Evaluation of a rapid human Immunodeficiency virus test at two community clinics in Kwazulu-Natal

Objectives. To establish whether the Determine (Abbott, Tokyo, Japan) HIV antibody test is suitable as an on-site rapid HIV test at primary health care centres by determining its sensitivity and specificity compared with the standard enzyme-linked immunoassay (ELISA) test. Design. Prospective field evaluation study of a rapid HIV test compared with an ELISA. Setting. KwaDabeka clinic and StMary's Hospital, urban primary health care clinics in the Durban western metropolitan area. Subjects. Women attending antenatal clinics and those presenting at onset of labour. Outcome measures. Performance of the rapid test versus conventional ELISA testing, sensitivity; specificity, feasibility of implementing the test at primary health care clinics, prevalence of HIV infection at study sites and its association with patient booking status. Results. A total of 323 specimens were tested from patients from two community clinics, KwaDabeka (N = 159) and St Mary's (N = 164). The overall HIV prevalence was 45.5%. There was a significant difference in HIV prevalence (P < 0.001) between KwaDabeka (35.2%) and St Mary's (55.5%). Of the participants 49.2% were from KwaDabeka clinic and 50.8% from StMary's Hospital. Overall, HIV prevalence among unbooked participants was 43.0%, and among booked participants 46.3%. This was not statistically different (P = 0.612) between the two clinics. The rapid test showed a sensitivity and specificity of 100% when compared with a conventional diagnostic ELISA test. Conclusion. The Determine rapid HIV antibody test is sensitive, specific, easy to perform and provides a valuable method for HIV testing especially in settings with limited access to laboratory infrastructures and trained laboratory staff

Formation of the Black Hole in Nova Scorpii

Israelian et al. (1999) showed that the stellar companion of the black-hole binary Nova Sco is polluted with material ejected in the supernova that accompanied the formation of the black-hole primary. Here we systematically investigate the implications of these observations for the black-hole formation process. Using a variety of supernova models, including both standard as well as hypernova models (for different helium-star masses, explosion energies, and explosion geometries) and a simple model for the evolution of the binary and the pollution of the secondary, we show that most of the observed abundance anomalies can be explained for a large range of model parameters (apart from the abundance of Ti). The best models are obtained for He star masses of 10 to 16 Msun, where spherical hypernova models are generally favoured over standard supernova ones. Aspherical hypernova models also produce acceptable fits, provided there is extensive lateral mixing. All models require substantial fallback and that the fallback material either reached the orbit of the secondary or was mixed efficiently with material that escaped. The black hole therefore formed in a two-step process, where the initial mass of the collapsed remnant was increased substantially by matter that fell back after the initial collapse. This may help to explain the high observed space velocity of Nova Sco either because of a neutrino-induced kick (if a neutron star was formed first) or by asymmetric mass ejection in an asymmetric supernova explosion.Comment: 16 pages, 3 Figures, 4 Tables. submitted to Ap

Dried blood spots as a source of anti-malarial antibodies for epidemiological studies

BACKGROUND: Blood spots collected onto filter paper are an established and convenient source of antibodies for serological diagnosis and epidemiological surveys. Although recommendations for the storage and analysis of small molecule analytes in blood spots exist, there are no published systematic studies of the stability of antibodies under different storage conditions. METHODS: Blood spots, on filter paper or glass fibre mats and containing malaria-endemic plasma, were desiccated and stored at various temperatures for different times. Eluates of these spots were assayed for antibodies against two Plasmodium falciparum antigens, MSP-119 and MSP2, and calculated titres used to fit an exponential (first order kinetic) decay model. The first order rate constants (k) for each spot storage temperature were used to fit an Arrhenius equation, in order to estimate the thermal and temporal stability of antibodies in dried blood spots. The utility of blood spots for serological assays was confirmed by comparing antibodies eluted from blood spots with the equivalent plasma values in a series of samples from North Eastern Tanzania and by using blood spot-derived antibodies to estimate malaria transmission intensity in this site and for two localities in Uganda. RESULTS: Antibodies in spots on filter paper and glass fibre paper had similar stabilities but blood was more easily absorbed onto filter papers than glass fibre, spots were more regular and spot size was more closely correlated with blood volume for filter paper spots. Desiccated spots could be stored at or below 4 degrees C for extended periods, but were stable for only very limited periods at ambient temperature. When desiccated, recoveries of antibodies that are predominantly of IgG1 or IgG3 subclasses were similar. Recoveries of antibodies from paired samples of serum and of blood spots from Tanzania which had been suitably stored showed similar recoveries of antibodies, but spots which had been stored for extended periods at ambient humidity and temperature showed severe loss of recoveries. Estimates of malaria transmission intensity obtained from serum and from blood spots were similar, and values obtained using blood spots agreed well with entomologically determined values. CONCLUSION: This study has demonstrated the suitability of filter paper blood spots paper for collection of serum antibodies, and provided clear guidelines for the treatment and storage of filter papers which emphasize the importance of desiccation and minimisation of time spent at ambient temperatures. A recommended protocol for collecting, storing and assaying blood spots is provided

Effects of introducing Xpert MTB/RIF test on multi-drug resistant tuberculosis diagnosis in KwaZulu-Natal South Africa.

CAPRISA, 2014.Abstract available in pdf