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PubMed1984

Implications of parasite-nutrition interactions from a world perspective.

Parasitic intestinal infections are among the most common in Africa, Asia, and Latin America. Although the mortality and morbidity caused by intestinal parasitic infections are relatively low, the absolute number of deaths and cases of disease is rather high in relation to other bacterial and viral infections. Scientific evidence for a causal relationship between intestinal parasitic infections and malnutrition is only fragmentary. The overdispersed frequency distribution of helminth parasites in the human population and the stability of giardiasis in some individuals may help only to define the potential target groups for immediate medical intervention, i.e., those patients heavily parasitized and/or severely malnourished. Long-term preventive intervention should include prenatal control of malnutrition, breast feeding and proper weaning food practices, oral rehydration for acute diarrhea, and immunization and possibly control of parasitic infections. Solid arguments in favor of the latter are expected to emerge from the field studies on intestinal parasitic infections and nutrition designed in 1981 by the World Health Organization and the United Nations Children's Emergency Fund. The results of these studies that will be carried out in several countries should serve as a guide for future parasite control projects and nutritional policies, including supplementary feeding programs.

Intestines↗
PubMed1997

Occurrence of Merogony of Aggregata Frenzel 1885 (Apicomplexa) in Pleoticus muelleri and Artemesia longinaris (Crustacea: Natantia) from Patagonian Waters (Argentina)

The aim of this paper is to describe the merogonic phases of the coccidian Aggregata sp. in the natantians Pleoticus muelleri and Artemesia longinaris from Argentina. Ninety-seven specimens of P. muelleri (from San Jorge Gulf) and 49 of A. longinaris (from Rawson) were examined for intestinal parasites. Intestines were processed under standard histological conditions. The distribution of the octopuses (where gamogony and sporogony of Aggregata spp. take place) in the area considered and the importance of finding these protistans in crustaceans other than brachyurans are also explored. High prevalence values for both hosts indicate that shrimps are the primary hosts for these parasites in Argentinean waters. Copyright 1997 Academic Press. Copyright 1997 Academic Press

Journal Article↗
PubMed2001

Cytokine regulation of resistance and susceptibility to intestinal nematode infection - from host to parasite.

Intestinal nematode infection is one of the most common forms of parasite infection worldwide. Both man and domestic stock suffer considerable morbidity from these infectious agents. The majority of our current understanding of the host parasite relationship to gut dwelling nematodes comes from well-defined laboratory models. One of the most informative over recent years has been study of whipworm infection in the mouse, Trichuris muris (T. muris). Infection in inbred strains of mouse shows a spectrum of response phenotypes reflecting the variation observed under natural conditions in the wild. Resistance and worm expulsion is mediated by CD4+ T helper two cells with a dominant role for interleukin (IL)-13. The effector mechanisms responsible for worm expulsion remain undefined but new evidence suggests a role for tumour necrosis factor alpha (TNF-alpha). Susceptibility to chronic infection is mediated through a T helper 1 (Th1) response characterised through the secretion of interferon gamma (IFN-gamma). A major new role for IL-18 has been defined in induction of a Th1 response through a novel down-regulation of IL-13. Moreover, progression to chronic infection may involve the parasite itself. T. muris secretes a protein that shares epitopes with host IFN-gamma, which may interfere with host protective cytokine, mediated protection and thus, promotes its own survival.

Animals↗
PubMedDate not supplied

Skin manifestations in parasite infection.

