Other Roundworms

Estimating the sensitivity and specificity of Kato-Katz stool examination technique for detection of hookworms, Ascaris lumbricoides and Trichuris trichiura infections in humans in the absence of a 'gold standard'

The accuracy of the Kato-Katz technique in identifying individuals with soil-transmitted helminth (STH) infections is limited by day-to-day variation in helminth egg excretion, confusion with other parasites and the laboratory technicians' experience. We aimed to estimate the sensitivity and specificity of the Kato-Katz technique to detect infection with Ascaris lumbricoides, hookworm and Trichuris trichiura using a Bayesian approach in the absence of a 'gold standard'. Data were obtained from a longitudinal study conducted between January 2004 and December 2005 in Samar Province, the Philippines. Each participant provided between one and three stool samples over consecutive days. Stool samples were examined using the Kato-Katz technique and reported as positive or negative for STHs. In the presence of measurement error, the true status of each individual is considered as latent data. Using a Bayesian method, we calculated marginal posterior densities of sensitivity and specificity parameters from the product of the likelihood function of observed and latent data. A uniform prior distribution was used (beta distribution: alpha=1, beta=1). A total of 5624 individuals provided at least one stool sample. One, two and three stool samples were provided by 1582, 1893 and 2149 individuals, respectively. All STHs showed variation in test results from day to day. Sensitivity estimates of the Kato-Katz technique for one stool sample were 96.9% (95% Bayesian Credible Interval [BCI]: 96.1%, 97.6%), 65.2% (60.0%, 69.8%) and 91.4% (90.5%, 92.3%), for A. lumbricoides, hookworm and T. trichiura, respectively. Specificity estimates for one stool sample were 96.1% (95.5%, 96.7%), 93.8% (92.4%, 95.4%) and 94.4% (93.2%, 95.5%), for A. lumbricoides, hookworm and T. trichiura, respectively. Our results show that the Kato-Katz technique can perform with reasonable accuracy with one day's stool collection for A. lumbricoides and T. trichiura. Low sensitivity of the Kato-Katz for detection of hookworm infection may be related to rapid degeneration of delicate hookworm eggs with time.

Persistent rectal prolapse in children: sclerotherapy and surgical management

Persistent rectal prolapse is an uncommon but distressing condition in children. Significant controversy exists regarding its surgical management. The aim of this study was to identify a successful management strategy for persistent rectal prolapse in the paediatric population. Records of all children with rectal prolapse treated surgically at Birmingham Children's Hospital between 1995 and 2003 were retrospectively reviewed. Demographic data, clinical presentation, investigations, treatment modality, complications, and outcome were recorded. Inclusion criteria for the study were failure of conservative management leading to operative treatment. An exclusion criterion was cystic fibrosis. A total of 24 patients with persistent rectal prolapse were identified. Two children with cystic fibrosis were excluded from the analysis. Children below the age of 5 years, group I (n=17), were successfully managed by submucous hypertonic saline injections. Eighty-three percent (14/17) were cured by injection sclerotherapy in this group, 12/14 (71%) requiring one injection and 2/14 requiring a second injection. In the three (17.6%) children in group I in whom sclerotherapy failed, cow's milk protein (CMP) allergy was identified as the causative factor. Children older than 5, group II (n=5), either had behavioural problems (n=3) or were autistic (n=2). This group of children with adult-type, full-thickness rectal prolapse were found to be refractory to initial attempts of injection sclerotherapy. All five children were successfully managed with surgical correction. We conclude that rectal submucous hypertonic saline injections are highly effective for managing early-onset idiopathic childhood rectal prolapse. CMP allergy should be considered in young children with recurrent rectal prolapse. We recommend early definitive corrective surgery in older children with persistent rectal prolapse, as they do not respond to conservative measures or injection sclerotherapy.

Gastrointestinal parasitic infection, anthropometrics, nutritional status, and physical work capacity in Colombian boys

This article tests the hypothesis that the presence of gastrointestinal parasites in Colombian boys is negatively associated with anthropometric characteristics, physical work capacity, blood hemoglobin (Hb) levels, and nutritional status. Anthropometric, Hb, &Vdot;O(2) max, and parasite load data were collected on 1,016 boys in Cali, Colombia. The boys were classified as lower socioeconomic class (SEC) from either urban or rural environments, and upper SEC from an urban environment. Sixty-three percent of the boys were infected with gastrointestinal parasites and, of the infected boys, 80-95% had light parasite loads. Parasites found included Necator americanus, Ascaris lumbricoides, Entamoeba histolytica, Trichuris trichiura, Giardia spp., and Enterobius vermicularis. Infected boys had significantly lower weight, stature, weight-for-height (among 6-9-year-old boys), Hb levels, and &Vdot;O(2) max (ANCOVA, controlling for age and SEC). In terms of nutritional status, infected boys were 1.47 times more likely to be classified as iron deficient than noninfected boys (chi-square, P < 0.001), and 1.61 times more likely to be classified as stunted (P < 0.001). Infection was not associated with wasting in any SEC group. In conclusion, light to moderate gastrointestinal parasite loads were associated with significantly lower weight, stature, weight-for-height (in 6-9-year-old boys), Hb levels, and &Vdot;O(2) max, and a significantly higher frequency of IDA and stunting. These data suggest that comprehensive analyses of the nutritional status of populations in regions endemic for parasitic infection should include testing for the presence of infection. Am. J. Hum. Biol. 11:763-771, 1999. Copyright 1999 Wiley-Liss, Inc.