Epidemiology of cryptosporidiosis among European AIDS patients

Detection of Cryptosporidium spp. and Giardia spp. in Environmental Water Samples: A Journey into the Past and New Perspectives

Among the major issues linked with producing safe water for consumption is the presence of the parasitic protozoa Cryptosporidium spp. and Giardia spp. Since they are both responsible for gastrointestinal illnesses that can be waterborne, their monitoring is crucial, especially in water sources feeding treatment plants. Although their discovery was made in the early 1900s and even before, it was only in 1999 that the U.S. Environmental Protection Agency (EPA) published a standardized protocol for the detection of these parasites, modified and named today the U.S. EPA 1623.1 Method. It involves the flow-through filtration of a large volume of the water of interest, the elution of the biological material retained on the filter, the purification of the (oo)cysts, and the detection by immunofluorescence of the target parasites. Since the 1990s, several molecular-biology-based techniques were also developed to detect Cryptosporidium and Giardia cells from environmental or clinical samples. The application of U.S. EPA 1623.1 as well as numerous biomolecular methods are reviewed in this article, and their advantages and disadvantages are discussed guiding the readers, such as graduate students, researchers, drinking water managers, epidemiologists, and public health specialists, through the ever-expanding number of techniques available in the literature for the detection of Cryptosporidium spp. and Giardia spp. in water.

Cryptosporidiosis: A zoonotic disease concern

Cryptosporidiosis is considered to be a crucial zoonotic disease caused by worldwide distributing parasitic protozoa called Cryptosporidium spp. Cryptosporidiosis becomes a major public health and veterinary concern by affecting in human and various host range species of animals. Essentially, its importance of infection is increasing because of the high incidence in young children, immunocompromised persons, or immunodeficiency syndrome patients, especially in HIV/AIDS, and it is also one of the most causes of mortality in those patients who infected with Cryptosporidium spp. as well as young animals. All domestic animal, livestock, wildlife, and human can be potential reservoirs that contribute Cryptosporidium spp. to food and surface waters and transmitted to other hosts through fecal-oral route. The oocyst stage of Cryptosporidium spp. can remain infective and resistant to various environmental exposure and also resistant to many general disinfecting agents including chlorination which normally used in water treatment. Therefore, the understanding of these zoonotic pathogens is very essential in both animal and human health. This review focuses on the biology, life cycle, transmission, diagnosis, treatment, prevention, and control of this protozoan infection to emphasize and remind as the significant One Health problem.

Prevalence of Cryptosporidium species among HIV positive asymptomatic and symptomatic immigrant population in Kashmir, India

BACKGROUND AND OBJECTIVES

Cryptosporidiosis has not been reported as an endemic disease in Kashmir, but high prevalence of Cryptosporidium sp. has been found among asymptomatic (non-diarrheic) HIV positive immigrants in present study. Due to increasing number of HIV positive immigrants in Kashmir, Cryptosporidium may become a public health problem in Kashmir.

MATERIALS AND METHODS

A total of 45 stool samples were obtained from symptomatic (diarrheic n = 9) and asymptomatic (non-diarrheic n = 36) patients infected with HIV. The stool samples were concentrated using formalin ethyl acetate concentration technique, stained with modified Kinyoun's cold stain and oocysts were identified by microscopy under 1000 x magnification. It was confirmed by detection of antigens in stool samples by ELISA.

RESULTS

It was established that all the patients studied were carriers of Cryptosporidium. In present study though 80% of patients were asymptomatic (non-diarrheic) and HIV positive which involved non-Kashmiri army personals and travelers (immigrants) but were carriers of Cryptosporidium and 20% of HIV positive patients were emigrants (local Kashmiri traders) who travelled different states of India were having diarrhea (symptomatic) as well as carrier of Cryptosporidium.

