Disease Emergence and Flood Impact: Global Challenges

Global Health Challenges

Emerging and Re-emerging Infectious Diseases

According to the WHO (World Health Organization), from the onset of AIDS to SARS (Severe Acute Respiratory Syndrome), the rate of new infectious diseases has been approximately one per year. These emerging diseases are often transmitted by unknown pathogens. Some of these germs have long been confined to their natural habitats before coming into contact with humans. This is believed to have occurred with devastating hemorrhagic fevers such as Ebola.

Other cases involve re-emerging diseases, where major infectious diseases of the past, dangerous to the human species, have resurfaced due to mutations. Some of these recrudescent diseases are now affecting regions of the world where they were once thought to be eradicated.

Understanding Disease Causation: Koch's Postulates

To establish a causal relationship between a microorganism and a disease, the following postulates are traditionally applied:

1. The microorganism must be present in all individuals suffering from the disease.
2. The organism must be recovered from the diseased individual and isolated in a pure culture.
3. The cultured organism must cause the same disease when inoculated into a healthy, susceptible host.
4. The microorganism must be re-isolated from the experimentally infected host.

Natural Risks and Environmental Impact

Flooding: A Major Natural Hazard

A flood is the inundation of areas that are typically dry. It constitutes the most significant natural risk in Spain, both in terms of fatalities and material damage. In most frequent cases, the natural process causing floods is torrential rainfall. This supplies a watershed with an abnormally large volume of water, leading to swollen rivers or flash floods.

In Spain, particularly in the Mediterranean region, drought periods are often abruptly ended by torrential rains, leading to a high risk of flooding. However, most damage results from the occupation of floodplains by people or their property. The occupation of flood areas along canals or riverbeds, which are naturally prone to seasonal flooding, exacerbates this risk.

Human Factors Exacerbating Flood Risk

Several human activities contribute to increased flood vulnerability:

• Deforestation and Loss of Vegetative Cover: This reduces soil infiltration and, consequently, increases surface runoff and the likelihood of flooding.
• Impermeable Surfaces and Land Use Changes: Covering soil with impermeable materials, such as in housing estates and car parks, impedes natural water infiltration.
• Infrastructure Interference: Works like roads or railway routes can create a barrier effect, hindering the natural flow of water and exacerbating flood conditions.