Seasonality of cryptosporidiosis in children

Occurrence and genetic diversity of Cryptosporidium and Giardia in urban wastewater treatment plants in north-eastern Spain

This study was designed to investigate the presence and removal efficiency of Cryptosporidium and Giardia in wastewater treatment plants at the 20 most populated towns in Aragón (north-eastern Spain). Samples of influent and effluent wastewater and dewatered sewage sludge were collected seasonally from 23 plants and processed according to USEPA Method 1623. All samples from raw and treated wastewater tested positive for Giardia, at an average concentration of 3247±2039cysts/l and 50±28cysts/l, respectively. Cryptosporidium was identified in most samples from both raw (85/92) and treated (78/92) wastewaters in a concentration significantly lower than Giardia, at both influent (96±105oocysts/l) and effluent samples (31±70oocysts/l) (P<0.001). The (oo)cyst counts peaked in summer in most plants. The removal efficiency was higher for Giardia (1.06-log to 2.34-log) than Cryptosporidium (0.35-log to 1.8-log). Overall, high removal efficiency values were found for Giardia after secondary treatment based on activated sludge, while tertiary treatment (microfiltration, chlorination and/or ultraviolet irradiation) was needed to achieve the greatest removal or inactivation of Cryptosporidium. Most samples of treated sludge were positive for Giardia (92/92) and Cryptosporidium (45/92), at an average concentration of 20-593cysts/g and 2-44oocyst/g, respectively. The molecular characterization of Cryptosporidium oocysts and Giardia cysts were attempted at the SSU rRNA/GP60 and bg/tpi loci, respectively. G. duodenalis sub-assemblage AII was identified in all plants, with a large proportion of samples (15/47) harboring mixed assemblages (AII+B). Nine Cryptosporidium species and six subtypes were identified, with C. parvum IIaA15G2R1 being the most prevalent. The presence of significant numbers of (oo)cysts in samples of final effluents and treated sludge reveals the limited efficacy of conventional treatments in removing (oo)cysts and highlights the potential environmental impact and public health risks associated with disposal and reclamation of wastewater.

Molecular Analysis of the Enteric Protozoa Associated with Acute Diarrhea in Hospitalized Children

Pediatric diarrhea is a common cause of death among children under 5 years of age. In the current study, we investigated the frequency of intestinal parasites among 580 pediatric patients with chronic diarrhea. Parasitic protozoa (all species combined) were detected by molecular tools in 22.9% of the children and the most common parasite was Cryptosporidium spp. (15.1%). Blastocystis hominis was detected in 4.7%, Dientamoeba fragilis in 4%, Giardia duodenalis in 1.7%, and Entamoeba histolytica in 0.17%. Protozoan infections were observed among all regional groups, but prevalence was highest among Qatari subjects and during the winter season. Typing of Cryptosporidium spp. revealed a predominance of Cryptosporidium parvum in 92% of cases with mostly the IIdA20G1 subtype. Subtypes IIdA19G2, IIdA18G2, IIdA18G1, IIdA17G1, IIdA16G1, and IIdA14G1 were also detected. For Cryptosporidium hominis, IbA10G2 and IbA9G3 subtypes were identified. This study provides supplementary information for implementing prevention and control strategies to reduce the burden of these pediatric protozoan infections. Further analyses are required to better understand the local epidemiology and transmission of Cryptosporidium spp. in Qatar.

Occurrence of Cryptosporidium and Giardia in raw and finished drinking water in north-eastern Spain

