Environmental sources of Cryptosporidium in an urban slum in northeastern Brazil

New insights into the detection and molecular characterization of Cryptosporidium with emphasis in Brazilian studies: a review

Cryptosporidium spp. is a pathogenic protozoan present in the gastrointestinal tract of several hosts. This protozoan was originally classified as within the Coccidia Class and has recently been reclassified to gregarine based on studies that observed the evolutionary phases from the process of excision and sequencing of the 18S rRNA gene. Molecular biology techniques have become diagnostic tools and have also been used to understand the epidemiology of Cryptosporidium spp., since several species of this genus are very similar morphologically and morphometrically. Molecular techniques have been used in the identification of parasites, at the species and subtypes levels and to study disease transmission. The laboratory diagnosis of human cryptosporidiosis can be made by parasite detection methods, such as optical microscopy, antigens or genetic material detection, as well as serum antibodies raised to Cryptosporidium spp. Molecular methods were developed and allowed, not only an extensive revision of the taxonomy, but also an improvement in the laboratory diagnosis. In Brazil, there are few reports of Cryptosporidium spp. outbreaks in humans and all of them took place in nurseries. A few epidemiological studies developed in Brazil have used molecular methods for the detection of Cryptosporidium spp., as well as genotyping studies of their species and subtypes. The use of real-time PCR, together with microscopy and immunochromatography techniques, would result in a more precise diagnosis of cryptosporidiosis. The analysis of genotypes, subtypes and clonality of Cryptosporidium could be useful to understand and define the prognosis and severity of infections.

Household Socioeconomic and Demographic Correlates of Cryptosporidium Seropositivity in the United States

BACKGROUND

Cryptosporidium are parasitic protozoa that infect humans, domestic animals, and wildlife globally. In the United States, cryptosporidiosis occurs in an estimated 750,000 persons annually, and is primarily caused by either of the Cryptosporidium parvum genotypes 1 and 2, exposure to which occurs through ingestion of food or water contaminated with oocytes shed from infected hosts. Although most cryptosporidiosis cases are caused by genotype 1 and are of human origin, the zoonotic sources of genotype 2, such as livestock, are increasingly recognized as important for understanding human disease patterns. Social inequality could mediate patterns of human exposure and infection by placing individuals in environments where food or water contamination and livestock contact is high or through reducing the availability of educational and sanitary resources required to avoid exposure.

METHODOLOGY/PRINCIPAL FINDINGS

We here analyzed data from the National Health and Nutritional Examination Survey (NHANES) between 1999 and 2000, and related seropositivity to Cryptosporidium parvum to correlates of social inequality at the household and individual scale. After accounting for the complex sampling design of NHANES and confounding by individual demographics and household conditions, we found impaired household food adequacy was associated with greater odds of Cryptosporidium seropositivity. Additionally, we identified individuals of non-white race and ethnicity and those born outside the United States as having significantly greater risk than white, domestic-born counterparts. Furthermore, we provide suggestive evidence for direct effects of family wealth on Cryptosporidium seropositivity, in that persons from low-income households and from families close to the poverty threshold had elevated odds of seropositivity relative to those in high-income families and in households far above the poverty line.

CONCLUSIONS/SIGNIFICANCE

These results refute assertions that cryptosporidiosis in the United States is independent of social marginalization and poverty, and carry implications for targeted public health interventions for Cryptosporidium infection in resource-poor groups. Future longitudinal and multilevel studies are necessary to elucidate the complex interactions between ecological factors, social inequality, and Cryptosporidium dynamics.

