Incomplete recovery of the CD4+/CD8+ ratio is associated with the late introduction of antiretroviral therapy among people living with HIV infection

ABSTRACT Despite being subject to lower AIDS-related mortality rates and having a higher life expectancy, patients with HIV are more prone to develop non-AIDS events. A low CD4+/CD8+ ratio during antiretroviral therapy identifies people with heightened immune senescence and increased risk of mortality. In clinical practice, finding determinants of a low CD4+/CD8+ ratio may be useful for identifying patients who require close monitoring due to an increased risk of comorbidities and death. We performed a prospective study on the evolution of the CD4+/CD8+ ratio in 60 patients infected with HIV (80% males), who were subjected to two different antiretroviral regimens: early and deferred therapy. The initial CD4+/CD8+ ratio was ≤1 for 70% of the patients in both groups. Older age, CD4+ cell count at inclusion, Nadir CD8+T-cell count, and Initial CD4+/CD8+ ratio ≤ 1 were risk factors for lack of ratio recovery. In the multivariate analysis, a CD4+/CD8+ ratio > 1 at the start of the treatment was found to be a determinant factor in maintaining a CD4+/CD8+ ratio > 1. The nadir CD4+T-cell count was lower in the deferred therapy group (p=0.004), and the last CD4+/CD8+ ratio ≤1 was not associated with comorbidities. Ratio recovery was not associated with the duration of HIV infection, time without therapy, or absence of AIDS incidence. A greater improvement was observed in patients treated early (p=0.003). In contrast, the slope of increase was slower in patients who deferred treatment. In conclusion, the increase in the CD4+/CD8+ ratio occurred mostly for patients undergoing early strategy treatment and its extension did not seem to be related to previous HIV-related factors.

Comparison of clinical features of pneumocystis pneumonia complicated with acute respiratory failure between human immunodeficiency virus-infected patients and non-human immunodeficiency virus-infected immunocompromised patients / 中华传染病杂志

Objective:To compare the clinical characteristics and analyze the prognostic factors between human immunodeficiency virus (HIV)-infected patients and non-HIV-infected immunocompromised patients with pneumocystis pneumonia (PCP) complicated with acute respiratory failure (ARF) in intensive care unit (ICU).Methods:The clinical data of patients with PCP complicated with ARF admitted in ICU of The First Affiliated Hospital of Zhengzhou University and The Sixth People′s Hospital of Zhengzhou City between May 2018 and October 2020 were retrospectively reviewed. All subjects were divided into HIV-infected group and non-HIV-infected immunocompromised group. General characteristics and underlying diseases of patients in the two groups were analyzed. Laboratory parameters, treatment and outcomes between two groups were compared. Independent sample t test, Mann-Whitney U test and chi-square test were used for statistical analysis, and univariate and multivariate logistic regression models were used to identify the risk factors for the clinical outcome. Results:A total of 129 PCP complicated with ARF patients were enrolled, including 75 HIV-infected patients and 54 non-HIV-infected immunocompromised patients. Only 10.7%(8/75) patients of HIV-infected group received anti-retroviral therapy (ART), but none of the patients in either groups had previously received trimethoprim-sulfamethoxazole (TMP-SMX) for PCP prophylaxis. Acute physiology and chronic health evaluation (APACHE) Ⅱ score of HIV-infected group was 18.7±6.0, which was higher than that in non-HIV-infected immunocompromised group (13.1±4.4) when admitted in ICU ( t=-5.45, P<0.001). Hypoproteinemia was common in both groups. Ninety-six percent (72/75) of HIV-infected patients had CD4 + T lymphocyte counts lower than 200/μL and 84.0%(63/75) of patients had CD4 + T lymphocyte counts even lower than 50/μL, while 5.74%(31/54) of patients in non-HIV-infected immunocompromised group had CD4 + T lymphocyte counts lower than 200/μL. The CD4 + /CD8 + T lymphocyte counts ratio was 0.05(0.02, 0.12) in HIV-infected group, which was lower than that in non-HIV-infected immunocompromised group (0.96(0.64, 1.44)), and the difference was statistically significant ( Z=-9.16, P<0.001). The length of ICU stay and hospital stay of non-HIV-infected immunocompromised patients were 10.0(7.0, 14.0) days and 18.0(11.8, 32.5) days, respectively, which were both longer than those in HIV-infected patients (7.0(4.0, 9.0) days and 13.0(7.0, 23.0) days, respectively), and the differences were both statistically significant ( Z=-3.58 and -2.73, respectively, both P<0.050). The hospital mortality of HIV-infected patients was 57.3%(43/75), which was significantly higher than that in non-HIV-infected immunocompromised patients (38.9%, 21/54) ( χ2=4.27, P=0.039). Multivariable logistic regression identified that lactic dehydrogenase (LDH), C-reactive protein (CRP) and APACHE Ⅱ score were the risk factors for the clinical outcome of HIV-infected patients (odds ratio ( OR)= 1.006, 1.015 and 1.736, respectively, all P<0.050). The partial pressure of oxygen in arterial blood/fractional concentration of inspiratory oxygen (PaO 2/FiO 2), LDH and CD4 + T lymphocyte counts were the risk factors for the clinical outcome of non-HIV infected immunocompromised patients ( OR=0.970, 1.008 and 0.989, respectively, all P<0.050). Conclusions:PCP patients with ARF are critically ill with high mortality rate. LDH, CRP and APACHEⅡscore are predictors for prognosis of HIV-infected patients with PCP, while PaO 2/FiO 2, LDH and CD4 + T lymphocyte counts are predictors for prognosis of non-HIV infected immunocompromised patients with PCP.

