Heavy Trichuris infection and amoebic dysentery in Orang Asli children. A comparison of the two diseases

Iron-modulated virulence factors of Entamoeba histolytica

Entamoeba histolytica is a human parasite that causes amoebiasis, a disease that affects the colon and liver and is prevalent worldwide. This protozoan requires a high concentration of iron to survive and reproduce. Iron modulates the expression of parasite virulence factors, including hemoglobinases, hemoglobin-binding proteins and cysteine proteases, as well as proteins related to the amoebic cytoskeleton. This review summarizes the virulence factors that are affected by iron, resulting in upregulation or downregulation of E. histolytica genes. This review also discusses the functionality of iron in the mechanisms of pathogenesis.

Epidemiology and Genetic Characterization of Noroviruses among Adults in an Endemic Setting, Peruvian Amazon Basin, 2004-2011

Background

Successful vaccination strategies against norovirus will require understanding the burden of disease and relevant genotypes in populations. However, few data are available from cohort studies of adults living in low- and middle-income countries (LMIC).

Materials and Methods

We conducted a nested case-control study within a Peruvian military cohort to characterize the burden of norovirus infection, predominant genotypes, and associated symptoms from 2004 through 2011. Randomly selected case and control stools were tested for norovirus, bacteria, and parasites. The odds ratio of the association between norovirus infection and diarrhea was estimated using multiple logistic regression and co-infection adjusted attributable fractions were calculated.

Results

Of the 3,818 cohort study participants, 624 developed diarrhea. Overall and norovirus-associated diarrhea incidence rates were 42.3 and 6.0 per 100 person-years, respectively. The most prevalent norovirus genogroup was GII (72.5%, 29/40), which was associated with diarrhea (AOR 3.4, 95% CI: 1.3–8.7, P = 0.012). The co-infection adjusted GII attributable fraction was 6.4%.

Discussion

Norovirus was a frequent cause of diarrhea in an adult population followed longitudinally in an LMIC setting. Vaccine strategies should consider targeting adults in endemic settings and special populations that could serve as community transmission sources.

Trichuris trichiura in a post-Colonial Brazilian mummy

Trichuris trichiura is a soil-transmitted helminth which is prevalent in warm, moist, tropical and subtropical regions of the world with poor sanitation. Heavy whipworm can result either in Trichuris dysenteric syndrome - especially in children - or in a chronic colitis. In heavy infections, worms can spread proximally and may cause ileitis. Here we provide first microscopic evidence for a T. trichiura adult worm embedded in the rectum of a post-Colonial Brazilian adult mummy. During Colonial and post-Colonial times, many European chroniclers described a parasitic disease named Maculo whose symptomatology coincides with heavy helminthiasis. Based on our findings and on comparison of ancient textual evidence with modern description of heavy whipworm, we feel confident in considering that the two syndromes are expressions of the same pathological condition.

Concurrent infections and socioeconomic determinants of geohelminth infection: a community study of schoolchildren in periurban Guinea-Bissau

We explored the association between subclinical intestinal helminth infections and other gastrointestinal pathogens in 706 schoolchildren from a poor semirural area while adjusting for socioeconomic risk factors. The study was carried out in two neighbouring areas in the capital of Guinea-Bissau in West Africa. Children aged 4-12 years were visited and one child per mother was invited to participate in the study. Among the 706 children included in the study, helminths were detected in 44.2%, enteropathogenic bacteria in 13.7%, protozoans in 51.1% and rotavirus in 5.9%. A total of 76.1% had an infection of some sort and 41.8% were concomitantly infected with more than one and up to five gastrointestinal pathogens. After adjustment for possible confounding factors, infection with helminths and Entamoeba histolytica/E. dispar remained associated. Other risk factors for helminths included increasing age, male gender, small mid-upper arm circumference and chicken husbandry. Maternal school attendance and belonging to a Muslim family were associated with a lower prevalence of helminths. Investigations of concomitant infections are valuable as they may have implications for control and treatment strategies.

Two quantitative trait loci influence whipworm (Trichuris trichiura) infection in a Nepalese population

BACKGROUND

Whipworm (Trichuris trichiura) infection is a soil-transmitted helminth infection that affects >1 billion people. It is a serious public health problem in many developing countries and can result in deficits in growth and cognitive development. In a follow-up study of significant heritability for whipworm infection, we conducted the first genome scan for quantitative trait loci (QTL) influencing the heritability of susceptibility to this important parasitic disease.

