Zika virus is an arbovirus in the family of Flaviviridae; and is transmitting through the bites of mosquito vectors (usually of Aedes aegypti mosquitoes). The outbreaks study reporting that Zika virus infection in pregnant women is also to be associating with; among other medical complications; microcephaly in their infants and sometimes even fetal deaths.
But the research study showing that Brazil cases reporting positive results for ZIKV by RT-PCR in samples taking from the States of Rio Grande and Bahia. This was the first report of locally-acquired Zika virus infection in Brazil. The first wave of ZIKV hit northeastern Brazil in the first quarter of 2015 and starting fading out since September; and was severely underreporting since the mandatory ZIKV case notification only started in February 2016.
Outbreaks of Zika virus
The three parameters reflect the levels of infectivity, severity and the inflection time point of an epidemic, respectively. Knowledge of these epidemiological parameters summarize the temporal pattern of an epidemic and is helpful to understand the features of an outbreak.
The study showing that three simple growth models can be adapted to model the ZIKV outbreak, with the best R2 reaching 0.995. The estimated dates of the turning points varied from January to April of 2016 for the eight states. The difference in the turning points indicates spatial heterogeneity in the timing of the outbreak. The local conditions, e.g. demographic factors, public health policies; seasonality including meteorological factors and other factors affecting mosquito activities, probably varied in different states.
Positive ZIKV cases
Hence, the growth structure of the epidemic curve could be affecting; and thus the turning points are likely to appear heterogeneously across states. To further evaluate the timely efficiency of the local ZIKV notification, we checked if the turning point appeared in the latter half of the whole reporting period.
Therefore, to avoid excluding the part of positive ZIKV cases in the suspected group; study considering the summation of suspected and confirmed cases as the incidence count for analysis. If the reporting delays, dates of onset, or the reporting rate are known, more realistic and comprehensive analysis can be performed that includes more accurate epidemic data and information.