Topic 4.2 Emerging Infectious Diseases, Zoonoses and Global Health Security

Infectious diseases continue to pose one of the greatest threats to global health, with new pathogens emerging and familiar diseases re-emerging as a result of environmental change, global travel, urbanisation, climate change and increasing interactions between people, animals and ecosystems. Over the past several decades, outbreaks such as Severe Acute Respiratory Syndrome (SARS), Middle East Respiratory Syndrome (MERS), Ebola virus disease, highly pathogenic avian influenza, COVID-19 and Mpox have demonstrated how rapidly infectious diseases can spread across local, national and international borders. These events have reinforced the importance of preparedness, surveillance, interdisciplinary collaboration and evidence-based infection prevention across all healthcare professions.

Occupational Therapists (OTs) may not diagnose or treat infectious diseases; however, they play an important role in recognising infection risks, adapting service delivery, educating clients and maintaining continuity of care during periods of increased infectious disease activity. Occupational therapy frequently occurs within hospitals, rehabilitation services, residential aged care, schools, disability services, workplaces and community settings, all of which may be affected by emerging infectious diseases. Understanding how these diseases arise and spread enables Occupational Therapists to make informed clinical decisions that protect clients, colleagues, assistance animals and the wider community.

Emerging infectious diseases are closely linked to the One Health framework. Approximately 60% of known human infectious diseases and around 75% of emerging infectious diseases originate in animals or have an animal reservoir. Human health cannot therefore be considered independently of animal health or environmental health. Changes in land use, biodiversity loss, climate change, wildlife trade, intensive agriculture and global movement of people and animals all influence the emergence and spread of infectious diseases. Occupational Therapists working alongside assistance animals should understand these broader influences to appreciate how local clinical practice contributes to global health security.

This topic explores emerging and re-emerging infectious diseases, zoonotic disease emergence, antimicrobial resistance, global health security and the Occupational Therapist’s role in supporting resilient, evidence-informed infection prevention within an increasingly interconnected world.

Emerging and Re-emerging Infectious Diseases

Emerging infectious diseases are diseases that have:

• recently appeared within a population
• significantly increased in incidence
• expanded into new geographic areas
• evolved into new variants or strains.

Re-emerging infectious diseases are previously recognised diseases that have returned after a period of decline or control.

Examples include:

Emerging diseases

• COVID-19
• Mpox
• SARS
• MERS
• Hendra virus
• Nipah virus

Re-emerging diseases

• measles
• tuberculosis
• pertussis
• dengue fever
• cholera.

The distinction between emerging and re-emerging diseases is important because prevention strategies may differ depending on the underlying causes of disease transmission.

Why Are Emerging Diseases Increasing?

Disease emergence is rarely caused by a single factor. Instead, multiple environmental, biological and social influences interact to create opportunities for pathogens to spread.

Key drivers include:

• global travel and tourism
• international trade
• urbanisation
• climate change
• biodiversity loss
• habitat destruction
• population growth
• increased human-animal interaction
• changing agricultural practices
• antimicrobial resistance.

These factors increase opportunities for microorganisms to cross species barriers, adapt to new hosts and spread rapidly through interconnected populations.

Zoonotic Disease Emergence

As discussed in Module 1, zoonotic diseases are infections naturally transmitted between animals and humans.

Many emerging infectious diseases originate in wildlife before moving into domestic animals or directly into people.

Examples include:

• Hendra virus (fruit bats → horses → humans)
• avian influenza (wild birds → poultry → humans)
• Nipah virus (fruit bats → pigs → humans)
• SARS-related coronaviruses (wildlife reservoirs)
• COVID-19 (animal origin remains under investigation)
• Mpox (animal reservoirs in endemic regions).

The emergence of these diseases highlights the importance of surveillance, veterinary medicine, environmental conservation and interdisciplinary collaboration.

Occupational Therapists are unlikely to encounter most emerging zoonotic diseases directly; however, understanding their origins reinforces the importance of infection prevention, One Health and evidence-based practice.

Climate Change and Infectious Disease

Climate change is increasingly recognised as an important driver of infectious disease emergence.

Changing environmental conditions influence:

• vector distribution
• wildlife movement
• water quality
• food production
• ecosystem stability
• extreme weather events.

These changes may increase the geographic range of diseases transmitted by:

• mosquitoes
• ticks
• other arthropod vectors
• contaminated food
• contaminated water.

Climate-related disasters may also disrupt healthcare systems and increase the risk of infectious disease outbreaks through population displacement, overcrowding and reduced sanitation.

Occupational Therapists should recognise that environmental health is an important determinant of both infection prevention and occupational participation.

Global Health Security

Global health security refers to the collective efforts of countries, organisations and communities to prevent, detect and respond to infectious disease threats before they become widespread public health emergencies.

Key components include:

• surveillance systems
• laboratory capacity
• rapid reporting
• emergency preparedness
• vaccination programs
• public health communication
• international collaboration
• workforce education.

No country can achieve health security in isolation. Infectious diseases do not recognise national borders, making international cooperation essential.

Surveillance and Early Detection

Disease surveillance involves the systematic collection, analysis and interpretation of health information to identify infectious disease trends.

Surveillance supports:

• early outbreak detection
• monitoring disease spread
• evaluating interventions
• identifying emerging pathogens
• informing public health responses.

Occupational Therapists contribute indirectly by recognising potential infectious disease concerns, documenting observations accurately and following organisational reporting procedures.

Antimicrobial Resistance

Antimicrobial resistance (AMR) occurs when microorganisms evolve mechanisms that reduce the effectiveness of antimicrobial medicines.

AMR affects:

• bacteria
• viruses
• fungi
• parasites.

Contributing factors include:

• inappropriate antimicrobial prescribing
• incomplete treatment courses
• excessive antimicrobial use in humans
• inappropriate antimicrobial use in animals
• environmental contamination.

Antimicrobial resistance is recognised by the World Health Organization as one of the greatest threats to global health.

Although Occupational Therapists do not prescribe antimicrobials, they contribute by:

• supporting infection prevention
• promoting hand hygiene
• educating clients
• reducing opportunities for infection
• encouraging appropriate referral when infection is suspected.

Lessons from the COVID-19 Pandemic

The COVID-19 pandemic demonstrated both the strengths and vulnerabilities of healthcare systems worldwide.

Important lessons included:

• the value of preparedness
• importance of infection prevention
• significance of clear communication
• role of evidence-informed decision-making
• importance of interdisciplinary collaboration
• need for flexible service delivery
• value of telehealth
• importance of protecting vulnerable populations
• significance of public trust.

Many of these lessons continue to influence occupational therapy practice and infection prevention planning.

The Occupational Therapist’s Role

Occupational Therapists contribute to global health security by:

• remaining informed about emerging infectious diseases
• implementing evidence-based infection prevention practices
• adapting services during outbreaks
• educating clients and carers
• recognising potential infection risks
• supporting public health measures
• collaborating with multidisciplinary teams
• promoting continuity of care.

Occupational Therapists also play an important role in helping clients maintain occupational participation during periods of infectious disease disruption while balancing individual needs with broader public health considerations.

Key Practice Principle

Emerging infectious diseases and global health threats require Occupational Therapists to remain informed, adaptable and collaborative. By understanding the drivers of disease emergence, recognising the interconnected nature of human, animal and environmental health, and applying evidence-based infection prevention practices, Occupational Therapists contribute to global health security, resilient healthcare systems and the safe participation of individuals and communities within a One Health framework.