METHODS

Whipworm egg counts were determined for 1,253 members of the Jirel population of eastern Nepal. All individuals in the study sample belonged to a single pedigree including >26,000 pairs of relatives that are informative for genetic analysis.

RESULTS

Linkage analysis of genome scan data generated for the pedigree provided unambiguous evidence for 2 QTL influencing susceptibility to whipworm infection, one located on chromosome 9 (logarithm of the odds ratio [LOD] score, 3.35; genomewide P = .0138) and the other located on chromosome 18 (LOD score, 3.29; genomewide P = .0159). There was also suggestive evidence that 2 loci located on chromosomes 12 and 13 influenced whipworm infection.

CONCLUSION

The results of this first genome scan for T. trichiura egg counts provides new information on the determinants of genetic predisposition to whipworm infection.

Excretion in feces and mucosal persistence of Salmonellaser. Typhimurium in pigs subclinically infected with Oesophagostomum spp

OBJECTIVE

To determine interactions between Oesophagostomum spp and Salmonella ser. Typhimurium in pigs.

ANIMALS

30 healthy 5- to 6-week-old pigs.

PROCEDURE

Pigs were allotted to 3 groups (n = 10 pigs/group) and treated as follows: group A was given Oesophagostomum dentatum and O quadrispinulatum; group B was given O dentatum, O quadrispinulatum, and S Typhimurium; and group C was given S Typhimurium only. Pigs in groups A and B were trickle infected with Oesophagostomum spp 3 times weekly throughout the study. After 19 days, groups B and C were inoculated once with S Typhimurium. One pig from each group was euthanatized on the day of Salmonella exposure and 2 and 4 days after Salmonella exposure. The remaining pigs were euthanatized on days 16 and 17 after Salmonella exposure.

RESULTS

Pigs with dual infections of nematodes and bacteria (group B) excreted significantly higher amounts of S Typhimurium in feces, compared with nematode-free pigs (group C). In addition, group-B pigs excreted S Typhimurium on more days than pigs in group C. Salmonella Typhimurium was detected in the cecum and colon in the majority of pigs in group B, whereas S Typhimurium was only detected in the colon in pigs in group C. Immunohistochemical examination detected S Typhimurium in 7 of 9 pigs in group B but only 2 of 9 pigs in group C.

CONCLUSIONS AND CLINICAL RELEVANCE

Interactions between intestinal nematodes and bacteria may play an important role in the dynamics of S Typhimurium infections.

Anemia and intestinal parasitic infections in primary school students in Aracaju, Sergipe, Brazil

Anemia is estimated to affect half the school-age children and adolescents in developing countries. The main causes are parasitic infections, malaria, and low iron intake. This study aimed to describe the prevalence of anemia, parasitic infections, and nutritional status of children attending public primary schools in Aracaju, Northeast Brazil. Of 360 students, 26.7% were anemic, and prevalence was higher in children under 8 and over 15 years of age. Overall prevalence of intestinal parasites was 42%, with Ascaris lumbricoides (28.7%), Trichuris trichiura (15.6%), and hookworm (1. 7%) most frequently found. There was an association between parasitic infections and poor sanitary conditions, but there was no association between anemia and presence of intestinal parasites. Height-for-age Z scores were lower than the NCHS standard, and prevalence of stunting was 5.4%. Although intestinal parasites were not associated with anemia, children with parasites had lower nutritional indices (weight- and height-for-age Z scores) than those without parasites.

Rectal prolapse in pediatrics

Rectal prolapse in pediatrics has its highest incidence in infancy and is uncommonly seen in industrialized countries. The prolapse may involve only the mucosa (mucosal prolapse) or all layers of the rectum (complete prolapse or procidentia). It is usually detected by the child's parents and is brought urgently to medical attention; however, it is usually spontaneously reduced by the time they reach the practitioner's office. Rectal prolapse should be viewed as a symptom of an underlying condition rather than a discrete disease entity. Potential causes are increased intraabdominal pressure, diarrheal and neoplastic diseases, malnutrition, and conditions predisposing to pelvic floor weakness. Its strong association with cystic fibrosis makes the sweat test mandatory for infants and children with recurrent rectal prolapse. Of particular importance are three entities related to rectal prolapse that may easily escape diagnosis by practitioner: occult rectal prolapse, solitary ulcer of the rectum syndrome, and inflammatory cloacogenic polyps. The treatment of rectal prolapse is mainly conservative and is directed at the underlying conditions. Surgical intervention may be required for recurrent rectal prolapse refractory to conservative measures. The simplest, less invasive, yet highly effective approach, appears to be perirectal injection with a sclerosing agent. While the majority of children experience spontaneous resolution of the prolapse, the prognosis is worse when presentation occurs after the age of 4 years.

