Field Epidemiology: Disease Control & Investigation

Definition of Field Epidemiology

• Field epidemiology applies epidemiological methods to unexpected health issues in the field
• It emphasizes rapid response and real-time data collection to manage health crises
• It involves collaboration between veterinarians, public health officials, and researchers

Importance in Disease Control

• Crucial for identifying and controlling disease outbreaks in animal populations
• Enhances public health by preventing zoonotic diseases from spreading to humans
• Supports economic stability by protecting livestock and ensuring food security
• Facilitates timely interventions to minimize the impact of outbreaks on communities

Overview of Outbreak Investigation

• Disease outbreak investigation identifies the sources and causes of disease outbreaks in animal populations
• It ensures timely responses to outbreaks and can prevent the spread of diseases to humans and other animals
• It discovers new diseases, or gaining a better understanding of existing ones, ultimately protecting public health and animal welfare

Types of Disease Outbreaks

• Epidemics are characterized by an increase in cases above what is expected, affecting a population or region
• Examples of epidemics include '20 students from the veterinary medicine course vomiting' and '10 cows dead on a farm'
• Endemic diseases are consistently present within a specific geographic area or population; an example is 1 case of foot-and-mouth disease in a pig
• Zoonotic outbreaks involve diseases that can be transmitted from animals to humans; an example is 1 case of Ebola in Portugal which highlights the potential for global health threats

Reasons for Outbreak Investigation

• Identifying and eliminating the source of an outbreak is crucial to prevent further spread and protect the population
• Investigating outbreaks allows for discovering new diseases or gaining a better understanding of existing ones.
• Monitoring the severity and transmissibility of outbreaks informs public health responses
• Evaluating outbreaks can lead to improvements in surveillance systems, ensuring diseases are monitored effectively and enhancing the understanding of disease dynamics

When to Investigate Outbreaks

• Investigate outbreaks when the severity of the disease is high, as indicated by the impact on health or mortality
• An example of high severity is '20 students from a veterinary medicine course vomiting'
• Outbreaks with high transmissibility require urgent investigation to prevent further spread, especially diseases that can affect both animals and humans
• Investigation is crucial when there is a lack of knowledge regarding the disease, including its cause and mode of transmission, to ensure public safety
• Continuous exposure to the disease increases the need for investigation, particularly in situations where there is ongoing risk to health
• An example of continuous exposure is cases of '1 case of Ebola in Portugal'

Steps in Outbreak Investigation

• Creating a multidisciplinary team to address the outbreak including:
  • Veterinarians
  • Epidemiologists
  • Field technicians
  • Public health officials Ensure comprehensive responses
• Verify the outbreak by assessing temporal, population, and geographic factors.
• An epidemic is defined as an 'increase in the number of cases of a disease - in excess relative to what is expected
• Define clear parameters for cases, including individual characteristics, symptoms, location, and timeline
• Foot-and-mouth disease may include pigs with fever and vesicles
• Continue monitoring the disease to assess spread and control measures.
• Communicate with health authorities to evaluate intervention effectiveness

Forming an Investigation Team

• Veterinarians provide expertise on animal health, disease symptoms, and potential zoonotic transmissions
• Epidemiologists analyze data related to disease spread, identify patterns, and help formulate hypotheses regarding outbreak dynamics
• Laboratory personnel conduct diagnostic tests, confirming disease causative agents, and providing critical lab results

Confirming an Outbreak

• An epidemic is defined as an increase in the number of cases of a disease occurring in excess of what is normally expected in a specific area or among a specific group of people
• Epidemics can be identified by examining the temporal patterns of disease occurrence, such as outbreaks that peak at specific times, indicating a surge in cases.
• Epidemics can also be geographically defined, with certain areas experiencing higher incidence rates of disease, necessitating targeted investigation

Diagnosis Confirmation

• Review medical records to gather clinical history and symptoms reported
• Analyze laboratory results for confirmation of the disease causative agent
• Collect and evaluate epidemiological data to understand disease spread and context

