Prevalence of intestinal parasitic infections in patients with acquired immunodeficiency syndrome in Brazil

Association between Blastocystis sp. infection and immunocompromised patients: a systematic review and meta-analysis

The significance of opportunistic infections in immunocompromised patients and the enigmatic pathogenicity of Blastocystis directed us to conduct the first global systematic review and meta-analysis on Blastocystis prevalence, odds ratios (ORs), and subtypes distribution in various immunocompromised patients (HIV/AIDS, cancer and hemodialysis patients, as well as transplant recipients). The systematic searching procedure was done in Web of Science, PubMed, Scopus, and Google Scholar databases for relevant published literature until November 11, 2020. Random-effects model was utilized to calculate the weighted estimates and 95% confidence intervals (95% CIs). The computed pooled prevalence of Blastocystis inferred from 118 papers (128 datasets) on immunocompromised patients was 10.3% (95% CI: 8.7-12.2%), with 16.1% (95% CI: 11.3-22.2%), 12.5% (95% CI: 8.5-18%), 8.4% (95 % CI: 6.6-10.6%), and 6% (95% CI: 2.6-13.3%) for hemodialysis patients, cancer patients, HIV/AIDS patients, and transplant recipients, respectively. Based on 50 case-control studies (54 datasets), the highest ORs were associated with cancer [2.81 (95% CI: 1.24-6.38, P = 0.013)] and hemodialysis patients [2.78 (95% CI: 1.19-6.48, P = 0.018)]. The most frequent subtype being found in immunocompromised patients was ST3 [41.7% (95% CI: 31.4-52.7%)], followed by ST1 [31.7% (95% CI: 23.2-41.8%)] and ST2 [23.1% (95% CI: 14.8-34.1%)]. Also, the weighted frequency of Blastocystis in various subgroups (publication year, WHO regions, geographical distribution, continents, and country income) was analyzed separately. In total, the results of the present meta-analysis highlighted that one's immunodeficiency status is probably associated with an increased Blastocystis infection, underpinning strict preventive measures to be taken.

Diversity, geographical distribution, and prevalence of Entamoeba spp. in Brazil: a systematic review and meta-analysis

The genus Entamoeba includes a variety of widely distributed species adapted to live in the digestive tracts of humans and a large variety of animals of different classes. The objective of this study was to investigate the prevalence, distribution, and molecular epidemiology of Entamoeba spp. in different classes of hosts in Brazil. Studies that analyzed hosts from several classes, including humans and domestic, wild, or captive animals, were considered. The pooled prevalence of Entamoeba spp. was calculated using the random-effects model. A total of 166 studies on humans and 16 on animals were included. The prevalence of Entamoeba spp. in the Brazilian population was 22% (95% CI: 21–24). The state with the highest prevalence was Paraiba with 72%, followed by Federal District with 53%, and Rondonia with 50%. In immunocompromized patients, the prevalence was 18%, and cancer (36%) was the most prevalent cause of immunosuppression. The prevalence of Entamoeba spp. in animal hosts was 12% (95% CI: 7–17). Captive wild animals and domestic farm animals showed the highest prevalence, with 16% and 15%, respectively. The species found more often were E. coli (86.5%), E. dispar (7.9%), and E. histolytica (3.1%). In conclusion, a high prevalence (22%) of Entamoeba spp. was found in the Brazilian population, with a prevalence of up to 50% mainly in the northern, northeastern, and central-western regions. The pathogenic species E. histolytica is distributed in most Brazilian regions, with significant prevalence percentages. Among animals, unidentified Entamoeba species were most prevalent in mammals.

Intestinal parasitic infections and associated factors among people living with HIV/AIDS in Ethiopia: A systematic review and meta-analysis

Background

Intestinal parasitic infections are major public health problems throughout the world, particularly in people living with HIV/AIDS. People living with HIV/AIDS are vulnerable groups for a variety of diseases, hence they are easily affected by opportunistic and non-opportunistic intestinal parasites due to the weakening of their immunity. Therefore, this study aimed to estimate the pooled prevalence and factors associated with intestinal parasitic infections among people living with HIV/AIDS in Ethiopia.

Methods

Articles were identified through search engines in the online electronic databases PubMed/MEDLINE, EMBASE, HINARI, CINAHL, Cochrane Library, Google Scholar, and reference lists of previous studies following the PRISMA Protocol. Studies conducted between 2003 and 2020 with English language were included in this study. This review included papers with having high-quality NOS scores. Meta-analysis was computed using STATA version 11 software. Heterogeneity was assessed using the Cochrane Q-test and I² test statistics. Subgroup and sensitivity analysis was employed with evidence of heterogeneity. Publication bias was determined using the funnel plot and Egger’s regression test statistic.

Results

This study included a total of twenty-two cross-sectional studies with 5,833 study participants. The mean age of the study participants was 35 years old. The pooled prevalence of intestinal parasitic infection among people living with HIV/AIDS in Ethiopia was 39.15% (95%CI: 32.34, 45.95). The pooled prevalence of intestinal parasitic infections among people living with HIV/AIDS who had taking ART and who had not to start ART was found to be 28.27% (95%CI 22.47, 34.06) and 41.63% (95%CI: 28.75, 54.52) respectively. Unavailability of latrine (AOR: 4.87, (95% CI: 2.39, 9.92)), CD4+ T cell count <200cells/μl ((AOR: 3.53, (95%CI: 1.98, 6.27)), and having a history of diarrhea (AOR: 4.79 (95%CI: 1.53, 14.99) were factors significantly associated with intestinal parasitic infections.

Conclusion

In this study, the overall pooled prevalence of intestinal parasitic infections among HIV/AIDS patients in Ethiopia was relatively high. CD4+ T-cell count <200cells/μl, unavailability of a latrine, and history of diarrhea were significantly associated with intestinal parasitic infections. Therefore, the policymakers and health care professionals could give special attention to the presence of latrines, early detection and treatment of intestinal parasitic infections, and early initiation of ART drugs.

Worldwide prevalence of emerging parasite Blastocystis in immunocompromised patients: A systematic review and meta-analysis

BACKGROUND

Blastocystis is one of the most common pathogens of the human intestine, caused by an emerging parasite, which can lead to severe symptoms and even death in immunocompromised patients. We aimed to determine the global prevalence of Blastocystosis infection in people with immunodeficiency. A systematic literature search was conducted on Web of Science, Scopus, Google scholar, Science Direct and MEDLINE databases to select all observational studies reporting the prevalence of Blastocystosis infection in Worldwide, based on different diagnostic methods in immunocompromised patients of any age and published from inception to February 2019. Pooled estimates and 95% confidence intervals (95% CIs) were calculated using random effects models and in addition, the I² statistic was calculated. The geographic distribution of studies was evaluated and the diagnosis of Blastocystis was compared by various techniques. Electronic databases were reviewed for Blastocystosis infection in HIV/AIDS, cancer and other immunocompromised patients, and meta-analyses were conducted to calculate the overall estimated prevalence. Total68 eligible studies were included. The estimated pooled prevalence rate of Blastocystosis infection in immunocompromised patients was overall 10% (95% CI, 7-13%; I² 96.04%) (P < 0.001), of whom 21% [18-25] were in Australia, 12% [4-24] in America, 11% [6-17] in Europe and 10% [5-15], 7% [3-13] in Asia and Africa, respectively. It was calculated that the estimated pooled prevalence rate of Blastocystosis infection in immunocompromised patients was overall 10% and the prevalence estimates ranged from 0.44 to 72.39. Also, overall the prevalence of parasites co-infection in immunocompromised patients was detected as 0.024%. Our finding showed that immunocompromised people show a high prevalence of Blastocystosis infection compared to the control population. Adequate information on the prevalence rate is still missing from many countries. However, current information underscore that Blastocystis should not be neglected.

