Human coccidiosis--a possible cause of malabsorption

Intestinal Parasitic Infections in 2023

Intestinal parasites include intestinal protozoa and intestinal helminths. Intestinal parasitic infections (IPIs) pose a global health problem affecting over one billion people worldwide. Although these infections are predominantly seen in the developing world, they are frequently seen in the developed countries, particularly in immunocompromised patients. Patients' clinical presentations generally include diarrhea, dysentery, abdominal pain, nausea, vomiting, nutritional deficiency, iron deficiency anemia, anal and perianal itching, and rarely intestinal obstruction. The intestinal parasites have similarities in their mode of transmission and life cycle. The stool test is the primary way of diagnosing IPIs. Treatment is given with various anti-parasitic agents. However, appropriate preventive measures are essential for successfully controlling the IPIs.

Pitfalls in Morphologic Diagnosis of Pathogens: Lessons Learned From the Pseudo-Cystoisospora Epidemic

Multiple groups have recently reported involvement of the gallbladder mucosa of immunocompetent patients by cystoisospora organisms. However, this has recently been disproved with the support of molecular and ultrastructural studies. Here we present a summary of these events, recounting how this pseudo-Cystoisospora epidemic began and ended. This review also highlights the important role played by ancillary techniques in supplementing the morphologic diagnosis of pathogens.

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.

Endogenous development of Cystoisospora belli in intestinal and biliary epithelium of humans

Cystoisospora(Isospora)belliis a coccidian parasite of humans. It can cause serious digestive disorders involving infection of intestines, biliary tract and gallbladder, especially in those with depressed immunity. It has a direct fecal–oral transmission cycle. After ingestion of sporulated oocysts, the parasite multiplies asexually and sexually within host epithelial cells, resulting in unsporulated oocysts that are excreted in feces. The details of asexual and sexual stages are not known and certain inclusions in epithelial cells in biopsy samples have been erroneously identified recently asC. belli. Here, we provide details of developmental stages ofC. belliin two patients, in duodenal biopsy of one and biliary epithelium of the other. Immature and mature asexual stages (schizonts/meronts) were seen in epithelial cells. The merozoites were seen singly, in pairs and in groups in single parasitophorous vacuole (pv) in host cytoplasm. Immature and mature meronts were seen together in the same pv; up to eight nuclei were seen in meronts that retained elongated crescent shape; round multinucleated schizonts, seen in other coccidians, were not found. Meronts were up to 25µm long and contained up to ten merozoites that were 8–11µm long. The merozoites and meronts contained PAS-positive granules. Microgamonts (male) contained up to 30 nuclei that were arranged at the periphery and had condensed chromatin; 1–3 PAS-positive, eosinophilic, residual bodies were left when microgametes were formed. The microgametes were 4µm long and PAS-negative. All stages of macrogamonts, including oocysts were PAS-positive. The detailed description of the life cycle stages ofC. bellireported here should facilitate in histopathologic diagnosis of this parasite.

Workshop no. 2. Parasitic infection and host nutrition

Even if we do not always acknowledge the fact, nutrition is a fundamental aspect of symbiosis and parasitism. (1) The significance of nutrition often forms a basic feature in schemos of classification of the various associations between living organisms (see Read, 1908; Whitfield, 1979). (2) The growth and reproduction of different parasites appear to Vary in response to the nutrition of the host (see Mettrick & Podesta, 1974; Nesheim, Crompton, Arnold & Barnard, 1977; 1978; Parshad, Crompton & Nesheim, 1980). (3) The course of a parasitic infection may also vary in response to the nutritional status of the host and perhaps such variations are the result of the affocts of nutrition on the host's immune response (Chandra & Nowberne, 1977; Chandra, 1980). (4) Finally, parasitic disease is well known to be much more scrious in undernourished hosts (see Chandra & Newberne, 1977); when man's the deprived host, the impact of infections and parasitic disease on young children is Particularly severe and distressing (Latliam, 1975).