BACKGROUND: Intestinal parasites stimulate IgE synthesis by their proteinases. Because of their ability to induce IgE production and mast cell degranulation (either directly, e.g. Ascaris, or via specific IgE) it is possible that some parasites induce allergic manifestations. Some parasites may be more allergenic than others due to their allergenicity. Genetic predisposition, nutritional status, and psychosocial variables of the host and the time and degree of allergen exposure may also play an important role. THE AIM: Of our study was to investigate which parasites are more frequently related to the skin manifestations and if atopic background of the host has a role in these skin allergic hives in intestinal parasites. MATERIAL AND METHOD: 55 patients (13 men, mean age 36 years old) infested with digestive parasites were skin prick tested to inhalant allergens (house dust mites, pollens, animal dander) in order to evaluate the atopic status. All patients had allergic skin manifestations (rash and hives) and angioedema due to their intestinal parasites, which remitted after antiparasitic treatment. RESULTS: Forty (73.3%) patients presented angioedema and 15 patients (26.6%) had chronic rash. Patients who were infected with Ascaris had more severe symptoms: more than 2/3 had angioedema, and only one third had chronic rash. More than 2/3 of the patients were infested with Ascaris lumbricoides: 38 patients (69.09%), and only one third were infested with Giardia lamblia: 18 patients (32.72%). Only one third of the patients (17-30.9%) had positive skin prick tests for at least one inhalant allergen. CONCLUSIONS: The parasite most frequently implicated in skin allergic manifestations in our region is Ascaris lumbricoides. Acute angioedema or chronic rash are the major skin manifestations in parasitic infestation. The atopic trait has no importance in the appearance of allergic manifestations in parasitic infestation.

Adult↗
PubMed2003

Contrasting roles for IL-10 in protective immunity to different life cycle stages of intestinal nematode parasites.

Expulsion of the gastro-intestinal nematode Trichinella spiralis is associated with a pronounced mastocytosis mediated by a T helper (Th) 2 type response involving interleukin (IL)-4 and IL-13. Here we demonstrate that IL-10 is a key regulator of protective immune responses against T. spiralis in vivo. IL-10 knockout mice or normal mice treated with a neutralizing anti-IL-10 receptor antibody are highly susceptible to a primary T. spiralis infection and show significantly delayed adult worm expulsion. Depletion of IL-10 resulted in elevated Th1 and Th2 cytokine responses but significantly reduced numbers of mucosal mast cells in the jejunum. Interestingly, the increase in IFN-gamma detected in the absence of IL-10 resulted in increased immunity to larval stages. Hence, IL-10 has a negative effect on immunity to the tissue dwelling larval stages of T. spiralis but plays a significant biological role as an in vivo regulator of intestinal mast cell responses and is crucially involved in protection against adult stages of intestinal parasites in vivo.

Animals↗
PubMed2005

Histochemistry of glycoconjugates in mucous cells of Salmo trutta uninfected and naturally parasitized with intestinal helminths.

Mucus secreted onto the surface of the intestine forms a physical barrier to invading parasites so that a possible attachment of helminths to the surface is prevented and their expulsion by peristalsis facilitated. In mammals, intestinal parasites induce hyperplasia and hypertrophy of intestine goblet cells and provoke changes in the mucus composition. In fish, this topic has received less attention. In the present investigation, histochemical methods were employed to compose intestinal mucous cell numbers and their glycoconjugate composition were compared by uninfected brown trout Salmo trutta and in S. trutta parasitized with Cyathocephalus truncatus or Pomphorhynchus laevis. When P. laevis was present in the intestine of the brown trout, the total mucous cell number, and the number of mucous cells containing acid or mixed glycoconjugates were significantly enhanced. No significant change in the total mucous cell number was detected in the intestine of fish parasitized with C. truncatus in comparison with uninfected brown trout. A significant increase was observed in the number of both acid (especially sulphated) and mixed glycoconjugates containing mucous cells as well as a significant decrease in the number of neutral glycoconjugates containing mucous cells. When intestinal helminths were present, the thickness of the adherent mucous gel increased. In a limited number of other fish species, the occurrence of gill and intestinal parasites has been reported to increase the mucosal glycoconjugate secretions. Our study is the first quantitative report on the effects of intestinal helminths on the density of mucous cells and mucus composition in a fish species.

Analysis of Variance↗
PubMedDate not supplied

Undiagnosed and potentially lethal parasite infections among immigrants and refugees in Australia.

