Identification of high-risk contact areas between feral pigs and outdoor-raised pig operations in California: Implications for disease transmission in the wildlife-livestock interface.

The US is currently experiencing a return to raising domestic pigs outdoors, due to consumer demand for sustainably-raised animal products. A challenge in raising pigs outdoors is the possibility of these animals interacting with feral pigs and an associated risk of pathogen transmission. California has one of the largest and widest geographic distributions of feral pigs. Locations at greatest risk for increased contact between both swine populations are those regions that contain feral pig suitable habitat located near outdoor-raised domestic pigs. The main aim of this study entailed identifying potential high-risk areas of disease transmission between these two swine populations. Aims were achieved by predicting suitable feral pig habitat using Maximum Entropy (MaxEnt); mapping the spatial distribution of outdoor-raised pig operations (OPO); and identifying high-risk regions where there is overlap between feral pig suitable habitat and OPO. A MaxEnt prediction map with estimates of the relative probability of suitable feral pig habitat was built, using hunting tags as presence-only points. Predictor layers were included in variable selection steps for model building. Five variables were identified as important in predicting suitable feral pig habitat in the final model, including the annual maximum green vegetation fraction, elevation, the minimum temperature of the coldest month, precipitation of the wettest month and the coefficient of variation for seasonal precipitation. For the risk map, the final MaxEnt model was overlapped with the location of OPOs to categorize areas at greatest risk for contact between feral swine and domestic pigs raised outdoors and subsequent potential disease transmission. Since raising pigs outdoors is a remerging trend, feral pig numbers are increasing nationwide, and both groups are reservoirs for various pathogens, the contact between these two swine populations has important implications for disease transmission in the wildlife-livestock interface.

Risk factors of Shiga toxin-producing Escherichia coli in livestock raised on diversified small-scale farms in California.

The increasing number of diversified small-scale farms (DSSF) that raise outdoor-based livestock in the USA reflects growing consumer demand for sustainably produced food. Diversified farms are small scale and raise a combination of multiple livestock species and numerous produce varieties. This 2015-2016 cross-sectional study aimed to describe the unique characteristics of DSSF in California, estimate the prevalence of Shiga toxin-producing Escherichia coli (STEC) in livestock and evaluate the association between risk factors and the presence of STEC in livestock, using generalised linear mixed models. STEC prevalence was 13.62% (76/558). Significant variables in the mixed-effect logistic regression model included daily maximum temperature (OR 0.95; CI95% 0.91-0.98), livestock sample source (cattle (OR 4.61; CI95% 1.64-12.96) and sheep (OR 5.29; CI95% 1.80-15.51)), multiple species sharing the same barn (OR 6.23; CI95% 1.84-21.15) and livestock having contact with wild areas (OR 3.63; CI95% 1.37-9.62). Identification of STEC serogroups of public health concern (e.g. O157:H7, O26, O103) in this study indicated the need for mitigation strategies to ensure food safety by evaluating risk factors and management practices that contribute to the spread and prevalence of foodborne pathogens in a pre-harvest environment on DSSF.

First Report of Ophidiomycosis in a Free-Ranging California Kingsnake (Lampropeltis californiae) in California, USA.

Ophidiomycosis (snake fungal disease) is an emerging threat to snake health worldwide. We report a case of disseminated ophidiomycosis in a California kingsnake (Lampropeltis californiae) from Plymouth, Amador County, California, US, which is the first report of the disease in this species and in a free-ranging snake in California.

Persistence of Escherichia coli in the soil of an organic mixed crop-livestock farm that integrates sheep grazing within vegetable fields.

Mixed crop-livestock farms (MCLF) integrate livestock and crops using their animals to graze crop residues and/or cover crops. MCLF are considered sustainable because grazing and the manure deposited by livestock enhance soil fertility and recycles farm nutrients. However, livestock manure may introduce enteric foodborne pathogens to the soil, which could contaminate fresh produce. Organic farmers in the United States follow the USDA National Organic Program (NOP) standards, which require 90 or 120 days between incorporating raw manure into the soil and harvest. Although not specifically addressed in NOP, organic farmers using grazing within production fields may also use this standard. The objectives of this study were to generate preharvest data to assess the die-off of generic Escherichia coli (E. coli) in the soil, after cover crops were grazed by sheep; and assess the genetic relatedness of generic E. coli isolates between soil and sheep faecal samples. We conducted a repeated observational study to evaluate the persistence of generic E. coli, as an indicator of faecal contamination and surrogate for STEC, in the soil of two fields (A and B) on an organic MCLF. Results showed a 3.70 log10 reduction in mean generic E. coli concentration MPN in the soil of field A from the highest of 3.70 log10 MPN/g on 48 day postsheep grazing (DPS) to -0.70 log10 MPN/g on 139 DPS. Field B showed a 3.51 log10 reduction in mean generic E. coli concentration in the soil from the highest mean of 3.51 log10 MPN/g on 14 DPS to the lowest mean -0.35 log10 MPN/g on 112 DPS. STEC prevalence in the sheep flock was 4.17% (1/24). Closely related generic E. coli strains were found between soil and faecal samples. Developing research-based waiting periods between grazing and harvest is important to inform best practices for farmers and food safety regulators.

"Locusts are now our beef": adult mortality and household dietary use of local environmental resources in rural South Africa.

UNLABELLED: There is currently a lack of research on the association between demographic dynamics and household use of natural resources in rural Africa. Such work is important because in rural Africa natural resources buffer households against shocks, offering both sustenance and income-generating potential. AIMS: The article focuses on adult mortality as a household shock, examining use of local environmental resources as related to household dietary needs. METHODS: The authors analyze two sources of data collected during May-December 2004 in the MRC/Wits Rural Public Health and Health Transitions Research Unit (Agincourt) in rural South Africa. Quantitative analyses use survey data from 240 households, stratified by adult mortality experience. Qualitative data are based on 31 interviews with members of households having recently experienced adult mortality. RESULTS: The interviews provide insight into a variety of household-level mortality impacts and also suggest the importance of proximate resources in the maintenance of food security following the loss of an adult household member. Quantitatively, there are significant differences, both in patterns of usage of the natural environment and in levels of food security, between households that have lost an adult and those that have not. The association between mortality and household use of local environmental resources is further shaped by the gender of the deceased and the time elapsed since the death. CONCLUSIONS: Adult mortality, particularly the death of a male wage-earner, affects household food security. Time allocation is affected as resource collection responsibilities shift, and wild foods may substitute for previously purchased goods.