Detection of Dengue Virus Serotype 3 in Cajamarca, Peru: Molecular Diagnosis and Clinical Characteristics

Abstract

Purpose: Dengue virus (DENV) is the most common mosquito-borne disease worldwide. This study aimed to characterize an outbreak of DENV infection in Cajamarca, Peru. Also, to identify the most common serotypes involved and describe the applicability of different diagnostic tests in the diagnosis of primary and secondary cases. Methods & Materials: The study was performed in the region of Cajamarca, in northern Peru. We included patients attending outpatient health centers with an acute febrile illness (AFI), defined as a temperature of 38°C or higher for up to 7 days, without an identifiable source of infection and presenting at least one of the following symptoms: arthralgia, myalgia, headache, retro-ocular pain, low back pain, cutaneous rash, nausea, vomiting, diarrhea, and conjunctival injection. Serum samples were collected and diagnostic tests were performed including: reverse-transcriptase polymerase chain reaction (RT-PCR), NS1 antigen, IgM and IgG antibodies ELISA-based assays. Primary infection was diagnosed by the detection of NS1 antigen ELISA and/or RT-PCR and/or IgM ELISA in the absence of IgG ELISA. Secondary infection was determined by the presence of IgG ELISA and a positive NS1 antigen ELISA and/or RT-PCR and/or IgM ELISA. Results: A total of 359 serum samples were collected in the study period. Dengue infection was diagnosed in 37.9% (136/359) of the patients, being 107 primary infections and 29 secondary infections. The most common serotype was DENV-3 in 77.5% of the cases. Differences were observed in the diagnostic performance of IgM ELISA (17.6% vs 55.2%, p≤0.01) and RT-PCR (74.8% and 31.0%, p≤0.01) in primary and secondary infections respectively. The combination of NS1 and IgM performed better than the other assays in detecting primary (91.9%) and secondary infections (96.6%). The most frequent symptoms associated with DENV infection were headaches, myalgias, and arthralgias. Conclusion: We report an important outbreak of dengue infection caused by DENV-3 in Cajamarca, Peru. Our findings encourage the use of NS1 antigen and IgM co-detection. These findings demonstrate an increasing expansion of DENV-3 in Peru and highlight the importance of molecular diagnosis and serotype characterization among febrile patients to strengthen the Peruvian epidemiological surveillance.