Intestinal parasite infections are a major cause of ill health in many resource-poor countries. This study compares the types and rates of these infections and their risk factors in recently arrived and long-term immigrants in Australia. Cross-sectional surveys of 127 East African and 234 Cambodian immigrants and refugees were undertaken in 2000 and 2002, respectively, to assess the burden of intestinal parasites and collect demographic information. Serum samples were assessed for eosinophilia and Strongyloides stercoralis and Schistosoma antibodies, and feces examined for ova, cysts, and parasites. Intestinal parasites were identified in 77/117 fecal samples from East African and in 25/204 samples collected from Cambodian participants. Eleven percent (14/124) of East Africans and 42% (97/230) of Cambodians had positive or equivocal serology for S stercoralis. Schistosoma serology was positive or equivocal in 15% (19/124) of East African participants. Potentially serious intestinal parasite infections are common among recent and longer term immigrants despite multiple visits to health care providers. Immigrants and refugees from high-risk countries would benefit from comprehensive health checks soon after resettlement.

Adolescent↗
PubMed2004

Important zoonotic intestinal protozoan parasites in Asia.

Intestinal protozoa are increasingly being studied because of their association with acute and chronic diarrhoea in immunocompromised as well as immunocompetent patients. Various community outbreaks due to contamination of water or food with these protozoa have further highlighted their importance in public health. Among these important pathogens are Giardia duodenalis, Entamoeba histolytica, Cryptosporidium parvum, Cyclospora cayetanensis, Isospora belli, and microsporidia. Except for the cyst-forming G. duodenalis and E. histolytica, the others are intracellular and form spores which are passed out with the faeces. These organisms are also found in various animals and birds and zoonotic transmission is thought to occur. These infections are distributed worldwide, with a higher prevalence in developing compared to developed countries. However, the relative importance of zoonotic infections especially in developing countries has not been studied in detail. The prevalence rates are generally higher in immunodeficient compared to immunocompetent patients. Higher prevalence rates are also seen in rural compared to urban communities. Most studies on prevalence have been carried out in developed countries where the laboratory and other health infrastructure are more accessible than those in developing countries. This relative inadequacy of laboratory diagnosis can affect accurate estimates of the prevalence of these infections in developing countries. However, reports of these infections in travellers and workers returning from developing countries can provide some indication of the extent of these problems. Most studies on prevalence of amoebiasis in developing countries were based on morphological identification of the parasite in faecal smears. As the pathogenic E. histolytica is morphologically indistinguishable from that of non-pathogenic E. dispar, estimates of amoebiasis may not be accurate. The epidemiology of human microsporidia infections is not completely understood. Two species, Enterocytozoon bieneusi and Encephalitozoon intestinalis, are associated with gastrointestinal disease in humans and it is believed that human to human as well as animal to human infections occur. However, the importance of zoonotic infections has not been fully characterised. G. duodenalis cysts, microsporidia and Cryptosporidium oocysts have been detected in various ground water resources, but their role in community outbreaks and maintenance of the infection has not been fully characterised. The taxonomic classification and pathogenic potential of B. hominis are still controversial. While considered by many as yeast, fungi or protozoon, recent sequence analysis of the complete SSUrRNA gene has placed it within an informal group, the stramenopiles. This review covers recent published data on these zoonotic infections and examines their public health importance in Asian countries.

Journal Article↗
PubMed1998

Comparison of richness and diversity of macroparasite communities among eels from Nova Scotia, the United Kingdom and Australia.

Species richness and diversity of macroparasite assemblages were compared among American eels (Anguilla rostrata) from Nova Scotia, European eels (A. anguilla) from the United Kingdom (Kennedy, Bush & Aho, 1986; Esch et al. 1988; Kennedy, 1990, 1993), and Australian eels (A. reinhardtii) from Queensland (Kennedy, 1995). Community richness and diversity of the macroparasite fauna of American and European eels did not differ significantly for total parasite component communities, intestinal parasite component communities, and intestinal parasite infracommunities. The similarities in richness and diversity between the parasite communities of American and European eels are not surprising given the common, recent origin of these sister species. However, differences in species composition were noted between Nova Scotia and the UK. Both species of eels were infected by a nearly identical suite of specialists, but differences occurred in the species number and composition of generalist parasites. In addition, generalist species were rarely dominant in Nova Scotia, but commonly so in the UK. These differences can be attributed to the differences in the freshwater fish fauna and their parasites that occur between Nova Scotia and the UK. American and European eels are derived from a common ancestor and, whereas they have carried with them a common suite of specialist parasites during their brief period of independence, they acquired different suites of generalists apparently from their respective continental faunas after they diverged. In contrast, parasite communities of American and European eels were significantly less diverse and speciose than those of Australian eels regardless of scale (total component community, intestinal component community, intestinal infracommunity). These results support the notion that parasite communities have had more time to evolve and/or that tropical conditions have promoted parasite speciation in Australian eels.

