Epidemiology of soil-transmitted nematode infections in Ha Nam Province, Vietnam.

Baseline epidemiological data are presented from a parasitological survey conducted in Thuy Loi commune, Ha Nam province, Vietnam; a farming community where night soil is routinely used as fertilizer for crops. 177 households were visited and 543 individuals (aged 1-88 years) recruited to the study. Helminth infection intensity was assessed by Kato-Katz to determine the density of parasite eggs per gram of stool (epg).

Predicting the impact of school-based treatment for urinary schistosomiasis given by the Ghana Partnership for Child Development.

Mathematical models can be used to predict the impact of interventions to control infectious diseases. In this paper, an epidemiological model is used to predict the impact of chemotherapy of school-age children infected with Schistosoma haematobium, in a programme conducted by the Ghana Partnership for Child Development in the Volta Region, Ghana. Existing data were used to validate the predictions of the model, demonstrating convincingly the ability of the model to make correct predictions.

Can we deworm this wormy world?

While programmes such as the Rockefeller campaign were specifically targeted at a particular parasite species, the current trend is towards the simultaneous control of all the major geohelminth species. New, broad-spectrum, low-cost anthelmintics and new understanding of epidemiology have led to more cost-effective and sustainable strategies. The WHO, UNICEF and the World Bank all now support global and regional efforts to achieve control of morbidity from intestinal worms.

Antigenic variability in Trichuris trichiura populations.

The present study examines antigenic variability for the human whipworm Trichuris trichiura. Recognition by IgG of somatic antigens of individual worms collected from 3 intensely infected children from Jamaica, West Indies has been investigated by immunoblotting. When probed with 1 plasma sample, significant differences in recognition of 2 selected antigens among worm populations and between male and female worms was observed.

Epifil: a dynamic model of infection and disease in lymphatic filariasis.

The lack of a quantitative framework that describes the dynamic relationships between infection and morbidity has constrained efforts aimed at the community-level control of lymphatic filariasis. In this paper, we describe the development and validation of EPIFIL, a dynamic model of filariasis infection intensity and chronic disease. Infection dynamics are modeled using the well established immigration-death formulation, incorporating the acquisition of immunity to infective larvae over time.

Molecular and functional characterization of a recombinant protein of Trichuris trichiura.

The pore-forming protein of the human whipworm, Trichuris trichiura, has been postulated to facilitate invasion of the host gut and enable the parasite to maintain its syncytial environment. The data presented here describe the first, to our knowledge, molecular characterization of a pore-forming protein in any helminth and provide a unique demonstration of the functional interaction between a parasite antigen and host molecules. Immunological screening of a T.

Herd immunity to filarial infection is a function of vector biting rate.

Despite the existence of an impressive body of work on human immune responses against filarial infections, the occurrence of a protective response to infection remains unclear. Here, we use a combined modelling and comparative data analysis framework to address this issue for human infections with the filarial parasite, Wuchereria bancrofti. By analogy with previous work, the analysis involves the comparison of observed field patterns of infection with epidemiological patterns predicted by a mathematical model of parasite immunity.

Wuchereria bancrofti microfilaraemia in children in relation to parental infection status.

A total of 946 families with 2302 children was surveyed for microfilaraemia due to Wuchereria bancrofti. The prevalence of microfilaraemia among offspring born to microfilaraemic parents was significantly higher than in those born to amicrofilaraemic parents (P = 0.0049; relative risk = 3.

The relationship between prevalence of Schistosoma haematobium infection and different morbidity indicators during the course of a control programme on Pemba Island.

A long-term schistosomiasis control programme was initiated on Pemba Island, Tanzania in 1986 with the aim of eliminating morbidity due to Schistosoma haematobium infection. The programme used haematuria as a community indicator of morbidity for surveillance and for identifying individuals for selective population chemotherapy. Analysis of the first 3 evaluation studies showed that the prevalence of microhaematuria was linearly related to the prevalence of infection, and that visually detectable haematuria was a marker of the intensity of infection and risk of morbidity in a community.

Associations among multiple geohelminth species infections in schoolchildren from Pemba Island.

In order to estimate the potential benefits of interventions against multiple geohelminth species in endemic areas, an improved understanding of the population biology of multiple infections is required. This paper presents a detailed analysis of the associations among Ascaris lumbricoides, Trichuris trichiura and hookworm infections in 1539 schoolchildren on Pemba Island, Tanzania, where 58% of the sampled children carried infections of all 3 parasites at the time of the study. Infection intensities of different species were positively correlated, and individuals with single-species infections had generally lower species-specific egg counts than individuals with multiple-species infections.

Modelling variability in lymphatic filariasis: macrofilarial dynamics in the Brugia pahangi--cat model.

A striking feature of lymphatic filariasis is the considerable heterogeneity in infection burden observed between hosts, which greatly complicates the analysis of the population dynamics of the disease. Here, we describe the first application of the moment closure equation approach to model the sources and the impact of this heterogeneity for macrofilarial population dynamics. The analysis is based on the closest laboratory equivalent of the life cycle and immunology of infection in humans--cats chronically infected with the filarial nematode Brugia pahangi.

Humoral responses in human strongyloidiasis: correlations with infection chronicity.

Strongyloides stercoralis L3-specific antibody isotype responses amongst individuals with known long-standing (28-46 years) infection were compared with those of 'young' (6-29 years of age) and 'old' (30-80 years of age) infected individuals from an endemic Jamaican population. Characterization of age-dependent isotype patterns in the endemic community showed that immunoglobulin (Ig) G1 responses were significantly inversely correlated with age. Additionally, a trend towards lower IgE levels in the older age group was observed.

