Disease Surveillance Systems in Animal Health
Over the past year, the Food Safety Network has partnered with Animal and Plant Health Inspection Service (APHIS) Veterinary Services to develop an online learning module covering topics related to animal health and emergency preparedness and response. To commemorate this work, the Food Safety Network is releasing a series of blogs focused on select topics discussed within this online learning module. This blog is the first in a six-part series and focuses on the topic of disease surveillance systems in animal health.
World population growth creates a significant challenge for food production and food security, especially in developing regions. Livestock production systems are becoming more intensified to meet the challenges of feeding nearly 8 billion people. Greater animal density within livestock production systems, along with increased movement of animals and animal products, both domestically and globally, increases the risk of disease incursions and rapid disease dissemination within a herd or flock. With human and livestock populations on the rise, greater pressure has been placed on wildlife habitats, resulting in closer contact. Thus, the impact of poor animal health practices not only affects producers, agricultural industries and national livestock health, but can result in disruptions to domestic markets and international trade.
Animal health practices vary among different regions of the world. These practices are influenced by a number of factors, including, but not limited to, the region’s livestock demographics, regional animal health status, as well as economic, cultural and social circumstances. Because of these differences, there is not a one-size-fits-all blueprint for animal health practices. Yet, there are international guidelines and resources for improvement of animal health across the globe.
The risks of insufficient animal health practices within a region, particularly inadequate disease surveillance systems, are the inability to rapidly detect disease, implement emergency response measures and prevent the spread of disease. Many diseases can be transmitted from one animal to another during the incubation period, which is the period of time before the infected animal exhibits clinical signs. Other diseases may go unrecognized or mistaken for other less severe health conditions due to common clinical symptoms. Prior to disease detection, the infectious agent can be transmitted, directly or indirectly, within the herd and/or farm-to-farm.
If a disease cannot be detected and contained in a timely manner, the disease can spread throughout the region or the entire country, resulting in increased morbidity and mortality, animal and production losses, disease and indemnity costs, and, perhaps mostly importantly, international trade losses. Even diseases localized to a smaller part of a country can result in trading partners banning imports of animal commodities from part or all of the country. In some cases, it can take several years after the disease outbreak for a country to lift trade restrictions and restore international trade markets.
Spotlight Story: Highly Pathogenic Avian Influenza: United States
Highly pathogenic avian influenza (HPAI) is a severe, highly contagious type of influenza virus noted for its high death rate in poultry. Certain strains of HPAI can also be transmitted to humans, causing severe illness or death. Wild birds can serve as a carrier of the virus and show few to no symptoms. HPAI has been detected in animals but they are not a significant source of the virus.
In January 2015, a strain of HPAI virus was detected in a commercial turkey flock within the United States. Analysis of the virus indicated the flock strain was similar to ones associated with migratory bird samples from that region of the country. The infected flock was quickly destroyed and the virus contained. Soon after, however, a different strain of the HPAI virus was detected in a second commercial turkey flock. The flock was in a poultry-dense region of the country and the virus spread rapidly throughout commercial turkey and chicken flocks within several states. By the end of the six-month outbreak, more than 50 million turkeys and chickens had died or were destroyed in an effort to stop the spread of the HPAI virus. The cost to the U.S. domestic poultry industry, as a result of the outbreak, was an estimated $3.3 billion in lost production and export opportunities. In addition to industry losses, the U.S. government spent $879 million to mitigate and control the disease.
What is Surveillance?
Surveillance is the continuous, organized collection and analysis of information related to animal health and its timely distribution to applicable authorities who will leverage this data to take action. For every transboundary animal disease, there is a predetermined set of activities, or components, which produce data that can inform the status of the disease in a population. Whether a country relies on one or more of these components to collect surveillance data, all of these strategies make up that country’s surveillance system. There are many different characteristics of a disease surveillance system. These traits include, but are not limited to, the following:
- Origin of surveillance information — How is the surveillance information being collected?
- Disease focus — Is the surveillance focused on a specific disease or pathogen?
- Representativeness — How well does the information being gathered represent the population of interest?
- Type of data collected — What information is begin collected during the surveillance process.
- Cost and practicality — How cost effective is the surveillance system being used?
According to the Food and Agriculture Organization of the United Nations (FAO),“In order to design an effective surveillance system, two things are required: (1) an understanding of available surveillance options and (2) an ability to compare and evaluate the different options, so that you can decide on the best combination.”
When considering which surveillance approach to implement, it is important to know the different ways in which surveillance can be carried out. Some of the most popular surveillance options are briefly described below:
- Passive disease reporting systems — A type of general surveillance where the producer or animal health professional identifies sick animals on the premises and contacts their local veterinary authority or veterinarian for help.
- Abbatoir or slaughterhouse — Highly variable across countries or individual areas, this type of passive surveillance takes place postmortem during the observation of carcasses or meat products.
- Surveys — A form of active surveillance where the design and data collected can be representative or risk based.
- Syndromic and indirect surveillance — The identification of specific patterns and signs, or groups thereof, and their analysis of this information in a specific environment and time.
- Negative reporting (zero reporting) — A type of passive surveillance focused on providing evidence of freedom from disease.
- Participatory disease surveillance — A type of surveillance where farmers are interviewed to better understand their problems and needs.
According to FAO, “Managing disease threats poses enormous challenges and requires inputs from many disciplines. Good quality information is an essential requirement: what diseases exist; where they are found; what impact they are having; which populations are at risk; how we can prevent, control or eradicate these diseases. Animal disease surveillance plays a central role in providing this information.” The lack of a disease surveillance program delays identification of outbreaks and increases the likelihood of farm-to-farm disease spread.
Just as important as good animal health practices on the farm, it is essential for countries to have a disease surveillance system in place that can enable veterinary authorities to detect disease early and respond quickly. The 2014-2015 outbreak of HPAI in the United States taught our nation many valuable lessons related to disease surveillance and the importance of being proactive when it comes to emerging threats. Since the conclusion of the outbreak, the United States has worked to establish one of the most comprehensive avian influenza surveillance plans in the world that incorporates private and public surveillance efforts from wildlife agencies, voluntary programs and industry associations, along with regulatory testing, to remain vigilant in detecting and eradicating disease as quickly as possible. It is critical to support all efforts to decrease the risk of transboundary threats to public and animal health. Disease surveillance systems serve as an early-warning system to provide data that drives decisions amongst key players when stakes are high and action must be taken quickly.
Want to learn more about the concept of animal health? Check out our free, self-paced, online Animal Health Learning Module which explores the evolution of the U.S. surveillance process, the value of a modern surveillance system and emergency response process, international trade and animal health, import risk analysis, risk management and risk communication, emergency preparedness and response, and concludes with a case study that allows learners to walk through a fictional country’s response to an African Swine Fever outbreak. Visit http://www.spscourses.com today to sign up for a free account and access this module and so much more!