The patient, who had been working in Malaysia, first fell ill with intermittent fever during his period of immigration there. Screening at that stage returned a positive result for dengue, a diagnosis that seemed unremarkable in a region where the dengue virus circulates intensely. Yet the fever refused to settle. Dengue is typically a self-limited, mosquitoborne viral illness in which the nonstructural protein 1, or NS1, antigen circulates in blood during the acute phase and clears within days to a couple of weeks as the immune response takes hold. In this patient, however, the fever persisted long enough that he was forced to return to Nepal, carrying with him a dengue label that would shape every subsequent clinical decision.

Back in South Asia, the diagnostic journey grew more tangled rather than less. During evaluation in India, clinicians confronting the patient’s prolonged febrile illness and laboratory abnormalities turned their suspicion toward a hematological malignancy, an understandable but ultimately erroneous interpretation. Visceral leishmaniasis, caused by the protozoan parasite Leishmania donovani and transmitted by phlebotomine sand flies, is famous for mimicking other conditions: it produces splenomegaly, hepatomegaly, pancytopenia, weight loss, and relentless fever, a constellation that can indeed resemble lymphoma or leukemia on superficial review. The misdirection meant that the true diagnosis remained unmade while the underlying parasitic infection continued its indolent destruction of the patient’s immune defenses.

It was only after a third discrete febrile episode that visceral leishmaniasis was finally identified. By that point, however, the case had acquired another layer of complexity: the dengue NS1 antigen was still detectable, a strikingly prolonged persistence for a protein that normally vanishes as acute infection resolves. The reporting team argues that the concomitant infections appear to have driven this prolonged persistence of dengue features and, in parallel, may have propelled a previously asymptomatic Leishmania infection into symptomatic, life-threatening visceral disease. The immunology of such an interaction is plausible if speculative: dengue and Leishmania both manipulate mononuclear phagocytes, and the profound cell-mediated immunosuppression of active visceral leishmaniasis could plausibly impair clearance of viral antigens, while the viral insult could tip a controlled parasitic infection toward clinical manifestness.

Treatment brought the next setback. The patient received liposomal amphotericin B, or LAMB, the recommended first-line therapy for visceral leishmaniasis in many endemic settings, prized for its potency against Leishmania parasites sequestered in the spleen, liver, and bone marrow. Six doses were administered, yet the patient demonstrated no adequate response. Relapse followed the initial course, an outcome that forced the clinical team to reconsider both the diagnosis and the therapeutic strategy. Drug failure in visceral leishmaniasis can arise from host immunosuppression, parasite resistance, inadequate drug exposure, or an incorrect initial diagnosis, and in a patient whose dengue serology remained abnormal, every one of those possibilities demanded attention.

The decisive moment in the odyssey arrived through careful serial testing. When repeat assays for dengue NS1 antigen, dengue-specific IgM, and dengue-specific IgG all finally returned negative results, the diagnostic fog began to lift. With the dengue infection definitively behind him and active visceral leishmaniasis confirmed as the driver of his ongoing febrile illness, the clinicians turned to miltefosine, an oral alkylphosphocholine originally developed as an anticancer agent and later repurposed as a leishmanicidal drug. The intervention proved highly effective: the patient’s visceral leishmaniasis resolved, closing a clinical narrative that had spanned Malaysia, India, and Nepal and involved misdiagnosis, failed therapy, and relapse along the way.

The case carries technical lessons that extend well beyond one patient. Rapid diagnostic tests for dengue, including NS1 antigen detection and IgM/IgG antibody assays, are cornerstones of febrile illness triage in low- and middle-income countries, but their performance assumes a typical immunocompetent, monoinfected host. When a second pathogen remodels the immune landscape, antigen clearance kinetics can change in ways that no single test anticipates. Conversely, the rK39 rapid diagnostic test for visceral leishmaniasis, which the authors highlight among their keywords, detects antibodies that may be absent early or inconsistent across the disease course. A febrile traveler or migrant whose work history spans multiple endemic regions therefore represents a diagnostic worst case for panel-based, single-pathogen thinking, and the authors argue that the case demonstrates a clear need for better diagnostic tools and management strategies specifically designed for coinfections.

