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Hydranencephaly, the almost complete absence of the cerebral parenchyma, induced by infection with modified live bluetongue virus (BTV) crossing the placenta has previously been reported in sheep and rarely in cattle in the USA and in South Africa. The current study describes 29 cases of hydranencephaly in bovine foetuses and ‘dummy’ calves up to 3 months of age in Belgium associated with natural BTV serotype 8 infection very early in gestation. Histological examination of the remaining cerebral parenchyma showed moderate to severe atrophy of the neural tissue. The lesions observed support the hypothesis of BTV-induced destruction of precursor cells. However, in several calves a slight infiltration of the walls of venules and arterioles with T lymphocytes (vasculitis) was observed as well, which seems to be responsible for at least some of the lesions. Bluetongue viral RNA was detected in 15 animals using a BTV-specific real-time RT-PCR with a much higher success rate in brain tissues compared with blood and spleen samples. Virus isolation in embryonated eggs was unsuccessful. In conclusion, hydranencephaly in calves can be associated with natural wild-type BTV-8 intra-uterine infection. [ABSTRACT FROM AUTHOR]

A total of 152 sera from African subjects were tested for presence of antibody to human immunodeficiency virus using four enzyme immunoassays (EIA) marketed by Abbott Diagnostics, Organon Teknika, Wellcome and Diagnostics Pasteur respectively, an indirect immunofluorescence assay (IFA) and an immunoblot assay (IBA) as reference test. The sensitivity (95% confidence limits, CL) of the EIAs and the IFA ranged between 80.9% and 99.1%. The specificity of the Abbott EIA was lower (95% CL: 38.1-72%) than that of the other assays (95% CL: 83.5-100%). The use of an IFA or the Wellcome competitive EIA as confirmatory test on initially EIA positive sera yielded a specificity of 85.5-100% (95% CL) compared with the IBA. The costs of screening by an EIA, followed by confirmatory testing of reactive sera with IFA or the Wellcome EIA and IBA on discrepant test results was similar for all combinations with the exception of initial screening with the Abbott EIA which was more expensive. Using a limited number of sera from African subjects no one test system yielded a significantly superior degree of specificity or sensitivity.

To define the rate of HIV infection and associated risk factors among heterosexual partners of HIV-infected individuals, 80 partners and 77 index cases were examined for clinical, behavioural and virological variables. The study population included 61 male and 16 female index cases, of whom 40 were European and 37 African. Multiple sexual partners in central Africa was the risk factor for HIV infection in 83%. The overall infection rate among the contact cases was 45%, 53% among female partners and 13% among male partners (P less than 0.001). Variables significantly associated with HIV infection in the partners included advanced clinical stage (AIDS-related complex or AIDS), a low concentration of T4 lymphocytes and African nationality of the index case, young age of the partner, and more than 50 instances of sexual contact with the index cases. In a logistic regression analysis, a low concentration of T4 lymphocytes, clinical stage ARC/AIDS and African nationality of the index case but not number of sexual contacts, remained as independent risk factors for HIV transmission. Our data indicate that there is a significant biological heterogeneity in sexual transmission of HIV and that advanced clinical stage and severe T cell depletion of the index case are major determinants of infectivity.

The performance of two HIV antigen enzyme immunoassays (EIAs), the HTLV-III antigen EIA (Abbott) and the Innotest HIV antigen EIA (Innogenetics), was assessed using 276 HIV-1 antibody positive and 42 HIV antibody negative sera from European and African individuals. On the initial screening 16% (51/318) of the sera were reactive in the Abbott EIA and 21.4% (68/318) in the Innotest EIA. The Innotest detected significantly more confirmed HIV antigen positive sera (55/58, 94.6%) than the Abbott EIA (41/58, 70.7%). The presence of free detectable HIV antigen in African and European sera was strongly associated with the clinical classification CDC IV and with low p24 antibody levels.