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Giardia duodenalisandCryptosporidiumspp. are common intestinal protozoa that can cause diarrhoeal disease. Although cases of infection withGiardiaandCryptosporidiumhave been reported in Alaska, the seroprevalence and correlates of exposure to these parasites have not been characterised. We conducted a seroprevalence survey among 887 residents of Alaska, including sport hunters, wildlife biologists, subsistence bird hunters and their families and non-exposed persons. We tested serum using a multiplex bead assay to evaluate antibodies to theGiardia duodenalisvariant-specific surface protein conserved structural regions and to theCryptosporidium parvum17- and 27-kDa antigens. Approximately one third of participants in each group had evidence of exposure toCryptosporidium. Prevalence ofGiardiaantibody was highest among subsistence hunters and their families (30%), among whom positivity was associated with lack of community access to in-home running water (adjusted prevalence ratio [aPR] 1.15, 95% confidence interval (CI) 1.02–1.28) or collecting rain, ice, or snow to use as drinking water (aPR 1.09, 95% CI 1.01–1.18). Improving in-home water access for entire communities could decrease the risk of exposure toGiardia.

Understanding endemic infectious disease risk factors through traditional epidemiological tools is challenging. Population-based case–control studies are costly and time-consuming. A case–case analyses using surveillance data addresses these limitations by using resources more efficiently. We conducted a case–case analyses using routine surveillance data reported by 16 U.S. states (2005–2015), wherein reported cases of salmonellosis were used as a comparison group to identify exposure associations with reported cases of cryptosporidiosis and giardiasis. Odds ratios adjusted for age and reporting state (aOR) and 95% confidence intervals (95% CI) were calculated. A total of 10 704 cryptosporidiosis cases, 17 544 giardiasis cases, and 106 351 salmonellosis cases were included in this analyses. When compared with cases of salmonellosis, exposure to treated recreational water (aOR 4.7, 95% CI 4.3–5.0) and livestock (aOR: 3.2; 95% CI: 2.9–3.5) were significantly associated with cryptosporidiosis and exposure to untreated drinking (aOR 4.1, 95% CI 3.6–4.7) and recreational water (aOR 4.1, 95% CI 3.7–4.5) were associated with giardiasis. Our analyses shows that routine surveillance data with standardised exposure information can be used to identify associations of interest for cryptosporidiosis and giardiasis.

Enteric pathogens have been related to child undernutrition. Whereas there are lots of data on enteric bacterial microbiota and infections, much less is known about the incidence of prevalence of intestinal colonisation with viruses or important parasitic species. This study assessed the presence of selected viruses and parasites in stools of 469, 354, 468 Malawian children at 6, 12 and 18 months. We also assessed environmental predictors of the presence of viruses and parasites among 6-month infants. Microbial presence was documented using real-time polymerase chain reaction (PCR). Enteroviruses were identified in 68%, 80% and 81% of the stool samples at 6, 12 and 18 months children, rhinovirus in 28%, 18% and 31%, norovirus in 24%, 22% and 16%, parechovirus in 23%, 17% and 17%, rotavirus in 3%, 1% and 0.6%,Giardia lambliain 9.6%, 23.5% and 26%, andCryptosporidium(spp.) in 6%, 8% and 2% of the 6, 12 and 18 months stool samples. Dry season (May–October) was associated with a low infection rate of enterovirus, norovirus andCryptosporidium(spp.). Higher father's education level, less number of person in the household and higher sanitation were associated with a low infection rate of enterovirus, norovirus and rotavirus, respectively. The results suggest that the prevalence of asymptomatic viral and parasitic infections is high among Malawian children and that the family's living conditions and seasonality influence the rate of infections.

Although the impact of diarrhoeal disease on paediatric health in Nigeria has decreased in recent years, it remains an important cause of morbidity and mortality in children under 5 years. Rotavirus is recognised as an important aetiological agent, but information on the contribution of intestinal protozoa to watery diarrhoea in this age group in Nigeria is scarce. In this cross-sectional study, faecal samples from children admitted to healthcare centres in Abakaliki, Nigeria with acute watery diarrhoea (N = 199) and faecal samples from age-matched controls (N = 37) were examined for Cryptosporidium and Giardia using immunofluorescent antibody testing and molecular methods. Cryptosporidium was identified in 13 case samples (6.5%) and no control samples. For three samples, molecular characterisation indicated C. hominis, GP60 subtypes IaA30R3, IaA14R3 and IdA11. Giardia was not detected in any samples. This contrast in prevalence between the two intestinal protozoa may reflect their variable epidemiologies and probably differing routes of infection. Given that these two parasitic infections are often bracketed together, it is key to realise that they not only have differing clinical spectra but also that the importance of each parasite is not the same in different age groups and/or settings.

