CARA'S TIPSCauses, spread, prevention and control of diseases
JAMBWAECNECO
What the syllabus asks
JAMB: meaning and causes; communicable diseases – airborne, water/food-borne, insect-borne, worm infections, animal-borne, contact diseases including STIs and AIDS; prevention and control – immunisation, sterilisation, isolation; non-communicable diseases – hypertension, sickle cell, cancer, epilepsy, ulcer, asthma, diabetes)
WAEC: communicable and non-communicable diseases
NECO: communicable and non-communicable diseases
What you will learn
- Define disease and state its causes.
- Explain the chain of infection and types of immunity.
- Describe airborne, water/food-borne, insect-borne, worm, animal-borne and contact diseases: cause, spread, signs, treatment and prevention.
- Explain HIV/AIDS transmission, testing, treatment and prevention.
- Describe general methods of preventing and controlling communicable diseases.
- Describe hypertension, diabetes, cancer, sickle cell disease, epilepsy, asthma and peptic ulcer.
- Correct common myths about diseases.
Key points
- Disease: impaired function with signs and symptoms; many causes.
- Chain of infection and immunity types.
- Measles (virus, vitamin A, vaccine), whooping cough (pertussis, pentavalent), CSM (meningitis belt, Men vaccines).
- TB (cough ≥2 weeks, free 6-month treatment, BCG); polio (faecal–oral, wild-polio-free 2020).
- Cholera (rice-water stools, ORS), typhoid (blood culture), dysentery (blood and mucus).
- Malaria (Plasmodium, female Anopheles, nets, ACT, R21), yellow fever (Aedes, vaccine), sleeping sickness (tsetse).
- Roundworm, hookworm (bare feet, anaemia), guinea worm (Cyclops; Nigeria free 2013), tapeworm.
- Rabies (dog bite, wash 15 min, PEP), leptospirosis (rat urine, floods), Lassa (Mastomys; dry season).
- Ringworm (fungus), scabies, leprosy (curable); gonorrhoea, syphilis, HIV (ART, U=U).
- Control: immunisation, sterilisation, isolation, quarantine, notification, sanitation, education.
- NCDs: hypertension, diabetes, cancer; risk factors and prevention.
- Sickle cell, epilepsy, asthma, peptic ulcer; myths corrected.
Start here: Disease: meaning, causes and the chain of infection
Disease is any condition that impairs the normal structure or function of the body or mind, producing signs and symptoms. A sign is what others can observe or measure (fever, rash); a symptom is what the patient feels (headache, pain).
Causes of disease
- Pathogens (germs): viruses (measles, polio, HIV, yellow fever, Lassa, rabies), bacteria (cholera, typhoid, TB, meningitis, gonorrhoea, leprosy), fungi (ringworm, thrush), protozoa (malaria, amoebic dysentery, sleeping sickness), worms/helminths (roundworm, hookworm, tapeworm).
- Nutritional: deficiency or excess (kwashiorkor, goitre, obesity).
- Genetic (inherited): sickle cell disease, haemophilia.
- Lifestyle: smoking, alcohol, inactivity, unhealthy diet (hypertension, type 2 diabetes, some cancers).
- Environmental and occupational: pollution, chemicals, radiation, noise.
- Degenerative: wear and tear with age (osteoarthritis, cataract).
- Mental and social factors: stress, depression.
Communicable vs non-communicable
A communicable (infectious) disease is caused by a pathogen and can spread from person to person, from animals or through vectors, water or food. A non-communicable disease (NCD) cannot be passed from person to person; NCDs are usually long-lasting (chronic) and caused by genetics, lifestyle and environment.
The chain of infection
Pathogen → reservoir (infected person, carrier, animal, soil) → portal of exit (coughs, stools, blood) → mode of transmission (droplets, air, water, food, insects, contact, sexual, mother to child) → portal of entry (mouth, nose, skin breaks, genital tract) → susceptible host. Breaking any link stops spread: e.g. vaccination makes hosts immune; handwashing blocks transmission; nets stop the vector.
Immunity
Immunity is the body’s ability to resist infection. Natural active: after having the disease. Artificial active: after vaccination. Natural passive: antibodies from mother via placenta and breast milk. Artificial passive: ready-made antibodies (e.g. rabies immunoglobulin, antivenom). Incubation period: time from infection to first symptoms.
Immunity gained from vaccination is (A) natural active (B) artificial active (C) natural passive (D) artificial passive. Answer: B.
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Practice questions
- Lassa, Borno State
- Lagos
- Kano
- Enugu
Show answer
A: Lassa, Borno State
Named after the town.
- Anopheles mosquito
- tsetse fly
- domestic dog
- multimammate rat (Mastomys natalensis)
Show answer
D: multimammate rat (Mastomys natalensis)
Contamination by rat urine or droppings.
- harmattan only in July
- Christmas week only
- dry season (roughly December–April)
- rainy season only
Show answer
C: dry season (roughly December–April)
WHO/NCDC.
- insulin
- ribavirin
- penicillin
- chloroquine
Show answer
B: ribavirin
Given early in hospital.
- measles
- cholera
- malaria
- typhoid
Show answer
A: measles
Measles is viral.
Key words
- Pathogen
- Disease-causing organism.
- Communicable disease
- Disease that can spread from one host to another.
- Non-communicable disease
- Disease not passed from person to person.
- Vector
- Organism that carries a pathogen.
- Incubation period
- Time from infection to first symptoms.
- Carrier
- Infected person without symptoms who can spread the germ.
- Zoonosis
- Disease passed from animals to humans.
- Immunisation
- Making a person immune, usually by vaccination.
- Herd immunity
- Protection of a community when most people are immune.
- Isolation
- Separating sick infectious people.
- Quarantine
- Restricting exposed healthy people.
- Endemic
- Constantly present in an area.
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