Epidemiologically, the report sits at the intersection of two burdens of the same geography. Visceral leishmaniasis remains endemic in the lowland plains of Nepal, India, and Bangladesh, where elimination programs have driven incidence down but not to zero, and dengue has expanded dramatically across the same territories in recent decades, with Nepal experiencing increasingly large seasonal epidemics. Migrant workers such as this patient, who move between endemic countries for employment, occupy a distinctive risk niche: they may acquire one infection in one country, carry it across borders, and have it diagnosed or misdiagnosed in another, fragmenting the clinical record that any single physician depends upon. The three-country trajectory recorded in this report illustrates how health systems that do not share records can each hold a partial truth about the same patient.

The authors caution, appropriately, that a single case report cannot establish the mechanism by which dengue and Leishmania interacted in this individual, only that the association coincided with atypical antigen persistence, disease progression, and treatment failure. Still, the therapeutic implication is concrete: in patients with visceral leishmaniasis who fail liposomal amphotericin B, especially those with concurrent or recent viral infections, clinicians should consider rescue therapy with miltefosine and should pursue serial virological testing to clarify what is resolving and what is not. The patient’s consent, anonymization of identifying details, ethical approval from the Nepal Health Research Council, and adherence to the Declaration of Helsinki documented in the report reflect the care taken to convert one man’s prolonged illness into a lesson for the clinics of the tropical world.

Subject of Research: Leishmania-dengue virus coinfection with persistent NS1 antigenemia complicating visceral leishmaniasis diagnosis and treatment

Article Title: Persistent dengue NS1 antigen in a patient with visceral leishmaniasis: A diagnostic and therapeutic odyssey

Article References: Chalise, B. S., Shrestha, S., Sapkota, A. S., Bajracharya, M., Basaula, Y. N., Bras‑Goncalves, R., & Manandhar, K. D. (2026). Persistent dengue NS1 antigen in a patient with visceral leishmaniasis: A diagnostic and therapeutic odyssey. BMC Infectious Diseases. https://doi.org/10.1186/s12879-026-14469-y

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14469-y

Keywords: visceral leishmaniasis, dengue virus, NS1 antigen, coinfection, miltefosine, liposomal amphotericin B, rK39 RDT, neglected tropical diseases, Nepal, migrant workers, case report, diagnostic challenges

The research team, led by Alexandra Knighton of the University of Oxford’s Medical Sciences Division together with colleagues from the Nuffield Department of Primary Healthcare Sciences, The George Institute for Global Health in New Delhi, and Emirates Health Services in Dubai, searched PubMed, CINAHL, Scopus, Overton, Google Scholar, and relevant organizational repositories for studies published between January 2015 and September 2025. The review followed the Joanna Briggs Institute methodology and PRISMA-ScR reporting standards, ensuring a transparent and reproducible evidence synthesis. Eligible studies had to report barriers to healthcare access experienced by low-wage migrant workers living in Gulf Cooperation Council countries, a population that includes the vast construction, domestic work, sanitation, and service sectors that underpin the region’s economies.

From an extensive screening process, twenty-eight documents were included in the final synthesis, collectively covering 69,988 migrant workers drawn from thirteen countries of origin. A striking feature of the evidence base is its gender skew: only about one percent of the workers represented in the included studies were female, a gap that itself signals how poorly the health experiences of women in low-wage migration are captured in the existing literature. The researchers analyzed the reported barriers thematically and then applied a system dynamics lens, exploring the two-way relationships between factors that influence access to care in order to identify leverage points where intervention could shift the whole system rather than merely treating symptoms.

The analysis identified nineteen distinct themes organized across five domains: costs, health insurance access and coverage, employment, individual factors, and systems navigation. Financial barriers loom large. Out-of-pocket costs, consultation fees, medication prices, and the fear of lost wages when taking time off work all conspire to delay care-seeking until illness becomes severe. Insurance-related barriers compound the problem, since many low-wage workers hold only minimal or employer-controlled coverage that excludes common conditions, imposes high deductibles, or lapses when employment changes. In the system dynamics framing, these factors feed back into one another: limited coverage raises effective costs, high costs discourage early treatment, delayed treatment produces more serious disease, and serious disease in turn threatens employment and income, deepening the original vulnerability.

