Educating pastoralists and extension officers on diverse livestock diseases in a changing environment in Tanzania

East African pastoralists and their livestock are vulnerable to alterations in resource availability and disease transmission and frequently face poor access to livestock health services. Government veterinarians tasked with guiding health services must prioritize livestock health risks and allocate limited resources across disparate ecosystems with different disease threats. To identify livestock diseases of concern and strategies for improving herd health and resilience, we conducted community focus groups with pastoralists and interviewed pastoralist household leaders, village extension officers, and government veterinary officials in south-central Tanzania, an area experiencing rapid population growth and environmental change. All participants discussed pastoralist access to livestock health services, livestock disease priorities, and means to improve livestock health. Perceptions of diseases of importance differed among pastoralists, extension officers, and government veterinarians. Spatial differences in diseases of concern among study area pastoralists emphasized the need for locally adaptable livestock health service delivery. Although pastoralist strategies to improve livestock health differed by ethnic group, many pastoralists as well as extension officers and government veterinarians identified livestock health education and training for pastoralists and extension officers as a critical need. Policies designed at the regional, rather than the local, level may not reflect the disease concerns of the entire area. To effectively address veterinary health problems and make livestock herds more resilient to environmental change, conditions at the local level must be considered. Education targeted to pastoralist households and extension officers could achieve greater flexibility in the livestock health system and provide more reliable information about local conditions for governmental policymakers

Sentinel California sea lions provide insight into legacy organochlorine exposure trends and their association with cancer and infectious disease

Background: Organochlorine contaminants (OCs), like polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethanes (DDTs), are widespread marine pollutants resulting from massive historical use and environmental persistence. Exposure to and health effects of these OCs in the marine environment may be examined by studying California sea lions (Zalophus californianus), which are long lived, apex predators capable of accumulating OCs. Methods: We evaluated PCB and DDT levels in 310 sea lions sampled between 1992 and 2007: 204 individuals stranded along the coast of central California, 60 healthy males from Washington State, and 46 healthy females from southern California. Lipid-normalized contaminant concentrations were analyzed using general linear models and logistic regression to ascertain temporal trends; differences between stranded and healthy sea lions; and association of organochlorines with sex, age, and presence of cancer or fatal infectious disease. Results: Concentrations of the contaminants in stranded adults decreased over time in the study period (adjusted for sex, as adult males had higher mean blubber concentrations than adult females and juveniles). Cancer was almost eight and six times more likely in animals with higher summed PCBs and DDTs, compared to those with lower levels (95% CI 5.55-10.51 and 4.54-7.99, respectively). Fatal infectious diseases were similarly seven and five times more likely in animals with higher contaminant burdens (95% CI 4.20-10.89 and 3.27-7.86, respectively). Mean contaminant loads were significantly higher in stranded sea lions than in healthy live captured animals (p b 0.001). Conclusion: Organochlorine contamination has significant associations with health outcomes in California sea lions, raising concerns for humans and other animals eating tainted seafood. While environmental exposure to these organochlorines appears to be decreasing over time based on levels in sea lion tissues, their persistence in the environment and food web for all predators, including humans, and the associated serious health risks, warrant monitoring, possibly through sentinel species like marine mammals

Toxoplasma gondii, source to sea: higher contribution of domestic felids to terrestrial parasite loading despite lower infection prevalence

Abstract: Environmental transmission of Toxoplasma gondii, a global zoonotic parasite, adversely impacts human and animal health. Toxoplasma is a significant cause of mortality in threatened Southern sea otters, which serve as sentinels for disease threats to people and animals in coastal environments. As wild and domestic felids are the only recognized hosts capable of shedding Toxoplasma oocysts into the environment, otter infection suggests land-to-sea pathogen transmission. To assess relative contributions to terrestrial parasite loading, we evaluated infection and shedding among managed and unmanaged feral domestic cats, mountain lions, and bobcats in coastal California, USA. Infection prevalence differed among sympatric felids, with a significantly lower prevalence for managed feral cats (17%) than mountain lions, bobcats, or unmanaged feral cats subsisting on wild prey (73-81%). A geographic hotspot of infection in felids was identified near Monterey Bay, bordering a high-risk site for otter infection. Increased odds of oocyst shedding were detected in bobcats and unmanaged feral cats. Due to their large populations, pet and feral domestic cats likely contribute more oocysts to lands bordering the sea otter range than native wild felids. Continued coastal development may influence felid numbers and distribution, increase terrestrial pathogens in freshwater runoff, and alter disease dynamics at the human-animal-environment interface

Coastal development and precipitation drive pathogen flow from land to sea: evidence from a Toxoplasma gondii and felid host system

