An outbreak of waterborne cryptosporidiosis associated with a public water supply in the UK

Infectious Diseases Associated with Hydrometeorological Hazards in Europe: Disaster Risk Reduction in the Context of the Climate Crisis and the Ongoing COVID-19 Pandemic

Hydrometeorological hazards comprise a wide range of events, mainly floods, storms, droughts, and temperature extremes. Floods account for the majority of the related disasters in both developed and developing countries. Flooding alters the natural balance of the environment and frequently establish a favorable habitat for pathogens and vectors to thrive. Diseases caused by pathogens that require vehicle transmission from host to host (waterborne) or a host/vector as part of their life cycle (vector-borne) are those most likely to be affected by flooding. Considering the most notable recent destructive floods events of July 2021 that affected several Central Europe countries, we conducted a systematic literature review in order to identify documented sporadic cases and outbreaks of infectious diseases in humans in Europe, where hydrometeorological hazards, mainly floods, were thought to have been involved. The occurrence of water-, rodent-, and vector-borne diseases in several European countries is highlighted, as flooding and the harsh post-flood conditions favor their emergence and transmission. In this context, strategies for prevention and management of infectious disease outbreaks in flood-prone and flood-affected areas are also proposed and comprise pre- and post-flood prevention measures, pre- and post-outbreak prevention measures, as well as mitigation actions when an infectious disease outbreak finally occurs. Emphasis is also placed on the collision of floods, flood-related infectious disease outbreaks, and the evolving COVID-19 pandemic, which may result in unprecedented multi-hazard conditions and requires a multi-hazard approach for the effective disaster management and risk reduction.

Extreme Precipitation, Public Health Emergencies, and Safe Drinking Water in the USA

PURPOSE OF REVIEW

This review examines the effectiveness of drinking water regulations to inform public health during extreme precipitation events. This paper estimates the vulnerability of specific populations to flooding in their public water system, reviews the literature linking precipitation to waterborne outbreaks, examines the role that Safe Drinking Water Act and Public Notification (PN) Rule have in public health emergencies, and reviews the effectiveness of the PN Rule during the 2017 Hurricane Maria in Puerto Rico.

RECENT FINDINGS

Public water systems in large metropolitan areas have substantial portions of their customer base at risk for a waterborne outbreak during a flooding event. The PN Rule are ambiguous for who is responsible for declaring a "waterborne emergency" following a natural disaster like Hurricane Maria. Revisions to the current PN Rule that mandate public notification and water quality sampling during extreme precipitation events are necessary to ensure the public is aware of their drinking water quality following these events.

Validation of Quantitative Microbial Risk Assessment Using Epidemiological Data from Outbreaks of Waterborne Gastrointestinal Disease

The assumptions underlying quantitative microbial risk assessment (QMRA) are simple and biologically plausible, but QMRA predictions have never been validated for many pathogens. The objective of this study was to validate QMRA predictions against epidemiological measurements from outbreaks of waterborne gastrointestinal disease. I screened 2,000 papers and identified 12 outbreaks with the necessary data: disease rates measured using epidemiological methods and pathogen concentrations measured in the source water. Eight of the 12 outbreaks were caused by Cryptosporidium, three by Giardia, and one by norovirus. Disease rates varied from 5.5 × 10^-6 to 1.1 × 10^-2 cases/person-day, and reported pathogen concentrations varied from 1.2 × 10^-4 to 8.6 × 10² per liter. I used these concentrations with single-hit dose-response models for all three pathogens to conduct QMRA, producing both point and interval predictions of disease rates for each outbreak. Comparison of QMRA predictions to epidemiological measurements showed good agreement; interval predictions contained measured disease rates for 9 of 12 outbreaks, with point predictions off by factors of 1.0-120 (median = 4.8). Furthermore, 11 outbreaks occurred at mean doses of less than 1 pathogen per exposure. Measured disease rates for these outbreaks were clearly consistent with a single-hit model, and not with a "two-hit" threshold model. These results demonstrate the validity of QMRA for predicting disease rates due to Cryptosporidium and Giardia.

Analysis of adoption rates for Needs Driven versus Value Driven innovation water technologies

This paper analyzes six case studies of new water technology innovations in the last three decades and investigates the differences in timelines for moving through the various stages of water technology commercialization. The concept of two different types of innovation was explored: Crisis/Needs Driven and Value Driven. It was found that the case studies that mapped to the Crisis/Needs Driven innovation moved relatively quickly compared to Value Driven innovations and in most cases involved new entrants. New entrants refer to new companies or start-ups that have recently entered the water technology market. The case studies, which could be mapped to Value Driven innovation, had a slower rate of technology diffusion, and they involved a combination of existing companies as well as new entrants. PRACTITIONER POINTS: The paper identifies two key types of innovation: Crisis/Needs Driven and Value Driven. Legislation was observed to be a key driver for the adoption of new technology innovation in the water sector. The Crisis/Needs driven innovations studied were observed to diffuse through the Water Technology Diffusion model at up to twice the pace of Value driven innovation. Crisis/Needs driven innovation typically involves disruptive innovation offered by new entrants, whereas with Value driven innovation, the solutions are provided by both existing companies as well as new entrants. It is also observed that in most cases a technology that is adopted in order to meet a crisis or need in the market is more expensive at the outset compared with incumbent solutions. While value driven adoption has a slower cycle for adoption, it presents a lower risk as it is less dependent on external factors and timing of implementation of regulations or the occurrence of some public health related or environmental crisis.

