Environmental factors affecting disease incidence

Environmental conditions play a significant role in the spread and incidence of diseases across different regions.

Climatic influences on disease spread

• Precipitation patterns:
  • High rainfall supports the survival and growth of disease vectors like insects, increasing the prevalence of infectious diseases in wetter climates.
  • Parasitic infections, often spread by insects, are particularly common in areas with heavy seasonal rains.
• Temperature thresholds:
  • Many disease vectors, such as certain mosquito species that transmit viral infections, thrive only in regions where winter temperatures remain above 10°C.
  • Tropical climates, with consistently high temperatures, see more infectious diseases.
  • Additionally, warmer conditions heighten the risk of foodborne illnesses due to challenges in food storage and increase pollen levels, triggering allergic reactions.
• Extreme weather events:
  • Intense rainfall can lead to flooding, causing sewage overflows and contaminating water supplies, which raises the risk of waterborne diseases.
  • Conversely, drought conditions concentrate disease vectors around scarce water sources, amplifying transmission risks.
• Seasonality and daylight:
  • In polar regions, limited winter daylight contributes to higher rates of seasonal affective disorder (SAD) in Arctic countries compared to other areas.
• Sunlight exposure:
  • Insufficient sunlight can cause vitamin D deficiency, leading to health issues like bone loss, kidney problems, and intestinal disorders.
  • On the other hand, excessive exposure increases the risk of skin cancer due to harmful ultraviolet rays.

Topographical factors influencing disease risk

• Drainage and flooding - River flood plains, often densely populated, are prone to flooding, which contaminates drinking water and spreads gastrointestinal infections. Flooding also displaces populations, creating pressure on resources in new areas.
• Relief and water pooling - Low-lying topographical depressions allow standing water to accumulate, providing breeding grounds for insects. Poorly drained areas also see concentration of animal waste, further contaminating water sources.
• Altitude and UV exposure - Higher elevations expose individuals to greater ultraviolet radiation, increasing the risk of skin cancer due to thinner atmospheric protection.

Health effects of poor air quality

Air quality has a profound impact on human health, particularly in urban and industrialised areas where pollution levels are often elevated.

Sources and impacts of air pollution

• Burning fossil fuels - This releases toxic gases like sulphur dioxide and nitrogen oxides, as well as particulate matter. Prolonged exposure is linked to respiratory issues, cardiovascular diseases, and various forms of cancer.
• Urban air pollution - Poor air quality in cities is responsible for around 1.2 million deaths each year, driven by vehicle emissions, industrial activities, and other pollutants.
• Indoor air quality challenges - Inadequate ventilation, combined with sources like tobacco smoke, mould, pollen, and combustion appliances such as wood stoves or kerosene heaters, leads to respiratory diseases, cardiovascular conditions, and cancers.

Impact of water quality on disease prevalence

Water quality is a critical determinant of public health, with contamination posing significant risks, especially in regions lacking proper sanitation infrastructure.

Sources of water contamination and associated diseases

• Pathogenic contamination - Fecally contaminated water carries pathogens that spread diseases through drinking, bathing, or entry via wounds, eyes, or nasal passages. This results in approximately 3.4 million deaths yearly from waterborne illnesses.
• Specific waterborne diseases:
  • Hepatitis A - A liver infection causing fever and nausea, often transmitted through contaminated water.
  • Cholera - A bacterial infection leading to severe diarrhoea and dehydration, commonly spread via polluted water sources.
• Chemical pollutants - Industrial heavy metals and agricultural pesticide runoff contaminate water supplies, leading to long-term health issues such as cancers and neurological damage.

Role of international organisations in fighting disease

International organisations are pivotal in addressing global health challenges by coordinating efforts to prevent disease spread, fund research, and support healthcare systems.

Key players and their contributions

• Purpose of international bodies - These organisations work to curb the cross-border spread of infectious diseases and facilitate collaborative research on non-communicable conditions.
• United Nations (UN) agencies:
  • World Health Organization (WHO) - Advises governments on health policies, coordinates outbreak control with partners, supports research and training, conducts global health surveillance, and has notable successes like the smallpox eradication campaign (1966-1980) and the Ebola response in West Africa through treatment centres, vaccine development, and transmission prevention strategies.
  • World Bank - Provides funding for healthcare initiatives in developing nations to improve infrastructure and access.
  • UNICEF - Focuses on maternal and child nutrition, access to clean water, and immunisation programmes to protect vulnerable populations.

Contributions and limitations of non-governmental organisations in healthcare

Non-governmental organisations (NGOs) play a vital role in global health by providing direct services and advocating for improved healthcare, especially in underserved areas.

NGO efforts in healthcare provision

• Definition and scope - NGOs are independent, not-for-profit entities functioning as humanitarian charities to address health needs worldwide.
• Key contributions:
  • Global health research - NGOs advance studies to improve medical knowledge and practices.
  • Healthcare delivery - They provide services in developing regions, often reaching remote communities with limited infrastructure.
  • Community-based approaches - NGOs tailor solutions to local needs by engaging directly with affected populations.
• Example - Cancer research organisations fund scientific studies, support patients, provide educational resources to professionals, and push for policy changes to enhance cancer care.

Challenges faced by NGOs

• Operational scale - Compared to international bodies, NGOs operate on a smaller scale, limiting their reach and impact.
• Funding dependency - Reliance on donations and external funding can hinder consistent service delivery and long-term planning.