Epidemiology of infections with intestinal parasites and human immunodeficiency virus (HIV) among sugar-estate residents in Ethiopia

A systematic review and meta-analysis on prevalence and distribution of Taenia and Echinococcus infections in Ethiopia

Background

Tapeworm infections are among the tropical neglected parasitic diseases endemically occurring in Ethiopia. This systematic review and meta-analysis aims at estimating the pooled prevalence and distribution of Taenia and Echinococcus infections in humans and animals from reports from Ethiopia.

Methods

The systematic search was conducted in four bibliographic databases (PubMed, Google Scholar, Africa Journal Online and Science Direct). Additional data were retrieved from grey literature. Studies that met the inclusion criteria were considered for the systematic review and meta-analysis. The meta-analysis was conducted using MetaXL add-in for Microsoft Excel. Heterogeneity and inconsistency were evaluated using Cochran’s Q and I² statistics, respectively.

Results

The study provides a country-based database of Taenia and Echinococcus infections consisting of 311 datasets from 201 publications which were mostly abattoir surveys; of these, 251 datasets were subjected to meta-analysis. Most of the studies were from Oromia (32.8%) followed by Amhara (22.9%) regional states. The pooled prevalence of cystic echinococcosis in intermediate and accidental hosts was calculated as 22% (95% CI 18–26%) and high study variability (Q = 24,420.65, I² = 100%, P = 0.000). Moreover, a pooled prevalence of Echinococcus infections in final hosts was calculated as 33% (95% CI 20–48%) and low study variability (Q = 17.24, I² = 65%, P = 0.001). Similarly, study subjects (human, cattle, sheep, goat and wolf) were infected by Taenia spp. with pooled prevalence of 3% (95% CI 2–4%) and moderate study variability (Q = 279.07, I² = 89, P = 0.000). Meanwhile, the pooled prevalence of Taenia hydatigena, T. ovis and T. multiceps infections in intermediate hosts were calculated as 38%, 14% and 5%, respectively. The random effect meta-analysis of bovine cysticercosis showed a pooled prevalence of 7% (95% CI 5–9%) and high study variability was of (Q = 4458.76; I² = 99%, P = 0.000). Significant differences in prevalence of Taenia and Echinococcus infections between study sites or different livestock origins have been reported.

Conclusion

The study evidenced a comprehensive dataset on the prevalence and distribution of Taenia and Echinococcus infections at different interfaces by regions and hosts and hence can aid in the design of more effective control strategies.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04925-w.

Identification of risk areas and practices for Taenia saginata taeniosis/cysticercosis in Ethiopia: a systematic review and meta-analysis

Background

Bovine cysticercosis (BCC) is an infection of cattle with the metacestode stage of Taenia saginata, the beef tapeworm, which causes taeniosis in humans. BCC is responsible for considerable economic losses in the meat sector worldwide. This systematic review and meta-analysis summarizes the prevalence, risk factors and treatment efforts made so far on T. saginata infections in Ethiopia, providing a detailed analysis of different factors influencing the varying prevalence estimates in Ethiopia to gain more insight into the occurrence and risk factors of T. saginata taeniosis and cysticercosis to date.

Methods

A systematic review and meta-analysis was conducted on data collected from published and grey literature accessed through an electronic database and manual search.

Results

The literature search resulted in 776 outputs of which 132 conformed to the predefined criteria. The average zonal prevalence of meat inspection-based BCC ranged from 2% in Buno-Bedele to 24.6% in Sidama zone. The pooled prevalence of BCC was influenced by the number of muscle/organs inspected, ranging from 3.4% (95% CI: 1.7–5.1%) using fewer predilection sites to 19.4% (95% CI: 13.3–25.4%) using inspection of a maximum number of predilection sites. None of the tested variables were significantly associated with BCC. Questionnaire-based taeniosis ranged between 19.0% in Halaba special woreda to 70.0% in Gedeo zone and stool test-based taeniosis varied from 0.6% in central Tigray to 10.7% in Gurage zone. Questionnaire-based prevalence of taeniosis was higher in people with a frequent raw beef consumption habit (pooled OR, pOR: 10.5, 95% CI: 6.0–17.9), adults (pOR: 2.5, 95% CI: 1.7–3.6), men (pOR: 2.8, 95% CI: 2.1–3.6), and Christians (pOR: 2.0, 95% CI: 1.4–2.8) compared to less frequent raw beef consumers, younger people, women and Muslims, respectively.

