Abstract
BackgroundWith the arrival of chikungunya (CHIKV) and zika (ZIKV) viruses in Mexico, there was a decrease in diagnosed dengue virus (DENV) cases. During the first years of cocirculation (2015–2017), the algorithms established by epidemiological surveillance systems and the installed capacity limited us to one diagnostic test per sample, so there was an underestimation of cases until September 2017, when a multiplex algorithm was implemented. Therefore, the objective of this study was determine the impact of the introduction of CHIKV and ZIKV on the incidence of diagnosed DENV in endemic areas of Mexico, when performing the rediagnosis, using the multiplex algorithm, in samples from the first three years of co-circulation of these arboviruses.Methodology and principal findingsFor this, 1038 samples received by the Central Laboratory of Epidemiology between 2015 and 2017 were selected for this work. Viruses were identified by multiplex RT-qPCR, and the χ2 test was used to compare categorical variables. With the new multiplex algorithm, we identified 2.4 times the rate of arbovirosis as originally reported, evidencing an underestimation of the incidence of the three viruses. Even so, significantly less dengue was observed than in previous years. The high incidence rates of chikungunya and Zika coincided with periods of dengue decline. The endemic channel showed that the cases caused by DENV rose again after the circulation of CHIKV and ZIKV decreased. In addition, 23 cases of coinfection were identified, with combinations between all viruses.Conclusions and significanceThe results obtained in this study show for the first time the real impact on the detected incidence of dengue after the introduction of CHIKV and ZIKV in Mexico, the degree of underestimation of these arboviruses in the country, as well as the co-infections between these viruses, whose importance clinical and epidemiological are still unknown.
Highlights
Arboviruses are a heterogeneous group of viruses that, as a common characteristic, require the participation of arthropod vectors for their transmission between hosts [1]
The results obtained in this study show for the first time the real impact on the detected incidence of dengue after the introduction of chikungunya virus (CHIKV) and zika virus (ZIKV) in Mexico, the degree of underestimation of these arboviruses in the country, as well as the co-infections between these viruses, whose importance clinical and epidemiological are still unknown
It is possible that the decrease in the number of reported cases of dengue is related to the similarity of the clinical picture of these infections, since the symptoms are very similar and, during years of CHIKV and ZIKV introduction, an independent diagnostic algorithm was used for each virus [6,7,8]; that is, the physician had to request the confirmatory diagnostic test for the initial clinical suspicion based on symptoms, and in the case of a negative result, no other test was performed for a differential diagnosis
Summary
Arboviruses (for arthropod-borne viruses) are a heterogeneous group of viruses that, as a common characteristic, require the participation of arthropod vectors for their transmission between hosts [1]. Among the most important arboviruses in recent years are dengue virus (DENV), chikungunya virus (CHIKV), and zika virus (ZIKV) [2]. In the fourth quarter of 2017, all these techniques in uniplex format were replaced by one in multiplex format, which detects DENV, CHIKV, and ZIKV simultaneously [9]. With the arrival of chikungunya (CHIKV) and zika (ZIKV) viruses in Mexico, there was a decrease in diagnosed dengue virus (DENV) cases. The objective of this study was determine the impact of the introduction of CHIKV and ZIKV on the incidence of diagnosed DENV in endemic areas of Mexico, when performing the rediagnosis, using the multiplex algorithm, in samples from the first three years of co-circulation of these arboviruses
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