What is it about?
In tropical regions like Port Harcourt, COVID-19 and malaria overlap and both can affect blood clotting, but we don't know how mild cases behave, or if men and women respond differently. We conducted a STROBE-compliant case-control study of 220 adults (55 per group) aged 20-65 years, balanced by sex (22 females and 33 males per group), between November 2021 and March 2022 at Rivers State University Teaching Hospital. The four groups were: healthy controls, malaria-positive, COVID-19-positive (mild/asymptomatic), and co-infected with both. We measured platelet indices using Sysmex XP-300 and D-dimer and fibrinogen by ELISA. The key finding was: • PDW (Platelet Distribution Width) - a measure of variation in platelet size - was significantly elevated in all infected groups vs controls: malaria 15.19 fL, COVID-19 15.17 fL, co-infection 15.58 fL vs control 13.27 fL; F=25.850, p<0.001. • D-dimer - a marker of clot breakdown - was highest in the co-infected group at 552.80 ng/mL. When we looked at sex, there was a significant interaction for fibrinogen and D-dimer, but not for platelet indices. Specifically, PDW was higher in females in malaria (p=0.012) and co-infection (p=0.033), and D-dimer was higher in males only in malaria (p=0.021). No significant correlations were found between platelet and fibrinolytic markers. In simple terms: even mild COVID-19 and malaria leave a measurable fingerprint on the clotting system, and that fingerprint looks different in men and women.
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Photo by Gani Nurhakim on Unsplash
Why is it important?
This is the first sex-stratified analysis of hemostatic responses in mild COVID-19, malaria, and co-infection in a high-burden tropical setting. Why it matters now: 1. Accessible diagnostics for resource-limited settings: PDW is part of a routine full blood count - cheap, fast, and already available in most Nigerian labs. D-dimer is also widely available. Our study shows these two inexpensive markers are informative indicators of hemostatic alterations even when patients are not severely ill. 2. Co-infection risk: Co-infection produced the highest D-dimer levels, indicating a dual impact that could increase thrombosis risk if missed. 3. Sex-specific medicine: Guidelines for COVID-19 and malaria rarely consider sex. We show sex significantly modifies fibrinolytic responses, supporting sex-aware monitoring. 4. Public health in endemic areas: As COVID-19 becomes endemic alongside malaria in Africa, understanding mild disease is crucial for early triage, not just ICU care. For clinicians in Port Harcourt and similar tropical settings, this suggests adding PDW and D-dimer to routine work-up for mild febrile illnesses could help flag patients who need closer follow-up.
Perspectives
As a researcher and clinician based in Port Harcourt, I have seen firsthand how COVID-19 and malaria can present with almost identical early symptoms - fever, malaise, headache - yet we treat them as separate diseases. This work started from a simple observation in our 2021-2022 cohort: platelet counts alone were not telling the whole story. We wanted to look deeper at how platelets were changing (PDW) and what was happening to clot breakdown (D-dimer), and whether being male or female mattered. The persistence of elevated PDW even in mild/asymptomatic cases surprised us. It suggests platelet activation is an early, sensitive event, not just a complication of severe disease. For me, this paper is about bringing precision to tropical medicine - showing that tools we already have (a basic blood count) can be repurposed to understand overlapping epidemics, and that our local data from Nigeria matters for global understanding of post-COVID hemostasis.
Erens Ekprikpo
Rivers State University of Science and Technology
Read the Original
This page is a summary of: Sex-specific hemostatic responses and alterations of Platelet Distribution Width (PDW) and D-dimer in mild COVID-19, Malaria, and co-infection in a tropical setting: A case-control study in Port Harcourt, Nigeria, PLOS Global Public Health, October 2026, PLOS,
DOI: 10.1371/journal.pgph.0007465.
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