13.3 Infectious Disease Prevention and Control

Public Health Surveillance

Public health surveillance is the “ongoing, systematic collection, analysis, and interpretation of health-related data essential to planning, implementation, and evaluation of public health practice” (CDC, 2018b, para 1) and more specifically refers to the monitoring of communicable diseases, noncommunicable diseases, injuries, and risk factors for these health outcomes in a population. Using data to monitor health problems is a key function of public health surveillance as it assists in prevention or control. Public health officials can use data to prioritize planning prevention and control programs (CDC, 2012).

Although numerous health issues affect global populations, many are neither urgent nor directly threaten health. Some health issues, such as breast cancer, are persistent and chronic, with a stable incidence and prevalence in the community. Therefore, the first step in public health surveillance is to identify which health problems to monitor. Selecting and prioritizing health problems for surveillance involves identifying issues that impact public health. The second step relates to the incidence, prevalence, severity, mortality, socioeconomic impact, and communicability of the disease or problem and the ability to prevent or control it. In general, communicable diseases are more commonly under surveillance, given their possibility of causing an increased threat to public health. Within the United States, surveillance begins at local and state-level public health departments as each state sets local laws for diseases and conditions that must be reported. Local health departments work with laboratories, hospitals, and health care providers to obtain information on reportable diseases and then convey it to the state health department. The state health department uses the data to locate the source of a potential outbreak to prevent its spread and sometimes will involve the CDC, depending on the scope of the issue (CDC, 2022aj).

Local and state health departments are also responsible for notifying the CDC about agreed-upon notifiable diseases and health conditions. The Council of State and Territorial Epidemiologists and the CDC identify this list together, and states voluntarily inform the CDC when an individual meets the criteria to become a case. The CDC then uses this data to monitor and alert communities about potential health threats (CDC, 2022aj). The CDC also partners with the WHO through the Global Outbreak Alert and Response Network (Christensen et al., 2021).

The CDC conducts public health surveillance through the National Notifiable Diseases Surveillance System (NNDSS) to track reportable and notifiable diseases and conditions with the assistance of local health departments. Currently, approximately 120 diseases are under NNDSS surveillance, including communicable and noncommunicable diseases and bioterrorism agents, with almost 2.7 million disease cases reported each year (CDC, 2022aj).

Each time a public health agency collects information about an individual diagnosed with a health condition that could threaten others, it is called case surveillance. This case surveillance is at the foundation of public health practice (CDC, 2022an). Recall John Snow’s cholera outbreak investigation in London in Epidemiology for Informing Population/Community Health Decisions. Case surveillance usually includes infectious diseases, such as COVID-19, or foodborne outbreaks, like E. coli. However, some noninfectious conditions are also surveilled, such as lead poisoning (CDC, 2022aj). Health departments notify the CDC to report instances of an estimated 120 diseases and conditions monitored under NNDSS surveillance. Case surveillance captures information about the population affected, the geographical area involved, and the course of illness and treatment that public health professionals can use to inform prevention and control efforts (CDC, 2022aj).

A surveillance case definition is a set of criteria used to define a disease for public health surveillance. Case definitions include clinical criteria such as expected signs or symptoms and often have restrictions by time, place, and person, especially in the setting of potential health threats to others. This enables public health officials to be consistent in case classifications and counting across states. Surveillance case definitions are not the criteria that health care providers use to diagnose, manage, and treat conditions in the clinical setting; they are used for data reporting and tracking purposes only (CDC, 2022ah). Surveillance data are also included in the CDC’s Morbidity and Mortality Weekly Report (MMWR) series. This publication is the agency’s main dissemination of authoritative, useful public health information and recommendations. MMWR is targeted toward scientists, health professionals, epidemiologists, and public health professionals, including public health and community health nurses (CDC, 2023k).

Outbreak Investigation

A disease outbreak refers to more cases of a certain disease or health condition than expected. Gathering surveillance data is one method of establishing the existence of an outbreak. This process can occur at the local or state health department and in hospital facilities looking to identify any hospital-acquired infections. Similarly, the CDC regularly reviews surveillance data and laboratory patterns of disease-causing organisms to detect clusters of illness. Another way to detect an outbreak is when a health care provider alerts the local health department about unusual cases—unusual due to the frequency or type of condition. An example is the 1999 WNV infection, which was discovered after a New York City health department received a call from a physician who had recently evaluated two clients with encephalitis (CDC, 2012, pp. 6–2). Community members may also call local health departments to report abnormal clusters of illness. An example is foodborne-related illness where an individual calls the health department and reports that seven of their friends are ill with similar symptoms after eating at the same restaurant. Another example would be a concerned community member reporting a cancer cluster in their neighborhood. A health department’s decision to investigate a potential outbreak depends on many factors, such as illness severity, number of cases, mode of transmission, and availability of prevention and control measures (Figure 13.6). Typically, the more individuals affected or the more serious the illness, the greater the likelihood of an outbreak investigation with the ultimate goal to assist in disease prevention and control (CDC, 2012).

