Using participatory epidemiology to assess factors contributing to common enteric pathogens in Ontario: results from a workshop held at the Ontario Veterinary College, University of Guelph, Ontario.

BACKGROUND: Common enteric pathogens that cause gastrointestinal illness are transmitted to humans through food, water or direct contact. This poses a significant concern to public health as enteric pathogens can cause disease in a large number of people, and cost a substantial amount to treat and prevent. In order to gain a better understanding of the occurrence of enteric disease in Ontario, this study explored public health professionals' perceptions of major contributing factors for common enteric pathogens. METHODS: A case study was conducted as part of a two week training workshop in Participatory Epidemiology held at the Ontario Veterinary College, University of Guelph, in May 2013. Eight semi-structured interviews and four focus groups were conducted with representatives from the Public Health Agency of Canada, the University of Guelph, and three health regions in Southern Ontario. Written notes and pictures captured the qualitative information provided. Results were then analyzed using the mixed methods techniques of triangulation, convergence, and paradox. RESULTS: A total of fifty factors that contribute to enteric disease were identified across all interviews and focus groups. These contributing factors were grouped into key themes (travel, food handling, industry (farm-to-fork), water, geography, demographics, and behaviours) and were categorized as either a risk factor or susceptibility factor. Informants emphasized the complex relationships between the identified factors, and highlighted why these complexities make it difficult to determine where and how a person most likely acquired an enteric pathogen. Workshop participants observed differences in the type and quality of information collected during interviews and focus groups; we hypothesize that this may be attributed to the dynamics between group members (i.e. focus group discussions) as opposed to one-on-one interviews. CONCLUSIONS: The information gathered will serve as a starting point to further explore contributing factors for common enteric pathogens. The identified complexities would be best explored by conducting additional surveillance, as well as interviews and focus groups with a more diverse group of stakeholders. This type of qualitative study can enhance knowledge of enteric pathogen surveillance and contribute to the development of resources and initiatives to holistically address the occurrence of gastrointestinal illness.

Wastewater infrastructure for small cities in an urbanizing world: integrating protection of human health and the environment with resource recovery and food security.

The majority of population growth in developing countries will occur in small cities closely linked to agricultural zones, with poor access to water and sanitation. Wastewater management priorities in these regions will be different from those in larger cities and developed countries. Two wastewater treatment systems in Bolivia, one with an upflow anaerobic sludge blanket (UASB) reactor and polishing ponds, the other with three stabilization ponds, are assessed to determine their resource recovery potential. The UASB reactor produces biogas with 500-650 MJ per day. In six months, both systems discharge wastewater with the same mass of nutrients as fertilizers used to produce crops containing 10-75 days' worth of the recommended food energy intake for each person using the system. Both systems also discharge detectable levels of helminth eggs, Giardia cysts, and Cryptosporidium oocysts, but the UASB reactor system discharges higher concentrations, implying limited reuse potential. From a regional management standpoint, small cities should not expend resources to treat wastewater to levels suitable for discharge into surface waters. Rather, they should focus on removing pathogens to reclaim water and nutrients. Biogas recovery may be a priority that should be subservient to water and nutrient recovery in these settings.

Determining potential indicators of Cryptosporidium oocysts throughout the wastewater treatment process.

Most research on wastewater treatment efficiency compliance focuses on physicochemical and microbial indicators; however, very little emphasis has been placed so far on determining suitable indicator organisms to predict the discharge level of pathogens from treatment plants. In this study, raw wastewater, activated sludge, and the resulting final effluents and biosolids in four municipal wastewater treatment plants (WWTPs A, B, C and D) were seasonally investigated for human-virulent water-borne pathogens Cryptosporidium parvum/hominis and Giardia duodenalis, and microsporidia (e.g. Encephalitozoon hellem, E. intestinalis, and Enterocytozoon bieneusi) between 2008 and 2009. A suite of potential microbial indicators for human-virulent protozoa and microsporidia was also determined. A combination of multiple fluorescent in situ hybridization and immunofluorescent antibody assays were applied to detect Cryptosporidium oocysts, Giardia cysts, and microsporidian spores. Escherichia coli, enterococci and Clostridium perfringens spores were cultivated in selective media. Positive correlations were found between the abundance of enterococci and E. coli and abundance of Cryptosporidium oocysts (r(s) > 0.47, p < 0.01) and Giardia cysts (r(s) > 0.44, p < 0.01) at WWTPs A-D. Cryptosporidium perfringens spores were positively correlated to Cryptosporidium oocysts (r(s) = 0.40, p < 0.01) and Giardia cysts (r(s) = 0.46, p < 0.01). There was a strong positive correlation between abundance of Giardia cysts and that of Cryptosporidium oocysts (r(s) > 0.89, p < 0.01). To sum up, a suite of faecal indicator bacteria can be used as indicators for the presence of Cryptosporidium oocysts and Giardia cysts in these activated-sludge systems (WWTPs A, B and C). Overall, Giardia duodenalis was noted to be the best Cryptosporidium indicator for human health in the community-based influent wastewater and throughout the treatment process.

