Epidemiological profile of Zika, Dengue and Chikungunya virus infections identified by medical and molecular evaluations in Rondonia, Brazil

Abstract

Several arboviruses have emerged and/or re-emerged in North, Central and South-American countries. Viruses from some regions of Africa and Asia, such as the Zika and Chikungunya virus have been introduced in new continents causing major public health problems. The aim of this study was to investigate the presence of RNA from Zika, Dengue and Chikungunya viruses in symptomatic patients from Rondonia, where the epidemiological profile is still little known, by one-step real-time RT-PCR. The main clinical signs and symtoms were fever (51.2%), headache (78%), chills (6.1%), pruritus (12.2%), exanthema (20.1%), arthralgia (35.3%), myalgia (26.8%) and retro-orbital pain (19.5%). Serum from 164 symptomatic patients were collected and tested for RNA of Zika, Dengue types 1 to 4 and Chikungunya viruses, in addition to antibodies against Dengue NS1 antigen. Direct microscopy for Malaria was also performed. Only ZIKV RNA was detected in 4.3% of the patients, and in the remaining 95.7% of the patients RNA for Zika, Dengue and Chikungunya viruses were not detected. This finding is intriguing as the region has been endemic for Dengue for a long time and more recently for Chikungunya virus as well. The results indicated that medical and molecular parameters obtained were suitable to describe the first report of symptomatic Zika infections in this region. Furthermore, the low rate of detection, compared to clinical signs and symptoms as the solely diagnosis criteria, suggests that molecular assays for detection of viruses or other pathogens that cause similar symptoms should be used and the corresponding diseases could be included in the compulsory notification list.

Figure 1. Amplification profile depicting the threshold cycles (Cts) of positive patients and negative ones: A) Red line: positive ZIKV patient; B) Blue line: a negative patient to ZIKV, showing only the amplification of the internal control.

Figure 2. Amplification profiles depicting the Cts (on the abscissa axis) of positive samples for ZIKV, CHIKV, and DENV and the controls supplied by the Kit Biomol ZDC: A) Zika; B) Chikungunya; C) Dengue 1 and Dengue 4; D) Dengue 2 and Dengue 3. The amplification profiles of the studied viruses are represented in red or turquoise, while the controls are always represented in blue. The emitted fluorescence threshold (on the ordinate axis) for Zika is 0.5; for Dengue 1 and the Control is 0.2; for Dengue 2 is 0.5 and for Dengue 3 and 4 is 0.4 and for Chikungunya is 1.