Proventriculitis Associated with Cryptosporidium baileyi in a Snowy Owl (Bubo scandiacus) and Its Epidemiological Investigation

We describe an unusual case of proventriculitis associated with Cryptosporidium baileyi in a 7-wk-old snowy owl (Bubo scandiacus) chick kept at a zoo. Necropsy of this animal revealed diffuse mucosal thickening of the proventriculus. Subsequent histopathological examinations of the proventriculus showed marked ductal epithelial hyperplasia with intestinal metaplasia and severe inflammatory cell infiltration in the lamina propria and submucosa. These lesions were associated with numerous periodic-acid-Schiff-positive cryptosporidia-like protozoan parasites. Moreover, oocysts found within the lamina propria had a noticeably thicker wall and displayed Ziehl-Neelsen-positive test results. PCR sequencing analyses of the 18S rDNA, actin, and 70 kDa heat shock protein gene loci identified the protozoan to be C. baileyi, of which two novel sets of primers were designed for use with formalin-fixed paraffin-embedded tissue. An epidemiological survey was carried out at the zoo to investigate the source of infection, but all owl species surveyed proved negative for cryptosporidiosis. It is most likely that small animal vectors such as wild birds or rodents were responsible for this particular lethal case. This is the first report of C. baileyi associated with proventriculitis and also the first report of cryptosporidiosis in a raptor species in Asia.

Pseudo-Second-Order Calcium-Mediated Cryptosporidium parvum Oocyst Attachment to Environmental Biofilms

Cryptosporidium parvum oocysts are able to infect a wide range of mammals, including humans, via fecal-oral transmission. The remobilization of biofilm-associated C. parvum oocysts back into the water column by biofilm sloughing or bulk erosion poses a threat to public health and may be responsible for waterborne outbreaks; thus, the investigation of C. parvum attachment mechanisms to biofilms, particularly the physical and chemical factors controlling oocyst attachment to biofilms, is essential to predict the behavior of oocysts in the environment. In our study, biofilms were grown in rotating annular bioreactors using prefiltered stream water (0.2-μm retention) and rock biofilms (6-μm retention) until the mean biofilm thickness reached steady state. Oocyst deposition followed a calcium-mediated pseudo-second-order kinetic model. Kinetic parameters (i.e., initial oocyst deposition rate constant and total number of oocysts adhered to biofilms at equilibrium) from the model were then used to evaluate the impact of water conductivity on the attachment of oocysts to biofilms. Oocyst deposition was independent of solution ionic strength; instead, the presence of calcium enhanced oocyst attachment, as demonstrated by deposition tests. Calcium was identified as the predominant factor that bridges the carboxylic functional groups on biofilm and oocyst surfaces to cause attachment. The pseudo-second-order kinetic profile fit all experimental conditions, regardless of water chemistry and/or lighting conditions.

IMPORTANCE

The cation bridging model in our study provides new insights into the impact of calcium on the attachment of C. parvum oocysts to environmental biofilms. The kinetic parameters derived from the model could be further analyzed to elucidate the behavior of oocysts in commonly encountered complex aquatic systems, which will enable future innovations in parasite detection and treatment technologies to protect public health.

Untangling the Impacts of Climate Change on Waterborne Diseases: a Systematic Review of Relationships between Diarrheal Diseases and Temperature, Rainfall, Flooding, and Drought

Global climate change is expected to affect waterborne enteric diseases, yet to date there has been no comprehensive, systematic review of the epidemiological literature examining the relationship between meteorological conditions and diarrheal diseases. We searched PubMed, Embase, Web of Science, and the Cochrane Collection for studies describing the relationship between diarrheal diseases and four meteorological conditions that are expected to increase with climate change: ambient temperature, heavy rainfall, drought, and flooding. We synthesized key areas of agreement and evaluated the biological plausibility of these findings, drawing from a diverse, multidisciplinary evidence base. We identified 141 articles that met our inclusion criteria. Key areas of agreement include a positive association between ambient temperature and diarrheal diseases, with the exception of viral diarrhea and an increase in diarrheal disease following heavy rainfall and flooding events. Insufficient evidence was available to evaluate the effects of drought on diarrhea. There is evidence to support the biological plausibility of these associations, but publication bias is an ongoing concern. Future research evaluating whether interventions, such as improved water and sanitation access, modify risk would further our understanding of the potential impacts of climate change on diarrheal diseases and aid in the prioritization of adaptation measures.

Effects of climate changes on skin diseases

Global climate is changing at an extraordinary rate. Climate change (CC) can be caused by several factors including variations in solar radiation, oceanic processes, and also human activities. The degree of this change and its impact on ecological, social, and economical systems have become important matters of debate worldwide, representing CC as one of the greatest challenges of the modern age. Moreover, studies based on observations and predictive models show how CC could affect human health. On the other hand, only a few studies focus on how this change may affect human skin. However, the skin is the most exposed organ to environment; therefore, it is not surprising that cutaneous diseases are inclined to have a high sensitivity to climate. The current review focuses on the effects of CC on skin diseases showing the numerous factors that are contributing to modify the incidence, clinical pattern and natural course of some dermatoses.

Climate variability, weather and enteric disease incidence in New Zealand: time series analysis

BACKGROUND

Evaluating the influence of climate variability on enteric disease incidence may improve our ability to predict how climate change may affect these diseases.

OBJECTIVES

To examine the associations between regional climate variability and enteric disease incidence in New Zealand.

METHODS

Associations between monthly climate and enteric diseases (campylobacteriosis, salmonellosis, cryptosporidiosis, giardiasis) were investigated using Seasonal Auto Regressive Integrated Moving Average (SARIMA) models.

