Intestinal parasites including Cryptosporidium, Cyclospora, Giardia, and Microsporidia, Entamoeba histolytica, Strongyloides, Schistosomiasis, and Echinococcus: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of intestinal parasites in the pre- and post-transplant period. Intestinal parasites are prevalent in the developing regions of the world. With increasing travel to and from endemic regions, changing immigration patterns, and the expansion of transplant medicine in developing countries, they are increasingly recognized as a source of morbidity and mortality in solid-organ transplant recipients. Parasitic infections may be acquired from the donor allograft, from reactivation, or from de novo acquisition post-transplantation. Gastrointestinal multiplex assays have been developed; some of the panels include testing for Cryptosporidium, Cyclospora, Entamoeba histolytica, and Giardia, and the performance is comparable to conventional methods. A polymerase chain reaction test, not yet widely available, has also been developed to detect Strongyloides in stool samples. New recommendations have been developed to minimize the risk of Strongyloides donor-derived events. Deceased donors with epidemiological risk factors should be screened for Strongyloides and recipients treated if positive as soon as the results are available. New therapeutic agents and studies addressing the optimal treatment regimen for solid-organ transplant recipients are unmet needs.

Quantitative evaluation of the impact of bather density on levels of human-virulent microsporidian spores in recreational water

Microsporidial gastroenteritis, a serious disease of immunocompromised people, can have a waterborne etiology. During summer months, samples of recreational bathing waters were tested weekly for human-virulent microsporidian spores and water quality parameters in association with high and low bather numbers during weekends and weekdays, respectively. Enterocytozoon bieneusi spores were detected in 59% of weekend (n = 27) and 30% of weekday (n = 33) samples, and Encephalitozoon intestinalis spores were concomitant in a single weekend sample; the overall prevalence was 43%. The numbers of bathers, water turbidity levels, prevalences of spore-positive samples, and concentrations of spores were significantly higher for weekend than for weekday samples; P values were <0.001, <0.04, <0.03, and <0.04, respectively. Water turbidity and the concentration of waterborne spores were significantly correlated with bather density, with P values of <0.001 and <0.01, respectively. As all water samples were collected on days deemed acceptable for bathing by fecal bacterial standards, this study reinforces the scientific doubt about the reliability of bacterial indicators in predicting human waterborne pathogens. The study provides evidence that bathing in public waters can result in exposure to potentially viable microsporidian spores and that body contact recreation in potable water can play a role in the epidemiology of microsporidiosis. The study indicates that resuspension of bottom sediments by bathers resulted in elevated turbidity values and implies that the microbial load from both sediments and bathers can act as nonpoint sources for the contamination of recreational waters with Enterocytozoon bieneusi spores. Both these mechanisms can be considered for implementation in predictive models for contamination with microsporidian spores.

Urban feral pigeons (Columba livia) as a source for air- and waterborne contamination with Enterocytozoon bieneusi spores

This study demonstrated that a person with 30 min of occupational or nonoccupational exposure to urban feral pigeons, such as exposure through the cleaning of surfaces contaminated with pigeon excrement, could inhale approximately 3.5 x 10(3) Enterocytozoon bieneusi spores and that 1.3 x 10(3) spores could be inhaled by a nearby person.

Factors contributing to spontaneous Enterocytozoon bieneusi infection in simian immunodeficiency virus-infected macaques

BACKGROUND

A cohort of SIV-infected macaques had been used to investigate the effect of dietary supplement, immune status, SIV/AIDS disease progression and serum micronutrients levels on spontaneous acquisition of Enterocytozoon bieneusi infection in SIV-infected macaques.

METHODS

Twenty-four SIV-infected macaques were randomized into 2 groups. One group received a vitamin/mineral supplementation and a second group received a placebo. Both groups were examined for E. bieneusi infection.

RESULTS

SIV-infected macaques were more prone to acquire E. bieneusi with the progression of SIV/AIDS, and the increased shedding of infectious spores was directly associated with decreased CD4 lymphocyte and increased circulating SIV, in both supplemented and unsupplemented groups of animals. Dietary supplementation, body composition factors and serum micronutrients levels however had no association with the acquisition of E. bieneusi infection in these animals.

CONCLUSIONS

Acquisition of E. bieneusi infection is related to SIV disease progression, CD4 counts and viral load but independent of changes in body composition and serum micronutrient levels.