Land-use change and emerging public health risks in New Zealand: assessing Giardia risks.

Agriculture is key to New Zealand's economy with land-use conversions in response to market forces occurring regularly, like that of recent dairy intensification throughout the country. However, land-use conversion can occasionally result in unexpected and significant consequences for public health that need to be accurately estimated and subsequently managed accordingly. For example, dairy cattle have high Giardia prevalence in New Zealand and identical strains from infected humans and cattle located in the same geographical region have recently been reported. Thus, the high rates of human infections in New Zealand compared to similar socioeconomic countries caused by the waterborne pathogen Giardia are particularly concerning given the increasing dairy cattle populations on the landscape. However, the ability of traditional, evidence-based, epidemiological approaches to detect such causal relationships between land-use and Giardia infections is limited given the many possible indirect links between the two, in turn highlighting the need to develop appropriate risk assessment techniques. As such, the general requirements for and development of risk assessment frameworks to evaluate the likelihood of public health risks from waterborne pathogens are introduced and explored using Giardia in New Zealand as an example. Specifically, the importance of recent advances in Giardia-based knowledge, the incorporation of such data into existing risk assessment frameworks and the influence of remaining research gaps are each discussed for expanding currently available risk assessment tools. Not surprisingly, the availability of appropriate risk assessment tools for agencies responsible for public health and environmental management would ensure the public health risks for Giardia resulting from land-use change could be quantified holistically and strategies subsequently developed through active agency communication to minimise such risks.

Infectivity of Giardia duodenalis Assemblages A and E for the gerbil and axenisation of duodenal trophozoites.

Establishing in vitro cultures of Giardia duodenalis trophozoites from faecal cysts remains very difficult due to poor excystation and bacterial contamination. This study investigated an alternative approach starting from duodenal trophozoites of gerbils that were artificially infected with field isolates from humans (Assemblages A and B) and cattle (Assemblage E and mixed E/A). Gerbil infection was successful for Assemblages A (1/1) and B (1/3) from humans, and for E (1/2) and mixed E/A (6/6) from cattle. Despite the fact that some isolates subsequently failed or were difficult to establish in vitro, several Assemblage A and Assemblage E in vitro trophozoite cultures were successful, however, subsequent cloning required adaptation of the standard TYI-S-33 medium whereby different medium supplements were required for promoting growth. Excess of l-cysteine (2mg/ml) and ascorbic acid (0.2mg/ml) supported cloning of Assemblage A, while l-glutathione (7.8 mg/ml) was required for Assemblage E. This is a first description of in vitro axenisation of Assemblage E trophozoites from cattle.

[The efficacy of ecdystene versus metronidazole in the treatment of lambliasis].

Ecdisten, the drug designed on the basis of the phytoecdisteroid ecdisterone isolated from Rhaponticum carthamoides, was used in the treatment of first diagnosed (primary) and persistent (resistant to traditional lambliacides) lambliasis. A control group received metronidazole. Daily parasitological monitoring of lamblia elimination while treating with ecdisten in a daily dose of 20 mg for 10 days indicated the absence of lamblia in 70% of the patients with primary lambliasis on days 3 to 5; in the remaining 30%, parasitic elimination was accomplished on days 6-7 of treatment. In the patients with persistent lambliasis, the parasites were eliminated in 43.2% of cases on days 4-5 and in 56.6% on days 6-10. Metronidazole just on the second day of therapy caused parasitic elimination in 28.6% of the patients. All the patients were freed from lamblia within 5 days. Improvement occurred more rapidly with ecdisten treatment; immunological normalization was seen when ecdisten was used. Seven-ten-day course of ecdisten is sufficient for the treatment of primary lambliasis; when persistent lambliasis is treated, its course should be prolonged. If required, the course may be repeated, by increasing the daily dose.

