discuss the biological, social and economic factors that need to be considered in the prevention and control of cholera, malaria, TB and HIV (details of the life cycle of the malarial parasite are not expected)

Infectious Diseases – Prevention and Control

This note outlines the biological, social and economic factors that must be considered when preventing and controlling four major infectious diseases: cholera, malaria, tuberculosis (TB) and HIV.

1. Cholera

Biological Factors

• Caused by Vibrio cholerae* (serogroups O1 and O139).
• Transmission is faecal‑oral, usually via contaminated water or food.
• Rapid onset of profuse watery diarrhoea leads to severe dehydration.
• Environmental survival is enhanced in warm, brackish waters.

Social Factors

• Inadequate sanitation and lack of safe drinking water.
• Population displacement (e.g., refugees, natural disasters) increases exposure.
• Low public awareness of hygiene practices.
• Cultural practices that involve communal eating or water sharing.

Economic Factors

• Poor infrastructure investment in water treatment and sewage systems.
• High cost of oral rehydration salts (ORS) and intravenous fluids in low‑income settings.
• Loss of productivity due to illness and mortality.

Prevention & Control Strategies

1. Provision of safe drinking water (chlorination, filtration).
2. Improvement of sanitation (latrines, sewage treatment).
3. Health education on hand‑washing and safe food handling.
4. Rapid case detection and treatment with ORS and antibiotics when indicated.
5. Vaccination (e.g., killed‑cell oral cholera vaccine) in high‑risk areas.

2. Malaria

Biological Factors

• Transmitted by female Anopheles mosquitoes infected with Plasmodium spp.
• Key species causing severe disease: P. falciparum and P. vivax.
• Vector breeding requires stagnant freshwater with sunlight.
• Drug resistance (e.g., artemisinin resistance) impacts treatment efficacy.

Social Factors

• Living in endemic rural or peri‑urban areas with limited access to health services.
• Use of traditional sleeping arrangements that do not accommodate bed nets.
• Migration of workers to endemic zones.
• Community acceptance of indoor residual spraying (IRS).

Economic Factors

• Cost of insecticide‑treated nets (ITNs) and IRS programmes.
• Economic burden of lost work days and school absenteeism.
• Funding for surveillance and rapid diagnostic testing.

Prevention & Control Strategies

1. Distribution of ITNs and promotion of proper use.
2. Indoor residual spraying with WHO‑approved insecticides.
3. Environmental management to eliminate mosquito breeding sites.
4. Prompt diagnosis with rapid diagnostic tests (RDTs) and effective antimalarial therapy.
5. Surveillance for drug‑resistant parasites and vector resistance.

3. Tuberculosis (TB)

Biological Factors

• Caused by Mycobacterium tuberculosis, an intracellular pathogen.
• Transmission via aerosolised droplets from individuals with active pulmonary TB.
• Latent infection can reactivate when immunity wanes.
• Multidrug‑resistant (MDR) and extensively drug‑resistant (XDR) strains complicate treatment.

Social Factors

• Overcrowded living conditions and poor ventilation.
• Stigma associated with TB discourages health‑seeking behaviour.
• Co‑infection with HI \cdot increases susceptibility.
• Limited awareness of cough etiquette and infection control.

Economic Factors

• High cost and long duration of standard TB therapy (6‑9 months).
• Economic impact of lost income during treatment.
• Resource constraints for laboratory diagnostics (e.g., GeneXpert).

Prevention & Control Strategies

1. Active case finding and contact tracing.
2. Directly observed therapy (DOT) to ensure treatment adherence.
3. Vaccination with BCG in high‑risk newborns.
4. Improving ventilation in homes, schools and workplaces.
5. Integration of TB and HI \cdot services.

4. Human Immunodeficiency \cdot irus (HIV)

Biological Factors

• Retrovirus that targets CD4⁺ T‑lymphocytes, leading to immunodeficiency.
• Transmission through sexual contact, blood, perinatal exposure, and sharing of needles.
• High mutation rate results in diverse viral subtypes and drug resistance.
• No cure; lifelong antiretroviral therapy (ART) required.

Social Factors

• Stigma and discrimination hinder testing and treatment uptake.
• Gender inequalities affect negotiation of safe sex practices.
• Key populations (sex workers, men who have sex with men, intravenous drug users) face legal and social barriers.
• Lack of comprehensive sex education.

Economic Factors

• Cost of lifelong ART and monitoring (viral load testing).
• Economic loss from reduced workforce participation.
• Funding gaps in low‑ and middle‑income countries for prevention programmes.

Prevention & Control Strategies

1. Universal access to HI \cdot testing and counselling.
2. Provision of ART to all diagnosed individuals (treatment as prevention).
3. Pre‑exposure prophylaxis (PrEP) for high‑risk groups.
4. Promotion of condom use and safe injection practices.
5. Community‑based education to reduce stigma.

Comparative Summary