Prevalence of Blastocystis sp. infection in several hosts in Brazil: a systematic review and meta-analysis

BACKGROUND

Blastocystis sp. affects a wide variety of animals and is the most common protozoan in human fecal samples with potential pandemic distribution. In the present study, a systematic review and meta-analysis were conducted to determine the prevalence and distribution of Blastocystis sp. in different classes of hosts in Brazil.

METHODS

Studies that analyzed hosts of various classes, including humans, domestic animals, wild animals or captive animals, were considered. The pooled prevalence of Blastocystis sp. infection was estimated by random effects models.

RESULTS

For humans, similar prevalence rates were found for males (31.0%, 95% CI: 17.0-45.0%; weight 10%) and females (28.0%, 95% CI: 16.0-41.0%; weight 10%); the state of Mato Grosso do Sul showed the highest prevalence, with 41.0% positivity (95% CI: 36.0-46.0%; weight 2.9%). The prevalence among immunocompromised patients was 5.0% (95% CI: 3.0-7.0%; weight 10%), and the most common cause of immunosuppression was hemodialysis, with 23.0% (95% CI: 17.0-29.0%; weight 12.4%). Among classifications according to interaction with humans, wild and domestic animals presented values of 19.0% (95% CI: 7.0-31.0%; weight 42.6%) and 17.0% (95% CI: 13.0-21.0%; weight 29.6%), respectively. Among these animals, mammals (39.0%, 95% CI: 21.0-56.0%; weight 47.3%) and birds (18.0%, 95% CI: 10.0-27.0%; weight 39.3%) exhibited the highest prevalence. Phylogenetic analysis of Blastocystis sp. revealed greater genetic diversity for clades of subtypes (STs) ST1, ST2 and ST3.

CONCLUSIONS

The overall prevalence of Blastocystis sp. in the Brazilian human population was 24%, which reflects the reality in the South, Southeast and Midwest regions, where prevalence rates of up to 40% were found. Among animals, mammals and birds exhibited the highest prevalence.

Cystoisospora belli infections in humans: the past 100 years

Cystoisospora belli is a coccidian parasite of humans, with a direct fecal-oral transmission cycle. It is globally distributed, but mainly found in tropical and subtropical areas. Many cases of C. belli infections have been reported in patients with HIV, and in patients undergoing immunosuppressive therapy for organ transplants or those treated for tumours worldwide. Unsporulated or partially sporulated oocysts of C. belli are excreted in feces. When sporulated oocysts in contaminated water or food are ingested, asexual and sexual stages of C. belli are confined to the epithelium of intestines, bile ducts and gallbladder. Monozoic tissue cysts are present in extra-intestinal organs (lamina propria of the small and large intestine, lymph nodes, spleen, and liver) of immunosuppressed humans. However, a paratenic host has not been demonstrated. Cystoisospora belli infections can be persistent, lasting for months, and relapses are common; the mechanism of relapse is unknown. Recently, the endogenous stages of C. belli were re-examined and attention was drawn to cases of misidentification of non-protozoal structures in the gallbladder of patients as C. belli. Here, we review all aspects of the biology of C. belli, including morphology, endogenous stages, prevalence, epidemiology, symptoms, diagnosis and control.

Pragmatic Combination of Available Diagnostic Tools for Optimal Detection of Intestinal Microsporidia

Diarrhea is a debilitating condition in HIV infected individuals and with the finding that almost 1/4 cases of diarrhea in HIV are due to microsporidia, there is a dire need to institute measures for its detection on a regular basis. Keeping this in mind the study aims to determine the burden of intestinal microsporidiosis in HIV seropositive patients presenting with and without diarrhea and to compare the ability of microscopy and PCR in its detection.The study group consisted of 120 patients divided into four groups HIV seropositive with/without diarrhea, and HIV seronegative with/without diarrhea. Performance of four staining techniques including Modified Trichrome, Calcofluor White, Gram Chromotrope and Quick hot Gram Chromotrope stains were evaluated against PCR in diagnosing enteric microsporidiosis from stool samples.Overall prevalence of intestinal microsporidiosis was 10.83%. The same for HIV seropositive patients with diarrhea was 23.33%, HIV seropositive patients without diarrhea and in immune-competent hosts with diarrhea was 10% each. Enterocytozoon bieneusi was found to predominate. Calcofluor white stain detected maximum microsporidia in stool samples (76.92%), followed by Modified Trichrome stain (61.5%), PCR (46.15%) and Gram Chromotrope and Quick hot Gram Chromotrope stains (38.4% each). PCR exhibited the best performance with a sensitivity and specificity of 100%. Our data suggests screening of stool samples with either Modified Trichrome or Calcofluor white stain followed by PCR confirmation thus leading to maximum detection along with speciation for complete cure.

A Study of Parasitic and Bacterial Pathogens Associated with Diarrhea in HIV-Positive Patients

INTRODUCTION

Diarrhea is a common complication of acquired immune deficiency syndrome (AIDS), occurring in almost 90% of AIDS patients in developing countries like India. The present study was aimed to determine the prevalence and microbiological profile of pathogens associated with diarrhea in human immunodeficiency virus (HIV) positive patients and their relation to CD4 counts.

MATERIALS AND METHODS

Forty-five successive HIV-positive patients, 27 with diarrhea (study group) and 18 without diarrhea (control group), were included in the three-month study. The HIV infection was confirmed by three different antibody detection tests. The stool samples were collected on two consecutive days and were examined for parasites by microscopy using wet mount and modified Ziehl-Neelsen stain. They were examined for bacteria by Gram stain and conventional Ziehl-Neelsen stain and were inoculated on appropriate culture media. The isolates were identified by standard biochemical tests, followed by antibiotic susceptibility testing using the Kirby-Bauer disc diffusion method.

RESULTS 

Twenty-four pathogens were detected in diarrheal HIV-positive patients, including 14 parasites (58.33%), seven bacteria (29.17%), and three fungi (12.50%). Isospora sp. was the most common parasite (25.9%) followed by Cryptosporidium sp. (14.8%). Other parasites included Cyclospora sp., Strongyloides stercoralis, and Entamoeba histolytica (3.7% each).​ Escherichia coli (18.5%) was the most common bacterial isolate, of which, 80% were Enterotoxigenic E. coli (ETEC) while 20% were Enteropathogenic E. coli (EPEC). Other isolates included Shigella flexneri and Mycobacterium tuberculosis (3.7% each). The isolates were sensitive to furazolidone (94.11%), chloramphenicol (76.47%), and gentamicin (52.94%). The isolates from diarrheal patients showed resistance to norfloxacin (5.88% vs. 50%, p<0.05) as compared to those from non-diarrheal patients. The diarrheal HIV-positive patients had lower mean CD4 counts (202.6 cells/µL), as compared to those without diarrhea (239.28 cells/µL).

