Fighting Disease

This section explains how disease can be fought by passive and active immunity, including immunisation, vaccinations and antibiotics. Immunisation is the process by which the body is protected from disease by stimulating the immune system to recognise and fight specific pathogens. Immunisation can occur through active or passive immunity.

Active Immunity

Active immunity occurs when the body’s immune system produces its own antibodies after being exposed to a pathogen or a part of it (such as a virus or bacterium). This type of immunity is long-lasting and can provide lifetime protection.

How it works: The immune system is exposed to a pathogen either through natural infection or vaccination. After exposure, the body produces antibodies to fight the pathogen. Additionally, memory cells are created, which remember how to produce the antibodies quickly if the pathogen is encountered again.

Vaccination: Vaccines contain harmless forms of the pathogen (e.g., dead or weakened pathogens or parts of the pathogen like proteins). Vaccines stimulate the immune system to produce an immune response, including the production of memory cells. As a result, if the body is exposed to the real pathogen in the future, it can mount a faster and stronger response.

• Example: The MMR vaccine (measles, mumps, and rubella) introduces weakened versions of the viruses into the body, allowing the immune system to develop immunity without causing illness.

Passive Immunity

Passive immunity is when an individual receives antibodies produced by another organism, rather than producing them themselves. This type of immunity provides immediate protection, but it is temporary, as the body does not produce memory cells.

How it works: Antibodies are transferred to an individual either naturally (e.g., through breast milk) or artificially (e.g., via an injection of antibodies).

Example: Newborn babies receive passive immunity from their mothers through the placenta and breast milk, which provides short-term protection against infections.

• Example of artificial passive immunity: Immunoglobulin injections, which provide immediate protection against diseases like rabies or hepatitis B.

Antibiotics and Painkillers

Antibiotics

Antibiotics are drugs used to treat infections caused by bacteria. They work by either killing bacteria or preventing their growth and reproduction. Antibiotics are specific to bacterial infections and do not work against viruses.

How they work: Antibiotics target specific features of bacterial cells, such as the cell wall or the machinery used for replication, which human cells do not have. This makes antibiotics effective against bacteria without harming human cells.

• Example: Penicillin is an antibiotic that interferes with the formation of bacterial cell walls, causing the bacteria to burst.

Important considerations: Antibiotics should only be prescribed for bacterial infections, as they are ineffective against viral infections (e.g., the common cold or flu). Misuse of antibiotics can lead to resistance, so they should always be taken as prescribed by a doctor.

Painkillers

Painkillers (analgesics) are drugs used to relieve pain. Unlike antibiotics, painkillers do not treat the underlying cause of pain but instead reduce the sensation of pain.

How they work: Painkillers work by blocking the signals that send pain sensations to the brain or by reducing inflammation (which can cause pain).

• Example: Paracetamol is a common painkiller that reduces pain and lowers fever, but it does not affect the infection causing the pain.
• Example: Ibuprofen is an anti-inflammatory painkiller that reduces swelling and pain.

Painkillers are commonly used for mild to moderate pain, but they do not cure infections or treat the underlying cause of pain.

Antibiotic Resistance

Antibiotic resistance occurs when bacteria evolve to become resistant to the effects of an antibiotic. This means that antibiotics that once worked to treat certain bacterial infections are no longer effective against those bacteria.

How Antibiotic Resistance Develops

Bacteria can evolve resistance through mutations in their genetic material. If a bacterium is exposed to an antibiotic, some bacteria may have a mutation that makes them resistant to the drug. These resistant bacteria can survive and reproduce, passing on the resistance to their offspring. Over time, the population of resistant bacteria grows, and the antibiotic becomes less effective.

Factors contributing to antibiotic resistance: 

• Overuse of antibiotics: Using antibiotics when they are not needed (e.g., for viral infections like the flu).
• Incomplete courses of antibiotics: Not finishing the full course of antibiotics can leave surviving bacteria that are not fully killed, allowing them to develop resistance.
• Misuse in agriculture: Overuse of antibiotics in farming can contribute to the spread of resistant bacteria.

Consequences of Antibiotic Resistance

Antibiotic resistance makes it more difficult to treat bacterial infections, leading to longer hospital stays, higher medical costs, and increased mortality rates. Infections that were once easily treated may become life-threatening due to the lack of effective antibiotics.

• Example: Antibiotic-resistant strains of bacteria like MRSA (Methicillin-resistant Staphylococcus aureus) are becoming more common and harder to treat.

Preventing Antibiotic Resistance

To prevent antibiotic resistance, it is important to:

• Only use antibiotics when prescribed by a doctor.
• Complete the full course of antibiotics, even if you feel better before finishing the medication.
• Reduce the use of antibiotics in agriculture.
• Practice good hygiene to prevent infections from spreading.

Summary

• Immunisation involves active immunity, where the immune system produces its own antibodies, and passive immunity, where antibodies are transferred from another source.
• Antibiotics are used to treat bacterial infections, while painkillers alleviate pain but do not treat the cause.
• Antibiotic resistance is a growing problem caused by the overuse and misuse of antibiotics, making it crucial to follow medical guidelines and use antibiotics responsibly to maintain their effectiveness in treating bacterial infections.

By understanding how immunisation, antibiotics, and painkillers work, we can better protect ourselves from diseases and use medicines in a responsible way.