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Zika Virus: Spread and Complications

2016-02-09

In my previous post about Zika virus, I noted that it had spread from Africa and Asia, across the Pacific Ocean, with stops in Yap and Easter Island, and into South America.  A recent article in the New York Times discussed the spread of Zika into Brazil and its appearance as an epidemic after the 2014 soccer World Cup: a definite identification was made by May 14, 2015.  Early in 2015, in Brazil, patients began to appear in large numbers with fever, rash, joint pain, and headaches.  Most patients had mild disease, but complications showed up soon: Guillan-Barre syndrome, a rare neurological syndrome.

By March of 2015, cases had spread to Salvador, a city of 2.5 million; by April, the cause of the “mystery disease” had been identified: Zika virus.  Ironically, Zika had already been identified in the US in travelers from the Pacific.

The first identification of Zika virus in the US came from an international traveler who had just returned from a tour of the western Pacific in December 2013.  He walked in to the Traveler’s Medical Service on Madison Avenue in New York City with a rash that, he said, had persisted for eleven days.  The nurse practicioner who first saw him thought he had dengue fever, but the symptoms were not nearly severe enough.  The traveler, an intelligent, sophisticated man, told the NP that he knew he had Zika virus.  He had been reading reports in the newspapers in Polynesia about the virus and its sudden appearance in the islands.

The patient had also read an article about a scientist in Colorado who had infected his wife with Zika after returning from Africa.  Because of this, he avoided having unprotected sex with his partner and kept her from being infected.  The CDC later issued a warning about transmission of Zika virus through unprotected intercourse.

He had even heard about cases of Guillan-Barre syndrome.  This condition is a form of temporary paralysis that starts distally, in the hands and feet.  The syndrome is usually resolved after several weeks, but it can be deadly if it reaches the muscles that power breathing; immediate placement on a ventilator if a patient develops distress is required to assist respiration.  It is thought to be caused by an autoimmune attack on the nerves that supply voluntary muscles, a side effect of the body’s immune response to the viral attack.

Back in Brazil, numerous cases of Guillan-Barre syndrome began to appear.  Then, in July 2015, a pair of twins, one of them afflicted with microcephaly (a small head), were born in Recife.  In August, the parents brought the infants to a famous neurologist, Dr. Vanessa van der Linden; she ruled out the usual causes of microcephaly: syphilis, toxoplasmosis, rubella, and other congenital infections, as well as genetic causes like Down’s syndrome.  By September, the public hospital in Recife had five cases of microcephaly.  Dr. van Linden’s mother, a pediatric neurologist, soon had seven cases of microcephaly at the hospital where she worked.

Recife is in northern Brazil, and Natal, capital of the state of Rio Grande do Norte, is about 200 miles up the coast from Recife.  Natal was one of the host cities of the World Cup soccer championship.

The infants tested negative for Zika virus, but many of their mothers recalled having had an illness with a rash months earlier, during their first trimester of pregnancy.  Most of these women were from rural areas, and had minimal to no education.  “Dr. Kátia Petribu, a hospital psychiatrist in Recife” described the overwhelming experience of the mothers: they came by bus from far away, with nothing but the clothes on their backs and their peculiar children.  ‘ “They come with nothing,” she said. “No food. They travel by bus for hours, arrive at 7 a.m., and wait for hours to be seen.” ‘

In severe cases, these infants appeared to have no foreheads: their faces simply terminated at the eyebrows.  The mothers, with no knowledge of medicine, had forlorn hopes that their children would somehow grow out of it.  Many of them were in shock at the appearance of their monstrous children.  The infants still behaved as if they were normal: they nursed normally, slept, woke up, cried, and were comforted.

The criterion for microcephaly had been a head size of 33 cm at birth; to narrow the definition, scientists changed the measure down to 32 cm.

Dr. Mauricio L. Nogueira, from the southern part of Brazil where no cases had been seen, visited a hospital in the north and was stunned by what he saw: 25 infants born in a single ten day period with microcephaly.  The NYT says: “He is still haunted by what he saw.”  ‘ One mother, he said, looked up at him and asked, “Hey, doctor, his head is going to grow, right?” ‘

The World Health Organization (WHO) declared a public health emergency on February 1, 2016 because of a spike in cases of Guillan-Barre syndrome and microcephaly in the Americas.  WHO has a Q+A page with general information about the virus and additional materials on line.  WHO has also coordinated activities of scientists around the world and is working on controlling the Aedes mosquito which carries Zika.  The same control measures used for malaria would be effective against Zika.

In November 2015, scientists obtained amniotic fluid (the fluid that surrounds the growing fetus) and found Zika virus.  Two stillbirths were analyzed and, again, Zika virus was found in their brain tissue.  This represents the first time a mosquito-borne virus has been directly associated with congenital malformations.

At last, the epidemic appears to have peaked: in Recife, the incidence of microcephaly in newborns appears to have declined during the last three weeks.  This was the first spot that the infection was recognized in South America, and there are some 600 million people on the continent who have never been exposed before.  Thousands of cases of microcephaly have been reported in Brazil and Colombia, most thought to be linked to the Zika virus.

North America has never been exposed to the virus, and epidemiologists think there will be at least small outbreaks here.  There are areas of the southern United States where mosquitoes breed year-around, and these are likely to have some degree of spread of the virus.  Aggressive mosquito-control measures are warranted and have already begun in Florida, Texas, and across the South.

 

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