Spore shedding pattern of Enterocytozoon bieneusi in asymptomatic children

Stool samples from seven human immunodeficiency virus (HIV)-negative and two HIV-positive children with asymptomatic Enterocytozoon bieneusi infections were daily examined to quantify spore shedding using Gram-chromotrope staining under light microscopy. The spore shedding pattern and intensity in these children was variable. Mean spore concentrations in the stool samples from these children ranged from 2.4 x 10(2) to 1.2 x 10(5) spores per gram. Light microscopy could detect spores in stool specimens for 9-33 days, while PCR was able to detect E. bieneusi in stool specimens for 3-40 days longer. This suggests that light microscopy may not detect low levels of spore shedding. Considering that the asymptomatic group are a potential source of infection, detection methods with a higher sensitivity should be used.

Intraocular microsporidiosis due to Encephalitozoon cuniculi in a patient with idiopathic CD4+ T-lymphocytopenia

Encephalitozoon cuniculi was documented to cause disseminated microsporidial infection including an iris tumor and endophthalmitis in an adolescent with idiopathic CD4+ T-lymphocytopenia. The diagnosis was established by microscopic, serologic and molecular methods. E. cuniculi (rabbit strain) was identified from the iris tumor, as well as from urine, conjunctival, corneal, and nasal swabs. Treatment with oral albendazole led to rapid improvement. This case raises the possibility of disseminated microsporidial infection in the context of idiopathic CD4+ T-lymphocytopenia and possibly advanced human immunodeficiency virus (HIV) infection, and above all the possibility of intraocular infection with E. cuniculi in humans.

Interspecies transmission of Enterozytozoon bieneusi supported by observations in laboratory animals and phylogeny

Enterocytozoon bieneusi is emerging as an important cause of chronic diarrhoea in AIDS patients. Its reservoirs and transmission patterns are unknown. In this study, we have examined E. bieneusi sequences from four Rhesus macaques of different origin, which were kept at one animal facility. The sequences were identical in all animals, which suggested that infection had occurred within the facility. Full sequence agreement of E. bieneusi from macaques was found with an E. bieneusi genotype that occurs frequently in humans. To clarify, the relevance of possible inter-species transmission from man to macaque, a phylogenetic analysis was conducted including all sequences of E. bieneusi deposited in GenBank. The hitherto used system of diverse nomenclatures could be reduced to an outlier group and three main lineages, one of which could be further sub-divided into five subgroups. Based in this phylogeny, an association of parasites and host species could be observed for main lineages 2 and 3, as well as for most of the subgroups of main lineage 1. For confirmation, the phylogeny of main lineage 1 was reconstructed with an alternative method of distance estimation, yielding essentially the same parasite-host associations. Zoonotic potential of E. bieneusi is thus supported on a phylogenetic basis.

Disseminated microsporidiosis in a pancreas/kidney transplant recipient

Human microsporidiosis has been described most commonly in patients with acquired immunodeficiency syndrome and only rarely in those with other forms of immunosuppression. Only 11 cases of microsporidiosis have been reported previously in solid transplant recipients. To our knowledge, this is the first report to describe a case of microsporidiosis in a pancreas/kidney transplant recipient in whom multi-organ system dissemination was observed. This infection was not detected until postmortem examination of stained tissue sections revealed microsporidian spores that were identified as Encephalitozoon species by transmission electron microscopy. It is suspected that leakage from the duodenal anastomosis to the bladder may have contributed to the dissemination of this infection.

Pulmonary infection with microsporidia after allogeneic bone marrow transplantation

Microsporidia are obligate, intracellular protozoal parasites that can be pathogenic in immunocompromised individuals. The majority of cases of microsporidiosis have been documented in patients with HIV, and only a few case reports exist of infection in solid organ transplant patients. We report the first case of pulmonary microsporidial infection in an allogeneic bone marrow transplant recipient in the US. The patient was a recipient of a T-cell-depleted graft who succumbed to complications from respiratory failure 63 days post transplant. The diagnosis was made post mortem by electron microscopy and confirmed with PCR. Although rare, microsporidial infection should be considered in the differential diagnosis of unexplained pulmonary infection in bone marrow transplant patients.

Microsporidial keratoconjunctivitis in a healthy patient with a history of LASIK surgery

PURPOSE

To describe a case of microsporidia corneal infection in a HIV-negative patient who did not wear contact lenses.

METHOD

Case report and review of literature.

RESULTS

This is the first case report of a human immunodeficiency virus-negative individual, a non-contact lens wearer, with microsporidia infection.

CONCLUSION

Microsporidia keratoconjunctivitis may occur in healthy subjects with no antecedent contact lens wear.