Intranasal vaccination in mice with an attenuated Salmonella enterica Serovar 908htr A expressing Cp15 of Cryptosporidium: impact of malnutrition with preservation of cytokine secretion

Cryptosporidium is a protozoan parasite associated with acute and persistent diarrhea that, even in asymptomatic persons, can impair normal growth and potentially cognitive and physical development in young children. The recent availability of the complete gene sequence for Cryptosporidium hominis antigen Cp15 allows examination of innovative vaccine regimens involving intra-nasal antigen priming with live bacterial vectors applicable to human populations. We used a recently described weaned mouse model of cryptosporidiosis, where nourished and malnourished vaccinated mice receive the Cp15 antigen recombinant with cytolysinA on a Salmonella serovar Typhi CVD 908-htr A vector, followed by parenteral exposure to antigen with adjuvant. After challenge with Cryptosporidium oocysts via gavage, parameters of infection and disease (stool shedding of parasites, growth rates) were quantified, and serum/lymphoid tissue harvested to elucidate the Cp15-specific adaptive immune response. In vaccinated nourished mice, the regimen was highly immunogenic, with strong antigen-specific IL-6 and IFN-γ secretion and robust Cp15-specific immunoglobulin titers. In vaccinated malnourished mice, secretion of cytokines, particularly IFN-γ, and antigen-specific humoral immunity were generally undiminished despite protein deprivation and stunted growth. In contrast, after natural (oral) challenge with an identical inoculum of Cryptosporidium oocysts, cytokine and humoral responses to Cp15 were less than one-fourth those in vaccinated mice. Nevertheless, vaccination resulted in only transient reduction in stool shedding of parasites and was not otherwise protective against disease. Overall, immunogenicity for a C. hominis antigen was documented in mice, even in the setting of prolonged malnutrition, using an innovative vaccine regimen involving intra-nasal antigen priming with a live enteric bacterial vector, that has potential applicability to vulnerable human populations irrespective of nutritional status.

Cryptosporidium infection in Brazil: implications for veterinary medicine and public health

The aim of this review paper is to report the results of cryptosporidiosis research in Brazil, mainly its occurrence in animals and implications for veterinary medicine and public health. An increasing number of papers related to Cryptosporidium spp. infection in Brazil are available at national and international literature. The main focus described in these papers is the occurrence of Cryptosporidium spp. in food, environmental samples, in humans and several animal species, particularly birds, cattle, dogs and cats. Using molecular biology techniques, most Cryptosporidium species and genotypes identified in other countries have been described in Brazil. In mammals, there are descriptions of infection by C. bovis, C. canis, C. felis, C. meleagridis, C. parvum, and the cervine genotype; in birds, the following species and genotypes have been described: C. baileyi, C. galli, C. meleagridis, C. parvum and the avian genotypes I, II and III. Several species have been described in humans, such as C. parvum, C. hominis, and some species adapted to animal hosts such as C. canis, C. felis and C. meleagridis.

Prevalência de Cryptosporidium spp. em animais domésticos de companhia da população idosa em Teresópolis, Rio de Janeiro, Brasil

OBJETIVO: Este estudo visa a destacar a prevalência da criptosporidiose em animais de companhia doméstica. MÉTODO: Foram elegíveis para o estudo todos os idosos (acima de 60 anos de idade) de ambos os sexos que tenham cães e / ou gatos em casa, vivendo na cidade de Teresópolis e que foram a um posto de vacinação no município durante o período das campanhas nacionais de vacinação contra a gripe em 2007 e 2008. RESULTADOS: Em 29,0% dos animais pesquisados detectou-se a presença de oocistos e em 28,7% foram observados 2 ou mais oocistos por campo. A prevalência de história de diarreia entre os 300 animais examinados foi de 27%, atingindo 29,5% em cães e 24,7% em gatos, não mostrando diferença estatisticamente significativa entre as espécies. CONCLUSÃO: Este fato indica lacunas a serem mais aprofundadas, uma vez que são poucos estudos que exploram a relação da criptosporidiose com os animais de companhia na população humana. Os resultados demonstram a importância de realização periódica de exames parasitológicos em cães com e sem diarreia para tratamento específico e adoção medidas de controle e profilaxia.

