A Research Agenda for Helminth Diseases of Humans: The Problem of Helminthiases

Abstract

A disproportionate burden of helminthiases in human populations occurs in marginalised, low-income, and resource-constrained regions of the world, with over 1 billion people in developing areas of sub-Saharan Africa, Asia, and the Americas infected with one or more helminth species. The morbidity caused by such infections imposes a substantial burden of disease, contributing to a vicious circle of infection, poverty, decreased productivity, and inadequate socioeconomic development. Furthermore, helminth infection accentuates the morbidity of malaria and HIV/AIDS, and impairs vaccine efficacy. Polyparasitism is the norm in these populations, and infections tend to be persistent. Hence, there is a great need to reduce morbidity caused by helminth infections. However, major deficiencies exist in diagnostics and interventions, including vector control, drugs, and vaccines. Overcoming these deficiencies is hampered by major gaps in knowledge of helminth biology and transmission dynamics, platforms from which to help develop such tools. The Disease Reference Group on Helminths Infections (DRG4), established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR), was given the mandate to review helminthiases research and identify research priorities and gaps. In this review, we provide an overview of the forces driving the persistence of helminthiases as a public health problem despite the many control initiatives that have been put in place; identify the main obstacles that impede progress towards their control and elimination; and discuss recent advances, opportunities, and challenges for the understanding of the biology, epidemiology, and control of these infections. The helminth infections that will be discussed include: onchocerciasis, lymphatic filariasis, soil-transmitted helminthiases, schistosomiasis, food-borne trematodiases, and taeniasis/cysticercosis.

Giardia intestinalis infection associated with malnutrition in children living in northeastern Brazil

“…These techniques are time consuming and labor intensive; however, they provide valuable information because they can detect protozoan cysts and are thus the gold standard for intestinal protozoa diagnosis. Typically, parasitological surveys aiming to characterize the prevalence rates of STHs employ the Kato-Katz smear, which is operationally more convenient [29]. Therefore, not only are mass treatments more difficult for intestinal protozoa, but accurate diagnoses of these protozoa are also more complicated, meaning that it is extremely difficult to characterize the prevalence rates in different regions.…”

Intestinal parasites in cancer patients in the South of Brazil

“…Despite sanitation improvement and hygiene education in recent decades, these infections continue to be characterized as a major cause of morbidity worldwide (Lustigman et al, 2012). In immunocompromised individuals, such agents are recognized as important enteric pathogens, and may lead to fatal complications (Marcos and Gotuzzo, 2013).…”

Spatial analysis and risk mapping of soil-transmitted helminth infections in Brazil, using Bayesian geostatistical models

“…The distribution of infections is governed by social-ecological systems with poverty playing a key role in maintaining high levels of endemicity. Indeed, the highest rates and intensity of infection and public health burden are concentrated in poor communities in tropical and subtropical areas (de Silva et al, 2003;Tchuem Tchuenté, 2011;Lustigman et al, 2012;Ziegelbauer et al, 2012). The highest infection intensities are usually observed in schoolaged children, whilst there is a decline in prevalence and intensity of infection with age (Anderson and May, 1985;de Silva et al, 2003;Bethony et al, 2006;Brooker et al, 2007).…”