Phylogenetic relationships of Pleistophora-like microsporidia based on small subunit ribosomal DNA sequences and implications for the source of trachipleistophora hominis infections

The microsporidian Trachipleistophora hominis was isolated in vitro from the skeletal muscle of an AIDS patient. Since its discovery several more cases of myositis due to Trachipleistophora have been diagnosed but the source of infection is unknown. Morphologically, T. hominis most closely resembles Pleistophora and Vavraia, which undergo polysporous sporogony in sporophorous vesicles, but differs from these genera in the mode of formation of sporoblasts and in the morphology of the sporophorous vesicles. Alignment and analyses of the small subunit ribosomal DNA sequences of T. hominis and several other polysporoblastic genera indicated that its closest phylogenetic relationships were with species of the genera Pleistophora and Vavraia, in line with morphological predictions. The type species of the latter two genera are Pleistophora typicalis and Vavraia culicis; these are parasites of fish and mosquitoes, respectively. These results suggest two possible routes and sources of infection to AIDS patients, these being perorally by ingestion of inadequately cooked fish or crustaceans or percutaneously during a bloodmeal taken by a haematophagous insect. Support for an insect source has been provided by recent detection of a microsporidium from mosquitoes in human corneal tissue.

[Disseminated infestation of Enterocytozooon bieneusi a an HIV-infected patient]

An HIV-positive patient developed disseminated Enterocytozoon bieneusi infection. The parasite was identified in stool, duodenal biopsy, nasal discharge, and sputum specimens using transmission electron microscopy. Albendazole therapy failed to improve the symptoms or eradicate the parasite. The patient survived for nine months after the diagnosis of E. bieneusi infection.

Declining CD4+ T-lymphocyte counts are associated with increased risk of enteric parasitosis and chronic diarrhea: results of a 3-year longitudinal study

From January 1991 through September 1994, we observed people who were infected with HIV to assess the impact of enteric parasite-associated diarrhea. Respondents answered comprehensive questionnaires covering clinical and epidemiologic information and provided stool specimens monthly, which were examined unstained as well as stained with trichrome, chromotrope 2R, and with Kinyoun carbol-fuchsin, and with indirect immunofluorescence for Cryptosporidium. In all, 602 participants, who were interviewed, provided stool specimens at 3254 monthly visits. Parasites were associated with 50 of 354 (14.1%) acute diarrheal episodes (lasting < or = 28 days) and with 97 of 279 (34.8%) chronic episodes (lasting > 28 days). A parasite was associated with 31 of 222 (14.0%) episodes that occurred when CD4+ counts were > or = 200 cells/microl and with 150 of 566 (26.5%) episodes that occurred when CD4+ counts were < 200 cells/microl. The most commonly identified parasite was C. parvum, which was associated with 18 of 354 (5.1%) acute episodes and 36 (12.9%) of the 279 chronic episodes of diarrhea. In this patient population, enteric protozoan parasites were commonly associated with illness, particularly as immunosuppression worsened, and were more likely to be associated with chronic rather than acute diarrhea.

Animal models of human microsporidial infections

Two new models have been described for Enterocytozoon bieneusi, non-human primates and immuno-suppressed gnotobiotic pigs, but there still is no successful cell culture system. The intestinal xenograft system holds promise as an animal model for Encephalitozoon intestinalis. Encephalitozoon hellem is easily propagated in mice, and also may be an important cause of spontaneous disease of psittacine birds. Encephalitozoon cuniculi occurs spontaneously in a wide variety of animals and can be induced experimentally in athymic mice. This is a useful experimental system and animal model, but the infection is relatively rare in man. Mammalian microsporidioses first were recognized as spontaneous diseases of animals that later confounded studies intended to elucidate the nature of diseases of humans. Much was learned about both experimental and spontaneous animal microsporidial infections that subsequently has been applied to the human diseases. In addition, new diseases have appeared, in both animals and humans, for which models are being developed. Since there are now animal models for almost all the known human microsporidioses, information on pathogenesis, host defenses, and effective treatments may become available soon. The microsporidioses provide a good example of the value of comparative pathology. Dr. Payne: Joe Payne. How much accidental infection has occurred with adjacent laboratory animals? Dr. Shadduck: A hard question. The organisms are thought to spread horizontally, and there is some pretty good evidence for that in rabbits. One assumes that this also is the explanation for the occurrence in infected kennels. Horizontal transmission probably occurs via contaminated urine, at least in the case of rabbits and dogs. Experimentally, horizontal transmission has been difficult to demonstrate in mice. Relative to the danger in people, I don't know how to answer that. I have always treated this as one of those things where you should be careful, but you shouldn't get paranoid. So, we have handled infected cell cultures and animals as if they were potentially infectious for man, but not as if they were something as hot as the human AIDS virus, for example. With the increasing number of reports in humans, I think it is clear that one would never want anybody who was at risk of being immunocompromised to work with these organisms. Dr. Fenkel: Are there other questions? Dr. Mysore: How do the parasites spread within the infected hosts? Dr. Shadduck: The usual answer is hematogenously via infected macrophages, but data that actually support that statement are rare. One does see infected macrophages in tissues, so it is not unreasonable to think that some of them escape and lodge in other tissues. But that has never actually been formally demonstrated. Dr. Nakeeb: Is E. bieneusi a human pathogen? Dr. Shadduck: The answer depends on which paper you read and what approach the authors took. There are papers in which the authors argue that the organism is not a cause of clinical disease in AIDS patients, but the general belief today is that the parasite does cause diarrhea and enteritis. I think the evidence for pathogenicity is quite strong for the various species of the Encephalitozoon, based on the severity and distribution of the lesions.