RESULTS

No climatic factors were significantly associated with campylobacteriosis and giardiasis, with similar predictive power for univariate and multivariate models. Cryptosporidiosis was positively associated with average temperature of the previous month (β =  0.130, SE =  0.060, p <0.01) and inversely related to the Southern Oscillation Index (SOI) two months previously (β =  -0.008, SE =  0.004, p <0.05). By contrast, salmonellosis was positively associated with temperature (β  = 0.110, SE = 0.020, p<0.001) of the current month and SOI of the current (β  = 0.005, SE = 0.002, p<0.050) and previous month (β  = 0.005, SE = 0.002, p<0.05). Forecasting accuracy of the multivariate models for cryptosporidiosis and salmonellosis were significantly higher.

CONCLUSIONS

Although spatial heterogeneity in the observed patterns could not be assessed, these results suggest that temporally lagged relationships between climate variables and national communicable disease incidence data can contribute to disease prediction models and early warning systems.

Waterborne cryptosporidiosis: current status

In the past ten years Cryptosporidium oocysts have been shown to be common contaminants of water, causing at least 19 waterborne outbreaks of cryptosporidiosis which have affected more than 427 000 individuals. Recommended methods for oocyst isolation and enumeration are time-consuming and inefficient and experts state that the absence of Cryptosporidium oocysts in drinking water can never be guaranteed. In the UK alone, a National Research Programme costing pound3 million has been undertaken. Here, Huw Smith and Joan Rose review the current status of knowledge and identify approaches taken by UK and USA Government regulatory bodies in order to reduce the likelihood of waterborne transmission.

Overview of the ability of different treatment methods for liquid and solid manure to inactivate pathogens

The use of manure as a fertilizer in agriculture includes the risk of spreading pathogenic infectious agents to the environment, to animals and humans. The treatment of manure can help avoid or reduce these risks. Even if the treatment is dominated by economic considerations such as biogas production, ammonia stripping or phosphorous precipitation, the hygienic aspect should be kept in mind. Otherwise, new infection chains may be established by the use of insufficiently treated manure by-products such as fertilizers still containing infective pathogens. Treatment plants should use a concept according to HACCP principles that includes hazard analysis, risk assessment, the determination of process relevant CCPs and the validation of the process by determining the hygienizing efficiency using representative test organisms as well as microbial end product supervision. Treatment methods can be divided into physical, chemical and microbiological treatment, sometimes used in combination. For economical reasons, only composting or anaerobic treatment (biogas) or, to a minor extent, aerobic thermophilic stabilization (ATS) are used as routine preventive measures on a farm level. In cases of outbreaks of notifiable diseases both physical and chemical treatment of manure can lead to reliable disinfected/pasteurised end products which can be used in agriculture without long-lasting risks for soil fertility or the environment.

Detection of Cryptosporidium spp. and Giardia duodenalis in surface water: a health risk for humans and animals

The objective of the present study was to determine the degree of contamination by Cryptosporidium spp. and Giardia duodenalis in a river basin in a livestock farming area in Galicia (NW, Spain). Water samples (50 l) were collected at 22 points in the main basin (including 5 recreational areas), and at the source and mouth of the 3 most important rivers and at the mouth of a smaller, secondary river. Faecal samples were collected from dairy cattle selected at random from 18 herds farmed in the area. A total of 139 neonatal calves, 480 heifers and 697 cows were sampled. The prevalence, intensity of infection and the risk associated with the spread of infection by both enteropathogens were determined. Water and faecal samples were collected in spring, summer, autumn and winter of 2007. The species and genotypes of these parasites present in the water samples were identified. In both water and faecal samples, more parasitic stages were collected in spring and summer than in autumn and winter. In spring, Cryptosporidium spp. oocysts were detected in 33 (9.4%) cows from 13 (72.2%) herds, and G. duodenalis cysts were detected in 56 (16.0%) cows from 15 farms (83.3%); the intensity of infection ranged from 5 to 7895 G. duodenalis cysts per gram of faeces. Infective stages of Cryptosporidium spp. and G. duodenalis were also detected in respectively 26 (89.6%) and 27 (93.1%) water samples, in spring. The mean concentrations of parasites ranged from 2 to 1200 Cryptosporidium spp. oocysts per litre and from 2 to 400 G. duodenalis cysts per litre. Cryptosporidium parvum, C. andersoni, C. hominis and assemblages A-I, A-II, E of G. duodenalis were detected. The presence of both protozoans must be monitored in cattle, in sources of water used for recreational purposes and in artificial waterways used by farmers (water channels, animal drinking water and drainage systems).

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.

Published case studies of waterborne disease outbreaks--evidence of a recurrent threat

Residents of affluent nations are remarkably lucky to have high-quality, safe drinking water supplies that most residents of modem cities enjoy, particularly when considered in contrast to the toll of death and misery that unsafe drinking water causes for most of the world's population. Some may presume that drinking-water disease outbreaks are a thing of the past, but complacency can easily arise. A review of drinking water outbreaks in developed countries over the past 3 decades reveals some of the reasons why drinking water outbreaks keep occurring when society clearly has the means to prevent them. Prevention of future outbreaks does not demand perfection, only a commitment to learn from past mistakes and to act on what has been learned.

Detection of a small number of Cryptosporidium parvum oocysts by sugar flotation and sugar centrifugation methods

Detection rates from the samples including a small number of Cryptosporidium parvum oocysts were compared between the sugar flotation and the sugar centrifugal flotation methods. As the results, the oocysts were detected from 70 and 80 of 100 samples including 6.0x10(2) and 1.0x10(3) oocysts per 1 ml by the flotation method, respectively, whereas from 52 and 53 of the same samples by the centrifugal flotation method. Therefore, it was considered that the flotation method is the most suitable method for the detection from samples including a small number of Cryptosporidium oocysts. It is also suggested that results of the sugar flotation method were reliable for samples including more than 1.0x10(3) oocysts/ml.

Infectious diseases of severe weather-related and flood-related natural disasters

PURPOSE OF REVIEW

The present review will focus on some of the possible infectious disease consequences of disastrous natural phenomena and severe weather, with a particular emphasis on infections associated with floods and the destruction of infrastructure.

