Urban Malaria Silently Spreads in Ethiopian Town, Study Finds One in Six Infected

Malaria has long been framed as a rural problem in Africa, a disease of remote villages far from the reach of city clinics and surveillance systems. A new community-based study from Dilla Town in southern Ethiopia challenges that assumption with striking force. Researchers screening 360 ordinary town residents found that roughly one in six carried malaria parasites, a prevalence far higher than most urban health planners would expect. The findings, published in BMC Public Health, suggest that cities and towns across sub-Saharan Africa may be quietly sustaining transmission that national elimination programs are not designed to detect.

The research team, led by Alayu Bogale of Dilla University’s Department of Medical Laboratory Sciences, conducted a community-based cross-sectional study between April and June 2026. Rather than relying on patients who happened to visit health facilities, the investigators went door to door, enrolling participants through multistage systematic random sampling. This design matters because facility-based statistics systematically miss infected people who never seek care, particularly adults with partial immunity who experience mild or asymptomatic infections. By sampling the general population, the study captures the true reservoir of parasites circulating in the community, including the silent infections that fuel ongoing transmission.

The diagnostic strategy combined two complementary techniques. Every participant was first screened by light microscopy using Giemsa-stained blood films, the traditional gold standard that remains the workhorse of malaria diagnosis in most of Ethiopia. In parallel, the team performed multiplex quantitative polymerase chain reaction, or qPCR, a molecular method that amplifies parasite DNA and can detect infections at parasite densities far below the threshold of microscopic detection. The two methods converged on similar answers: microscopy identified malaria in 15.6 percent of participants, with a 95 percent confidence interval of 11.8 to 19.3 percent, while qPCR pushed the estimate slightly higher to 16.9 percent, with a confidence interval of 13.1 to 20.8 percent. The narrow gap between the two figures indicates that most infections in this population were detectable even by conventional microscopy, meaning parasite loads were substantial rather than trace-level.

Perhaps the most consequential finding concerned which parasite species was responsible. Plasmodium vivax, not the notoriously deadly Plasmodium falciparum, was the predominant species in Dilla Town. This distinction carries deep biological and operational implications. Unlike falciparum, vivax parasites can lie dormant in the liver as hypnozoites, reactivating weeks or months after the original mosquito bite to cause relapsing episodes of illness without any new exposure. A vivax-dominated urban epidemic is therefore self-replenishing in a way that makes control harder: each untreated liver infection becomes a future clinical case, and each symptomatic person becomes a source of infection for local mosquitoes. Elimination strategies that focus solely on treating blood-stage infections will repeatedly fail against vivax unless the dormant liver stages are also addressed.

To understand why some residents were infected while others were not, the researchers collected detailed questionnaires covering socio-demographic characteristics, environmental conditions, and preventive behaviors. They then applied multivariable logistic regression, a statistical technique that estimates the independent effect of each factor while holding all the others constant. Four factors emerged as significant predictors of infection at the conventional threshold of p less than 0.05, and together they sketch a coherent picture of how urban malaria takes hold in a growing town.

The strongest behavioral determinant was the failure to sleep under a long-lasting insecticidal net, which nearly tripled the odds of infection with an adjusted odds ratio of 3.12 and a confidence interval of 1.55 to 6.27. Closely related, the simple absence of an insecticide-treated net in the household raised the odds by a factor of 2.83, with a confidence interval of 1.39 to 5.75. These effect sizes are not subtle. In practical terms, a resident without effective net protection faced roughly three times the infection risk of a protected neighbor, even after accounting for income, environment, and other confounders. The result underscores a persistent gap in malaria programming: nets are distributed widely in Ethiopia, but consistent nighttime use in urban settings, where people may perceive mosquito risk as low or where nets are uncomfortable in hot weather, lags far behind ownership.

Poverty also left a measurable biological footprint. Participants from households earning less than 3,000 Ethiopian Birr per month had 2.74 times the odds of infection, with a confidence interval of 1.28 to 5.86. Income shapes malaria risk through multiple pathways: poorer households tend to live in housing with gaps that admit mosquitoes, may lack screens or ceilings, may be unable to afford repellents or repairs, and often occupy the lowest-lying, wettest plots of land. In an urban context, this means malaria maps onto the same socioeconomic gradients that structure so many other diseases, concentrating the burden among families least equipped to prevent or treat it.

The environmental findings may prove the most actionable. Residents living near open drainage channels had 2.97 times the odds of infection, with a confidence interval of 1.50 to 5.86. Open drains in towns like Dilla collect stagnant or slow-moving water during and after the rains, creating exactly the kind of shallow, sunlit breeding habitat favored by urban-adapted Anopheles mosquitoes. This single environmental factor, which is in principle fully modifiable through municipal engineering, carried an association with infection as strong as any behavioral variable in the study. It points toward a control paradigm that differs from rural malaria work: instead of relying almost entirely on nets and indoor spraying, urban programs can target the aquatic habitats themselves through drainage improvement, larval source management, and routine inspection of construction sites and water storage.

The Dilla findings sit within a broader continental trend. Urban malaria is estimated to account for 15 to 20 percent of malaria cases in sub-Saharan Africa, a share that is growing as African cities expand faster than their water and sanitation infrastructure. Urbanization creates ideal conditions for transmission when it outpaces drainage: standing water in drains, ditches, brick pits, and tire tracks; dense human populations that give mosquitoes abundant blood meals; and health systems whose malaria expertise and commodity supply chains are anchored in rural districts. Ethiopia’s national elimination ambitions make this especially urgent, because persistent foci of urban transmission can seed outbreaks into areas where transmission has otherwise been driven down, undermining progress achieved at great cost.

The authors conclude that urban malaria remains a genuine public health concern in Dilla Town and call for strengthened net utilization, environmental management, local surveillance, and targeted vector control. The study was approved by the Institutional Review Board of Dilla University College of Medicine and Health Sciences, with written informed consent obtained from all participants or their guardians, and infected participants were referred to nearby health facilities for treatment. The work was funded by Dilla University with cooperation from the Gedeo Zone Health Department and local municipal authorities. Its central message extends well beyond one southern Ethiopian town: as Africa urbanizes, elimination strategies built exclusively for rural transmission will keep missing the parasites hiding in plain sight, in city drains, in low-income neighborhoods, and in the livers of townspeople who never realized they were infected.

Subject of Research: Urban malaria prevalence and risk factors in Dilla Town, southern Ethiopia

Article Title: Prevalence and determinants of urban malaria among urban residents of Dilla Town, southern Ethiopia: a community-based cross-sectional study

Article References: Bogale, A., Mitiku, A., Amdiyee, A. A., Molla, E., Terefe, H., Abebe, W., & Deres, A. (2026). Prevalence and determinants of urban malaria among urban residents of Dilla Town, southern Ethiopia: a community-based cross-sectional study. BMC Public Health. https://doi.org/10.1186/s12889-026-29739-2

Image Credits: AI Generated

DOI: 10.1186/s12889-026-29739-2

Keywords: urban malaria, Plasmodium vivax, Ethiopia, cross-sectional study, insecticide-treated nets, qPCR, public health, vector control, epidemiology, open drainage, malaria elimination, socioeconomic determinants