Modification of the clinical course of intestinal microsporidiosis in acquired immunodeficiency syndrome patients by immune status and anti-human immunodeficiency virus therapy

The clinical course of 37 Enterocytozoon bieneusi-infected acquired immunodeficiency syndrome patients with diarrhea was studied. Parasite clearance was seen in 15 patients (40.5%). Clearance of E. bieneusi resulted in a 25-100% reduction in episodes of diarrhea, suggesting that microsporidia are true pathogens. Univariate and multivariate proportional hazards analyses revealed that peripheral blood CD4 cell counts > or = 100/mm3, the use of two or more antiretroviral medications, and use of a protease inhibitor were statistically associated with decreased time to clearance of E. bieneusi. Specific anti-microsporidial therapy (albendazole) was not associated with parasite eradication. Factors related to immunocompetence and human immunodeficiency virus suppression appeared to be important in the clearance of E. bieneusi.

Treatment of HIV-1-associated microsporidiosis and cryptosporidiosis with combination antiretroviral therapy

BACKGROUND

Enterocytozoon bieneusi and Cryptosporidium parvum cause chronic antimicrobial-resistant gastrointestinal infections in HIV-1-infected individuals. HIV-1 reverse transcriptase inhibitors delay the onset of opportunistic infections, but are not known to reverse established infections. HIV-1 protease inhibitors are more effective across a broader range of HIV-1-infected immune cells. Combination antiretroviral therapy that includes a protease inhibitor could improve immunity to E bieneusi and C parvum.

METHODS

HIV-1 infected patients with chronic microsporidiosis (five), cryptosporidiosis (three), or dual infection (one), were treated with combination therapy that included at least one HIV-1 protease inhibitor. Outcome measures were symptoms, weight, use of antidiarrhoeal and antimicrobial drugs, T-lymphocyte subsets, HIV-1 viraemia, stool microscopy, and biopsy by endoscopy.

FINDINGS

All patients had complete clinical responses, gained a median 15 kg in weight, and ceased all antidiarrhoeal and antimicrobial therapies. Biliary cryptosporidiosis responded in both affected patients. Neither pathogen was detected in follow-up stool microscopy (eight of eight patients) or in biopsy samples by endoscopy (five of five). Intestinal architecture returned to normal in three patients. There was a dense CD8 lymphocyte and macrophage infiltrate and staining of intraepithelial E bieneusi with interferon-gamma before and after treatment, but little staining for CD4 or B lymphocytes, interleukin 10, or HIV-1 gp41. Five patients remained symptom-free after a median 13 months follow-up. Four patients had recurrent diarrhoea at 7-13 months (one with positive stool microscopy), associated with declining CD4 counts.

INTERPRETATION

Combination antiretroviral therapy that includes a protease inhibitor can restore immunity to E bieneusi or C parvum in HIV-1 infected individuals, and result in complete clinical, microbiological, and histological responses. The persistent CD8 cell and macrophage infiltrate, and the rapid time to relapse in patients with declining CD4 lymphocyte counts, suggest that neither infection was eradicated.

Microsporidial keratoconjunctivitis in a patient without human immunodeficiency virus infection

PURPOSE

To describe a case of microsporidial keratoconjunctivitis in a patient without human immunodeficiency virus (HIV) infection.

