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PubMed2005

Neuroparasitic infections: cestodes, trematodes, and protozoans.

Parasitic infection of the nervous system can produce a variety of symptoms and signs. Because symptoms of infection are often mild or nonspecific, diagnosis can be difficult. Familiarity with basic epidemiological characteristics and distinguishing radiographic findings can increase the likelihood of detection and proper treatment of parasitic infection of the nervous system. This article discusses the clinical presentation, diagnosis, and treatment for some of the more common infections of the nervous system caused by cestodes, trematodes and protozoans: Echinococcus spp., Spirometra spp. (sparganosis), Paragonimus spp., Schistosoma spp., Trypanosoma spp., Naegleria fowlerii, Acanthamoeba histolytica, and Balamuthia mandrillaris.

Animals↗
PubMed1978

Intestinal parasites of school children in urban and rural areas of Eastern Nigeria.

From October 1975 to March 1976 an epidemiological survey was carried out in Anambra and Imo states of Nigeria to determine the rate of intestinal worm and protozoan infections in school children. A total of 1742 children, out of which 813 from the urban and 929 from the rural school were screened of intestinal helminths and 1699 were also examined for intestinal protozoan infections. Concentration methods HCL-Ether centrifugation technique and Heidenhain's iron-hematoxylin staining method respectively were adopted for the identification of helminth eggs and protozoal cysts. 1405, i.e. 81% of the total number examined, eggs of one or more helminth species were detected. Carriage-rates of helminth infections were highest (87%) in children from the rural schools, in whom hookworm (90% of carriers) predominated. Besides high rates of hookworm, ascaris and trichuris infections, other parasites of public health importance (Schistosoma mansoni, Paragonimus uterobilateralis and Diphylobothrium latum) were detected. Significantly an increase in the rate of helminthic infections with age was noted in the survey. 55% of the 1699 children examined were carriers of cysts of one or more protozoa species. Higher carriage-rate (56%) of protozoan infections was noted in urban children. Comparatively lambliasis predominated in the urban children, while infection with E. histolytica was recorded slightly higher in rural children.

Adolescent↗
PubMed2000

Cyclospora infection in acquired immunodeficiency syndrome.

BACKGROUND: Diarrhea is a common clinical manifestation of human immunodeficiency virus (HIV) infection. The important protozoan pathogens causing diarrhea include cryptosporidium, microsporidium, Isospora belli and cyclospora besides giardia lamblia and entamoeba histolytica. OBJECTIVE: The objective of the present study was to determine the incidence of cyclospora (a coccidian protozoan) infection in HIV infected patients. METHODOLOGY: Faecal smears were stained by modified acid fast staining method to demonstrate oocysts of cyclospora. RESULTS: Out of 334 faecal specimens which were studied, cyclospora were identified in 22 cases (6.6 percent); and in 50 percent of the patients, there was a mixed infection with another protozoan parasite namely cryptosporidium. CONCLUSION: Identification of this parasite is important because cyclosporiasis can be treated with trimethoprim-sulfamethoxazole. Outbreaks of cyclospora infection have been linked to waterborne transmission. Though adequately chlorinated water is free of coliforms, it can still contain cyclospora.

AIDS-Related Opportunistic Infections↗
PubMed1992

Evaluating measures to control intestinal parasitic infections.