Neumonía por Pneumocystis Jirovecii en paciente adolescente inmunosuprimido no VIH positivo: Un reporte de caso / Pneumocystis Jirovecii pneumonia in a non-HIV immunosuppressed adolescent patient: A case report

Resumen La neumonía en el paciente inmunocomprometido es un reto diagnóstico al cual el clínico se enfrenta cada vez con más frecuencia , al momento de hablar de infiltrados en vidrio esmerilado es menester tener siempre en cuenta la posibilidad de neumonía por Pneumocystis Jirovecii, que por mucho tiempo se pensó como una enfermedad propia del huésped inmunosuprimido con VIH, a través del tiempo se ha manifestado en pacientes con trasplantes de órgano sólido y de precursores hematopoyéticos, asociado a autoinmunidad, al uso crónico de corticoesteroides y más recientemente al uso de terapia biológicas. La descripción de esta enfermedad y sus métodos diagnósticos en huéspedes inmunosuprimidos no VIH no es del todo claro, sabemos que el tratamiento de elección en estos casos es el trimetropin-sulfametoxazol (TMP-SMX) el cual no cuenta con evidencia de alta calidad al momento de plantear una dosis ni un tiempo de duración establecidos. Presentamos el caso de un paciente con diagnóstico de glomerulonefritis por enfermedad de cambios mínimos corticodependiente y quien desarrolló neumonía por Pneumocystis Jirovecii confirmada por histopatología quien recibió tratamiento y tuvo un desenlace positivo.

Abstract The pneumonia in the immunocompromised patient is a diagnostic challenge that the clinician faces more and more frequently, every time we talk about ground glass infiltrates it is necessary to always take into account the possibility of pneumonia due to Neumocystis Jirovecii, which for a long time was thought as a disease of the immunosuppressed host with HIV, but that across the time it has manifested itself in patients with solid organ transplants and hematopoietic precursors, associated with autoimmunity, the chronic use of corticosteroids and more recently the use of biological therapy. The description of this disease and the diagnostic methods in non-HIV immunosuppressed hosts is not entirely clear, we know that the treatment of choice in these cases is trimethropin-sulfamethoxazole (TMP-SMX), which does not have high-quality evidence at the time of a dose or a time of established duration. We present the case of a patient diagnosed with glomerulonephritis due to corticodependent minimal change disease and who suffers from pneumocystis Jirovecii pneumonia confirmed by histopathology, which received treatment and had a positive outcome

Factores de riesgo en población no VIH con tuberculosis en Uruguay / Risk factors in non-HIV population with tuberculosis in Uruguay / Fatores de risco na população não-HIV com tuberculose no Uruguai