Conclusions

This review revealed a widespread but variable occurrence of BCC and taeniosis in Ethiopian regions and zones, urging for harmonized and enhanced detection for improved control of the parasite. Accurate prevalence estimates using more sensitive tests, detailed risk factor analysis, as well as data on financial losses are needed to develop effective control strategies for the Ethiopian epidemiologic condition.

Epidemiology of Taenia saginata taeniosis/cysticercosis: a systematic review of the distribution in southern and eastern Africa

Background

The beef tapeworm, Taenia saginata, causing cysticercosis in bovines and taeniosis in humans, is thought to have a global distribution. In eastern and southern Africa, cattle production plays a crucial role in the economy, but a clear overview of the prevalence of T. saginata in the region is still lacking. This review aims to summarize existing knowledge on T. saginata taeniosis and bovine cysticercosis distribution in eastern and southern Africa.

Methods

A systematic review was conducted, that gathered published and grey literature, including OIE reports, concerning T. saginata taeniosis and bovine cysticercosis in eastern and southern Africa published between January 1st, 1990 and December 31st, 2017.

Results

A total of 1232 records were initially retrieved, with 78 full text articles retained for inclusion in the database. Unspecified taeniosis cases were reported for Angola, Ethiopia, Kenya, Madagascar, Malawi, South Africa, Tanzania, Uganda and Zambia, whereas T. saginata taeniosis cases were found for Ethiopia, Kenya, South Africa, Tanzania, Zambia and Zimbabwe. The prevalence of taeniosis ranged between 0.2–8.1% based on microscopy, and between 0.12–19.7% based on coproAg-ELISA. In Ethiopia, the percentage of tapeworm self-reporting was high (45.0–64.2%), and a substantial number of anthelmintic treatments were reported to be sold in towns. The presence of bovine cysticercosis was reported in all 27 countries/territories included in the study, except for Rwanda and Somalia, Comoros, Madagascar, Mauritius, Mayotte, Seychelles and Socotra. The prevalence of cysticercosis ranged between 0.02–26.3% based on meat inspection, and between 6.1–34.9% based on Ag-ELISA.

Conclusions

Although T. saginata has been reported in the majority of countries/territories of the study area, T. saginata taeniosis/cysticercosis remains a largely ignored condition, probably due to the absence of symptoms in cattle, the lack of data on its economic impact, and the fact that human taeniosis is considered a minor health problem. However, the occurrence of bovine cysticercosis is a clear sign of inadequate sanitation, insufficient meat inspection, and culinary habits that may favour transmission. Measures to reduce transmission of T. saginata are therefore warranted and the infection should be properly monitored.

Electronic supplementary material

The online version of this article (10.1186/s13071-018-3163-3) contains supplementary material, which is available to authorized users.

Evaluation of Parasitological Methods for the Detection of Strongyloides Stercoralis among Individuals in Selected Health Institutions In Addis Ababa, Ethiopia

Background

Strongyloides stercoralis causes chronic intestinal infection that may lead to disseminated disease during immunosuppression. Therefore, efficient diagnostic methods are essential to detect silent and latent infections. The present study was aimed to compare the efficacy of parasitological methods for the detection of S. stercoralis infection.

Methods

A cross-sectional study was conducted on 351 subjects (226 HIV positive and 125 HIV negative) from October 2005 to May 2006. The study participants were selected by systematic random sampling method. Fresh fecal samples were collected from each participant and processed by different parasitological methods.

Results

Among the 351 individuals involved in the study, 43(12.3%) were infected by S. stercoralis. The prevalence of S. stercoralis infection was significantly higher among HIV positive subjects (17.3%) as compared with 3.2% in HIV negative subjects (p=0.001). The odd of being infected by S. stercoralis was significantly higher among AIDS patients (OR=6.31; 95% CI, 2.2–18.1) and HIV patients with diarrhea (OR=9.3; 95% CI 4.6–18.9) as compared with respective controls. Agar plate culture showed superior sensitivity (97.7%) than other methods for detection of S. stercoralis. Similarly, agar plate culture showed strong diagnostic agreement with Baermann's method (kappa = 0.82; 95% CI 0.72 – 0.92) followed by fecal concentration (kappa= 0.67; 95% CI=0.54–0.80).

