Agriculture emergencies: a primer for first responders

Outbreak of cryptosporidiosis among responders to a rollover of a truck carrying calves - Kansas, April 2013

In April 2013, the Thomas County Health Department notified the Kansas Department of Health and Environment's Infectious Disease Epidemiology and Response section (KDHE) of two cases of cryptosporidiosis among emergency responders to a tractor-trailer rollover. The truck was carrying approximately 350 preweaned Holstein calves. An outbreak investigation was led by KDHE with assistance from the county health department; six cases of cryptosporidiosis were identified among the 15 emergency responders. No additional primary cases with this exposure or secondary cases were identified. Disease was associated with carrying calves (relative risk [RR] = 3.0) and contact with fecal matter (RR = 4.5). The calves were aged <10 days and reportedly suffered from scours (diarrheal disease), which is often caused by Cryptosporidium spp., a chlorine-tolerant protozoan parasite. Because of the age of the calves and the conditions at the rollover scene, a high potential existed for fecal contamination and subsequent transmission of Cryptosporidium. This outbreak is the first report of both law enforcement and volunteer emergency responders contracting cryptosporidiosis, with transmission of Cryptosporidium attributed solely to direct contact with animals and their feces. Human illness resulting from contact with animals during an emergency response might be minimized if 1) all responders are aware of the potential for zoonotic transmission, 2) education is provided on proper animal handling including the use of appropriate personal protective equipment, and 3) responders practice thorough hand hygiene and decontaminate clothing and equipment following contact with feces.

The Microbial Rosetta Stone Central Agricultural Database: An Information Resource on High-Consequence Plant Pathogens

Microbial pathogens of humans, animals, and plants can serve as potential agents of biowarfare, bioterrorism, and biocrime. Previously, the Microbial Rosetta Stone (MRS) Central database, an easily accessible informational resource tool, was developed to assist law enforcement personnel in the event of a disease investigation by providing key information on pathogens of concern. Although the database already contained information on a few high-profile plant pathogens, the coverage was insufficient considering the large number of plant pathogens that pose a threat, not only to agricultural production but also to natural plant resources such as forests and rangelands. In this project, 100 plant pathogens of high consequence were selected for study, existing literature on these agents was reviewed, and both the sources and key pathogen information provided therein were curated in the new Agricultural Database (AgDB), an accessory to the existing MRS Central Database. Chosen for inclusion in the MRS Central AgDB were plant pathogens having significant potential for damage to U.S. agricultural and natural ecosystems. The selection process included review of several previously developed plant-pathogen threat lists and recommendations from experts within the U.S. plant biosecurity community. Pathogen information was collected by searching a number of relevant literature databases, sites on the World Wide Web, and other resources. For inclusion in the MRS, the information was curated into categories: pathogen taxonomy, nomenclature synonyms, disease symptoms and geographic distribution, plant hosts, insect vectors, detection and diagnostic methods, laboratory and field protocols, sample collection, and epidemiology. The resulting AgDB enhances the MRS Central Database by summarizing and linking key information on high-threat plant diseases and their causal agents to relevant scientific literature and internet resources. The AgDB contains critical, key information on high-consequence plant pathogens, curated in a format that is readily accessible and easily searched. The resource enhances the existing MRS Central Database and provides law enforcement, forensic, and investigative personnel with an additional tool with which to respond to microbial emergencies, particularly those affecting the agricultural and environmental sectors.

Mass depopulation of laying hens in whole barns with liquid carbon dioxide: evaluation of welfare impact

Appropriate emergency disaster preparedness is a key priority for agricultural agencies to allow effective response to serious avian disease outbreaks. There is a need to develop rapid, humane, and safe depopulation techniques for poultry that are widely applicable across a range of farm settings. Whole barn depopulation with carbon dioxide (CO(2)) has been investigated as a humane and efficient means of killing large numbers of birds in the event of a reportable disease outbreak. It has also been considered as a method for depopulating barns containing end-of-lay hens, particularly when there is limited local slaughter and rendering capacity. Determining the best method of humanely killing large flocks of birds remains problematic and is being investigated by a coordinated international effort. While whole barn depopulation using CO(2) inhalation has been explored, physiologic responses of chickens have not been characterized in field settings and assessment of animal welfare is hampered without this information. In this study, 12 cull laying hens were surgically instrumented with telemetry transmitters to record electroencephalographs, electrocardiographs, body temperature, and activity during 2 large-scale field CO(2) euthanasia trials of end-of-lay hens. The day following surgery, instrumented hens were placed in barns with other birds, barns were sealed, and animals were killed by CO(2) inhalation delivered via a specially designed liquid CO(2) manifold. Instrumented birds were monitored by infrared thermography, and ambient temperature, CO(2), and O(2) concentrations were recorded. Results from these studies indicate that instrumented hens lost consciousness within 2 min of CO(2) levels reaching 18 to 20%. Mild to moderate head shaking, gasping, and 1 to 2 clonic muscle contractions were noted in hens before unconsciousness; however, brain death followed rapidly (<5 min). Evaluation of welfare costs and benefits suggest clear advantages over catching and transporting cull hens for slaughter. The financial costs with this method are greater, however, than those estimated for traditional slaughter techniques. Results of these studies are being used to develop national protocols for whole barn depopulation of hens by CO(2) inhalation.