RECENT FINDINGS

The risk of infectious diseases after weather or flood-related natural disasters is often specific to the event itself and is dependent on a number of factors, including the endemicity of specific pathogens in the affected region before the disaster, the type of disaster itself, the impact of the disaster on water and sanitation systems, the availability of shelter, the congregating of displaced persons, the functionality of the surviving public health infrastructure, the availability of healthcare services, and the rapidity, extent, and sustainability of the response after the disaster. Weather events and floods may also impact disease vectors and animal hosts in a complex system.

SUMMARY

Weather or flood-related natural disasters may be associated with an increased risk of soft tissue, respiratory, diarrheal, and vector-borne infectious diseases among survivors and responders.

Genotyping of single Cryptosporidium oocysts in sewage by semi-nested PCR and direct sequencing

This study describes an approach for genotyping individual Cryptosporidium oocysts obtained from sewage. We isolated single immunofluorescent assay (IFA)-stained Cryptosporidium oocysts from sewage concentrate using glass capillary pipettes and inverted epifluorescence microscopy. Each isolated Cryptosporidium oocyst was analyzed by semi-nested PCR for the 18S rRNA gene and direct sequencing of the PCR products. A total of 74 of 107 oocysts isolated from sewage were genotyped successfully. Of the 74 genotyped isolates, 51% (38 oocysts) were identified as C. parvum genotype 1, 4% (3 oocysts) of C. parvum VF383 human isolates, 20% (15 oocysts) of C. parvum genotype 2, 14% (10 oocysts) of C. meleagridis, 7% (5 oocysts) of C. sp. Pig 1, 3% (2 oocysts) of C. sp PG1-26 pig isolates and 1% (1 oocyst) of C. parvum CPM1 isolated from mouse. The results of this study demonstrate that 18S rRNA-based semi-nested PCR and direct sequencing can be used to characterize individual Cryptosporidium oocysts and also to reveal the distribution of Cryptosporidium genotypes in environmental waters.

Soil macropores and compaction control the leaching potential of Escherichia coli O157:H7

The influence of soil structure in controlling leaching of Escherichia coli O157:H7 through soil was investigated under controlled conditions using both intact and repacked soil cores. Leaching rates of E. coli O157:H7 decreased with increasing dry bulk density and were significantly increased by the presence of earthworm (Lumbricus terrestris) burrows in repacked cores. For intact cores, the percentage of E. coli O157:H7 that leached through replicate cores within 72 h varied from 0.01% to 24%. In contrast, the dry bulk densities of intact cores varied only slightly and were not significantly correlated with leaching. Differences in the numbers of E. coli O157:H7 cells in the leachates were not related to variability in the flow volumes, which were relatively constant as a result of the experimental design, but were strongly correlated with the variations in concentrations of E. coli O157:H7 in the leachates. Relatively small variations in the internal structure of soil cores can therefore significantly affect the pathway that cells can take through soil. Factors such as compaction and the occurrence of pores providing preferential flow are prime determinants in the degree of leaching of E. coli O157:H7 through soil.

Evaluation of Cryptosporidium parvum oocyst recovery efficiencies from various filtration cartridges by electrochemiluminescence assays

AIMS

To evaluate four types of filtration cartridges for their capacities, efficiency for capture and release of Cryptosporidium parvum oocysts for detection.

METHODS AND RESULTS

Filtration cartridges included in this evaluation were IDEXX Filta-Max, Gelman Envirochek HV, Corning CrypTest, and Filterite Sigma+. Various dosages of C. parvum oocysts were spiked into water samples with a wide range of turbidity (10-50 NTU). Electrochemiluminescence assays were employed to enumerate viable or total number of C. parvum oocysts in these eluates. Among the cartridges tested, Filta-Max consistently showed higher oocyst recovery efficiency, especially with large volume, highly turbid water samples.

CONCLUSIONS

Filta-Max filter is the best performer because of its higher oocyst recovery efficiency.

SIGNIFICANCE AND IMPACT OF THE STUDY

The overall sensitivities of various C. parvum oocyst detection assays in water samples can be improved if highly efficient oocyst recovery filtration cartridges such as Filta-Max are incorporated in sample preparation.

Survival of Cryptosporidium parvum oocysts after prolonged exposure to still natural mineral waters

The survival kinetics of purified Cryptosporidium parvum oocysts of both human and ovine origin, immersed in four still natural mineral waters (total dissolved salts ranging from 91 mg/liter to 430 mg/liter) and reverse osmosis water was assessed by inclusion or exclusion of the fluorogenic vital dyes 4',6-diamidino-2-phenylindole and propidium iodide over a 12-week period. Semipermeable chambers were used to contain the oocysts while immersed in each mineral water type, permitting both intimate interactions between oocysts and matrices and straightforward sampling for viability assessments. The viability of both oocyst types, assessed at weekly intervals, remained unaltered after 12 weeks at 4 degrees C, whereas a progressive decline in the viability of both oocyst isolates was observed when immersed in mineral waters at 20 degrees C. At 20 degrees C, approximately 30% of oocysts remained viable after 12 weeks incubation. Here, temperature was the major factor that adversely affected oocyst survival, although higher mineral content was also proportionally and significantly associated with this increased oocyst inactivation. The prolonged survival of oocysts at 4 degrees C in our studies indicates that they could survive for prolonged periods of time in U.K. groundwaters (average temperature approximately 10 degrees C) and thus represent a potential public health hazard if contamination of mineral water sources by viable oocysts were to occur.