Coclusion

This study revealed that HIV patients were about 6 folds susceptible for S. stercoralis infection. Similarly, agar plate culture showed superior diagnostic efficiency for detections of S. stercoralis infection.

van Dam G, Corstjens PL, Hughes P, Ding S, Pantaleo G, Kaleebu P, Elliott AM, Kamali A. Effect of high-intensity versus low-intensity praziquantel treatment on HIV disease progression in HIV and Schistosoma mansoni co-infected patients: a randomised controlled trial

Background: It has been hypothesised that Schistosoma co-infection exacerbates HIV progression, and hence anthelminthic intervention in co-infected individuals will delay it. We evaluated effects of high-intensity versus low-intensity praziquantel treatment of schistosomiasis on HIV disease progression among co-infected patients from fishing populations around Lake Victoria, Uganda. Methods: Between August 2012 and September 2015, we conducted an open-label randomised, controlled trial. Adults, antiretroviral therapy-naïve, CD4 counts ≥350 cells/μl, HIV and S. mansoni co-infected, were randomised 1:1 to praziquantel (40mg/kg) given quarterly (starting at enrolment) or annually (starting 12 weeks after enrolment; such that low-intensity participants were still untreated when sampled at 12 weeks). A non-randomised HIV-positive S. mansoni-negative comparison group was recruited. The primary outcome was mean change in plasma viral load at 12 and 60 weeks. Results: In total 363 participants (high-intensity 113, low-intensity 113, comparison group 137) were recruited; 96 (85.0%), 97 (85.8%) and 107 (78.1%) completed 60 weeks of follow up, respectively. Adjusting for baseline age and viral load, the geometric mean ratio (aGMR [95%CI]) viral load for high-intensity vs low-intensity groups at 12 weeks was 0.90 [0.65, 1.25] p=0.55 and at 60 weeks 1.88 [0.78, 4.53] p=0.16. Results in the comparison group were similar to trial arms. High-intensity, compared to low-intensity, treatment resulted in substantially lower S. mansoni prevalence at all follow up visits (p<0.05). Conclusions: In communities with a high burden of both S. mansoni and HIV infection, high-intensity treatment of S. mansoni does not delay HIV progression despite relevant benefit for parasite clearance. Trial registration: ISRCTN15371662 (17/11/2016).

Prevalence of Strongyloides stercoralis and Other Intestinal Parasite Infections in School Children in a Rural Area of Angola: A Cross-Sectional Study

Strongyloides stercoralis is widely distributed in the tropics and subtropics. The aim of this study was to determine the prevalence of S. stercoralis and other intestinal parasites and identify the risk factors for infection with S. stercoralis in a rural area of Angola. A cross-sectional study was conducted in school-age children (SAC) in Cubal, Angola. A questionnaire collecting clinical and epidemiological variables was used, and two stool samples were collected. A concentration technique (Ritchie) and a technique for detection of larvae migration (Baermann) were performed. Of 230 SAC, 56.1% were female and the mean age was 9.3 years (SD 2.45). Severe malnutrition, according to body mass index (BMI)-for-age, was observed in 20.4% of the SAC, and anemia was found in 59.6%. Strongyloides stercoralis was observed in 28 of the 230 (12.8%) SAC. Eggs of other helminths were observed in 51 (22.2%) students: Hymenolepis spp. in 27 students (11.7%), hookworm in 14 (6.1%), Schistosoma haematobium in four (1.7%), Enterobius vermicularis in four (1.7%), Ascaris lumbricoides in three (1.3%), Taenia spp. in two (0.9%), and Fasciola hepatica in one (0.4%). Protozoa were observed in 17 (7.4%) students. Detection of S. stercoralis was higher using the Baermann technique versus using formol-ether (11.3 vs. 3%). Overall prevalence of S. stercoralis in the school population of 16 studied schools in the municipal area of Cubal was greater than 10%. This fact must be considered when designing deworming mass campaigns. The use of specific tests in larvae detection is needed to avoid overlooking this parasite.

Coccidian intestinal parasites among immunocompetent children presenting with diarrhea: Are we missing them?

BACKGROUND

Diarrhoea is an important cause of both morbidity and mortality among children in India. Coccidian parasitic infections are an important cause of diarrhea in immunocompromised patients, but their investigations are rarely sought by the treating physicians in seemingly immunocompetent children. This study was aimed to find the incidence rate of coccidian parasites in all children presented with diarrhoea, irrespective of their immune status.

MATERIALS AND METHODS

Between December 2015 and May 2016, all fecal samples from children aged between 0 and 15 years presenting with diarrhoea, irrespective of their immune status, were examined using conventional wet mount and modified acid-fast staining. At the end of the study, records of their clinical history and immune status including HIV positivity were evaluated. Findings of wet-mount and modified acid-fast stained smear microscopy were analyzed in relation with clinical details.

