What We DoIssuesGlobal HealthGlobal Health Resource CenterFrom Home Visits to Health Intelligence: How Community Health Workers Track Disease in Real Time
Written by: Molly Moss, United Nations Foundation
In many settings around the world, community health workers (CHWs) are the connective tissue of strong health systems. They are trusted neighbors, service providers, and the first to notice emerging health threats. In a world grappling with both ancient diseases and newly emerging ones, their role in detecting outbreaks of infectious diseases remains vital to global health security.
What makes CHWs so effective is not only what they know, but also who they know. Josephine Barasa, a community health worker in Nairobi, Kenya, knows a lot of people. Perhaps more importantly, a lot of people know her.
“When there is an outbreak or there is something new affecting the community, I get phone calls in the night, or very early in the morning…This always happens because I am in good relations with the people around, and they have trust with me.”
Neighbors go directly to her for guidance. Parents call when two or three children develop high fever. They alert her when diarrhea spreads through a household. These interactions are not incidental – they are the human infrastructure that detects disease in community settings.
Describing her own neighborhood in the Central Business District of Nairobi, Josephine explains that trust is built over time, through home visits, late-night calls, and shared lived experiences. “In every community where we have community health workers, they will be the first to spot anything unusual,” she says. “Those who have good rapport and trust with the community will get to know about it very fast.”
Through routine door-to-door visits, CHWs develop a granular understanding of community health patterns. They notice when something shifts: a cluster of rashes among children, a sudden uptick in coughs, or diarrheal illness after heavy rains. This early awareness is critical for triggering a timely response from the health system. Whether Josephine is seeing the first few cases of a fast-moving cholera outbreak, or the possible arrival of malaria cases from rural counties, her home visits are often the first flag that something is amiss.
Following the COVID-19 pandemic, it has become increasingly clear that trust is not a soft concept. It is a measurable characteristic that influences behavior, including whether people seek out medical care when they develop symptoms. As trust in institutions erodes, the role of CHWs as the reliable interface between communities and health systems becomes even more important.
A community health worker often acts as a bellwether for new trends, picking up signals about emerging diseases before formal data systems catch up. Josephine says, “In the rainy season in my community, we will always get diarrhea. The drainage system floods and water pipes get contaminated. Two to three days after it rains, we get cases of diarrhea.”
These observations are not just anecdotal; they are also predictive, and they help more formal health facilities prepare to meet the actual burden of disease at any moment. Through an application on her mobile phone called the Electronic Community Health Information System (eCHIS), Josephine tracks the symptoms of each patient she sees. She notes diarrheal disease following rains, respiratory infections during colder months, and eye infections in the dusty, dry season.
From these observations, CHWs can activate timely and appropriate responses from a health facility but also identify an unusual pattern. The process is both simple and sophisticated. A CHW finds a symptomatic individual, conducts an initial assessment – checking temperature, documenting symptoms – and provides immediate care when possible.
“I write in my phone the household and the temperature, which I check two to three times at 30-minute intervals…Then this report is reflected in the health facility the next day,” Josephine explains. The kind of real-time, community-level epidemiologic data generated by Josephine is invaluable. It is an early alert that allows health systems to anticipate, not just react. Her reporting to eCHIS also serves as a patient referral that allows families to receive treatment from the local facility that Josephine is not equipped to provide in the home.
The digital tools that Josephine uses are critical enablers of her work. The eCHIS app is a central component of Kenya’s 2020–2025 digitization strategy, replacing paper registers to improve data accuracy, referral systems, and supply chain management for community-level care. Across 47 counties, more than 100,000 CHWs like Josephine have been equipped with smartphones to improve reporting on community health services, collect field data, and enhance emergency preparedness.
The flow of information from household to CHW to clinic creates a continuous feedback loop because CHWs don’t stop at referral. They follow up. Josephine says, “I will do a check later to ensure they went to the facility, got the services and medication they required, and I offer follow-up support.” This accountability ensures that suspected cases – whether cholera, typhoid, or HIV – are not lost between detection and treatment. It also strengthens the credibility of the system itself.
While Josephine is a crucial line of defense for responding to acute outbreaks, she is equally engaged in managing endemic diseases, particularly HIV and tuberculosis. Her work often intersects with complex social challenges in environments that facility-based health systems struggle to reach. Among adolescent girls, for instance, rising HIV cases are deeply entangled with poverty and unemployment, gender-based violence, and mental health challenges. “At times, it [the poverty] is beyond us. The environment is very toxic. Every day, I come across one case of a girl who is infected with HIV and is pregnant,” she says. “This is a very critical area, and we need to invest in our CHWs to look into these cases.” As a CHW, Josephine frequently encounters cases shaped by trauma and inequality. Her role demands not only clinical vigilance but emotional resilience.
The broader determinants of health impact Josephine’s work in other ways as well. In the dry months, Josephine’s community faces extremely limited access to water, which means handwashing and food preparation become impossible, fueling the risk of outbreaks of diseases like cholera and typhoid. Population movement also plays a role. While malaria is rare in central Nairobi, CHWs identify cases among migrants coming to the city from endemic regions, adding a critical layer of context to their role in disease surveillance.
Yet, Josephine doesn’t always have the tools required to meet the needs of her community. She wishes that she could carry rapid diagnostic tests for HIV and malaria, as well as glucose testing kits to screen for diabetes. Without these reliable and generally affordable diagnostic tools, CHWs must rely heavily on symptoms. This can delay case confirmation and treatment, both of which are critical for containing the spread of disease effectively. The story of one close call underscores what is at stake: “I recently came across [a situation] where a woman was diagnosed with typhoid and malaria. By the time she had these tests done, she was malnourished.” Josephine referred her to the hospital for treatment and the woman is now recuperating. “I thought maybe if I had the tools, I could have saved this mom’s life in better time.”
As global health leaders consider the future of pandemic preparedness and health system resilience, it should be clear that while surveillance exists in labs and ministries, it begins in homes, through trusted relationships and everyday interactions. Investing in CHWs means equipping them with the diagnostics and digital tools they need to act decisively. It also means expanding access to training programs to help professionalize the workforce. In Nairobi, training is offered by partners like WHO and UNICEF on an ad hoc basis, and while valuable, they often reach only a subset of CHWs, leaving others without up-to-date knowledge.
Understanding the impact of CHWs means recognizing their broader role in the communities they serve. They are not just healthcare providers. They are also advocates, counselors, and change-makers. CHWs are doing the work – detecting outbreaks, linking patients to care, and holding communities together in the face of uncertainty. CHWs like Josephine are part of a precious network of people who act early and act often to protect lives in their communities and around the world.
Last updated: April 22, 2026
Molly Moss is a Director of Global Health at the United Nations Foundation, where her work focuses at the intersection of public health and international affairs. Based in New York City, Molly collaborates with UN Member States on a range of health policy issues, including antimicrobial resistance, Universal Health Coverage, pandemic preparedness, and health financing reform. She also writes extensively about governance issues emanating from World Health Organization in Geneva. In both New York and Geneva, she works closely with global health experts and advocacy partners to translate scientific knowledge and evidence into actionable and ambitious policy. Prior to the United Nations Foundation, Molly worked for the Center for Global Health at the University of Colorado, where she focused on immunization, neonatal survival, and research ethics. During her time there, Molly earned her Master of Public Health; she also holds a bachelor’s degree in medical anthropology from Hampshire College. Molly is currently an instructor in the Department of Global Health, Milken Institute School of Public Health at the George Washington University.
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