Isospora belli enteric infection in patients with human T-cell leukemia virus type I-associated adult T-cell leukemia

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.

A road less travelled: Clinical comparison of HIV seropositive and seronegative patients with cystoisosporiasis - An 11-year experience from a tertiary care centre in Northern India

Background

Cystoisospora is a well-known opportunistic enteric parasite among human immunodeficiency virus (HIV) seropositive patients but there is a paucity of data among HIV negative patients. This study investigated Cystosporiasis on both HIV positive and negative patients, with or without diarrhea, presenting to a tertiary care and super specialty center of northern India.

Methodology

Oocysts of Cystoisospora were detected on light microscopy, by modified Kinyoun staining of stool specimens, over an 11-year study period.

Results

Of the 10,233 stool specimens evaluated, Cystoisospora was detected in 64 patients, 37 (57.81%) of whom were HIV positive. Year-wise analysis showed an overall declining trend of cystoisosporiasis. Maximum cases were detected in May and June in HIV positive patients and February and September among HIV negative patients. Among HIV positive patients, the mean CD4 count was 152.04 ± 81.12cells/μL, mean absolute eosinophil count (AEC) was 229.16 ± 175.62 cells/μL and 12.5% patients had mild eosinophilia. Tuberculosis was the most common co-morbidity. Dual infections of Cystoisospora with Cryptosporidium and Giardia were also seen. Among HIV negative patients, eight had primary autoimmune disorders, seven were solid organ transplant recipients and the rest had chronic bowel diseases. The mean AEC was 485.47 ± 414.88 cells/μL, with 14.81% patients showing mild and 11.11% showing marked eosinophilia. Dual infection with Giardia was seen. Recurrent cystoisosporiasis was noted, despite cotrimoxazole treatment in a single case.

Conclusion

The epidemiology of cystoisosporiasis differs between HIV seropositive and seronegative patients in terms of year-wise and month-wise trends, co-infections and most importantly, AECs.

Isospora belli Infection with Chronic Diarrhea in an Alcoholic Patient

Chronic diarrhea with a 35 kg weight loss (75 kg to 40 kg) occurred during 2 years in an alcoholic patient was diagnosed with Isospora belli infection in the Republic of Korea. The patient, a 70-year old Korean male, had been a heavy drinker for more than 30 years. He was admitted to the Seoul National University Hospital because of long-standing diarrhea and severe weight loss. He had an increased white blood cell (WBC) count with high peripheral blood eosinophilia (36.8-39.9%) and lowered protein and albumin levels but without any evidence of immunosuppression. A parasitic infection was suspected and fecal examination was repeated 3 times with negative results. Peroral endoscopy with mural biopsy was performed in the upper jejunum. The biopsy specimens revealed villous atrophy with loss of villi together with various life cycle stages of I. belli, including trophozoites, schizonts, merozoites, macrogamonts, and microgamonts. The patient was treated successfully with oral doses of trimethoprim 160-320 mg and sulfamethoxazole 800-1,600 mg daily for 4 weeks. A follow-up evaluation at 2.5 years later revealed marked improvement of body weight (68 kg), increased protein and albumin levels, and normal WBC count with low eosinophils (3.1%). This is the first clinical case of isoporiasis with demonstration of various parasitic stages in the Republic of Korea.

Severe Isospora (Cystoisospora) belli Diarrhea Preceding the Diagnosis of Human T-Cell-Leukemia-Virus-1-Associated T-Cell Lymphoma

