C8

Climate Change and Vulnerable Populations

Impact of Climate Change on Food systems:
- Climate change significantly alters the quality and distribution of food.
- It impacts food safety and nutrition through shifts in agricultural productivity and the environmental conditions required for food storage and distribution.
Vulnerability of Specific Demographics:
- Children and Pregnant Women: These groups are more vulnerable to the impacts of climate change due to physiological differences and higher nutritional requirements.
Environmental Impact of Fossil Fuels:
- The burning of fossil fuels affects climatic patterns globally by increasing the concentration of greenhouse gases in the atmosphere, leading to shifts in long-term weather and temperature patterns.

Global Burden and Statistical Key Facts of Vector-Borne Diseases

Vector-borne diseases account for more than $17\%$ of all infectious diseases worldwide.
These diseases cause more than $700,000$ deaths annually.
Pathogenic causes of vector-borne diseases include parasites, bacteria, and viruses.
Malaria Statistics:
- Malaria is a parasitic infection transmitted specifically by Anopheles mosquitoes.
- There are an estimated $219$ million global cases of malaria annually.
- The disease results in more than $400,000$ deaths every year, with the majority of fatalities occurring in children under the age of $5$ years.
Dengue Statistics:
- Dengue is the most prevalent viral infection transmitted by Aedes mosquitoes.
- More than $3.9$ billion people across over $129$ countries are at risk of contracting dengue.
- Annual estimates suggest there are $96$ million symptomatic cases and approximately $40,000$ deaths.
Other Significant Vector-Borne Pathogens:
- Viral diseases transmitted by mosquitoes: Chikungunya fever, Zika virus fever, yellow fever, West Nile fever, and Japanese encephalitis.
- Viral diseases transmitted by ticks: Tick-borne encephalitis.
- Diseases affecting hundreds of millions globally: Chagas disease (triatomine bugs), leishmaniasis (sandflies), and schistosomiasis (snails).

Definitions and Mechanisms of Transmission

Vectors:
- Vectors are living organisms capable of transmitting infectious pathogens between humans, or from animals to humans.
- A majority of vectors are bloodsucking insects.
- Transmission Mechanism: These insects ingest disease-producing microorganisms during a blood meal from an infected host (human or animal). The pathogen then replicates within the vector. Once the vector becomes infectious, it can transmit the pathogen to a new host during subsequent bites for the remainder of its life.
Vector-borne Diseases:
- These are human illnesses caused by parasites, viruses, and bacteria specifically transmitted by biological vectors.
- Impacted populations: The burden is highest in tropical and subtropical areas, disproportionately affecting the poorest populations in the world.
- Major outbreaks since $2014$ : Significant outbreaks of dengue, malaria, chikungunya, yellow fever, and Zika have overwhelmed health systems and caused high mortality rates.
- Chronic conditions: Diseases such as Chikungunya, leishmaniasis, and lymphatic filariasis result in chronic suffering, life-long morbidity, disability, and occasional social stigmatization.

Classification of Vector-Borne Diseases by Vector and Pathogen

Mosquito: Aedes
- Chikungunya: Caused by a Virus.
- Dengue: Caused by a Virus.
- Lymphatic filariasis: Caused by a Parasite.
- Rift Valley fever: Caused by a Virus.
- Yellow Fever: Caused by a Virus.
- Zika: Caused by a Virus.
Mosquito: Anopheles
- Lymphatic filariasis: Caused by a Parasite.
- Malaria: Caused by a Parasite.
Mosquito: Culex
- Japanese encephalitis: Caused by a Virus.
- Lymphatic filariasis: Caused by a Parasite.
- West Nile fever: Caused by a Virus.
Aquatic Snails
- Schistosomiasis (bilharziasis): Caused by a Parasite.
Blackflies
- Onchocerciasis (river blindness): Caused by a Parasite.
Fleas
- Plague: Caused by Bacteria; transmitted from rats to humans.
- Tungiasis: Caused by an Ectoparasite.
Lice
- Typhus: Caused by Bacteria.
- Louse-borne relapsing fever: Caused by Bacteria.
Sandflies
- Leishmaniasis: Caused by Bacteria.
- Sandfly fever (phlebotomus fever): Caused by a Virus.
Ticks
- Crimean-Congo haemorrhagic fever: Caused by a Virus.
- Lyme disease: Caused by Bacteria.
- Relapsing fever (borreliosis): Caused by Bacteria.
- Rickettsial diseases (e.g., spotted fever and Q fever): Caused by Bacteria.
- Tick-borne encephalitis: Caused by a Virus.
- Tularaemia: Caused by Bacteria.
Triatomine Bugs
- Chagas disease (American trypanosomiasis): Caused by a Parasite.
Tsetse Flies
- Sleeping sickness (African trypanosomiasis): Caused by a Parasite.

Global Health Response and Prevention Strategies

World Health Organization (WHO) Response Framework:
- Guidance: Providing evidence-based guidance for vector control and personal protection against infection.
- Technical Support: Assisting countries in the effective management of cases and disease outbreaks.
- Burden Capture: Supporting nations in improving reporting systems to accurately reflect the true burden of disease.
- Capacity Building: Providing training on clinical management, diagnosis, and vector control through collaborating centers.
- Innovation: Supporting the development and evaluation of new tools, technologies, and approaches for disease management and vector control.
Behavioral and Community Interventions:
- Behavioral change is recognized as a crucial element in reducing the disease burden.
- WHO works with partners to improve public awareness so individuals know how to protect themselves from mosquitoes, ticks, bugs, and flies.
Environmental and Infrastructure Factors:
- Access to safe water and adequate sanitation is critical for the elimination and control of vector-borne diseases.
- Collaborative efforts across government sectors aim to improve water storage and sanitation infrastructure to control diseases at the community level.