Resumen: Objetivo: Describir las características de la población de personas de 18 años o más con tuberculosis (TB) no coinfectadas con Virus de la Inmunodeficiencia Humana (VIH) en Uruguay en el período del 1 de enero de 2016 al 31 de diciembre de 2017. Métodos: Se obtuvieron los datos de la base de datos anonimizada del registro nacional de TB perteneciente a la Comisión Honoraria de Lucha Antituberculosa y Enfermedades Prevalentes (CHLA-EP) para todos los casos de TB bacteriológicamente confirmada en el período del 1/1/16 al 31/12/17. Se excluyó a todos los individuos menores de 18 años y a todos aquellos con diagnóstico positivo para el VIH. Se clasificó a dichos individuos según el sector del sistema de salud de pertenencia. Se analizó la frecuencia y proporción de variables reconocidas como vinculadas a la enfermedad para cada subgrupo. Resultados: Se registraron 1129 casos. La tasa de incidencia de TB para la población de 18 años o más no infectada por el VIH fue de de 21,8 casos cada 100.000 habitantes para el año 2016. Se observó una proporción de factores de riesgo relacionados al medio socioeconómico de 43,8% del total de la población; estos predominaron en el sector público con un 57,4%. La pérdida de seguimiento para el sector público fue de 12,8%, mientras que en el sector privado fue de 3,0%. Se vió un porcentaje de fallecimiento de 38,8% entre los desocupados. Conclusiones: Los factores de riesgo socioeconómicos predominaron en el sector público de salud. Dentro de estos, la desocupación fue la de mayor proporción y se asoció con mayor porcentaje de fallecimiento y pérdida de seguimiento como resultado de tratamiento con respecto a la población general. La mayoría de los casos presentaron la forma pulmonar, y dentro de la extrapulmonar la más frecuente fue la pleural.

Abstract. Objective: To describe the characteristics of the population with tuberculosis (TB), over the age of 18, without HIV infection in Uruguay in the period between January 1st, 2016 and December 31st, 2017. Methods: Data of TB cases confirmed by sputum culture between 1/1/16 and 12/31/17 was obtained from the anonymized data base of the national register of TB, which belongs to CHLA-EP. Individuals younger than 18 or with HIV infection were excluded. Patients included in this study were organized in two groups according to the following criteria: belonging to public health care and belonging to private health care. Frequency and proportion of different variables related to TB were analyzed in those groups. Results: 1129 cases were analyzed. The incidence rate of TB amongst the population of non-HIV uruguayans over the age of 18 was 21.8 per 100,000 in 2016. Risk factors related to socioeconomic status were observed in a proportion of 43.8% of the total population; these were more prevalent within the subpopulation that received public health care, with a proportion of 57.4%. Loss of follow-up for the public health care sector was seen in 12.8% of cases, while the private sector presented 3.0%. The percentage of death among the unemployed was of 38.8%. Conclusion: Socioeconomic risk factors were predominantly superior among patients belonging to public health services. Moreover, unemployment was the most frequent factor within that category, and those who presented this factor had higher percentage of death and loss of follow up as the final outcome of treatment, compared to the general population. Pulmonary tuberculosis was the most frequent clinical form, followed by tuberculosis pleurisy as the main form of extra pulmonary tuberculosis.

Resumo: Objetivo: Descrever as características da população de 18 anos ou mais de idade com tuberculose (TB) não co-infectada pelo Vírus da Imunodeficiência Humana (HIV) no Uruguai no período de 1 de janeiro de 2016 a 31 de dezembro de 2017. Métodos: Os dados foram obtidos do banco de dados anonimizado do registro nacional de TB pertencente à Comissão Honorária de Tuberculose e Doenças Prevalentes (CHLA-EP) para todos os casos de TB bacteriologicamente confirmada no período de 1/1/16 a 31/12/17. Todos os indivíduos com menos de 18 anos e todos com diagnóstico positivo de HIV foram excluídos. Esses indivíduos foram classificados de acordo com o setor do sistema de saúde dos membros. A frequência e proporção de variáveis reconhecidas como ligadas à doença para cada subgrupo foram analisadas. Resultados: 1129 casos foram registrados. A taxa de incidência de TB na população de 18 anos ou mais de idade não infectada pelo HIV foi de 21,8 casos por 100.000 habitantes até 2016. Foi observada uma proporção de fatores de risco relacionados ao ambiente socioeconômico de 43,8. % da população total; estes predominaram no setor público com 57,4%. A perda de acompanhamento para o setor público foi de 12,8%, enquanto no setor privado foi de 3,0%. Uma taxa de mortalidade de 38,8% foi observada entre os desempregados. Conclusões: Os fatores de risco socioeconômico predominaram no setor de saúde pública. Entre eles, o desemprego foi a maior proporção e foi associado a um maior percentual de óbitos e perda de seguimento como resultado do tratamento em relação à população em geral. A maioria dos casos apresentava a forma pulmonar e, na extrapulmonar, a mais frequente era a pleural.