CONCLUSION

Though Cryptosporidium infection causes chronic diarrhea but in present study all HIV positive patients screened whether diarrheic or non-diarrheic were positive for Cryptosporidium. To prevent the transmission of Cryptosporidium oocyst in environment and endemic spread of cryptosporidiosis as non-diarrheic HIV positive population may be potential source of infection, obligatory laboratory testing for Cryptosporidium in HIV positive immigrant population like traders and travelers is highly recommended in order to have a better understanding of the cause of spread Cryptosporidium infection in Kashmir.

Cryptosporidium and Strongyloides stercoralis infections among people with and without HIV infection and efficiency of diagnostic methods for Strongyloides in Yirgalem Hospital, southern Ethiopia

Background

Cryptosporidiosis and strongyloidiasis have been reported to be associated with HIV/AIDS. The present study was designed to determine the prevalence of Cryptosporidium and Strongyloides stercoralis infections among people with and without HIV infection and also assess the efficient methods for detection of Strongyloides.

Findings

A cross-sectional study was conducted in Yirgalem Hospital, southern Ethiopia from March, 2007 to October, 2007. Demographic data and stool samples were collected from 384 individuals (192 from each HIV serogroup). Samples were processed using the modified Ziehl-Neelsen technique for detection of Cryptosporidium species. Stool samples were also processed using the direct saline mount, the formol-ether and the water-emergence techniques for diagnosis of S. stercoralis. The prevalence of Cryptosporidium and S. stercoralis among HIV infected individuals was 25% and 12.0%, respectively. HIV positive individuals had significantly higher rate of infection with Cryptosporidium (OR = 15.7; 95% CI 5.5 to 44.5) and S. stercoralis (OR = 6.4; 95% CI 2.2 to 18.9). Among the three diagnostic methods, the larvae of S. stercoralis were more efficiently detected by the water-emergence technique.

Conclusions

In this study, the prevalence of Cryptosporidium and S. stercoralis infections was significantly higher among people with HIV/AIDS. Educating HIV infected individuals to prevent acquisition of Cryptosporidium infection and screening for S. stercoralis using the water-emergence technique is likely to be helpful.

Clinical features & risk factors associated with cryptosporidiosis in HIV infected adults in India

BACKGROUND & OBJECTIVE

Cryptosporidiosis is a leading cause of protracted, life threatening diarrhoea in HIV infected patients. Although data on prevalence are available for Indian patients, no information on risk factors for transmission exists. We therefore undertook this study to identify risk factors for transmission of cryptosporidiosis in HIV infected adults.

METHODS

Both symptomatic (diarrhoeal) and asymptomatic HIV infected patients were screened for cryptosporidiosis. All Cryptosporidium spp. positive cases were enrolled in the study and interviewed to record socio-demographic information, water supply and animal contact. Data were analysed to study clinical features and potential association with species and genotype.

RESULTS

Of the 28 cryptosporidial infections identified on screening 111 HIV positive patients with diarrhoea, 10 (35.7%) had chronic diarrhoea, 14 (50%) had associated fever and 8 (28.6%) had nausea. Symptomatic patients had a significantly higher number of co-infections with other enteric parasites (P=0.04) than 20 asymptomatics of 423 HIV positive individuals screened. Eleven of 17 (64%) patients with potentially zoonotic infections had diarrhoea. Patients with zoonotic species (64%) also tended to have fever more frequently than those infected with C. hominis (58%). Association between area of residence, rural or urban, water source and contact with animals and acquisition of cryptosporidiosis was not statistically significant.

INTERPRETATION & CONCLUSION

Cryptosporidiosis is an important cause of morbidity in HIV infected individuals in India, resulting in chronic diarrhoea. Risk factors for potentially zoonotic transmission of cryptosporidiosis were described in this study, but larger studies need to be done for a clearer understanding of the transmission dynamics of different cryptosporidial species in developing countries.

