PAHO says Zika virus likely to march through Americas
Lisa Schnirring
CIDRAP News
Jan 25, 2016
Zika virus will probably spread in all countries and territories in the Americas where Aedes mosquitoes are found, and one more country—the Dominican Republic—has reported local transmission, according to new updates from the Pan American Health Organization (PAHO).
Chile and Canada are the only countries in the Americas where Aedes mosquitoes, the main vector for Zika virus transmission, are not found.
PAHO also weighed in on why the disease is spreading so quickly: because people in the Americas have not been exposed to Zika virus before, leaving populations without immunity, and because Aedes mosquitoes are widespread in the region. The same type of mosquito is also linked to two other diseases in the region, dengue and chikungunya.
Transmission knowledge gaps
Other transmission routes pose some risks, but so far the evidence is limited, PAHO said. Zika virus has been isolated in semen, and one instance of possible human-to-human sexual transmission has been reported. However, more data are needed to confirm a link, the agency said.
Zika virus can be transmitted through blood, but it occurs infrequently, according to PAHO, which urged health providers to observe standard precautions that are already in place for blood donations and transfusions. Evidence of mother-to-child transmission during pregnancy or childbirth is also limited, but research is under way to better understand perinatal transmission and how the virus affects babies.
Brazil, where the virus has struck earliest and hardest in the Americas, has reported a large increase in microcephaly cases, which involve small heads and brains in newborns. And scientists have isolated the virus in amniotic fluid, blood, and tissue samples from Brazilian newborns, as well as in placental tissue. Risk assessments from health organizations, however, emphasize that it’s hard to gauge the true magnitude of the problem.
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