Successful therapeutic management of canine Isosporosis in puppies

Four labrador male puppies were confirmed for the Isospora spp infection by direct smear and flotation method following complains of anorexia, haematemesis and haematochezia. The puppies were treated with trimethoprime and sulphamethoxazole @ 40 mg/kg body weight in combination with metronidazole @ 10 mg/kg body weight twice daily for 5 days which was supported with fluid therapy, aniemetics and plasma expanders. All the animals showed completed clinical recovery along with clearing of faecal oocyst.

Eosinophilia in Infectious Diseases

In determining the etiology of eosinophilia, it is necessary to consider the type of patient, including previous travel and exposure history, comorbidities, and symptoms. In this review, we discuss the approach to the patient with eosinophilia from an infectious diseases perspective based on symptom complexes.

Isospora belli associated recurrent diarrhea in a child with AIDS

Persistent diarrhea is a major manifestation of Acquired Immunodeficiency Syndrome (AIDS) which might be more complicated in Human Immunodeficiency Virus (HIV) infected children especially those from developing countries. There are numerous reports showing the emergence of intestinal opportunistic coccidian parasites, mostly Cryptosporidium parvum and Isospora belli in HIV-infected individuals. The prevalence of isosporiasis is probably underestimated in developing countries because routinely not all HIV-infected patients are examined for the presence of this protozoan infection. Here we report a case of HIV-infected isosporiasis presenting with failure to thrive and persistent diarrhea. Since I. belli infection in children responds well to therapy with trimethoprim-sulfamethoxazole, isosporiasis should be considered as a treatable infection in AIDS, if it is detected at proper time.

Absence of an Association Between Enteric Parasites in the Manifestations and Pathogenesis of HIV Enteropathy in Gay Men

49 gay men confirmed to be infected with the human immunodeficiency virus (HIV) and 9 HIV seronegative gay men participated in a pilot study comparing clinical status and enteric parasite load with gastrointestinal structure, function and symptomatology. Cases included 16/49 (33%) men who were CDC stage II, 7/49 (14%) who were CDC stage III, and 26/49 (53%) who were CDC stage IV. The mean CD4-lymphocyte count was 476 +/- 199 (SD)/microliter. The prevalence of enteric parasitic flora was similar in HIV seropositive patients and controls. Seven cases had enteric infection with pathogenic agents including 3 patients with Entamoeba histolytica, and 4 patients with Giardia lamblia, one of whom also had cryptosporidiosis. Other cases were most frequently colonized with Blastocystis hominis (44%) and Endolimax nana (41%) regardless of the HIV clinical status. HIV seropositive patients with enteric parasitic colonization tended to have lower mean levels of serum IgA than cases without parasites. Duodenal morphometric mucosal changes demonstrated a significant decrease in the mean villous height (p < 0.01) with no elongation of the crypt depth in HIV-infected patients with and without diarrhea compared to controls. Despite gastrointestinal symptoms including diarrhea and weight loss being more prevalent in HIV infected individuals than controls, no correlations were found between the presence of particular enteric parasites, gastrointestinal symptomatology, the clinical HIV status of the CD4-lymphocyte count, the malabsorption of D-xylose or morphometric changes in the duodenum.(ABSTRACT TRUNCATED AT 250 WORDS)

Parasites in patients with malabsorption syndrome: a clinical study in children and adults

BACKGROUND

Intestinal parasites not only cause diarrheal diseases but also significant malabsorption. Literature on the role of parasites, such as intestinal coccidia and microsporidia in malabsorption syndrome is limited.

METHODS

Three consecutive stool samples from 50 adult and 50 children patients with malabsorption syndrome and an equal number of healthy controls without diarrhea were examined for intestinal coccidia, microsporidia and other intestinal parasites by wet mount, Kinyoun's modified acid-fast staining and chromotrope 2R staining.

