Human Diseases — Set 7

Correct Answer: B. Typhoid

• **Typhoid** = a bacterial disease caused by *Salmonella typhi*, spread through contaminated water and food; it is the classic water-borne disease asked in every competitive exam. • **Transmission route** — the bacterium enters the body via drinking or eating anything contaminated with infected sewage or faeces. • Symptoms include sustained high fever, weakness, stomach pain, and rose-coloured spots on the chest. • 💡 Option A (Chikungunya) is wrong because it is a vector-borne viral disease spread by the *Aedes* mosquito; Option C (Tuberculosis) is wrong because it is an air-borne bacterial disease spread through respiratory droplets; Option D (Measles) is wrong because it is an air-borne viral disease transmitted by coughing or sneezing.

Correct Answer: A. Beri-beri

• **Beri-beri** = a deficiency disease caused by insufficient Vitamin B1 (Thiamine); it affects the nervous system and heart, with symptoms like muscle weakness, nerve damage, and cardiovascular problems. • **Two forms** — Dry beri-beri affects peripheral nerves causing paralysis; Wet beri-beri affects the heart causing fluid accumulation. • Common among people whose diet relies heavily on polished (milled) white rice, which strips away thiamine. • 💡 Option B (Pellagra) is wrong because it is caused by deficiency of Vitamin B3 (Niacin); Option C (Rickets) is wrong because it is caused by deficiency of Vitamin D leading to weak and deformed bones in children; Option D (Scurvy) is wrong because it is caused by deficiency of Vitamin C causing bleeding gums and skin lesions.

Correct Answer: A. Kwashiorkor

• **Kwashiorkor** = a severe form of protein-energy malnutrition that occurs in young children when calorie intake is adequate but protein intake is very low; it causes a characteristic pot-belly appearance, oedema (swelling), and discoloured hair. • **Key marker** — oedema (fluid retention especially in the belly) distinguishes Kwashiorkor from Marasmus, which is caused by deficiency of both protein AND calories. • Most common in sub-Saharan Africa and areas where weaning foods are low in protein. • 💡 Option B (Night Blindness) is wrong because it is caused by deficiency of Vitamin A; Option C (Anaemia) is wrong because it is mainly caused by deficiency of Iron (or Vitamin B12/folate); Option D (Goitre) is wrong because it is caused by deficiency of Iodine.

Correct Answer: B. Rabies

• **Rabies** = a fatal viral disease caused by the *Lyssavirus*, transmitted through the bite of an infected animal (most commonly a dog); hydrophobia (fear of water) is its hallmark late-stage neurological symptom. • **Why hydrophobia** — the virus damages the brain and causes painful throat spasms when the patient tries to swallow water, so even the sight of water triggers terror. • Once symptoms appear, rabies is nearly 100% fatal; post-exposure prophylaxis (vaccine) must be given immediately after a bite. • 💡 Option A (Tetanus) is wrong because it causes muscle stiffness and lockjaw, not fear of water; Option C (Dengue) is wrong because it is a vector-borne viral disease causing high fever and platelet drop; Option D (Cholera) is wrong because it is a water-borne bacterial disease causing severe watery diarrhoea.

Correct Answer: B. Thyroid

• **Thyroid gland** = a butterfly-shaped endocrine gland located in the front of the neck; its abnormal enlargement is called Goitre, most commonly caused by iodine deficiency. • **Mechanism** — when iodine is insufficient, the thyroid cannot produce enough hormones (T3 and T4), so the pituitary secretes more TSH to stimulate it, causing the gland to swell. • Iodised salt is the main public health intervention used worldwide to prevent iodine deficiency and Goitre. • 💡 Option A (Pancreas) is wrong because it is a digestive and endocrine gland that secretes insulin, and its diseases are diabetes and pancreatitis; Option C (Adrenal) is wrong because adrenal glands sit above the kidneys and produce adrenaline and cortisol; Option D (Pituitary) is wrong because it is the master gland in the brain and does not enlarge in iodine deficiency.

