle de variáveis intervenientes.