METHODS

Case report. An epithelial corneal scraping from a woman with chronic bilateral keratoconjunctivitis was evaluated by Giemsa stain.

RESULTS

Giemsa stain of an epithelial corneal scraping disclosed intracellular and extracellular spores characteristic of microsporidia. An HIV enzyme-linked immunosorbent assay (ELISA) test was negative. The signs and symptoms of the bilateral keratoconjunctivitis resolved after treatment with albendazole.

CONCLUSION

Microsporidia may cause a chronic epithelial keratoconjunctivitis in the absence of HIV infection.

Emerging and reemerging infections. Progress and challenges in the subspecialty of infectious disease pathology

Emerging and reemerging infections are attracting greater attention from the public health and medical communities. Pathologists and other physicians are increasingly aware of the importance of the subspecialty of infectious disease pathology as a tool for diagnosis, surveillance, and research of emerging infections. In this communication, we describe the role that infectious disease pathologists have played during the last 2 years in broadening our understanding of selected emerging infections, including such examples as new variant Creutzfeldt-Jakob disease and bovine spongiform encephalopathy, leptospirosis, microsporidiosis, Ebola hemorrhagic fever, and cyclosporiasis. The significance of providing pathology services, especially the autopsy, to patients with potentially hazardous communicable diseases is discussed with the supposition that it is unethical to exclude or withhold health care from a patient based on his or her underlying disease or on risk factors for acquiring a disease. The increasing occurrence of infectious diseases imported into the United States and other nations, including human immunodeficiency virus-1 group O, dengue fever, tuberculosis, malaria, diphtheria and cholera in immigrants and travelers, and Ebola virus in nonhuman primates, emphasizes the necessity for pathologists of having competence with infectious disease pathology. It is critical that new generations of pathologists not only be trained in the subspecialty of infectious disease pathology, but that they also be willing participants in the diagnosis and investigation of infectious diseases. The lack of training programs for infectious disease pathologists, as well as the deficiency in infectious disease pathology support for ongoing and future epidemiologic investigations and research, has led to the broadening of pathology services and initiation of a dedicated section of Infectious Disease Pathology at one of the nation's premier public health institutions, the Centers for Disease Control and Prevention in Atlanta, Ga. Together with preexisting groups of medical and veterinary infectious disease pathologists at universities, the Armed Forces Institute of Pathology, the US Army Medical Research Institute of Infectious Diseases, and the National Institutes of Health, this new program will significantly strengthen the capability of the United States to respond to future challenges of emerging and reemerging infections, both in this country and abroad.

Opportunistic properties of Nosema algerae (Microspora), a mosquito parasite, in immunocompromised mice

In the last ten years microsporidia have been recognized as opportunistic pathogens in AIDS patients. The sources of infection and the mechanisms of transmission of these organisms in humans are mostly uncertain. Transmission of invertebrate microsporidia to mammals is normally considered impossible, temperature being a limiting factor for development. Mice treated with cortisone acetate and with cyclosporin A, respectively, as well as athymic nice were injected intravenously, intranasally, perorally and subcutaneously with spores of Nosema algerae, a microsporidian species of culicine mosquitoes. No infection could be detected in tissue samples of cortisone acetate and cyclosporin A treated mice. However, the experimental inoculation of spores into the tail and foot of athymic mice caused severe infection in skeletal muscles and the connective tissue. In some tails, nerve tissue and bone marrow were also infected. Vegetative stages and spores were seen in direct contact to host cell cytoplasma. For the first time the prolonged and progressive development of an invertebrate microsporidium in a mammalian host is shown. The possibility of invertebrate microsporidia as a source of human microsporidiosis should now be taken into consideration.

Factors associated with microsporidial and cryptosporidial diarrhea in HIV infected patients

Cryptosporidium and microsporidia are increasingly recognized as important agents of chronic diarrhea in human immunodeficiency virus (HIV) infected patients. These protozoa present clinical and biological similarities but coinfection with these two parasites seems uncommon in a population of diarrheic HIV infected patients in the Paris area (France), a comparison study was performed in order to clarify epidemiological differences between these protozoa. From November 1993 to December 1994, 26 microsporidial infected patients were compared to 28 cryptosporidial patients for various factors. Results of a multivariate logistic regression analysis showed that trips to tropical countries remained strongly associated with microsporidic compared with Cryptosporidium adjusted odds ratio [OR] = 4.6, 95% confidence interval [CI] 1.1-19.5). Thus, as compared with cryptosporidiosis, specific epidemiological factors could be associated with microsporidial transmission in tropical countries.