RESULTS

Celiac disease was the commonest cause of malabsorption syndrome in both adults (52%) and children (74%). Forty (80%) and 41 (82%) adults and children, respectively, with malabsorption syndrome were infected with parasites. These results were significantly higher in comparison to those from the healthy adults and children controls (22% and 16%), respectively (P < 0.001). Of them, 48% and 46% of the adults and children, respectively, with malabsorption had pathogenic parasitic infections. The pathogenic parasites detected in adults were Giardia lamblia 12 (24%), E. histolytica / dispar 5 (10%), Ancylostoma duodenale 4 (8%), H. nana 2 (4%) and Cyclospora cayetanensis 1 (2%). The pathogenic parasites detected in children with malabsorption syndrome were Giardia lamblia 8 (16%), Cryptosporidium 7 (14%), E. histolytica / dispar 3 (6%), Ancylostoma duodenale 3 (6%), Isospora belli 1 (2%), and H. nana 1 (2%). None of the stool samples from healthy controls were positive for Cryptosporidium spp., Cyclospora and Isospora belli. All the patients infected with intestinal coccidia were HIV sero-negative.

CONCLUSION

Celiac disease is the most common cause of malabsorption syndrome in both adults and children. These people harbor significantly more pathogenic parasites and are more frequently colonized with harmless commensals as compared to healthy controls. Intestinal coccidia are associated with malabsorption syndrome, particularly in malnourished children.

Evaluation and differential diagnosis of marked, persistent eosinophilia

Hypereosinophilic syndromes (HES) are a group of heterogeneous disorders many of which remain ill-defined. By definition, the HES must be distinguished from other disorders with persistently elevated eosinophilia with a defined cause. Although marked eosinophilia worldwide is most commonly caused by helminth (worm) infections, the diagnostic approach must include noninfectious (nonparasitic) causes of marked eosinophilia as well.

Tropical malabsorption

Malabsorption is an important clinical problem both in visitors to the tropics and in native residents of tropical countries. Infections of the small intestine are the most important cause of tropical malabsorption. Protozoal infections cause malabsorption in immunocompetent hosts, but do so more commonly in the setting of immune deficiency. Helminth infections occasionally cause malabsorption or protein-losing enteropathy. Intestinal tuberculosis, chronic pancreatitis and small-bowel bacterial overgrowth are important causes of tropical malabsorption. In recent years, inflammatory bowel disease and coeliac disease have become major causes of malabsorption in the tropics. Sporadic tropical sprue is still an important cause of malabsorption in adults and in children in South Asia. Investigations to exclude specific infective, immunological or inflammatory causes are important before considering tropical sprue as a diagnosis. This article briefly reviews the management of tropical sprue and presents an algorithm for its investigation and management.

The diagnostic accuracy of serologic tests for celiac disease: a systematic review

Clinicians are increasingly utilizing noninvasive serologic tests for the diagnosis and screening of celiac disease (CD). The aim of this study was to conduct a systematic review of the diagnostic performance of serologic tests for the diagnosis and screening of CD. Standard systematic review methodology was used. A literature search was conducted in MEDLINE (1966 to October 2003) and EMBASE (1974 to December 2003) databases. A weighted mean of the sensitivity and specificity along with 95% confidence intervals and summary receiver operating characteristic (ROC) curves were calculated. The pooled specificity of endomyseal antibody (EMA)-monkey esophagus (ME) or EMA-human umbilical cord (HU) was close to 100% in adults and children. The pooled specificity of transglutaminase antibody (tTG)-guinea pig (GP) and tTG-human recombinant (HR) were between 95% and 99%. IgA-EMA-ME demonstrated sensitivities of 96% and 97% in children and adults, respectively. EMA-HU demonstrated a similar sensitivity of 97% in children but 90% in adults. The pooled sensitivity of tTG-GP in adults and children was 90% and 93%, respectively. The sensitivity of tTG-HR was 98% and 96%, respectively. The performance of antigliadin antibody was inferior to that of EMA and tTG. EMA and tTG offer high sensitivity and specificity. The sensitivity of these tests appears to be lower than reported when milder histologic grades are used to define CD (below 90%). If true, the nearly perfect negative predictive value of these tests would drop. The positive predictive value of these tests is likely lower than reported when the tests are applied in low-prevalence populations.