CONCLUSION 

Isospora sp. is the most common parasite and Escherichia​ coli is the most common bacterium associated with diarrhea in HIV patients. The antibiotic sensitivity patterns should be monitored regularly to detect resistance to commonly used drugs. The prevalence of organisms in a region, various clinical manifestations, sensitivity patterns of isolates, and relation with CD4 count should be considered while instituting therapy in HIV patients with diarrhea.

OCCURRENCE OF Blastocystis spp. IN UBERABA, MINAS GERAIS, BRAZIL

Intestinal parasites are a problem for public health all over the world. The infection with Blastocystis, a protozoan of controversial pathogenicity, is one of the most common among them all. In this study, the occurrence of intestinal parasites, with emphasis on Blastocystis, in patients at the Universidade Federal do Triângulo Mineiro was investigated in Uberaba (MG) through microscopy of direct smears and fecal concentrates using Ritchie’s method. Feces of 1,323 patients were examined from April 2011 to May 2012. In 28.7% of them at least one intestinal parasite was identified, and the most frequent organisms were Blastocystis spp. (17.8%) and Giardia intestinalis (7.4%). The occurrence of parasitism was higher in children aged 6 -10 years old, and the infection with Blastocystis spp. was higher above the age of six (p < 0.001). The exclusive presence of G. intestinalis and of Blastocystis spp. was observed in 5.4% and 12.2% of the patients, respectively. Regarding patients with diarrheic feces, 8% revealed unique parasitism of Blastocystis spp. Other intestinal parasites observed in children were Ascaris lumbricoides(0.3%) and Entamoeba histolytica/dispar/moshkovskii (1.4%). The Ritchie’s method was more sensitive (92.8%) when compared to direct microscopy (89.8%), with high agreement between them (97.7%, kappa = 0.92). In conclusion, the occurrence of Blastocystis spp. in Uberaba is high and the presence of diarrheic feces with exclusive presence of the parasite of Blastocystis spp. was observed.

Pattern of co-infection by enteric pathogenic parasites among HIV sero-positive individuals in a Tertiary Care Hospital, Mumbai, India

INTRODUCTION

One of the major medical concerns in people living with HIV/AIDS (PLHA) is management of diarrhea that can lead to severe morbidity and mortality. Such clinical scenario warrants an analysis of intestinal parasites, which are important opportunistic pathogens in PLHA. Owing to the scarcity of recent pattern of intestinal opportunistic infections from this region, the study was designed to determine the opportunistic parasites causing diarrhea in PLHA; and to find out whether there is any significant difference in the enteric parasitic pathogens in patients with different immunological status and in those on highly active anti retro-viral therapy (HAART).

MATERIALS AND METHODS

Analysis of the spectrum of intestinal parasites was carried out with 192 subjects in two groups (142 HIV sero-positive patients having diarrhea and 50 HIV sero-negative patients having diarrhea). The routine light microscopic examination was carried out to determine the infection and CD4+ T-Lymphocyte count was estimated using flow cytometry.

RESULTS

Enteric parasites were detected in 35.9% of HIV sero-positive patients having diarrhea and 18% of HIV sero-negative patients having diarrhea. Most common opportunistic enteric parasite was Isospora belli (11.5%); others were Entamoeba histolytica (4.7%), Cryptosporidium sp. (3.6%), Strongyloides stercoralis (3.1%), Giardia intestinalis (3.1%) and Cyclospora cayatanenesis (1.6%). Opportunistic enteric parasites were detected in significantly low numbers in patients with CD4+ T-Lymphocyte counts >500 cells/ml; and in those taking HAART.

Prevalence of strongyloidiasis in Latin America: a systematic review of the literature

Strongyloides stercoralis is rarely recognized as a major public health issue, probably because its burden is largely underestimated. We reviewed the literature (both PubMed and 'grey' literature) about the prevalence of strongyloidiasis in Latin America, an area of presumable high endemicity. There were finally 88 papers involved in the analysis, covering the period between 1981 and 2011. Studies were heterogeneous in several aspects, such as the populations screened and the diagnostic methods used. Most of the studies relied on direct coproparasitological examination, which has low sensitivity for the detection of S. stercoralis larvae. The following countries presented areas of high prevalence (>20%): Argentina, Ecuador, Venezuela, Peru and Brazil. Globally, for most of the included countries it was not possible to define reliable data because of paucity and/or inadequacy of studies. S. stercoralis requires specific diagnostic methods for its detection; therefore, surveys should be specifically designed in order to avoid underestimation of the infection.

Strongyloidiasis--an insight into its global prevalence and management

BACKGROUND

Strongyloides stercoralis, an intestinal parasitic nematode, infects more than 100 million people worldwide. Strongyloides are unique in their ability to exist as a free-living and autoinfective cycle. Strongyloidiasis can occur without any symptoms or as a potentially fatal hyperinfection or disseminated infection. The most common risk factors for these complications are immunosuppression caused by corticosteroids and infection with human T-lymphotropic virus or human immunodeficiency virus. Even though the diagnosis of strongyloidiasis is improved by advanced instrumentation techniques in isolated and complicated cases of hyperinfection or dissemination, efficient guidelines for screening the population in epidemiological surveys are lacking.

METHODOLOGY AND RESULTS

In this review, we have discussed various conventional methods for the diagnosis and management of this disease, with an emphasis on recently developed molecular and serological methods that could be implemented to establish guidelines for precise diagnosis of infection in patients and screening in epidemiological surveys. A comprehensive analysis of various cases reported worldwide from different endemic and nonendemic foci of the disease for the last 40 years was evaluated in an effort to delineate the global prevalence of this disease. We also updated the current knowledge of the various clinical spectrum of this parasitic disease, with an emphasis on newer molecular diagnostic methods, treatment, and management of cases in immunosuppressed patients.

CONCLUSION

Strongyloidiasis is considered a neglected tropical disease and is probably an underdiagnosed parasitic disease due to its low parasitic load and uncertain clinical symptoms. Increased infectivity rates in many developed countries and nonendemic regions nearing those in the most prevalent endemic regions of this parasite and the increasing transmission potential to immigrants, travelers, and immunosuppressed populations are indications for initiating an integrated approach towards prompt diagnosis and control of this parasitic disease.

Management of chronic Giardia infection

Advances in our understanding of chronic giardiasis (CG) may improve our care of patients in this stage of the disease. This review proposes a new concept of CG and highlights the recent advances in our understanding and management of this condition. According to this review, management requires, initially, an accurate diagnosis, which may exclude several conditions that can mimic CG. Optimal treatment requires a tailored approach which includes the recognition of the known modifiable causes of this health condition, assessment of symptoms and potential complications, their treatment utilizing, if necessary, a multidisciplinary team, and an ongoing monitoring for the effect of therapy - weighing the efficacy of individual drugs - all of these together may lead to a successful treatment of CG.