Intestinal parasitic infections are among the most common infections of humans in developing countries, but the resources available for their control are severely limited. Careful evaluation of control measures is essential to ensure that they are cost-effective. The evaluation of the effects of control on intestinal helminths and intestinal protozoa requires an understanding of the different epidemiological patterns of these two groups of parasites. The transmission dynamics and morbidity associated with the major helminth infections (Ascaris lumbricoides, Trichuris trichiura and the hookworms) are dependent on the size of the worm burdens. Thus the important parameter for evaluating the impact of control on morbidity and transmission is the intensity of infection, which can be assessed by determining the mean density of parasite eggs in faecal specimens. Estimation of intensity is subject to systematic errors, however, due to the complex pattern of worm burden distributions. The frequency distribution of burdens is highly overdispersed, and individuals exhibit predisposition to particular levels of infection. Furthermore, mean intensity is age-dependent, in a species-specific manner, and is clustered spatially and within families. These complex patterns imply that the estimation of intensity is exceptionally sensitive to the size and demographic structure of the population sample selected for assessment. They also have the effect that prevalence estimates, the most commonly used measures of infection in communities, can seriously mislead. Paradoxically, prevalence is least useful where infection is most common because the relationship between prevalence and intensity is most markedly non-linear when the prevalence is high. Thus in areas where control is most needed, evaluation using prevalence might suggest that control had failed while evaluation by intensity would, correctly, show the measure of success. With the major protozoan infections (Entamoeba histolytica, Giardia duodenalis and Cryptosporidium parvum) an estimate of intensity is of little value and the central parameter for evaluation is prevalence. Prevalence does exhibit age and spatial heterogeneity, which may be species-specific, so there remains a need to ensure a consistent sample structure, although this is less critical than for the helminths. The major constraint on evaluating the control of protozoan infections is the need to identify pathogenic species and, in some cases, pathogenic strains. Harmless commensal protozoans are ubiquitous and often morphologically very similar to pathogens, but their control is both unnecessary and impracticable. Species such a E. histolytica appear to exist as strains with differing pathogenicity, thus control will be cost-effective only if the focus is on pathogenic strains. Effective diagnosis is therefore central to the evaluation of the control of protozoan infections.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed2001

Microbes and microbial toxins: paradigms for microbial-mucosal interactions I. Pathophysiological aspects of enteric infections with the lumen-dwelling protozoan pathogen Giardia lamblia.

Giardia lamblia is one of the most important causes of waterborne diarrheal disease worldwide, and giardiasis is the most common protozoan infection of the human small intestine. Symptomatic infection is characterized by diarrhea, abdominal pain, and malabsorption, leading to malnutrition and weight loss, particularly in children. The pathogen resides strictly in the lumen of the small intestine, and infection is typically not accompanied by significant mucosal inflammation. Clinical and experimental studies indicate that B cell-dependent host defenses, particularly IgA, are important for controlling and clearing Giardia infection, although B cell-independent mechanisms also contribute to this outcome. In contrast to antigiardial host defenses, much less is known about the pathophysiological mechanisms underlying the clinical symptoms of giardiasis, partly because of the current lack of suitable model systems. In addition to being an important human enteric pathogen, Giardia is an interesting model organism for gaining basic insights into genetic innovations that led to evolution of eukaryotic cells, since it belongs to the earliest diverging eukaryotic lineage known. The completion of the giardial genome project will increase understanding of the basic biology of the protozoan and will help us to better understand host pathogen-interactions as a basis for developing new vaccination and therapeutic strategies.

Animals↗
PubMed1983

Evaluation of two serological tests for Trichomonas vaginalis infection.

Trichomonas vaginalis is a widely prevalent, sexually transmitted protozoan infecting both males and females. Despite its prevalence, little is known about its contribution to the morbidity rates for urogenital-tract infections. Currently accepted diagnostic methods are limited to the demonstration of the organism in fresh material, identification in stained material, or in vitro cultivation of organisms from the urogenital tract. We have evaluated the indirect hemagglutination test and the gel diffusion test for efficacy in detecting antibodies in serum samples drawn from two population groups. Sera from patients attending a vaginitis clinic had a seropositivity rate of 69% by indirect hemagglutination and 34% by gel diffusion. Seropositivity rates among culture-positive patients were 78% with indirect hemagglutination and 43% with gel diffusion. A group of normal female hospital employees showed seropositivity rates of 30% by indirect hemagglutination and 3% by gel diffusion. Absorption of reactive sera with Trichomonas antigens reduced or abolished the serological reactivity, confirming the specificity of the test. Serological methods can provide a rapid, sensitive, and economical tool to study the epidemiology of this common protozoan infection.

Antigens↗
PubMed1994

New parasites on the block: emerging intestinal protozoa.

Several trends in clinical medicine have converged recently and placed intestinal protozoan infections in a position of increasing importance to health professionals. These trends include the pandemic of human immunodeficiency virus (HIV) infections that cause the acquired immunodeficiency syndrome (AIDS) and result in associated opportunistic infections. The increasing use of powerful chemotherapeutic and immunosuppressive agents to prevent rejection of transplanted tissues in human allograft recipients has predisposed these patients to intestinal parasitic infections, which often become chronic and debilitating. Large numbers of people engage in business, philanthropic work, and vacation travel on a worldwide basis. The number of susceptible, potential human hosts for parasitic infections will continue to increase in the coming years. We reviewed 4 protozoan infections that have recently attracted the interest of clinicians, either because they are newly discovered or because they are increasingly prevalent. These infections include cryptosporidiosis and recently described infections due to Cyclospora species. The AIDS pandemic has also been associated with both the discovery and the rapid emergence of human microsporidiosis. Isospora belli has received renewed attention because of chronic infections now observed in HIV-infected hosts.

