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更新时间:2016-2-20 8:39:16 来源:纽约时报中文网 作者:佚名

Zika May Increase Risk of Mental Illness, Researchers Say

A baby with a shrunken, misshapen head is surely a heartbreaking sight. But reproductive health experts are warning that microcephaly may be only the most obvious consequence of the spread of the Zika virus.


Even infants who appear normal at birth may be at higher risk for mental illnesses later in life if their mothers were infected during pregnancy, many researchers fear.


The Zika virus, they say, closely resembles some infectious agents that have been linked to the development of autism, bipolar disorder and schizophrenia.


Schizophrenia and other debilitating mental illnesses have no single cause, experts emphasized in interviews. The conditions are thought to arise from a combination of factors, including genetic predisposition and traumas later in life, such as sexual or physical abuse, abandonment or heavy drug use.


But illnesses in utero, including viral infections, are thought to be a trigger.


“The consequences of this go way beyond microcephaly,” said Dr. W. Ian Lipkin, who directs The Center for Infection and Immunity at Columbia University.

“它的后果远远超出了小头畸形,”哥伦比亚大学感染与免疫研究中心主任W·伊恩·李普金(W. Ian Lipkin)说。

Among children in Latin America and the Caribbean, “I wouldn’t be surprised if we saw a big upswing in A.D.H.D., autism, epilepsy and schizophrenia,” he added. “We’re looking at a large group of individuals who may not be able to function in the world.”


Researchers in Brazil are investigating thousands of reports of microcephalic births. While there is no solid proof that Zika virus is the cause, virologists studying the outbreak strongly suspect it.


Although the virus was discovered in 1947, there has been no research into its long-term consequences. Scientists are left to draw inferences from what is known of similar infections.


In interviews, psychiatric researchers specializing in fetal development agreed with Dr. Lipkin’s pessimistic prognosis.


A viral attack early in pregnancy can kill a fetus or stunt the growing brain, producing microcephaly, they explained. An infection later in the fetus’s development, when the brain is nearly fully formed, can do damage that is less obvious but still significant.


“It is pretty scary,” said Dr. Urs Meyer, a behavioral neurobiologist at the Swiss Federal Institute of Technology in Zurich who studies the consequences of fetal infections in lab animals. “These problems are on a continuous scale, and whether you end up with autism or schizophrenia is complex — and we really can’t predict it.”

“挺吓人的,”瑞士苏黎世联邦工学院(Swiss Federal Institute of Technology in Zurich)行为神经生物学家于尔·梅耶(Urs Meyer)说。“这些问题在一个连续的量表上,你最终是不是会患上自闭症或精神分裂症是很复杂的问题——我们实际上也并不能预测。”梅耶研究的是实验室动物胚胎感染的后果。

Evidence has increased for years that mental illnesses may be linked to exposure during pregnancy to viruses like rubella, herpes and influenza, and to parasites like Toxoplasma gondii.


The effects of Zika mimic those of rubella, some experts noted: Both cause only a mild rash in adults, but can cause stillbirths, microcephaly and eye malformations in newborns.


In the 1964-65 rubella epidemic, about 20,000 newborns suffered consequences, including 11,000 born deaf, 3,500 born blind — and at least 1,800 in whom mental problems were later diagnosed.


That epidemic infected an estimated 12 million Americans. More than 500 million people live in the countries of Latin America and the Caribbean to which the World Health Organization has predicted that Zika will spread.


Pathologists in Ljubljana, Slovenia, who dissected a microcephalic fetus aborted at 32 weeks by a European woman who had become pregnant in Brazil reported last week that they found “severe fetal brain injury associated with ZIKV infection with vertical transmission” — meaning the Zika virus had come from the mother’s infection.


But a pathogen may not even have to reach the fetus to cause damage.


Flu viruses do not cross the placenta, Dr. Meyer of the Swiss Institute noted, but the mother’s immune reaction creates a storm of cytokines, some of which do. Cytokines are small “signaling” proteins that can cause cells to stop growing.


Reports suggest that Brazil, which was facing economic crises even before the Zika outbreak, has little capacity to cope with a surge of mentally disabled children.


European researchers initially paid little attention to the South American outbreak, Dr. Meyer said. But that has changed.


“The information we’re hearing now is just overwhelming,” he said. “A whole generation of children might be affected.”