Figure 13.6 A team screens for disease by taking a nasal sample. (credit: by Kaylianna Genier/U.S. Navy/Flickr, Public Domain)

Surveillance for and Prevention of Foodborne Diseases

Prevention of foodborne diseases requires careful oversight and monitoring along the food supply chain. The CDC works collaboratively with the U.S. Department of Agriculture (USDA), the Food and Drug Administration (FDA), and local and state public health departments to ensure food safety along the steps in the food chain. This work involves identifying foodborne illness, investigating multistate foodborne disease outbreaks, providing education to prevent outbreaks, and implementing systems to better address, detect, and stop outbreaks (CDC, 2022b). The CDC helps to track and investigate foodborne illnesses through the following surveillance systems:

• PulseNet
• Foodborne Diseases Active Surveillance Network (FoodNet FAST)
• System for Enteric Disease Response, Investigation, and Coordination (SEDRIC)
• Foodborne Disease Outbreak Surveillance System (FDOSS)

Whole genome sequencing (WGS) is an advanced technology that assists epidemiologists in finding foodborne outbreaks. WGS data helps scientists determine DNA similarities in strains of pathogens, indicating they come from the same source and allowing the CDC and its partners to detect outbreaks more quickly and to solve outbreaks while they are still small. When PulseNet scientists determine the same strain causes a group of illnesses, disease detectives can investigate the illness to determine if they came from the same food or food source (Figure 13.7). This has improved the ability to link foodborne illnesses and detect outbreaks (CDC, 2022b).

The CDC investigates multistate foodborne outbreaks using a seven-step process (CDC, 2022ag):

1. Detect a possible outbreak through data surveillance.
2. Find individuals included in the outbreak and look for additional ill individuals.
3. Generate hypotheses by interviewing ill individuals.
4. Test hypotheses by comparing what ill individuals ate to what well people of a similar group ate.
5. Solve by confirming the contaminated food using epidemiologic and lab information to identify the contamination point.
6. Control and stop the outbreak by recalling the food, cleaning or closing facilities, and educating those involved.
7. Decide the outbreak is over when illness ends and the contaminated foods are no longer available.

Figure 13.7 A disease detective works in the community to interview and gather data on a disease outbreak. (credit: “Disease Detectives in Guatemala” by CDC/Flickr, CC BY 2.0)

Nurse’s Role During an Infectious Disease Outbreak

Nursing plays a distinct role in pandemics and other infectious disease outbreaks. As part of the three core functions of public health nursing, nurses are involved with assessment in terms of epidemiological surveillance and detection, such as contact tracing. A school nurse working in New York City is credited with first observing and notifying the CDC about the 2009 H1N1 flu pandemic (National Academies of Sciences, Engineering, and Medicine [NASEM], 2021). During the COVID-19 pandemic, nurses conducted most contact tracing at the local board of health, at the state level, and in school districts. Public health nurses assist with coordinating and implementing disaster plans at the local and state levels, an aspect of policy development. Preparedness is a multidisciplinary effort to understand a health care system’s capacity in advance of a public health emergency, including workforce capacity, access to personal protective equipment, and medical supplies, an aspect of assurance (NASEM, 2021).

During an evolving infectious disease outbreak, the nursing role may shift as health care shifts from routine care to public health care, emergency preparedness, and disaster response. Nurses working in various practice settings serve on the front line of public health emergencies, assisting individuals and communities through a crisis. Promoting health and well-being is one of the essential roles of nursing. Nurses engage and connect with individuals and communities to ensure they have what they need to be healthy (NASEM, 2021).

As the COVID-19 pandemic revealed, this engagement, ability, and willingness to respond to public health crises takes a toll on nursing; during that pandemic, many nurses reported feeling unsafe, unsupported, and unprepared, resulting in a profound mental health burden (NASEM, 2021). The COVID-19 pandemic required nurses to take on multiple roles: for example, outpatient endoscopy nurses were asked to care for medical-surgical clients, and non–critical care nurses were asked to care for critically ill clients. Nurses also provided end-of-life care and served as a means of communication between dying or ill clients and their families. This most recent pandemic has illustrated the vital importance of protecting nurses’ well-being and mental health so that they can respond to disasters effectively and safely (NASEM, 2021).

Nurses also have a role within the health promotion and disease prevention framework along the three levels of prevention. Within an infectious disease outbreak, the public health nurse plays a vital role in primary, secondary, and tertiary prevention (Table 13.13).