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1. Air pollution and climate change -

The WHO identifies climate change as the defining health threat of the 21st century. Rising global temperatures cause more intense natural disasters, spread diseases more quickly, and increase food and water insecurity.

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1. Air pollution and climate change -

Floods, hurricanes, and droughts displace millions, disrupt healthcare access, and contaminate essential resources. These environmental upheavals foster disease outbreaks, mental health crises, and long-term disrepair in public health infrastructure, especially in low-income and climate-fragile regions.

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1. Air pollution and climate change -

As climate conditions deteriorate, people are forced to migrate, often without reliable access to care. These mass movements pressure the healthcare services of host nations, and can even introduce unfamiliar diseases to new regions.

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2. Noncommunicable diseases -

Over 70% of global deaths now stem from noncommunicable diseases like heart disease, diabetes, and cancer. The WHO flags them as a growing threat fueled by sedentary lifestyles, dietary shifts, and increased tobacco and alcohol consumption, particularly in urbanized societies.

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2. Noncommunicable diseases -

Highly processed foods, pollution, stress, and limited space for physical activity contribute to the spread of lifestyle-related diseases. These urban risk factors make it difficult for people to adopt healthier habits, particularly in lower-income neighborhoods with limited resources.

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2. Noncommunicable diseases -

Despite clear data linking behavior to disease outcomes, many nations underfund prevention efforts. Education, screening, and early intervention programs are cost-effective yet often overlooked, allowing manageable conditions to escalate into life-threatening crises with enormous costs to society.

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3. Global influenza pandemic -

A new influenza pandemic is not a question of "if," but "when." The WHO warns that high mutation rates and widespread animal-human interactions create the perfect conditions for a novel strain to emerge and spread rapidly across the globe.

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3. Global influenza pandemic -

Global health infrastructure remains uneven. While some countries boast early-warning labs and stockpiles, others lack the tools needed to detect and contain such issues. This leaves large populations exposed and impairs coordinated global responses to rapidly emerging viral threats.

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3. Global influenza pandemic -

Even if a pandemic strain is identified, current vaccine production capabilities may be too slow to curb a first wave. Manufacturing, distribution logistics, and affordability pose challenges, especially in lower-income nations reliant on international assistance during global health emergencies.

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4. Antimicrobial resistance -

The overuse and misuse of antibiotics in humans and animals has accelerated the rise of drug-resistant microbes. The WHO warns that these “superbugs” could turn once-treatable infections into life-threatening conditions.

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4. Antimicrobial resistance -

Surgeries, organ transplants, and even simple injuries could become life-threatening if infections can no longer be treated. The growing inefficacy of antibiotics also threatens immunocompromised patients who rely on such medications as critical lifelines during complex treatments.

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4. Antimicrobial resistance -

Widespread use of antibiotics in livestock and aquaculture further fuels resistance, and enables resistant strains to enter the human food chain. Without strict regulations and oversight, antimicrobial resistance will continue evolving in unexpected ways and on multiple fronts.

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5. Vaccine hesitancy -

Vaccine refusal, even in the face of overwhelming scientific evidence, has allowed preventable diseases to return. The WHO lists vaccine hesitancy among top threats, with cultural distrust, misinformation, and complacency seen as barriers to maintaining public immunity.

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5. Vaccine hesitancy -

Social media platforms have become echo chambers for pseudoscience and conspiracy theories. False claims about vaccine safety and effectiveness erode trust and provide fertile ground for the resurgence of diseases once believed to be nearly eradicated.

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5. Vaccine hesitancy -

Successful vaccination programs depend on relationships built within communities. Engaging local leaders and improving health literacy from a young age are essential steps in restoring trust and addressing doubts among skeptical or underserved populations.

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6. Fragile and vulnerable settings -

Conflict zones, refugee camps, and disaster-hit areas lack stable healthcare infrastructure, which leaves populations vulnerable to disease, malnutrition, and injury. The WHO emphasizes that humanitarian crises must be met with swift, coordinated healthcare responses tailored to chaotic environments.

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6. Fragile and vulnerable settings -

Violence disrupts healthcare delivery, destroys facilities, and endangers workers. In these settings, vaccinations stall, sanitation deteriorates, and outbreaks thrive. This turns once-contained diseases like cholera or measles into rampant killers.

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6. Fragile and vulnerable settings -

Many vulnerable settings are located in border regions where displaced populations cross into neighboring countries. The WHO stresses that cross-border cooperation and shared health protocols are critical to contain infectious outbreaks and provide consistent care for mobile populations.

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7. Dengue -

Dengue, once restricted to specific tropical zones, now threatens half the global population. Fueled by climate change, rapid urbanization, and poor waste management, mosquito breeding grounds are flourishing in areas unprepared for the virus' explosive spread.

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7. Dengue -

Dengue-carrying mosquitoes like Aedes aegypti have adapted to urban environments and can breed in small amounts of stagnant water, which makes traditional eradication techniques less effective. Public health systems must innovate faster to keep up.

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7. Dengue -

Dengue affects productivity, tourism, and household income. In hard-hit areas, outbreaks overwhelm hospitals and devastate families, forcing children out of school and adults out of work. Recovery takes time, and repeat infections can increase risk of severe illness or death.

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8. HIV -

Though treatment access has improved globally, new HIV infections remain stubbornly high in many regions. The WHO cautions that the fight is far from over, especially where healthcare access and education are limited or where stigma prevents open dialogue.

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8. HIV -

Younger generations (particularly in high-burden regions) are often not receiving adequate sex education or awareness campaigns. Without accurate knowledge of transmission risks and protection strategies, HIV continues spreading among young people at alarming rates.

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8. HIV -

Access to antiretrovirals and HIV testing remains uneven. In many low-income countries, geographic isolation, cost barriers, and healthcare staffing shortages mean that millions go undiagnosed or untreated, despite international pledges to end the HIV epidemic by 2030.

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9. Weak primary healthcare -

A robust primary healthcare system acts as the foundation of any health response, but many countries lack it. The WHO highlights that, without first-contact care providers, early diagnoses and disease management are lost, which results in overwhelmed hospitals and sicker populations.

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9. Weak primary healthcare -

From managing hypertension to providing maternal care, primary health services are essential. When they’re absent, preventable conditions worsen until they require expensive, high-level interventions. This leads to unsustainable burdens on national health budgets and human lives alike.

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9. Weak primary healthcare -

Understaffed and underfunded primary care facilities leave health workers overstretched. With few resources, low pay, and high emotional stress, many workers exit the profession, which causes even worse shortages and leaves entire communities without access to consistent medical guidance.

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10. High-threat pathogens -

Ebola, Marburg, and other viral hemorrhagic fevers continue to emerge in fragile health zones. These pathogens (with high mortality rates and complex containment needs) are prioritized by the WHO as key threats requiring specialized response strategies and investment.

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10. High-threat pathogens -

When high-threat pathogens emerge, delays in response can cost thousands of lives. Whether due to political instability, public mistrust, or even logistical barriers, any delay in contact tracing or quarantining significantly amplifies the danger to both local and global populations.

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10. High-threat pathogens -

In previous Ebola outbreaks, fear and misunderstanding led to violence against healthcare workers. The WHO emphasizes that effective containment must include cultural training, community engagement, and respectful handling of local customs to ensure cooperation and trust during outbreak responses.

Sources: (World Health Organization) (Britannica)

See also: Times the WHO declared a public health emergency

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