Correct Answer: B. Blood

• **Blood** = Leukaemia is a cancer of the blood and bone marrow, characterised by the uncontrolled production of abnormal white blood cells (WBCs) that crowd out normal blood cells. • **Key impact** — the surplus of non-functional WBCs suppresses the production of red blood cells and platelets, leading to anaemia, frequent infections, and excessive bleeding. • It is also called 'blood cancer'; bone marrow is the primary site where cancerous cells originate before flooding the bloodstream. • 💡 Option A (Liver) is wrong because liver cancer is called Hepatoma or Hepatocellular Carcinoma; Option C (Lungs) is wrong because lung cancer primarily affects lung tissue, not blood cells; Option D (Skin) is wrong because skin cancer (melanoma) affects skin cells, not the haematopoietic system.

Correct Answer: D. Vitamin K

• **Vitamin K** = a fat-soluble vitamin essential for blood clotting (coagulation); it activates clotting factors II, VII, IX, and X produced in the liver, without which blood cannot clot properly. • **Result of deficiency** — prolonged bleeding from even small wounds, easy bruising, and in severe cases, internal haemorrhage; newborns are especially at risk (Haemorrhagic Disease of Newborn). • Vitamin K is found in green leafy vegetables (spinach, kale) and is also synthesised by gut bacteria. • 💡 Option A (Vitamin D) is wrong because its deficiency causes Rickets in children and Osteomalacia in adults (weak bones), not bleeding; Option B (Vitamin A) is wrong because its deficiency causes Night Blindness and increased infection risk; Option C (Vitamin C) is wrong because its deficiency causes Scurvy with bleeding gums, but the direct anticoagulation mechanism is specific to Vitamin K.

Correct Answer: C. Bacteria

• **Bacteria** = Tuberculosis (TB) is caused by *Mycobacterium tuberculosis*, a slow-growing, rod-shaped bacterium that primarily infects the lungs (Pulmonary TB) but can spread to other organs. • **Transmission** — it spreads through the air when an infected person coughs, sneezes, or speaks; the bacteria remain suspended in tiny droplets called droplet nuclei. • BCG (Bacillus Calmette-Guérin) vaccine provides protection against severe TB in children; treatment requires a course of multiple antibiotics for 6 months or more. • 💡 Option A (Amoeba) is wrong because Amoeba causes Amoebic Dysentery, a parasitic gut infection; Option B (Virus) is wrong because TB is not viral — viruses cause diseases like HIV, Influenza, and Measles; Option D (Fungus) is wrong because fungal infections of the lung (e.g., Aspergillosis) are distinct from TB and far less common.

Correct Answer: B. Anaemia

• **Anaemia** = a condition in which the blood has a lower than normal number of red blood cells or haemoglobin; Iron deficiency anaemia is the most common type, as iron is a core component of haemoglobin, the oxygen-carrying protein in RBCs. • **Symptoms** — fatigue, pale skin, shortness of breath, rapid heartbeat, and dizziness due to reduced oxygen delivery to body tissues. • Iron-rich foods include red meat, spinach, lentils, and fortified cereals; Vitamin C helps in iron absorption. • 💡 Option A (Marasmus) is wrong because it is caused by severe deficiency of both protein and calories, causing extreme wasting in children; Option C (Scurvy) is wrong because it is caused by Vitamin C deficiency; Option D (Rickets) is wrong because it is caused by Vitamin D deficiency leading to soft and deformed bones.

Correct Answer: C. Malaria

• **Malaria** = a life-threatening parasitic disease caused by *Plasmodium* species (mainly *P. falciparum*, *P. vivax*, *P. malariae*, *P. ovale*), transmitted to humans through the bite of an infected female *Anopheles* mosquito. • **Lifecycle key fact** — the parasite first multiplies in the liver and then invades red blood cells, causing periodic cycles of fever, chills, and sweating as RBCs rupture. • *P. falciparum* is the most dangerous species and is responsible for cerebral malaria; DDT spraying and mosquito nets are classic preventive measures. • 💡 Option A (Cholera) is wrong because it is a water-borne bacterial disease caused by *Vibrio cholerae*; Option B (Dengue) is wrong because it is a viral disease spread by the *Aedes aegypti* mosquito, not a Plasmodium parasite; Option D (Typhoid) is wrong because it is caused by the bacterium *Salmonella typhi* via contaminated water.