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Zika outbreak in Mexico traced to A. aegypti mosquito
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A Zika virus outbreak that occurred in Mexico during late 2015 has been traced back to the Aedes aegypti mosquito, researchers reported, marking the first confirmed Zika transmission by that species to occur in North America.
“These results demonstrate the continued, rapid northward progression of [Zika virus] into North America with typically mild disease manifestations, and implicate A. aegypti for the first time as a principal vector in North America,” Mathilde Guerbois, PhD, of the University of Texas Medical Branch, Galveston, and colleagues wrote.
In late November and early December 2015, researchers detected an outbreak of Zika virus in southern Mexico, with patients near Tapachula, Chiapas State, exhibiting rash, fever and conjunctivitis. Of 119 suspected Zika cases, 25 (21%) were confirmed by serum testing. Sera were collected between 1 and 10 days after symptom onset. Of the 25 confirmed cases, 15 were female (60%), with an average patient age of 33.1 years.
Researchers then collected 796 mosquitos from the patients’ homes and sorted them into 55 pools by species, sex, location and date of collection. The majority of mosquitos were A. aegypti (59.3%). Of the 55 pools, 15 (27.3%) contained Zika virus, Guerbois and colleagues reported.
Although a lack of evidence implicating A. aegypti had previously led to suspicions that Culex quinquefasciatus could be a vector, Guerbois and colleagues wrote, Zika was not detected in any samples of that species.
“Our implication of A. aegypti in [Zika virus] transmission in southern Mexico is important because no natural mosquito infections are reported in the peer-reviewed literature since Zika virus reached the Americas, and some experimental studies suggest that this species develops disseminated infections at a low frequency even after high titer bloodmeals,” Guerbois and colleagues wrote. “However, based on its nearly ideal anthrophilic behavior, this species can transmit human viruses to epidemic proportions even when it is relatively insusceptible. Our first conclusive implication of this species in [Zika virus] transmission in the Americas, based on the detection of virus identical or nearly so to strains from humans living in the same households, supports the need for additional efforts to control A. aegypti as one of the few interventions currently available for the ongoing outbreak.” – by Andy Polhamus
Disclosures: The researchers report no relevant financial disclosures.
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