Isospora belli Infection: Observation of Unicellular Cysts in Mesenteric Lymphoid Tissues of a Brazilian Patient with AIDS and Animal Inoculation

We describe the finding of unizoic cysts of Isospora belli in lymphoid tissues of a Brazilian patient with AIDS, and discuss the possibilities of their drug resistance, they being the cause of relapses, and of being an indication for the existence of intermediary or paratenic animal hosts.

Food and water safety for persons infected with human immunodeficiency virus

Public health and food safety experts estimate that millions of episodes of illnesses annually can be traced to contaminated food and water. Food and water safety is extremely important to persons infected with the human immunodeficiency virus (HIV) or with acquired immunodeficiency syndrome (AIDS). A compromised immune system causes people with HIV or AIDS to be more susceptible to foodborne illness from eating foods that are unsafely handled and poorly prepared and from using water from unsafe sources. Food- and waterborne illnesses can cause diarrhea, nausea, and vomiting that can lead to weight loss. These illnesses can be minimized or prevented if proper precautions are taken.

Light microscopic and electron microscopic diagnosis of gastrointestinal opportunistic infections in HIV-positive patients

The surgical pathologist is expected to recognise gastrointestinal opportunistic infections in biopsies from HIV-positive patients, and patients immunocompromised iatrogenically by cancer therapy, steroid treatment and transplantation immunosuppression regimes. This review article presents the diagnostic features in gastrointestinal biopsies of microsporidia, cyclospora, isospora, cryptosporidia, mycobacteria, adenovirus, enteropathogenic bacteria, cryptococcus and leishmania. All of these infections have been diagnosed at our hospital in Sydney, Australia, since the AIDS epidemic began. A protocol for the examination and assessment of these gastrointestinal biopsies is presented and discussed.

Isosporosis and unizoite tissue cysts in patients with acquired immunodeficiency syndrome

Isospora belli, a coccidian parasite in humans, has been described as causing chronic diarrhea and acalculous cholecystitis in patients with the acquired immunodeficiency syndrome (AIDS). Diagnosis can be made at the tissue level in the epithelium of the small bowel and by fecal examination. Disseminated extraintestinal forms are uncommon. We studied 118 adult patients with AIDS and chronic diarrhea using stool analysis and endoscopy with duodenal biopsy specimen collection. These samples were processed by routine histology and transmission electron microscopy. Isosporosis was diagnosed in 8 cases. In 2 of them, unizoite tissue cysts were present in the lamina propria, with negative results in stool materials. The cysts were located within a large parasitophorous vacuole. There were no structural means of differentiating the species level of Isospora based on morphology using light or electron microscopy. We believe further work should be done to determine if unizoite tissue cysts are part of the cycle of I belli or of other species of Isospora that could be pathogenic in immunocompromised hosts.

Eosinophilia in the returning traveler

Eosinophilia is one of the most common laboratory abnormalities seen in the returning traveler. Although elevations in peripheral eosinophil levels can occur in a wide variety of disease processes, worldwide, helminth parasites are the major group of infectious agents responsible for eosinophilia. While often directed at helminth infections in their early stages of clinical evolution, the approach to the evaluation of the returning traveler with eosinophilia must consider the many causes of eosinophilia including those not casually related to travel. This article reviews the major parasitic causes of eosinophilia and provides a systematic approach to the evaluation of eosinophilia following travel.

