Antibiotic-resistant Salmonella in swine wastes and farm surface waters.

Hog production takes place mostly in large concentrated animal feeding operations (CAFOs) where waste is managed by storing in lagoons prior to land application of lagoon liquid. Salmonella, including antibiotic-resistant Salmonella, have been found in the farm environment and lagoons. The objective of this research was to determine whether Salmonella resistant to clinically relevant antibiotics were present in wastewaters and surface waters from hog CAFOs. Samples of hog waste and on farm environmental waters were analysed for Salmonella, which were tested for antimicrobial susceptibility. The highest percentage of resistant isolates were found in raw waste flushed from hog houses and in lagoon wastewater; few resistant isolates were found in on-farm surface water. Resistance to sulphamethoxazole was most common, mostly in waste samples and less commonly in surface water, followed by chloramphenicol and ampicillin. No resistance to cephalosporin or fluoroquinolones was found. Resistance to clinically relevant antibiotics was commonly found in Salmonella from hog waste but was less extensive in farm surface waters. Management of wastes from hog CAFOs should be designed to further reduce the risk of human exposures resulting from environmental contamination with Salmonella. SIGNIFICANCE AND IMPACT OF THE STUDY: This study suggests antibiotic-resistant Salmonella were common in hog wastes and present in environmental waters associated with hog CAFOs. Low levels of antibiotic-resistant Salmonella in on-farm stream waters suggest surface waters could have been contaminated, potentially serving as a mechanism of off-farm transport. Since the study, there have been multiple economic, regulatory and practice changes at the federal, state and industry level. These include regulation of antibiotic use and animal waste treatment, vertical integration in the industry and changes in antibiotic use practice. This study is a useful historical baseline against which current antibiotic resistance trends can be measured.

Environmental Survey of Drinking Water Sources in Kampala, Uganda, during a Typhoid Fever Outbreak.

In 2015, a typhoid fever outbreak began in downtown Kampala, Uganda, and spread into adjacent districts. In response, an environmental survey of drinking water source types was conducted in areas of the city with high case numbers. A total of 122 samples was collected from 12 source types and tested for Escherichia coli, free chlorine, and conductivity. An additional 37 grab samples from seven source types and 16 paired large volume (20 liter) samples from wells and springs were also collected and tested for the presence of Salmonella enterica serovar Typhi. Escherichia coli was detected in 60% of kaveras (drinking water sold in plastic bags) and 80% of refilled water bottles; free chlorine was not detected in either source type. Most jerry cans (68%) contained E. coli and had free chlorine residuals below the WHO-recommended level of 0.5 mg/liter during outbreaks. Elevated conductivity readings for kaveras, refilled water bottles, and jerry cans (compared to treated surface water supplied by the water utility) suggested that they likely contained untreated groundwater. All unprotected springs and wells and more than 60% of protected springs contained E. coli Water samples collected from the water utility were found to have acceptable free chlorine levels and no detectable E. coli While S Typhi was not detected in water samples, Salmonella spp. were detected in samples from two unprotected springs, one protected spring, and one refilled water bottle. These data provided clear evidence that unregulated vended water and groundwater represented a risk for typhoid transmission.IMPORTANCE Despite the high incidence of typhoid fever globally, relatively few outbreak investigations incorporate drinking water testing. During waterborne disease outbreaks, measurement of physical-chemical parameters, such as free chlorine residual and electrical conductivity, and of microbiological parameters, such as the presence of E. coli or the implicated etiologic agent, in drinking water samples can identify contaminated sources. This investigation indicated that unregulated vended water and groundwater sources were contaminated and were therefore a risk to consumers during the 2015 typhoid fever outbreak in Kampala. Identification of contaminated drinking water sources and sources that do not contain adequate disinfectant levels can lead to rapid targeted interventions.

Binational outbreak of Guillain-Barré syndrome associated with Campylobacter jejuni infection, Mexico and USA, 2011.

In June 2011, a cluster of suspected cases of Guillain-Barré syndrome (GBS), which can follow Campylobacter jejuni infection, was identified in San Luis Río Colorado (SLRC), Sonora, Mexico and Yuma County, Arizona, USA. An outbreak investigation identified 26 patients (18 from Sonora, eight from Arizona) with onset of GBS 4 May-21 July 2011, exceeding the expected number of cases (n = 1-2). Twenty-one (81%) patients reported antecedent diarrhoea, and 61% of 18 patients tested were seropositive for C. jejuni IgM antibodies. In a case-control study matched on age group, sex, ethnicity, and neighbourhood of residence, all Arizona GBS patients travelled to SLRC during the exposure period vs. 45% of matched controls (matched odds ratio 8·1, 95% confidence interval 1·5-∞). Exposure information and an environmental assessment suggested that GBS cases resulted from a large outbreak of C. jejuni infection from inadequately disinfected tap water in SLRC. Binational collaboration was essential in investigating this cross-border GBS outbreak, the first in mainland North America since 1976.