Update on the pathogenic potential and treatment options for Blastocystis sp

Although Blastocystis is one of the most common enteric parasites, there is still much controversy surrounding the pathogenicity and potential treatment options for this parasite. In this review we look at the evidence supporting Blastocystis as an intestinal pathogen as shown by numerous case studies and several in vivo studies and the evidence against. We describe the chronic nature of some infections and show the role of Blastocystis in immunocompromised patients and the relationship between irritable bowel syndrome and Blastocystis infection. There have been several studies that have suggested that pathogenicity may be subtype related. Metronidazole is the most widely accepted treatment for Blastocystis but several cases of treatment failure and resistance have been described. Other treatment options which have been suggested include paromomycin and trimethroprim- sulfamethoxazole.

Sexual transmission of giardiasis: a neglected route of spread?

Sexually transmitted infections (STIs) are often discussed in the context of syphilis, gonorrhea, herpes, chlamydiasis and AIDS. However, since the past 30 years of the last century, epidemiology and natural history studies have led to improved understanding of giardiasis as a STI, as a result of oral-anal sexual contact. Studies suggest that Giardia is an increasingly recognized infection that may be underdiagnosed under the STI context. Health care providers should maintain a high index of suspicion for Giardia, obtain suitable diagnostic tests to identify and screen those at high risk for this infection, institute appropriate therapy, counsel patients regarding treatment compliance, follow-up, encourage partner notification and teach strategies for preventing the transmission of this disease, including the discussion of the risk of enteric infections after oral-anal sexual contact. We summarize some data concerning the research and clinical literature on Giardia infection as a STI and identify the specific recommendations for control of giardiasis as STI that available evidence indicates can reduce its transmission.

Study of opportunistic intestinal parasitic infections in human immunodeficiency virus/acquired immunodeficiency syndrome patients

Introduction:

Intestinal parasites predominantly coccidian parasites are a common cause for diarrhea in human immunodeficiency virus (HIV)-positive patients.

Materials and Methods:

The study was conducted during January 2009-December 2010. A total of 1,088 stool samples from 544 seropositive HIV positive cases were examined microscopically for ova and cyst using wet mount preparations and stained smears. Out of 544 patients, 343 had prolonged diarrhea for more than 4 weeks, 57 had acute diarrhea of lesser than 7 days and 144 were asymptomatic cases who attended out-patient department; included in this study after taking consent from patients. Enteric pathogens were detected in 274 (50.36%) of the 544 patients.

Results and Conclusions:

The parasites identified were Cryptosporidium (135), Isospora belli (42), Cyclospora (12), Microsporidia (02), Entamoeba histolytica (49), Hookworm (34). Intestinal parasites in chronic diarrhea were significantly higher than the acute diarrhea (63.05% vs. 7.35%; P < 0.05). Parasitic pathogens were frequently associated with HIV-positive patients with diarrhea in Western India. Stools of all HIV-positive patients with diarrhea should thoroughly be investigated to identify etiologic agents for proper management.

Materials and Methods:

The study was conducted during January 2009-December 2010. A total of 1,088 stool samples from 544 seropositive HIV positive cases were examined microscopically for ova and cyst using wet mount preparations and stained smears. Out of 544 patients, 343 had prolonged diarrhea for more than 4 weeks, 57 had acute diarrhea of lesser than 7 days and 144 were asymptomatic cases who attended out-patient department; included in this study after taking consent from patients. Enteric pathogens were detected in 274 (50.36%) of the 544 patients.

Results and Conclusions:

The parasites identified were Cryptosporidium (135), Isospora belli (42), Cyclospora (12), Microsporidia (02), Entamoeba histolytica (49), Hookworm (34). Intestinal parasites in chronic diarrhea were significantly higher than the acute diarrhea (63.05% vs. 7.35%; P > 0.05). Parasitic pathogens were frequently associated with HIV-positive patients with diarrhea in Western India. Stools of all HIV-positive patients with diarrhea should thoroughly be investigated to identify etiologic agents for proper management.

Management of protozoa-related diarrhea in HIV infection

Protozoa infections are an important cause of chronic diarrhea in patients infected with HIV. The introduction of highly active antiretroviral treatment to the management of HIV in the mid 1990s has led to a dramatic reduction in the incidence of these opportunistic infections in Europe and America. In contrast, in the developing world where such treatments are not readily affordable, protozoa-related diarrhea remains a major cause of morbidity and mortality in HIV-infected individuals. In this review, the optimum investigations required to diagnose these pathogens in HIV-related diarrhea, as well as current treatment options, will be discussed.

High prevalence of diarrhoegenic intestinal parasite infections among non-ART HIV patients in Fitche Hospital, Ethiopia

BACKGROUND

HIV infection has been modifying both the epidemiology and outcome of parasite infections. Hence, this study was undertaken to determine the prevalence of Cryptosporidium and other intestinal parasite infections among HIV positives with and without Antiretroviral Treatment(ART) and its association with CD4+ T-cell count.

METHODS

A cross-sectional study was conducted at Fitche hospital focusing on HIV positives who came to hospital for follow-ups. A total of 378 HIV positive persons with and without ART participated in the study. Data on socio-demographic factors and diarrhoea status were obtained by interviewing all 214 with ART and 164 without ART. Stool samples were collected from all patients and examined for intestinal parasites using direct, formol-ether and modified acid-fast staining techniques.

RESULTS

The prevalence of intestinal parasite infections in this study was significantly higher among HIV positive persons not on ART. Specifically, the rate of infection with Cryptosporidium species, Blastocystis spp., Giardia lamblia, and Entamoeba histolytica/E. dispar were higher, particularly in those with CD4+ T-cell counts less than 200 cells/µL. Fifty seven percent of the study participants were on ART. Out of these 164/378 (43%) of the non-ART study participants were infected with at least one intestinal parasite species. Significant association was observed between lower CD4+ T-cell count (<200 cells/µL) and the prevalence of Cryptosporidium spp. and Blastocystis spp. The two parasites were significantly more prevalent in HIV positive non-ART patients.

CONCLUSION

HIV infection increased the risk of having Cryptosporidium and other intestinal parasites and diarrhoea. Therefore, raising HIV positive's immune status and screening for intestinal parasites is important. This study showed that patients who are taking ART had a lower prevalence of diarrhoea causing parasites and Cryptosporidium suggesting that ART through improvement of immune status of the patients may have contributed to controlling diarrhoea-causing parasites in HIV positive patients.

Differences in the detection of Cryptosporidium and Isospora (Cystoisospora) oocysts according to the fecal concentration or staining method used in a clinical laboratory

Despite the availability of many parasitological methods for detection of Cryptosporidium and Isospora (Cystoisospora) belli in fecal samples, there are uncertainties about the accuracy of these techniques in laboratory practice. In this study, 27 formalin-fixed positive stool samples for Cryptosporidium and 15 for I. belli were analyzed by 2 concentration methods, sedimentation by centrifugation (SC) and formalin-ethyl acetate (FE), and by 3 tintorial techniques, modified Ziehl-Neelsen (ZN), safranin (SF), and auramine (AR). No significant differences were observed on Cryptosporidium identification between concentration methods, while a significantly higher number of I. belli oocysts (P < 0.0001) was detected in fecal smears concentrated by the SC than by the FE method. Fecal samples processed by FE produced a median oocyst loss to the fatty ring of 34.8% for Cryptosporidium and 45.4% for I. belli. However, FE concentration provided 63% of Cryptosporidium and 100% of I. belli slides classified as superior for microscopic examination. Regarding the efficiency of staining methods, a more significant detection of Cryptosporidium oocysts was observed in fecal smears stained by ZN (P < 0.01) or AR (P < 0.05) than by the SF method. Regular to high-quality slides for microscopic examination were mostly observed in fecal smears stained with AR or ZN for Cryptosporidium and with SF or ZN for I. belli. This study suggests a great variability in oocyst power detection by routine parasitological methods, and that the most frequent intestinal coccidians in humans have specific requirements for concentration and staining.

