Early Detection for Rapid Response: Strengthening Disease Surveillance Across West Africa

By The Global Fund

August 14^th, 2025

Header image: The Global Fund/Sylvain Cherkaoui/Panos

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In the heart of Bissau, Guinea-Bissau’s capital city, Cunna Mendes holds a medical cooler filled with biological samples. These were collected from patients showing signs of fever and respiratory distress on the remote island of Bolama, located several hours away by boat.

For Mendes, these samples could be clues to detect a potentially dangerous disease outbreak.

A former nurse and now the regional director of Bolama’s Health District, Mendes is part of a growing network of frontline responders trained to monitor and report early warning signs of disease outbreaks.

“Failing to diagnose an illness is extremely dangerous,” she says. “That’s how outbreaks spread – just like we saw with Ebola and COVID-19.”

Cunna Mendes, Regional Director of Bolama Health District, Guinea Bissau. The Global Fund/Sylvain Cherkaoui/Panos

Efforts to strengthen disease surveillance in Guinea-Bissau are rooted in a powerful regional model developed in Senegal: the Sentinel Syndromic Surveillance System, known as the 4S Network.

Launched by Senegal’s Ministry of Health and the Institut Pasteur de Dakar more than a decade ago, the system is designed to detect emerging health threats early through real-time case-based syndromic data collection and laboratory confirmation, enabling rapid public health responses including clinical care as appropriate.

Dr. Aliou Barry and colleagues at the Institut Pasteur de Dakar, Senegal. The Global Fund/Ricci Shryock

One of the many times the 4S model proved its value was in October 2022, when Senegal experienced a surge in childhood respiratory infections at an unusual time of year. Clinicians across 38 sentinel health facilities, equipped with the digital Teranga (WALIP) platform, reported a spike in undiagnosed cases. Within 24 hours of receiving samples, scientists at the Institut Pasteur de Dakar identified the cases as respiratory syncytial virus-B (RSV-B).

Thanks to early detection, public health officials mobilized swiftly – keeping children out of intensive care, minimizing disruptions to daily life and ultimately saving lives.

Early Detection for Rapid Response: Strengthening Disease Surveillance Across West Africa

Scaling Senegal’s Proven Surveillance Model

Through the West African Regional Laboratory Initiative (WARIL), the Global Fund is working to build upon the 4S model by establishing similar surveillance activities across West Africa – including in Guinea-Bissau, Benin, Sierra Leone and Togo, with plans to include Burkina Faso next year.

WARIL is supported by the Global Fund’s Laboratory Systems Integration Fund, which receives funding from partners including the Rockefeller Foundation, the Abbott Fund and IQVIA through (RED).

“The Laboratory Systems Integration Fund is crucial to expand regional capacities to detect and control disease outbreaks across West Africa,” says David Franks, Vice President, Global Health, IQVIA. “Our partnership with (RED) and the Global Fund reflects our strategic commitment to partnerships addressing some of the biggest challenges facing global health and enhancing global health security and pandemic preparedness. This partnership is a step towards a safer, more prepared and healthier world.”

Other partners including the Gates Foundation and the Africa Centers for Disease Control and Prevention have also collaborated with national authorities to expand the network even further – setting up sentinel surveillance sites in Cabo Verde, The Gambia, Guinea, Mali, Mauritania and Niger.

Dr. Aliou Barry of the Institut Pasteur de Dakar says the network’s expansion beyond Senegal is vital to regional health security:

“For West Africa to be truly protected, every country needs a strong surveillance system. A weakness in one country can put the whole region at risk.”

Dr. Aliou Barry of the Institute Pasteur Dakar, Senegal. The Global Fund/Ricci Shryock

Transforming Diagnostic and Surveillance Systems in Guinea-Bissau

In Guinea-Bissau, WARIL is helping to build the country’s surveillance system from the ground up.

For years, Guinea-Bissau lacked the tools to detect diseases locally, relying on regional reference laboratories to process samples. “Sometimes samples sat in the fridge for days. I had no reagents. No diagnostic tools,” says Sabado Gomes, a laboratory technician at the molecular biology unit of the national reference laboratory in Bissau.

Today, things have changed.

Through WARIL, Guinea-Bissau now operates two sentinel sites – Bairro Militar in Bissau and São Domingos near the Senegal border – chosen for their high patient volume and strategic locations.

Every day at each sentinel site, health workers track and log the number of patients showing symptoms such as fever, cough and diarrhea. This data is shared with health authorities in real time via the Teranga platform, which provides reliable information for rapid decision-making.

Instead of having to send the samples all the way to Dakar, laboratory technicians can now identify arboviruses including yellow fever and Dengue. This saves time and resources and allows local officials to respond rapidly when needed.

For Sidonia Vieira, who leads Guinea-Bissau’s national surveillance team, the sentinel system is a game-changer.

“We have built a centralized system to track cases, share information and coordinate our response,” she says. “Our ability to protect our people is strengthened, giving us both the confidence and the capacity to respond effectively.”

Through WARIL, 23 health workers – including nurses and laboratory technicians – have been trained to detect early signs of arboviral infections and respiratory illnesses and report them using clear, standardized protocols.

In Bairro Militar alone, over 100 community health workers have been trained to actively monitor health events at the grassroots level. These frontline workers serve as a vital bridge between communities and the formal health system – identifying symptoms early, referring patients for care, and raising awareness about how to prevent the spread of disease. In Guinea-Bissau and other countries across West Africa, investments made in expanding the 4S network have already proved their worth, detecting numerous viral pathogens including dengue, chikungunya, Lassa fever and Crimean-Congo hemorrhagic fever. These investments are allowing authorities to act rapidly and keep people everywhere more secure from future disease outbreaks.