Intestinal microsporidiosis in Italian individuals with AIDS

A survey on microsporidiosis in individuals with AIDS presenting chronic diarrhoea was carried out in Italy, over a four-year period (1992-1995). Three out of 72 (4.2%) individuals were found positive, on intestinal biopsies, for Enterocytozoon bieneusi by light microscopy and transmission electron microscopy (TEM). Sixteen individuals with AIDS, from a second group of subjects, were confirmed positive, by TEM, for intestinal microsporidiosis due to Enterocytozoon bieneusi. Of these 19 cases, 10 (52.6%) were homosexual men. Two of these individuals, under albendazole treatment, showed also spores with unusual features. The prevalence of intestinal microsporidiosis (12-50%) reported in European countries, Australia and North America, where homosexuality is the major HIV risk factor (63-77%), is higher than in Italy, where homosexual men represent only 16% of the total number of AIDS cases.

Enterocytozoon bieneusi as a cause of chronic diarrhea in a heart-lung transplant recipient who was seronegative for human immunodeficiency virus

Enterocytozoon bieneusi is a major cause of chronic diarrhea and malabsorption in patients with AIDS. We report what we believe is the first case of intestinal infection due to E. bieneusi in a heart-lung transplant recipient who was seronegative for human immunodeficiency virus (HIV). The clinical presentation and the evolution of the disease were identical to those usually observed in patients with AIDS and included diarrhea, massive weight loss, and persistent infection despite treatment with albendazole. E. bieneusi was identified in the patient's duodenal mucosa by electron microscopy. No other etiologic agent was detected. We conclude that E. bieneusi may be responsible for serious intestinal infections in patients whose immunosuppression is not related to HIV.

Microsporidial keratoconjunctivitis caused by Septata intestinalis in a patient with acquired immunodeficiency syndrome

PURPOSE

To examine and treat a patient with acquired immunodeficiency syndrome (AIDS) who had mildly hyperemic conjunctiva and epithelial keratopathy in both eyes.

METHODS

The patient underwent conjunctival biopsy. The specimen was examined by transmission electron microscopy.

RESULTS

Septata intestinalis was demonstrated to be the cause of keratoconjunctivitis in the patient. The keratoconjunctivitis resolved after three weeks of therapy with topical fumagillin. No organisms were seen on repeat conjunctival biopsy.

CONCLUSIONS

Microsporidial keratoconjunctivitis in patients with AIDS can be caused by S. intestinalis. This condition appears to respond to topical fumagillin.

Diarrhoea in HIV-infected patients: no evidence of cytokine-mediated inflammation in jejunal mucosa

OBJECTIVE

To determine whether a mucosal cytokine-mediated inflammatory response is involved in cryptosporidial or microsporidial diarrhoea, as well as in diarrhoea of unknown origin in HIV-infected patients.

DESIGN

Prospective study.

METHODS

Jejunal biopsies were obtained from HIV-infected patients with diarrhoea. Controls were HIV-infected and HIV-seronegative patients without diarrhoea. Two biopsies were homogenized immediately and two other biopsies were first cultured for 20 h. Cytokines [tumour necrosis factor (TNF), interleukin (IL)-1 beta, IL-6, IL-8, IL-10], soluble TNF receptors (sTNFR) p55 and p75, and soluble IL-2 receptor (sIL-2R) were assessed in the homogenates and in the supernatants by sandwich enzyme-linked immunosorbent or enzyme-linked binding assays. The cytokine receptors were also measured in serum.

RESULTS

Six HIV-infected patients with cryptosporidiosis, six with microsporidiosis, seven with diarrhoea of unknown origin, seven without diarrhoea, and seven HIV-seronegative patients were eligible. Four patients were excluded because of the presence of other pathogens. No cytokines were detected in immediately homogenized jejunal tissue. Following culture, IL-6 and IL-8 levels were higher in HIV-infected patients with diarrhoea of unknown origin than in HIV-seronegative controls without diarrhoea, although this was not statistically significant. No differences in serum or post-culture supernatant sTNFR p55 and p75 levels existed between the HIV-infected patients with or without diarrhoea. sTNFR, IL-1 beta, IL-10 and the sIL-2R were only detected in low amounts or not at all, and were equally distributed among all patient groups.

CONCLUSIONS

This study indicates that mucosal cytokine-mediated inflammatory responses do not play an important role in the pathogenesis of different types of diarrhoea in HIV-infected patients. These results do not support the use of immunomodulatory therapy in these patients.