Strongyloides stercoralis disseminated infection and schistosomiasis in an AIDS patient

Strongyloides stercoralis hyperinfection syndrome is classically associated with impaired host response and implies in an overburden of larvae in its usual cycle. It has been recognized as a severe and potentially fatal condition in immunocompromised individuals, especially those using oral corticosteroids. Infection with Schistosoma mansoni not only increases the susceptibility to HIV infection, but also promotes progression to disease. The association of the most severe forms of strongyloidiasis and AIDS is scarcely described, even more when S. mansoni is also associated. The authors describe a case of a 34-year-old previously healthy male, admitted to the emergency department with a history of hematemesis associated with dyspnea, hemoptysis, and fever. He referred homosexual relations for 6 years. Physical examination showed an ill-looking patient, and was remarkable for tachycardia, tachypnea, diaphoresis, and pulse oximetry of 70% in room air. Lungs examination revealed the presence of rales in the left base. Chest radiography showed a diffuse and bilateral reticulo-nodular pattern. HIV serology was positive. Empirical antimicrobial therapy and corticosteroids were initiated. On the third day of hospitalization, petechiae appeared over the periumbilical area, but no further investigation was undertaken because the patient died soon after. The autopsy findings were compatible with S. stercoralis disseminated infection, a hepatic intestinal chronic form of schistosomiasis, and septic shock as the primary cause of death. The authors call attention to this infrequent association.

Enteric parasites in HIV-1/AIDS-infected patients from a Northwestern São Paulo reference unit in the highly active antiretroviral therapy era

INTRODUCTION: We describe the epidemiology of intestinal parasites in patients from an AIDS reference service in Northeastern São Paulo, Brazil. METHODS: Retrospective evaluation was done for all HIV-1/AIDS-positive patients whose Hospital de Base/São José do Rio Preto laboratorial analysis was positive for enteroparasites after diagnosis of HIV-1 infection, from January 1998 to December 2008. Statistical analysis was performed using the R statistical software version 2.4.1. The level of significance adopted was 5%. RESULTS: The most frequent protozoan was Isospora belli (4.2%), followed by Giardia lamblia (3.5%), Entamoeba coli (2.8%), and Cryptosporidium parvum (0.3%). Ancylostoma duodenale (1.4%) was the most frequently detected helminth, while Taenia saginata and Strongiloides stercoralis were found in 0.7% of the samples. The results showed that diarrhea was significantly associated with giardiasis and isosporiasis. However, no association was observed between CD4+ cell counts, viral load, and the characteristics of any particular parasite. CONCLUSIONS: Our data may be useful for further comparisons with other Brazilian regions and other developing countries. The data may also provide important clues toward improving the understanding, prevention, and control of enteric parasites around the world.

Epidemiological aspects of strongyloidiasis in Brazil

The objective of this review was to outline an epidemiological profile of Strongyloides stercoralis by parasitological and serological diagnosis in inhabitants, and to associate this profile with different immunosupression situations, in Brazil, over 20 years (1990-2009). The occurrence of S. stercoralis using parasitological methods was 5·5%, being 4·8% in rural and 5·0% in urban areas, characterizing the country as hyperendemic. There was a diversity of techniques used as a diagnostic tool and only 39·1% of the studies presented results based on at least 1 specific method. The occurrence increased with age, being 12·1%, for those over 60 that suggests an epidemiological condition of concern for the elderly population. Of the seroepidemiological studies in the general population the mean positivity in serum samples was 21·7% and 29·2%, using an immunofluorescence antibody test and enzyme-linked immunosorbent assay (ELISA), respectively. The occurrence of strongyloidiasis in immunosuppressed individuals was 11·8% by parasitological methods and 19·5% using immunological methods. Considering that Brazil is a tropical country and that the character of chronicity and autoinfection of the parasite that can result in severe forms of hyperinfection or dissemination makes strongyloidiasis an important medically and socially neglected problem.

Update on strongyloidiasis in the immunocompromised host

Immunocompromised persons are the most vulnerable population at risk for developing life-threatening clinical syndromes associated with strongyloidiasis, such as hyperinfection syndrome (HS) or dissemination. This review focuses on describing Strongyloides infection in the immunocompromised host, including immune response against this infection, analyzing the cases with HS published during the past 4 years in the United States, and describing the most sensitive diagnostic tools and the most effective treatment for each clinical syndrome. Strongyloidiasis is becoming an important parasitic disease in the United States, especially in the immunocompromised immigrant population. Because the transplant population is particularly at risk for developing HS, both recipients and donors should be screened for Strongyloides. Clinicians should also be aware that the development of HS can follow unexpectedly a few days after appropriate anthelminthic therapy. Highly sensitive screening tests are still not available in the major tertiary medical centers. Parenteral ivermectin has been used in some severe cases. Further therapy developments and improving diagnostic tools are warranted.

Prevalence of intestinal parasites and profile of CD4+ counts in HIV+/AIDS people in north of Iran, 2007-2008

In this study 142 stool samples (64 HIV+/AIDS patients and 78 non-HIV infected individuals) collected from Mazandaran province and screened for intestinal parasites, using direct wet mont, formalin-ether sedimentation concentration, modified Ziehl Neelsen and modified trichrome techniques. Each person in this study was examined for CD4+ counts. Intestinal parasites were found in 11/64 (17.2%) of patients in HIV+/AIDS group and in 14/78 (17.9%) of controls. Prevalence of parasites detected in HIV+/AIDS individuals was as follow: Cryptosporidium sp. 9.4%, Giardia lamblia 3.1%, Entamoeba coli 1.6%, E. histolytica 1.6% and Chilomastix mesnili 1.6%. Prevalence of parasites in controls was as follow: Trichostrongylus sp. 6.4%, G. lamblia 3.8%, Cryptosporidium sp. 2.5%, E. coli 2.5%, E. histolytica 1.2%, Hookworms 1.2%. The mean of CD4+ counts in HIV-positive group (430 cells microL(-1)) was remarkedly less than controls (871 cells microL(-1)) (p = 0.001). As patients usually belong to poor socio-economic backgrounds and they can hardly afford treatment, therefore, it is suggested screening and free treatment of intestinal parasites in these individuals should be taken by health centers to prevent the occurrence of these diseases in HIV+/AIDS patients, as often the disease may take a fulminant form.