Cloning and characterization of the acidic ribosomal protein P2 of Cryptosporidium parvum, a new 17-kilodalton antigen

Cryptosporidium infection is commonly observed among children and immunocompromised individuals in developing countries, but large-scale outbreaks of disease among adults have not been reported. In contrast, outbreaks of cryptosporidiosis in the United States and Canada are increasingly common among patients of all ages. Thus, it seems likely that residents of regions where Cryptosporidium is highly endemic acquire some level of immunity, while residents of the developed world do not. A new immunodominant Cryptosporidium parvum antigen in the 15- to 17-kDa size range was identified as the Cryptosporidium parvum 60S acidic ribosomal protein P2 (CpP2). We developed a recombinant protein-based enzyme-linked immunosorbent assay for serologic population surveillance for antibodies that was 89% sensitive and 92% specific relative to the results of the large-format Western blot assay. The human IgG response is directed almost exclusively toward the highly conserved, carboxy-terminal 15 amino acids of the protein. Although IgG antibody cross-reactivity was documented with sera from patients with acute babesiosis, the development of an anti-CpP2 antibody response in our Peru study population correlated better with Cryptosporidium infection than with infection by any other parasitic protozoan. In Haiti, the prevalence of antibodies to CpP2 plateaus at 11 to 20 years of age. Because anti-CpP2 IgG antibodies were found only among residents of countries in the developing world where Cryptosporidium infection occurs early and often, we propose that this response may be a proxy for the intensity of infection and for acquired immunity.

Giardia spp. and Cryptosporidium spp. In the Ivaí Indigenous Land, Brazil

The objective of this study was to investigate the occurrence of cysts of Giardia spp. and oocysts of Cryptosporidium spp. in waters of the Ivaí Indigenous Land, Brazil. Samples of river and spring water and of treated water were filtered and analyzed by direct immunofluorescence (Merifluor kit, Meridian Bioscience, Cincinnati, Ohio). Of 21 samples, 7 from each locality, 3 (3/7, 42.8%) from a river were positive for Giardia (mean concentration 2.57 cysts/L), and 1 (1/7, 14.3%) was positive for Cryptosporidium (6 oocysts/L). From springs, 1 sample (1/7, 14.3%) was positive for Cryptosporidium (6 oocysts/L). One sample (1/7, 14.3%) from treated water was positive for both, with 4 oocysts/L and 2 cysts/L. Giardia was the more frequent protozoan present.

Environmental risk factors for Cryptosporidium infection in an island from Western Venezuela

Few investigations have been conducted on risk factors for Cryptosporidium infection in communities from developing countries. A study was conducted to determine the prevalence and risk factors for cryptosporidiosis in San Carlos island, Venezuela. A sample of 515 subjects (mean age +/- SD: 21.4 +/- 17.8 years) was surveyed. Single fecal specimens were collected and modified Ziehl-Neelsen carbolfuchsin staining of formalin-ether concentrate stools were examined for identification of the parasite. Infections with Cryptosporidium (67 of 515, 13%) were common. Prevalence of the parasite varied among sectors of the community; 34 of 67(50.7%) cases of cryptosporidiosis clustered in two sectors with extreme poverty. Variables strongly associated with a higher risk for the infection (p < 0.01) were residing in these sectors versus the remainder, living in a hut or small residence versus a brick or larger house, using an area of backyard rather than a toilet or latrine for defecation, and having contact with soil contaminated with human feces. Crowding was also a risk (p < 0.05). Contact with human feces contaminated-soil may be an important mode of transmission and poverty a predisposing factor for the infection.

