HIV-related enteropathy in Zambia: a clinical, microbiological, and histological study

To investigate the etiology of chronic diarrhea associated with human immunodeficiency virus (HIV) infection in Lusaka, we studied 63 HIV-positive patients and 36 seronegative controls clinically and endoscopically. Stools were studied for morphology and for opportunist infections. Fifty-five percent of patients seropositive for HIV who presented with a history of chronic diarrhea had parasites; the most common were Cryptosporidium (32%), Isospora belli (16%), and Strongyloides stercoralis (6%). As indicated by villous blunting and inflammation on duodenal histology, those with diarrhea and parasites showed the most severe damage. We could not implicate mycobacteria or bacterial overgrowth as causes for the enteropathy associated with HIV.     

Intestinal parasitic infections in HIV/AIDS patients: experience at a teaching hospital in central Brazil

In order to verify the occurrence of intestinal parasitic infections in human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) patients, 100 HIV/AIDS patients (Group 1) and 85 clinically healthy individuals (Group 2) were submitted to coproparasitological examination. Intestinal parasites were detected in 27% of patients from Group 1 and in 17.6% from Group 2. In Group 1 the most frequent parasites were Strongyloides stercoralis (12%), with 2 cases of hyperinfection; Isospora belli, 7%; Cryptosporidium sp., 4%; with 1 asymptomatic case and hookworm, 4%. Of the infected patients from Group 1 who reported to be chronic alcoholics, 64.3% had strongyloidiasis. Only 6 of the 27 infected patients from Group 1 were on highly antiretroviral therapy (HAART). In Group 2 the most frequent parasites were S. stercoralis, 7.1%; hookworm, 7.1% and Giardia lamblia, 3.5%. In conclusion, diagnosing intestinal parasites in HIV/AIDS patients is necessary especially in those who report to be chronic alcoholics or are not on antiretroviral treatment.     

Detection of opportunistic and non-opportunistic intestinal parasites and liver flukes in HIV-positive and HIV-negative subjects

We assessed the frequency and distribution of infection with opportunistic and non-opportunistic intestinal parasites and the liver fluke, Opisthorchis viverrini, in HIV-seropositive and HIV-seronegative subjects. Age- and sex-matched HIV-seropositive (n = 78) and HIV-seronegative patients (n = 78) from two hospitals in Khon Kaen Province, Thailand, participated in this study from November 1998 to August 2000. These subjects were divided according to the presence of diarrhea and CD4 counts. A single stool sample was obtained and analyzed by using specific techniques. Opisthorchis viverrini, was the most common parasite (19.2%) in each group. The prevalence rates of Cryptosporidium spp (11.5%) and Strongyloides stercoralis (17.9%) in the HIV-seropositive group were significantly (p < 0.05) higher than those in the HIV-seronegative group (1.0% for Cryptosporidium spp and 7.7% for S. stercoralis infections). The prevalences of these two parasites were 28% for Cryptosporidium spp and 20% for S. stercoralis in HIV-seropositives with diarrhea and CD4 counts lower than 100 cells/mm3, and were higher compared with patients without diarrhea or with high CD4 counts. These results suggest that infection with these parasites increases during HIV infection. The epidemiological distribution of Cryptosporidium and S. stercoralis may have implications for AIDS-related diseases.     