Anguilla↗
PubMed2000

Effect of parasite screening on refugee health.

Intestinal parasitic infections among refugees have been perceived as a public health problem for decades. A control program strategy to reduce morbidity and eventually transmission of intestinal parasites was initiated in 1993 by Mercy International (MI) for a group of Somalia refugee and has been implemented successfully. The management of the program operating within a comprehensive health care project and the control activities has been performed through the existing health facilities. This project was based on the "Comprehensive Health Care Approach" concept and applied to a collection of 10,000 Somali refugees. A project, which could be further, developed and modified for other similar situations. The strategy adopted was based on periodic chemotherapy of schoolchildren, intense health education in close collaboration with the local community leaders. An overall reduction in prevalence of intestinal parasitic infections of 53% was one of the targets achieved through this effort after three years of activities. 92% and 62% reduced the intensity of Ascaris lumbricoides and Trichuris trichiura infection, respectively. This approach in concert with the political commitment and limited operational costs is a warranty for the future sustainability of the control activities. Future control strategies are tailored to the results of evaluation surveys and are targeted to the identified high-risk areas. This project can be seen as a model in other refugee situation with the use of limited local resources.

Adult↗
PubMed2003

Treatment and prevention of intestinal parasite-associated disease.

Since 1917, only 11 new endoparasiticides have been developed for the horse, of which five chemical classes are in common use. The selection pressure of frequent administration of deworming doses for parasite control programs has been associated with the development of resistance of small strongyle parasites to the effects of benzimidazoles and pyrantel salts. Against the background of the inevitability of the occurrence of ivermectin/moxidectin resistance, responsible use of equine anthelmintics based on the clinical pharmacology of the compounds and the biology/epidemiology of intestinal parasites is a major issue for equine clinicians. The evidence base for the recommendations for treatment and control of equine intestinal parasites is sparse, however, and few robust data exist from controlled clinical trials to validate current guidelines.

Animals↗
PubMed1999

Parasitic infections of the intestines.

Intestinal parasites remain extremely common worldwide. In developing countries, intestinal protozoans are important causes of childhood diarrhea. Cryptosporidiosis is a common cause of chronic diarrhea in patients with AIDS. With the advent of current active antiretroviral therapy the incidence of cryptosporidiosis in AIDS has decreased. By contrast, Cryptosporidium, Cyclospora, and Giardia outbreaks continue to be associated with contamination of food or water. The intestinal helminths Ascaris, hookworm, and Trichuris each infects over a thousand million people. While most of those infected experience only minor symptoms, recent data highlight subtle effects of parasitism on cognitive function and nutrition. Efforts at disease control in developing countries are increasingly focused on mass chemotherapy.

Journal Article↗
PubMed1997

Parasites and Diarrhea. I: Protozoans and Diarrhea.

Intestinal parasitism is extremely common, with approximately 70% of all people harboring one or more intestinal parasite. Parasitism and diarrhea are both hyperendemic in areas where sanitation is suboptimal. Many clinicians assume that the identification of intestinal parasites in patients with diarrhea implies that the parasites are the cause. This approach is frequently misguided. Some intestinal parasites such as Giardia lamblia and Entamoeba histolytica certainly do cause diarrhea. Others, for example Entamoeba coli and Ascaris lumbricoides, almost certainly do not. In addition, there are a number of other organisms that have been associated with diarrheal illness in some cases, which may or may not be important pathogens. In this article, we will review the role of protozoans as definite and possible causes of diarrhea. In Part II, we review the role of helminths in diarrhea.

