[ad_1]
A previously unknown outbreak of the Zika virus swept Cuba in 2017, a year after the declaration of the end of the global health emergency, scientists said Thursday.
Until now, the Pan American Health Organization had recorded no infection at Zika in Cuba in 2017, let alone an epidemic. Following New York Times investigations into the new study published in the journal Cell, officials acknowledged that they had not identified 1,384 cases reported by Cuban authorities that year.
This represents a significant increase over the 187 confirmed cases in 2016 and "corresponds to the 2017 estimates from our own study," said Kristian Andersen, an infectious disease researcher at the Scripps Research Translational Institute in La Jolla, California, a co-author of the new study.
Since most cases of Zika are unconfirmed, Dr. Andersen added, the epidemic could actually have tens of thousands of infections.
Cuba experienced record tourism in 2017, suggesting that many travelers were exposed without their knowledge. Some 4.7 million foreign visitors arrived this year, an increase of 16% over 2016. More than one million Canadians.
"If we want to stay ahead of communicable diseases, we need to know where they are and how many cases occur," said Jennifer Gardy of the Bill & Melinda Gates Foundation in Seattle. "For some diseases in some contexts, it's pretty simple. For others, like Zika, this is not the case. "
Officials of PAHO, a branch of the World Health Organization, blamed a "technical problem" for not publishing updated data on the epidemic in Cuba. By Thursday afternoon, the site had been updated.
Dr. Andersen and his colleagues began tracking the spread of Zika when the mosquito-borne virus first appeared in the Americas in 2015. The epidemic emerged in Brazil, where babies from some infected mothers were born with severe brain damage. The virus has spread rapidly in neighboring countries.
Dr. Andersen and his colleagues collected blood from people infected with the virus. The researchers took the genetic material of the virus from the samples and used DNA mutations to estimate the timing of the Zika spread.
Before Zika's identification in Brazil, scientists discovered that had been traveling quietly in the country for over a year. "And by that time, it had spread throughout the Americas," said Dr. Andersen.
Even in Florida, where the state government is closely monitoring the outbreak of new outbreaks, Zika arrived three months before its detection, the scientists learned.
In November 2016, the World Health Organization announced that the epidemic was no longer a global public health emergency. "But we were sitting here with this question," Dr. Andersen said. "Is it really over?"
[[[[Like the Science Times page on Facebook. | Sign up for the Science Times Bulletin.]
Scientists continued to follow the Zika virus across the Americas. They reviewed the data on local outbreaks reported by countries to P.A.H.O. They also identified confirmed cases of Zika among returning travelers to Florida.
Across the Americas, the two sets of statistics tell the same story: the number of Zika cases crashed in late 2016 and remained low thereafter. But there was a glaring exception in the data.
In 2016, only a few people returning to Florida from Cuba were infected with the Zika virus. In 2017, however, Cuba accounted for 98% of Zika cases associated with Florida travel.
It was an unexpected discovery. Cuba has a sophisticated public health system and seems to have won the war against Zika, apparently avoiding the epidemics observed on other Caribbean islands.
To find out if the first results were consistent, Dr. Andersen and his colleagues looked at public health data in Europe and found a similar pattern among visitors to Cuba. The team developed a statistical model to predict the size of a zika outbreak in a country, based on the number of travelers who went to Cuba and who became sick again.
They concluded that the Cuban epidemic in 2017 was "the same size as in other Caribbean islands, that is, thousands of reported cases," said Dr. Andersen. But as reported cases typically account for about 10% of a given outbreak, "we are actually talking about tens of thousands of cases."
The researchers also examined travelers' blood samples in Cuba to know the history of the epidemic and determined that the virus had appeared in Cuba in the summer of 2016. There had no Zero Patient; Instead, Zika has arrived several times other islands. Then he burned, as elsewhere, for a year.
Dr. Andersen suspects that the aggressive control of mosquitoes and surveillance of diseases in Cuba have retained the virus while raging elsewhere in 2016. Other mosquito-borne viruses, such as dengue, have also jumped in the Caribbean, but Cuba has not seen much, either.
However, after the call of the global emergency, Zika has grown in Cuba in 2017, speculated researchers.
"It's easy to miss an epidemic," said Dr. Ester Sabino, director of the Institute of Tropical Medicine at the University of São Paulo in Brazil, who did not participate in the new study. Many Zika-infected people do not experience any symptoms, while some experience only mild fever for a few days.
It is rare in many Latin American countries that an infection is confirmed by a sophisticated genetic test, Dr. Sabino said. The methods used by Dr. Andersen's team were "a smart way to monitor the world" for diseases like Zika, she added.
Dr. Andersen said the new study adds to the evidence that public health officials need to look for signs of the epidemic sooner.
"In many of these cases, we expect to see strange symptoms and illness in patients, and then we realize we have an epidemic," he said. "If we examine mosquitoes, we could detect it much sooner."
[ad_2]
Source link