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Evaluation of antibody-ELISA and real-time RT-PCR for the diagnosis and profiling of bluetongue virus serotype 8 during the epidemic in Belgium in 2006
No full textIn 2006 bluetongue (BT) emerged for the first time in North-Western Europe. Reliable diagnostic tools are essential in controlling BT but data on the diagnostic sensitivity (Se) and specificity (Sp) are often missing. This paper aims to describe and analyse the results obtained with the diagnostics used in Belgium during the 2006 BT crisis. The diagnosis was based on a combination of antibody detection (competitive ELISA, cELISA) and viral RNA detection by real-time RT-PCR (RT-qPCR). The performance of the cELISA as a diagnostic tool was assessed on field results obtained during the epidemic and previous surveillance campaigns. As the infectious status of the animals is unknown during an epidemic, a Bayesian analysis was performed. Both assays were found to be equally specific (RT-qPCR: 98.5%; cELISA: 98.2%) while the diagnostic sensitivity of the RT-qPCR (99.5%) was superior to that of the cELISA (87.8%). The assumption of RT-qPCR as standard of comparison during the bluetongue virus (BTV) epidemic proved valid based on the results of the Bayesian analysis. A ROC analysis of the cELISA, using RT-qPCR as standard of comparison, showed that the cut-off point with the highest accuracy occurred at a percentage negativity of 66, which is markedly higher than the cut-off proposed by the manufacturer. The analysis of the results was further extended to serological and molecular profiling and the possible use of profiling as a rapid epidemiological marker of the BTV in-field situation was assessed. A comparison of the serological profiles obtained before, during and at the end of the Belgian epidemic clearly showed the existence of an intermediate zone which appears soon after BTV (re)enters the population. The appearance or disappearance of this intermediate zone is correlated with virus circulation and provides valuable information, which would be entirely overlooked if only positive and negative results were considered
Lack of effectiveness of cellulose sulfate gel for the prevention of vaginal HIV transmission
No full textBackground
Women make up more than 50% of adults living with human immunodeficiency virus
(HIV) infection or the acquired immunodeficiency syndrome (AIDS) in sub-Saharan
Africa. Thus, female-initiated HIV prevention methods are urgently needed.
Methods
We performed a randomized, double-blind, placebo-controlled trial of cellulose sulfate,
an HIV-entry inhibitor formulated as a vaginal gel, involving women at high
risk for HIV infection at three African and two Indian sites. The primary end point
was newly acquired infection with HIV type 1 or 2. The secondary end point was newly
acquired gonococcal or chlamydial infection. The primary analysis was based on a
log-rank test of no difference in the distribution of time to HIV infection, stratified
according to site.
Results
A total of 1398 women were enrolled and randomly assigned to receive cellulose
sulfate gel (706 participants) or placebo (692 participants) and had follow-up HIV test
data. There were 41 newly acquired HIV infections, 25 in the cellulose sulfate group
and 16 in the placebo group, with an estimated hazard ratio of infection for the cellulose
sulfate group of 1.61 (P = 0.13). This result, which is not significant, is in contrast
to the interim finding that led to the trial being stopped prematurely (hazard
ratio, 2.23; P = 0.02) and the suggestive result of a preplanned secondary (adherencebased)
analysis (hazard ratio, 2.02; P = 0.05). No significant effect of cellulose sulfate
as compared with placebo was found on the risk of gonorrheal infection (hazard
ratio, 1.10; 95% confidence interval [CI], 0.74 to 1.62) or chlamydial infection (hazard
ratio, 0.71; 95% CI, 0.47 to 1.08).
Conclusions
Cellulose sulfate did not prevent HIV infection and may have increased the risk of
HIV acquisition. (ClinicalTrials.gov number, NCT00153777; and Current Controlled
Trials number, ISRCTN95638385.
Vector control in a highland province of Burundi: towards a targeted strategy for the prevention of malaria in African highlands
No full textA community effectiveness trial of strategies promoting intermittent preventive treatment with sulphadoxine-pyrimethamine in pregnant women in rural Burkina Faso
No full textBackground: Intermittent preventive treatment with sulphadoxine-pyrimethamine for pregnant
women (IPTp-SP) is currently being scaled up in many countries in sub-Saharan Africa. Despite high
antenatal clinic (ANC) attendance, coverage with the required two doses of SP remains low. The
study investigated whether a targeted community-based promotion campaign to increase ANC
attendance and SP uptake could effectively improve pregnancy outcomes in the community.
Methods: Between 2004 and 2006 twelve health centres in Boromo Health District, Burkina Faso
were involved in this study. Four were strategically assigned to community promotion in addition
to IPTp-SP (Intervention A) and eight were randomly allocated to either IPTp-SP (Intervention B)
or weekly chloroquine (Control). Primi- and secundigravidae were enrolled at village level and thick
films and packed cell volume (PCV) taken at 32 weeks gestation and at delivery. Placental smears
were prepared and newborns weighed. Primary outcomes were peripheral parasitaemia during
pregnancy and at delivery, placental malaria, maternal anaemia, mean and low birth weight.
Secondary outcomes were the proportion of women with ≥ 3 ANC visits and ≥ 2 doses of SP.