Paradoxical upgradation response in non-HIV tuberculosis: Report of two cases

A paradoxical upgradation response in tuberculosis (TB) is defined as the worsening of a pre-existing tubercular lesion or the appearance of a new lesion in a patient whose clinical symptoms initially improved with anti-TB treatment. A paradoxical response is common in HIV patients in the form of immune reconstitution inflammatory syndrome. A similar kind of response can also be seen in immunocompetent patients. Here, we present two cases of non-HIV TB who initially improved with antitubercular therapy (ATT) but worsened thereafter. After excluding possibilities such as multidrug-resistant TB, treatment failure or a superadded infection, a paradoxical upgradation response was diagnosed. Both the cases improved after treatment with corticosteroids in addition to ATT.

Role of bronchoscopy in diagnosis of pulmonary infections in non-HIV immune compromised host

Background: The occurrence of pulmonary infections is a common life threatening complication in immunocompromised patients, necessitating timely diagnosis and specific treatment. In our study bronchoscopic diagnostic techniques that include fiber optic bronchoscopy (FOB) and bronchoalveolar lavage (BAL) were applied in non-HIV immunocompromised conditions to determine the aetiology infectious microorganisms and comparing the clinical characteristics with bronchoscopic yield and to assess the influence of these methods on therapeutic outcome in this population.Methods: This prospective observational study was conducted at Rajiv Gandhi Government General Hospital, Park Town, Chennai, for a period of 8 months from January 2016 � August 2016.After meeting the requirements of eligibility criteria, the study included 65 immunocompromised patients consecutively who presented with pulmonary diseases. The primary outcome measure was the diagnostic yield of bronchoscopy among non-HIV immunocompromised patients. The secondary outcome measures were collecting the data including etiology of different microorganisms and non-infectious causes of pulmonary diseases among non- HIV immunocompromised patients, comparing the symptoms at the time of presentation, different radiological pattern with bronchoscopic yield and comparing the different subgroups of non-HIV immunocompromised patients with regards to presenting symptoms, radiological patterns, bronchoscopic yield, treatment modification, different spectrum of infections and complications.Results: The mean age of the patients was 41.91 ranging from 15-74 years. Majority (n=36) patients showed chest symptoms alone. On bronchoscopy, 52 cases (80%) out of 65 showed positive results and negative result was noticed in 13 cases (20%). Among them bacterial infections were predominant with 24%. After BAL culture bacterial culture was positive in 23 (35%) patients and fungal culture was positive in 15 (23%) cases. After bronchoscopy, current treatment plan was changed in 37 patients and clinical improvement was seen in 26 cases i.e. yield of bronchoscopy was 71%. Minor complications were noticed in 16 cases after bronchoscopy.Conclusion: Our study concludes, in clinically stable patients FOB was the preferred technique for finding the cause of lung infiltrates in non-HIV immunocompromised patients. Because our results signifies that the yield of bronchoscopy was high (80%) despite empirical antimicrobial therapy.

Analysis of diagnosis and treatment of pneumocystis pneumonia in the non-HIV-infected patients with acute respiratory failure / 天津医药

@#Objective To improve diagnostic and therapeutic levels of pneumocystis pneumonia (PCP) in non-HIVinfected patients. Methods The clinical data (including clinical manifestation，laboratory examination, imaging features, diagnosis, treatment and prognosis) of sixteen non-HIV-infected patients with acute respiratory failure caused by PCP who were diagnosed in our intensive care units (ICU) during January 2015 to December 2017, were summarized and discussed. Results Almost all patients were immunocompromised by hormone or immunosuppresant before PCP (15/16). Fever, dry cough, and dyspnea were the first symptoms in all patients. The development of PCP was rapid. All patients showed acute respiratory failure [oxygen index: (85.8±16.8) mmHg]. Invasive ventilator support was required in 11 patients (68.8%), high flow oxygen therapy was used in 5 patients (31.2%). The chest CT characteristics indicated diffuse ground glass opacity. Two patients were found methenamine silver-stained positive in bronchoalveolar lavage fluid. Sixteen cases were positive for pneumocystis detected by PCR. Sixteen patients were treated with compound sulfonamide (SMZco)，caspofungin and corticosteroid. Eight patients were cured, 7 died and 1 case was given up and then died. The ICU length of stay was 3-29 days, average days (13.0±7.1). Conclusion PCP is a kind of opportunistic infection among patients who are treated with immunosuppressive agents. SMZco combined with caspofungin and corticosteroid is effective in the treatment of severe PCP patients.

