Revised: June 9, 2026
Accepted: June 29, 2026
Published online: September 25, 2026
Processing time: 166 Days and 22.9 Hours
Sand fly fever virus (SFFV) infection is an acute self-limiting febrile illness caused by phleboviruses and transmitted by sand flies of the Phlebotomus species. The disease has been reported in the Mediterranean region, North Africa, the Middle East, and the Indian subcontinent, and is now considered to be expanding into new geographic areas. Clinically, SFFV infection closely resembles acute dengue fever.
To detect other possible infection including SSFV in patients with clinically su
In this study, a total of 757 serum samples were collected from patients clinically suspected of dengue fever and admitted to three major hospitals in Sri Lanka between January and August 2023. Patients were from the Colombo and Kandy District, and demographic information was obtained from laboratory request forms, although detailed individual-level demographic data were limited due to anonymization in this laboratory-based study. All samples were initially screened for dengue NS1 antigen negativity and further tested for a panel of pathogens including SFFV immunoglobulin (Ig) M, hantavirus IgM, chikungunya IgM, and leptospira IgM antibodies, as well as molecular detection of hantavirus, flavivirus, and alphavirus RNA.
From tested samples, two samples were serologically positive for SFFV-specific IgM using a commercial im
This study provides the first evidence of SFFV infection in Sri Lanka. Given the high endemicity of dengue in the country, SFFV infections may be clinically misdiagnosed as dengue and therefore remain under-recognized. Further studies involving febrile patients and sand fly vector surveillance are required to determine the true burden and epidemiological significance of SFFV in Sri Lanka.
Core Tip: Sand fly fever virus (SFFV) infection is an acute self-limiting febrile illness caused by Phleboviruses and transmitted by sand flies of the Phlebotomus species. Clinically, SFFV infection closely resembles acute dengue fever and specific laboratory tests are required to diagnose SSFV. In Sri Lanka, a certain proportion of clinically suspected dengue patients were negative for dengue by laboratory investigation. We conducted this study to detect other possible pathogens in a group of patients admitted to hospitals with clinically dengue like illness. Seven hundred and fifty-seven patients’ samples were tested and two samples were positive for immunoglobulin M antibodies against SFFV, indicating recent or acute infection. The clinical and laboratory features of these patients were similar to those of uncomplicated dengue fever. Both patients were tested negative for flavivirus, alphaviruses, hantaviruses and leptospirosis. This study provides the first evidence of SFFV infection in Sri Lanka. As dengue fever is highly endemic in the country, SFFV infections may often be misdiagnosed as dengue and remain undetected. Further studies on febrile patients and sand fly vectors are needed to determine the disease burden and support effective control measures.