Climate change and waterborne and vector-borne disease

This paper considers the potential impact on human health from waterborne and vector-borne infections. It concentrates on the impact of two possible changes to climate; increased frequency of heavy rainfall events, with associated flooding and increased temperature. Flooding is associated with increased risk of infection in developing nations but not in the West unless water sources are compromised. There have been numerous reported of outbreaks that followed flooding that led to contamination of underground sources of drinking water. Heavy rainfall also leads to deterioration in the quality of surface waters that could adversely affect the health of those engaged in recreational water contact. It is also concluded that there may be an increase in the number of cyanobacterial blooms because of a combination of increased nutrient concentrations and water temperature. It is considered unlikely that climate change will lead to an increase in disease linked to mains drinking water, although private supplies would be at risk from increased heavy rainfall events. Although increased temperature could lead to climatic conditions favourable to increases in certain vector-borne diseases such as malaria, the infrastructure in the UK would prevent the indigenous spread of malaria.

Identification of bacterial spores using statistical analysis of Fourier transform infrared photoacoustic spectroscopy data

Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) has been applied for the first time to the identification and speciation of bacterial spores. A total of forty specimens representing five strains of Bacillus spores (Bacillus subtilis ATCC 49760, Bacillus atrophaeus ATCC 49337, Bacillus subtilis 6051, Bacillus thuringiensis subsp. kurstaki, and Bacillus globigii Dugway) were analyzed. Spores were deposited, with minimal preparation, into the photoacoustic sample cup and their spectra recorded. Principal component analysis (PCA), classification and regression trees (CART), and Mahalanobis distance calculations were used on this spectral library to develop algorithms for step-wise classification at three levels: (1) bacterial/nonbacterial, (2) membership within the spore library, and (3) bacterial strain. Internal cross-validation studies on library spectra yielded classification success rates of 87% or better at each of these three levels. Analysis of fifteen blind samples, which included five samples of spores already in the spectral library, two samples of closely related Bacillus globigii 01 spores not in the library, and eight samples of nonbacterial materials, yielded 100% accuracy in distinguishing among bacterial/nonbacterial samples, membership in the library, and bacterial strains within the library.

Occurrence of Salmonella spp and Cryptosporidium spp in a French coastal watershed: relationship with fecal indicators

Cryptosporidium and Salmonella are pathogenic microorganisms that can cause severe gastrointestinal illness in humans. Because these organisms are potentially transmitted through natural waters, this study was carried out to estimate the concentrations of both pathogens in a French coastal watershed and to determine the relationships with fecal indicators. Water samples from nine wastewater treatment plants and eight rivers were analyzed. Although both pathogens and indicators are released from sewage effluents, no clear correlation was found between the two enteric pathogens nor between a given pathogen and fecal indicators. These results suggest that fecal indicators do not adequately indicate the presence of Cryptosporidium and Salmonella in natural waters and that pathogens and indicators may have different behaviors in the aquatic environment.

Commercial assay for detection of Giardia lamblia and Cryptosporidium parvum antigens in human fecal specimens by rapid solid-phase qualitative immunochromatography

The ImmunoCard STAT! Cryptosporidium/Giardia rapid assay (Meridian Bioscience, Inc.) is a solid-phase qualitative immunochromatographic assay that detects and distinguishes between Giardia lamblia and Cryptosporidium parvum in aqueous extracts of human fecal specimens (fresh, frozen, unfixed, or fixed in 5 or 10% formalin or sodium acetate-acetic acid-formalin). By using specific antibodies, antigens specific for these organisms are isolated and immobilized on a substrate. After the addition of appropriate reagents, a positive test is detected visually by the presence of a gray-black color bar (regardless of the intensity) next to the organism name printed on the test device. A control is included in the device. Steps include tube preparation (buffer, patient specimen, conjugates A and B), testing (addition of sample onto the test device), and visual reading (total time, 12 min). Test performance was evaluated with known positive and negative stool specimens (170 specimens positive for Giardia and 231 specimens negative for Giardia) (85 specimens positive for Cryptosporidium and 316 specimens negative for Cryptosporidium); they were tested with trichrome, iron-hematoxylin, or modified acid-fast stains or the Meridian Bioscience, Inc., Giardia/Cryptosporidium Merifluor combination reagent; specimens with discrepant results were retested by using the Merifluor combination reagent. On the basis of the results of the reference methods, the sensitivities, specificities, and positive and negative predictive values were as follows: for G. lamblia, 93.5, 100, 100, and 95.5%, respectively; for C. parvum, 98.8, 100, 100, and 99.7%, respectively. False-negative results for G. lamblia were obtained with specimens with low parasite numbers (n = 7) or specimens containing trophozoites only (n = 3); one specimen with a false-negative result contained numerous cysts. The one specimen false negative for C. parvum was confirmed to be positive by immunofluorescence. No cross-reactivity was seen with 10 different protozoa (152 challenges), nine different helminths (35 challenges), or human cells (4 challenges) found in fecal specimens. This rapid test system may be very beneficial in the absence of trained microscopists; however, for patients who remain symptomatic after a negative result, the ova and parasite examination and special stains for other coccidia and the microsporidia should always remain options.

