10.1.310-11 · Infectious Disease and Immunity

Prevention and Control of Disease — Cambridge AS & A Level Biology 9700 Revision Notes & Topical Questions

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📚 Cambridge AS & A Level Biology 9700 Hub / Topical Revision

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10.1.3 Prevention and Control of Disease — CAMBRIDGE AS & A LEVEL BIOLOGY 9700 — REVISION NOTES notes: Describe and evaluate the measures used to prevent and control cholera, malaria, TB, HIV/AIDS, measles, smallpox and BSE.Aim — control strategies break the chain of transmission…

Approaches
Requirements
Why it persists
Long-term solution
Where it spreads
Reduce bites

Part 1 of 10Principles of control

Aim

Aim control strategies break the chain of transmission at its weakest point.

Approaches

Approaches improve hygiene, sanitation and water supply;
- control the vector or reservoir;
- vaccinate;
- treat and isolate the infected;
- educate the public;
- monitor and trace cases.

Requirements

Requirements political will, money, infrastructure and community cooperation.

Part 2 of 10Cholera

Why it persists

Why it persists it occurs where sanitation and clean water are lacking.
Fast-growing cities may lack drainage, sewage treatment and clean water, and have limited funds.
Wars and natural disasters destroy infrastructure and crowd people into temporary housing.
Raw sewage is sometimes used to irrigate crops.

Prevention

Prevention adequate sewage treatment, clean chlorinated piped water, hand washing, thorough cooking, and vaccination programmes where it is common.

Control

Control ready access to oral rehydration therapy, WHO monitoring, and antibiotics in severe cases.
- (glucose, salts and water)

Long-term solution

Long-term solution engineering and infrastructure, since poverty is the main cause.

Part 3 of 10Malaria

Where it spreads

Where it spreads regions where Anopheles can breed, which need a warm climate and standing water.

Reduce mosquito numbers.

Spray living areas with insecticides.
Spread oil over water where they breed.
Drain marshes and unnecessary water.
Stock ponds and ditches with larvae-eating fish.

Reduce bites

Reduce bites sleep under bed nets and avoid exposed skin at dusk.
- (soaked in insecticide)

Drugs

Drugs chloroquine and mefloquine taken before, during and after a visit to a malarial area.
Resistant strains of Plasmodium have evolved.
The drugs are expensive and can have unpleasant side-effects.

Vaccination difficulty

Vaccination difficulty the parasite shows antigenic variation, has several life-cycle stages and hides inside cells.

Resistance

Resistance insecticide and drug resistance are spreading.

Combined approach

Combined approach early diagnosis and treatment, indoor residual spraying, removing standing water and larvae-eating fish.
Combination therapy replaced older drugs such as chloroquine because of resistance.

Part 4 of 10Tuberculosis

Treatment

Treatment directly observed treatment with several antibiotics for six months or longer, so resistant strains are not selected.

Spread control

Spread control contact tracing, improved housing and the BCG vaccine.
- (limited effectiveness in adults)

Bovine TB

Bovine TB routine testing and destruction of infected cattle, pasteurising milk and cooking meat properly.

Part 5 of 10HIV/AIDS

Education

Education safer sex, condoms, and tests to encourage knowledge of status.

Needles

Needles needle exchange programmes and no sharing.

Blood

Blood screening and heat treatment of donations.

Drugs

Drugs antiretrovirals reduce viral load and the chance of transmission, including mother to baby.

Birth and feeding

Birth and feeding caesarean delivery and avoiding breastfeeding where there is a safe alternative.

No vaccine

HIV mutates rapidly and attacks the immune system.

Part 6 of 10Viral and prion diseases

Measles

Measles vaccination with MMR;
- because it is so infectious, about 95 per cent coverage is needed for herd immunity,
- and outbreaks occur when coverage drops.

Smallpox

Smallpox global eradication by 1980 was possible because of several advantages.
It had no animal reservoir.
Symptoms were obvious.
The virus was antigenically stable, so one vaccine worked.
The vaccine was cheap and stable.
Teams used ring vaccination of contacts of cases.

BSE

BSE measures were a ban on feeding meat-and-bone meal to cattle, slaughter of infected herds, a ban on nervous tissue of older cattle in the human food chain,
- and testing.
There is no treatment for vCJD.

Part 7 of 10Evaluating strategies

Strategy	Advantage	Limitation
Vaccination	Protects individuals and the population	Not available for all diseases; cost; refusal
Antibiotics or drugs	Cure the sick, reduce spread	Resistance; cost; viruses unaffected
Sanitation and clean water	Prevents many diseases at once	Expensive infrastructure
Vector control	Reduces malaria spread	Resistance; environmental harm

Part 8 of 10Evaluation points

Evaluation points

Format

Format give at least one benefit and one limitation for the named pathogen.

DDT

DDT it reduced malaria, but mosquitoes evolved resistance by natural selection and DDT accumulates in food chains.

Bed nets

Bed nets they are cheap with few side effects but need correct use and replacement.

No single measure

No single measure consider cost, ease of use, speed, environmental impact and the risk of resistance.

Long-term versus short-term

Long-term versus short-term improved housing and education work with drugs and vaccines.

Vaccines

Vaccines where one is available it is usually the most cost-effective option.

Epidemiology terms

Epidemiology terms surveillance records cases, a reservoir is where a pathogen persists, and an epidemic is a sudden rise in cases in a region.

Part 9 of 10More from the specification

Part 10 of 10More on this topic

Unnecessary use

Unnecessary use antibiotics are prescribed for viral infections or minor illnesses.

Sensible use

Sensible use it extends the working life of every drug.

Key terms

Term	Meaning
Herd immunity	Protection of the unvaccinated when most of a population is immune.
Ring vaccination	Vaccinating the contacts of cases to contain spread.
Oral rehydration therapy	A solution of glucose, salts and water that treats dehydration.
Surveillance	Recording the number of cases of a disease.
Epidemic	A sudden rise in cases in a region.
Prophylaxis	Preventive drug use, such as antimalarials taken by travellers.

Avoid these mistakes

Saying one control measure is enough — control needs several strategies together.

Saying a vaccine is available for malaria and HIV like measles — HIV has none and malaria vaccines are recent.

Saying DDT has no drawbacks — resistance evolves and it accumulates in food chains.

Saying herd immunity needs everyone vaccinated — for measles about 95 per cent is needed.

Last updated: 18 October 2026