AIDS-Related Opportunistic Infections↗
PubMed2002

Health effect of human wastes use in agriculture in El Azzouzia (the wastewater spreading area of Marrakesh city, Morocco).

The use of wastewater and excreta in agriculture constitutes an important source of spread Salmonella strains and protozoan infections into the environment. This practice has been used in El Azzouzia (the wastewater-spreading area of Marrakesh city, Morocco) for several years. The available circumstantial evidence gained from epidemiological and microbiological investigations suggests that the use of untreated wastewater causes an excess of protozoan infections among children living in El Azzouzia (72%) compared with those from a control area (45%). The pathogenic protozoan infections observed were giardiasis (39%) and amoebiasis (28%). For Salmonella infection, 21.34% of the exposed children were infected, while this rate did not exceed 1.14% in the control group. The serogroups B and C were the most commonly isolated. The sewage farming children are therefore more exposed to detectable risk from pathogenic micro-organisms than the control children.

Adolescent↗
PubMedDate not supplied

[Laboratory diagnosis of intestinal protozoan opportunistic infections in Goiânia, GO].

Cryptosporidiosis, isosporiasis, cyclosporiasis and microsporídiosis have become common in immunocompromised patients. The diagnosis of these diseases is important, because although they produce similar clinical pictures, they have a different therapeutic approach and prognostic. Seeking to evaluate the situation of the diagnosis of these parasites, the laboratories of the SUS network and health centers of the district of Goiânia-GO were mapped.

Brazil↗
PubMedDate not supplied

[Helminth and protozoan intestinal infections in pregnant women in their first consultation at Health Centers of the State in the Butantã Subdistrict, São Paulo City].

481 pregnant women attended at first consultation from a São Paulo city suburb-subdistrict of Butantan-São Paulo State, Brazil, from April to October of 1988, were investigated regarding the prevalence of verminosis. The mean age was 24.5 years (range 14-46), the average family income was 0.97 PCMW (per capita minimum wage) and the average number of members of the family was 4 (1 to 15). The verminosis prevalence was 45.1% among the women. The most frequent parasites were: Ascaris lumbricoides (19.0%), ancilostomídeos (16.7%) and Trichuris trichiura (15.9%). The verminosis prevalence was significantly higher among the pregnant women (p < 0.05) who belonged to the families with income below 0.5 PCMW and greater than 4 members.

Adolescent↗
PubMed2005

[Opportunistic protozoa--the problem in immunodeficient patients].

Protozoan infections with a mild or asymptomatic course in immunocompetent individuals, in the case of immunocompromised patients could cause severe syndromes or fatal outcome. The different clinical course is possible to diagnose only with specific laboratory methods. Actual settlements on the most often diagnosed in human opportunistic protozoan infections pathogenesis and diagnostics are presented.

Animals↗
PubMedDate not supplied

Parasitic infections in asymptomatic homosexual men: cost-effective screening.

The purpose of this study was to develop a cost-effective strategy for screening for enteric protozoan infections in homosexual men without gastrointestinal symptoms suggesting infection. One hundred and one homosexual men in Portland, Oregon, each submitted at least one unpurged stool sample; 91% submitted three samples each. Of these, 27% had Entamoeba histolytica, 61% had nonpathogenic protozoa with or without E. histolytica, 36% had a nonpathogen alone, and 3% had Giardia lamblia. Protozoan infection was highly associated with the practice of anilingus (p less than 0.005). Infection with E. histolytica correlated significantly with the presence of nonpathogenic protozoa (p less than 0.005). The following screening strategy was judged to be the most cost-effective: examine one sample first; if E. histolytica is found or if the sample is negative, no further investigation is required; if a nonpathogen is found, one additional sample should be obtained. This strategy had a sensitivity for E. histolytica of 85% and a cost of $136 per case detected.

Adult↗
PubMed2005

Behavioral and hygienic characteristics of primary schoolchildren which can be modified to reduce the prevalence of geohelminth infections: a study in central Java, Indonesia.