Defining a Case

• A case is defined by identifying the affected individual
• In foot-and-mouth disease, a case may include 'pigs exhibiting fever and vesicles in the mouth and around the feet (lameness, hypersalivation)
• This specificity helps in tracking disease spread
• Determining the geographic context is crucial and aids in understanding how and where the disease spreads
• Establishing the timeline of the outbreak is essential for assessing disease spread and implementing control measures
• Defining the incubation period for the disease is important for tracking exposure and helps in identifying potential exposure sources and timing of interventions
• The incubation period for foot-and-mouth disease is 2 to 14 days

Hypothesis Testing in Investigations

• Cohort studies involve including all individuals eligible to become ill, allowing for the measurement of association through relative risk and systematically observes the outcomes of a group over time
• In case-control studies, researchers evaluate risk factors by comparing individuals who have the disease (cases) with those who do not (controls) and is useful when the population at risk is not clearly defined
• Attack rates are calculated as the number of cases exposed divided by the number of susceptible individuals exposed and helps in understanding the extent of disease spread

Implementing Control Measures

• Quarantine involves isolating affected animals to prevent the spread of disease to healthy populations and is crucial during outbreaks to contain the infection
• Vaccination is a proactive approach to immunize animals against specific diseases, reducing the risk of outbreaks
• Vaccination can be implemented during a Rabies outbreak
• Culling involves the removal of infected or at-risk animals to control the spread of disease and is often a last resort during severe outbreaks

Communicating Results

• Clear communication ensures all stakeholders are informed about the outbreak and its implications
• Promotes transparency and trust within the community regarding health risks and preventive measures
• Facilitates timely decision-making and implementation of control measures to prevent further spread of the disease
• Oral presentations allow for direct interaction with the audience, facilitating immediate feedback and clarification
• Written reports provide a detailed account of the investigation, including findings, methodologies, and recommendations for future actions
• Visual aids such as charts and graphs enhance understanding and retention of complex data during presentations
• Collaboration wwith multidisciplinary teams can improve communication effectiveness and ensure all relevant information is conveyed

Challenges in Outbreak Investigation

• Public Pressure to find the cause of an outbreak quickly, which can lead to rushed conclusions
• Small Sample Size that makes it difficult to draw reliable conclusions
• Biases in Data Collection such as memory bias and information bias that can affect the accuracy of the data collected during the investigation
• Complexity of Cases with some outbreaks involving multiple species or pathogens, adding complexity to the investigation and control measures

Historical context of Field Epidemiology

• 2001 FMD Outbreak UK saw rapid response by field epidemiologists, who controlled the spread using tracing and culling strategies
• Field epidemiology has been critical in monitoring wild birds and implementing biosecurity measures on farms to prevent transmission with Avian influenza
• Field epidemiologists track African Swine Fever's spread, advising on quarantine measures and developing vaccination strategies

Surveillance Systems

• Passive surveillance involves routine reporting of disease cases by health facilities, relying on existing healthcare infrastructure
• Active surveillance involves proactive data collection through field visits and surveys aimed at detecting emerging diseases, like monitoring wildlife for signs of disease
• Sentinel surveillance involves utilizing specific animal populations, like poultry farms, as indicators for disease presence, helping in early detection of diseases such as Avian Influenza

Risk Assessment in Outbreaks

• Risk assessment involves identifying and evaluating factors such as animal density, movement patterns, and environmental conditions that contribute to disease outbreaks
• Geographic Information Systems (GIS) are utilized to map disease spread, analyze spatial data, and visualize outbreak patterns, aiding in understanding risk factors
• Risk matrices help assess the likelihood and impact of potential outbreaks by categorizing risks based on severity and probability, providing a structured approach to decision-making
• Effective risk assessment enhances preparedness and response strategies by informing stakeholders about potential threats and necessary control measures

Components of Preparedness Plans

• Resource Allocation involves identifying and distributing necessary resources such as vaccines, medical supplies, and personnel to effectively respond to outbreaks
• Training Programs involves implementing training for staff and stakeholders on outbreak management, response protocols, and effective communication
• Communication Strategies involves establishing clear communication channels with stakeholders, to ensure timely information dissemination
• Contingency Plans involves developing specific plans outlining actions to take during an outbreak, including vaccination strategies and quarantine protocols

