Ch 10: Human Disease | Exam Fusion Prep

📋 Types of Diseases

Congenital

Present at birth; arising from genetic or prenatal developmental factors
e.g. Cerebral palsy, Haemophilia, Colour blindness

Acquired

Acute: Short-term (Cold, Cholera)
Chronic: Long-lasting (TB, Elephantiasis, Arthritis)

Infectious

Transmitted from sick person via contact/carrier/medium
Caused by pathogens: Virus, Bacteria, Protozoa, Fungi, Worms

🔀 Disease Transmission Routes

Free droplets in air (coughing/sneezing)
Contaminated food and water
Contaminated blood or body fluids
Disease vectors: Flies, Mosquitoes
Indirect contact: Contaminated objects

5F Rule:Flies · Fingers · Fomites · Food · Fluid

⚠️ Non-Infectious Diseases

Type	Examples
Allergies	Hay-fever, Asthma
Nutritional Deficiency	Marasmus (protein–energy / calorie malnutrition), Goitre (iodine), Pellagra (B3), Dental cavities (fluoride)
Degenerative Diseases	Heart attack, Arthritis, Diabetes, Glaucoma, Cataract
Mental-health / Eating Disorders	Depression, Anorexia nervosa; epilepsy is a neurological seizure disorder
Pollution Related	Arsenic (As) → Black foot disease \| Cadmium (Cd) → Itai-itai \| Fluoride water → Knock-Knee syndrome
Cancer	Uncontrolled cell growth — Blood cancer (Leukemia), Carcinoma, Sarcoma

⚠ Exam Trap

Arsenic → Black foot | Cadmium → Itai-itai | Fluoride → Knock-Knee syndrome. These are three different pollutants associated with three different diseases and should not be confused.

🦠 Viral Diseases — Complete Table

Disease	Pathogen	Mode of Transmission
Small Pox	Variola Virus	Air borne
Chicken Pox	Varicella Zoster	Air borne
Measles (Rubeola)	Measles virus	Air borne
Rubella (German measles)	Rubella virus	Respiratory droplets
Influenza	Orthomyxovirus	Air borne
Swine Flu	Influenza A Virus Subtype H1N1	Air borne
Yellow Fever	Flavi Virus	Bite of Aedes aegypti mosquito
Dengue (Break Bone Fever)	Dengue Virus (DENV)	Bite of Aedes aegypti mosquito
Chikungunya	Chikungunya Virus (CHIKV)	Bite of Aedes aegypti mosquito
Poliomyelitis	Poliovirus (Enterovirus C); historically three wild serotypes	Faeco-oral route, usually contaminated food or water
Rabies / Hydrophobia	Lyssa virus type-1	Bite of infected animal (Wolf, Dog, Monkey)
AIDS / Slim disease	Retrovirus HIV (Human Immunodeficiency Virus) \| Test: ELISA	Unsafe sex, Contaminated blood/needles/razor, Mother to foetus

⚠ Exam Trap

The Aedes aegypti mosquito transmits dengue, chikungunya and yellow fever. HIV screening = ELISA. Swine flu = H1N1. Rabies = Hydrophobia (fear of water). India is polio-free; its last wild poliovirus case was in 2011, with regional certification in 2014.

⚡ Quick Recall

HIV-AIDS, HPV, Hepatitis-B = Sexually Transmitted Diseases (STD). COVID-19 = infectious viral respiratory disease caused by SARS-CoV-2; its exact origin remains unproven. Jaundice = a sign of elevated bilirubin with several possible causes.

🧫 Bacterial Diseases — Complete Table

Disease	Pathogen	Mode of Transmission
Tuberculosis (TB)	Mycobacterium tuberculosis	Air borne
Diphtheria	Corynebacterium diphtheriae	Air borne
Whooping Cough (Pertussis)	Bordetella pertussis	Air borne
Pneumonia	Streptococcus pneumoniae	Air borne
Cholera	Vibrio cholerae	Contaminated food and water
Typhoid	Salmonella typhi \| Test: Widal Test	Contaminated food and water
Diarrhoea	Salmonella sp. and E. coli (also Rotavirus)	Contaminated food and water
Plague (Black Death)	Yersinia pestis	Rat fleas
Tetanus (Lock Jaw / 8th Day disease)	Clostridium tetani	Contamination of wound
Leprosy (Hansen's disease)	Mycobacterium leprae	Prolonged close contact with an untreated patient; mainly respiratory droplets

⚠ Exam Trap

Typhoid test = Widal Test. HIV screening = ELISA. Plague = Rat fleas (not mosquito!). Tetanus = Lock Jaw / 8th Day disease. Leprosy = Hansen's disease. Both TB and leprosy are caused by organisms belonging to the genus Mycobacterium.

