Summary: 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.

https://cmr.asm.org/content/cmr/22/4/634.full.pdf

Clinical Significance of Enteric Protozoa in the Immunosuppressed Human Population

https://www.gastrojournal.org/article/S0016-5085(09)00359-X/pdf

Diagnosis and Treatment of Acute or Persistent Diarrhea

Background & objective Enteric parasites are major cause of diarrhoea in HIV infected individuals. The present study was undertaken to detect enteric parasites in HIV infected patients with diarrhoea at different levels of immunity. Methods The study was carried out at National AIDS Research Institute, Pune, India, between March 2002 and March 2007 among consecutively enrolled 137 HIV infected patients presenting with diarrhoea. Stool samples were collected and examined for enteric parasites by microscopy and special staining methods. CD4 cell counts were estimated using the FACS count system. Results Intestinal parasitic pathogens were detected in 35 per cent patients, and the major pathogens included Cryptosporidium parvum (12%) the most common followed by Isospora belli (8%), Entamoeba histolytica/Enatmoeba dispar (7%), Microsporidia (1%) and Cyclospora (0.7%). In HIV infected patients with CD4 count 200-499 and >or= 500 cells/microl (P=0.001, P=0.016) respectively. Interpretation & conclusion Parasitic infections were detected in 35 per cent HIV infected patients and low CD4 count was significantly associated with opportunistic infection. Detection of aetiologic pathogens might help clinicians decide appropriate management strategies.

Opportunistic parasitic infections in HIV/AIDS patients presenting with diarrhoea by the level of immunesuppression.

It has been known that only 5 to 10% of those infected with Entamoeba histolytica develop symptomatic disease. However, the parasite and the host factors that determine the onset of disease remain undetermined. Molecular typing by using polymorphic genetic loci has been proven to aid in the close examination of the population structure of E. histolytica field isolates in nature. In the present study, we analyzed the genetic polymorphisms of two noncoding loci (locus 1-2 and locus 5-6) and two protein-coding loci (chitinase and serine-rich E. histolytica protein [SREHP]) among 79 isolates obtained from different geographic regions, mainly Japan, Thailand, and Bangladesh. When the genotypes of the four loci were combined for all isolates that we have analyzed so far (overlapping isolates from mass infection events were excluded), a total of 53 different genotypes were observed among 63 isolates. The most remarkable and extensive variations among the four loci was found in the SREHP locus; i.e., 34 different genotypes were observed among 52 isolates. These results demonstrate that E. histolytica has an extremely complex genetic structure independent of geographic location. Our results also show that, despite the proposed transmission of other sexually transmitted diseases, including human immunodeficiency virus infection, from Thailand to Japan, the spectra of the genotypes of the E. histolytica isolates from these two countries are distinct, suggesting that the major E. histolytica strains prevalent in Japan at present were likely introduced from countries other than Thailand. Although the genetic polymorphism of the SREHP locus was previously suggested to be closely associated with the clinical presentation, e.g., colitis or dysentery and liver abscess, no association between the clinical presentation and the SREHP genotype at either the nucleotide or the predicted amino acid level was demonstrated.

Geographic Diversity among Genotypes of Entamoeba histolytica Field Isolates

The clinical course of human immunodeficiency virus (HIV) disease and pattern of opportunistic infections varies from patient to patient and from country to country. The clinical profile of HIV disease in India includes a wide range of conditions like tuberculosis, cryptococcal meningitis, popular pruritic eruptions, and cytomegalovirus retinitis, among others. Tuberculosis is the most common opportunistic infection in Indian patients with HIV. Occurrence of various AIDS-associated illnesses determines disease progression. Mean survival time of Indian patients after diagnosis of HIV is 92 months. In this review, we discuss the clinical profile of HIV disease through an organ system-based approach. With the availability of antiretroviral therapy at lower cost, the clinical profile of HIV disease in India is now changing to include drug-related toxicities and immune reconstitution syndrome.

Clinical profile of HIV in India.

Background. Diarrhoeais a common clinicalmanifestation of HIV infection regardless of whether or not patients have AIDS. Two newly recognizedopportunistic coccidialprotozoa are parasitic pathogens in AIDS patients. We attempted to determine the common parasitesin Indian patients with AIDS. Hethods. BetweenOctober 1994 and December 1996, a total of 110 stool specimensfrom 94 AIDSpatients with acute or chronic diarrhoea were examined by microscopy of wet mounts and smearsstainedby a modifiedZiehl-Neelsen's (cold) stainingmethod. Results. Isosporabelli was the most frequently encountered parasitein 17% of patients, followedby Entamoeba histolyticain 14.9% and Cryptosporidium in 8.5%. Strongyloidesstercoralis and Giardialambliawere detected in 5.3% and 4.3% of patients, respectively. Conclusion. The presence of different parasites in 56.4% of stool specimens of patients with AIDS indicates that their specific diagnosisis essential. This will help initiate therapy to

J K Maniar

Papers

Parasitic diarrhoea in patients with AIDS.