Health, disease and the development of medicines Study Guide

A pathogen is an organism that can cause disease in another organism, its host. These disease-causing agents come in various forms, including viruses, bacteria, fungi, and protists, each with distinct characteristics and mechanisms of causing harm. Viruses are non-living particles that replicate inside host cells, often damaging or destroying them. Bacteria are single-celled prokaryotic organisms that can cause disease by producing toxins or directly invading tissues. Fungi, which can be single-celled (like yeast) or multicellular (like moulds), cause disease by invading tissues or releasing spores. Protists are a diverse group of mostly single-celled eukaryotic organisms, some of which are parasitic and cause diseases like malaria. Understanding the nature of different pathogens is crucial for preventing and treating infectious diseases.

Sexually Transmitted Infections (STIs) are a range of infections spread primarily through sexual contact. These infections can be caused by bacteria, viruses, or other microorganisms. Two significant examples are Chlamydia, caused by bacteria, and Human Immunodeficiency Virus (HIV), caused by a virus. Chlamydia often presents without obvious symptoms in its early stages, leading to it being undiagnosed and contributing to its spread. Untreated Chlamydia can lead to serious reproductive health issues. HIV attacks the immune system, making the body vulnerable to other infections and certain cancers. The primary mode of transmission for both STIs is through unprotected sexual activity, where bodily fluids containing the pathogens are exchanged. This includes vaginal, anal, and oral sex. Additionally, HIV can be transmitted through sharing needles, from mother to child during pregnancy, childbirth, or breastfeeding. Reducing and preventing the spread of STIs involves multiple strategies including consistent and correct use of barrier methods like condoms, regular testing, particularly with new partners or if symptoms arise, and limiting the number of sexual partners. Education on safe sexual practices and access to treatment for diagnosed infections are also crucial in managing and reducing STI prevalence.