Rapidly developing coastal regions face consequences of land use and climate change including flooding and increased sediment, nutrient, and chemical runoff, but these forces may also enhance pathogen runoff, which threatens human, animal, and ecosystem health. Using the zoonotic parasite Toxoplasma gondii in California, USA as a model for coastal pathogen pollution, we examine the spatial distribution of parasite runoff and the impacts of precipitation and development on projected pathogen delivery to the ocean. Oocysts, the extremely hardy free-living environmental stage of T. gondii shed in faeces of domestic and wild felids, are carried to the ocean by freshwater runoff. Linking spatial pathogen loading and transport models, we show that watersheds with the highest levels of oocyst runoff align closely with regions of increased sentinel marine mammal T. gondii infection. These watersheds are characterized by higher levels of coastal development and larger domestic cat populations. Increases in coastal development and precipitation independently raised oocyst delivery to the ocean (average increases of 44% and 79%, respectively), but dramatically increased parasite runoff when combined (175% average increase). Anthropogenic changes in landscapes and climate can accelerate runoff of diverse pathogens from terrestrial to aquatic environments, influencing transmission to people, domestic animals, and wildlife

Ranking the risk of animal-to-human spillover for newly discovered viruses

The death toll and economic loss resulting from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic are stark reminders that we are vulnerable to zoonotic viral threats. Strategies are needed to identify and characterize animal viruses that pose the greatest risk of spillover and spread in humans and inform public health interventions. Using expert opinion and scientific evidence, we identified host, viral, and environmental risk factors contributing to zoonotic virus spillover and spread in humans. We then developed a risk ranking framework and interactive web tool, SpillOver, that estimates a risk score for wildlife-origin viruses, creating a comparative risk assessment of viruses with uncharacterized zoonotic spillover potential alongside those already known to be zoonotic. Using data from testing 509,721 samples from 74,635 animals as part of a virus discovery project and public records of virus detections around the world, we ranked the spillover potential of 887 wildlife viruses. Validating the risk assessment, the top 12 were known zoonotic viruses, including SARS-CoV-2. Several newly detected wildlife viruses ranked higher than known zoonotic viruses. Using a scientifically informed process, we capitalized on the recent wealth of virus discovery data to systematically identify and prioritize targets for investigation. The publicly accessible SpillOver platform can be used by policy makers and health scientists to inform research and public health interventions for prevention and rapid control of disease outbreaks. SpillOver is a living, interactive database that can be refined over time to continue to improve the quality and public availability of information on viral threats to human health

Isolation of Angola-like Marburg virus from Egyptian rousette bats from West Africa.

Marburg virus (MARV) causes sporadic outbreaks of severe Marburg virus disease (MVD). Most MVD outbreaks originated in East Africa and field studies in East Africa, South Africa, Zambia, and Gabon identified the Egyptian rousette bat (ERB; Rousettus aegyptiacus) as a natural reservoir. However, the largest recorded MVD outbreak with the highest case-fatality ratio happened in 2005 in Angola, where direct spillover from bats was not  shown. Here, collaborative studies by the Centers for Disease Control and Prevention, Njala University, University of California, Davis USAID-PREDICT, and the University of Makeni identify MARV circulating in ERBs in Sierra Leone. PCR, antibody and virus isolation data from 1755 bats of 42 species shows active MARV infection in approximately 2.5% of ERBs. Phylogenetic analysis identifies MARVs that are similar to the Angola strain. These results provide evidence of MARV circulation in West Africa and demonstrate the value of pathogen surveillance to identify previously undetected threats

Dead or alive: animal sampling during Ebola hemorrhagic fever outbreaks in humans

There are currently no widely accepted animal surveillance guidelines for human Ebola hemorrhagic fever (EHF) outbreak investigations to identify potential sources of Ebolavirus (EBOV) spillover into humans and other animals. Animal field surveillance during and following an outbreak has several purposes, from helping identify the specific animal source of a human case to guiding control activities by describing the spatial and temporal distribution of wild circulating EBOV, informing public health efforts, and contributing to broader EHF research questions. Since 1976, researchers have sampled over 10,000 individual vertebrates from areas associated with human EHF outbreaks and tested for EBOV or antibodies. Using field surveillance data associated with EHF outbreaks, this review provides guidance on animal sampling for resource-limited outbreak situations, target species, and in some cases which diagnostics should be prioritized to rapidly assess the presence of EBOV in animal reservoirs. In brief, EBOV detection was 32.7% (18/55) for carcasses (animals found dead) and 0.2% (13/5309) for live captured animals. Our review indicates that for the purposes of identifying potential sources of transmission from animals to humans and isolating suspected virus in an animal in outbreak situations, (1) surveillance of free-ranging non-human primate mortality and morbidity should be a priority, (2) any wildlife morbidity or mortality events should be investigated and may hold the most promise for locating virus or viral genome sequences, (3) surveillance of some bat species is worthwhile to isolate and detect evidence of exposure, and (4) morbidity, mortality, and serology studies of domestic animals should prioritize dogs and pigs and include testing for virus and previous exposure

The Earth BioGenome Project 2020: Starting the clock

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