Efficacy of UV irradiation in inactivating Cryptosporidium parvum oocysts

To evaluate the effectiveness of UV irradiation in inactivating Cryptosporidium parvum oocysts, the animal infectivities and excystation abilities of oocysts that had been exposed to various UV doses were determined. Infectivity decreased exponentially as the UV dose increased, and the required dose for a 2-log(10) reduction in infectivity (99% inactivation) was approximately 1.0 mWs/cm(2) at 20 degrees C. However, C. parvum oocysts exhibited high resistance to UV irradiation, requiring an extremely high dose of 230 mWs/cm(2) for a 2-log(10) reduction in excystation, which was used to assess viability. Moreover, the excystation ability exhibited only slight decreases at UV doses below 100 mWs/cm(2). Thus, UV treatment resulted in oocysts that were able to excyst but not infect. The effects of temperature and UV intensity on the UV dose requirement were also studied. The results showed that for every 10 degrees C reduction in water temperature, the increase in the UV irradiation dose required for a 2-log(10) reduction in infectivity was only 7%, and for every 10-fold increase in intensity, the dose increase was only 8%. In addition, the potential of oocysts to recover infectivity and to repair UV-induced injury (pyrimidine dimers) in DNA by photoreactivation and dark repair was investigated. There was no recovery in infectivity following treatment by fluorescent-light irradiation or storage in darkness. In contrast, UV-induced pyrimidine dimers in the DNA were apparently repaired by both photoreactivation and dark repair, as determined by endonuclease-sensitive site assay. However, the recovery rate was different in each process. Given these results, the effects of UV irradiation on C. parvum oocysts as determined by animal infectivity can conclusively be considered irreversible.

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

Cryptosporidium parvum and Giardia lamblia are important agents of waterborne diarrheal illness worldwide. While giardiasis is routinely diagnosed in Russia with a chemical staining technique, data on the prevalence of cryptosporidiosis are scarce. Monitoring of the respective parasites in water supplies in Russia is very limited. A health survey conducted in the city of Cherepovets and three other cities in the European part of Russia using enzyme-linked immunosorbent assays (ELISA) demonstrated that 6.9% of diarrheal patients tested had C. parvum antigens in their fecal samples; 9.4% had G. lamblia antigens. A survey of occurrence of these parasites in water supplies in Cherepovets and seven other cities demonstrated that source and finished water samples from several of these cities were contaminated with either C. parvum oocysts or G. lamblia cysts. The surveys were not designed to assess associations between presence or concentrations of C. parvum and G. lamblia in water and related gastrointestinal diseases in exposed populations. Rather, the goals were to demonstrate the presence of disinfection-resistant protozoan parasites in untreated and treated waters, and the importance of these pathogens as causative agents of diarrheal illnesses in a number of Russian cities.

Evaluation of ColorPAC Giardia/Cryptosporidium rapid assay and ProSpecT Giardia/Cryptosporidium microplate assay for detection of Giardia and Cryptosporidium in fecal specimens

Detection of Giardia and Cryptosporidium in clinical stool specimens using the ColorPAC and ProSpecT enzyme immunoassays revealed 98.7% agreement for Giardia detection and 98.1% agreement for Cryptosporidium detection. Sensitivities were uniformly 100%. The specificities of the ColorPAC immunoassay for Giardia and Cryptosporidium detection were 100 and 99.5%, respectively, and those for the ProSpecT assay were 98.4 and 98.6%, respectively. The false-positive reactions with the ProSpecT assay occurred with specimens that were grossly bloody.

Cryptosporidium infection in Bedouin infants assessed by prospective evaluation of anticryptosporidial antibodies and stool examination

An enzyme-linked immunosorbent assay system using oocyst lysate as antigen was used to detect serum- specific antibody responses to Cryptosporidium parvum between 1989 and 1994 in consecutive sera obtained at birth, and at the age of 6, 12, and 23 months, from 52 infants living in a Bedouin town located in the south of Israel. The serologic tests revealed high levels of immunoglobulin G anti-Cryptosporidium at birth that dropped significantly by the age of 6 months and then rose continuously to a geometric mean titer of 481 at age 23 months. The serum immunoglobulin M Cryptosporidium antibodies rose continuously from nearly undetectable levels at birth to a geometric mean titer of 471 (157-fold increase) at age 23 months. All the subjects already showed at 6 months a significant rise in immunoglobulin M. A significant rise in immunoglobulin A titers was detected in 48% and 91% of subjects at 6 and 23 months, respectively. By monthly surveillance, microscopy using the modified Ziehl-Neelsen method and confirmed by indirect immunofluorescence assay detected Cryptosporidium antigens in only 11% at age 6 months and 48% at age 23 months. The extent of exposure to Cryptosporidium immediately after birth as detected by serology is much higher than that predicted by frequent prospective assessment of stool samples.

Epidemiology of Cryptosporidium: transmission, detection and identification

There are 10 valid species of Cryptosporidium and perhaps other cryptic species hidden under the umbrella of Cryptosporidium parvum. The oocyst stage is of primary importance for the dispersal, survival, and infectivity of the parasite and is of major importance for detection and identification. Because most oocysts measure 4-6 microm, appear nearly spherical, and have obscure internal structures, there are few or no morphometric features to differentiate species and in vitro cultivation does not provide differential data as for bacteria. Consequently, we rely on a combination of data from three tools: morphometrics, molecular techniques, and host specificity. Of 152 species of mammals reported to be infected with C. parvum or an indistinguishable organism, very few oocysts have ever been examined using more than one of these tools. This paper reviews the valid species of Cryptosporidium, their hosts and morphometrics; the reported hosts for the human pathogen, C. parvum; the mechanisms of transmission; the drinking water, recreational water, and food-borne outbreaks resulting from infection with C. parvum; and the microscopic, immunological, and molecular methods used to detect and identify species and genotypes.