Cryptosporidiosis in Saudi Arabia and neighboring countries

Cryptosporidium is a coccidian protozoan parasite of the intestinal tract that causes severe and sometimes fatal watery diarrhea in immunocompromised patients, and self-limiting but prolonged diarrheal disease in immunocompetent individuals. It exists naturally in animals and can be zoonotic. Although cryptosporidiosis is a significant cause of diarrheal diseases in both developing and developed countries, it is more prevalent in developing countries and in tropical environments. We examined the epidemiology and disease burden of Cryptosporidium in Saudi Arabia and neighboring countries by reviewing 23 published studies of Cryptosporidium and the etiology of diarrhea between 1986 and 2006. The prevalence of Cryptosporidium infection in humans ranged from 1% to 37% with a median of 4%, while in animals it was different for different species of animals and geographic locations of the studies. Most cases of cryptosporidiosis occurred among children less than 7 years of age, and particularly in the first two years of life. The seasonality of Cryptosporidium varied depending on the geographic locations of the studies, but it was generally most prevalent in the rainy season. The most commonly identified species was Cryptosporidium parvum while C. hominis was detected in only one study from Kuwait. The cumulative experience from Saudi Arabia and four neighboring countries (Kuwait, Oman, Jordan and Iraq) suggest that Cryptosporidium is an important cause of diarrhea in humans and cattle. However, the findings of this review also demonstrate the limitations of the available data regarding Cryptosporidium species and strains in circulation in these countries.

Epidemiology and clinical features of Cryptosporidium infection in immunocompromised patients

Cryptosporidium spp. are a major cause of diarrheal disease in both immunocompetent and immunodeficient individuals. They also cause waterborne disease in both the United States and United Kingdom. Studies on the mechanisms of immunity to cryptosporidiosis indicate the importance of the T-cell response. The spectrum and severity of disease in immunocompromised individuals with cryptosporidiosis reflect this importance since the most severe disease is seen in individuals with defects in the T-cell response. The most commonly studied group is that of patients with AIDS. These patients suffer from more severe and prolonged gastrointestinal disease that can be fatal; in addition, body systems other than the gastrointestinal tract may be affected. The widespread use of antiretroviral therapy does appear to be having a beneficial effect on recovery from cryptosporidiosis and on the frequency of infection in human immunodeficiency virus-positive patients. Other diseases that are associated with increased risk of severe cryptosporidiosis, such as primary immunodeficiencies, most notably severe combined immunodeficiency syndrome, are also predominantly associated with T-cell defects. Of the remaining groups, children with acute leukemia seem to be most at risk from cryptosporidiosis. There is less evidence of severe complications in patients with other malignant diseases or in those receiving immunosuppressive chemotherapy.

The Serologic response to Cryptosporidium in HIV-infected persons: implications for epidemiologic research

Advances in serologic assays for Cryptosporidium parvum have made serology an attractive surveillance tool. The sensitivity, specificity, and predictive value of these new assays for surveillance of immunocompromised populations, however, have not been reported. Using stored serum specimens collected for the San Francisco Men's Health Study, we conducted a case-control study with 11 clinically confirmed cases of cryptosporidiosis. Based on assays using a 27-kDa antigen (CP23), the serum specimens from cases had a median response immunoglobulin (Ig) G level following clinical diagnosis (1,334) and a net response (433, change in IgG level from baseline) that were significantly higher than their respective control values (329 and -32, Wilcoxon p value = 0.01). Receiver operator curves estimated a cutoff of 625 U as the optimal sensitivity (0.86 [0.37, 1.0]) and specificity (0.86 [0.37, 1.0]) for predicting Cryptosporidium infection. These data suggest that the enzyme-linked immunosorbent assay technique can be an effective epidemiologic tool to monitor Cryptosporidium infection in immunocompromised populations.

A new restriction fragment length polymorphism from Cryptosporidium parvum identifies genetically heterogeneous parasite populations and genotypic changes following transmission from bovine to human hosts

Length and restriction site polymorphism within a 2.8-kb threonine-rich open reading frame from Cryptosporidium parvum was identified and used to determine the genotypes of isolates from calves and humans. In agreement with observations of other genetic loci, all calf isolates were identical at this locus. In contrast, human isolates showed two profiles, one found exclusively in humans and one a superposition of both profiles, which were indicative of heterogeneous parasite populations. PCR fingerprints were consistent with a change in the genetic profile of C. parvum isolates following transmission from bovine to human hosts.