Intestinal parasites infection among immunocompromised patients in Riyadh, Saudi Arabia

This study was conducted to determine the prevalence of intestinal parasites among immunocompromised patients in Riyadh, Saudi Arabia. Fecal samples were collected from 136 immunocompromised patients (52 females and 84 males), aged 2 to 69 years. Specimens were fixed with 10% formalin for 30 min (2-3 g fecal(-1)) and then concentrated by a formalin-ether sedimentation technique. Samples were examined as wet saline mounts and in iodine preparation for detection of protozoan oocysts, cysts, helminthic eggs and larvae. Permanent stained smears were performed for intestinal coccidian parasites by the modified Ziehl-Neelsen technique and the modified trichrome stain. Intestinal parasites were detected in 54 (39.7%) most of them (25.7%) were with diarrhea. More specifically the following parasites were detected Cryptosporidium parvum 11(8.1%), Giardia lamblia 9 (6.6%), Cyclospora cayetanensis 8 (5.9%), Blastocystis hominis 7 (5.2%), Entamoeba histolytica 7 (5.2%), Entamoeba coli 5 (3.7%), Strongyloides stercoralis 3 (2.2%), Ascaris lumbricoides 1 (0.7%), Hymenolepis nana 1 (0.7%), Dicrocoelium dendriticum 1 (0.7%) and Hook worm 1 (0.7%). The most common parasite associated with diarrhea in patients, was C. parvum (p < 0.001), followed by G. lamblia, C. cayetanensis and E. histolytica. However, differences between different age groups were statistically non-significant. Similarly, no significant difference in the infection rate were found between male and female patients.

[Enteropathogens relating to diarrhea in HIV patients on antiretroviral therapy]

The etiology of the diarrheic process in AIDS may be caused by viruses, bacteria, fungi, protozoa or helminths, as well as HIV itself. This study evaluated enteropathogens relating to diarrhea in HIV patients who were on antiretroviral therapy. The parasitological methods used were Faust, Hoffmann and Kinyoun. Isolation and culturing of fungi were carried out in accordance with the methodology recommended by the NCCLS M27-A standard. The yeast species were identified using the polymerase chain reaction (PCR). Bacteria were isolated on MacConkey and SS agar and the species were identified using Enterokit B (Probac do Brasil) and biochemical methods. Forty-nine patients were evaluated: 44.89% presented enteroparasites and 48.1% presented Candida sp, of which 61.5% were Candida albicans, 7.6% were Candida sp and 30.7% were Candida non-albicans. Bacteria were isolated from 72% of the patients, of which 49% were Escherichia coli, 13% Salmonella parathyphi, Klebsiella sp or Proteus and 6% Citrobacter freundii or Yersinia sp. There was high prevalence of Candida sp in HIV patients with diarrhea and non-albicans species were isolated. Their presence could be taken to mean that they were accomplices in or causes of the infection.

Clinical significance of enteric protozoa in the immunosuppressed human population

Globally, the number of immunosuppressed people increases each year, with the human immunodeficiency virus (HIV) pandemic continuing to spread unabated in many parts of the world. Immunosuppression may also occur in malnourished persons, patients undergoing chemotherapy for malignancy, and those receiving immunosuppressive therapy. Components of the immune system can be functionally or genetically abnormal as a result of acquired (e.g., caused by HIV infection, lymphoma, or high-dose steroids or other immunosuppressive medications) or congenital illnesses, with more than 120 congenital immunodeficiencies described to date that either affect humoral immunity or compromise T-cell function. All individuals affected by immunosuppression are at risk of infection by opportunistic parasites (such as the microsporidia) as well as those more commonly associated with gastrointestinal disease (such as Giardia). The outcome of infection by enteric protozoan parasites is dependent on absolute CD4(+) cell counts, with lower counts being associated with more severe disease, more atypical disease, and a greater risk of disseminated disease. This review summarizes our current state of knowledge on the significance of enteric parasitic protozoa as a cause of disease in immunosuppressed persons and also provides guidance on recent advances in diagnosis and therapy for the control of these important parasites.

Etiological agents of diarrhea in patients infected by the human immunodeficiency virus-1: a review

Despite the importance of understanding the epidemiology of agents responsible for infectious diarrhea in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) population, the number of articles about this subject is relatively few. The current article summarizes published data on bacterial, fungal, viral and parasitic enteropathogens in the HIV/AIDS seropositive subjects in different countries, regions and localities. In general, there is a great difference in the frequencies of etiological agents due to factors which include immune status, geographical location, climate and socioeconomic conditions. It is important to stress that a great prevalence of infection by emergent agents has been reported in the more advanced stages of AIDS. Therefore, to establish specific treatment depends directly on knowledge of these agents and risk factors associated to their distribution. Moreover, the colonization by potential pathogenic agents verified in these individuals is high thus implicating that they act as carriers. Finally, public health measures of control and prevention must take into consideration the regional previously identified enteropathogens, especially in areas where HIV prevalence is high.

Intestinal parasitic infections in HIV/AIDS patients presenting with diarrhoea in Jakarta, Indonesia

We investigated the occurrence of intestinal parasites in Indonesian HIV/AIDS patients with chronic diarrhoea prior to administering antiretroviral therapy. The influence of age, CD4(+) cell count and season on parasite occurrence was also studied. In total, 318 unconcentrated stool samples were analysed using Lugol's iodine and modified acid fast staining to detect intestinal coccidia. Most samples (94.5%) were from males aged 21-40 years with CD4(+) counts < or = 50 cells/mm(3). Parasites were found in 84.3% of samples (single species infections, 71.4%; polyparasitism, 12.9%), with protozoan pathogens occurring most commonly. Cryptosporidium (4.9%), Cyclospora cayetanensis (4.5%) and Giardia duodenalis (1.9%) were the most frequent single infections, but Blastocystis hominis (72.4%) was the most commonly occurring protist. Cryptosporidium and C. cayetanensis occurred in 11.9% and 7.8% of all (single and mixed) infections. The most common co-infection was with B. hominis and Cryptosporidium (6.3%). Intestinal protozoan pathogens were detected more frequently in cases with CD4(+) counts < or = 200/mm(3). No seasonal influence was determined for Cryptosporidium, C. cayetanensis or B. hominis, but gross seasonal disturbances may have influenced our findings. Intestinal parasites should be looked for routinely in this group of individuals and should be treated to reduce complications and the likelihood of transmission.

Genotypic identification of Cryptosporidium spp. isolated from HIV-infected patients and immunocompetent children of São Paulo, Brazil

Cryptosporidium isolates identified in fourteen stool samples, collected from five HIV-infected patients and nine immunocompetent children, living in the State of São Paulo, Brazil, were submitted to a molecular analysis using a nested PCR followed of restriction fragment length polymorphism (RFLP), for genetic characterization. The analysis was based on digestion with RsaI restriction enzyme of a DNA fragment amplified from the Cryptosporidium oocyst wall protein (COWP) gene. Based on this analysis, four samples were identified as Cryptosporidium parvum, eight as Cryptosporidium hominis and two presented a profile that corresponded to Cryptosporidium meleagridis when compared to the standards used in the analysis. The use of molecular methods can be helpful to identify source of infections and risk factors related to Cryptosporidium infection in our communities.

Giardiasis: a pharmacotherapy review

Giardia lamblia, the cause of human giardiasis, is among the most common intestinal protozoa worldwide. Human infection may range from asymptomatic shedding of giardial cysts to symptomatic giardiasis, being responsible for abdominal cramps, nausea, acute or chronic diarrhoea, with malabsorption and failure of children to thrive. At present, treatment options include the nitroimidazoles derivatives; especially metronidazole, which has been the mainstay of treatment for decades and is still widely used. The increasing number of reports of refractory cases with this group of drugs and other antigiardial agents, has raised concern and led to a search for other compounds, some of which have arisen due to the introduction of drugs initially addressed to other diseases. The present article examines some of the most important points of antigiardial pharmacotherapy available at present and the future prospects of development of new agents.