RESULTS

During the study, samples from 200 children (single sample) with diarrhea were processed. Their mean age was 5.7 ± 3.3 years (range 4-168 months). Seventeen out of 200 (8.5%) samples were positive for acid-fast coccidian parasites. Eight (4%) samples were found to be positive for Cryptosporidium hominis, while 5 (2.5%) were positive for Cyclospora cayetonensis and 4 (2%) samples for Isospora belli oocysts. Half (50%) of the children who were tested positive for Cryptosporidium and Cyclospora were found to be otherwise immunocompetent. However, all four cases of Isosporiasis were immunocompromised patients.

CONCLUSION

We highlight the high incidence of coccidian parasites among immunocompetent children with diarrhea. The clinicians need to be aware that coccidian parasites are a potential cause of childhood diarrhea even in immunocompetent children.

Determining intestinal parasitic infections (IPIs) in inmates from Kajang Prison, Selangor, Malaysia for improved prison management

BACKGROUND

The prison management in Malaysia is proactively seeking to improve the health status of the prison inmates. Intestinal parasitic infections (IPIs) are widely distributed throughout the world and are still gaining great concern due to their significant morbidity and mortality among infected humans. In Malaysia, there is a paucity of information on IPIs among prison inmates. In order to further enhance the current health strategies employed, the present study aims to establish firm data on the prevalence and diversity of IPIs among HIV-infected and non-HIV-infected individuals in a prison, an area in which informed knowledge is still very limited.

METHODS

Samples were subjected to microscopy examination and serological test (only for Strongyloides). Speciation for parasites on microscopy-positive samples and seropositive samples for Strongyloides were further determined via polymerase chain reaction. SPSS was used for statistical analysis.

RESULTS

A total of 294 stool and blood samples each were successfully collected, involving 131 HIV positive and 163 HIV negative adult male inmates whose age ranged from 21 to 69-years-old. Overall prevalence showed 26.5% was positive for various IPIs. The IPIs detected included Blastocystis sp., Strongyloides stercoralis, Entamoeba spp., Cryptosporidium spp., Giardia spp., and Trichuris trichiura. Comparatively, the rate of IPIs was slightly higher among the HIV positive inmates (27.5%) than HIV negative inmates (25.8%). Interestingly, seropositivity for S. stercoralis was more predominant in HIV negative inmates (10.4%) compared to HIV-infected inmates (6.9%), however these findings were not statistically significant. Polymerase chain reaction (PCR) confirmed the presence of Blastocystis, Strongyloides, Entamoeba histolytica and E. dispar.

CONCLUSIONS

These data will enable the health care providers and prison management staff to understand the trend and epidemiological situations in HIV/parasitic co-infections in a prison. This information will further assist in providing evidence-based guidance to improve prevention, control and management strategies of IPIs co-infections among both HIV positive and HIV negative inmates in a prison environment.

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.

Strongyloides stercoralis: Global Distribution and Risk Factors

BACKGROUND

The soil-transmitted threadworm, Strongyloides stercoralis, is one of the most neglected among the so-called neglected tropical diseases (NTDs). We reviewed studies of the last 20 years on S. stercoralis's global prevalence in general populations and risk groups.

METHODS/PRINCIPAL FINDINGS

A literature search was performed in PubMed for articles published between January 1989 and October 2011. Articles presenting information on infection prevalence were included. A Bayesian meta-analysis was carried out to obtain country-specific prevalence estimates and to compare disease odds ratios in different risk groups taking into account the sensitivities of the diagnostic methods applied. A total of 354 studies from 78 countries were included for the prevalence calculations, 194 (62.4%) were community-based studies, 121 (34.2%) were hospital-based studies and 39 (11.0%) were studies on refugees and immigrants. World maps with country data are provided. In numerous African, Asian and South-American resource-poor countries, information on S. stercoralis is lacking. The meta-analysis showed an association between HIV-infection/alcoholism and S. stercoralis infection (OR: 2.17 BCI: 1.18-4.01; OR: 6.69; BCI: 1.47-33.8), respectively.

CONCLUSIONS

Our findings show high infection prevalence rates in the general population in selected countries and geographical regions. S. stercoralis infection is prominent in several risk groups. Adequate information on the prevalence is still lacking from many countries. However, current information underscore that S. stercoralis must not be neglected. Further assessments in socio-economic and ecological settings are needed and integration into global helminth control is warranted.

