Feb. 26--A killer is on the loose in the Americas, blamed for dozens of deaths and thousands of critical injuries. Officials have identified a prime suspect that appears to have the means, motive and mosquitoes to carry out its attacks.
The Zika virus has been indicted in Brazil and elsewhere for a mysterious spike in cases of microcephaly, a rare birth defect that can have devastating consequences. The circumstantial evidence is so compelling that Dr. Margaret Chan, head of the World Health Organization, called Zika a threat of "alarming proportions."
Physicians are on heightened alert, pregnant women are in fear and public health officials are scrambling to contain the virus, which until recently had been considered more of a nuisance than a menace.
But if this were a murder investigation, prosecutors would still have a long way to go to prove that Zika is indeed guilty as charged.
"It's entirely possible there's something else going on in Brazil -- something unique to the population or environment in which transmission takes place," said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases in Bethesda, Md.
There's certainly good reason to put Zika on the most wanted list: Its fingerprints are at the scene of the crime. The virus was found inside the severely underdeveloped brain of a 29-week-old aborted fetus, according to a report this month in the New England Journal of Medicine. A subsequent study in the medical journal Lancet identified Zika in the amniotic fluid of infected pregnant women carrying microcephalic fetuses.
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However, some babies born with microcephaly have no apparent link to Zika, and many women who believe they were infected during pregnancy have given birth to healthy babies.
Nailing down Zika's precise role -- if any -- in these and other neurological disorders will require hard work by investigators from a wide range of scientific and medical disciplines.
"We're pretty clear that Zika is causing this," said Dr. Albert Ko, an infectious disease physician and epidemiologist at Yale University who is helping Brazilian health authorities investigate the outbreak. "But we need to firm those suspicions up."
