Contamination of water supplies with Cryptosporidium parvum and Giardia lamblia and diarrheal illness in selected Russian cities

Cryptosporidium and agriculture: A review

Cryptosporidiosis is a significant contributor to global foodborne and waterborne disease burden. It is a widespread cause of diarrheal diseases that affect humans and animals worldwide. Agricultural environments can become a source of contamination with Cryptosporidium species through faecal material derived from humans and animals. This review aims to report the main findings of scientific research on Cryptosporidium species related to various agricultural sectors, and highlights the risks of cryptosporidiosis in agricultural production, the contamination sources, the importance of animal production in transmission, and the role of farmed animals as hosts of the parasites. Agricultural contamination sources can cause water pollution in groundwater and different surface waters used for drinking, recreational purposes, and irrigation. The application of contaminated manure, faecal sludge management, and irrigation with inadequately treated water are the main concerns associated with foodborne and waterborne cryptosporidiosis related to agricultural activities. The review emphasizes the public health implications of agriculture concerning the transmission risk of Cryptosporidium parasites and the urgent need for a new concept in the agriculture sector. Furthermore, the findings of this review provide valuable information for developing appropriate measures and monitoring strategies to minimize the risk of infection.

Weather, water quality and infectious gastrointestinal illness in two Inuit communities in Nunatsiavut, Canada: potential implications for climate change

Climate change is expected to cause changes in precipitation quantity, intensity, frequency and duration, which will subsequently alter environmental conditions and might increase the risk of waterborne disease. The objective of this study was to describe the seasonality of and explore associations between weather, water quality and occurrence of infectious gastrointestinal illnesses (IGI) in two communities in Nunatsiavut, Canada. Weather data were obtained from meteorological stations in Nain (2005-2008) and Rigolet (2008). Free-chlorine residual levels in drinking water were extracted from municipal records (2005-2008). Raw surface water was tested weekly for total coliform and E. coli counts. Daily counts of IGI-related clinic visits were obtained from health clinic registries (2005-2008). Analysis of weather and health variables included seasonal-trend decomposition procedures based on Loess. Multivariable zero-inflated Poisson regression was used to examine potential associations between weather events (considering 0-4 week lag periods) and IGI-related clinic visits. In Nain, water volume input (rainfall + snowmelt) peaked in spring and summer and was positively associated with levels of raw water bacteriological variables. The number of IGI-related clinic visits peaked in the summer and fall months. Significant positive associations were observed between high levels of water volume input 2 and 4 weeks prior, and IGI-related clinic visits (P < 0.05). This study is the first to systematically gather, analyse and compare baseline data on weather, water quality and health in Nunatsiavut, and illustrates the need for high quality temporal baseline information to allow for detection of future impacts of climate change on regional Inuit human and environmental health.

Clinical characteristics and etiology of travelers' diarrhea among Korean travelers visiting South-East Asia

The morbidity of travelers' diarrhea (TD) is still high. This study examined the incidence of common pathogens and characteristics of TD among Korean travelers who visited South-East Asian countries. We performed a prospective study involving 479 Korean travelers with diarrheal disease from February 2009 to April 2009 and stool samples were examined and questionnaire surveys were done after arrival. Enterotoxigenic Escherichia coli (ETEC) was found in 36.0% of TD cases, as were the following: Enteroaggregative Escherichia coli (EAEC) in 27.0%, Vibrio parahaemolyticus in 13.1%, and Norovirus in 11.5%. The detected rate of classic TD was higher in men (P = 0.007), in patients who had a shorter duration trip (P = 0.023) and in patients who drank more than 1 liter of water per day (P = 0.037). Positive stool culture rates were higher in men (P = 0.005), in hospitalized patients (P = 0.013). and in those who consumed impure water or raw foods (P = 0.033). A higher severity of disease corresponded to a significantly higher culture positivity rate (P = 0.029). We should consider the possibility of other pathogens in addition to ETEC in patients with TD who visit South-East Asia. Travelers need to educate about risk factors associated with TD.