Opportunistic parasites among immunosuppressed children in Minia District, Egypt

A total of 450 stool samples were collected from inpatient and outpatient clinics of Pediatric Department, Minia University Hospital, Minia District, Egypt. Two groups of patients were studied, including 200 immunosuppressed and 250 immunocompetent children. Stool samples were subjected to wet saline and iodine mounts. A concentration technique (formol-ether sedimentation method) was carried out for stool samples diagnosed negative by wet saline and iodine mounts. Samples were stained by 2 different methods; acid fast stain (modified Ziehl-Neelsen stain) and Giemsa stain. Total 188 cases (94%) were diagnosed positive for parasitic infections among immunosuppressed children, whereas 150 cases (60%) were positive in immunocompetent children (P<0.0001). The most common protozoan infection in immunosuppressed group was Cryptosporidium parvum (60.2%), followed by Blastocystis hominis (12.1%), Isospora belli (9.7%), and Cyclospora caytenensis (7.8%). On the other hand, Entamoeba histolytica (24.6%) and Giardia lamblia (17.6%) were more common than other protozoans in immunocompetent children.

Parasitic infections in HIV infected individuals: diagnostic & therapeutic challenges

After 30 years of the human immunodeficiency virus (HIV) epidemic, parasites have been one of the most common opportunistic infections (OIs) and one of the most frequent causes of morbidity and mortality associated with HIV-infected patients. Due to severe immunosuppression, enteric parasitic pathogens in general are emerging and are OIs capable of causing diarrhoeal disease associated with HIV. Of these, Cryptosporidium parvum and Isospora belli are the two most common intestinal protozoan parasites and pose a public health problem in acquired immunodeficiency syndrome (AIDS) patients. These are the only two enteric protozoan parasites that remain in the case definition of AIDS till today. Leishmaniasis, strongyloidiasis and toxoplasmosis are the three main opportunistic causes of systemic involvements reported in HIV-infected patients. Of these, toxoplasmosis is the most important parasitic infection associated with the central nervous system. Due to its complexity in nature, toxoplasmosis is the only parasitic disease capable of not only causing focal but also disseminated forms and it has been included in AIDS-defining illnesses (ADI) ever since. With the introduction of highly active anti-retroviral therapy (HAART), cryptosporidiosis, leishmaniasis, schistosomiasis, strongyloidiasis, and toxoplasmosis are among parasitic diseases reported in association with immune reconstitution inflammatory syndrome (IRIS). This review addresses various aspects of parasitic infections in term of clinical, diagnostic and therapeutic challenges associated with HIV-infection.

Fulminant amebic colitis in an HIV-infected homosexual man

We present a case of fulminant amebic colitis in a human immunodeficiency virus (HIV)-infected homosexual man. The patient developed colonic perforation over a short time despite empirical therapy with metronidazole, and underwent right hemicolectomy. Amebic colitis was pathologically diagnosed by identifying invasive trophozoites of Entamoeba in a surgical specimen. Amebic colitis is one of the important differential diagnoses of acute abdomen in HIV-infected patients and/or homosexual men, especially in East Asia. Although fulminant amebic colitis is a rare manifestation of amebiasis, early diagnosis and treatment are thought to be important to improve the outcome of this highly fatal complication.

Geohelminth Infections among pregnant women in rural western Kenya; a cross-sectional study

Background

Geohelminth infections are common in rural western Kenya, but risk factors and effects among pregnant women are not clear.

Methodology

During a community-based cross-sectional survey, pregnant women were interviewed and asked to provide a blood sample and a single fecal sample. Hemoglobin was measured and a blood slide examined for malaria. Geohelminth infections were identified using the concentration and Kato-Katz method.

Results

Among 390 participants who provided a stool sample, 76.2% were infected with at least one geohelminth: 52.3% with Ascaris lumbricoides, 39.5% with hookworm, and 29.0% with Trichuris trichiura. Infection with at least one geohelminth species was associated with the use of an unprotected water source (adjusted odds ratio [AOR] 1.8, 95% confidence interval [CI] 1.1–3.0) and the lack of treatment of drinking water (AOR 1.8, 95% CI 1.1–3.1). Geohelminth infections were not associated with clinical symptoms, or low body mass index. A hookworm infection was associated with a lower mid upper arm circumference (adjusted mean decrease 0.7 cm, 95% CI 0.3–1.2 cm). Hookworm infections with an egg count ≥1000/gram feces (11 women) were associated with lower hemoglobin (adjusted mean decrease 1.5 g/dl, 95% CI 0.3–2.7). Among gravidae 2 and 3, women with A. lumbricoides were less likely to have malaria parasitemia (OR 0.4, 95% CI 0.2–0.8) compared to women without A. lumbricoides, unlike other gravidity groups.

Conclusion

Geohelminth infections are common in this pregnant population; however, there were few observed detrimental effects. Routine provision of antihelminth treatment during an antenatal clinic visit is recommended, but in this area an evaluation of the impact on pregnancy, malaria, and birth outcome is useful.

