Emerging Infectious Diseases: Videos & Practice Problems

Emerging infectious diseases are novel or rapidly spreading pathogens requiring new control strategies, exemplified by SARS-CoV-2. Reemerging diseases like tuberculosis resurface after prior control, often due to factors such as microbial evolution, antibiotic misuse, population growth, climate change, and complacency. These factors influence pathogen adaptation, transmission, and resistance, highlighting the importance of vigilance, vaccination, and public health measures. Understanding these dynamics aids in managing infectious diseases, emphasizing the role of epidemiology, microbial resistance, and societal changes in disease prevalence and control.

Emerging & Re-Emerging Infectious Diseases

Emerging infectious diseases are those that are either completely new or have recently increased in incidence or geographic spread, presenting new challenges for public health. These diseases, such as SARS-CoV-2 (the virus responsible for COVID-19, first identified in late 2019), often require novel strategies and tools for control due to their unpredictable behavior and associated uncertainties. The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) play crucial roles in monitoring and responding to these emerging threats on national and global scales.

In contrast, reemerging infectious diseases are illnesses that were once controlled or declining but have begun to resurface, causing new outbreaks or epidemics. Tuberculosis (TB), caused by Mycobacterium tuberculosis, exemplifies a reemerging disease, as its cases have been rising again after previous successful control efforts. Since reemerging diseases are familiar, existing treatment and control methods are typically effective, resulting in fewer uncertainties and risks compared to emerging diseases. However, their resurgence highlights the importance of sustained vigilance and prevention efforts to avoid complacency.

Understanding the distinction between emerging and reemerging infectious diseases is vital for effective public health responses. Emerging diseases demand innovative approaches due to their novel nature or changing patterns, while reemerging diseases remind us that past successes in disease control must be maintained to prevent resurgence. This knowledge supports the development of targeted strategies to mitigate the impact of infectious diseases worldwide.

Emerging Infectious Diseases Example 1

Emerging infectious diseases are defined as previously unknown illnesses or diseases that have recently increased in incidence or geographic distribution. These diseases exhibit new patterns of behavior that were not observed in the past. In contrast, reemerging infectious diseases are those that were once under control with declining case numbers but have now resurged and become prevalent again. This resurgence indicates a comeback of diseases that had been previously managed effectively.

Several factors contribute to the emergence of infectious diseases. These include novel pathogens, genetic mutations, increased human-animal interactions, globalization, and environmental changes. On the other hand, reemerging infectious diseases often arise due to lapses in control measures, the development of antimicrobial resistance, and adaptations by pathogens that allow them to evade previous interventions.

Examples of emerging infectious diseases include COVID-19, HIV/AIDS during the 1980s, and Ebola. Meanwhile, tuberculosis, cholera, measles, and dengue fever are notable examples of reemerging infectious diseases.

From a public health perspective, emerging infectious diseases pose significant challenges because their appearance and behavior are difficult to predict. They often necessitate the development of new surveillance systems and research efforts to understand and control them effectively. Conversely, reemerging infectious diseases, having been controlled before, may initially be addressed using previously successful strategies. However, if these methods prove ineffective due to changes such as pathogen resistance, renewed or improved interventions, including the development of new vaccines, become essential.

Which option is the least effective strategy to control an outbreak of an emerging infectious disease?

• A. Having scientists study the structure of the pathogen so they can work on producing a vaccine.
• B. Conducting public awareness campaigns to educate people on how to prevent the spread of the disease.
• C. Restricting travel to and from the area that experienced the outbreak to contain the disease.
• D. Focusing solely on treating symptomatic individuals and not conducting wider research on the disease.

Answer: (D)

Factors Contributing to Emerging & Re-Emerging Infectious Diseases

Emerging and reemerging infectious diseases are influenced by several interconnected factors that shape how pathogens evolve and spread. One key factor is microbe evolution, where microorganisms undergo genetic changes over time, potentially acquiring new pathogenic traits. This evolutionary process can lead to the development of antibiotic resistance, making previously effective treatments less reliable. Understanding microbial adaptation is crucial for managing infectious diseases effectively.

Population growth and overcrowding contribute significantly to disease emergence by creating unsanitary conditions that facilitate pathogen transmission. As more people live in close proximity, the likelihood of exposure to infectious agents increases, promoting outbreaks. Similarly, modern food production and distribution systems can inadvertently spread pathogens through cross-contaminated food, leading to widespread disease outbreaks.