In June 2015, an outbreak of cryptosporidiosis with 35 cases (23 probable and 12 laboratory-confirmed) occurred among 191 attendees of a residential rehabilitation holiday for paediatric organ transplant patients (n= 49) and their families at a hotel in Somogy county, Hungary. The overall attack rate was 18%. Most of the cases were transplanted children who experienced severe acute disease and required adjustment to their tacrolimus immunosuppression. A retrospective case-control study suggested an association between recreational water exposures and illness: cases were seven times more likely than controls to have swum in the children's pool (odds ratio 7.17; 95% confidence interval 2.9–17.2;P< 0.0001) and five times more likely to have used the jetted whirlpool (odds ratio 5.25; 95% confidence interval 2.1–13.1;P< 0.0001). This was the first outbreak of cryptosporidiosis in Hungary and it is especially unfortunate that it affected vulnerable children who experienced severe symptoms.Cryptosporidiumpresents specific infection control difficulties in treated recreational water venues; the link to a whirlpool is unusual and highlights the importance of the age-appropriate use of these facilities and reminding users not to immerse their heads or swallow the water. Cryptosporidiosis is more commonly linked to children’ pools where improved bather hygiene and promoting exclusion of diarrhoea cases could help to avoid similar outbreaks.

SUMMARYWaterborne illness related to the consumption of contaminated or inadequately treated water is a global public health concern. Although the magnitude of drinking water-related illnesses in developed countries is lower than that observed in developing regions of the world, drinking water is still responsible for a proportion of all cases of acute gastrointestinal illness (AGI) in Canada. The estimated burden of endemic AGI in Canada is 20·5 million cases annually – this estimate accounts for under-reporting and under-diagnosis. About 4 million of these cases are domestically acquired and foodborne, yet the proportion of waterborne cases is unknown. There is evidence that individuals served by private systems and small community systems may be more at risk of waterborne illness than those served by municipal drinking water systems in Canada. However, little is known regarding the contribution of these systems to the overall drinking water-related AGI burden in Canada. Private water supplies serve an estimated 12% of the Canadian population, or ~4·1 million people. An estimated 1·4 million (4·1%) people in Canada are served by small groundwater (2·6%) and surface water (1·5%) supplies. The objective of this research is to estimate the number of AGI cases attributable to water consumption from these supplies in Canada using a quantitative microbial risk assessment (QMRA) approach. This provides a framework for others to develop burden of waterborne illness estimates for small water supplies. A multi-pathogen QMRA ofGiardia, Cryptosporidium, Campylobacter, E. coliO157 and norovirus, chosen as index waterborne pathogens, for various source water and treatment combinations was performed. It is estimated that 103 230 AGI cases per year are due to the presence of these five pathogens in drinking water from private and small community water systems in Canada. In addition to providing a mechanism to assess the potential burden of AGI attributed to small systems and private well water in Canada, this research supports the use of QMRA as an effective source attribution tool when there is a lack of randomized controlled trial data to evaluate the public health risk of an exposure source. QMRA is also a powerful tool for identifying existing knowledge gaps on the national scale to inform future surveillance and research efforts.

SUMMARYIn March 2013, a veterinary student tested positive forCryptosporidium; four classmates reported similar gastrointestinal symptoms. We aimed to identify source(s) and risk factors forCryptosporidiuminfection in university persons symptomatic between 21 January and 14 April 2013. Sixty-four (79%) students from a cohort of 81 fourth-year veterinary students completed questionnaires, identifying 13 cases; four wereCryptosporidium parvumGP60 subtype IIaA16G1R1b, two were IIdA24G1, seven did not submit stool samples. Thirteen cases attended the university's field clinic before symptom onset (13/37 attendees, 35%); 11 visited at least one of four farms where students recalled seeing calves with diarrhoea.C. parvumsubtype IIaA16G1R1b was identified in calves at one of the farms. Entering pens of calves with diarrhoea [relative risk (RR) 7·6, 95% confidence interval (CI) 1·7–33·5] and eating in clinic cars (RR 9·1, 95% CI 1·3–65·8) were associated with being a case. Washing hands at least twice per farm visit (0 cases,P= 0·03) was protective. This outbreak investigation was notable for rapid and effective collaboration between public health, veterinary and environmental sectors, leading to swift identification of a microbiological and epidemiological link between cases, infected calves and their farms. We recommend frequent hand-washing using proper technique and dissuasion from eating in clinic cars to minimize possible exposure to contaminated surfaces.

