Abstract
Background: This study investigates the epidemiology of dengue (DENV) and chikungunya (CHIKV) viruses in Mansehra district, Khyber Pakhtunkhwa, Pakistan, a region where both Aedes-borne diseases have become common in the recent times.
Methods: We conducted a retrospective observational analysis of human case data (2013–2024) and entomological surveys to measure co-circulation patterns. Hospital and national laboratory epidemiological records were reviewed to describe the outbreak periods, patient demographics and clinical aspects. At the same time, Aedes larval surveillance (house, container, and Breteau index) was conducted in the Union Councils that were affected. We also compared our results with the published reports of arbovirus outbreak in Pakistan (Table 1).
Results: Major findings indicated that dengue is still an endemic disease in the area whereby the annual outbreaks are highest after the monsoon. High national dengue burden was recorded in Punjab and Khyber Pakhtunkhwa (KPK) in the year 2021[1]. It is worth mentioning that 20132015 surveillance in KPK detected all four DENV serotypes co-circulating (mainly DENV3)[2] and in 2015 Mansehra contributed nearly three-quarters of provincial dengue incidence[3]. Chikungunya was mostly unfamiliar until recently: a nation-wide outbreak of CHIKV in 2016-17 (2,582 cases in 2016) was verified as ECSA genotype[4], with majority of cases in Sindh (84.7%)[5]. In September 2024, a smaller CHIKV outbreak (14 cases confirmed) took place in Mansehra[6]. Every patient with CHIKV was reported to have had fever and severe arthralgia [6].
Conclusion: We found that there is overlapping DENV and CHIKV transmission cycles using the same vectors of Aedes, and there is similarity in clinical manifestation of these two diseases, and this makes them difficult to diagnose. Combined surveillance and control of the vectors are imperative. This research gives specific data on the outbreak and indicates the necessity to conduct joint disease surveillance in the common areas of risks.