Transmission patterns and the epidemiology of hookworm infection.

Background: This paper presents a suite of models of hookworm transmission dynamics which vary the mixing patterns and rates of contamination and infection between children and adults. In this context mixing refers to the degree of epidemiological communication between children and adults, for example, whether adults are likely to get infected from infective material passed by children.

Methods: Three models are described which represent random mixing, no mixing and restricted mixing respectively.

Diverse effects of BCL3 phosphorylation on its modulation of NF-kappaB p52 homodimer binding to DNA.

IkappaB proteins control the subcellular localization and DNA binding activity of NF-kappaB transcription factors. BCL3 is a nuclear IkappaB that can inhibit or enhance the binding of NF-kappaB p50 or p52 homodimers to consensus DNA-binding (kappaB) sequences or form a kappaB-binding complex with homodimers. To study BCL3 function, we have used gel shift analysis and tagged protein and tagged DNA coprecipitation analyses.

The reliability of self-reported blood in urine and schistosomiasis as indicators of Schistosoma haematobium infection in school children: a study in Muheza District, Tanzania.

The use of self-reported blood in urine and schistosomiasis by school children was investigated as a tool to estimate the prevalence of infection with Schistosoma haematobium and to identify infected individuals. A general questionnaire about common health problems, including questions about blood in urine and schistosomiasis, was administered by teachers to 25443 children in 137 primary schools in Muheza District, Tanzania. The prevalence of reported schistosomiasis was calculated for each school and used to select 15 schools across a range in prevalence.

Human schistosomiasis: potential long-term consequences of vaccination programmes.

Fields trials of new schistosomiasis vaccines are anticipated within the next few years, but there remains great uncertainty regarding the optimal design of vaccination programmes. Mathematical models are used here to explore the potential long-term consequences of vaccination, assuming that the vaccines provide partial protection for a limited period. The analysis suggests that vaccines acting to reduce infection rates or egg output will have a similar impact on levels of infection, that this impact may be highly sensitive to the duration as well as the degree of protection, that it may take several decades for the full impact to become apparent, and that one consequence will be peak levels of infection occurring in older age classes.

Morbidity and mortality due to ascariasis: re-estimation and sensitivity analysis of global numbers at risk.

This paper presents estimates of the global numbers of people at risk from morbidity related to infection with Ascaris lumbricoides and the numbers of deaths from this infection. Morbidity is classified into 4 types: deficits in growth and fitness which are contemporaneous with infection, or permanent, overt acute illness of mild to moderate severity, and complications involving hospitalization. The estimation of morbidity is based on theoretical models of parasite distributions developed in previous papers.

Anthelmintics. A comparative review of their clinical pharmacology.

Virtually all the important helminth infections in humans can be treated with one of 5 anthelmintics currently in use: albendazole, mebendazole, diethylcarbamazine, ivermectin and praziquantel. These drugs are vital not only for the treatment of individual infections, but also useful in controlling transmission of the more common infections. This article reviews briefly the pharmacology of these 5 drugs, and then discusses current issues in the use of anthelmintics in the treatment and/or control of soil-transmitted nematode infections, filariasis, onchocerciasis, schistosomiasis (and other trematode infections), neurocysticercosis and hydatidosis.

Modelling the dynamic effects of community chemotherapy on patterns of morbidity due to Schistosoma mansoni.

This paper uses a mathematical framework to predict the long-term consequences of chemotherapy for the age distribution of schistosomiasis morbidity. The framework incorporates a previously validated transmission model, which is here extended to capture effects on 2 forms of Schistosoma mansoni morbidity: early disease exemplified by hepatomegaly and late disease exemplified by Symmer's fibrosis. The main aim of this analysis is to show how such an approach could be used to explore the probable public health consequences of decades of control.

Worm burden in intestinal obstruction caused by Ascaris lumbricoides.

Examination of 24 case reports suggests the worm burden in those presenting to hospital with intestinal obstruction is > 60 and is about tenfold higher in fatal cases.

Control of Schistosoma haematobium morbidity on Pemba Island: validity and efficiency of indirect screening tests.

Four indirect screening methods for the detection of Schistosoma haematobium morbidity are compared (history of haematuria, visual haematuria, and microhaematuria at the 1+ and 2+ positivity limit by reagent strips) in terms of their diagnostic performance under conditions of progressive decrease in prevalence of infection, intensity and risk of morbidity as a result of repeated schistosomiasis control programmes on Pemba Island, United Republic of Tanzania. The results show that the sensitivity of a history of haematuria was higher (71%) in children but lower in adults (40%), similar to the findings for visual haematuria in children (60%) and adults (40%) at baseline. However, visual haematuria had a higher specificity, positive predictive value, and efficiency than a history of haematuria in both children and adults.

The design of veterinary vaccination programmes.

The optimal design of a veterinary vaccination programme depends on both the characteristics of the vaccine and the epidemiology of the pathogen or parasite. Relevant vaccine characteristics are the proportion of those vaccinated that are initially protected, the duration of protection and the coverage achieved by the vaccination programme. The most important epidemiological parameter is the basic reproduction number, R0.

Morbidity and mortality due to Ascaris-induced intestinal obstruction.

We examined epidemiological aspects of Ascaris-induced intestinal obstruction (AI-IO) through analysis of published reports on the subject. In 9 studies of > or = 100 patients admitted to hospital due to ascariasis, intestinal obstruction was the single most common complication and accounted for 38-87.5% of all complications (weighted mean 72%).