This paper collects the first large-sample-size study on the presence of Cryptosporidium oocysts and Giardia cysts in drinking water plants at the 20 most populated towns in Aragón (north-eastern Spain). Samples of influent raw water and effluent finished water were collected from each plant during different seasons and processed according to USEPA Method 1623. Cryptosporidium oocysts and Giardia cysts were detected in samples collected from 55% and 70% plants, respectively, with nine plants being positive for both protozoa and only four plants being negative over the study period. Both parasites were identified in the raw water throughout the year, with a lower frequency in autumn and a peak in winter, at a mean concentration of 67±38 oocysts per 100l and 125±241 cysts per 100l. The turbidity of raw water was not related to the presence or concentration of (oo)cysts, and the (oo)cyst removal efficiency was not related to the type of water treatment. One or both pathogens were identified in the finished water in 7 out of 11 plants with a conventional treatment process (coagulation, flocculation, sedimentation, filtration, and disinfection processes) compared to 4 out of 9 plants that did not apply one of the pre-chlorination treatment steps. Protozoa were detected in the finished water of positive plants at a mean concentration of 88±55 oocysts per 100l and 37±41 cysts per 100l, and most of them excluded propidium iodide so were considered potentially viable. The ubiquity of these parasites in the drinking water sources and the inefficiency of conventional water treatment in reducing/inactivating them may present a serious public health issue in this geographical area.

Molecular genotyping and sub-genotyping of Cryptosporidium spp. isolates from symptomatic individuals attending two major public hospitals in Madrid, Spain

Infections by members of the protozoan genus Cryptosporidium are among the most common causes of human gastrointestinal illness worldwide. In Spain cryptosporidiosis is not a compulsory notifiable disease, so the actual burden of the infection in both clinical and general populations remains largely unknown. We present here data on the diversity and frequency of the Cryptosporidium species and sub-genotypes identified in symptomatic individuals seeking medical care in two major hospitals in Madrid, Spain, between December 2013 and January 2015. Initial detection of the parasite was conducted on a total of 122 stool samples collected from 120 patients by microscopy with modified Ziehl-Neelsen and/or immunochromatographic tests. We used immunofluorescence, PCR-based methods and sequence analyses of the 60-kDa (GP60) glycoprotein and the small subunit ribosomal RNA (SSU rRNA) genes for confirmatory purposes and to characterize Cryptosporidium isolates. A total of 110 patients were confirmed with cryptosporidiosis. Overall, 101 isolates were successfully sub-genotyped at the GP60 locus, and an additional seven at the SSU rRNA locus. The analyses of all amplicons defined 10 distinct sequence types representing the GP60 family sub-genotypes IbA10G2 (78.7%), IeA11G3T3 (3.7%) of C. hominis, and the GP60 family sub-types IIaA15G2R1 (5.6%), IIaA18G6R1 (0.9%), IIcA5G3a (0.9%), IIdA18G1 (0.9%), IIdA19G1 (0.9%), IIdA21G1 (0.9%), and IIdA22G1 (0.9%) of C. parvum. A single isolate was assigned to C. felis (0.9%), two C. parvum isolates (1.9%) could not be characterized at the sub-genotype level and an additional four isolates (3.7%) were not typable. These results strongly suggest that transmission of cryptosporidiosis is mostly anthroponotic in origin in the clinical sample under study. We expect that our molecular epidemiological data will make a significant contribution to unravel the actual epidemiological situation of cryptosporidiosis in Spain, providing health care and policy makers with solid baseline information to unavoidably improve the national surveillance system and allocate additional resources to research, diagnosis, and treatment of cryptosporidiosis.

The Risk of Reported Cryptosporidiosis in Children Aged <5 Years in Australia is Highest in Very Remote Regions

The incidence of cryptosporidiosis is highest in children <5 years, yet little is known about disease patterns across urban and rural areas of Australia. In this study, we examine whether the risk of reported cryptosporidiosis in children <5 years varies across an urban-rural gradient, after controlling for season and gender. Using Australian data on reported cryptosporidiosis from 2001 to 2012, we spatially linked disease data to an index of geographic remoteness to examine the geographic variation in cryptosporidiosis risk using negative binomial regression. The Incidence Risk Ratio (IRR) of reported cryptosporidiosis was higher in inner regional (IRR 1.4 95% CI 1.2–1.7, p < 0.001), and outer regional areas (IRR 2.4 95% CI 2.2–2.9, p < 0.001), and in remote (IRR 5.2 95% CI 4.3–6.2, p < 0.001) and very remote (IRR 8.2 95% CI 6.9–9.8, p < 0.001) areas, compared to major cities. A linear test for trend showed a statistically significant trend with increasing remoteness. Remote communities need to be a priority for future targeted health promotion and disease prevention interventions to reduce cryptosporidiosis in children <5 years.