Gastrointestinal pathology in HIV-infected patients

Specific pathologic processes, particularly oral, esophageal, and intestinal infections, are common in the alimentary tract of AIDS patients. Many of these diseases are adequately assessed only by biopsy with histologic examination. Most are rare or unreported in immunocompetent hosts and are easily missed by those not familiar with them. This article describes the gross or endoscopic and histologic appearances and the diagnostic criteria for enteric pathologic processes seen in HIV-infected individuals.

Parasites and Diarrhea. I: Protozoans and Diarrhea

Intestinal parasitism is extremely common, with approximately 70% of all people harboring one or more intestinal parasite. Parasitism and diarrhea are both hyperendemic in areas where sanitation is suboptimal. Many clinicians assume that the identification of intestinal parasites in patients with diarrhea implies that the parasites are the cause. This approach is frequently misguided. Some intestinal parasites such as Giardia lamblia and Entamoeba histolytica certainly do cause diarrhea. Others, for example Entamoeba coli and Ascaris lumbricoides, almost certainly do not. In addition, there are a number of other organisms that have been associated with diarrheal illness in some cases, which may or may not be important pathogens. In this article, we will review the role of protozoans as definite and possible causes of diarrhea. In Part II, we review the role of helminths in diarrhea.

Biology of Isospora spp. from humans, nonhuman primates, and domestic animals

Coccidial parasites of the genus Isospora cause intestinal disease in several mammalian host species. These protozoal parasites have asexual and sexual stages within intestinal cells of their hosts and produce an environmentally resistant cyst stage, the oocyst. Infections are acquired by the ingestion of infective (sporulated) oocysts in contaminated food or water. Some species of mammalian Isospora have evolved the ability to use paratenic (transport) hosts. In these cases, infections can be acquired by ingestion of an infected paratenic host. Human intestinal isosporiasis is caused by Isospora belli. Symptoms of I. belli infection in immunocompetent patients include diarrhea, steatorrhea, headache, fever, malaise, abdominal pain, vomiting, dehydration, and weight loss, blood is not usually present in the feces. The disease is often chronic, with parasites present in the feces or biopsy specimens for several months to years. Recurrences are common, Symptoms are more severe in AIDS patients, with the diarrhea being more watery. Extraintestinal stages of I. belli have been observed in AIDS patients but not immunocompetent patients. Treatment of I. belli infection with trimethoprim-sulfamethoxazole usually results in a rapid clinical response. Maintenance treatment with trimethoprim-sulfamethoxazole is needed because relapses often occur once treatment is stopped.

Persistent diarrhea caused by Isospora belli: therapeutic response to pyrimethamine and sulfadiazine

A 54-year-old human immunodeficiency virus (HIV)-positive homosexual man developed overwhelming watery diarrhea and marked weight loss over a 3-week period. Although Entamoeba histolytica and other nonpathogenic enteric protozoa were observed along with Isospora belli in this patient's stool specimens, they were promptly eradicated after metronidazole (flagyl) treatment. The presence of I. belli oocysts in various stages of development in the stool and clinical symptoms related to Isospora infection persisted for 10 more months despite treatment with combined chemotherapeutic agents. Clinical and parasitiological resolution was ultimately achieved through an 8-week course of pyrimethamine and sulfadiazine.

Role of stool screening tests in diagnosis of inflammatory bacterial enteritis and in selection of specimens likely to yield invasive enteric pathogens

The Leuko-Test yielded a negative predictive value of 98.4% when it was used to screen 325 patients for inflammatory bacterial enteritis and a negative predictive value of 99.4% when it was used to screen 416 stool specimens for those from which enteric pathogens would likely be recovered when cultured. Neither microscopy for fecal leukocytes nor an assay for fecal occult blood, alone or in combination, allowed for the reliable detection of invasive bacterial enteritis or the reliable selection of specimens for culture. When positive in the Leuko-Test, specimens collected from patients after the third day of hospitalization did not yield enteric pathogens when the specimens were cultured, and specimens collected from inpatients within the first 3 days of hospitalization or from outpatients did not contain Clostridium difficile toxin A. As a screening test, the Leuko-Test has the ability to generate rapidly a result which can support the presumptive diagnosis of inflammatory bacterial enteritis or which can be used to determine the suitability of stool specimens for bacteriologic culture.