⚡ Quick Recall

Trachoma = Eye disease → blindness → Chlamydia trachomatis bacteria. Gastritis in stomach → Helicobacter pylori bacteria.

🦟 Protozoan Diseases & Oral Association

Disease	Pathogen	Mode of Transmission
Diarrhoea	Giardia intestinalis	Contaminated water and food
Amoebiasis	Entamoeba histolytica	Contaminated water and food
Oral / periodontal-pocket association	Entamoeba gingivalis — not the sole proven cause of pyorrhoea	Direct oral contact may transfer it
Kala-azar	Leishmania donovani	Bite of Sand fly
Malaria	Plasmodium sp.	Bite of female Anopheles mosquito
African Sleeping Sickness	Trypanosoma gambiense and T. brucei	Bite of Tse-tse fly

⚠ Exam Trap

Malaria = Female Anopheles (NOT male, NOT Aedes). Kala-azar = Sand fly. African Sleeping Sickness = Tse-tse fly. Entamoeba gingivalis is associated with periodontal pockets; it is not the sole proven cause of pyorrhoea.

🪱 Helminthic (Worm) Diseases

Disease	Pathogen	Mode of Transmission
Ascariasis	Ascaris lumbricoides	Consuming contaminated fruits and vegetables
Elephantiasis / Filariasis	Wuchereria bancrofti	Bite of Culex mosquito

⚡ Quick Recall — Mosquito Types Summary

Aedes aegypti: Dengue + Chikungunya + Yellow Fever
Female Anopheles: Malaria
Culex: Elephantiasis / Filariasis

🍄 Fungal Diseases

Disease	Pathogen	Mode of Transmission
Ringworm	Microsporum and Trichophyton	Direct or indirect contact
Candidiasis	Candida	Direct or indirect contact

📌 Important Additional Facts

COVID-19 = infectious viral respiratory disease caused by SARS-CoV-2
The exact origin of SARS-CoV-2 has not been conclusively established; zoonotic spillover remains a leading hypothesis
Jaundice: Yellow skin and sclera due to elevated bilirubin; may occur with liver, biliary or blood-related conditions
Polio = India is polio-free; last wild case in 2011
HIV-AIDS, HPV, Hepatitis-B = Sexually Transmitted Diseases (STD)
Trachoma: Eye disease → blindness; caused by Chlamydia trachomatis
Helicobacter pylori: Causes gastritis in stomach

⚠ Exam Trap

Ringworm is a fungal disease, not a worm infection. Candidiasis is caused by the Candida fungus. Jaundice is a sign of elevated bilirubin; hepatitis is one of several possible causes. Typhoid test = Widal | HIV screening = ELISA; these are different tests.

🦟 Disease Vectors — Master Quick Reference

Vector	Disease(s) Caused	Pathogen
Aedes aegypti (Mosquito)	Dengue, Chikungunya, Yellow Fever	DENV, CHIKV, Flavi virus
Female Anopheles (Mosquito)	Malaria	Plasmodium sp.
Culex (Mosquito)	Elephantiasis / Filariasis	Wuchereria bancrofti
Sand fly	Kala-azar	Leishmania donovani
Tse-tse fly	African Sleeping Sickness	Trypanosoma gambiense / T. brucei
Rat flea	Plague (Black Death)	Yersinia pestis
Dog / Wolf / Monkey bite	Rabies (Hydrophobia)	Lyssa virus type-1

📋 Diagnostic Tests — Quick Reference

Test	Disease Diagnosed
ELISA	HIV screening (traditional exam pairing)
Widal Test	Typhoid

📊 Pathogen-wise Disease Summary

Viral Diseases

Small Pox, Chicken Pox
Measles; Rubella (distinct diseases); Influenza
Swine Flu (H1N1)
Dengue, Chikungunya, Yellow Fever
Polio, Rabies, AIDS

Bacterial Diseases

TB, Diphtheria, Whooping cough
Pneumonia, Cholera, Typhoid
Plague, Tetanus, Leprosy
Trachoma, Gastritis

Protozoan Diseases & Oral Association

Malaria, Kala-azar
Amoebiasis; E. gingivalis (oral association)
African Sleeping Sickness

Fungal & Worm

Ringworm, Candidiasis
Ascariasis, Elephantiasis

⚡ Quick Recall — Mosquito Trick

Aedes = Dengue + Chikungunya + Yellow fever → ADCy
Anopheles = Malaria (only) → Female only bites
Culex = Elephantiasis → CE

🦠 Chapter 10 — Human Disease