A year-long study of Cryptosporidium species and subtypes in recreational, drinking and wastewater from the central area of Spain

A year-long longitudinal study was undertaken to evaluate the presence of Cryptosporidium spp. in drinking water treatment plants (DWTPs), wastewater treatment plants (WWTPs) and freshwater bathing beaches (FBBs) from the central area of Spain. Water samples were collected according to USEPA Method 1623, and concentrated by the IDEXX Filta-Max® system. Cryptosporidium species were detected based on PCR-restriction fragment length polymorphism and sequence analyses of the ssuRNA gene. C. hominis and/or C. parvum isolates were subtyped by DNA sequencing of the Gp60 gene. Among 150 samples, 23 (15.3%) were positive by IFAT and 40 (26.7%) by PCR. Cryptosporidium spp. was more frequent in WWTPs (26.2 and 50.8%) and FBBs (12.5 and 17.5%) by IFAT and PCR respectively. Effluent waters from DWTPs were negative for this parasite suggesting that they are suitable for public use. Tertiary treatment in the WWTPs demonstrated a high removal efficiency of Cryptosporidium in the samples evaluated. Cryptosporidium species identified included C. hominis, C. parvum, C. ubiquitum, C. andersoni and C. muris. Subtyping analysis revealed C. hominis IbA10G2 and IeA11G3T3 alleles, which is the first report of the latter in water samples. Cryptosporidium highest frequency was observed in winter and spring. Our data provide information about the occurrence and diversity of Cryptosporidium in water of human use from the central area of Spain.

Identification and molecular characterization of Cryptosporidium and Giardia in children and cattle populations from the province of Álava, North of Spain

The prevalence of and factors associated with the protozoan enteropathogens Cryptosporidium and Giardia have been investigated in selected children and cattle populations from the province of Álava (Northern Spain). The presence of these organisms was detected in fecal samples using commercially available coproantigen-ELISA (CpAg-ELISA) and immunochromatographic (ICT) assays. A total of 327 caregivers of children participants were asked to answer questions on risk factors potentially associated to the prevalence of Cryptosporidium and Giardia, including water-use practices, water sports and contact with domestic or pet animals. Molecular analyses were conducted using a nested-PCR technique to amplify the small-subunit (SSU) rRNA gene of Cryptosporidium and the triosephosphate isomerase (tpi) gene of Giardia. Cryptosporidium oocysts and Giardia cysts were found in 3 and 16 samples using the CpAg-ELISA, and in 5 and 9 samples using the ICT test, respectively. Cryptosporidium and Giardia were also found in 7 and 17 samples by CpAg-ELISA, and 4 and 14 samples by ICT, respectively, of 227 cattle fecal samples. The overall Cryptosporidium and Giardia infection prevalences, based on a Bayesian approach accounting for the imperfect sensitivities and specificities of both diagnostic tests, were estimated to 1.0% (95% BCI: 0.2%-2.8%) and 3.1% (1.5%-5.3%) in children and 3.0% (0.5%-9.2%) and 1.4% (0.0%-6.4%) in cattle, respectively. In humans, a single Cryptosporidium isolate was characterized as C. hominis. Of seven Giardia isolates, four were identified as assemblage B, two as assemblage A-II and one was a mixed assemblage B+A-II infection. No Cryptosporidium or Giardia isolates could be obtained from cattle samples. Although limited, these results seem to suggest that cattle are unlikely to be an important reservoir of zoonotic Cryptosporidium and/or Giardia in the province of Álava.

Under-notification of cryptosporidiosis by routine clinical and laboratory practices among non-hospitalised children with acute diarrhoea in Southern Spain

INTRODUCTION

In a prevalence study of 400 stool samples from non-hospitalised children under 7 years of age with diarrhoea, the presence of Cryptosporidium was evaluated.