Microsporidiosis and Cryptosporidiosis in HIV/AIDS Patients in St. Petersburg, Russia: Serological identification of microsporidia and Cryptosporidium parvum in sera samples from HIV/AIDS patients

To determine seroprevalence of the opportunistic organisms Cryptosporidium parvum and microsporidia (Encephalitozoon cuniculi, E. intestinalis, E. hellem, and Enterocytozoon bieneusi) in Russian HIV/AIDS patients, we evaluated 46 sera from HIV/AIDS patients from the S.P. Botkin Clinical Infectious Diseases Hospital, St. Petersburg, Russia. Five (10.9%) sera were seropositive for E. cuniculi and 19 (41.3%) were positive for C. parvum by ELISA. By IFAT, 6 (13.0%) sera were seropositive for E. bieneusi, 4 (8.7%) for E. intestinalis, and 9 (19.6%) for E. hellem. This study is the first report to estimate the prevalence of infection with Cryptosporidium and microsporidia among Russian HIV/AIDS patients.

Seasonality of Cryptosporidium oocyst detection in surface waters of Meru, Kenya as determined by two isolation methods followed by PCR

Meru, Kenya has watersheds which are shared by wildlife, humans and domesticated animals. These surface waters can be contaminated by the waterborne pathogen Cryptosporidium. To quantify the seasonality and prevalence of Cryptosporidium in Meru regional surface waters, we used a calcium carbonate flocculation (CCF) and sucrose floatation method, and a filtration and immunomagnetic bead separation method, each of which used PCR for Cryptosporidium detection and genotyping. Monthly water samples were collected from January through June in 2003 and 2004, bracketing two April-May rainy seasons. We detected significant seasonality with 8 of 9 positive samples from May and June (p<0.0014), which followed peak rainy season precipitation and includes some of the subsequent dry season. Six of 9 positive samples revealed C. parvum, and 3 contained C. andersoni. None contained C. hominis. Our results indicate that Meru surface waters are Cryptosporidium-contaminated at the end of rainy seasons, consistent with the timing of human infections reported by others from East Africa and contrasting with the onset of rainy season peak incidence reported from West Africa.

Access to water in the countries of the former Soviet Union

BACKGROUND

During the Soviet period, authorities in the USSR invested heavily in collective farming and modernization of living conditions in rural areas. However, many problems remained, including poor access to many basic amenities such as water. Since then, the situation is likely to have changed; economic decline has coincided with migration and widening social inequalities, potentially increasing disparities within and between countries.

AIM

To examine access to water and sanitation and its determinants in urban and rural areas of eight former Soviet countries.

METHODS

A series of nationally representative surveys in Armenia, Belarus, Georgia, Moldova, Kazakhstan, Kyrgyzstan, Russia and Ukraine was undertaken in 2001, covering 18,428 individuals (aged 18+ years).

RESULTS

The percentage of respondents living in rural areas varied between 27 and 59% among countries. There are wide urban-rural differences in access to amenities. Even in urban areas, only about 90% of respondents had access to cold running water in their home (60% in Kyrgyzstan). In rural areas, less than one-third had cold running water in their homes (44% in Russia, under 10% in Kyrgyzstan and Moldova). Between one-third and one-half of rural respondents in some countries (such as Belarus, Kazakhstan and Moldova) obtained their water from wells and similar sources. Access to hot running water inside the homes was an exception in rural households, reflecting the lack of modern heating methods in villages. Similarly, indoor access to toilets is common in urban areas but rare in rural areas. Access to all amenities was better in Russia compared with elsewhere in the region. Indoor access to cold water was significantly more common among rural residents living in apartments, and in settlements served by asphalt roads rather than dirt roads. People with more assets or income and living with other people were significantly more likely to have water on tap. In addition, people who had moved in more recently were more likely to have an indoor water supply.

CONCLUSIONS

This was the largest single study of its kind undertaken in this region, and demonstrates that a significant number of people living in rural parts of the former Soviet Union do not have indoor access to running water and sanitation. There are significant variations among countries, with the worse situation in central Asia and the Caucasus, and the best situation in Russia. Access to water strongly correlates with socio-economic characteristics. These findings suggest a need for sustained investment in rebuilding basic infrastructure in the region, and monitoring the impact of living conditions on health.