Pulmonary strongyloidiasis in a patient receiving prednisolone therapy

Strongyloidiasis is widely distributed in tropical and subtropical areas. Disseminated strongyloidiasis may develop in patients with immunodeficiencies. In the absence of early diagnosis and treatment, the prognosis of disseminated strongyloidiasis is extremely poor. We report a case of pulmonary strongyloidiasis that was successfully treated. The patient was an 83-year-old woman who had been receiving long-term oral prednisolone therapy for uveitis. The patient visited our emergency department complaining of breathing difficulties and diarrhea. A chest X-ray revealed a diffuse enhancement of interstitial shadows. A bronchoalveolar lavage (BAL) was performed, and both Gram staining and Grocott's staining revealed the presence of multiple filariform larvae of Strongyloides stercoralis in the bronchoalveolar lavage fluid (BALF). A stool examination performed at the same time also yielded S. stercoralis. The patient was diagnosed as having pulmonary strongyloidiasis and was treated with thiabendazole and ivermectin, in addition to antimicrobial agents; her respiratory symptoms and diarrhea improved, and S. stercoralis was not detected in subsequent follow-up examinations thereafter. In endemic areas of S. stercoralis, pulmonary strongyloidiasis should be considered as part of a differential diagnosis if chest imaging findings like alveolar and interstitial shadow patterns or lobar pneumonia are seen in patients with immunodeficiencies.     

Why does HIV infection not lead to disseminated strongyloidiasis?

We investigated the hypothesis that host immunosuppression due to advancing human immunodeficiency virus (HIV) disease favors the direct development of infective larvae of Strongyloides stercoralis, which may facilitate hyperinfection and, hence, disseminated strongyloidiasis. To do this, we sought correlations between the immune status of the subjects and the development of S. stercoralis infections. Among 35 adults, there were significant negative rank correlations between CD4+ cell counts and the proportions of free-living male and female worms. Thus, in individuals with preserved immune function, direct development of S. stercoralis is favored, whereas, in individuals with lesser immune function, indirect development is relatively more common. These results may explain the notable absence of disseminated strongyloidiasis in advanced HIV disease. Because disseminated infection requires the direct development of infective larvae in the gut, the observed favoring of indirect development in individuals immunosuppressed by advancing HIV disease is not consistent with the promotion of disseminated infection.     

Epidemiological and clinical interaction between HTLV-1 and Strongyloides stercoralis

Strongyloides stercoralis is the most common human parasitic nematode that is able to complete a life cycle and proliferate within its host. The majority of patients with strongyloidiasis have an asymptomatic infection or mild disease. However, when autoinfection occurs, a high number of infecting larvae can gain access to the bloodstream by penetrating the colonic mucosa leading to a severe hyperinfection and the development of disseminated strongyloidiasis. The human T cell lymphotropic virus type 1 (HTLV-1) predominantly infects T cells and induces spontaneous lymphocyte proliferation and secretion of high levels of type 1 cytokines. Strongyloides stercoralis patients with HTLV-1 co-infection have a modified immunological responses against parasite antigens and co-infection has clinical implications for strongyloidiasis. The high production of IFN-gamma observed in patients co-infected with HTLV-1 and Strongyloides stercoralis decreases the production of IL-4, IL-5, IL-13 and IgE, molecules that participate in the host defence mechanism against helminths. Moreover, there is a decrease in the efficacy of treatment of Strongyloides stercoralis in patients co-infected with HTLV-1. Alterations in the immune response against Strongyloides stercoralis and the decrease in the efficacy of anti-parasitic drugs are responsible for the increased prevalence of Strongyloides stercoralis among HTLV-1 infected subjects and make HTLV-1 infection the most important risk factor for disseminated strongyloidiasis.     

Heterologous antigen extract in ELISA for the detection of human IgE anti-Strongyloides stercoralis

Strongyloides ratti larval extract was used for the standardization of ELISA to detect genus-specific IgE in human strongyloidiasis. Forty serum samples from monoinfected patients shedding S. stercoralis larvae (Group I), 40 from patients with other intestinal parasites (Group II), and 40 from copronegative healthy subjects (Group III) were analyzed. Genus-specific IgE levels (ELISA Index: EI) were significantly higher in the group I (EI = 1.43) than groups II (EI = 0.70) and III (EI = 0.71), showing positivity rates of 55%, 2.5% and 0%, respectively. Similarly, sera from copropositive patients had significantly higher levels of total IgE (866 IU/mL) as compared to those from group II (302 IU/mL) and III (143 IU/mL). A significant positive correlation was found between levels of Strongyloides specific-IgE and total IgE in sera from patients with strongyloidiasis. In conclusion, S. ratti heterologous extract showed to be a useful tool for detecting genus-specific IgE by ELISA, contributing for a better characterization of the immune response profile in human strongyloidiasis.     

