Infectious diseases remain one of the major challenges to global health. They can affect almost every organ system and are caused by bacteria, viruses, fungi, or parasites. This unit focuses on central nervous system infections, systemic bacterial diseases, urinary tract infections, and sexually transmitted diseases (STDs).
Infectious Diseases
Infectious diseases are caused by pathogenic microorganisms, such as bacteria, viruses, fungi, or parasites.
- Meningitis: An inflammation of the meninges, the protective membranes that surround the brain and spinal cord. It can be caused by bacterial, viral, or fungal infections. Symptoms include a severe headache, fever, and a stiff neck.
- Typhoid: A bacterial infection caused by Salmonella Typhi. It is transmitted through contaminated food and water and is common in areas with poor sanitation. Symptoms include a high fever, headache, abdominal pain, and a rash.
- Leprosy: A chronic infectious disease caused by the bacterium Mycobacterium leprae. It primarily affects the skin, peripheral nerves, upper respiratory tract, eyes, and testes. It is characterized by skin lesions and nerve damage. While it is infectious, it is not highly contagious and is curable with multidrug therapy.
- Tuberculosis (TB): A bacterial infection caused by Mycobacterium tuberculosis that primarily affects the lungs. It spreads through airborne droplets when an infected person coughs or sneezes. Symptoms include a chronic cough, fever, night sweats, and weight loss.
- Urinary Tract Infections (UTIs): Bacterial infections that affect any part of the urinary system, including the kidneys, bladder, ureters, or urethra. They are more common in women due to anatomical differences. Symptoms include a painful, burning sensation during urination, a frequent urge to urinate, and cloudy or bloody urine.
Sexually Transmitted Diseases (STDs)
Sexually transmitted diseases are infections passed from person to person through sexual contact.
- AIDS (Acquired Immunodeficiency Syndrome): A chronic, life-threatening condition caused by the Human Immunodeficiency Virus (HIV). HIV attacks the body’s immune system, specifically CD4 T cells, making the body vulnerable to opportunistic infections and certain cancers. AIDS is the final, most severe stage of HIV infection.
- Syphilis: A bacterial infection caused by Treponema pallidum. It progresses through several stages:
- Primary Stage: Characterized by a painless sore (chancre) at the site of infection.
- Secondary Stage: Involves a non-itchy body rash, fever, and swollen lymph nodes.
- Latent Stage: A period with no symptoms.
- Tertiary Stage: Can occur years later and cause severe damage to the heart, brain, and other organs.
- Gonorrhea: A bacterial infection caused by Neisseria gonorrhoeae. It can infect the genital tract, rectum, and throat. In men, it can cause pain during urination and a pus-like discharge from the penis. In women, symptoms are often mild or absent but can include painful urination and vaginal discharge. If left untreated, it can lead to infertility.