Family outbreak of cryptosporidiosis

Understanding Giardia infections among rural communities using the one health approach

The epidemiology of giardiasis in rural villages in Peninsular Malaysia was examined in the context of the One Health triad that encompasses humans, animals and environment (i.e. river water). A cross-sectional study was carried out among five rural communities in Malaysia to determine the prevalence of Giardia duodenalis in humans, animals and river water. Fecal samples collected from humans and animals were examined by light microscopy. Water was sampled from the rivers adjacent to the target communities and investigated for the occurrence of Giardia cysts. The isolated cysts were further genotyped targeting the glutamate dehydrogenase and triosephosphate isomerase genes. The overall prevalence of G. duodenalis was 6.7% (18/269) and 4.7% (8/169) among humans and animals, respectively. Giardia cysts (mean concentration range: 0.10-5.97 cysts/L) were also found in adjacent rivers at four out of the five villages examined. At Kemensah and Kuala Pangsun, Giardia cysts were isolated from humans [rate: 3.7% each (of 54 each)], animals [rates: 6.3% (of 62) and 11.3% (of 16), respectively] and river water [average concentration of 9 samples each: 0.83±0.81 and 5.97±7.00, respectively]. For both villages at Pos Piah and Paya Lebar, 12.2% (of 98) and 6.1% (of 33) of collected human samples were infected, respectively whilst none of the collected animals samples in these villages were found to be positive. The river water samples of these two villages were also contaminated (average concentration: 0.20±0.35 (of 9) and 0.10±0.19 (of 3), respectively). In conclusion, Giardia cysts were simultaneously observed in the human-animal-environment (i.e., river water) interfaces in at least two of five studied communities highlighting a vital need to improve understanding on the interplay of transmission dynamics, the role of infected humans and animals in contaminating the water sources and the role of water as a vehicle of disease transmission in these communities. Indeed, this study illustrates the One Health approach which is to recognize that the optimal health of humans are interconnected with the well-being of animals and their environment.

Foodborne protozoan parasites

This report addresses Cryptosporidium, Giardia, Cyclospora, and more briefly, Toxoplasma as the main parasitic protozoa of concern to food production worldwide. Other parasitic protozoa may be spread in food or water but are not considered as great a risk to food manufacture. The protozoan parasites Cryptosporidium, Giardia, and Cyclospora have proven potential to cause waterborne and foodborne disease. Toxoplasma gondii has been considered a risk in specific cases, but humans are not its primary host. Cryptosporidium and Giardia are widespread in the environment, particularly the aquatic environment, and major outbreaks of cryptosporidiosis and giardiasis have occurred as a result of contaminated drinking water. Large outbreaks of waterborne cyclosporiasis have not been identified. Cryptosporidium, Giardia, and Cyclospora have potential significance in the preparation and consumption of fresh produce and in catering practice, in which ready-to-eat foods may be served that have not received heat treatment. None of the three organisms Cryptosporidium, Giardia, and Cyclospora has been shown to be a problem for heat processed food or tap water that has undergone appropriate treatment at a water treatment works. All three are sensitive to standard pasteurisation techniques. Although humans are not a primary host for T. gondii, the potential exists for both waterborne and foodborne toxoplasmosis. Parasitic protozoa do not multiply in foods, but they may survive in or on moist foods for months in cool, damp environments. Their ecology makes control of these parasites difficult. For general control of parasitic protozoa in the food chain, the following steps are necessary: - Follow good hygienic practice in food service and catering industries.- Minimise dissemination of cysts and oocysts in the farming environment and via human waste management.- Include these microorganisms in Hazard Analysis Critical Control Point (HACCP) plans of water suppliers, industries or sectors that use fresh produce, and operations in which contaminated process or ingredient water could end up in the product (e.g., where water supplies may become contaminated).

Inactivation of Cryptosporidium parvum oocyst infectivity by disinfection and sterilization processes

BACKGROUND

Cryptosporidium parvum is a common cause of self-limited gastroenteritis in the normal host but may cause severe disease in immunocompromised persons. Person-to-person transmission has been well documented in households, child care centers, and hospitals. Because contaminated environmental surfaces and medical devices such as endoscopes may play a role in disease transmission, we studied the susceptibility of C parvum to chemical agents commonly used for disinfection and evaluated the efficacy of sterilization processes.

METHODS

Seven disinfectants were studied at their use dilution using a suspension test. Antimicrobial activity was assessed with the use of a cell infectivity assay.

RESULTS

All sterilization processes tested (steam, ethylene oxide, Sterrad 100) inactivated 3 logs or greater of C parvum. The only liquid disinfectant/sterilant able to inactivate greater than 3 logs of C parvum was 6% and 7.5% hydrogen peroxide. Agents that did not completely inactivate C parvum included hydrogen peroxide at lower concentrations or exposure times, peracetic acid, sodium hypochlorite, a phenolic, a quaternary ammonium compound, 2% glutaraldehyde, and ortho-phthalaldehyde.