Risk factors for strongyloidiasis hyperinfection and clinical outcomes

Strongyloidiasis, caused by Strongyloides stercoralis, consists of various clinical syndromes. Strongyloidiasis hyperinfection leads to morbidity and mortality particularly in immunocompromized patients. This study aimed to determine the risk factors for strongyloidiasis hyperinfection and clinical outcomes. The medical records for hospitalized patients infected with S. stercoralis at Ramathibodi Hospital during 1994-2005 were retrospectively reviewed. Risk factors for strongyloidiasis hyperinfection were determined. There were 123 episodes of strongyloidiasis in 111 patients. The mean age was 46.8 +/- 17.8 years; 61% were males. Of 123 episodes, 37 (30.1%) had strongyloidiasis hyperinfection; the others had chronic strongyloidiasis. All the patients with strongyloidiasis hyperinfection and 88.3% of those with chronic strongyloidiasis were immunocompromized (p = 0.032); 89.2% of the former and 55.8% of the latter had received corticosteroids (p < 0.001). There were no significant differences in the type of immunocompromized host and the corticosteroid dosage between the two groups (p > 0.05). The hyperinfection group had a lower mean serum protein (p = 0.026) and albumin (p = 0.027) but a higher frequency of sepsis (p = 0.029), asthma-like symptoms (p = 0.025), adult respiratory distress syndrome (p = 0.026), and a longer duration of treatment (p=0.004). By logistic regression, corticosteroids use was a risk factor for hyperinfection (OR = 6.5, 95% CI = 2.1-20.0, p = 0.001). Most of the patients were treated with albendazole or thiabendazole, with a cure rate of 76.9%, whereas other recent cases treated with ivermectin had an average cure rate of 83.3%. The overall mortality rate was 8.1%.     

Comparative sensitivity and specificity of ELISA and IHA for serodiagnosis of strongyloidiasis with larval antigens

Sera from 68 patients with parasitologically proven strongyloidiasis were tested by the ELISA and IHA tests using larval antigens prepared from Strongyloides stercoralis and Strongyloides ratti. The ELISA using the S. stercoralis antigen detected the greatest number of sero-reactors (83.8%), whereas the IHA using the S. ratti antigen detected the fewest (55.9%). In addition, the S. stercoralis antigen had higher geometric mean titers than the S. ratti antigen in both the ELISA and the IHA tests. Sera from 37 presumed normal individuals also were tested by IHA and ELISA and nonspecific reactions were seen only with the IHA test. When sera from patients with parasitic infections other than strongyloidiasis were tested, the only consistent cross-reactions were with those sera from patients who had occult filariasis and acute schistosomiasis.     

Disseminated infection due to strongyloides stercoralis in AIDS patients. A report of 2 cases

Strongyloides stercoralis is an intestinal nematode that infects humans worldwide. Infected patients with severe involvement of cellular immunity may develop a syndrome characterized by the dissemination of larvae throughout the body. Extraintestinal strongyloidiasis has been infrequently reported and despite the prevalence of the helminth in tropical and developing countries there are few cases reported in AIDS patients. Most patients with disseminated strongyloidiasis present with fever, cough, diarrhea and shortness of breath. Chest radiographs usually show diffuse infiltrates. The diagnosis has been made by finding the helminth in respiratory secretions or stool. Enteric organisms like Escherichia coli can often be isolated in the blood or cerebrospinal fluid. We report two cases of disseminated strongyloidiasis in AIDS patients, in which stercoralis larvae were detected in sputum and stool samples.     

