Risk Of Giardiasis Research Articles

Investigating the relationship between extreme weather and cryptosporidiosis and giardiasis in Colorado: A multi-decade study using distributed-lag nonlinear models

Environmentally-mediated protozoan diseases like cryptosporidiosis and giardiasis are likely to be highly impacted by extreme weather, as climate-related conditions like temperature and precipitation have been linked to their survival, distribution, and overall transmission success. Our aim was to investigate the relationship between extreme temperature and precipitation and cryptosporidiosis and giardiasis infection using monthly weather data and case reports from Colorado counties over a twenty-one year period. Data on reportable diseases and weather among Colorado counties were collected using the Colorado Electronic Disease Reporting System (CEDRS) and the Daily Surface Weather and Climatological Summaries (Daymet) Version 3 dataset, respectively. We used a conditional Poisson distributed-lag nonlinear modeling approach to estimate the lagged association (between 0 and 12-months) between relative temperature and precipitation extremes and the risk of cryptosporidiosis and giardiasis infection in Colorado counties between 1997 and 2017, relative to the risk found at average values of temperature and precipitation for a given county and month. We found distinctly different patterns in the associations between temperature extremes and cryptosporidiosis, versus temperature extremes and giardiasis. When maximum or minimum temperatures were high (90th percentile) or very high (95th percentile), we found a significant increase in cryptosporidiosis risk, but a significant decrease in giardiasis risk, relative to risk at the county and calendar-month mean. Conversely, we found very similar relationships between precipitation extremes and both cryptosporidiosis and giardiasis, which highlighted the prominent role of long-term (>8 months) lags. Our study presents novel insights on the influence that extreme temperature and precipitation can have on parasitic disease transmission in real-world settings. Additionally, we present preliminary evidence that the standard lag periods that are typically used in epidemiological studies to assess the impacts of extreme weather on cryptosporidiosis and giardiasis may not be capturing the entire relevant period.

Projected local rain events due to climate change and the impacts on waterborne diseases in Vancouver, British Columbia, Canada

BackgroundClimate change is increasing the number and intensity of extreme weather events in many parts of the world. Precipitation extremes have been linked to both outbreaks and sporadic cases of waterborne illness. We have previously shown a link between heavy rain and turbidity to population-level risk of sporadic cryptosporidiosis and giardiasis in a major Canadian urban population. The risk increased with 30 or more dry days in the 60 days preceding the week of extreme rain. The goal of this study was to investigate the change in cryptosporidiosis and giardiasis risk due to climate change, primarily change in extreme precipitation.MethodsCases of cryptosporidiosis and giardiasis were extracted from a reportable disease system (1997–2009). We used distributed lag non-linear Poisson regression models and projections of the exposure-outcome relationship to estimate future illness (2020–2099). The climate projections are derived from twelve statistically downscaled regional climate models. Relative Concentration Pathway 8.5 was used to project precipitation derived from daily gridded weather observation data (~ 6 × 10 km resolution) covering the central of three adjacent watersheds serving metropolitan Vancouver for the 2020s, 2040s, 2060s and 2080s.ResultsPrecipitation is predicted to steadily increase in these watersheds during the wet season (Oct. -Mar.) and decrease in other parts of the year up through the 2080s. More weeks with extreme rain (>90th percentile) are expected. These weeks are predicted to increase the annual rates of cryptosporidiosis and giardiasis by approximately 16% by the 2080s corresponding to an increase of 55–136 additional cases per year depending upon the climate model used. The predicted increase in the number of waterborne illness cases are during the wet months. The range in future projections compared to historical monthly case counts typically differed by 10–20% across climate models but the direction of change was consistent for all models.DiscussionIf new water filtration measures had not been implemented in our study area in 2010–2015, the risk of cryptosporidiosis and giardiasis would have been expected to increase with climate change, particularly precipitation changes. In addition to the predicted increase in the frequency and intensity of extreme precipitation events, the frequency and length of wet and dry spells could also affect the risk of waterborne diseases as we observed in the historical period. These findings add to the growing evidence regarding the need to prepare water systems to manage and become resilient to climate change-related health risks.

Social determinants associated with Giardia duodenalis infection in southern Côte d'Ivoire.

The purpose of this investigation was to analyze the association between different social determinants of health at the local scale and Giardia duodenalis infection in diverse settlements in southern Côte d'Ivoire. Stool samples from 306 individuals aged 1-16years were collected from six rural villages and a small town. Five variables were categorized to classify the increasing risk levels of acquiring intestinal parasites. Giardia prevalences (%) and odds ratios (ORs) were evaluated. Correlation and regression analyses were conducted to determine the correlation coefficients and to propose predictive models based on social determinants to forecast the risk of giardiasis. The overall observed prevalence of Giardia was 21.6%. When the analysis was conducted at the local level, the percentage of infected people varied from a minimum of 12.7 up to 36.4%. A significant association (p < 0.001) was found between the selected social determinants and G. duodenalis prevalence in the different localities. Correlation and regression analyses allowed us to describe two predictive models to estimate the OR of Giardia transmission. This study helps to clarify the possible impact of different social determinants of health on the risk of giardiasis at the local scale. Both predictive models could be suitable in order to assess the likelihood of the transmission of intestinal parasitic infection in developing countries.