Impact of lactoferrin supplementation on growth and prevalence of Giardia colonization in children.

We conducted a randomized, double-blind, placebo-controlled trial comparing supplementation with bovine lactoferrin versus placebo for the prevention of diarrhea in children. Comparison of overall diarrhea incidence and prevalence rates found no significant difference between the 2 groups. However, there was a lower prevalence of colonization with Giardia species and better growth among children in the lactoferrin group.

Water quality monitoring: the basis for watershed management in the Oldman River Basin, Canada.

The Oldman River flows 440 km from its headwaters in south-western Alberta, through mountains, foothills and plains into the South Saskatchewan River. Peak flows occur in May and June. Three major reservoirs, together with more than a dozen other structures, supply water to nine irrigation districts and other water users in the Oldman basin. Human activity in the basin includes forestry, recreation, oil and gas development, and agriculture, including a large number of confined livestock feeding operations. Based on the perception of basin residents that water quality was declining and of human health concern, the Oldman River Basin Water Quality Initiative was formed in 1997 to address the concerns. There was limited factual information, and at the time there was a desire for finger pointing. Results (1998-2002) show that mainstem water quality remains good whereas tributary water quality is more of a challenge. Key variables of concern are nutrients, bacteria and pesticides. Point source discharges are better understood and better regulated, whereas non-point source runoff requires more attention. Recent data on Cryptosporidium and Giardia species are providing benefit for focusing watershed management activities. The water quality data collected is providing a foundation to implement community-supported urban and rural better management practices to improve water quality.

Diarrea aguda: tratamiento nutricional / Acute diarrhea: nutrtional treatment

El tratamiento de la diarrea aguda consistirá básicamente en rehidratación oral si existiera deshidratación, realimentación precoz y excepcionalmente farmacológico. La rehidratación debe durar 4-6 horas, que se prolonga a 8-12 horas si la deshidratación es hipernatrémica, pasando posteriormente a la fase de mantenimiento. Las soluciones de rehidratación oral son las recomendadas, usándose en países en vías de desarrollo la solución de la OMS por las pérdidas importantes de sodio en las heces y soluciones con menor contenido de sodio en los países industrializados al ser las pérdidas de sodio menores. La realimentación debe ser lo mas precoz y equilibrada posible, recoméndandose la lactancia materna si es la forma de alimentación o la fórmula sin diluir si realiza lactancia artificial. No es aconsejable sistemáticamente las fórmulas sin lactosa. El uso de probióticos mejora el cuadro. No se precisa tratamiento farmacológico y los antibióticos sólo están indicados en pacientes inmunodeprimidos, cólera, lactantes menores de 3 meses con coprocultivos bacterianos positivos, enfermedad sistémica, infección por amebas, giardias, clostridium difficile y shigella que permanece sintomática (AU)

Further studies on fecal parasites in antiquity.

This is a continuation study of the survival of antigenic material over the centuries using mummified human remains from the Andean area of South America. The fluorescent antibody kit from Meridian Diagnostics (Cincinnati, OH) was used to identify some Cryptosporidium species and Giardia species found in feces from the intestines of mummies 500 to 3,000 years old. The specimens that were positive by direct visualization using fluorescent antibody were then tested with an enzyme-linked immunosorbent assay reaction using a Meridian kit just released on the market. Since all of the feces used were formed, it would seem that the organisms found were from carriers rather than active cases of disease. Similar fecal specimens were shown to harbor antigens from Helicobacter pylori almost 3,000 years old.

Effects of housing and colostrum feeding on the prevalence of selected infectious organisms in feces of Jersey calves.

Neonatal Jersey calves (n = 96) were used to evaluate effects of housing (individual hutches or wooden pens in a barn) and colostrum feeding (calves were separated from the dam and fed 2 L of colostrum in nipple-bottles or allowed to nurse the dam for 3 d) on the prevalence of selected organisms in feces. Prevalence of Cryptosporidium and Eimeria were reduced, and prevalence of rotavirus tended to be reduced, when calves were housed in hutches. Prevalence of coronavirus was unaffected by treatment. Weekly prevalence of Giardia was increased when calves were left to nurse the dam for 3 d. Mean prevalence of Cryptosporidia (wk 1 to 4), Eimeria (wk 4 to 5), Giardia, rotavirus, and coronavirus (wk 1 to 5) were 34.7, 20.6, 27.1, 15.8, and 4.9%, respectively. Escherichia coli (K99 positive) were observed in 3 of 174 samples cultured. Methods of housing and colostrum feeding affected acquisition of enteropathogens in this study.