Impairment of host immune response against strongyloides stercoralis by human T cell lymphotropic virus type 1 infection

A large-scale study was undertaken to clarify the prevalence rate of strongyloidiasis in Okinawa, Japan and to evaluate the relationship between strongyloidiasis and infection with human T cell lymphotropic virus type 1 (HTLV-1). The prevalence rate of Strongyloides stercoralis and HTLV-1 infection were 6.3% and 14.0%, respectively. Among 2,185 patients more than 50 years of age, the rate of S. stercoralis infection was significantly higher in patients with HTLV-1 infection compared with patients without HTLV-1 infection. In 252 patients treated with ivermectin, serum IgE levels and peripheral eosinophil counts were significantly lower in HTLV-1 co-infected patients compared with patients without HTLV-1 infection. In addition, the anthelmintic effect was significantly lower in patients with HTLV-1 infection compared with patients without HTLV-1 infection. Our prospective study demonstrated a prevalence rate for strongyloidiasis and HTLV-1 infections, and clearly demonstrated that co-infection with HTLV-1 impaired the immune response against S. stercoralis.     

Clinical presentation as a guide to therapy for travelers' diarrhea

To better define the role of antimicrobial therapy among U.S. travelers in Mexico, clinical and nonculture laboratory parameters were compared for 56 patients with shigellosis and 204 others with diarrhea of other causes. The presence of fever, stool mucus and blood, and fecal leukocytes were significantly more common among patients with shigellosis (p less than 0.001) who also tended not to present with mild diarrhea (p less than 0.05). However, clinical and laboratory parameters were either too insensitive or too nonspecific to be useful in identifying most cases of shigellosis or in excluding the likelihood of its presence. Patients with mild clinical presentations, regardless of etiology, experienced resolution of disease sooner than those with moderate to severe presentations (p less than 0.01), but withholding therapy from patients with mild presentations resulted in 48% of these patients remaining ill at the end of 48 hours. Based on these findings, the authors advise empiric use of antimicrobial agents in travelers with diarrhea associated with fever, bloody stools, or fecal leukocytes, and for all travelers with moderate and severe diarrhea. If therapy is withheld from patients with initially mild presentations, a proportion might still require therapy, possibly an antimicrobial agent, for optimal control of symptoms.     

Prevalence of intestinal parasitic pathogens among HIV-positive individuals in Iran

Parasites are important enteric pathogens among patients with human immunodeficiency virus (HIV) infection. There have been very few reports on the prevalence of intestinal parasites among such patients in Iran. To determine the prevalence of intestinal parasites among HIV-positive individuals, we collected single stool samples and analyzed them for detection of various intestinal parasites from 206 HIV-positive individuals with different immune status visited in different medical centers in Iran. The data were tested for statistical significance with chi(2) and Mann-Whitney U tests. The overall prevalence of intestinal parasites was 18.4% (95%CI: 13.7, 24.3). More specifically, the following parasites were identified: Giardia lamblia (7.3%), Blastocystis hominis (4.4%), Entamoeba coli (3.9%), and Cryptosporidium parvum (1.5%). Other parasites observed included Strongyloides stercoralis and Hymenolepis nana in two cases and Dicrocoelium dendriticum in one. Of the 38 patients who tested positive for intestinal parasites, 15 (39.2%) had diarrhea. Intestinal parasites were significantly more common among patients with diarrhea than those without (P < 0.001). Further, CD4 counts were significantly lower among individuals with diarrhea than those without (P < 0.001). This study highlights the importance of testing for intestinal parasites among Iranian HIV-positive patients, especially those with low immunity presenting with diarrhea.     

Atypical gastric presentation of strongyloidiasis in HIV-infected patient—case report

Strongyloides stercoralis is an intestinal helminth of systemic distribution, which, once in its host, has the ability to perpetuate itself through an autoinfection cycle, leading to chronic infection. In healthy hosts, the parasite usually does not cause any symptoms, or only mild symptoms that are limited mainly to the small intestine. However, in immunocompromised hosts, uncontrolled multiplication with massive infection may occur, causing hyperinfection syndrome or disseminated strongyloidiasis, which are both associated with high morbidity and mortality. There are few reports of gastric involvement, particularly presenting as ulcer in the stomach. We report a case of gastric ulcer caused by S. stercoralis in HIV-infected patient.     