Detection of Giardia lamblia, Entamoeba histolytica/Entamoeba dispar, and Cryptosporidium parvum antigens in human fecal specimens using the triage parasite panel enzyme immunoassay

The Triage parasite panel (BIOSITE Diagnostics, San Diego, Calif.) is a new qualitative enzyme immunoassay (EIA) panel for the detection of Giardia lamblia, Entamoeba histolytica/E. dispar, and Cryptosporidium parvum in fresh or fresh, frozen, unfixed human fecal specimens. By using specific antibodies, antigens specific for these organisms are captured and immobilized on a membrane. Panel performance was evaluated with known positive and negative stool specimens (a total of 444 specimens) that were tested by the standard ova and parasite (O&P) examination as the "gold standard," including staining with both trichrome and modified acid-fast stains. Specimens with discrepant results between the reference and Triage methods were retested by a different method, either EIA or immunofluorescence. A number of samples with discrepant results with the Triage device were confirmed to be true positives. After resolution of discrepant results, the number of positive specimens and the sensitivity and specificity results were as follows: for G. lamblia, 170, 95.9%, and 97.4%, respectively; for E. histolytica/E. dispar, 99, 96.0%, and 99.1%, respectively; and for C. parvum, 60, 98.3%, and 99.7%, respectively. There was no cross-reactivity with other parasites found in stool specimens, including eight different protozoa (128 challenges) and three different helminths (83 challenges). The ability to perform the complete O&P examination should remain an option for those patients with negative parasite panel results but who are still symptomatic.

Epidemiology, microbiology, and risk assessment of waterborne pathogens including Cryptosporidium

Cryptosporidium is one of a suite of relatively recently emerging pathogens of concern in drinking water. Based on human dose-response tests, guidelines for exposure yielding defined levels of endemic risk have been developed. This risk assessment procedure is grounded in the process used for chemical risk assessment. From outbreak data, critical concentrations in water that may lead to epidemic levels have been postulated. Development of these levels will be discussed. Validation of the information using outbreak reports from the 1993 Milwaukee incident can be made. Use of this approach must be tempered by the existence of substantial waterborne cases in the absence of detectable oocyst levels as in the Las Vegas outbreak, and (apparent) high levels of oocysts without (apparent) significant health effects as in the case of the (at the time of this writing) ongoing incident in Sydney, Australia.

Cross-sectional study of faecal shedding of Giardia duodenalis and Cryptosporidium parvum among packstock in the Sierra Nevada Range

Faecal specimens from 305 horses and mules used as packstock at one of 17 commercial or governmental (National Park Service, US Forest Service) operations were examined for Giardia duodenalis and Cryptosporidium parvum using immunofluorescent microscopy. Fourteen packstock (4.6%) were shedding G. duodenalis cysts, with herd-level prevalences ranging 0-22%. Number of packstock in the corral, size of corral and density of packstock in the corral were associated with the odds of shedding G. duodenalis cysts. None of the horses had detectable C. parvum oocysts. Assuming a sensitivity of at least 43% and a specificity of 100% for our assay, the estimated maximum true prevalence of shedding of C. parvum for packstock would be < or = 2.3% of the population. These data suggest that faecal dispersal of C. parvum on back country watersheds is unlikely with packstock.

Detection of Giardia lamblia and Cryptosporidium parvum antigens in human fecal specimens using the ColorPAC combination rapid solid-phase qualitative immunochromatographic assay

The ColorPAC Giardia/Cryptosporidium (Becton Dickinson) is a solid-phase qualitative immunochromatographic assay that detects and distinguishes between Giardia lamblia and Cryptosporidium parvum in human stool. Agreement between the Alexon-Trend ProSpecT Giardia Rapid EIA and the ColorPAC assay was 166 of 172 (96.5%). Agreement between the Alexon-Trend ProSpecT Cryptosporidium Rapid EIA and the ColorPAC assay was 169 of 171 (98.8%). No cross-reactions were seen with other parasites or human cells.

Cryptosporidiosis in the immunocompromised: weighing up the risk

Cryptosporidiosis has been increasingly recognised as a cause of diarrhoeal illness in both immunocompetent and immunocompromised people. Massive outbreaks have been linked to municipal drinking water supplies in North America and Europe, but so far none have been reported in Australia. There is evidence that modes of transmission other than drinking water are more important. There can be no guarantee that infective Cryptosporidium oocysts will not contaminate an Australian water supply. Therefore, a permanent "boil water" warning may be warranted on medical advice in severely immunocompromised people, for whom cryptosporidiosis could be persistent and life threatening.

Cryptosporidia and microsporidia--waterborne diseases in the immunocompromised host

Cryptosporidia and microsporidia are emerging parasitic pathogens in immunocompetent and immunocompromised individuals. Cryptosporidium infects several wild and domestic animals that excrete oocysts into the environment and contaminated water represents the major source of infection for humans. Waterborne transmission of Cryptosporidium is a major risk for humans and appropriate measures have to be taken to protect immunocompetent and immunocompromised individuals to become infected. For microsporidia, the sources and ways of transmission are not well documented. Although several animal hosts have been identified recently, the relevant reservoirs of human microsporidia are still unknown. Also, the routes of spreading are unknown. Is microsporidiosis a zoonotic disease that will be transmitted through close contact with infected animals or is contaminated surface water responsible for transmission and represents a relevant reservoir? This review is designed to give information on these two emerging intestinal parasites in a format that will be useful to clinical microbiologists, physicians interested in infectious diseases, and public health personnel.

Microbiological safety of drinking water: United States and global perspectives

Waterborne disease statistics only begin to estimate the global burden of infectious diseases from contaminated drinking water. Diarrheal disease is dramatically underreported and etiologies seldom diagnosed. This review examines available data on waterborne disease incidence both in the United States and globally together with its limitations. The waterborne route of transmission is examined for bacterial, protozoal, and viral pathogens that either are frequently associated with drinking water (e.g., Shigella spp.), or for which there is strong evidence implicating the waterborne route of transmission (e.g., Leptospira spp.). In addition, crucial areas of research are discussed, including risks from selection of treatment-resistant pathogens, importance of environmental reservoirs, and new methodologies for pathogen-specific monitoring. To accurately assess risks from waterborne disease, it is necessary to understand pathogen distribution and survival strategies within water distribution systems and to apply methodologies that can detect not only the presence, but also the viability and infectivity of the pathogen.