In rural western Kenya, both malaria and intestinal infections with worms are common. Pregnant women are particularly vulnerable to infection with malaria, but the effect on pregnancy of intestinal infections with worms is not clear and may depend both on how heavy the worm infection is and on the type of worm. Additionally, it is not clear whether infections with worms may affect malaria infections. In this article, we begin to disentangle some of these issues. Intestinal infections with worms were diagnosed in three-quarters of 390 pregnant women in western Kenya who provided a stool sample. In these women, intestinal worm infections caused a modest decrease both in haemoglobin levels and indicators of nutritional status. Women in their second and third pregnancies who were diagnosed with one particular type of worm infection (Ascaris lumbricoides) were less likely to have malaria than other women in their second or third pregnancies who did not have this type of worm infection. Although our results suggest that it would be good advice to treat women with drugs for intestinal worm infections during their pregnancy in this area, the effect on maternal and infant health and malaria infection needs further study.

[Immigration and HIV Infection. An approximation to parasitic and viral infections]

Highly-active antiretroviral therapy is effective in reducing opportunistic infections in industrialized countries. However, opportunistic parasitic infections remain the leading cause of HIV-related mortality in developing countries. These infections can also affect HIV-positive immigrants residing in Spain, as well as HIV-infected patients traveling to low-income countries. In addition, immigrants often have viral infections caused by herpesvirus, papillomavirus and polyomavirus, which are closely related to risk behaviors and commercial sex. The present article reviews the characteristics of parasitic and viral infections in patients with HIV infection with the aim of improving understanding of this vulnerable population group.

Increased risk for Entamoeba histolytica infection and invasive amebiasis in HIV seropositive men who have sex with men in Taiwan

Background

Incidence of Entamoeba histolytica infection and clinical manifestations and treatment response of invasive amebiasis (IA) in HIV-infected patients have rarely been investigated before.

Methodology/Principal Findings

At the National Taiwan University Hospital, medical records of HIV-infected patients who received a diagnosis of IA between 1994 and 2005 were reviewed. The incidence of amebiasis was investigated in serial blood and stool samples from 670 and 264 HIV-infected patients, respectively, using serological and specific amebic antigen assays. DNA extracted from stool samples containing E. histolytica were analyzed by PCR, sequenced, and compared. Sixty-four (5.8%) of 1,109 HIV-infected patients had 67 episodes of IA, and 89.1% of them were men having sex with men (MSM). The CD4 count at diagnosis of IA was significantly higher than that of the whole cohort (215 cells/µL vs. 96 cells/µL). Forty episodes (59.7%) were liver abscesses, 52 (77.6%) colitis, and 25 (37.3%) both liver abscesses and colitis. Fever resolved after 3.5 days of metronidazole therapy (range, 1–11 days). None of the patients died. The incidence of E. histolytica infection in MSM was higher than that in other risk groups assessed by serological assays (1.99 per 100 person-years [PY] vs. 0 per 100 PY; p<0.0001) and amebic antigen assays (3.16 per 100 PY vs. 0.68 per 100 PY; p = 0.12). In multiple logistic regression analysis, only MSM was significantly associated with acquisition of E. histolytica infection (adjusted odds ratio, 14.809; p = 0.01). Clustering of E. histolytica isolates by sequencing analyses from geographically-unrelated patients suggested person-to-person transmission.

Conclusions/Significance

HIV-infected MSM were at significantly higher risk of amebiasis than patients from other risk groups. Despite immunosuppression, amebic liver abscesses and colitis responded favorably to treatment.

Entamoeba histolytica, morphologically identical to but genetically different from E. dispar and E. moshkovskii, is the causative agent of amebiasis. Recently there have been reports of increased risk for amebiasis among men who have sex with men (MSM) due to oral-anal sexual contact in several developed countries. In this longitudinal follow-up study, the incidence of amebiasis was determined among HIV-infected patients using serological and specific amebic antigen assays. DNA extracted from stool samples containing E. histolytica were analyzed by PCR, sequenced, and compared. Clinical manifestations and treatment response of invasive amebiasis in HIV-infected patients were reviewed. The results demonstrated that HIV-infected MSM were at significantly higher risk of amebiasis than patients from other risk groups. Clustering of E. histolytica isolates by sequencing analyses from geographically unrelated patients suggested person-to-person transmission. Despite immunosuppression, amebic liver abscesses and colitis responded favorably to metronidazole therapy. It is important to investigate in areas of high incidence of both amebiasis and HIV (sub-Saharan Africa) how generalizable these findings are.

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.