Isospora (Cystoisospora) belli diarrhea can sometimes be fulminant in immunocompromised patients. It is endemic in tropical and subtropical areas, and sporadic episodes have been reported in nonendemic areas in nursing homes, day-care centers, and psychiatric institutions. We describe isosporiasis in an HIV-negative Sudanese-American female who presented with a debilitating diarrheal illness and profound weight loss. Isospora belli was detected in her stool by modified acid-fast staining. Serologic testing was negative for HIV but positive for HTLV-1 infection. Treatment with TMP-SMZ led to improvement in her diarrhea which recurred after stopping antibiotics. Subsequently, she developed generalized lymphadenopathy which was diagnosed as ATLL on immunohistochemical staining. Chemotherapy was initiated, but her condition continued to worsen due to persistent diarrhea and resulting profound electrolyte abnormalities. The patient opted for comfort measures and died a few weeks later at a nursing facility. This case emphasizes that the detection of I. belli should trigger testing for HIV, HTLV-1, and other causes of immunocompromise. We suggest that treatment with TMP-SMZ should be initiated and continued for a prolonged period of time in immunocompromised patients with I. belli diarrhea.

Clinical significance of enteric protozoa in the immunosuppressed human population

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

Isospora belli infection in a patient with non-Hodgkin's lymphoma

Isospora belli infection is frequent in patients with acquired immunodeficiency syndrome in tropical areas. It has also been reported in other immunodepressive diseases, such as lymphoblastic leukemia, adult T-cell leukemia, and Hodgkin's disease. To date, no case of non-Hodgkin's lymphoma-related isosporiasis has been reported in a non-HIV-infected patient. We describe a case of non-Hodgkin's lymphoma with chronic diarrhea due to I. belli. In Europe, I. belli can cause severe chronic diarrhea in patients with malignancies whose country of origin is in an endemic area. Trimethoprim-sulfamethoxazole can provide rapid and prolonged clinical and parasitologic cure.

Emerging and reemerging intestinal protozoa

The intestinal protozoa have gained importance to physicians practicing medicine in the United States, Canada, and Europe during recent years as a result of increasing world travel, the globalization of the world's economy, and the growing number of chronically immunosuppressed people. During the spring of 1996, Cyclospora cayetanensis caused diarrhea in approximately 1500 people exposed to Guatemalan raspberries. This epidemic recurred in 1997, emphasizing the risks of the global economy and food supply on which we depend. In addition to importation of intestinal protozoa from the tropics, AIDS and the increasing use of organ transplants have created a new population of people at risk for chronic infection by ubiquitous protozoa previously not known to cause serious human disease. These infections include cryptosporidiosis, isosporiasis, and microsporidiosis. Finally, Entamoeba histolytica, the etiologic agent of invasive amebiasis, has only recently been recognized to be a distinct species from a nonpathogenic but indistinguishable (by light microscopy) intestinal commensal, Entamoeba dispar. The rapidly changing epidemiology of these intestinal protozoa, as well as new approaches to diagnosis and treatment of these protozoa, are discussed.

Varioliform mucosal polypoid lesions in intestinal tract in a patient with adult T-cell leukemia

We describe a case of adult T-cell leukemia (ATL) with intestinal infiltration. In the early clinical stage, the endoscopic findings for the intestine were similar to those of amebic enterocolitis, i.e., varioliform mucosal polypoid lesions, and amebic cyst was detected with stool examination. Although no specific pathological factor could be identified on biopsy, the patient was treated for amebiasis as a diagnostic therapy. The findings of varioliform mucosal polypoid lesions were detected in the duodenum on endoscopic examination, but the lesions eventually disappeared during the treatment for amebiasis. We then suspected lymphoma partially masked by the amebiasis. Immunological staining of a specimen of the colonic mucosa revealed T cell invasion and Southern blotting demonstrated adult T-cell leukemia provirus invasion. Thus, ATL cell infiltration of the intestinal tract was confirmed. It is suggested that systemic disease should also be considered when varioliform mucosal polypoid lesions are found on colonoscopic examination.

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.