Laboratorio epidemiológico de parasitologia en un centro integrado de salud: Cantón de Los Chiles 1985-1986 / Parasitology epidemiological laboratory in an integrated health center: Cantón le Los Chiles, 1985-1986

Se realizó un estudio de 2.363 pacientes del Cantón de Los Chiles, Prov. de alajuela en los años de 1985 y 1986; a los cuales se les determinó por examen coproparasitoscópico una incidencia de parasitois del 67.75% siendo el parásito más común en todos los grupos de edades investigados, el protozoario Lambia intestinalis y de los helmintos, Trichocephalus trichiurus. Según estudios esfectuados, la causa de esta alta parasitosis se debe entre otros factores, a la escasa calidad sanitaria de los abastecimientos de agua, la poca letrinización y la mala eliminación de las basuras. El nivel socioeconómico bastante bajo de la mayoría de los habitantes, así como la propia idiosincracia y características culturales, han contribuido en alguna forma a agravar este problema. Al comparar los valores encontrados con algunos otros descritos en la literatura, se observó concordancia y similitud en los resultados, de acuerdo a las circunstancias análogas que rodearon el estudio

Risk factors for fatal childhood diarrhea: a case-control study from two remote Panamanian islands.

Between September 1979 and March 1980, distinguishing features between fatal and nonfatal cases of diarrhea caused by the same etiologic agents were sought in a case-control investigation of Cuna Indian children living on the San Blas Islands located off Panama's Caribbean coast. The eight fatal cases of diarrhea (four associated with rotavirus, one with Giardia lamblia, and three without identifiable pathogens), which occurred in a cohort of 186 children aged less than five years who were followed for seven months, were matched with 24 contemporaneously occurring nonfatal cases of diarrhea. Weight-for-length measurements falling below the 90th percentile of the reference standard, reliance on traditional rather than equally as available Western medicine, and failure to receive oral rehydration solution were significantly more common among fatal than nonfatal cases. Incorporating traditional medicine men with their long-standing village-wide authority into expanded community health education programs that emphasize the importance of early treatment of diarrhea with oral rehydration solution would probably reduce mortality associated with diarrheal illness in this population.

Giardiasis: a common, sexually transmissible parasitic diarrhea with pitfalls in diagnosis.

Giardia lamblia is the number one intestinal parasite in the United States. Symptoms of giardiasis include upper abdominal pain and distress, flatulence, nervousness, and diarrhea. Multiple stool specimens examined for ova and parasites by nonexpert parasitologists will frequently not provide the diagnosis, and special studies must then be done. Antibiotics, antidiarrheals, certain enema preparations, and oily laxatives can cause a temporary disappearance of parasites from the stool. Treatment of choice is a five-day course of quinacrine hydrochloride. Recently, attention has been brought to the fact that oral sex may be responsible for transmission in a significant number of cases of giardiasis.

Symposium on diarrhea. 3. Investigation of chronic diarrhea.

The practical approach to the investigation of diarrhea must be logical and based on anatomic considerations. The site of the underlying disorder may be determined by the clinical picture, and the logic of investigation will be influenced by the history. Important specific investigation in a case of colonic diarrhea include a careful rectal examination, stool inspection, sigmoidoscopy, rectal biopsy and barium enema study. Colonoscopy has been used, but its role has yet to be defined. In a case of small-bowel steatorrhea or diarrhea quantitative chemical estimation of the daily output of stool fat is useful, and to this investigation is added a small-bowel radiograph series and, if the radiographic findings are abnormal, small-bowel biopsy. Other investigations for small-bowel disease may include the breath test with carbon-14-labelled glycocholic acid, the lactose tolerance test, duodenal aspiration for giardiasis, analysis of serum immunoglobulins and, on occasion, isolation of vasoactive intestinal polypeptide hormone (which may aid the diagnosis of functioning tumours of the pancreas or small bowel). Investigations for pancreatic steatorrhea include abdominal radiography, performance of the secretin test and testing of the response to pancreatic replacement therapy. In some patients it may be useful to use endoscopic retrograde cholangiopancreatography to differentiate pancreatic carcinoma and chronic pancreatitis.