Quality of water the slum dwellers use: the case of a Kenyan slum

As a result of rapid urbanization in a context of economic constraints, the majority of urban residents in sub-Saharan Africa live in slums often characterized by a lack of basic services such as water and sewerage. Consequently, the urban poor often use inexpensive pit latrines and at the same time may draw domestic water from nearby wells. Overcrowding in slums limits the adequate distance between wells and pit latrines so that micro-organisms migrate from latrines to water sources. Sanitary practices in these overcrowded slums are also poor, leading to contamination of these wells. This study sought to assess sanitary practices of residents of a Kenyan urban slum and fecal contamination of their domestic water sources. This cross-sectional study involved 192 respondents from Langas slum, Kenya. Forty water samples were collected from the water sources used by the respondents for laboratory analysis of coliforms. Of these 40 samples, 31 were from shallow wells, four from deep wells, and five from taps. Multiple-tube fermentation technique was used to enumerate coliform bacteria in water. The study found that most people (91%) in the Langas slum used wells as the main source of domestic water, whereas the rest used tap water. Whereas most people used pit latrines for excreta disposal, a substantial percentage (30%) of children excreted in the open field. The estimated distance between the pit latrines and the wells was generally short with about 40% of the pit latrines being less than 15 m from the wells. The main domestic water sources were found to be highly contaminated with fecal matter. Total coliforms were found in 100% of water samples from shallow wells, while 97% of these samples from shallow wells were positive for thermotolerant coliforms. Three out of the four samples from deep wells were positive for total coliforms, while two of the four samples were positive for thermotolerant coliforms. None of the samples from taps were positive for either total or thermotolerant coliforms. Because the presence of thermotolerant coliforms in water indicates fecal contamination, facilitated by the proximity between the wells and pit latrines, the study suggests that the pit latrines were a major source of contamination of the wells with fecal matter. However, contamination through surface runoff during rains is also plausible as indiscriminate excreta disposal particularly by children was also common. Owing to the fecal contamination, there is a high possibility of the presence of disease pathogens in the water; thus, the water from the wells in Langas may not be suitable for human consumption. To address this problem, treatment of the water at community or household level and intensive behavioral change in sanitary practices are recommended. Efforts should be made to provide regulated tap water to this community and to other slums in sub-Saharan Africa where tap water is not accessible. However, more sampling of different water sources is recommended.

A serological study of Cryptosporidium transmission in a periurban area of a Brazilian Northeastern city

OBJECTIVES

To study the prevalence of Cryptosporidium infection by measuring the levels of anti-Cryptosporidium IgG antibodies among people inhabiting three neighbourhoods of a periurban area of Salvador, Northeast of Brazil; and to investigate the effects of environmental sanitation measures, hygienic habits and household water supply, storage and handling on the frequency of these antibodies in sera of the studied population.

METHODS

Cryptosporidium inter-household transmission was studied by comparing the frequency of anti-Cryptosporidium IgG antibodies among people inhabiting areas with or without different environmental sanitation measures and intra-household transmission by comparing the presence of these antibodies in families with or without cases of diarrhoea, associated with the presence of Cryptosporidium oocysts in their stools. Children or family members with diarrhoeal episodes were evaluated parasitologically for Cryptosporidium infection by testing stool specimens with the Ritchie-modified formol-ether concentration and the acid-fast staining methods. All groups were serologically evaluated for parasite exposure by an indirect enzyme-linked immunosorbent assay.

RESULTS

A statistically significant difference was detected in the prevalence of Cryptosporidium infection between area 1 which had no environmental sanitation measures and area 3 which had improved environmental sanitation measures (P = 0.044). Most of the hygienic habits investigated did not correlate with the presence of anti-Cryptosporidium antibody in sera of the population studied. However, positive associations were found between both poor household water supply (OD = 0.17; 90% CI = 0.09-0.32; P = 0.0001) and drinking unboiled/unfiltered water (OD = 0.40; 90% CI = 0.24-0.67; P = 0.0002) with high levels of anti-Cryptosporidium antibodies in sera.

CONCLUSIONS

These data suggest that although uncorrected household water supply, storage and handling play an important role on Cryptosporidium transmission in periurban areas of developing country cities, like Salvador, Brazil, inadequate environmental conditions may also contribute to the spread of this parasite.