Other Key Facts

• During a Brucellosis outbreak in cattle, steps were taken to conduct an epidemiological investigation to establish the source which involved:

  • Collecting data from affected farms
  • Interviewing farmers about animal movements
  • Reviewing veterinary records

• Laboratory testing was performed on blood samples to confirm Brucellosis cases

• Control measures that were implemented included:

  • Quarantining the infected herds
  • Conducting mass vaccinations in at-risk populations
  • Educating farmers about biosecurity practices to prevent further spread Follow-up testing and monitoring ensured that the outbreak was effectively controlled and that no new cases emerged

• In response to an Avian Influenza outbreak, immediate actions were taken to contain the virus

• Data collection involved extensive surveillance in affected areas/Data collection involved:

  • Monitoring bird populations and reporting suspected cases by farmers
  • Laboratory analysis confirmed the strain and guided intervention strategies

• Intervention strategies included:

  • Culling infected flocks
  • Implementing strict biosecurity measures
  • Vaccinating at-risk populations

• Communication with stakeholders ensured transparency and compliance with control measures, significantly reducing the spread of the virus

Communication Strategies During Outbreaks

• Stakeholder Engagement means that effective communication with farmers, veterinarians, and the public is essential during outbreaks and regular updates and transparent information build trust among stakeholders and foster collaboration
• Managing Misinformation by Addressing rumors swiftly and utilizing social media platforms to provide accurate information Creating a FAQ section on official websites clarifies common concerns
• Importance of Clear Communication ensures all stakeholders are informed about the outbreak and its implications and promotes transparency and trust within the community regarding health risks and preventive measures

Post-Outbreak Surveillance

• Methods of Post-Outbreak Surveillance includes regular health checks of animal populations to monitor ongoing health status
  • Laboratory testing for potential resurgence of diseases previously contained
  • Monitoring animal movements to identify new cases of infection through tracking systems
• Importance of Post-Outbreak Surveillance:
  • Detects any resurgence of a disease after control measures are implemented
  • Ensures the health of the animal population and protects public health from potential outbreaks
  • Aids in identifying the effectiveness of control measures and informs future strategies

Understanding Zoonotic Diseases

• Zoonotic diseases are infections that can be transmitted from animals to humans
• Common examples include Rabies, Brucellosis, and Avian Influenza diseases
• Zoonotic diseases can originate from wildlife, livestock, or domesticated animals
• Zoonotic diseases pose a significant risk to human health globally and effective control and prevention strategies are essential to protect public health

The One Health Approach

• The One Health approach recognizes that the health of humans, animals, and ecosystems are interconnected and influence one another
• It emphasizes collaboration across multiple disciplines, including veterinary medicine, human health, and environmental science, to tackle health challenges effectively
• It integrates efforts to control zoonotic diseases, such as rabies and Avian Influenza and aims to improve overall health outcomes for all species

Ethical Considerations in Outbreak Management

• Animal Welfare Considerations:
  • Culling should only be a last resort after other measures are exhausted
  • Ensuring humane treatment during culling processes is essential
  • Ethical frameworks can guide decisions to minimize suffering
• Ethical Implications of Control Measures:
  • Culling raises ethical concerns regarding the value of animal life
  • Balancing disease control with humane treatment of animals is crucial
  • Transparency in decision-making fosters public trust

Technological Advances in Epidemiology

• GIS in Epidemiology enables tracking of disease spread in real-time
• GIS tools assist in analyzing spatial data and visualizing outbreak patterns and technologies help inform targeted response strategies based on geographic data
• Data Analysis Tools:
  • Advanced statistical software and machine learning algorithms analyze large datasets effectively
  • Data analysis tools identify trends and associations in disease outbreaks, aiding in swift decision-making
  • Real-time data processing enhances the ability to predict and manage potential outbreaks