SUMMARYOpen-water swimming is increasingly popular, often in water not considered safe for bathing. Limited evidence exists on the associated health risks. We investigated gastrointestinal illness in 1100 swimmers in a River Thames event in London, UK, to describe the outbreak and identify risk factors. We conducted a retrospective cohort study. Our case definition was swimmers with any: diarrhoea, vomiting, abdominal cramps lasting ⩾48 h, nausea lasting ⩾48 h, with onset within 9 days after the event. We used an online survey to collect information on symptoms, demographics, pre- and post-swim behaviours and open-water experience. We tested associations using robust Poisson regression. We followed up case microbiological results. Survey response was 61%, and attack rate 53% (338 cases). Median incubation period was 34 h and median symptom duration 4 days. Five cases had confirmed microbiological diagnoses (four Giardia, one Cryptosporidium). Wearing a wetsuit [adjusted relative risk (aRR) 6·96, 95% confidence interval (CI) 1·04–46·72] and swallowing water (aRR 1·42, 95% CI 1·03–1·97) were risk factors. Recent river-swimming (aRR 0·78, 95% CI 0·67–0·92) and age >40 years (aRR 0·83, 95% CI 0·70–0·98) were protective. Action to reduce risk of illness in future events is recommended, including clarification of oversight arrangements for future swims to ensure appropriate risk assessment and advice is provided.

SUMMARYFaecal samples from 804 cattle and buffaloes and 165 diarrhoeal children of Ismailia province were investigated by an immunochromatographic screening test and PCR to determine prevalences and distributions ofCryptosporidiumspp. Results were analysed statistically for clustering of animal and human cases.Cryptosporidiumherd prevalence was 73·3% and individual animal prevalence 32·3%.C. parvumwas the dominant species in animals (65·7%). Young calves watered with canal or underground water were at particular risk of infection. Detection rates were higher when calves showed diarrhoea, fever and dehydration. HumanCryptosporidiumprevalence was 49·1%.C. hominisdominated in humans (60·5%), followed byC. parvum(38·3%). Living in villages, drinking underground water and having contact with animals were risk factors. Cluster analysis revealed differences in the distribution of infections between animals and humans and suggests different transmission dynamics.

SUMMARYPrevious evidence has suggested an association between cryptosporidiosis and consumption of unfiltered drinking water from Loch Katrine in Scotland. Before September 2007, the water was only micro-strained and chlorinated; however, since that time, coagulation and rapid gravity filtration have been installed. In order to determine risk factors associated with cryptosporidiosis, including drinking water, we analysed data on microbiologically confirmed cases of cryptosporidiosis from 2004 to 2010. We identified an association between the incidence of cryptosporidiosis and unfiltered Loch Katrine drinking water supplied to the home (odds ratio 1·86, 95% confidence interval 1·11–3·11, P = 0·019). However, while filtration appears to be associated with initially reduced rates of cryptosporidiosis, evidence suggests it may paradoxically make those consumers more susceptible to other transmission routes in the long-term. These findings support implementation of similar treatment for other unfiltered drinking-water supplies, as a means of reducing cryptosporidiosis associated with drinking water.

SUMMARYA total of 207 wild rodents were caught on nine pig farms, five chicken farms and five non-farm locations in Sweden and surveyed for a selection of bacteria, parasites and viruses.Lawsonia intracellulariaand pathogenicYersinia enterocoliticawere only detected in rodents on pig farms (9% and 8% prevalence, respectively) which indicate that these agents are more likely to be transmitted to rodents from pigs or the environment on infected farms.Brachyspira hyodysenteriae(1%),Brachyspira intermedia(2%),Campylobacter jejuni(4%),Campylobacter upsaliensis(2%), leptospires (7%) and encephalomyocarditis virus (9%) were also detected from rodents not in contact with farm animals.GiardiaandCryptosporidiumspp. were common, although no zoonotic types were verified, andSalmonella entericawas isolated from 1/11 mice on one farm but not detected by PCR from any of the rodents.Trichinellaspp. andToxoplasma gondiiwere not detected.