METHODS

In addition to standard microbiological analyses used for testing for bacteria, parasites, adenoviruses and reoviruses, all samples were re-evaluated for the presence of Cryptosporidium by means of microscopy using a modified acid-fast staining technique, a rapid immunoassay for the qualitative detection of C. parvum and Giardia lamblia, the ImmunoCard STAT! test, and nested polymerase chain reaction (PCR). For identifying the genotypes of Cryptosporidium, the gene 18S ssu rRNA was amplified and sequenced.

RESULTS

Thirty-two samples were positive by microscopy, 26 by immunoassay and 61 by nested PCR. Twenty-seven of these organisms were identified as Cryptosporidium hominis, 31 as Cryptosporidium parvum and, in four samples, it was impossible to identify the species. C. parvum was significantly more frequent in girls and C. hominis was significantly more frequent in boys (Fisher's exact test, p = 0.034). Although Cryptosporidium is only notified in a very small number of patients (1-4%) with diarrhoea in Spain, the microorganism was identified by nested PCR in 15.1% of the samples.

CONCLUSION

This study, therefore, highlights the under-notification of infections caused by Cryptosporidium in Southern Spain and poses the question of whether its routine testing should be carried out in cases of gastroenteritis in children.

Global distribution, public health and clinical impact of the protozoan pathogen cryptosporidium

Cryptosporidium spp. are coccidians, oocysts-forming apicomplexan protozoa, which complete their life cycle both in humans and animals, through zoonotic and anthroponotic transmission, causing cryptosporidiosis. The global burden of this disease is still underascertained, due to a conundrum transmission modality, only partially unveiled, and on a plethora of detection systems still inadequate or only partially applied for worldwide surveillance. In children, cryptosporidiosis encumber is even less recorded and often misidentified due to physiological reasons such as early-age unpaired immunological response. Furthermore, malnutrition in underdeveloped countries or clinical underestimation of protozoan etiology in developed countries contribute to the underestimation of the worldwide burden. Principal key indicators of the parasite distribution were associated to environmental (e.g., geographic and temporal clusters, etc.) and host determinants of the infection (e.g., age, immunological status, travels, community behaviours). The distribution was geographically mapped to provide an updated picture of the global parasite ecosystems. The present paper aims to provide, by a critical analysis of existing literature, a link between observational epidemiological records and new insights on public health, and diagnostic and clinical impact of cryptosporidiosis.

Seasonality of cryptosporidiosis: A meta-analysis approach

OBJECTIVES

We developed methodology for and conducted a meta-analysis to examine how seasonal patterns of cryptosporidiosis, a primarily waterborne diarrheal illness, relate to precipitation and temperature fluctuations worldwide.

METHODS

Monthly cryptosporidiosis data were abstracted from 61 published epidemiological studies that cover various climate regions based on the Köppen Climate Classification. Outcome data were supplemented with monthly aggregated ambient temperature and precipitation for each study location. We applied a linear mixed-effect model to relate the monthly normalized cryptosporidiosis incidence with normalized location-specific temperature and precipitation data. We also conducted a sub-analysis of associations between the Normalized Difference Vegetation Index (NDVI), a remote sensing measure for the combined effect of temperature and precipitation on vegetation, and cryptosporidiosis in Sub-Saharan Africa.

RESULTS

Overall, and after adjusting for distance from the equator, increases in temperature and precipitation predict an increase in cryptosporidiosis; the strengths of relationship vary by climate subcategory. In moist tropical locations, precipitation is a strong seasonal driver for cryptosporidiosis whereas temperature is in mid-latitude and temperate climates. When assessing lagged relationships, temperature and precipitation remain strong predictors. In Sub-Saharan Africa, after adjusting for distance from the equator, low NDVI values are predictive of an increase in cryptosporidiosis in the following month.