Comparison of enzyme-linked immunosorbent assay and indirect immunofluorescence assay in the diagnosis of human strongyloidiasis.

BACKGROUND: An enzyme-linked immunosorbent assay (ELISA) and indirect immunofluorescence assay (IFA) were evaluated for serological diagnosis of human strongyloidiasis. METHODS: Serum specimens obtained from 46 individuals infected with Strongyloides stercoralis, 37 healthy persons and 381 persons with other parasitic infections were tested using an IgG-ELISA that used crude antigen of S. stercoralis filariform larvae and an IFA. Test sera were pre-incubated with antigens from Ascaris, Toxocara and hydatid protoscolices to remove non-specific antibodies. RESULTS: The sensitivity, specificity, positive predictive value and negative predictive value for ELISA were 93.5%, 96.1%, 72.9% and 99.2%, respectively, and those for IFA were 87%, 90.1%, 49.4% and 98.4%, respectively. Both assays showed false positivity in hydatidosis, ascariasis and toxocariasis; however, this was less common with ELISA. CONCLUSION: ELISA method using filariform larval antigen may be a sensitive and specific test for human strongyloidiasis, and may be preferable to IFA.     

Overwhelming strongyloidiasis: an unappreciated opportunistic infection.

Strongyloides stercoralis is an intestinal nematode which infects a large portion of the world's population. Individuals with infection confined to the intestinal tract are often asymptomatic but may have abdominal pain, weight loss, diarrhea, and other nonspecific complaints. Enhanced proliferation of the parasite in compromised hosts causes an augmentation of the normal life-cycle. Resultant massive invasion of the gastrointestinal tract and lungs is termed the hyperinfection syndrome. If the worm burden is excessive, parasitic invasion of other tissues occurs and is termed disseminated strongyloidiasis. A variety of underlying conditions appear to predispose to severe infections. These are primarily diseases characterized by immunodeficiency due to defective T-lymphocyte function (Table 1). Individuals with less severe disorders become compromised hosts because of therapeutic regimens consisting of corticosteroids or other immunosuppressive medication. The debilitation of chronic illness or malnutrition also predisposes to systemic stronglyloidiasis. The diagnosis of strongyloidiasis can be readily made by microscopic examination of concentrates of upper small bowel fluid, stool, or sputum. Important clues suggesting this infection include unexplained gram-negative bacillary bacteremia in a compromised host who may have vague abdominal complaints, an ileus pattern on X-ray, and pulmonary infiltrates. Eosinophilia is helpful, if present, but should not be relied upon to exclude the diagnosis. The treatment of systemic infection due to Strongyloides stercoralis with either thiabensazole 25 mg/kg orally twice daily is satisfactory if the diagnosis is made early. Because of several unusual features of this illness in compromised hosts, the standard recommendation for 2 days of therapy should be abandoned in such patients. Immunodeficiency, corticosteroids, and bowel ileus reduce drug efficacy. Thus a longer treatment period of at leuch as blind loops or diverticula necessitate longer treatment. Stool specimens and upper small bowel aspirates should be monitored regularly and treatment continued several days beyond the last evidence of the parasite. In particularly difficult situations where either worm eradication is impossible or reinfection is probable, short monthly courses of antihelminthic therapy seem to be effective in averting recurrent systemic illness. Finally, prevention of hyperinfection or dissemination due to Strongyloides stercoralis can be accomplished by screening immunocompromised hosts with stool and upper small bowel aspirate examinations. These would be especially important prior to initiating chemotherapy, or before giving immunosuppressive medications or corticosteroids to patients with nonneoplastic conditions such as systemic lupus erythematosus, nephrotic syndrome, or renal allografts.     