Journal Article↗
PubMedDate not supplied

Seroprevalence of Helicobacter pylori among children in Sana'a, Yemen.

BACKGROUND: Helicobacter pylori infection is primarily acquired in early childhood. Its transmission routes are debated. The aims of this study were to determine the seroprevalence of anti-H. pylori immunoglobulin G (IgG) in Yemeni children under 10 years of age, the potential risk factors for contracting H. pylori infection and co-infection of H. pylori with intestinal parasites. METHODS: Enzyme-labeled immunosorbent assay was used to determine the H. pylori prevalence rate among 572 healthy volunteers aged less than 10 years. Formalin ether concentration methods were used to test the prevalence of intestinal parasites (intestinal roundworms and tapeworms). In addition, we interviewed participants regarding potential risk factors for contracting H. pylori infection. RESULTS: The seroprevalence of H. pylori antibodies was 9%. The prevalence according to age varied from 0% in children under 2 years to 12.5% in age group 9-10 years. There was a correlation between the amounts of positive antibodies and increasing age. The prevalence rate of H. pylori antibodies was also significantly associated with the practice of drinking water from reused plastic jerry cans, with poor mouth hygiene and with co-infection by intestinal parasites. CONCLUSION: The prevalence of H. pylori antibodies in Yemen among children under 10 years of age is higher than that reported from other regions for the same age groups. Yemen shares some but not all potential risk factors for H. pylori infection with countries in which similar socioeconomic conditions are found. A possible way of eliminating H. pylori from the population would be via public health measures, i.e. preventing the reuse of plastic jerry cans, and improving sanitation and the standard of living.

Central Nervous System Parasitic Infections↗
PubMed1983

An examination of differences in serum antibody specificities and hypersensitivity reactions as contributing factors to chronic infection with the intestinal protozoan parasite, Giardia muris, in mice.

After oral administration of cysts of the intestinal protozoan parasite, Giardia muris, young male C3H/He mice are chronically infected, whereas BALB/c mice demonstrate a rapidly resolving pattern of infection. Both strains of mice injected with trophozoites in adjuvant and challenged orally with cysts develop serum antibodies to numerous trophozoite proteins. A limited number of these protein antigens was differentially immunoprecipitated by sera from resistant BALB/c and susceptible C3H/He mice exposed to G. muris. 35S-methionine-labelled protein antigens better recognized by immune BALB/c sera included molecules of relative mobility (Mr) 82,000 and a series of proteins of Mr 25,000 to 32,000. Differential recognition extended to a subset of solubilized trophozoite antigens that bind to the lectin, wheat germ agglutinin (WGA), and that can be radio-iodinated. In particular, a complex of 4 acidic protein antigens of approximate Mr 32,000, and designated collectively as Gm32, was better recognized by immune BALB/c serum than C3H/He serum. Isolated WGA-binding antigens were not able to consistently vaccinate BALB/c mice against subsequent G. muris infection. Moreover, preliminary evidence has been obtained that lack of antibody responsiveness to Gm32 does not segregate strictly with susceptibility to chronic infection in (BALB/c X C3H/He)F2 mice. These data, plus the observation that drug-cured C3H/He mice are highly resistant to reinfection, has led to examination of whether mice differ in the capacity of the intestines to support inflammatory responses. Mast cell deficient Wf/Wf mice, unlike wild-type litter-mates, developed chronic giardiasis although no reconstitution of resistance has yet been achieved with inocula of bone marrow cells from +/+ mice. BALB/c mice injected with the antihistamine and antiserotonin drug, cyproheptadine, also showed prolonged infections with G. muris. The data suggest that analysis of specificity differences in immune responses of mice varying in susceptibility to intestinal parasites must be supplemented by examination of the capacity of the intestine to support induced immune responses.

Animals↗
PubMed2005

The impact of host starvation on parasite development and population dynamics in an intestinal trypanosome parasite of bumble bees.