DISCUSSION

In this study we propose novel methodology to assess relationships between disease outcomes and meteorological data on a global scale. Our findings demonstrate that while climatic conditions typically define a pathogen habitat area, meteorological factors affect timing and intensity of seasonal outbreaks. Therefore, meteorological forecasts can be utilized to develop focused prevention programs for waterborne cryptosporidiosis.

[Cryptosporidium hominis diarrhea outbreak and transmission linked to diaper infant use]

BACKGROUND AND OBJECTIVE

On the basis of several cases of cryptosporidiosis detected in a child day-care center, we stablished the extent of the outbreak and investigated causes of parasite transmission.

PATIENTS AND METHOD

A retrospective cohort study was designed on all children attending day-care center and care givers to determine their infection status and identify risk factors associated to the outbreak.

RESULTS

24 cases of cryptosporidiosis were detected, with an attack rate of 0.46 (24/52); 12 of them were parasitologycally confirmed. All care givers were negative for Cryptosporidium and none of them reported symptoms of acute gastroenteritis. Transmission pattern was compatible with person to person modes. Among the factors investigated, two were associated with the risk of disease: diaper wear (relative risk = 2.06; p = 0.059); and diarrhea in relatives (relative risk = 2.05; p = 0.01). In all confirmed cases, Cryptosporidium hominis (previously known as C. parvum, genotype 1), was identified.

CONCLUSIONS

Cryptosporidiosis should be considered as a possible cause of outbreaks of gastroenteritis at day-care centers. Increasing care on diaper changing practices, specially over children with diarrhea, may be the key factor to prevent transmission of Cryptosporidium.

Mystery of seasonality: getting the rhythm of nature

Seasonality, a systematic periodic occurrence of events over the course of a year, is a well-known phenomenon in life and health sciences. Understanding seasonal fluctuations in diseases patterns presents us with a major challenge. To develop efficient strategies for disease prevention and control, we need to grasp the main determinants of temporal variations and their interactions. This paper will introduce the notion of seasonality by outlining several of its factors, using as illustrations respiratory and enteric water- or food-borne infections.

Population-based laboratory surveillance for Giardia sp. and Cryptosporidium sp. infections in a large Canadian health region

BACKGROUND

Giardia lamblia (intestinalis) and Cryptosporidium parvum are the two most important intestinal parasites infecting North Americans but there is a paucity of active population-based surveillance data from Canada. This study determined the incidence of and demographic risk factors for developing Giardia sp. and Cryptosporidium sp. infections in a general Canadian population.

METHODS

Population-based laboratory surveillance was conducted among all residents of the Calgary Health Region (CHR; population approximately = 1 million) during May 1, 1999 and April 30, 2002.

RESULTS

Giardia sp. infection occurred at a rate of 19.6 per 100,000 populations per year. Although the yearly incidence was stable, a significant seasonal variation was observed with a peak in late summer to early fall. Males were at higher risk for development of this infection as compared to females (21.2 vs. 17.9 per 100,000/yr; relative risk (RR) 1.19; 95% confidence interval (CI), 1.00-1.40, p = 0.047), and there was a significant decrease in risk associated with an increasing age. Cryptosporidium sp. infection occurred at an overall rate of 6.0 per 100,000 populations per year although a large outbreak of Cryptosporidium sp. infections occurred in the second half of the summer of 2001. During August and September of 2001, the incidence of cryptosporidiosis was 55.1 per 100,000 per year as compared to 3.1 per 100,000 per year for the remainder of the surveillance period (p < 0.0001). Cryptosporidiosis was largely a disease of children with an incidence of 17.8 per 100,000 per year occurring among those aged < 20 years of age compared to 1.25 per 100,000 per year for adults > or = 20 years of age (RR 14.19; 95% CI, 9.77-21.11; p < 0.0001).

CONCLUSION

This study provides important information on the occurrence and demographic risk groups for acquisition of giardiasis and cryptosporidiosis in a non-selected Canadian population.

