RECIFE (Brazil) • So many distraught mothers stream into the infant ward clutching babies with abnormally small heads that the receptionist sends them outside the hospital, to see if they can find a chair to wait under the mango tree.
"There's shade there, at least," Ms Maria Helena Lopes, 66, told them. "We'll call you when we're ready."
Ms Roziline Ferreira took three buses to get to this hospital in Recife, grasping her three-month-old son all the way. Tears swelled as she looked at him, recalling how the symptoms of the Zika virus had struck her during the second month of her pregnancy.
"It gets me angry when someone on the bus looks at Arthur and asks, 'What's wrong with his head?' " she said. "I tell them, 'Nothing's wrong, he's just different.' But then I think to myself, 'Yes, something's wrong. My son will never be like the other boys'."
This poverty-stricken city in Brazil is at the centre of a nightmarish health crisis that has set off alarms across the Western Hemisphere.
Mothers began showing up at the Oswaldo Cruz Hospital with their affected babies as early as last September, stunning doctors and leaving even the most experienced among them scrambling to figure out what was going on.
"We've had our share of epidemics, but this is unprecedented," said the head of the infant care unit, Dr Angela Rocha, who began working at the hospital in 1973.
Before last autumn, medical reports of babies born with brain damage and unusually small heads - a condition known as microcephaly - were so uncommon that only about 150 cases were registered each year in Brazil. Now officials are investigating thousands of them, and they contend that the Zika virus is the cause.
Virus specialists are racing to understand the connection, if any, between Zika and the rash of microcephaly cases in Brazil, an undertaking that international officials warn could take six months or more.
But whatever the cause, there is "no doubt that Brazil is experiencing a significant increase in microcephaly", said a Health Ministry official who asked not to be named. "We wouldn't have declared this situation a health emergency if this increase had not been detected."
Researchers here believe the virus made the leap from Polynesia to Brazil during the 2014 World Cup soccer tournament. Since then, as many as 1.5 million people in Brazil are believed to have been infected.
The most common symptoms are relatively mild, like fever and joint pain, and most people with the virus feel no ill effects.
As Zika spread across Brazil, particularly here in the north-east, doctors began seeing a stream of babies with unusually small heads.
"I saw this dramatic increase in cases with my own eyes," said Dr Vanessa Van Der Linden, a neurologist who was among the first doctors to detect an increase in microcephaly cases last year. Altogether, she has examined about 60 cases in the past six months, she said - 10 times the rate of cases she came across in previous years.
Many of the mothers, already overwhelmed by poverty, are now grappling with an incurable condition in their babies that can involve seizures, impaired cognitive development, delayed motor functions, speech problems and dwarfism.
The full extent of the crisis is still far from clear as reporting microcephaly became mandatory across the country only in the past few months. Officials last week said reported cases have reached 4,180 since October, a 7 per cent increase from the tally in the previous week.
Faced with so many cases, doctors in Recife say Brazil needs to intensify its battle against the virus on many fronts, from expanding mosquito eradication campaigns to developing a vaccine.
"It's fine and it's necessary to have an academic discussion about the statistics, but we're here on the ground dealing with the increase in microcephaly cases," Dr Van Der Linden said.
NEW YORK TIMES