Heavy cryptosporidial infections in children in northeast Brazil: comparison of Cryptosporidium hominis and Cryptosporidium parvum

Cryptosporidium is an important cause of infectious diarrhoea worldwide, but little is known about the course of illness when infected with different species. Over a period of 5 years, Cryptosporidium was identified in the stools of 58 of 157 children prospectively followed from birth in an urban slum (favela) in northeast Brazil. Forty isolates were available for quantification and 42 for speciation (24 Cryptosporidium hominis and 18 C. parvum). Children with C. hominis shed significantly more oocysts/ml of stool (3.5 x 10(6) vs. 1.7 x 10(6)perml; P=0.001), and oocyst counts were higher among symptomatic children (P=0.002). Heavier C. parvum shedding was significantly associated with symptoms (P=0.004), and symptomatic C. parvum-infected children were significantly more likely than asymptomatic children to be lactoferrin-positive (P=0.004). Height-for-age (HAZ) Z-scores showed significant declines within 3 months of infection for children infected with either C. hominis (P=0.028) or C. parvum (P=0.001). However, in the 3-6 month period following infection, only C. hominis-infected children continued to demonstrate declining HAZ score and asymptomatic children showed even greater decline (P=0.01). Cryptosporidium hominis is more common than C. parvum in favela children and is associated with heavier infections and greater growth shortfalls, even in the absence of symptoms.

[Prevalence of Cryptosporidium sp. in institutionalized dogs in the city of São Paulo, Brazil]

OBJECTIVE

Dogs play an important role as infection source of human cryptosporidiosis. The objective of the study was to determine the prevalence of Cryptosporidium sp. in dogs as well as to compare two techniques of fecal analysis.

METHODS

Four-hundred and fifty canine fecal samples from the city of São Paulo were analyzed between 2003 and 2004. Fecal samples were randomly selected from dogs housed in a university veterinary hospital (group 1, n=200) and private kennels (group 2, n=250). The detection of Cryptosporidium was performed using modified Ziehl-Neelsen staining and Polymerase Chain Reaction (PCR) technique. Statistical analysis was performed using the two-tailed test of significance at 5% confidence interval (z critical=+/-1.645).

RESULTS

Only Cryptosporidium parvum oocysts were found. The prevalences found by light microscopy examination and PCR techniques were 8.8% and 9.5%, respectively. Young animals showed a lower frequency (5.5%) compared to adults (10.1%). There was no statistically significant difference in Cryptosporidium prevalence between males and females.

CONCLUSIONS

The prevalence of C. parvum in the canine population studied was similar to that one found in the literature and affects equally males and females. The use of PCR allowed the detection of more positive cases than light microscopy.

Identification of species and sources of Cryptosporidium oocysts in storm waters with a small-subunit rRNA-based diagnostic and genotyping tool

The identification of Cryptosporidium oocysts in environmental samples is largely made by the use of an immunofluorescent assay. In this study, we have used a small-subunit rRNA-based PCR-restriction fragment length polymorphism technique to identify species and sources of Cryptosporidium oocysts present in 29 storm water samples collected from a stream in New York. A total of 12 genotypes were found in 27 positive samples; for 4 the species and probable origins were identified by sequence analysis, whereas the rest represent new genotypes from wildlife. Thus, this technique provides an alternative method for the detection and differentiation of Cryptosporidium parasites in environmental samples.

New insights into human cryptosporidiosis

Cryptosporidium parvum is an important cause of diarrhea worldwide. Cryptosporidium causes a potentially life-threatening disease in people with AIDS and contributes significantly to morbidity among children in developing countries. In immunocompetent adults, Cryptosporidium is often associated with waterborne outbreaks of acute diarrheal illness. Recent studies with human volunteers have indicated that Cryptosporidium is highly infectious. Diagnosis of infection with this parasite has relied on identification of acid-fast oocysts in stool; however, new immunoassays or PCR-based assays may increase the sensitivity of detection. Although the mechanism by which Cryptosporidium causes diarrhea is still poorly understood, the parasite and the immune response to it probably combine to impair absorption and enhance secretion within the intestinal tract. Important genetic studies suggest that humans can be infected by at least two genetically distinct types of Cryptosporidium, which may vary in virulence. This may, in part, explain the clinical variability seen in patients with cryptosporidiosis.