Employment-related barriers emerged as the structural core of the system. Because most low-wage migrants in the Gulf arrive under sponsorship arrangements descended from the kafala system, their legal residency, wages, and often their ability to leave the country or change jobs depend on their employer. The review found that this dependency shapes nearly every dimension of healthcare access, from whether a worker can take time off for a clinic visit to whether a supervisor confiscates medication, whether employers report workplace injuries accurately, and whether workers fear deportation or contract termination if they disclose illness. The authors emphasize that employer dependency and kafala-like systems function as central structural determinants of care access, meaning that reforms targeting only downstream factors, such as clinic fees or language services, are unlikely to succeed without addressing the upstream power imbalance between worker and sponsor.

Individual and informational barriers add further friction. Many workers arrive with limited health literacy, speak languages that health systems in the Gulf are poorly equipped to serve, and lack familiarity with how to navigate public and private providers, referral pathways, and insurance claims. Long working hours, crowded shared accommodation, and restricted mobility make it difficult to reach facilities during opening hours. Fear of authorities, stigma around certain conditions, and uncertainty about entitlements discourage workers from asking questions or lodging complaints. These factors interact with the structural barriers: a worker whose employer withholds their passport, for example, cannot easily travel to a clinic even when care is nominally affordable, while a worker without independent channels of information may never learn that emergency care is free regardless of status.

To structure the barriers analytically, the team mapped them onto the AAAQ framework, a widely used health rights tool that assesses whether services are Available, Accessible, Acceptable, and of adequate Quality. This framing allowed the researchers to link each identified barrier to a corresponding remedial action, transforming a descriptive review into an actionable policy roadmap. The remedial actions that emerged from the evidence clustered around four actor groups: destination governments, employers, healthcare providers, and sending governments. This multi-actor architecture is one of the study’s most important contributions, because it makes explicit that responsibility for migrant health cannot be assigned to any single stakeholder in the system.

For destination governments, the evidence supports providing comprehensive and affordable health insurance coverage to low-wage migrants, strengthening and actively enforcing labor laws, and reforming sponsorship rules that tie workers to employers. For employers, remedial actions include ensuring that insurance is actually activated and understood, permitting time off for medical care, and refraining from retaliatory practices against workers who fall sick. Healthcare providers are called on to deliver active outreach to labor camps and worksites, offer multilingual information materials, and operate independent helplines and support services that workers can contact without fear of employer reprisal. Sending governments, for their part, can better prepare workers before departure by providing health-related orientation, ensuring contracts specify healthcare entitlements, and maintaining consular support channels for nationals abroad.

The authors note that despite substantial reforms across Gulf Cooperation Council countries in recent years, including widely publicized labor law changes in several states, many low-wage migrant workers continue to experience significant structural barriers to healthcare access. The system dynamics perspective helps explain why piecemeal reforms have produced uneven results: interventions at one node are dampened by counteracting pressures elsewhere in the system, such as weak enforcement, informational gaps, or employer practices that adjust to absorb new rules. Coordinated action across all four actor groups, the review concludes, offers the most credible path toward meaningful improvement, aligning the Gulf’s aspiration toward universal health coverage with the realities of a population that is, in most member states, the majority of the people living there.

The study also carries lessons well beyond the Gulf. An estimated tens of millions of low-wage migrants work across the Middle East and Asia, and similar sponsorship or employer-tied arrangements exist in other regions. By combining traditional thematic synthesis with system dynamics modeling, the researchers demonstrate a methodology that other teams can apply to map the interlocking determinants of health access for vulnerable populations anywhere. At the same time, the near-total absence of female workers from the evidence base, and the reliance on studies covering only a fraction of the migrant workforce, highlight how much remains unknown. The review’s 69,988 workers represent a substantial start, but closing the health equity gap for the Gulf’s migrant majority, the authors suggest, will require both stronger systems of care and a far richer evidence base to guide them.

Subject of Research: Barriers to healthcare access for low-wage migrant workers in Gulf Cooperation Council countries

Article Title: Improving access to care for low-wage migrant workers in the Gulf: a system dynamics informed scoping review

Article References: Improving access to care for low-wage migrant workers in the Gulf: a system dynamics informed scoping review. (n.d.). https://doi.org/10.1186/s12939-026-03002-x

Image Credits: AI Generated

DOI: 10.1186/s12939-026-03002-x

Keywords: migrant health, Gulf Cooperation Council, kafala system, healthcare access, health equity, system dynamics, scoping review, health insurance, labor migration, universal health coverage, employer dependency, migrant workers