Analysis of risk factors of non HIV pneumocystis jirovecii pneumonia patients complicated with cytomegaloviremia / 中华急诊医学杂志

Objective To investigate the risk factors and outcome of non HIV pneumocystis jirovecii pneumonia (non HIV-PJP) patients complicated with cytomegaloviremia. Methods A total of 101 non HIV-PJP patients treated in Beijing Union Medical College Hospital in 2014 were retrospective analyzed. The cytomegaloviremia was defined as plasma cytomegalovirus DNA (CMV-DNA) ≥ 500 copies/mL, and patients were divided into the cytomegaloviremia group and non cytomegaloviremia group. Demographics, clinical features, endoscopic appearance and treatment of patients in the two groups were analyzed. Chi-square test and other method of univariate statistical analysis were performed. Logistic regression analysis was used to analyze the independent risk factors for non-HIV-PJP combined cytomegaloviremia. Results Of the 93 non-HIV-PJP patients, the incidence of cytomegaloviremia were 44.1％. Univariate analysis showed that risk factors of PJP patients complicated with cytomegaloviremia were female, lymphocyte count, C-reactive protein (CRP), positive hexamine silver staining, positive pneumocystis jirovecii pneumonia DNA (PJP-DNA), and invasive mechanical ventilation. Multivariate logistic regression analysis showed that independent risk factors of PJP patients complicated with cytomegaloviremia were female (OR=4.222, 95％CI:1.453-12.271, P=0.008), coinfection of fungal (OR=10.113, 95％ (OR=10.113, 95％CI:1.38-74.102, P=0.023) and invasive mechanical ventilation (OR=4.62, 95％CI:1.478-14.444, P=0.008). Conclusions During the same hospital stay, the prevalence of non-HIV-PJP patients complicated with cytomegaloviremia was higher, and the independent risk factors were female, coinfection of fungal, and invasive mechanical ventilation.

Research Progress on the prophylaxis for pneumocystis pneumonia (PCP) in non-HIV immunocompromised patients / 中华急诊医学杂志

Pneumocystis pneumonia ( PCP) is a disease affecting immunocompromised patients.PCP among these patients is associated with significant morbidity and mortality.In this paper, the prevention crowd of prevention, the effective of prevention and means of prevention are reviewed.

Non-HIV AIDS presenting with adrenal histoplasmosis and pulmonary tuberculosis: a mesmerising case report and discussion.

Non-HIV AIDS or idiopathic CD4 lymphocytopenia (ICL) is an acquired immunodeficiency syndrome resulting in CD4 lymphopenia without any evidence of HIV infection or any other apparent cause of immunosuppression. A non-diabetic patient presented with adrenal histoplasmosis and UTI leading to adrenal failure. No immediate cause of immunosuppression was found, HIV, HTLV screening were negative. A CD4 count was done and the patient was found to be having non-HIV AIDS (idiopathic CD4 lymphocytopenia). He was treated and discharged. Few months later the patient presented again with adrenal failure & pulmonary tuberculosis. Adrenal FNAC showed persisting adrenal histoplasmosis. CD4 count found to be low again, but this time it was worse than the previous scenario

Progressive multifocal leukoencephalopathy in non HIV, splenectomised, 66 years old male A rare case report.

Progressive multifocal leukoencephalopathy (PML) is a rapidly progressive AIDS-defining disease of the central nervous system. PML affects up to 8% of patients with AIDS and in most cases is fatal within 3–5 months. We presented here a case of 66 years old male who is non HIV with past history of splenectomy, and diagnosed as progressive multifocal leukoencephalopathy which is very rare. Here, we presented this rare entity which may be difficult to diagnose although, histopathological examination helps greatly in the diagnosis of this condition but the specificity and sensitivity of JC virus DNA PCR in CSF are quite acceptable.

Clinical Applification of Combined Detection of Pencilliosis Marneffei in a Non-HIV-infected Child / 现代检验医学杂志

Objective To study the diagnostic value of pencilliosis marneffei (PM)in a non-HIV-infected child with the com-bined detection of aspergillosis galactomannan,fungus Glucan(1-3)-β-D and boold culuture.Methods The venous blood specimen from the child was collected for the quantified detection of aspergillosis galactomannan,fungus Glucan(1-3)-β-D. The growth and colonial morphology of fungus was inspected with the positive blood culture and the characteristics of fun-gus smear were observed under microscope.Results The result of aspergillosis galactomannan was 14.45 μg/L and fungus Glucan (1-3)-β-D 77.14 pg/ml.Penicillium marnrffei was identified using blood culture.It was mycelia form under 25℃ and the salouraud medium produced water soluble claret-red pigment produced.It was mycelia form under 35℃ and the colony was gyri creases,the characteristic broom-like hypha and separation hypha could be found under microscope.Conclusion It is effective for the early diagnosis and therapy of PM with the combination detection of aspergillosis galactomannan,fungus Glucan (1-3)-β-D and boold culuture and have better clinical diagnosis value.