Susceptibility and serologic response of healthy adults to reinfection with Cryptosporidium parvum

Healthy adults are susceptible to infection with small numbers of Cryptosporidium parvum oocysts, resulting in self-limited infection. We investigated if infection of humans with C. parvum is protective 1 year after primary exposure. At 1 year after a primary challenge with 30 to 10(6) oocysts, 19 healthy immunocompetent adults were rechallenged with 500 oocysts and monitored for the development of infection and/or illness. Oocyst excretion was quantitated by direct immunofluorescence with a C. parvum-specific monoclonal antibody, and anti-C. parvum antibodies in serum were detected by an enzyme-linked immunosorbent assay. Fewer subjects shed oocysts after the second exposure (3 of 19; 16%) than after the first exposure (12 of 19; 63%) (P < 0.005). Although the rates of diarrhea were comparable after each of the two exposures, the clinical severity as determined by the mean number of unformed stools passed was lower after reexposure (11.25 versus 8.62; P < 0.05). The number of anti-Cryptosporidium immunoglobulin G and A seroconversions increased after secondary exposure. However, the C. parvum serum antibody response did not correlate with the presence or absence of infection.

Association between Cryptosporidium infection and animal exposure in HIV-infected individuals

Cryptosporidium causes a debilitating illness in immunocompromised individuals, yet the source of sporadic Cryptosporidium infections is unknown. Because early cases of cryptosporidiosis were associated with animals, and pets are a source of companionship to individuals with AIDS, determination of the risk of cryptosporidiosis associated with pets is important. To assess this risk, we conducted a case-control study of HIV-infected individuals with and without cryptosporidiosis. No statistically significant difference in the rate of overall pet ownership, cat ownership, or bird ownership was found between the two groups. Dog ownership reached borderline statistical significance; 15 of 48 (31%) cases owned a dog, compared with 17 of 99 (17%) controls (odds ratio [OR] = 2.19; p = .05; 95% confidence interval [CI], 0.9-5.3). No statistically significant differences between cases and controls were found in the frequency of surface water ingestion, rural exposure, travel history, or contact with diarrheic individuals. Our findings indicate that pets do not represent a major risk factor for acquisition of Cryptosporidium for HIV-infected individuals. Whether dog ownership presents a minimal risk for cryptosporidiosis needs further investigation.

Cryptosporidiosis: an emerging, highly infectious threat

Cryptosporidium parvum, a leading cause of persistent diarrhea in developing countries, is a major threat to the U.S. water supply. Able to infect with as few as 30 microscopic oocysts, Cryptosporidium is found in untreated surface water, as well as in swimming and wade pools, day-care centers, and hospitals. The organism can cause illnesses lasting longer than 1 to 2 weeks in previously healthy persons or indefinitely in immunocompromised patients; furthermore, in young children in developing countries, cryptosporidiosis predisposes to substantially increased diarrheal illnesses. Recent increased awareness of the threat of cryptosporidiosis should improve detection in patients with diarrhea. New methods such as those using polymerase chain reaction may help with detection of Cryptosporidium in water supplies or in asymptomatic carriers. Although treatment is very limited, new approaches that may reduce secretion or enhance repair of the damaged intestinal mucosa are under study.

Cryptosporidium and cryptosporidiosis

The tiny, iodine- and chlorine-resistant protozoan oocysts of Cryptosporidium parvum, long recognized by veterinarians, have become increasingly noted as a cause of watery diarrhea in developed and developing countries throughout the world. For immunocompromised patients, particularly those with AIDS, this diarrhea can be severe and life-threatening. Clovis Martins and Richard Guerrant here discuss the increasing recognition of this important pathogen in immunocompetent patients as well, and outline new challenges to improved water treatment, immunologic and antiparasite chemotherapy.