Intervention groups were compared using logistic and linear regression with linearized variance
estimations to correct for the cluster-randomized design.
Results: SP uptake (≥ 2 doses) was higher with (Intervention A: 70%) than without promotion
(Intervention B: 49%) (OR 2.45 95%CI 1.25–4.82 p = 0.014). Peripheral (33.3%) and placental
(30.3%) parasite rates were significantly higher in the control arm compared to Intervention B
(peripheral: 20.1% OR 0.50 95%CI 0.37–0.69 p = 0.001; placental: 20.5% OR 0.59 95%CI 0.44–0.78
p = 0.002) but did not differ between Intervention A (17.4%; 18.1%) and Intervention B (20.1;
20.5%) (peripheral: OR 0.84 95%CI 0.60–1.18 p = 0.280; placental: OR 0.86 95%CI 0.58–1.29 p =0.430). Mean PCV and birth weight and prevalence of anaemia and low birth weight did not differ
between study arms.
Conclusion: The promotional campaign resulted in a major increase in IPTp-coverage, with two
thirds of women at delivery having received ≥ 2 SP. Despite lower prevalence of malaria infection
this did not translate into a significant difference in maternal anaemia or birth weight. This data
provides evidence that, as with immunization programmes, extremely high coverage is essential for
effectiveness. This critical threshold of coverage needs to be defined, possibly on a regional basis
Rapid and inexpensive detection of multidrug-resistant Mycobacterium tuberculosis with the nitrate reductase assay using liquid medium and direct application to sputum samples
No full textFor rapid and low-cost detection of multidrug-resistant (MDR) Mycobacterium tuberculosis, we applied the nitrate reductase assay (NRA) using a liquid medium directly to sputum samples. A total of 179 sputum samples were analyzed by the NRA, and results were compared to those obtained by the indirect proportion method (IPM) as a standard reference. Out of 144 specimens for which comparable results were available, only one discrepant result was obtained: MDR by NRA but susceptible by the IPM. In total 56% of the results were obtained in 10 days by the NRA. NRA performed in liquid medium is rapid and inexpensive and can be easily implemented in low-income countries
A simplified and standardized polymerase chain reaction format for the diagnosis of leishmaniasis
No full textBackground. Definite diagnosis of Leishmania infections is based on demonstration of the parasite by microscopic analysis of tissue biopsy specimens or aspirate samples. However, microscopy generally shows low sensitivity and requires invasive sampling.
Methods. We describe here the development of a simple and rapid test for the detection of polymerase chain reaction–amplified Leishmania DNA. A phase 1 evaluation of the text was conducted in clinical samples from 60 nonendemic and 45 endemic control subjects and from 44 patients with confirmed cutaneous leishmaniasis (CL), 12 with mucocutaneous leishmaniasis (MCL), and 43 with visceral leishmaniasis (VL) from Peru, Kenya, and Sudan.
Results. The lower detection limits of the assay are 10 fg of Leishmania DNA and 1 parasite in 180 μL of blood. The specificity was 98.3% (95% confidence interval [CI], 91.1%–99.7%) and 95.6% (95% CI, 85.2%–98.8%) for nonendemic and endemic control samples, respectively, and the sensitivity was 93.2% (95% CI, 81.8%–97.7%), 91.7% (95% CI, 64.6%–98.5%), and 86% (95% CI, 72.7%–93.4%) for lesions from patients with CL or MCL and blood from patients with VL, respectively.
Conclusions. The Leishmania OligoC-TesT showed high specificity and sensitivity in clinical samples and was able to detect the parasite in samples obtained by less invasive means, such as blood, lymph, and lesion scrapings. The assay is a promising new tool for simplified and standardized molecular detection of Leishmania parasites
Co-occurrence of fumonisins with aflatoxins in home-stored maize for human consumption in rural villages of Tanzania
No full textThis study determined maize-user practices that influence the presence of fumonisin and aflatoxin contamination of maize in food consumed in the rural areas of Tanzania. Samples of the 2005 maize harvest in Tanzania were collected from 120 households and examined for fumonisins and aflatoxins. Information on whether the maize was sorted to remove defective (visibly damaged or mouldy) maize before storage and whether the damaged and mouldy maize or the non-dehulled maize was used as food was also collected. In addition, the percentage of defective kernels in the samples was determined. Ninety per cent of the households sorted out defective maize, 45% consumed the defective maize and 30% consumed non-dehulled maize. In 52% of the samples fumonisins were determined at levels up to 11,048 µg kg-1 (median = 363 µg kg-1) and in 15% exceeded 1000 µg kg-1; the maximum tolerable limit (MTL) for fumonisins in maize for human consumption in other countries. Aflatoxins were detected in 18% of the samples at levels up to 158 µg kg-1 (median = 24 µg kg-1). Twelve per cent of the samples exceeded the Tanzanian limit for total aflatoxins (10 µg kg-1). Aflatoxins co-occurred with fumonisins in 10% of the samples. The percentage defective kernels (mean = 22%) correlated positively (r = 0.39) with the fumonisin levels. Tanzanians are at a risk of exposure to fumonisins and aflatoxins in maize. There is a need for further research on fumonisin and aflatoxin exposure in Tanzania to develop appropriate control strategies
