ABSTRACT
Since 2015, the Dengue, Zika, and Chikungunya viruses gained notoriety for their impact in public health in many parts of the globe, including Brazil. In Recife, the capital of Pernambuco State, the introduction of ZIKV impacted human population tremendously, owing to the increase in the number of neurological cases, such as the Guillain−Barré and congenital Zika disorders. Later, Recife was considered to be the epicenter for ZIKV epidemics in Brazil. For arboviral diseases, there are some risk factors, such as climate changes, low socioeconomic conditions, and the high densities of vectors populations, that favor the broad and rapid dispersion of these three viruses in the city. Therefore, continuous arbovirus surveillance provides an important tool for detecting these arboviruses and predicting new outbreaks. The purpose of the present study was to evaluate the circulation of DENV, ZIKV, and CHIKV by RT-qPCR in mosquitoes collected in health care units from the metropolitan area of Recife (MAR), during 2018. A total of 2321 female mosquitoes (357 pools) belonging to two species, Aedes aegypti and Culex quinquefasciatus, were collected from 18 different healthcare units, distributed in five cities from the MAR. Twenty-three pools were positive for ZIKV, out of which, seventeen were of C. quinquefasciatus and six were of A. aegypti. Positive pools were collected in 11/18 health care units screened, with Cq values ranging from 30.0 to 37.4 and viral loads varying from 1.88 × 107 to 2.14 × 109 RNA copies/mL. Nosocomial Aedes- and Culex-borne transmission of arbovirus are widely ignored by surveillance and vector control programs, even though healthcare-associated infections (HAI) are considered a serious threat to patient safety worldwide. Although the results presented here concern only the epidemiological scenario from 2018 in MAR, the potential of hospital-acquired transmission through mosquito bites is being overlooked by public health authorities. It is, therefore, of the ultimate importance to establish specific control programs for these locations.
ABSTRACT
Resistance to chemical insecticides detected in Aedes aegypti (L.) mosquitoes has been a problem for the National Dengue Control Program (PNCD) over the last years. In order to provide deeper knowledge of resistance to xenobiotics, our study evaluated the susceptibility profile of temephos, diflubenzuron, and cypermethrin insecticides in natural mosquito populations from the Pernambuco State, associating these results with the local historical use of such compounds. Furthermore, mechanisms that may be associated with this particular type of resistance were characterized. Bioassays with multiple temephos and diflubenzuron concentrations were performed to detect and quantify resistance. For cypermethrin, diagnostic dose assays were performed. Biochemical tests were carried out to quantify the activity of detoxification enzymes. In addition, a screening of mutations present in the voltage-gated sodium channel gene (NaV) was performed in samples previously submitted to bioassays with cypermethrin. The populations under study were resistant to temephos and showed a positive correlation between insecticide consumption and the resistance ratio (RR) to the compound. For diflubenzuron, the biological activity ratio (BAR) ranged from 1.3 to 4.7 times, when compared to the susceptible strain. All populations showed resistance to cypermethrin. Altered enzymatic profiles of alpha, p-nitrophenyl acetate (PNPA) esterases and glutathione-S-transferases were recorded in most of these samples. Molecular analysis demonstrated that Arcoverde was the only population that presented the mutated form 1016Ile/Ile. These findings show that the situation is critical vis-à-vis the effectiveness of mosquito control using chemical insecticides, since resistance to temephos and cypermethrin is widespread in Ae. aegypti from Pernambuco.