An outbreak of Trichuris trichiura in a mental handicap hospital

An outbreak of Trichuris trichiura in a ward for the severely mentally handicapped affected 22 of 29 patients. There was concurrent carriage of non-pathogenic Entamoeba histolytica in 59% of these patients. Heavy contamination of soil was found in the patients' recreation area. The management of the outbreak is discussed.

Trichuris is not trivial

There is no doubt that whipworm, Trichuris trichiura, is common - infecting up to 800 million people throughout tropical and temperate areas. Less clear has been its clinical significance, largely because of the chronic insidious nature of the disease. Here, Ed Cooper and Don Bundy discuss the scale of disease caused by Trichuris, pointing to possible reasons for its neglect- under-recognition, under-reporting, and/or uncertainty of pathogenesis.

Epidemiological aspects of Trichuris and trichuriasis in Caribbean communities

The review argues for a reappraisal of the health significance of the human whipworm, Trichuris trichiura. Infections with this geohelminth are at least as prevalent as Ascaris lumbricoides in many localities, and are associated with significant morbidity. Infection may result in severe trichuriasis syndrome or, more frequently, in a chronic colitis associated with growth stunting. Under-reporting of the chronic manifestations of disease has resulted in a gross under-estimation of the health impact of trichuriasis. Furthermore, estimation of the population dynamical parameters of T. trichiura transmission suggests that whipworm infections are intrinsically more resistant to control than those of other common geohelminths. A major determinant of the transmission dynamics and morbidity characteristics of this helminthiasis is the aggregation of worm burdens in certain predisposed individuals and age groups. It is suggested that improved understanding of the factors generating this distribution of infection intensity is a pre-requisite for effective control of both infection and morbidity.

Nutritional aspects of infection

Current knowledge is examined about the means whereby ascariasis, hookworm disease, strongyloidiasis and trichuriasis may contribute to the aetiology of human malnutrition. Results from experiments with related parasites in the laboratory have demonstrated the role of gastrointestinal helminthiases in animal malnutrition. Some evidence shows that in children, infection with the intestinal stages of Ascaris lumbricoides is associated with reduced growth rate, disturbed nitrogen balance, malabsorption of vitamin A, abnormal fat digestion, lactose maldigestion and an increased intestinal transit time. The main impact of hookworm infection is its relationship with iron-deficiency anaemia which may have effects at the community level as regards work and productivity in adults and learning and school performance in children. More research is needed to extend knowledge of the nutritional impact of ascariasis and hookworm disease in order to establish their public health significance. Research is needed also to identify the range of nutritional effects on man that occur as a result of trichuriasis and strongyloidiasis. The significance of less prevalent and more localized gastrointestinal helminthiases should not be ignored.

The adverse consequences of heavy Trichuris infection

Sixty-seven children with heavy Trichuris trichiura infection (Group A) were compared to 73 control children of similar socio-economic status but with light or no T. trichiura (Group B), for nutritional status, rates of concomitant bacterial and protozoal, and symptoms and clinical signs associated with heavy T. trichiura infection. Anoscopy was used to determine heavy T. trichiura infection. Measurements and physical examination were done on Group A on admission to and discharge from hospital; 46% were seen on follow-up visit two to eight months later. Children in Group B were seen only once. There were significant differences for nutritional status (p less than 0.01) and rates of bacterial and protozoal co-infection (p less than 0.01) and a significantly greater rate of invasive amoebiasis in Group A. After treatment, nutritional parameters of Group A children improved significantly, symptoms and clinical signs decreased and there was also a significant decrease in the rate of concomitant bacterial and protozoal infection. Subgroups of Group A children, with and without concomitant enteropathogens, revealed that infection with Entamoeba histolytica and bacterial enteropathogens had had no significant impact on clinical and nutritional status.