Giardiasis outbreak at a camp after installation of a slow-sand filtration water-treatment system.

In July and August 2007, a giardiasis outbreak affected attendees of a private recreational camp in California. Twenty-six persons had laboratory-confirmed giardiasis; another 24 had giardiasis-like illness with no stool test. A retrospective cohort study determined that showering was associated with illness (adjusted odds ratio 3·1, 95% confidence interval 1·1-9·3). Two days before the outbreak began, the camp had installed a slow-sand water filtration system that included unsterilized sand. Review of historical water-quality data identified substantially elevated total coliform and turbidity levels in sand-filtered spring water used for showering during the suspected exposure period. Unfiltered spring water tested at the same time had acceptable coliform and turbidity levels, implicating the filtration system as the most likely contamination source. To prevent waterborne illness, slow-sand water filtration systems should use sterilized sand, and slow-sand-filtered water should not be used for any purpose where inadvertent ingestion could occur until testing confirms its potability.

Outbreak of giardiasis associated with a community drinking-water source.

Giardiasis is a common waterborne gastrointestinal illness. In 2007, a community giardiasis outbreak occurred in New Hampshire, USA. We conducted a cohort study to identify risk factors for giardiasis, and stool and environmental samples were analysed. Consuming tap water was significantly associated with illness (risk ratio 4.7, 95% confidence interval 1.5-14.4). Drinking-water samples were coliform-contaminated and a suspect Giardia cyst was identified in a home water filter. One well was coliform-contaminated, and testing indicated that it was potentially under the influence of surface water. The well was located 12.5 m from a Giardia-contaminated brook, although the genotype differed from clinical specimens. Local water regulations require well placement at least 15 m from surface water. This outbreak, which caused illness in 31 persons, represents the largest community drinking-water-associated giardiasis outbreak in the USA in 10 years. Adherence to well placement regulations might have prevented this outbreak.

Broadly reactive TaqMan assay for real-time RT-PCR detection of rotavirus in clinical and environmental samples. JIN2@cdc.gov.

Rotaviruses are enteric pathogens responsible for a significant burden of disease, especially in children, through person-to-person transmission and exposure to contaminated food and water. In the present study, a TaqMan probe-based real-time reverse transcriptase (RT) polymerase chain reaction (PCR) assay was developed and validated for sensitive and specific detection and quantification of rotavirus for the routine screening of clinical and environmental samples. The assay primers and probes were designed to target the non-structural protein region 3 (NSP3) of rotavirus. The rotavirus real-time RT-PCR assay was found to be specific to rotavirus, but broadly reactive to rotavirus genogroups 1-4, 9, 10 and 12. Specificity testing did not identify any cross-reactivity of the assay with a panel of 36 non-rotavirus enteric virus specimens. The sensitivity of the assay was determined using quantified rotavirus stocks and a plasmid DNA stock. Estimated detection limits in reagent-grade water were five genome equivalent copies (GEC) per reaction and two to four rotavirus particles per reaction. The sensitivity of the assay for detecting rotaviruses in environmental water samples was found to be six virus particles per reaction. The rotavirus real-time RT-PCR assay was effective in detecting rotavirus in all 79 stool specimens obtained from a hospital in India. The results of this study demonstrate that the real-time RT-PCR assay for rotavirus is broadly reactive, specific, and sensitive for detection of rotaviruses in clinical specimens and water samples.

Efficacy of a solar concentrator to Inactivate E. coli and C. perfringens spores in latrine waste in Kenya.