Human cryptosporidiosis: an update with special emphasis on the situation in Europe

The genus Cryptosporidium consists of different species and genotypes which infect a wide range of hosts, including humans. The parasite is ubiquitous and lack of differentiation between the species and strains has made it difficult to track down sources of human and animal infections. Genetic analysis of strains and isolates has led to the redescription of Cryptosporidium with special consideration of the host specificity and possible ways of transmission to humans. Infection with the small oocysts usually occurs directly by faecal-oral transmission, water- or food-borne. In Europe water from different sources is frequently contaminated with oocysts. Generally, humans are most frequently infected with C. hominis in an anthroponotic cycle (especially in cases of infections imported from highly endemic (sub-) tropical regions) and the animal genotype (type II) of C. parvum in a zoonotic cycle which seems to play a major role in autochthonous infections in Switzerland, the UK and probably other European countries. Other species (such as C. felis or the avian species C. meleagridis and C. baileyi) and genotypes are rare in humans and mostly restricted to immunocompromised individuals who are highly susceptible to serious opportunistic cryptosporidial infections.

Exposures to drinking water chlorination by-products in a Russian city

Exposures to water disinfection by-products (DBPs) via ingestion of drinking water, and dermal absorption and inhalation during showering/bathing were assessed in the city of Cherepovets, Russia, which uses heavy chlorination to disinfect organic-rich surface water. Concentrations of DBPs (mean +/- standard deviation) in tap water were the following: total trihalomethanes (THMs) 205 +/- 70 micrograms/l, five haloacetic acids (HAAs) 150 +/- 30 micrograms/l, and 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (mutagen X or MX) 160 +/- 50 ng/l. Concentrations of THMs and HAAs exceeded the corresponding US standards by a factor of 2.5, while MX concentrations were the highest ever reported. The mutagenic activity of tap water extracts in the Salmonella TA-100 assay was 14,900 net revertants/l. Concentrations of chloroform in breathing zone air in bathrooms during showering were 330 +/- 260 micrograms/m3, shower room air at an industrial plant 2,600 +/- 1,100 micrograms/m3, and bedrooms of local residents 2 +/- 2 micrograms/m3. The mean concentration of chloroform was 3.2 micrograms/m3 in exhaled air samples collected before showering and 110 micrograms/m3 after showering. Data on water ingestion and water use practices in the general population and for pregnant women were collected using questionnaires and diaries. Due to concerns over microbiological safety of water, average daily consumption of non-boiled tap water in pregnant women was only 0.01 l/day, while consumption of boiled tap water was 0.81 l/day. This resulted in low ingestion exposures to volatile THMs. Inhalation and dermal absorption determined total exposures to these compounds. HAAs and MX persist in boiled water and drinks resulting in high ingestion exposures. Several brands of inexpensive home water filters were tested for removal of these compounds. To demonstrate a method of exposure reduction in a sensitive subpopulation, the most efficient filters were given to a group of pregnant women. These women and a control group of pregnant women without filters maintained water ingestion diaries for two weeks. The use of home filters resulted in reduction of exposures to HAAs by a factor of three and a greater reduction in exposures to MX.

Giardia intestinalis

PURPOSE OF REVIEW

Giardia intestinalis (syn. duodenalis or lamblia) is one of the most common intestinal parasites in the world, with an estimated 2.8 x 10(6) infections per year in humans, and it contributes to diarrhea and nutritional deficiencies in children in developing regions. The wide prevalence of Giardia and its unique place in evolutionary biology have led to ongoing research.

RECENT FINDINGS

Research into the basic biology of Giardia has highlighted some of its unique properties as an 'early-branching' eukaryote. Although Giardia do not contain mitochondria, they have developed pathways to perform some mitochondrial functions. Investigations into encystation and excystation have identified new gene products that are important in cyst wall formation, and signal transduction events that occur during excystation. The ability to transfect Giardia stably will lead to an improved understanding of its development and metabolism. Molecular typing of G. intestinalis isolates indicates that most animal parasites are not associated with human infection. Insights into immunology have helped define the role of IL-6 in the early control of murine giardiasis, and the contributions of IgA in controlling infection. Further studies of giardiasis in poorly nourished children in developing regions supports an important contributing role of Giardia in stunting and cognitive impairment. Finally, new diagnostic assays using antigen detection are being evaluated and a new agent, nitazoxanide, has been approved in the USA for the treatment of giardiasis and cryptosporidiosis in children.

SUMMARY

Research into the biology of Giardia should increase knowledge about protist differentiation and will complement studies in other biological systems. Continued study of the role of Giardia in chronic diarrhea and malnutrition in developing regions will help focus strategies to improve childhood growth and nutrition.