Enteric parasites and AIDS

Abstract

Amongst the causes of diarrhea in developing countries, those of a parasitic origin are prominent in patients with AIDS.Opportunistic infections caused by intestinal parasites also vary according to the geographical area and the endemic levels in each location.The progressive decline of immunological and mucous defense mechanisms predisposes patients to early, intermediary and late gastrointestinal manifestations of HIV infection. 6 At later stages of the disease, the alterations in non-specific defense mechanisms in the production of Ig A and the reduction in local immune cell response also progress, thus increasing the susceptibility to a number of intestinal opportunistic pathogens, among which Cryptosporidium parvum, Isospora belli and Microsporidia species are the most prominent. 7After the emergence of AIDS, these parasites, until then known solely in veterinary medicine, were no longer considered as commensal organisms and are nowadays recognized as opportunistic pathogens common to these patients. Infections by these agents constitute a major secondary aggravating factor of the disease, often responsible for worsening the general health conditions, due to manifestations of diarrhea which are difficult to control, sometimes resulting in the death of the patient. CRYPTOSPORIDIASISCryptosporidiasis, a disease caused by an intracellular protozoan named Cryptosporidium sp, was described for the first time in 1907 by Tyzzer. This parasite was considered a commensal up to 1975, when it was identified as the cause of diarrhea in animals. 8 The first manifestation of cryptosporidiasis was reported by Nine et al. in 1976, and the disease became a major concern when the notification of the first 21 patients was given, 14 of whom died of chronic diarrhea caused by Cryptosporidium sp infection. 9 It is worth noting that outbreaks of epidemic linked to contaminated water are of extreme importance for the dissemination of this parasite such as the 1993 Milwaukee (USA) cryptosporidiasis outbreak, in which 403,000 human cases were reported, thereby becoming a relevant public health concern.10-12 After this outbreak, it was recommended that immunocompromised patients should be extremely careful with water, foodstuffs and contact with animals.Cryptosporidiasis is distributed over all continents. In Haiti and the African continent the prevalence is 50%, 13 while in the USA it ranges from 3 to 4%.14 In Brazil, due to the continental size of the country, the rates of incidence vary with the location. In the city of São Paulo, for instance, reports have referred to levels around 12.1 to 24.44%. [15][16][17] However, the latest epidemiological report on Brazil, dated February 1998, shows a cryptosporidiasis rate of only 3.5%. 18Cryptosporidiasis in AIDS patients usually causes chronic, bulky and intermittent diarrhea, with liquid non-bloody stools, accompanied by pain and abdominal colic, and a noticeable loss of weight can be observed. 8Asymptomatic cases are rarely described, occurring mostly in developing countries with pati...

Intestinal parasitic infections in HIV/AIDS patients: epidemiological, nutritional and immunological aspects

“…According to these authors, intestinal parasites were detected in 63.9% of patients from the pre-HAART era and 24% in the HAART era, thus showing a reduction in prevalence between the two periods. Cimerman et al (2,12) found a prevalence of 24.4% for opportunistic parasites in the pre-HAART era and 6.8% after HAART introduction, with higher rates in patients with CD4 + T cells < 200/mm 3 . When comparing periods before and after HAART implementation, Nobre et al (13) observed prevalences of 2.8% and 1.1%, respectively, low in both eras, but even lower after HAART use.…”

“…Since the emergence of AIDS, clinical alterations related to the gastrointestinal tract have been highly prevalent, of which diarrheic conditions associated to parasitic infections are noteworthy (2). Many studies have shown that some intestinal parasites were frequently associated with severe diarrhea in HIV patients, both in developed and developing countries (2)(3)(4)(5)(6)(7)(8). Socioeconomic and cultural factors have carefully been studied for the impact that they may have on the onset of enteroparasitosis in general and in HIV-infected patients (9).…”

Fiscalização de verduras comercializadas no município de Ribeirão Preto, SP

“…A freqüência significativamente mais baixa de contaminação nas hortas em relação aos demais pontos de venda pode ser justificada por constituir o ponto inicial da cadeia de comércio e, principalmente, pelo programa de fiscalização de hortas implantado no município há 3 anos 34 . A presença da forma trofozoíta de Giardia sp sugere que a contaminação tenha sido evento recente, provavelmente por manipulação 29 no ponto de venda, visto ser esta forma muito frágil, não sobrevivendo por mais de 15 a 20 minutos no meio externo 7 . Constatamos vários sorotipos de Salmonella cuja importância não se restringe a quadros de gastrenterite mas também, como potenciais agentes causais de grave bacteremia 31 e de meningite resistente a múltiplos antibióticos 9 .…”

Prevalence and genetic characterization of Cryptosporidium spp. and Cystoisospora belli in HIV-infected patients

“…Since the beginning of the AIDS pandemic, opportunistic infections have been recognized as common complications of the HIV infection 8,29 . The rapid dissemination of this virus contributed to the increasing prevalence of opportunistic protozoa among HIV-infected patients, with Cryptosporidium spp.…”