Entamoeba histolytica and/or Entamoeba dispar: infection frequency in HIV+/AIDS patients in Mexico city

The objective of this work was to evaluate the frequency of Entamoeba histolytica/Entamoeba dispar intestinal infection in HIV+/AIDS subjects and their HIV- close relatives or sexual partners. Enteric parasites were investigated in stool samples by microscopic examination and E. histolytica and E. dispar were identified by PCR. We found by microscopic analysis in HIV+/AIDS group that the E. histolytica/E. dispar complex was present in 5.9% of the members, while in the HIV- group was 2.9%. With PCR we found that the E. histolytica prevalence was 25.3% in the HIV+/AIDS group and 18.5% in the HIV-group. The difference in the results obtained with the microscopic and PCR is due to the different sensibility of the procedures. Besides, we found patients who were infected with E. histolytica in both groups were asymptomatic cyst passers. Our results suggest that E. histolytica strains prevalent in the studied community appear to be of low pathogenic potential.

Parasitic infection and the polarized Th2 immune response can alter a vaccine-induced immune response

The AIDS epidemic in the Developing World represents a major global crisis. It is imperative that we develop an effective vaccine. Vaccines are economically the most efficient means of controlling viral infections. However, the development of a vaccine against HIV-1 has been a formidable task, and in developing countries chronic parasitic infection adds another level of complexity to AIDS vaccine development. Helminthic and protozoan infections, common in developing countries, can result in a constant state of immune activation that is characterized by a dominant Th2 type of cytokine profile, high IgE levels, and eosinophilia. Such an immune profile may have an adverse impact on the efficacy of vaccines, in particular, an HIV-1 vaccine. Indeed, the CD8 cellular immune response and the corresponding Th1 type cytokines that enhance the CD8 cellular immune response are important for clearing many viral infections. It is believed that an antigen specific CD8 cellular immune response will be an important component of an HIV-1 vaccine.

Overdiagnosis of amoebiasis in the absence of Entamoeba histolytica among patients presenting with diarrhoea in Wonji and Akaki, Ethiopia

To confirm the high reported incidence of intestinal amoebiasis among study participants at 2 cohort sites in Ethiopia where an HIV/AIDS study is taking place, stool samples of 232 patients with complaints of diarrhoea were examined for the presence of Entamoeba histolytica and E. dispar DNA between April and December 2001. By microscopy, 91 (39%) of the study participants were reported to harbour Entamoeba trophozoites and/or four-nucleated cysts. Using specific E. histolytica and E. dispar DNA amplification and detection, none of the study participants were found to be infected with E. histolytica and only 21 (9%) with E. dispar. The consequences of the overdiagnosis of E. histolytica are briefly discussed.

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.

Role of incidental and/or cured intestinal parasitic infections on profile of CD4+ and CD8+ T cell subsets and activation status in HIV-1 infected and uninfected adult Ethiopians

Intestinal parasitic infections have been suggested to cause persistent immune activation leading to an unbalanced immune state. Such a state has been proposed to be a major factor in the pathogenesis of AIDS in an African context. The present study investigated the effect of incidental parasitic infection and treatment on the profile of T cell differentiation and activation markers on CD4+ and CD8+ T cells from HIV-1 infected and uninfected adult Ethiopians. Cryopreserved PBMCs from 64 subjects (41 HIV-negative and 23 HIV-positive) with follow-up visits at 6-monthly intervals were used to compare the effect of incidental intestinal parasites and their treatment upon T cell subset profiles and activation status. The samples were stained with antibodies to various T cell differentiation and activation markers allowing naive, memory, effector, memory/effector, activated and resting CD4+ and CD8+ T cell subsets to be quantified by triple-colour FACScan. Incidental intestinal parasitic infections resulted in a significant increase in memory CD4+ T cell numbers both in HIV-negative and HIV-positive subjects (P < 0.05). There was also a significant increase in the percentage of CD8+ HLA-DR+ T cells (P < 0.05) in HIV-positive subjects co-infected with parasites. In HIV-negative subjects, a significant decline in activated cells and a significant increase in resting CD8+ T cells (P < 0.05) was observed after treatment for parasites. These data suggest that intestinal parasitic infections could result in the alteration of T cell subset counts and also in the up-regulation of T cell activation markers in peripheral blood. Treatment of parasitic infections showed a tendency to reduce the activation suggesting that, together with other community based intervention strategies, such treatment could be used to down-regulate immune activation and hence protect the host from being easily attacked by HIV.