Gastrointestinal disease in the immunocompromised patient

Gastrointestinal (GI) disease is frequent in all types of immunocompromised patients but occurs with greatest frequency in patients with acquired immunodeficiency syndrome (AIDS). Thus, much of this review deals with human immunodeficiency virus (HIV)-related GI diseases. Gastrointestinal diseases in other immunocompromised patients are compared with those in patients with AIDS. Conditions unique to transplant recipients, such as graft-versus-host disease (GVHD) and posttransplant lymphoproliferative disorders (PTLDs), are discussed separately. We have divided these GI diseases into four main categories: (1) HIV-related inflammatory conditions other than opportunistic infections (HIV-related enteropathy, proctocolitis, and CD8 lymphocytosis); (2) inflammatory conditions unrelated to HIV or opportunistic infections (neutropenic enterocolitis, regional enteritislike enteropathy, and GVHD); (3) opportunistic infections (illnesses caused by herpesvirus, cytomegalovirus, and miscellaneous other viruses; Mycobacterium, Candida, Histoplasma, Cryptococcus, Cryptosporidium, Microsporida, Isospora, Leishmania, Toxoplasma and Strongyloides organisms as well as Pneumocystitis carinii; and (4) neoplasias (Kaposi's sarcoma [KS], AIDS-related non-Hodgkin's lymphoma [NHL], HIV-related Hodgkin's disease [HD], PTLDs, and miscellaneous neoplasms). The prevalence, pathogenesis, clinical manifestations, gross pathological findings, and microscopic features of each disease entity are discussed.

Case report: adult T-cell leukemia/lymphoma associated with recurrent strongyloides hyperinfection

Adult T-cell leukemia/lymphoma (ATLL) was demonstrated postmortem in a 47-year-old woman initially manifesting severe hypercalcemia and a vertebral compression fracture. Hyperinfection with Strongyloides stercoralis preceded the appearance of ATLL by several months and ultimately dominated the terminal course. Although HTLV-I and S. stercoralis commonly infect the same host, only three other cases of concomitant ATLL and hyperinfection have been reported in English. The apparent rarity of this association suggests that immunologic sequelae of ATLL do not predispose to dissemination and multiplication of Strongyloides. Observations pertinent to this conclusion are reviewed.

Cytokine induction in HTLV-I associated myelopathy and adult T-cell leukemia: alternate molecular mechanisms underlying retroviral pathogenesis

The human T-cell lymphotropic virus type I (HTLV-I) is capable of inducing a variety of host cellular genes including many of the cytokines responsible for immune regulation and osteoclast activation. This derangement in cytokine expression may contribute to the panoply of disease states associated with HTLV-I infection such as the adult T-cell leukemia (ATL) and HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP). We wished to determine if there was a correlation between the expression of an array of cytokines and the diverse clinical manifestations of ATL and HAM/TSP. Utilizing the techniques of specific mRNA amplification by the polymerase chain reaction (PCR) as well as Northern blotting, we analyzed the ex vivo mRNA expression of gamma-interferon (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and transforming growth factor-beta 1 (TGF-beta 1) in the peripheral blood of HAM/TSP and ATL patients as well as asymptomatic seropositive carriers. IFN-gamma, TNF-alpha, and IL-1 beta transcripts were up-regulated in patients with HAM/TSP and seropositive carriers when compared to their levels in ATL and normal controls. In contrast, the ATL patients constitutively expressed higher levels of TGF-beta 1 mRNA than HAM/TSP and seropositive carriers. In addition, TNF-alpha and IL-1 beta serum levels were elevated in HAM/TSP, but not in ATL patients nor seropositive carriers. However, the circulating leukemic cells from ATL patients secreted increased levels of TGF-beta 1 protein into the culture medium than T-cells derived from HAM/TSP patients. Collectively these results suggest that induction of IFN-gamma, TNF-alpha, and IL-1 beta in HAM/TSP may initiate an inflammatory cascade with subsequent events leading to immune mediated destruction of the central nervous system in these patients. Expression of osteoclast activators such as TNF-alpha and IL-1 beta is not associated with hypercalcemia in ATL. Finally, impaired cellular and humoral immune responses present in ATL, but not in HAM/TSP, may be related to elevated levels of TGF-beta 1 produced by the leukemic cells. These differences in retroviral-induced host cytokine expression in ATL and HAM/TSP suggest alternate roles in disease pathogenesis.