The mechanisms of infection

Infection is a complex process that involves the invasion of pathogenic organisms into the human body. Understanding the mechanisms behind infections is crucial for developing treatments and preventing diseases.

What is an Infection?

An infection occurs when microorganisms such as bacteria, viruses, fungi or parasites invade the body and begin to multiply. Not all infections cause disease; The human body is home to trillions of microorganisms, many of which are beneficial. However, when harmful pathogens overcome the body’s defenses, they can cause disease.

Infection Mechanisms

Entrance to the Body

Pathogens can enter the body through various routes:

1. Direct contact: Infections can spread through direct contact with an infected person, such as through kissing, sexual intercourse, or contact with open wounds.
2. Aerosols and Drops: Respiratory viruses, such as SARS-CoV-2, are transmitted through small droplets expelled when an infected person coughs, sneezes or talks.
3. Ingestion: Contaminated food or water can introduce bacteria such as Salmonella or E. coli into the digestive system.
4. Vectors: Insects such as mosquitoes and ticks can transmit pathogens directly through bites.
5. Contaminated Surfaces: Contaminated objects can transfer pathogens when we touch a surface and then put our hands to our mouth, nose, or eyes.

Multiplication and Dissemination

Once inside the body, pathogens must find an environment conducive to multiplying. This process varies depending on the type of pathogen:

1. Virus: Viruses invade the host’s cells and use the cellular machinery to replicate their genetic material. This can lead to the destruction of infected cells and the release of new viral particles.
2. bacteria: Bacteria reproduce through binary fission, a process in which one bacterial cell divides into two. Some bacteria can release toxins that damage host tissues and help spread the infection.
3. Fungi and Parasites: These organisms can multiply both inside and outside the host’s cells, depending on their life cycle and environmental conditions.

Immune System Evasion

To establish an infection, pathogens must evade the host’s immune system. Some evasion mechanisms include:

1. Antigenic Variation: Some pathogens can change the proteins on their surface to avoid being recognized by the immune system.
2. Inhibition of the Immune Response: Viruses like HIV can attack and destroy immune system cells, weakening the body’s ability to fight infection.
3. Biofilm Formation: Some bacteria can form biofilms, structures that protect them from the action of antibiotics and the immune response.

Immune response

The human immune system has several lines of defense to fight infections:

1. Physical and Chemical Barriers: The skin, mucous membranes and secretions such as saliva and gastric acid act as first lines of defense.
2. Innate Immune Response: Cells of the innate immune system, such as macrophages and neutrophils, attack invading pathogens non-specifically.
3. Adaptive Immune Response: The T and B cells of the adaptive immune system recognize and remember specific pathogens, allowing a faster and more effective response in case of reinfection.

Prevention and Treatment

Infection prevention involves measures such as vaccination, proper hygiene, and the use of antimicrobials. Treatments vary depending on the type of pathogen:

1. Antibiotics: Used to treat bacterial infections, although excessive use can lead to antibiotic resistance.
2. Antivirals: Medications that inhibit viral replication.
3. Antifungal and Antiparasitic: Used to treat infections caused by fungi and parasites, respectively.