The relevance of laboratory diagnosis of human cryptosporidiosis and other coccidia

Human infection by Cryptosporidium spp and other coccidia are due to opportunist non-host specific microorganisms. In HIV seropositive patients, the gastrointestinal symptoms accompanying such infections may be serious and prolonged and may include nausea, low-grade fever, abdominal cramps, anorexia and watery diarrhoea. We studied 188 stool samples from 111 patients (84 men and 27 women) with diarrhoea. A modified Ziehl-Nielsen technique for the detection of Cryptosporidium spp and Isospora belli was employed. The mean age of the patients was 31 years. Cryptosporidium spp was seen in 18% (n = 20) of the patients, 90% (n = 18) of whom were HIV seropositive. Isospora belli was recorded only from HIV seropositive patients (5.4% of all the patients studied and 6.5% of those who were HIV seropositive). These data confirm the good results obtained with this technique for the identification of Cryptosporidium spp and other coccidia and also reaffirm the clinical importance of correctly diagnosing the cause of diarrhoea, particularly in HIV seropositive patients.

Submicroscopic profile of Isospora belli enteritis in a patient with acquired immune deficiency syndrome

Small bowel mucosal fragments from a human immunodeficiency virus-positive female patient with chronic diarrhea were investigated by transmission electron microscopy, and Isospora belli enteritis was documented. The submicroscopic profile was characterized by a moderate abnormality of mucosal architecture with reduction in height of villi and hypertrophy of crypts. Stages of both asexual (trophozoite, schizont and merozoite) and sexual (macrogametocyte) phases of the life cycle of the parasite were identified in the epithelium, always enclosed within a parasitophorous vacuole. Moreover, the presence of occasional extracellular merozoites in the intestinal lumen and in the lamina propria near or within lymphatic vessels was documented. These findings expand the current knowledge of this parasite regarding its capacity to survive in an extracellular environment and document a possible mechanism by which extraintestinal infection can take place.

Pathways to the impairment of human nutritional status by gastrointestinal pathogens

Gastrointestinal pathogens are of three varieties, those that can, and often do, take the life of the host, those that infect transiently and rarely are life-threatening, and those (parasites) that establish a relatively prolonged residence or colonization of the host's alimentary tract. In the case of the second form, if infections are recurrent, both catabolic effects during the episode and failure to digest foods and/or absorb nutrients results. Similarly, catabolic wastage through activation of the acute phase response, and interference with the host's acquisition of nutrients by maldigestion, malabsorption, intestinal losses and competition with the parasite burden can impair growth and nutrition with helminthic infections. Growth and nutrition with respect to all of the macronutrients and virtually all of the micronutrients have been documented to be adversely affected by gastrointestinal pathogens. For its burgeoning importance as a worldwide health problem, both with the HIV virus as a direct intestinal pathogen and with the opportunistic gut infections occurring in the immunocompromised host, AIDS represents the emerging context of the impairment of nutritional status by intestinal pathogens.

Eosinophilia in travelers

Eosinophilia in travelers may be caused by infections acquired during travels. Infections with helminthic, but not protozoan, parasites are the most likely causes of eosinophilia, although other etiologies may warrant consideration. This article reviews the parasitic and other causes of eosinophilia. Helminthic infections early in their development may elicit the most pronounced eosinophilia yet be difficult to diagnose. Chronic helminthic infections may yield eosinophilia that persists for prolonged periods of time after initial infection.