Microbiological safety of drinking water: United States and global perspectives

Waterborne disease statistics only begin to estimate the global burden of infectious diseases from contaminated drinking water. Diarrheal disease is dramatically underreported and etiologies seldom diagnosed. This review examines available data on waterborne disease incidence both in the United States and globally together with its limitations. The waterborne route of transmission is examined for bacterial, protozoal, and viral pathogens that either are frequently associated with drinking water (e.g., Shigella spp.), or for which there is strong evidence implicating the waterborne route of transmission (e.g., Leptospira spp.). In addition, crucial areas of research are discussed, including risks from selection of treatment-resistant pathogens, importance of environmental reservoirs, and new methodologies for pathogen-specific monitoring. To accurately assess risks from waterborne disease, it is necessary to understand pathogen distribution and survival strategies within water distribution systems and to apply methodologies that can detect not only the presence, but also the viability and infectivity of the pathogen.

Prevalence of and associated risk factors for shedding Cryptosporidium parvum oocysts and Giardia cysts within feral pig populations in California

Populations of feral pigs (Sus scrofa) may serve as an environmental reservoir of Cryptosporidium parvum oocysts and Giardia sp. cysts for source water. We conducted a cross-sectional study to determine the prevalence of and associated demographic and environmental risk factors for the shedding of C. parvum oocysts and Giardia sp. cysts. Feral pigs were either live-trapped or dispatched from 10 populations located along the coastal mountains of western California, and fecal samples were obtained for immunofluorescence detection of C. parvum oocysts and Giardia sp. cysts. We found that 12 (5.4%) and 17 (7.6%) of 221 feral pigs were shedding C. parvum oocysts and Giardia sp. cysts, respectively. The pig's sex and body condition and the presence of cattle were not associated with the probability of the shedding of C. parvum oocysts. However, younger pigs (< or = 8 months) and pigs from high-density populations (> 2.0 feral pigs/km2) were significantly more likely to shed oocysts compared to older pigs (> 8 months) and pigs from low-density populations (< or = 1.9 feral pigs/km2). In contrast, none of these demographic and environmental variables were associated with the probability of the shedding of Giardia sp. cysts among feral pigs. These results suggest that given the propensity for feral pigs to focus their activity in riparian areas, feral pigs may serve as a source of protozoal contamination for surface water.

The presence of Cryptosporidium oocysts in stools of clinically diarrhoeic and normal nonhuman primates in Kenya

A total of 114 nonhuman primates comprising 51 vervet monkeys (Cercopithecus aethiops) and 63 olive baboons (Papio anubis) were examined for Cryptosporidium oocysts using the modified Kinyoun's acid-fast staining technique. About 51.7% (59/114) of all the specimens examined, representing 78.4% (40/51) of the vervet monkeys and 30.1% (19/63) of the olive baboons were positive. Bright red, refractile Cryptosporidium oocysts were observed in the stained faecal smears against a blue background. Up to 4/6 (66.7%) of the diarrhoeic vervets and 2/3 (66.7%) baboons, respectively, were positive while the rest were negative. To the best of our knowledge, this report is the first on cryptosporidiosis in old world nonhuman primates in Kenya and probably the first report of the infection in olive baboons. Given the high frequency of oocysts in diarrhoeal specimens, the parasite may have been associated with clinical diarrhoea in the sampled animals. Cryptosporidium, which has been reported in humans in Kenya, is also suspected to occur in livestock. Its isolation from clinically ill, normal colony-borne and newly caught feral nonhuman primates has significant implications for both public health and animal agriculture in Kenya.

Evaluation of nine immunoassay kits (enzyme immunoassay and direct fluorescence) for detection of Giardia lamblia and Cryptosporidium parvum in human fecal specimens

It is well known that Giardia lamblia and Cryptosporidium parvum can cause severe symptoms in humans, particularly those who are immunologically compromised. Immunoassay procedures offer both increased sensitivity and specificity compared to conventional staining methods. These reagents are also helpful when screening large numbers of patients, particularly in an outbreak situation or when screening patients with minimal symptoms. The data obtained by using 9 diagnostic kits were compared: direct fluorescent-antibody assay (DFA) kits (TechLab Giardia/Crypto IF kit, TechLab Crypto IF kit, and Meridian Merifluor Cryptosporidium/Giardia) and enzyme immunoassay (EIA) kits (Alexon ProSpecT Giardia EZ Microplate Assay, Alexon ProSpecT Cryptosporidium Microplate Assay, Cambridge Giardia lamblia Antigen Microwell ELISA, Meridian Premier Giardia lamblia, Meridian Premier Cryptosporidium, TechLab Giardia CELISA, Trend Giardia lamblia EIA). The test with the Meridian Merifluor Cryptosporidium/Giardia kit was used as the reference method. In various combinations, 60 specimens positive for Giardia, 60 specimens positive for Cryptosporidium, 40 specimens positive for a Giardia-Cryptosporidium mix, and 50 negative fecal specimens were tested. Different species (nine protozoa, three coccidia, one microsporidium, five nematodes, three cestodes, and one trematode) were included in the negative specimens. The sensitivity of EIA for Giardia ranged from 94% (Alexon) to 99% (Trend and Cambridge); the specificity was 100% with all EIA kits tested. The sensitivity of EIA for Cryptosporidium ranged from 98% (Alexon) to 99% (Meridian Premier); specificities were 100%. All DFA results were in agreement, with 100% sensitivity and specificity; however, the TechLab reagents resulted in fluorescence intensity that was generally one level below that seen with the reagents used in the reference method. In addition to sensitivity and specificity, factors such as cost, simplicity, ease of interpretation of results (color, intensity of fluorescence), equipment, available personnel, and number of tests ordered are also important considerations prior to kit selection.