Alternative sanitation options are needed for effective waste management in low-income countries where centralized, large-scale waste treatment is not easily achievable. A newly designed solar concentrator technology utilizes solar thermal energy to treat feces contained in drums. This pilot study assessed the efficacy of the new design to inactivate microbes in 13 treatment drums under field conditions in Kenya. Three-quarters of the drums contained <1000 E. coli/g of total solids following 6 h of solar thermal treatment and inactivation of thermotolerant C. perfringens spores ranged from <1.8 to >5.0 log10. Nearly all (94%) samples collected from treatment drums achieved thermophilic temperatures (>50 °C) during the treatment period, however this alone did not ensure samples met the WHO E. coli guideline; higher, sustained thermophilic temperatures tended to be more effective in reaching this guideline. The newly designed solar concentrator was capable of inactivating thermotolerant, environmentally-stable microorganisms as, or possibly more, efficiently than a previous design. Additional data are needed to better characterize how temperature, time, and other parameters affect the ability of the solar concentrator to inactivate microbes in feces.

Detection and differentiation of Cryptosporidium hominis and Cryptosporidium parvum by dual TaqMan assays.

Rapid identification of the two major species of Cryptosporidium associated with human infections, Cryptosporidium hominis and Cryptosporidium parvum, is important for investigating outbreaks of cryptosporidiosis. This study reports the development and validation of a real-time PCR TaqMan procedure for detection of Cryptosporidium species and identification of C. hominis and C. parvum in stool specimens. This procedure comprised a generic TaqMan assay targeting the 18S rRNA for sensitive detection of Cryptosporidium species, as well as two other TaqMan assays for identification of C. hominis and C. parvum. The generic Cryptosporidium species assay can be duplexed with the C. parvum-specific assay. The generic Cryptosporidium species assay was able to detect ten Cryptosporidium species and did not cross-react with a panel of ten other protozoan parasites. The generic Cryptosporidium species assay could detect 1-10 oocysts in a 300 microl stool specimen, whilst each of the species-specific TaqMan assays had detection sensitivities that were approximately tenfold higher. The 18S rRNA assay was found to detect Cryptosporidium species in 49/55 DNA extracts from stool specimens containing either C. hominis or C. parvum. The C. hominis TaqMan assay correctly identified C. hominis in 24/31 validation panel specimens containing this species. The C. parvum-specific assay correctly identified C. parvum in 21/24 validation panel specimens containing this species. This real-time PCR procedure was used to detect and identify C. hominis and C. parvum in stool specimens from outbreak investigations in the USA and Botswana, resulting in identification of C. hominis and/or C. parvum in 66/67 stool specimens shown to be positive for these species using other techniques. From the outbreak specimens tested, the TaqMan procedure was found to have a specificity of 94%. This TaqMan PCR procedure should be a valuable tool for the laboratory diagnosis of cryptosporidiosis caused by C. hominis and C. parvum during outbreak investigations.

Removal of Salmonella and microbial indicators in constructed wetlands treating swine wastewater.

Reductions of Salmonella bacteria and enteric microbial indicator organisms were measured in swine wastewater treated by a field-scale surface flow (SF) constructed wetland at a commercial hog nursery in North Carolina and in laboratory-scale SF and subsurface flow (SSF) constructed wetland reactors. Overall reductions of Salmonella, fecal coliforms and E. coli were 96, 98 and 99%, respectively, in the two-cell field-scale wetland. Somatic and F-specific coliphage viral indicators were reduced by 99 and 98%, respectively. Reductions of Salmonella, fecal coliforms and E. coli were similar in the first cell of the field system and in the laboratory-scale SF wetland operated at a TKN loading of 25 kg ha(-1) d(-1) and 30 degrees C (approximately 70, 90 and 90%, respectively). In the SSF wetland reactor, Salmonella and fecal coliform reductions were 80 and 98%, respectively, at a 40 kg TKN ha(-1) d(-1) loading and 99.8 and 99.99%, respectively, at a 10 kg TKN ha(-1) d(-1) loading. These results show that SF constructed wetlands can be effective for reducing enteric pathogens in swine wastewater and that greater removals can be achieved using SSF designs and lower TKN loading rates.

Health, safety, and environmental concerns of farm animal waste.

Modern animal husbandry has been concerned with increasing efficiency by increasing the number of animals raised per unit area; decreasing labor costs by automated animal feeding, watering, and housing; and using antibiotics to increase animal growth rates. These changes in animal production practices have resulted in reduced disease risks in some cases, but also have introduced new risks and challenges to the animal handler. Topics covered here include exposure pathways and health hazards associated with animal excreta, birthing wastes, and carcasses, with emphasis on infectious microbes (e.g., bacterial, viral, and protozoan pathogens) and airborne hazards (e.g., gases, dust particles, aerosols, and odors). Measures for reducing risks to animal handlers, including the use of waste management and treatment techniques, are reviewed.