Coccidian infections in AIDS. Toxoplasmosis, cryptosporidiosis, and isosporiasis

Cryptosporidium sp. and Isospora belli are coccidian protozoan parasites that were long recognized as pathogens for many animal species. The medical community became acquainted with these organisms with the advent of AIDS. Both parasites are associated with persistent, debilitating enteritis and, in the case of Cryptosporidium, biliary tract involvement in patients with AIDS. For the immunocompetent host, infection with these two pathogens usually results in self-limited diarrhea. Cryptosporidiosis appears to occur more often than isosporiasis, but the true prevalence of both infections for various populations of humans is unknown. Clinically, cryptosporidiosis is indistinguishable from isosporiasis. Diagnosis is based on finding the acid-fast (red staining oocyst in stained fecal specimens). There is no known effective therapy for cryptosporidiosis, whereas patients with isosporiasis respond promptly to treatment with trimethoprim-sulfamethoxazole. Patients with AIDS and isosporiasis have a high relapse rate after achieving complete remission and therefore need to be maintained on suppressive therapy. Much more needs to be learned about these two fascinating, "newly recognized" parasites.

Rhoades Lecture. Effect of infection on nutrient requirements

All infections, no matter how mild, decrease nutrient intakes and increase nutrient losses even when subclinical. The losses include decreased intestinal absorption, direct loss of nutrients in the gut, internal diversion for metabolic responses to infection and increased basal metabolic rate when fever is present. In this way, infection influences not only protein and energy status but also that of most other nutrients. The clinical importance of these consequences of infection depends on the prior state of the individual, the nature and duration of the infection, and the diet of the individual during the infection, particularly dietary intake during the convalescent period and whether full recovery takes place before another infection occurs. In industrialized countries particular attention must be paid to the nutrition of hospitalized patients inasmuch as they are frequently debilitated by their primary disease, morbidity, and nutritional status. Morbidity and mortality are increased by nosocomial infections to which the poorly nourished individual is more susceptible.

Isospora belli infection. A report of two cases in patients with AIDS

OBJECTIVE

To present the findings of Isospora belli infection in two patients with the acquired immunodeficiency syndrome (AIDS).

CLINICAL FEATURES

One patient was part Aboriginal, the other an immigrant recently arrived from Peru. Both men were infected with the human immunodeficiency virus (HIV). They presented with watery diarrhoea, one with severe weight loss. Isospora belli oocysts were detected in multiple faecal specimens from both patients. One patient had a concomitant infection with Cryptosporidium sp.

INTERVENTION AND OUTCOME

There was a rapid response to treatment with cotrimoxazole (960 mg, four times a day for 10 days). A complete response was obtained in the patient with concurrent cryptosporidiosis. The diarrhoea recurred after cessation of treatment, necessitating maintenance therapy.

CONCLUSION

Although Isospora belli is an uncommon cause of gastroenteritis in Australia, it is increasingly recognised as a cause of diarrhoea in travellers, immigrants from endemic areas and immunocompromised people. It has also been reported in the Aboriginal community; this article reports the first case of AIDS-related isosporiasis in an Aborigine. It is likely that both patients acquired Isospora belli before they become HIV seropositive.

Opportunistic protozoan infections in human immunodeficiency virus disease: review highlighting diagnostic and therapeutic aspects

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Alimentary tract cytopathology in human immunodeficiency virus infection: a review of experience in Los Angeles

In the past decade, over 100,000 cases of the acquired immunodeficiency syndrome (AIDS) have been reported in the United States. Conservative estimates suggest that 1.5 million people are infected with the human immunodeficiency virus (HIV), the etiologic agent of AIDS. Major metropolitan areas, such as Los Angeles, have experienced a rapid increase in the number of AIDS cases. At the Los Angeles County-University of Southern California Medical Center, we have gained significant insight into the cytologic findings associated with HIV infection. Based on our experience, we herein review the technical and morphologic evaluation of alimentary tract cytology specimens from this patient population.

