🚑Contemporary Health Issues Unit 2 – Global Health Challenges & Epidemics

Key Global Health Challenges

• Infectious diseases continue to be a major threat to global health causing millions of deaths annually (malaria, tuberculosis, HIV/AIDS)
• Non-communicable diseases are on the rise globally due to lifestyle changes and aging populations (cardiovascular diseases, cancers, diabetes)
  • Account for over 70% of all deaths worldwide
  • Pose significant economic burdens on healthcare systems
• Health inequities persist between and within countries with vulnerable populations facing disproportionate disease burdens
• Antimicrobial resistance is making previously treatable infections harder to combat as pathogens evolve resistance to antibiotics
• Environmental factors like climate change, pollution, and habitat destruction are altering disease patterns and creating new health risks
• Inadequate access to essential health services, clean water, and sanitation in low-income countries contributes to preventable illnesses
• Mental health disorders are often overlooked but cause substantial disability and reduced quality of life worldwide

Understanding Epidemics

• Epidemics are the rapid spread of infectious diseases to a large number of people in a short period of time
• Pandemics are epidemics that have spread over multiple countries or continents
• Epidemiology is the study of the distribution and determinants of health-related states or events in specified populations
  • Aims to control health problems through surveillance, investigation, and intervention
• Key concepts in epidemiology include incidence (new cases), prevalence (existing cases), morbidity (illness), and mortality (death)
• Epidemic curves are visual representations of the number of cases over time and can help identify the source and pattern of spread
• Herd immunity occurs when a significant portion of a population becomes immune providing indirect protection to non-immune individuals
• Basic reproduction number (R0) represents the average number of new infections caused by one infected individual in a fully susceptible population
  • R0 > 1 indicates a disease will continue to spread; R0 < 1 indicates it will eventually die out

Major Historical Epidemics

• The Black Death (bubonic plague) killed an estimated 30-50% of Europe's population in the 14th century
• The 1918 influenza pandemic infected one-third of the world's population and caused an estimated 50 million deaths
  • Spread rapidly due to troop movements during World War I
• Smallpox devastated indigenous populations in the Americas during European colonization in the 15th-17th centuries
• The HIV/AIDS pandemic has claimed over 36 million lives since its emergence in the 1980s
  • Disproportionately affects sub-Saharan Africa which accounts for 67% of global HIV infections
• Cholera pandemics in the 19th century spread from India to Europe, Africa, and the Americas through trade routes and shipping
• The 2014-2016 Ebola epidemic in West Africa was the largest and most complex Ebola outbreak since the virus was discovered
• The COVID-19 pandemic has caused over 6 million deaths globally since its emergence in late 2019

Current Global Health Threats

• Emerging infectious diseases are those that have newly appeared in a population or have existed but are rapidly increasing in incidence or geographic range (Zika virus, SARS-CoV-2)
• Re-emerging infectious diseases are those that were once a major health problem globally or in a particular country and are again becoming a health problem for a significant proportion of the population (measles, drug-resistant tuberculosis)
• Neglected tropical diseases affect over 1 billion people in low-income countries causing significant morbidity and disability (dengue, schistosomiasis, leishmaniasis)
• Foodborne illnesses cause an estimated 600 million cases and 420,000 deaths annually with a disproportionate burden in low- and middle-income countries
• Antimicrobial resistance is a growing threat making common infections harder to treat and increasing the risk of disease spread, severe illness, and death
  • Overuse and misuse of antimicrobials in humans, animals, and agriculture contributes to resistance
• Vaccine hesitancy and misinformation can lead to disease outbreaks even in countries where vaccines are readily available (measles resurgence)
• Health consequences of climate change include the spread of vector-borne diseases, food and water insecurity, and population displacement

Factors Influencing Disease Spread

• Population density and urbanization facilitate the rapid spread of infectious diseases through increased contact rates
• Human mobility through travel and migration can introduce pathogens to new areas and susceptible populations
• Globalization of trade and food supply chains can contribute to the international spread of foodborne illnesses
• Environmental factors like temperature, humidity, and rainfall can affect the survival and transmission of certain pathogens (influenza, cholera)
• Social determinants of health such as poverty, education, and access to healthcare can influence individual and population susceptibility to diseases
• Cultural practices and beliefs can impact health behaviors and disease transmission (burial practices during Ebola outbreaks)
• Zoonotic diseases are those transmitted from animals to humans and are influenced by human-animal interactions and environmental changes (Nipah virus, avian influenza)
  • Over 60% of emerging infectious diseases are zoonotic in origin

Prevention and Control Strategies

• Surveillance systems are essential for detecting and monitoring disease outbreaks and guiding public health responses
  • Include ongoing systematic collection, analysis, and interpretation of health data
• Vaccination is one of the most effective ways to prevent infectious diseases by providing individual and herd immunity
  • Challenges include vaccine development, distribution, and addressing vaccine hesitancy
• Infection control measures like hand hygiene, personal protective equipment, and isolation of infected individuals can limit disease spread in healthcare settings and communities
• Risk communication and community engagement are critical for promoting health behaviors and building trust during outbreaks
• Strengthening health systems and increasing access to primary healthcare services can improve disease prevention, detection, and response capacities
• One Health approach recognizes the interconnection between the health of people, animals, and the environment and promotes collaborative efforts across sectors
• International Health Regulations provide a legal framework for preventing and responding to public health risks that have the potential to cross borders

International Health Organizations

• The World Health Organization (WHO) is the leading international agency for global health
  • Responsibilities include setting norms and standards, providing technical support, and coordinating responses to health emergencies
• The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States but also supports global health efforts through partnerships and outbreak response
• The Global Fund is an international financing institution that invests in programs to fight AIDS, tuberculosis, and malaria in low- and middle-income countries
• Gavi, the Vaccine Alliance, is a public-private partnership that aims to increase access to immunization in poor countries
• The Coalition for Epidemic Preparedness Innovations (CEPI) is a global partnership launched in 2017 to develop vaccines to stop future epidemics
• Médecins Sans Frontières (MSF) is an international humanitarian organization that provides medical assistance to people affected by conflict, epidemics, disasters, or exclusion from healthcare
• UNICEF works in over 190 countries to save children's lives, defend their rights, and help them fulfill their potential, including through health and immunization programs

Future Trends and Emerging Issues

• Population growth and demographic changes will strain health systems and resources, particularly in low- and middle-income countries
• Urbanization and globalization will continue to facilitate the rapid spread of infectious diseases across borders
• Climate change is expected to alter the geographic range and seasonality of vector-borne diseases and increase the frequency of extreme weather events that can disrupt health services
• Technological advances in disease surveillance, diagnostics, and vaccine development may improve outbreak detection and response
  • Innovations include real-time data collection, point-of-care testing, and mRNA vaccines
• Increasing antimicrobial resistance will require the development of new antibiotics and the promotion of responsible use in human and animal health
• Health equity and social justice will be critical considerations in addressing the disproportionate burden of diseases on marginalized populations
• Strengthening global health governance and collaboration will be essential for preparing for and responding to future health threats that transcend national borders
• Investing in health systems and workforce capacity building can improve resilience to health emergencies and progress towards universal health coverage