SUMMARYAn outbreak of cryptosporidiosis associated with exposure to outdoor swimming-pool water affected an estimated 800–1000 individuals. PCR products were obtained from faecal specimens from 30 individuals who tested positive forCryptosporidiumoocysts. RFLP and sequencing analyses showed that all individuals were infected withCryptosporidium parvum. Among the infected individuals, five had just swum in an adjacent indoor pool during the same period, and had no identified contact with individuals linked to the outdoor pool. With the use of subgenotyping based on analysis of three mini- and microsatellite loci, MS1, TP14, and GP15, we could identify two sources of exposure. One subtype was associated with the outdoor pool and another with the indoor pool. These data demonstrate that the use of mini- and microsatellite loci as markers for molecular fingerprinting ofC. parvumisolates are valuable in the epidemiological investigation of outbreaks.

SUMMARYSerological responses toCryptosporidium-specific antigens (15/17 and 27 kDa) were compared among populations in four areas of the Czech Republic that use drinking water from clearly defined sources: (1) wells in a fractured sandstone aquifer, (2) riverbank infiltration, or (3) two different filtered and chlorinated surface waters. Among persons surveyed in the area with riverbank-infiltration water, 33% had a strong serological response to the 15/17-kDa antigen group whereas, in the other three areas, over 72% of persons had a strong response. These response differences suggest thatCryptosporidiumexposures and infection were lower in the area with bank infiltration. The large percentage of the study population with a strong serological response to both antigens suggests high levels of previous infections that may have resulted in protective immunity for cryptosporidiosis. This may be one reason why no waterborne cryptosporidiosis outbreaks and few cases of cryptosporidiosis have been reported in the Czech Republic.

SUMMARYBy conducting a case-control study in two university hospitals, we explored the association between modifiable risk behaviours and diarrhoea. Children aged Cryptosporidiumspp. Four hundred cases and controls were enrolled between 2007 and 2009. The strongest independent risk factors for diarrhoea were: presence of another household member with diarrhoea [matched odds ratio (mOR) 4·9, 95% CI 2·8–8·4] in the week preceding the survey, introduction to a new kind of food (mOR 3, 95% CI 1·7–5·4), and the child being cared for outside home (mOR 2·6, 95% CI 1·3–5·2). While these risk factors are not identifiable, in some age groups more easily modifiable risk factors were identified including: having no soap for handwashing (mOR 6·3, 95% CI 1·2–33·9) for children aged 7–12 months, and pacifier use (mOR 1·9, 95% CI 1·0–3·5) in children aged 0–6 months. In total, the findings of this study suggest that community-based interventions to improve practices related to sanitation and hygiene, handwashing and food could be utilized to reduce the burden of diarrhoea in Egyptian children aged

SUMMARYThis study describes the epidemiology and symptoms in 271 cryptosporidiosis patients in Stockholm County, Sweden. Species/genotypes were determined by polymerase chain reaction–restriction fragment-length polymorphism (PCR–RFLP) of theCryptosporidiumoocyst wall protein (COWP) and 18S rRNA genes. Species wereC. parvum(n=111),C. hominis(n=65),C. meleagridis(n=11),C. felis(n=2),Cryptosporidiumchipmunk genotype 1 (n=2), and a recently described species,C. viatorum(n=2). Analysis of the Gp60 gene revealed fiveC. hominisallele families (Ia, Ib, Id, Ie, If), and fourC. parvumallele families (IIa, IIc, IId, IIe). MostC. parvumcases (51%) were infected in Sweden, as opposed toC. hominiscases (26%). Clinical manifestations differed slightly by species. Diarrhoea lasted longer inC. parvumcases compared toC. hominisandC. meleagridiscases. At follow-up 25–36 months after disease onset, 15% of the patients still reported intermittent diarrhoea. In four outbreaks and 13 family clusters, a single subtype was identified, indicating a common infection source, which emphasizes the value of genotyping for epidemiological investigations.

SUMMARYThis study provides a comprehensive epidemio-clinical picture of sporadic, domestically acquired cases of amoebiasis, cryptosporidiosis and giardiasis in one Canadian community based on patient symptom, outcome and exposure data from an enhanced surveillance system. It yields valuable data for estimating the burden of those diseases including the proportion of bloody diarrhoea, hospitalization, and disease duration. Age differences were observed by incidence rate and for some clinical information and exposures to risk factors. For each of the three diseases, the animal/environment-to-person route was the most common possible main transmission route according to the exposure reported, whereas the person-to-person route was the least common. Exposure was higher for the 10–24 years age group of giardiasis cases for swimming in recreational waters (79%) and attending a barbeque (50%). Therefore, comparisons between groups of cases or extrapolation of results when estimating the burden of illness should be adjusted for age.