Five schools in central Java that enroll more than 500 students in grades one through six were chosen for a study of the prevalence of parasitic geohelminths and selected protozoan infections. The schools are located in regions that differ in geological features, density of vegetation and cultural and economic attributes. The prevalence of soil-transmitted helminths among children in the five schools ranged from 8.7% to 76.1%, and protozoan infections from 2.8% to 32.1%. The principal objective of the study was to identify physical, hygienic and behavioral characteristics of the children that increase the likelihood of becoming infected. Although most of the characteristics studied are considered to be contributing factors, few previous attempts have been made to rank them in order of importance in causing infection. The results of this study suggest that a systematic and sustained effort to teach children to (a) avoid certain types of behavior that favor infection, and (b) practice good personal hygiene, are the best approaches to significant and enduring reduction of the scourge of intestinal parasitism.

Animals↗
PubMed2001

Activation of Toll-like receptor-2 by glycosylphosphatidylinositol anchors from a protozoan parasite.

Glycosylphosphatidylinositol (GPI) anchors and glycoinositolphospholipids (GIPLs) from parasitic protozoa have been shown to exert a wide variety of effects on cells of the host innate immune system. However, the receptor(s) that are triggered by these protozoan glycolipids has not been identified. Here we present evidence that Trypanosoma cruzi-derived GPI anchors and GIPLs trigger CD25 expression on Chinese hamster ovary-K1 cells transfected with CD14 and Toll-like receptor-2 (TLR-2), but not wild-type (TLR-2-deficient) Chinese hamster ovary cells. The protozoan-derived GPI anchors and GIPLs containing alkylacylglycerol and saturated fatty acid chains or ceramide were found to be active in a concentration range of 100 nM to 1 microM. More importantly, the GPI anchors purified from T. cruzi trypomastigotes, which contain a longer glycan core and unsaturated fatty acids in the sn-2 position of the alkylacylglycerolipid component, triggered TLR-2 at subnanomolar concentrations. We performed experiments with macrophages from TLR-2 knockout and TLR-4 knockout mice, and found that TLR-2 expression appears to be essential for induction of IL-12, TNF-alpha, and NO by GPI anchors derived from T. cruzi trypomastigotes. Thus, highly purified GPI anchors from T. cruzi parasites are potent activators of TLR-2 from both mouse and human origin. The activation of TLR-2 may initiate host innate defense mechanisms and inflammatory response during protozoan infection, and may provide new strategies for immune intervention during protozoan infections.

Animals↗
PubMed1985

[Antiparasitic therapy of children in Equatorial Africa].

Parasitic infections are endemic in children in Africa, making eradication an impossibility. Therapy is directed towards the individual manifesting an imbalance in the host-parasite relationship. Sanitation education is often disappointing, and until effective vaccines are developed, drug therapy remains the only worthwhile intervention. In order for a drug to be used on a mass campaign basis, financial considerations and side effects are of primary importance. Mefloquine has been shown to be a useful second line drug for chloroquine resistant strains of malaria in our Parasitology department. Benzimidazoles in a single dose are useful for intestinal nematode infections. New drugs are now available for schistosomiasis, filariasis, and protozoan infections.

Child↗
PubMed1986

The immune response during proliferative kidney disease in rainbow trout: a case history.

Young-of-the-year rainbow trout clinically affected by proliferative kidney disease (PKD), a systemic protozoan infection, exhibit a massive proliferation of small lymphocytes in the posterior kidney and spleen, a decrease in erythrocyte packed cell volume, hemoglobin, and serum albumins and an increase in beta-globulins. Electronphotomicrographs of the causative agent indicate that it is engulfed within a macrophage which is surrounded by small lymphocytes. Fish having survived a clinical episode are completely refractory to subsequent infection. Their serum electrophoretic patterns are quite unremarkable.

Animals↗
PubMed1991

Leucocytozoon-like infection in parakeets, budgerigars and a common buzzard.

The gross and histological lesions of a protozoan infection, possibly caused by Leucocytozoon, in parakeets (genera Neophema and Cyanoramphus), budgerigars (Melopsittacus undulatus) and a wild buzzard (Buteo buteo) are described. The infection appears not to have been identified before in budgerigars in Great Britain, and in its chronic form resulted in vomiting and wasting. The possible identity of the parasite and the epidemiological factors are considered.

Animals↗