South Africa is on the frontlines of climate change, with extreme weather events like devastating floods and prolonged droughts becoming more frequent and intense. A groundbreaking systematic review led by researchers from the University of KwaZulu-Natal (UKZN) has uncovered emerging patterns linking these events to spikes in infectious disease outbreaks, highlighting a critical public health challenge that demands urgent attention from policymakers, healthcare providers, and communities alike.

The study, published in Frontiers in Public Health on March 16, 2026, analyzed 14 peer-reviewed papers from 2014 to 2024, revealing how floods contaminate water sources leading to waterborne illnesses, while droughts disrupt access to clean water and medication for chronic conditions like HIV, exacerbating vulnerability to infections. This research from UKZN's Discipline of Public Health underscores the pivotal role South African universities play in tackling climate-health intersections.

🌊 Understanding the Mechanisms: How Extreme Weather Fuels Disease Spread

Extreme Weather Events (EWEs), defined as unusual or severe meteorological phenomena such as heavy rainfall, floods, droughts, and heatwaves, alter environmental conditions in ways that favor pathogen proliferation. In South Africa, where climate variability is amplified by El Niño-Southern Oscillation (ENSO) patterns like La Niña, these events create ideal breeding grounds for vectors and contaminate water supplies.

The review identifies three main pathways: (1) hydrological changes from floods mobilizing pathogens into water sources; (2) temperature and humidity shifts boosting vector populations like mosquitoes for malaria; and (3) socio-economic disruptions increasing overcrowding and poor sanitation in informal settlements. For instance, post-flood stagnant water becomes a mosquito paradise, while damaged infrastructure hinders sanitation.

South Africa's unique context—high HIV prevalence, dense urban informal settlements, and rural vulnerabilities—amplifies these risks. Children under 5, the elderly, pregnant women, and those with comorbidities face the highest threats, as noted in studies from Limpopo and Western Cape provinces.

📊 Key Diseases Linked to EWEs: Diarrhoeal, Malaria, and Respiratory Infections

The UKZN-led analysis synthesizes evidence on waterborne diseases like cholera, typhoid, leptospirosis, and E. coli dominating post-flood scenarios. Bacterial enteropathogens such as enterotoxigenic E. coli (ETEC) show strong correlations with rainfall and soil moisture.

• Diarrhoeal diseases: Hospital admissions spike in children under 5 after heavy rains, often used as proxy via anti-diarrhoeal sales across 9 provinces.
• Malaria: A 30-day lag after high temperature and rainfall in Limpopo, with vector breeding in flood pools.
• Pneumonia and respiratory infections: Overcrowding in shelters post-disaster drives cases.
• Drought effects: Reduced HIV antiretroviral adherence leads to opportunistic infections; unsafe water sources fuel gastrointestinal issues.

Despite these associations, the review laments a lack of laboratory-confirmed pathogen data post-EWE, relying instead on clinical surveillance.

💧 Case Study: 2022 KwaZulu-Natal Floods and Lingering Health Threats

The April 2022 floods in KwaZulu-Natal (KZN) stand as South Africa's deadliest climate disaster, with over 435 fatalities, thousands displaced, and widespread infrastructure damage. Torrential rains dumped 500mm in days, contaminating water supplies and prompting fears of cholera and leptospirosis outbreaks.

Although no massive confirmed cholera wave materialized, diarrhoeal cases surged, and malaria risks escalated due to stagnant waters. UKZN researchers highlight how such events disproportionately hit informal settlements like those in Durban, where poor sanitation amplified contamination risks. This disaster exemplifies the review's call for better post-EWE surveillance.

Recent 2026 floods in Limpopo and Mpumalanga have reignited concerns, with malaria cases up 355% in Mpumalanga alone.

Photo by National Cancer Institute on Unsplash

🏫 South African Universities Leading the Charge in Climate-Health Research

UKZN's Discipline of Public Health, home to lead authors Prof Saloshni Naidoo and Dr Nisha Nadesan-Reddy, is at the forefront. Naidoo heads the R46.5 million NIHR-funded WEATHER project, piloting AI-driven early warning systems in eThekwini and Ugu districts to predict floods and health risks like waterborne diseases.Learn more about WEATHER

University of Pretoria (UP) partnered with Cornell University in 2024 to launch the Centre for Transformative Infectious Disease Research on Climate, Health, and Equity (C-CHANGE), focusing on vector-borne diseases and zoonoses amid climate shifts.

University of Cape Town (UCT)'s Climate Change and Health hub integrates research on adaptation strategies, emphasizing co-benefits for infectious disease control. These initiatives position SA universities as global leaders in climate-resilient public health.

🛡️ Vulnerabilities and Policy Gaps Exposed

Marginalized communities bear the brunt: 60% of SA's population in informal areas lack sanitation, making them prime for post-flood outbreaks. HIV prevalence (13.9%) compounds risks during droughts when clinics close. The review critiques fragmented surveillance, urging wastewater monitoring and genomic pathogen tracking.

Policy levers include National Climate Change Response Policy enhancements, but gaps in environmental microbiology persist. UKZN's Naidoo emphasizes community empowerment via apps and SMS alerts in WEATHER.

🔮 Future Outlook: Predictions and Proactive Measures

With SA facing more La Niña-driven floods, models predict rising malaria in Limpopo and diarrhoeal burdens nationwide. The review calls for longitudinal studies and AI predictive tools, aligning with UKZN's WEATHER and UP's C-CHANGE.

Actionable insights: Invest in resilient infrastructure, train health workers in climate surveillance, and foster uni-government partnerships. Early warning systems could cut outbreak impacts by 30-50%, per global analogs.

📈 Broader Trends and Statistics

Post-2022 KZN floods, diarrhoeal admissions rose; 2023-2024 cholera hit SA hard amid rains. Recent 2026 floods: 4320 cholera cases regionally, SA on alert. Malaria up 355% in Mpumalanga.

Photo by Brett Jordan on Unsplash

• Floods: Cholera risk from E.coli, vibrio.
• Droughts: 20% drop in HIV adherence.
• Heat: Respiratory spikes.

💡 Solutions from SA Academia: Building Resilience

UKZN's WEATHER uses AI for flood predictions, SMS alerts to vulnerable areas.WEATHER project details UP-Cornell models vector risks.C-CHANGE centre

Recommendations: Wastewater surveillance, genomic sequencing, community education. Unis like UKZN train next-gen researchers for these challenges.

South African universities like UKZN are pivotal in bridging climate science and public health, turning research into actionable resilience. As EWEs intensify, their work promises healthier futures amid uncertainty. Explore opportunities in climate-health research at SA institutions.