Outstanding insecurities concerning the use of an Ov16-based ELISA in the Amazonia onchocerciasis focus

In a recent issue of Memórias do Instituto Oswaldo Cruz, published in Rio de Janeiro in February 2014 (109: 87-92), Adami et al. have published a survey reporting Mansonella parasite prevalence in the Amazon Region. This report makes a useful contribution to the existing knowledge of filarial parasite distribution within the Amazon area, parasite prevalence rates in relation to age and occupation and provides observations on the possible clinical impact of Mansonella ozzardi. Their publication also provides an account of what appears to be a novel ELISA that has recently been used in the Simuliidae and Onchocerciasis Laboratory of the Oswaldo Cruz Institute, Rio de Janeiro, Brazil. We are concerned that the publication of this ELISA may have created an excessively positive impression of the effectiveness of the onchocerciasis recrudescence serological surveillance tools that are presently available for use in the Amazonia onchocerciasis focus. In this letter we have, thus, sought to highlight some of the limitations of this ELISA and suggest how continuing insecurities concerning the detection of antibodies to Onchocerca volvulus within the Amazonia onchocerciasis focus might be minimised.

Fournier’s Gangrene: A Case of Neglected Symptoms with Devastating Physical Loss

Fournier’s gangrene is a severe life-threatening infection involving the perianal area, perineum, and external genitalia. It demands prompt recognition, critical care therapy, surgical therapy, and a combination of antibiotics. The infection commonly spreads via the fascial planes and causes superficial vascular thrombosis within the Colles’ fascia around the external genitalia. It can extend cephalad to involve the Scarpa’s fascia and Camper’s fascia in the abdominal wall. The treatment would include multiple debridements, which would result in disfiguring scars of the perineum and might lead to significant physical and psychological complications. We describe a case of a 58-years-old man presenting with Fournier’s gangrene resulting from an infection of an impacted urethral stone. The patient previously had obstructive voiding symptoms for 1 month but chose to neglect them. The resultant infection was severe and caused penile and right testicular gangrene. He underwent multiple wound debridements, which included a total penectomy and right orchiectomy. Psychological and rehabilitative support was necessary for him to overcome his loss and disfigurement.

A practical guide for multivariate analysis of dichotomous outcomes

A dichotomous (2-category) outcome variable is often encountered in biomedical research, and Multiple Logistic Regression is often deployed for the analysis of such data. As Logistic Regression estimates the Odds Ratio (OR) as an effect measure, it is only suitable for case-control studies. For cross-sectional and time-to-event studies, the Prevalence Ratio and Cumulative Incidence Ratio can be estimated and easily interpreted. The logistic regression will produce the OR which is difficult to interpret in these studies. In this report, we reviewed 3 alternative multivariate statistical models to replace Logistic Regression for the analysis of data from cross-sectional and time-to-event studies, viz, Modified Cox Proportional Hazard Regression Model, Log-Binomial Regression Model and Poisson Regression Model incorporating the Robust Sandwich Variance. Although none of the models is without flaws, we conclude the last model is the most viable. A numeric example is given to compare the statistical results obtained from all 4 models.