The mouse model of amebic colitis reveals mouse strain susceptibility to infection and exacerbation of disease by CD4+ T cells

Amebic colitis is an important worldwide parasitic disease for which there is not a well-established animal model. In this work we show that intracecal inoculation of Entamoeba histolytica trophozoites led to established infection in 60% of C3H mice, while C57BL/6 or BALB/c mice were resistant, including mice genetically deficient for IL-12, IFN-gamma, or inducible NO synthase. Infection was a chronic and nonhealing cecitis that pathologically mirrored human disease. Characterization of the inflammation by gene chip analysis revealed abundant mast cell activity. Parasite-specific Ab and cellular proliferative responses were robust and marked by IL-4 and IL-13 production. Depletion of CD4(+) cells significantly diminished both parasite burden and inflammation and correlated with decreased IL-4 and IL-13 production and loss of mast cell infiltration. This model reveals important immune factors that influence susceptibility to infection and demonstrates for the first time the pathologic contribution of the host immune response in amebiasis.

Assessing eosinophil count as a marker of immune activation among human immunodeficiency virus-infected persons in sub-Saharan Africa

In 611 human immunodeficiency virus-infected persons who had not yet begun to receive antiretroviral therapy, we evaluated the linear association between absolute eosinophil count (as a surrogate for immune response to helminthic infection) and CD4+ T cell count, and between absolute eosinophil count and log virus load. Overall, no significant correlations were observed between eosinophil count and CD4+ T cell count, or between eosinophil count and log virus load.

Sensitive PCR-restriction fragment length polymorphism assay for detection and genotyping of Giardia duodenalis in human feces

An assay that uses heminested PCR-restriction fragment length polymorphism analysis for the detection and genotyping of Giardia duodenalis on the basis of polymorphism in the triose phosphate isomerase (tpi) gene was developed. This assay was evaluated with DNA extracted from purified parasite material, bacterial cultures, whole human feces containing G. duodenalis and other parasites, and their corresponding immunofluorescence-stained fecal smears on glass microscope slides. The assay was specific and discriminated between G. duodenalis assemblages A and B. RFLP analysis further distinguished two groups (designated groups I and II) within assemblage A. Among 35 DNA samples extracted from whole feces from patients with confirmed sporadic giardiasis, the tpi gene was amplified from 33 (94%). Of these, nine (27%) samples contained assemblage A group II, 21 (64%) contained assemblage B, and 3 (9%) contained a mixture of assemblage A group II and assemblage B. The tpi gene of G. duodenalis assemblage B was amplified from 21 of 24 (88%) DNA samples extracted from whole feces from patients with confirmed cases of infection in a nursery outbreak. No amplification was detected from the remaining three DNA samples. Overall, analysis of DNA extracted from material recovered from stained microscope slides identified identical G. duodenalis genotypes in 35 (65%) of the 54 samples for which a genotype was established with DNA from whole feces. The heminested PCR method developed is sensitive, simple, and rapid to perform and is applicable for the analysis of other intestinal pathogens.

Distribution of lymphocyte subsets in healthy human immunodeficiency virus-negative adult Ethiopians from two geographic locales

Immunological values for 562 factory workers from Wonji, Ethiopia, a sugar estate 114 km southeast of the capital city, Addis Ababa, Ethiopia, were compared to values for 218 subjects from Akaki, Ethiopia, a suburb of Addis Ababa, for whom partial data were previously published. The following markers were measured: lymphocytes, T cells, B cells, NK cells, CD4(+) T cells, and CD8(+) T cells. A more in depth comparison was also made between Akaki and Wonji subjects. For this purpose, various differentiation and activation marker (CD45RA, CD27, HLA-DR, and CD38) expressions on CD4(+) and CD8(+) T cells were studied in 60 male, human immunodeficiency virus-negative subjects (30 from each site). Data were also compared with Dutch blood donor control values. The results confirmed that Ethiopians have significantly decreased CD4(+) T-cell counts and highly activated immune status, independent of the geographic locale studied. They also showed that male subjects from Akaki have significantly higher CD8(+) T-cell counts, resulting in a proportional increase in each of the CD8(+) T-cell compartments studied: naïve (CD45RA(+)CD27(+)), memory (CD45RA(-)CD27(+)), cytotoxic effector (CD45RA(+)CD27(-)), memory/effector (CD45RA(-)CD27(-)), activated (HLA-DR(+)CD38(+)), and resting (HLA-DR(-)CD38(-)). No expansion of a specific functional subset was observed. Endemic infection or higher immune activation is thus not a likely cause of the higher CD8 counts in the Akaki subjects. The data confirm and extend earlier observations and suggest that, although most lymphocyte subsets are comparable between the two geographical locales, there are also differences. Thus, care should be taken in extrapolating immunological reference values from one population group to another.

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.