Prevalence of cryptosporidiosis among the villagers and domestic animals in several rural areas of Korea

The present study was undertaken to investigate the infection status of Cryptosporidium parvum in the villagers and the reservoir hosts in several rural areas in Korea. A total 5,262 fecal samples were collected from the inhabitants residing at Gangwon-do, Chungcheongbuk-do, Jeollanam-do, and Gyeongsangnam-do between the dates of September, 2001 to June, 2002. In addition, 1,453 fecal samples were collected from livestock reared in Gokseong-gun, Jeollanam-do and Chungju-si, Chungcheongbuk-do. All the fecal smears were prepared by formalin-ether sedimentation, and examined by light microscopy after modified acid-fast staining. The overall positive rate of human cryptosporidiosis was 3.3%. Gokseong-gun, Jeollanam-do showed a 8.2% positive rate and appeared as the highest endemic area among the surveyed areas. Haman-gun, Gyeongsangnam-do showed a 0.4% positive rate and was the lowest endemic area. The positive rate of livestock infection in Gokseong-gun, Jeollanam-do was 94%, which was more than ten times higher than that of Chungju-si, Chungcheongbuk-do (9.3%). From these results, it was revealed that cryptosporidiosis was an endemic disease in some rural areas of Korea, and the livestock could be an important source of human infection.

Cryptosporidiosis in Kuwaiti children: seasonality and endemicity

OBJECTIVE

To detect the incidence of cryptosporidial infection in children presenting with gastrointestinal symptoms at the local hospital in Kuwait.

METHODS

Over a period of 3 years, September 1995 to August 1997, a single fecal sample from 3549 children was analyzed by modified saframin-methylene blue (SM-B) staining and a direct immunofluorescence test for the presence of Cryptosporidium oocysts.

RESULTS

Cryptosporidium oocysts were detected in 51 (10%) children with diarrhea. Prevalence was highest (73%) in children > 2 years of age compared with children < 2 years of age. The maximum number of cases, 38 of 51 (75%), was seen during the months January to April, indicating a marked seasonal variation. Polyparasitism was common in children with diarrhea; however, 43 of the 51 (84%) children with cryptosporidiosis had cryptosporidium infection only. Blastocystis hominis and Endolimax nana were the most common parasites detected (38% and 15%, respectively). Forty-seven of the 51 (90%) children with cryptosporidiosis were Kuwaiti and gave no history of travel abroad, suggesting that the infection was acquired indigenously. Sociodemographic information on children with cryptosporidiosis suggests three possible modes of transmission of infection: drinking contaminated water stored in overhead water tanks, person to person, or contact with infected animals.

CONCLUSION

In this study, we observed water-borne transmission of cryptosporidium infection in children with diarrhea. The infection is seasonal and endemic.

Cryptosporidiosis in pediatric patients

Cryptosporidium was detected in 21 (3.8%) individual stool samples collected from 553 pediatric patients hospitalized in our center employing a Telemann concentration technique (formalin-ether-centrifugation) and stained with the modified Kinyoun method. The mean age of populations with Cryptosporidiosis (16 boys and 5 girls) was 11 months; 15 months for girls and 6.5 for boys. Ages of 81% of them were less than 19 months. Seventy-six per cent of patients lived on the outskirts of Buenos Aires and 71% lacked pretreated running water at home. In 62% of the cases parasitological diagnoses coincided with warm seasons. At diagnosis mucous (63%) or watery (36%) diarrhea was presented in 90% of the patients with a median of 5 (3-8) bowel movements per day. Fever was presented in 66% of patients while abdominal pain and vomits in 60% and 52%, respectively. The median time from hospitalization up to parasitologic diagnosis was 20 days. Concomitant diseases observed were malnutrition, acute leukemia, bronchiolitis, HIV infection, anemia, celiac disease, myelofibrosis, vitelline sac tumor, neutropenia, osteosarcoma and dehydration. Cryptosporidiosis in our environment seems to occur more frequently in children younger than 18 months of age; who present diarrhea; are immunodeficient; come from a low socioeconomical background; and who live in poor sanitary conditions with no potable running water.