Prominence of IgG4 antibodies in the human responses to Strongyloides stercoralis infection

The participation of the four subclasses of IgG in the humoral response to Strongyloides stercoralis was assessed by analyzing total and parasite-specific responses of each IgG subclass in 20 patients with uncomplicated strongyloidiasis and 21 immunocompromised patients with extraintestinal disease. The total component of each subclass was normal in most patients. IgG4 antibodies (measured by ELISA) were the most prominent parasite-specific response in both groups. Specific IgG2 and IgG4 responses were significantly more elevated in immunocompetent than in immunosuppressed patients. When the reactivity of each IgG subclass was analyzed by immunoblotting on SDS-PAGE-separated larval antigens, IgG4 recognized more antigens than did any other subclass. No parasite antigens were selectively recognized by either clinical group. Thus the continuous antigenic stimulation of chronic strongyloidiasis may result in an enhanced IgG4 subclass response. However, no presence or absence of humoral responses specific for filariform larval antigens was associated with the extraintestinal dissemination of the parasite.     

Hemodialysis and strongyloidiasis: a presumed cause of eosinophilia able to mask the other

The authors report a case of recurrent strongyloidiasis in a former French soldier of the Indochina colonial war (1946-54). Strongyloidiasis was associated with inaugural renal failure (acute steroid-resistant interstitial-type), requiring permanent hemodialysis. Despite antiparasitic treatment, relapse with digestive and pulmonary symptoms occurred 10 years later, following chronic eosinophilia. This observation emphasises that in dialysed subjects, eosinophilia should always stimulate a search for parasitic etiologies before incriminating dialysis-material allergy. Strongyloidiasis is a self-perpetuating helminthiasis whose distribution area is far greater than the intertropical zone. It can be completely asymptomatic, appear as late digestive complications and be responsible for bacteraemic peaks with septic visceral localizations. It causes a chronic oscillating eosinophilia. Diagnosis is usually performed by iterative stool examinations by Baermann technique in order to detect Strongyloides stercoralis rhabditoid larvae. In dialysed patients with unexplained eosinophilia awaiting renal transplant, the options of systematic thiabendazole (50 mg/kg) or ivermectine (0.2 mg/kg) single-dose to overcame the risk of disseminated strongyloidiasis induced by immunosuppressive post-transplantation therapy could be debated.     

Disseminated strongyloidiasis with uncommon manifestations in Greece

Strongyloidiasis is a human intestinal parasitosis caused by the nematode Strongyloides stercoralis. In most cases the infection is subclinical, but rarely, disseminated strongyloidiasis may occur in debilitated or immunocompromised patients, and in those who receive immunosuppressive agents. In this report, we describe an unusual case of severe disseminated strongyloidiasis, with intestinal, pulmonary and neurological manifestations, in a previously healthy male. The onset of the disease was acute with headache and neck stiffness, due to subarachnoid-ventricular haemorrhage. During a protracted clinical course the patient developed diarrhoea, abdominal pain, recurrent paralytic ileus, pneumonitis and respiratory distress, malabsorption and weight loss, diagnosis was delayed due to the complicated course and rarity of the disease. The diagnosis finally established during evaluation for malabsorption by demonstrating larvae of S. stercoralis in the jejunal mucosal biopsy and faeces. Response to mebendazole treatment was prompt with complete recovery and resolution of all systemic manifestations. Early diagnosis and treatment of strongyloidiasis in the intestinal phase is critical in the prevention of dissemination, which may prove lethal due to life-threatening complications.     

Prevalence of strongyloides in Northern Thailand and treatment with ivermectin vs albendazole

The stools of 697 cases were examined by agar plate technique at Tambon Makam Luang, Sun Pa Tong district, Chiang Mai; there were Strongyloides stercoralis 15.9%,Opisthorchis viverrini 5.1%, intestinal fluke 0.1%. Treatment with ivermectin 78 cases and albendazole 33 cases of strongyloidiasis gave cure rates at 98.7% and 78.7%, respectively. Alkaline phosphatase in some patients were increased at mild level after treatment. Side effects in ivermectin group were anorexia, nausia, diarrhea, diffuse itching and drowsiness; and in albendazole group were nausia and diarrhea. The efficacy of single dose and mild side effects suggest ivermectin as drug of choice for strongyloidiasis treatment.