Intestinal parasitic infections in pre-school children in the Niger Delta

Stool specimens from 1,062 pre-school children in the Niger Delta were examined for the presence of intestinal parasites. Of that number, 77.6% harboured one or more than one species of intestinal parasites. Ascaris lumbricoides (51.9%) and Trichuris trichiura (41.7%) were the most prevalent species recorded. Other parasites harboured by these children included Hymenolepis sp. (18.3%), Giardia lamblia (9.2%), Entamoeba histolytica (4.6%), Strongyloides stercoralis (1.4%). Hookworm, Taenia sp., Isospora sp. and Trichostrongylus sp. occurred in less than 1% of the children examined. These high rates of infection are associated with poor sanitary conditions prevalent in the area. Improvement of environmental sanitation is advised to reduce human sufferings caused by parasites in that area particularly among children.     

Intestinal parasitic infections in an industrialized country; a new focus on children with better DNA-based diagnostics

In recent years, the isolation of parasitic DNA from faecal samples and PCR techniques, have been improved and simplified. Moreover, the introduction of real-time PCR has made it possible to multiplex different targets into one reaction. These new technical possibilities make it feasible to introduce PCR with its unsurpassed sensitivity and specificity in a routine laboratory setting for the diagnosis of intestinal parasites. Detection rates of the parasitic infections included in the PCR are increased significantly compared with microscopy. Molecular diagnostics, especially in children, reveal a possible cause of the gastrointestinal complaints in many more cases compared with conventional methods. Usually in GP patients no other pathogenic parasites are detected using microscopy and in the returning travellers additional parasites are found with microscopy in a minority of cases only. Multiplex real-time PCR offers a highly sensitive and specific diagnostic alternative for labour intensive microscopy in clinical laboratory practice. Additional diagnostic methods for the detection of parasitic infections that are not included as PCR target can be limited to a selected group of patients.     

Intestinal parasitic infections in homosexual men: prevalence,symptoms and factors in transmission.

In a controlled study 67.5% of 200 homosexual men but only 16% of 100 heterosexual men were found to be infected with intestinal parasites. Entamoeba histolytica was isolated from 27% of the homosexual and 1% of the heterosexual men, and Giardia lamblia was isolated from 13% of the homosexual and 3% of the heterosexual men. The presence of symptoms could not be correlated with infection except when the infection was caused by more than one organism, including G. lamblia. Symptoms were much more common in both infected and uninfected homosexuals than in heterosexuals. Among the homosexual men recent foreign travel, living in a homosexual household and promiscuity were not correlated with intestinal parasitic infection, but cleansing of the anus before and sex was associated with a significantly lower prevalence of infection. These findings suggest that the male homosexual community may be an important reservoir of potentially pathogenic protozoa.     

Intestinal parasitic infections and risk factors for infection in Kenyan children with and without HIV infection

It has been reported that HIV infection is not a risk factor for Entamoeba species infection but is for Giardia intestinalis assemblage B in children living in Western Kenya. This study aimed to investigate the prevalence of and the risk factors for Entamoeba spp. and G. intestinalis infection in children living in Nairobi, Kenya. This cross-sectional study included 87 children with HIV [HIV(+)] and 85 without HIV [HIV(−)]. Stool and blood samples were collected for the detection of the parasites by PCR and immunological analyses using flow cytometry. Sociobehavioral and hygienic data were collected using questionnaires and analyzed statistically. The prevalence of Entamoeba spp. infection was significantly lower in the HIV(+) than in the HIV(−) children (63.2% vs. 78.8%, P = 0.024), whereas the prevalence of G. intestinalis infection was not (27.6% vs. 32.9%, P = 0.445). “Not boiling drinking water” (adjusted odds ratio [aOR]: 3.8, P = 0.044) and “helping in nursery care” (aOR: 2.8, P = 0.009) were related to G. intestinalis assemblage B infection, and “CD4/CD8 ratio ≥1” was related to Entamoeba spp. infection (aOR: 3.3, P = 0.005). In stratified regression analyses, HIV infection was negatively associated with G. intestinalis assemblage B infection in females (aOR: 0.3, P = 0.022), but positively associated in males (aOR 3.8, P = 0.04). These results suggest that G. intestinalis assemblage B infection is related to hygienic conditions, while Entamoeba spp. infection is an indicator of better immunological status, and that the role of HIV infection in Giardia infection may differ between Kenyan boys and girls.     

Genetic control of eosinophilia in parasitic infections: Responses of mouse strains to treatment with cyclophosphamide and parasite antigen

, and 1988. Genetic control of eosinophilia in parasitic infections: responses of mouse strains to treatment with cyclophosphamide and parasite antigen. International Journal for Parasitology18:1077–1085. Strain-dependent variation in the capacity of inbred and congenic mice to mount an eosinophilia in response to inoculation with the antigens of Mesocestoides corti, Trichinella spiralis or with Limulus haemocyanin (LCH), following pretreatment with cyclophosphamide (CY), is described. SWR, NIH, BALB/c, C3H and SJL mice were eosinophil high responder strains whereas C57 BL/10 and CBA mice were eosinophil low responder strains. Congenic strains with the B10 background (B10.S, B10.G and B10.BR) were all low eosinophil responders, although B10.G mice showed a level of response consistently above the other B10 congenic strains. Some of the gene(s) for high responsiveness appeared to be dominant, because F(In1)hybrids between high and low eosinophil response parental strains were intermediate to high responders. The strain-dependent pattern of eosinophil responsiveness to LHC or to M. corti and T. spiralis antigens, following CY pretreatment, was similar to that obtained previously following infection with either M. corti or T. spiralis, suggesting that heterogeneity in capacity to produce eosinophils operates independently of the nature of the eliciting stimulus.     

Antigens and antibodies in parasitic infections

Cells in lettuce and cabbage leaves can readily be separated and observed in the living state by the use of a cheap pectinase enzyme     

Glycomarkers in parasitic infections and allergy

Both helminth infections and contact with allergens result in development of a Th2 type of immune response in the affected individual. In this context, the hygiene hypothesis suggests that reduced prevalence of parasitic infections and successful vaccination strategies are causative for an increase of allergies in industrialized countries. It is therefore of interest to study glycans and their role as immunogenic structures in both parasitic infections and allergies. In the present paper we review information on the different types of glycan structure present in proteins from plant and animal food, insect venom and helminth parasites, and their role as diagnostic markers. In addition, the application of these glycan structures as immunomodulators in novel immunotherapeutic strategies is discussed.     

Immune effector mechanisms in parasitic infections

edited by F.Y. Liew and K. Vickerman, Philosophical Transactions of the Royal Society of London Series B, Vol. 352, No. 1359, 1997. pp 1293-1394, ISSN 0962-8436.