Host nutrition plays an important role in determining the development and success of parasitic infections. While studies of vertebrate hosts are accumulating, little is known about how host nutrition affects parasites of invertebrate hosts. Crithidia bombi is a gut trypanosome parasite of the bumble bee, Bombus terrestris and here we use it as a model system to determine the impact of host nutrition on the population dynamics and development of micro-parasites in invertebrates. Pollen-starved bees supported significantly smaller populations of the parasite. In pollen-fed bees the parasite showed a temporal pattern in development, with promastigote transmission stages appearing at the start of the infection and gradually being replaced by choanomastigote and amastigote forms. In pollen-starved bees this developmental process was disrupted, and there was no pattern in the appearance of these three forms. We discuss the implications of these results for parasite transmission, and speculate about the mechanisms behind these changes.

Animals↗
PubMed2004

Cryptosporidium parvum and other instestinal parasites among diarrhoeal patients referred to EHNRI in Ethiopia.

The occurrence of intestinal parasites in patients referred to the Parasitology Laboratory of the Ethiopian Health and Nutrition Research Institute (EHNRI), was recorded for four consecutive years, 1998-2001. Based on the stool appearance i.e. watery, loose, muciod and bloody, 442 diarrhoeal samples were particularly selected to allow diagnosis of intestinal parasites with emphasis on coccidian intestinal parasites. Wet saline mounts and formol ether concentration method with logul's iodine were performed for the detection of cysts, ova, trophozoites and larvae of intestinal parasites. Modified Ziehel Nelseen staining of stool smears was used to identify Cryptosporidum parvum and Isospora belli. The overall detection rate was 79.4% (351/442). The spectrum of positivity with any protozoa was 54.3% (240/442) and helminthes 25.1% (111/442). Cryptosporidium parvum was identified in 92/442 (20.8%). Isopora belli was identified among 35/442 (7.9%): Entamoeba histolytica/dispar scored second with positivity rate of 17.0% (75/442) and Giardia lamblia was found in 38/442 (8.6%) stool samples. As compared to protozoan parasites, detection rate with helminthes was very low. Among the helminthes. Strongyloides stercoralis was found in 38/442 (8.6%). This information strengthens the importance of intestinal protozoan parasites with recognition of the opportunistic parasites as major causes of diarrhoea. Their role in HIV/AIDS patients cannot be over-emphasized. Further awareness for the need of establishing different parasitological techniques at health service giving centers would enhance better understanding and management of diarrhoeal illness.

AIDS-Related Opportunistic Infections↗
PubMed1998

Intestinal nematode parasites, cytokines and effector mechanisms.

Laboratory models of intestinal nematode infection have played an important role in developing our understanding of the immune mechanisms that operate against infectious agents. The type of helper T cell response that develops following infection with intestinal nematode parasites is critical to the outcome of infection. The early events that mediate polarisation of the helper T cell subsets towards either Th1 or Th2 during intestinal nematode infection are not well characterised, but it is likely that multiple factors influence the induction of a Th1 or Th2 type response, just as multiple effector mechanisms are involved in worm expulsion. Costimulatory molecules have been shown to be important in driving T helper cell development down a specific pathway as has the immediate cytokine environment during T cell activation. If helper T cells of the Th2 type gain ascendancy then a protective immune response ensues, mediated by Th2 type cytokines and the effector mechanisms they control. In contrast, if an inappropriate Th1 type response predominates the ability to expel infection is compromised. Equally important is the observation that multiple potential effector mechanisms are stimulated by nematode infection, with a unique combination operating against the parasite depending on nematode species and its life cycle stage. Despite the close association between intestinal nematode infection and the generation of eosinophilia, mastocytosis and IgE it has been difficult to consistently demonstrate a role for these effector cells/molecules in resistance to nematode parasites, although mast cells are clearly important in some cases. It therefore seems that, in general, less classical Th2 controlled effector mechanisms, which remain poorly defined, are probably important in resistance to nematode parasites. Thus, our understanding of both the induction and effector phases remains incomplete and will remain an intense area of interest in the coming years.

Animals↗