Bacterial, yeast, parasitic, and viral enteropathogens in HIV-infected children from São Paulo State, Southeastern Brazil

We present here the frequency of enteropathogens in an HIV-infected children group and investigate their correlation with clinical and sociodemographic characteristics by collecting 100 stool samples from 55 HIV-seropositive Brazilian children. All specimens were processed according to standard methods for bacterial and yeast detection. A commercially available enzyme-linked immunosorbent assay was used to detect protozoan, and to perform virus detection, molecular tests were applied. Consumption of raw vegetables and fruits and severe immunosuppression were significantly associated with diarrhea. Cryptosporidium parvum was the commonest enteropathogen, followed by Candida albicans, enteropathogenic Escherichia coli, and astrovirus. The number of potential pathogenic agents identified in fecal specimens in asymptomatic HIV-seropositive infants is high, which raises the need for additional investigation in this area as well as in other Brazilian regions.

Diagnóstico laboratorial de enteroparasitoses oportunistas, com ênfase nas microsporidioses humanas, em Goiânia-GO

Os microsporídios são protozoários, emergentes e oportunistas, responsáveis por patologias de alta morbi-mortalidade, principalmente em indivíduos com distúrbios imunes. Este estudo visa determinar o perfil clínico-laboratorial destes agentes. No total, foram avaliados 723 pacientes divididos em dois grupos: I) Indivíduos imunodeprimidos/imunossuprimidos; II) Indivíduos aparentemente imunocompetentes. Estes, após livre e esclarecido consentimento, foram entrevistados e cederam amostras fecais, sendo todas submetidas a técnicas de HPJ, Rugai, Faust e colorações específicas para coccídios e microsporídios. A freqüência de microsporídios foi 1,3% (5/393) no grupo I, enquanto no outro grupo foi quatro vezes menor. A ocorrência de outras enteroparasitoses oportunistas também foi maior no grupo I. Conclui-se, por um lado, que estes agentes estão em nosso meio, e por outro, necessitamos aprimorar o diagnóstico clínico e laboratorial, para definir a distribuição geográfica destes agentes no Estado de Goiás e no Brasil.

Infection by Cryptosporidium sp. in immunocompromised haematological patients

The frequency of intestinal infection by Cryptosporidium sp. was determined in 60 patients, attended at the Haematological and Haemotherapeutical Service of "Santa Casa de Misericórdia" of São Paulo, suffering lymphoproliferative diseases (Group 1). As control group (Group 2) 59 persons without haematological diseases, but with the same life time and living at the same place of that of haematological patients, had been examined. The stool parasitological tests performed disclosed Cryptosporidium sp. oocysts in six (10%) individuals belonging to Group 1, whereas, in Group 2, nobody showed infection by this coccidian. Among the patients infected by Cryptosporidium sp. only one showed diarrhoeal faeces.

Blastocystis hominis and other intestinal parasites in a community of Pitanga City, Paraná State, Brazil

The objective was to estimate the prevalence of Blastocystis hominis, to evaluate the effectiveness of different techniques for its diagnosis as well as to estimate the prevalence of other intestinal parasites in the community of Campo Verde, a district of Pitanga. The work was carried out from August to October 2004. Samples of feces from children and adults were collected and submitted to the techniques of direct wet mount, flotation in zinc sulphate solution, tube sedimentation, sedimentation in formalin-ether and staining by Kinyoun and iron hematoxylin methods. From 181 studied individuals, 128 (70.7%) showed protozoa and/or helminths in stool samples. The most prevalent species were Endolimax nana (33.7%); B. hominis (26.5%); Giardia lamblia (18.2%); Entamoeba coli (17.1%); Ascaris lumbricoides (16.6%); Iodamoeba bütschlii (9.4%); and ancylostomatidae (7.7%). B. hominis was only identified by the techniques of direct wet mount, sedimentation in formalin-ether and staining by iron hematoxylin, though the latter was less sensitive than the other methods. The high frequency of B. hominis demonstrated by this study indicates the need to include laboratory techniques that enable identification of the parasite on a routine basis.

Diarrhea, CD4+ cell counts and opportunistic protozoa in Indian HIV-infected patients

The aim of this study was to examine the relationships among diarrhea, CD4+ cell counts and opportunistic protozoa in HIV-infected patients in North India. In a retrospective study, blood and stool samples of 200 HIV-infected patients from March 2001 until 2003, submitted to the AIDS division of National Institute of Communicable Diseases (NICD), were analyzed. Each patient was examined for opportunistic protozoa, HIV-1 status and CD4+ cell counts, and screened for diarrheal symptoms. The rate of diarrhea was 38% in the stool examination. In HIV-infected patients in the groups CD4+ > 500 cells/microL, 200 cells/microL < CD4+ < 500 cells/muL and in the AIDS patients CD4+ < 200 cells/microL, diarrhea was 14.7, 29.8 and 56.1%, respectively. It is clear that the diarrhea in the AIDS patients was significant compared with the two former groups (P < 0.0005). In the AIDS patients CD4+ < 200 cells/microL with diarrhea, Cryptosporidium infection was, at 56.5%, the highest and statistically significant compared with the other parasites (P = 0.037). Microsporidium was detected in 30.4% of the AIDS patients. Diarrhea was common and most strongly associated in patients with low CD4+ cell counts. The data stress the importance of opportunistic protozoa in the HIV-infected patients, and that opportunistic protozoa should be expected in HIV-infected patients with low CD4+ and diarrhea.

Imported strongyloidosis: a longitudinal analysis of 31 cases

BACKGROUND

Attention regarding imported tropical diseases is typically focused on malaria, although other parasitic diseases such as strongyloidosis may also cause serious health problems. The importance of assessing clinical features and of proper diagnosis and treatment is presented on the basis of 31 patients with imported strongyloidosis.

METHODS

A retrospective analysis was performed regarding patients treated for strongyloidosis in two referral centers in Switzerland from 1998 to 2002.

RESULTS

Imported strongyloidosis was investigated in 12 travelers and 19 immigrants. The reasons for diagnostic work-up were clinical symptoms in 84% and eosinophilia and screening in each of 22.5%. All patients had a history of travel or residence in endemic areas. Initial therapy was effective in 20 patients, and there was a tendency for a better response to ivermectin compared with the response to other drugs. A significant reduction in blood eosinophil count and serologic antibody titer was observed in patients responding to therapy after an average of 96 and 270 days, respectively.

CONCLUSIONS

Strongyloidosis must be suspected in travelers and immigrants with skin or abdominal symptoms from regions where Strongyloides stercoralis is highly endemic. The results of this case series confirm that ivermectin is the drug of choice in treating imported strongyloidosis. Response to therapy can be assessed by serology and differential white blood count performed over 6 months after therapy.

[Blastocystosis: nitazoxanide as a new therapeutic option]

We report a case of a patient with AIDS and severe immunosuppression who developed diarrhea due to a vacuolar stage of Blastocystis hominis. The patient was treated with nitazoxanide, a 5-nitrothiazole broad-spectrum antiparasitic agent. We obtained complete remission of symptoms and eradication of the parasite. Nitazoxanide is a new treatment option for blastocystosis in AIDS patients. Further studies to test its efficacy are needed.