The misuse of antibiotics disrupts the balance of normal microbiota, which can allow opportunistic pathogens to thrive and cause infections. This misuse accelerates the development of resistant strains, complicating treatment efforts. Additionally, climate change alters environmental conditions such as temperature and humidity, affecting the survival and distribution of pathogens and their vectors. For example, rising temperatures can expand the habitat of mosquitoes, vectors for diseases like Zika virus, increasing the risk of transmission in new regions.

Complacency in public health measures, such as reduced vaccination rates due to a false sense of security, can lead to the resurgence of controllable diseases. The reemergence of measles in under-vaccinated communities exemplifies how lapses in prevention strategies can reverse previous gains in disease control.

Finally, societal changes such as increased international travel and the widespread use of daycare centers contribute to the global spread and reemergence of infectious diseases. Travel facilitates rapid movement of pathogens across continents, while environments like daycare centers, where hygiene may be suboptimal, provide opportunities for disease transmission among vulnerable populations.

By understanding these factors—microbial evolution, population dynamics, food safety, antibiotic stewardship, climate impacts, public health vigilance, and societal behaviors—we can better anticipate and respond to the challenges posed by emerging and reemerging infectious diseases.

How would you expect global warming to affect the spread of vector-borne diseases?

• A. Many vectors of disease are insects which thrive in warmer temperatures, thus increasing prevalence of disease.
• B. Global warming increases the geographical range of vector-borne diseases that thrive in warm climates.
• C. Global warming lengthens the “warm” seasons when vector-borne diseases are most prevalent.
• D. All of the above.

Answer: (D)

Here’s what students ask on this topic:

What is the difference between emerging and reemerging infectious diseases?

Emerging infectious diseases are either completely new or have recently increased in incidence or geographic spread, requiring new control strategies. An example is SARS-CoV-2, the virus causing COVID-19, first identified in 2019. These diseases often present uncertainties and risks because they behave in ways not seen before. In contrast, reemerging infectious diseases are those that were previously controlled but have resurfaced, such as tuberculosis (TB). Since we are familiar with reemerging diseases, existing treatment and control methods are usually effective, but vigilance is necessary to prevent outbreaks due to factors like complacency or microbial evolution.

What factors contribute to the emergence and reemergence of infectious diseases?

Several factors contribute to emerging and reemerging infectious diseases. Microbe evolution allows pathogens to develop new traits or antibiotic resistance. Population increase and overcrowding create unsanitary conditions that facilitate disease spread. Food production and distribution can lead to outbreaks through cross-contamination. Misuse of antibiotics disrupts normal microbiota, favoring opportunistic pathogens. Climate change affects pathogen survival and vector distribution, such as mosquitoes expanding into new areas. Complacency leads to decreased vaccination and public awareness, allowing controlled diseases to resurface. Lastly, societal changes like increased international travel and daycare use promote disease transmission.

How does microbial evolution impact infectious disease control?

Microbial evolution plays a critical role in infectious disease control by enabling pathogens to adapt and develop new characteristics, such as antibiotic resistance. This evolution can render previously effective treatments less effective or ineffective, complicating disease management. For example, bacteria may acquire resistance genes through natural selection, making antibiotics less reliable. This necessitates continuous monitoring of microbial changes and the development of new drugs or treatment strategies. Understanding microbial evolution helps public health officials anticipate challenges and adapt control measures to prevent the spread of resistant or more virulent strains.

Why is complacency a risk factor for reemerging infectious diseases?

Complacency occurs when people assume that a disease is no longer a threat and reduce preventive measures like vaccination and public health vigilance. This can lead to decreased immunity in the population, creating conditions for controlled diseases to reemerge. For example, measles was nearly eliminated in the United States by 2000, but reduced vaccination rates due to complacency have caused outbreaks when infected travelers introduce the virus to under-vaccinated communities. Complacency undermines disease control efforts and highlights the importance of sustained public awareness and vaccination programs to prevent the resurgence of infectious diseases.

How does climate change influence the spread of infectious diseases?

Climate change affects infectious disease spread by altering environmental conditions that influence pathogen survival and vector populations. For instance, rising temperatures and changes in humidity can expand the habitats of vectors like mosquitoes, which transmit diseases such as Zika virus and malaria. This expansion allows diseases to emerge in new geographic areas where populations may have little immunity. Additionally, climate change can disrupt ecosystems and human behaviors, increasing contact with pathogens. Understanding these impacts is crucial for predicting disease patterns and implementing effective public health interventions in a changing climate.