Unexpected arboviruses found in an epidemiological surveillance of acute tropical febrile syndrome in the department of Meta, Eastern Colombia.

BACKGROUND: Nonspecific acute tropical febrile illnesses (NEATFI) are common in the Latin American tropics. Dengue, Chikungunya, Zika, Mayaro, and Usutu, among others, can coexist in the American tropics. This study aimed to surveil the arboviruses that cause| acute febrile syndrome in patients in the Meta department, Colombia. METHODS: Between June 2021 and February 2023, an epidemiological surveillance study was conducted in the Llanos of the Meta department in Eastern Colombia. RESULTS: One hundred patients in the acute phase with typical prodromal symptoms of NEATFI infection who attended the emergency department of the Villavicencio Departmental Hospital were included. ELISA tests were performed for Dengue, Usutu, Chikungunya, and Mayaro. RT-qPCR was performed to detect the arboviruses Usutu, Dengue, Zika, Mayaro, and Oropouche. The seroprevalence for the Chikungunya, Mayaro, and Usutu viruses was 41 % (28/68), 40 % (27/67), and 62 % (47/75), respectively. Seroconversion for Chikungunya was observed in one patient; two seroconverted to Mayaro and one to Usutu. The NS5 gene fragment of the Usutu virus was detected in nine febrile patients. RT-qPCR of the remaining arboviruses was negative. The clinical symptoms of the nine Usutu-positive patients were very similar to those of Dengue, Chikungunya, Zika, and Mayaro infections. CONCLUSIONS: The pervasive detection of unexpected viruses such as Usutu and Mayaro demonstrated the importance of searching for other viruses different from Dengue. Because Usutu infection and Mayaro fever have clinical features like Dengue, a new algorithm should be proposed to improve the accuracy of acute tropical fevers.

Outbreak of Chikungunya virus in the north Caribbean area of Colombia: clinical presentation and phylogenetic analysis.

INTRODUCTION: The Caribbean area of Colombia has been severely affected by a Chikungunya virus (CHIKV) outbreak since 2014. METHODOLOGY: The study was carried out on 100 patients during a fever outbreak from August to September 2014 in two small rural villages in the northern Caribbean area of Colombia. The molecular assays performed by reverse transcription polymerase chain reaction (RT-PCR) on acute patient sera were collected within one to five days of the appearance of symptoms. Sequence analyses were carried out based on phylogenetic analyses of genes NS1 and E2. For serological assays, 49 (49%) patients at ≥ 6 days of disease onset were tested with NovaLisa Chikungunya IgG/IgM µ-capture enzyme-linked immunosorbent assay (ELISA). RESULTS: The main signs or symptoms associated with Chikungunya infection were arthralgia of the lower limbs (96%), fever (91%), arthralgia of the upper limbs (85%), rash (64%), and headache (57%). Ninety-four percent (46/49) of patients were positive for either IgM or IgG; the remaining three (6%) patients were seronegative. Viral loads were detected in 25 patients. Based on phylogenetic analysis of NS1 and E2, the characterization of the Colombian CHIKV indicated that it was a strain closely related to the British Virgin Islands strain and to the Asian genotype. CONCLUSIONS: This study shows the phylogenetic and clinical description of CHIKV in Colombia. The main symptoms shown were: arthralgia, fever, and rash. CHIKV sequences detected in Colombian patients were within the Asian genotype and closely related to the British Virgin Islands strain.