Could control of soil-transmitted helminthic infection influence the HIV/AIDS pandemic

In May 2001, the World Health Assembly (WHA) estimated that two billion people were infected by soil-transmitted helminths (S-THs) and schistosomiasis, worldwide. The WHA urged member states to recognise that there can be synergy between public health control programmes for S-THs, schistosomiasis and other diseases. This is particularly relevant to the new dimension created by the HIV/AIDS epidemics in the same impoverished communities and countries where helminthiasis is hyperendemic. Immunological adaptation between humans and parasitic helminths has developed during evolution. Review of 109 research papers, 76% (83/109) of which, were published between 1995 and February 2002, revealed increasing evidence that this relationship may have created an opportunity for more rapid infection by the human immunodeficiency virus (HIV), as well as quicker progression to AIDS. Moreover, the efficacy of some vaccines against HIV is likely to be impaired by chronic helminthiasis. For this, there is strong, indirect evidence. There is an urgent need for parasitologists, epidemiologists, immunologists and virologists to undertake comprehensive, transdisciplinary research. On the other hand, there is no current evidence that immunosuppression by HIV facilitates helminthic infection. The situation in regard to strongyloidiasis, however, is not yet clear.

Evaluation of lacto-phenol cotton blue (LPCB) for detection of Cryptosporidium, Cyclospora and Isospora in the wet mount preparation of stool

Lacto-phenol cotton blue (LPCB) was found to be a useful stain for detection of Cyclospora and Isospora oocysts in direct wet mounts of stool. LPCB stained these parasites blue, and differentiated their internal structures clearly, thereby facilitating detection and accurate identification of these parasites. However, the LPCB staining was not found useful in the identification of Cryptosporidium. The LPCB wet mount is recommended for use in the laboratories where acid-fast staining is not performed routinely, such as in a peripheral laboratory or in a rural health centre in the developing countries.

Epidemiological survey of Blastocystis hominis in Huainan City, Anhui Province, China

AIM: To provide scientific evidence for prevention and controlling of blastocystosis, the infection of Blastocystis homonis and to study its clinical significance in Huainan City, Anhui Province, China.

METHODS: Blastocystis homonis in fresh stools taken from 100 infants, 100 pupils, 100 middle school students and 403 patients with diarrhea was smeared and detected with method of iodine staining and hematoxylin staining. After preliminary direct microscopy, the shape and size of Blastocystis homonis were observed with high power lens. The cellular immune function of the patients with blastocystosis was detected with biotin-streptavidin (BSA).

RESULTS: The positive rates of Blastocystis homonis in fresh stools taken from the infants, pupils, middle school students and the patients with diarrhea, were 1.0% (1/100), 1.0% (1/100), 0% (0/100) and 5.96% (24/403) respectively. Furthermore, the positive rates of Blastocystis homonis in the stool samples taken from the patients with mild diarrhea, intermediate diarrhea, severe diarrhea and obstinate diarrhea were 6.03% (14/232), 2.25% (2/89), 0% (0/17) and 12.31% (8/65) respectively. The positive rates of Blastocystis homonis in fresh stools of male and female patients with diarrhea were 7.52% (17/226) and 3.95% (7/177) respectively, and those of patients in urban and rural areas were 4.56% (11/241) and 8.02% (13/162) respectively. There was no significant difference between them (P > 0.05). The positive rates of CD₃⁺, CD₄⁺, CD₈⁺ in serum of Blastocystis homonis-positive and-negative individuals were 0.64 ± 0.06, 0.44 ± 0.06, 0.28 ± 0.04 and 0.60 ± 0.05, 0.40 ± 0.05 and 0.30 ± 0.05 respectively, and the ratio of CD₄⁺/CD₈⁺ of the two groups were 1.53 ± 0.34 and 1.27 ± 0.22. There was significant difference between the two groups (P < 0.05, P < 0.01).

CONCLUSION: The prevalence of Blastocystis hominis as an enteric pathogen in human seems not to be associated with gender and living environment, and that Blastocystis hominis is more common in stool samples of the patients with diarrhea, especially with chronic diarrhea or obstinate diarrhea. When patients with diarrhea infected by Blastocystis hominis, their cellular immune function decreases, which make it more difficult to be cured.

Recent advances in Blastocystis hominis research: hot spots in terra incognita

Despite being discovered more than 80 years ago, progress in Blastocystis research has been gradual and challenging, due to the small number of laboratories currently working on this protozoan parasite. To date, the morphology of Blastocystis hominis has been extensively studied by light and electron microscopy but all other aspects of its biology remain little explored areas. However, the availability of numerous and varied molecular tools and their application to the study of Blastocystis has brought us closer to understanding its biology. The purpose of this review is to describe and discuss recent advances in B. hominis research, with particular focus on new, and sometimes controversial, information that has shed light on its genetic heterogeneity, taxonomic links, mode of transmission, in vitro culture and pathogenesis. We also discuss recent observations that B. hominis has the capacity to undergo programmed cell death; a phenomenon similarly reported for many other unicellular organisms. There are still many gaps in our knowledge of this parasite. Although there is a growing body of evidence suggesting that B. hominis can be pathogenic under specific conditions, there are also other studies that indicated otherwise. Indeed, more studies are warranted before this controversial issue can be resolved. There is an urgent need for the identification and/or development of an animal model so that questions on its pathogenesis can be better answered. Another area that requires attention is the development of methods for the transfection of foreign/altered genes into B. hominis in order to facilitate genetic experiments.

Diagnosis of Strongyloides stercoralis infection

Strongyloides stercoralis infects 30 million people in 70 countries. Infection usually results in asymptomatic chronic disease of the gut, which can remain undetected for decades. However, in patients receiving long-term corticosteroid therapy, hyperinfection can occur, resulting in high mortality rates (up to 87%). Strongyloidiasis is difficult to diagnose because the parasite load is low and the larval output is irregular. Results of a single stool examination by use of conventional techniques fail to detect larvae in up to 70% of cases. Several immunodiagnostic assays have been found ineffective in detecting disseminated infections and show extensive cross-reactivity with hookworms, filariae, and schistosomes. Although it is important to detect latent S. stercoralis infections before administering chemotherapy or before the onset of immunosuppression in patients at risk, a specific and sensitive diagnostic test is lacking. This review describes the clinical manifestations of strongyloidiasis, as well as various diagnostic tests and treatment strategies.

Gastrointestinal infections in the immunocompromised host

The gastrointestinal tract is a common site of infection in the opportunistic host. Pathogens range from highly virulent organisms, which infect people with well functioning immune systems as well as people with poorly functioning immune systems, to opportunistic organisms, which infect only those with impaired immune systems. Viruses, bacteria, fungi, and protozoa lead to disease that can be especially severe, debilitating, and difficult to treat in the immunocompromised host. Yet in this era of highly active antiretroviral therapy for HIV-infected patients and strategies to reduce immunosuppression in transplant and oncology patients, appropriate diagnostic tests and treatment can both improve the quality of life and decrease mortality. In this article, I review the changing pathogenesis, epidemiology, clinical presentation, diagnosis, and treatment of gastrointestinal infections in the immunocompromised host.