Subdural empyma due to Mycobacterium fortuitum in a non-HIV patient.

A 14‑year‑old male child presented with high grade intermittent fever with altered sensorium since 5‑6 days and generalised seizures. On examination neck stiffness noticed with normal haemogram and chest X‑ray. CSF microscopy was normal and no growth seen in aerobic culture. CT scan showed loculated lesion. Drained pus showed acid fast organism and culture on Lowestein Jensen medium showed pale‑coloured growth on 3rd day. Organism identified as Mycobacterium fortuitum by biochemical test. Interesting aspect of this case was there is no history of trauma or injection and patient was negative for HIV antibody.

Neuritis óptica luética en pacientes no VIH: revisión a propósito de 2 casos / Syphilitic optic neuritis in non HIV patients: review on 2 cases report

Introduction: Syphilis was an important cause of ocular inflammation during the pre-antibiotic era. Nowadays, its prevalence has clearly diminished and, although there has been an arousal of its manifestations in the Central Nervous System, mostly among HIV (+) patients; ocular compromise, particularly optic neuritis, are still infrequent. Nevertheless, the consequences of a late medical treatment maintain the importance of considering this diagnosis as an option in many clinical scenarios. Method: Review of the actual literature from the experience of two cases we recently treated. Discussion: We present the physiopathology clinical manifestations, diagnosis and treatment of syphilis, specifically its neurological and ocular manifestations in HIV and no HIV patients, discussing whether is necessary to actively search for syphilis in patients consulting with optic neuritis. Conclusion: As VDRL is an accessible exam for the differential diagnostic of syphilis in patients cursing with optic neuritis, we propose to practice it always in every patient, we suspect this pathology.

Introducción: La sífilis fue en la época preantibiótica causa frecuente de inflamación ocular. Actualmente su prevalencia ha disminuido, y si bien hemos visto una recrudescencia de sus manifestaciones en el sistema nervioso central asociada a la enfermedad por VIH, las manifestaciones oculares, particularmente la Neuritis Óptica, siguen siendo muy infrecuentes. Sin embargo, las consecuencias del retraso de tratamiento antibiótico oportuno, obligan al médico a tener presente este diagnóstico en diversos escenarios clínicos. Método: Revisión bibliográfica a partir de la descripción de dos casos que tratamos recientemente. Discusión: Exponemos la fisiopatología, clínica, diagnóstico y tratamiento de la sífilis con consideraciones especiales en sus manifestaciones neurológicas y oftalmológicas, en paciente VIH como no VIH, discutiendo si es necesario buscar activamente la sífilis en casos de Neuritis Óptica. Conclusión: El VDRL como herramienta para realizar el diagnóstico diferencial en un cuadro de Neuritis Óptica es un examen accesible para el clínico, por lo que proponemos solicitarlo de rutina en todo paciente que presente esta patología.

Intestinal parasitic infections in HIV and non-HIV infected patients with chronic diarrhea in Thailand.

Chronic diarrhea is a common problem in AIDS patients, and enteric parasites are re-cognized as important causes. This study determined the prevalence of parasitic infections in HIV infected patients with chronic diarrhea. Ninety-one patients with AIDS who presented with chronic diarrhea and 103 patients who were HIV negative were enrolled in the study. Detection of stool parasites was made by microscopy of simple smear, formalin-ether concentration method, modified acid-fast and modified trichrome staining techniques. Species identification of microsporidia spores was made by transmission electron microscopy (TEM). Cases in which serial fecal examinations were negative were subjected to gastroduodenoscopy and/or colonoscopy. Parasitic infections were found in 51 (56%) AIDS patients with chronic diarrhea and in 18 (17%) non-HIV cases (p < 0.001). Microsporidia and Cryptosporidium parvum were the most common parasites found in HIV infected patients and were also significantly more prevalent than in non-HIV infected cases [29% vs 0% for microsporidia, (p < 0.001), and 25% vs 1% for C. parvum, (p < 0.001)]. Species identification of microsporidia spores in 26 patients using TEM revealed Enterocytozoon bieneusi in 19 cases. This study indicated that microsporidia and C. parvum are important pathogenic causes of chronic diarrhea in AIDS patients in Thailand.