Forest Fragmentation and Risk of Giardiasis in New York State

In the United States, giardiasis is endemic in northern and northeastern states, but its ecology and epidemiology remain elusive. The underlying physical landscape may play a role in shaping points of contact between humans, animals, and Giardia cysts. This study examined 11 years of surveillance data in New York State to measure the relationship between forest fragmentation and the incidence of giardiasis. Adjusted Poisson models showed that increasing points of contact between forested land and developed land, as measured by their shared edges [incident rate ratio (IRR) = 1.003; P < 0.001] and by the perimeter length of forested patches (IRR = 1.31; P = 0.01), were associated with higher incidence of giardiasis cases, whereas increasing forest density was associated with a lower incidence (IRR = 0.97; P < 0.001). These associations were independent of both temperature and surface water area. While these results are only suggestive due to the county-level aggregated data, the findings do identify a potentially important signal in the landscape epidemiology of giardiasis and highlight the need for better, more targeted, field studies on individual water sources for household consumption, inter-species contact in ecotones, surface water contamination, and human giardiasis cases.

Risk of giardiasis associated with water supply in an endemic context

Consumption of untreated, inadequately treated or simply chlorinated water has been the source of a number of giardiasis epidemics. The aim of this study was to verify if water supply is associated with giardiasis in an endemic context. We conducted a case-control study that included 139 cases and 417 control subjects. To assess risk associated to water consumption, we calculated odds ratios (OR) using “source of water” and “presence and type of filtration” as criteria. A logistic regression model was used to control other risk factors. In children aged 1 – 13, the only significant risk factor was the consumption of at-risk tap water (i.e., filtered or unfiltered surface water or unfiltered shallow well water; OR = 6.13). In people aged 14 – 64, the consumption of this water was not a risk factor for the disease. The divergence in results between age groups could be explained by acquired immunity.

Risk of giardiasis in Aucklanders: a case—control study

Background: Giardia is one of the leading protozoal causes of human gastrointestinal illnesses. It is prevalent in both developed and developing countries. Currently, giardiasis is the most commonly notified waterborne disease in New Zealand. The aim of the study was to identify potentially modifiable risk factors for Giardia infection in the adult population in Auckland. Methods: This case-control study involved 183 Giardia-positive cases and 336 randomly selected controls, aged between 15 and 64 years. Exposure information was collected retrospectively over the telephone for the 21 days preceding the date of onset of symptoms. Both univariate and multiple logistic regression analyses were carried out. Results: The majority of cases were in the 25–44-year age group and in the New Zealand European ethnic group. Housewives and nursing mothers were at significant risk of the disease (odds ratio (OR)=2.06; 95% CI=1.4–3.74), as were the occupational groups exposed to human wastes (OR=4.04, 95% CI=1.85–8.85). Consumption of drinking water from New Zealand supplies other than metropolitan mains supplies (OR=2.11, 95% CI= 1.36–3.27) or from sources outside New Zealand (OR=7.97, 95 % CI=4.20–15.12) represented a significantly higher risk, as did traveling (OR=7.57, 95% CI=4.03–14.23) and swimming in pools or fresh water at least once a week (OR=2.04, 95% CI= 1.33-3.12). Conclusions: The study identified potentially modifiable risk factors for Giardia infection. These findings should be investigated further in different groups and settings to ensure better protection of the public health.

Nappy handling and risk of giardiasis

We did a case-control study to identify modifiable risk factors for giardiasis in people aged 15-64 years living in Auckland, New Zealand. 183 patients with stool-positive Giardia spp referred to community laboratories were compared with 336 age-matched controls identified randomly from the Auckland telephone book. Exposure information for the previous 3 weeks was obtained retrospectively by telephone. Nappy changing was associated with a four-fold increased risk of infection after controlling for other confounders. We conclude that children wearing nappies could be an important source of giardia infection in the community.

Risk of giardiasis from consumption of wilderness water in North America: A systematic review of epidemiologic data

Objectives: A meta-analytic study was conducted to test the hypothesis that consumption of water from North American backcountry sources poses a statistically significant risk for acquisition of giardiasis. Methods: The biomedical literature was surveyed by accessing Medline, and identified studies were supplemented with references in current reviews, published dissertations, and prior communications with state health departments. Studies were classified by methodologic design and subjected to predetermined inclusion criteria. Odds ratios with 95% confidence intervals, chi-squares, and P-values for epidemiologic surveys were either computed from raw data or abstracted directly from the included studies. Results: Of 104 articles identified in the initial screening, nine met the inclusion criteria. Neither of two case reports met the criteria of the Centers for Disease Control and Prevention (CDC) for waterborne disease outbreak. Two prospective studies were identified, but neither showed a significant association. Of four case-control studies providing data, three reported an odds ratio of greater than one. Conclusions: Published reports of confirmed giardiasis among outdoor recreationists clearly demonstrate a high incidence among this population. However, the evidence for an association between drinking backcountry water and acquiring giardiasis is minimal. Education efforts aimed at outdoor recreationists should place more emphasis on handwashing than on water purification. Further studies should attempt to separate the specific risk factor of drinking water from backcountry sources from other behaviors among this group that may contribute to the risk.

Giardiasis Risk From an Unfiltered, Protected Surface Water Source

This article describes the efforts of water utility personnel to determine whether the level of endemic giardiasis observed in their service area could be attributed to the surface water supply, which is chloraminated but not filtered. Comparison of epidemiological data for the county in which the utility is located with data from another county that used conventionally treated water showed similar incidence rates, partitioning into risk categories, and age distributions for giardiasis. There was no correlation between the location of a giardiasis case and disinfection contact time within the unfiltered water's distribution system.