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Research Project: Development of a Vaccine and Improved Diagnostics for Malignant Catarrhal Fever

Location: Animal Disease Research

Title: Re-emerging/notifiable diseases to watch

item WAINWRIGHT, SHERRILYN - Animal And Plant Health Inspection Service (APHIS)
item Cunha, Cristina
item WEBB, BRETT - North Dakota State University
item McGregor, Bethany
item Drolet, Barbara
item Welch, John

Submitted to: Veterinary Clinics of North America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/25/2024
Publication Date: 3/6/2024
Citation: Wainwright, S.H., Cunha, C.W., Webb, B., Mcgregor, B.L., Drolet, B.S., Welch, J.B. 2024. Re-emerging/notifiable diseases to watch. Veterinary Clinics of North America.

Interpretive Summary: Re-emerging and notifiable diseases of cattle and bison continue to pose potential risks to their production and the livelihoods of producers. Some pathogens are a risk to other animal populations, as well as public health. Recognizing clinical signs suggestive of these diseases is paramount for early detection and response to contain the spread as efficiently as possible, minimizing the potential animal and human health, and economic impacts of these diseases. Immediate reporting to State and Federal Animal Health Officials allows for a quick assessment by a trained Foreign Animal Disease Diagnostician and for official confirmation and an immediate response to prevent further spread. Veterinarians for cattle and bison are our first line of defense to protect the health of the herds and the nation's livestock populations. Knowledge of the animal/herd and local situation is invaluable for identifying prevention and mitigation measures to stop transmission. Bluetongue virus (BTV), Malignant Catarrhal Fever (MCF), and New World Screwworm (NWS) pose imminent risks for exposure and infection of cattle and bison. This chapter provides key aspects of these three re-emerging and notifiable diseases. Understanding their risks and the importance of early detection and reporting can minimize serious negative impacts to animal and human health and livelihoods.

Technical Abstract: Re-emerging and notifiable diseases of cattle and bison continue to pose potential risks to their health and lives, affecting production and the livelihoods of producers. It is essential to understand the clinical presentation of these diseases to watch for possible incursions and infections and to immediately report your suspicions to your State and Federal Animal Health Officials. Three of these re-emerging and notifiable diseases of cattle and bison are presented in this chapter including Bluetongue virus, Malignant Catarrhal Fever, and New World Screwworm. 1. Bluetongue virus (BTV) is a non-contagious, arthropod-borne virus that primarily affects domestic sheep and wild deer species. Cattle usually do not show disease in response to BTV infection, although in some cases disease has been shown with certain strains of the BTV. During an outbreak in Europe of a particularly virulent BTV serotype (BTV-8), not present in North America, captive European bison (Bison bonasus), North American bison (Bison bison), and yaks (Bos grunniens grunniens) showed clinical signs similar to sheep with edema, conjunctivitis, and sudden death reported in all three species. BTV distribution parallels the spatial and temporal distribution of Culicoides spp. (biting midges), which are the biological vectors of the virus. BTV is considered a reportable disease in the U.S. by the USDA Animal and Plant Health Inspection Service (APHIS). Only BTV-8 is considered a notifiable disease in the U.S., while the remaining serotypes are considered monitored diseases by APHIS. BTV is also listed as a reportable disease by the World Organization for Animal Health (WOAH). 2. Different Malignant Catarrhal Fever (MCF) viruses have each co-evolved with a particular animal species. This resulted in adaptation of that species to the virus and consequently, upon infection, these animals usually do not develop disease but remain as asymptomatic carriers, serving as virus reservoirs. Infectious viral particles are shed sporadically from carrier hosts and can infect non-adapted animals which are susceptible to developing MCF. In this scenario, it is important to keep in mind that MCF can emerge anywhere carrier and clinically susceptible hosts are kept at proximity. The vast majority of MCF cases in North America are caused by ovine herpesvirus-2 (OvHV-2) which exists as a ubiquitous subclinical infection in sheep and causes sheep-associated MCF (SA-MCF) in several ungulates, including bison, cattle, deer, and pigs. Although both cattle and bison are susceptible to SA-MCF, cattle are relatively more resistant than bison requiring approximately 1000 times more virus to induce disease. Control and prevention of MCF centers on physical separation of MCF virus carriers from susceptible host species as there are no commercially available vaccines or effective therapies. MCF is listed as a Monitored disease by the National List of Reportable Animal Diseases (NLRAD) System, requiring that licensed veterinarians and veterinary laboratories report occurrence of disease to state and federal animal health officials. 3. New World screwworm (NWS) is a devastating obligate parasite of warm-blooded animals which can negatively impact livestock production, health of companion animals, wildlife populations, and humans, each which can serve as potential hosts, any wound or bodily orifice can serve as a site for females to lay their egg masses which could lead to myiasis. Untreated wounds can lead to hemorrhage, secondary infection, and the death of the host. Using the Sterile Insect Technique (SIT) developed by USDA scientists, the New World Screwworm (NWS) has been eradicated from the U.S., Mexico, Central America, and several Caribbean islands, where it was endemic. The concern is the re-introduction into the U.S. or other NWS-free country. The most common way of introduction of NW