Environmental Management (0680) | Managing water-related disease

Environmental Management (0680) Study Notes: Managing Water-Related Disease (4.10)

Welcome to Section 4.10: The Hidden Dangers in Water!

Hello! In this chapter, we move from managing water quantity (supply and usage) to managing water quality, specifically how water can spread deadly diseases. This is a critical area of Environmental Management because ensuring safe water is key to human survival and development.

Don't worry if the biology seems a bit complex; we will break down the life cycles and control methods into simple, easy-to-remember steps!

1. Introduction to Water-Related Diseases

What are Water-Related Diseases?

These are illnesses spread because of contaminated water or by organisms (like mosquitoes) that breed in water.
We focus on two major examples as required by the syllabus: Malaria and Cholera.

• Cholera: A bacterial disease spread when people drink water contaminated with human waste (faeces). This is often an issue of poor sanitation and lack of potable water (safe drinking water).
• Malaria: A parasitic disease spread by mosquitoes, which breed in stagnant water. This is an issue of vector control (controlling the carrier organism).

Key Takeaway: Water can be both the source of life and the source of illness if it is not managed correctly.

2. Managing Malaria

What is Malaria?

Malaria is caused by a tiny living organism called a parasite. This parasite is transmitted to humans by the bite of an infected female Anopheles mosquito. The mosquito is called the vector (the carrier) of the disease.

The Life Cycle of the Malaria Parasite

Understanding the life cycle is crucial for knowing where to break the chain of infection.

Step-by-Step Cycle (Simplified)

1. The Vector Bites (Infection Stage): An infected mosquito bites a human. The malaria parasites enter the person's bloodstream.
2. Liver Invasion: The parasites travel to the human's liver cells, where they multiply rapidly (like setting up a base camp).
3. Red Blood Cell Attack: The multiplied parasites burst out of the liver and invade the red blood cells, multiplying again. This is when the person starts feeling symptoms (fever, chills).
4. The Vector Bites (Transmission Stage): A healthy, uninfected mosquito bites the sick person and sucks up the infected blood (including the parasites).
5. Development in the Mosquito: The parasites develop and multiply inside the mosquito's gut and travel to its salivary glands, ready to infect the next human. The cycle continues!

Memory Aid: Think of the cycle as starting and ending with the mosquito bite: Mosquito $\rightarrow$ Liver $\rightarrow$ Blood $\rightarrow$ Mosquito.

Strategies to Control Malaria (Breaking the Cycle)

We control malaria by targeting the parasite, the human host, and the vector.

1. Targeting the Parasite (In the Human)

Strategies focus on treatment or prevention using medicine:

• Antimalarial Drugs: These medicines can be used in two ways:
  • Prevention: Taken before travelling to malaria-prone areas to prevent the parasite from establishing itself in the body.
  • Treatment: Used to kill the parasites in the bloodstream of an infected person.

2. Targeting the Vector (The Mosquito)

This is known as Vector Control and is one of the most effective methods.

• Insecticides/Spraying: Applying chemicals to kill mosquitoes. This includes:
  • Spraying walls inside houses where mosquitoes rest (Indoor Residual Spraying).
  • Spraying mosquito breeding sites (ponds, drainage areas).
• Protective Measures: Preventing bites using physical barriers:
  • Mosquito Nets: Especially those treated with insecticide, used over beds at night.
  • Window/door screens and mosquito repellent.
• Habitat Management: Reducing the places where mosquitoes can breed:
  • Draining stagnant water (e.g., clearing old tyres, open containers, or poorly drained land).
  • Introducing fish into water bodies to eat mosquito larvae.

3. Eradication

Eradication means the complete removal of the disease from an area or the world. While ambitious, this is the long-term goal for many infectious diseases. It requires sustained, coordinated efforts combining all the strategies above.

3. Managing Cholera

What is Cholera?

Cholera is an acute (sudden and severe) diarrhoeal illness caused by the bacterium Vibrio cholerae. It can be fatal within hours if not treated, due to severe dehydration.

Did you know? Cholera is often associated with disasters like floods or earthquakes, because these events destroy clean water and sewage systems, mixing human waste and drinking water.

How is Cholera Spread?

Cholera is spread through the faecal-oral route. This means someone ingests (swallows) food or water contaminated with the faeces (poop) of an infected person.

In many developing areas, untreated sewage contaminates rivers, wells, or reservoirs, which are then used as the primary drinking water source.

Strategies to Control Cholera

Controlling cholera focuses on two main pillars: Sanitation (stopping the source of contamination) and Water Treatment (making the water safe to drink).

1. Safe Drinking Water Supply (Potable Water)

The most effective strategy is providing access to a reliable supply of potable water. Potable water is water that is safe for human consumption.

• Protected Sources: Ensuring wells and boreholes are protected from surface run-off and sewage contamination.
• Infrastructure: Installing and maintaining piped water systems that deliver clean water directly to homes, separating it entirely from sewage lines.

2. Water Treatment Methods

Even if the supply is suspected to be contaminated, treating the water immediately before consumption is vital.

A. Boiling

Boiling water is the simplest and most effective way to kill all disease-causing microorganisms, including the cholera bacteria.

• Method: Bring water to a rolling boil for at least one minute.
• Evaluation: Very reliable, but requires fuel (wood, gas, electricity) and time, which can be difficult or expensive for struggling families.

B. Chlorination

Chlorination is the process of adding chlorine (or chlorine compounds) to water. Chlorine is a powerful disinfectant that kills bacteria and viruses.

• Large Scale: Used in municipal water treatment plants to disinfect huge volumes of water before it enters the distribution network.
• Small Scale: Used in homes or emergency situations using chlorine tablets or drops (like diluted bleach) to treat water stored in buckets or containers.

3. Improved Sanitation (The Prevention Stage)

While the syllabus focuses on water treatment, controlling the spread of cholera relies fundamentally on preventing water contamination in the first place:

• Proper Sewage Treatment: Collecting and treating human sewage (faeces) so it is never released untreated into water sources. (This links back to Section 4.9: Managing pollution of fresh water.)
• Hand Washing: Promoting hygiene practices, especially washing hands after using the toilet and before preparing food.

4. Summary of Water-Related Disease Management

Congratulations! You have covered two major types of water-related diseases. Remember the key distinction between the two diseases when evaluating control strategies in the exam:

Disease	Transmission Method	Primary Control Focus	Specific Strategies
Malaria	Vector (Mosquito bite)	Controlling the mosquito (Vector Control)	Nets, insecticides, draining stagnant water, antimalarial drugs.
Cholera	Faecal-oral (Contaminated water/food)	Securing clean water and sanitation	Safe water supply (potable water), boiling, chlorination, sewage treatment.

Keep up the great work! You've successfully navigated this important environmental health topic.