Zika Virus Update
“Though our study is small, it may provide evidence that in this case the virus has different effects on the brain than those identified in current studies,” said study author Maria Lucia Brito Ferreira, MD, with Restoration Hospital in Recife, Brazil. “Much more research will need to be done to explore whether there is a causal link between Zika and these brain problems.”
For the study, researchers followed people who came to the hospital in Recife from December 2014 to June 2015 with symptoms compatible with arboviruses, the family of viruses that includes Zika, dengue and chikungunya. Six people then developed neurologic symptoms that were consistent with autoimmune disorders and underwent exams and blood tests. The authors saw 151 cases with neurological manifestations during a period of December 2014 to December 2015.
All of the people came to the hospital with fever followed by a rash. Some also had severe itching, muscle and joint pain and red eyes. The neurologic symptoms started right away for some people and up to 15 days later for others.
Of the six people who had neurologic problems, two of the people developed acute disseminated encephalomyelitis (ADEM), a brief but severe attack of swelling of the brain and spinal cord. ADEM also attacks the nerves of the central nervous system and damages their myelin insulation, which, as a result, destroys the white matter. In both cases, brain scans showed signs of damage to the brain’s white matter. Unlike multiple sclerosis (MS), ADEM usually consists of a single attack that most people recover from within six months. In some cases, the disease can reoccur. Four of the people developed Guillain-Barré syndrome (GBS), a syndrome that damages the myelin of the peripheral nervous system and can lead to muscle weakness. It has a previously reported association with the Zika virus.
When they were discharged from the hospital, five of the six people still had problems with motor functioning. One person had vision problems and one had problems with memory and thinking skills.
Tests showed that the participants all had Zika virus. Tests for dengue and chikungunya were negative.
“This doesn’t mean that all people infected with Zika will experience these brain problems. Of those who have nervous system problems, most do not have brain symptoms,” said Ferreira. “However, our study may shed light on possible lingering effects the virus may be associated with in the brain.”
“At present, it does not seem that ADEM cases are
occurring at a similarly high incidence as the GBS cases, but these findings
from Brazil suggest that clinicians should be vigilant for the possible
occurrence of ADEM and otherimmune-mediated illnesses of the central nervous
system,” said James Sejvar, MD, with the Centers for Disease Control and
Prevention in Atlanta and a member of the American Academy of Neurology.
“Of course, the remaining question is ‘why’-why does Zika virus appear
to have this strong association with GBS and potentially other immune/inflammatory
diseases of the nervous system? Hopefully, ongoing investigations of Zika
virus and immune-mediated neurologic disease will shed additional light
on this important question.”
New research supports
Zika virus-microcephaly link
The authors say that quantifying the risk may help better inform the broader public health response. Although the risk of microcephaly associated with Zika virus infection is relatively low compared to other maternal infections, the authors say that the association remains an important public health issue because the risk of Zika virus infection is particularly high during outbreaks, such as the current one in South America.
Commenting on the finding, Dr New research supports Zika virus-microcephaly link Laura Rodrigues, London School of Hygiene & Tropical Medicine, UK, said: “The finding that the highest risk of microcephaly was associated with infection in the first trimester of pregnancy is biologically plausible, given the timing of brain development and the type and severity of the neurological abnormalities.”
She noted that more research is needed. “Further data
will soon be available from Pernambuco, Colombia, Rio de Janeiro, and
maybe other sites…The fast production of knowledge during this epidemic
is an opportunity to observe science in the making: from formulation of
WHO EMR issues guide
to keep region free of Zika
The meeting concluded with agreement on a set of recommendations for urgent implementation in order to keep the Region free from the threat of Zika virus infection. These included to:
WHO will implement this plan over the next several months in the Region, in collaboration with ministries of health and other regional and international health partners.
The WHO says new studies on Zika and its complications are being published daily and the pace of research will continue to increase. The organisation says it will – with its partners – evaluate new studies to track any changes in the direction of the evidence base and to identify knowledge or research gaps.
The WHO says that “to allow publication of the latest evidence at regular intervals, a living systematic review is being developed. This will be an online summary of health research, which will be updated as new research becomes available.”
What is worrying about Zika is how much we don’t know. The US Centers for Disease Control and Prevention (CDC) issued a statement outlining the gaps in our knowledge of transmission of Zika.
What we know
What we do not know
Date of upload: 15th May 2016
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