Diagnosis of intestinal microsporidiosis in patients with AIDS

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Protozoal infections in the acquired immunodeficiency syndrome

Several protozoa have emerged as the major opportunistic infections and cause of death in patients with acquired immunodeficiency syndrome (AIDS). Pneumocystis carinii pneumonia is the leading cause of death in AIDS patients. Electron microscopy (EM) usually shows numerous trophozoites and cysts of Pneumocystis filling up the entire alveolar space, while only cysts are seen under the light microscope. The focal thickening of cyst wall of Pneumocystis, as demonstrated by EM and manifested as a "parentheses" shaped structure with silver stain, serves as a diagnostic marker for Pneumocystis. Freeze-fracture EM has demonstrated the intimate contact between Pneumocystis trophozoites and the type I pneumocytes, which may contribute to the alveolar-capillary block, leading to severe respiratory distress. However, EM is seldom needed for the diagnosis of this infection. Toxoplasma encephalitis, which is an unusual clinical manifestation in cases of toxoplasmosis reported previously, has become a common complication and one of the major causes of death in patients with AIDS. Because subclinical infection by Toxoplasma is common, serologic tests usually offer no definite answers as to whether the infection is acute or chronic, active or past. The small size and its non-specificity in both morphology and tissue affinity make light microscopic diagnosis of toxoplasmosis difficult. Only immunologic staining, such as immunoperoxidase and immunofluorescence, can help to achieve a definite positive identification of the organism. When special antibodies or facility for such staining is not available, EM is the final resort for identifying Toxoplasma by showing the apical complex with the characteristic sausage-shaped rhoptries. Cryptosporidiosis, practically unknown before the AIDS outbreak, has become one of the most common intestinal protozoa in both immunocompromised and immunocompetent patients. The protracted and sometimes fatal course of cryptosporidiosis in immunocompromised patients can be explained by the presence of autoinfective oocysts (thin-walled oocysts), as detected by EM, and by recycling of first-generation schizonts observed experimentally. While diagnosis of cryptosporidiosis can be made by detection of oocysts in stools in most cases, EM is still the last resort for a definitive identification of Cryptosporidium species. While the incidence of isosporiasis is still low, it has been found more frequently in patients with AIDS than in the general population. The parasite, Isospora belli, being a coccidian as is the Cryptosporidium species, is similar to the latter in its life cycle and clinical manifestations.(ABSTRACT TRUNCATED AT 400 WORDS)

Thrombocytopenia and vomiting due to difluoromethylornithine

A 32-year-old Haitian male with acquired immunodeficiency syndrome presented with complications of Isospora belli enteritis. Therapy with the investigational drug difluoromethylornithine was initiated. Severe thrombocytopenia, nausea, and vomiting developed during intravenous drug therapy and recurred upon rechallenge with low-dose oral difluoromethylornithine. Therapy was discontinued because of these severe adverse effects.

Clinical manifestations and therapy of Isospora belli infection in patients with the acquired immunodeficiency syndrome

Isospora belli has recently been recognized as an opportunistic protozoan pathogen in patients with the acquired immunodeficiency syndrome (AIDS). Although I. belli rarely causes diarrhea in patients with AIDS in the United States, we have documented isosporiasis in 15 percent (20 of 131) of such patients in Haiti. The infection was associated with chronic watery diarrhea and weight loss that was clinically indistinguishable from disease caused by the related coccidia cryptosporidium. No demographic or laboratory data distinguished the patients with AIDS and isosporiasis from those with either cryptosporidiosis or other opportunistic infections. Neither I. belli nor cryptosporidium was detected in stool samples from 170 healthy siblings, friends, and spouses of the patients with AIDS. In all patients with isosporiasis, diarrhea stopped within two days of the beginning of treatment with oral trimethoprim-sulfamethoxazole. Recurrent symptomatic isosporiasis developed in 47 percent of the patients, but it also responded promptly to therapy with trimethoprim-sulfamethoxazole. We conclude that isosporiasis is common in Haitian patients with AIDS, and that it responds to therapy with trimethoprim-sulfamethoxazole but is associated with a high rate of recurrence.