CONCLUSIONS

Most high-level disinfectants used on endoscopes have limited efficacy against C parvum. However, the infectivity of C parvum on dry surfaces decreases rapidly. Therefore, current cleaning and high-level disinfection guidelines are adequate to prevent nosocomial transmission of C parvum by means of endoscopes.

An outbreak of waterborne cryptosporidiosis in Swindon and Oxfordshire

An outbreak of cryptosporidiosis resulted in 516 cases in Wiltshire and Oxfordshire. The outbreak caused widespread interest and led to an official inquiry. The majority of cases were in children; 8% of cases were admitted to hospital and the median duration of illness was 3 weeks. The geographical distribution of cases matched the distribution of water supplies from three treatment works and cryptosporidium oocysts were found at these works and in the treated water. Attack rates in electoral wards supplied by the three treatment works were significantly higher than in other wards. The cause of the outbreak appeared to be the failure of normal treatment to remove oocysts. Measures at the treatment works reduced the number of oocysts detected in treated water, after which the outbreak came to an end. The conclusion of the investigations was that cryptosporidiosis is a risk of conventionally treated public water supplies.

Cryptosporidiosis in England and Wales: prevalence and clinical and epidemiological features. Public Health Laboratory Service Study Group

In a two year study carried out by 16 public health laboratories in England and Wales 62,421 patients with presumed infective diarrhoea were investigated. Cryptosporidium infection was identified in 2% (1295), ranging from 0.5% to 3.9% among laboratories. The positivity rate for cryptosporidium was highest in 1-4 year olds, and in children cryptosporidium was the second commonest pathogen after campylobacter. Illness was usually limited to abdominal cramps and watery diarrhoea with six motions/24 hours at worst and lasting seven days. Fewer than half the patients reported fever or vomiting. More severe illness with fever, abdominal cramps, vomiting, and watery diarrhoea of frequency greater than five motions in 24 hours was reported by only a tenth of cases but with a significantly increased prevalence in young adult males. One hundred and fifty five patients (12%) probably acquired their infection abroad; 102 (9%) of patients who acquired their infection at home reported drinking raw milk in the month before onset, and 253 (22%) reported close contact with farm animals. Most laboratories experienced sudden infrequent increases in incidence in the community, only one of which was attributed to a recognised outbreak, which occurred in a nursery. Cryptosporidium should be routinely sought by laboratories investigating acute infectious diarrhoea, especially in children; up to a quarter of cases may be directly zoonotic, and the remainder may be due to person to person spread and waterborne infection.

Epidemiological aspects of human cryptosporidiosis

The coccidian protozoan parasiteCryptosporidiumhas been described in many host species since its discovery in the early part of the century, but it remained obscure until the recognition by veterinary workers in the 1970s of its importance as a cause of scours in young livestock animals [1–4].

An outbreak of cryptosporidiosis in a hospital day-care centre

The investigation of an outbreak of cryptosporidiosis in a hospital day-care centre is reported. Twenty-eight (27%) children and one member of the staff were infected. Most of the cases were symptomatic and the major presenting symptom was watery diarrhoea. Shedding of oocysts continued for a mean of 12 days after diarrhoea had subsided and most of the cases were still excreting oocysts when the first follow-up sample was examined. Intermittent shedding or a carrier state were not seen in any of the cases. Giardia intestinalis cysts were detected in 19 children, 7 of whom showing mixed infection with Cryptosporidium sp., but this association was not statistically significant. All cases recovered without specific therapy. No definite proof could be found to demonstrate the source of the outbreak or the route of transmission but some observations suggesting person-to-person transmission are discussed.

Human cryptosporidiosis

Cryptosporidium is an enteric coccidial protozoan recognized in humans in 1976. Since its manifestation as an acquired immunodeficiency syndrome (AIDS)-related infection, new diagnostic techniques have improved recognition of Cryptosporidium oocysts, making apparent its true prevalence in human populations. Cryptosporidium represents 5 to 15% of all enteric pathogens in children in warm climate countries. It is responsible for both endemic and epidemic disease. Day-care center spread is well known, and evidence is strong for person-to-person transmission. The spectrum of illness caused by Cryptosporidium is broad, and while self-limited in immunocompetent individuals, gastrointestinal symptoms can be severe. Asymptomatic infection has been described in population surveys and outbreak investigations. Severe dehydration with malabsorption and failure-to-thrive in children from developing countries has been attributed to this organism. Intractable, incurable diarrhea can be fetal in immunosuppressed adults. Cryptosporidiosis in human immunodeficiency virus-infected individuals is declining in frequency in New York City, possibly reflecting changing sexual behaviors and comparatively low infectivity. No effective treatment for Cryptosporidium has been documented, but clinical trials are in progress.