Zika virus is a mosquito-borne virus first identified in Uganda in 1947. It causes mild fever and rash in most cases but has been linked to Guillain-Barré syndrome and microcephaly. The virus spread out of Africa and Asia, causing major outbreaks in French Polynesia in 2013 and Brazil in 2015. It is transmitted primarily by Aedes mosquitoes. While most cases are mild, the virus can be transmitted from mother to fetus during pregnancy and cause birth defects like microcephaly. There is no vaccine or treatment currently available, so prevention focuses on controlling mosquito populations and protecting against bites.

1. BY
MEGHA MANOJ MACHHAR

2.  It is a mosquito-borne viral infection, first
identified in Rhesus monkey of Zika forest in
Uganda in 1947, hence named Zika virus.
 In humans it was first identified in 1952 in
Uganda and United Republic of Tanzania and
the virus was first isolated in Nigeria in 1968.
 The sporadic cases of infection were reported
in Southeast Asia and Sub-Saharan Africa.

3.  It is a member of Flavivirus family that also
includes yellow fever virus, dengue virus,
Japanese encephalitis and West Nile virus.
 Its genome size is 10.8 kbp with positive strand
RNA enclosed in capsid and surrounded by
membrane.
 The membrane has (E) glycoprotein envelope
embedded in it that allows the attachment of viral
particles to the host cell receptors to initiate
infection.

4.  ZIKV moved out of Asia and Africa and caused an
epidemic in YAP islands of Micronesia (2007) and
French Polynesia, New Caledonia, The Cook
Islands and in Easter Islands in 2013 and 2014.
 In 2015 there has been an upsurge in ZIKV
infection dramatically in America with Brazil
being most affected; 444,000 to 1.3 million cases
reported through December 2015.
 It has been reported that ZIKV infection has spread
to 23 countries across America.

5.  It is transmitted by mosquito bites, belonging
to the genus Aedes, mainly Aedes agypti.
 Other members include A.africanus,
A.apicoargenteus, A.leuteocephalus, A.vitattus
and A.furcifer.
 A.albopictus was identified as the primary
vector for ZIKV transmission during 2007
Gabon outbreak.

6.  The person infected with ZIKV develop mild
symptoms that last for several days to a week.
 The symptoms include fever, rash, joint pain,
conjunctivitis, headache, malaise.
 In general the high incidences of Gullian Barré
syndrome and mirocephaly with rapid spread
of the virus have made the outbreak more
serious.

7.  The infection is diagnosed based on the
symptoms developed after exposure to the
virus particles via mosquito bites.
 The laboratory confirmation can be done from
the samples collected from blood and other
body fluids like urine and saliva.

8.  The association of the syndrome with ZIKV was
first observed during the French Polynesia
outbreak in 2013.
 It is an autoimmune disease which severely affects
the peripheral nervous system that results in
progressive muscle weakening.
 It is a rare immune system disorder with a
frequency of 0.4 to 4 people per 100,000 per year.
 The exact cause of GBS is unknown but is known
to be preceded by bacterial or viral infection.

9.  The first case of development of GBS seven days after
contracting the ZIKV was observed in a Polynesian
women.
 As per the reports from WHO Brazil, Venezuela,
Suriname, El Salvador and Colombia have observed a
surge in GBS development with the occurrence of
ZIKV.
 Brazil has reported that out of confirmed cases of GBS
62% has developed symptoms of ZIKV infection.
 The correlation of GBS and ZIKV is still unknown.
Researches are being carried out to figure out the
connection between the two.

10.  Like GBS , there has been an exorbitant rise in
Microcephaly cases with the development of
ZIKV.
 Microcephaly is neonatal malformation where
the newborn has reduced head size as
compared to the normal head size of healthy
infants.
 The exact link between ZIKV and birth defects
are yet to be discovered. Pregnant women are,
thus, cautioned to avoid travelling to places
with Zika virus outbreak.

11.  ZIKV can be transferred from mother to her fetus
during pregnancy.
 As per WHO, out of 79 reported deaths of infants due
to congenital malformation ZIKA virus has been
confirmed in the tissues of 5 fetuses in northeastern
Brazil.
 The reports by University of Sao Paulo have recorded
ocular abnormalities in infants with microcephaly and
ZIKV infection, from the state of Bahia, Brazil in 34.5%
of infants with microcephaly.
 The report has also documented that mothers of
79.3% of infants with microcephaly have shown
symptoms of ZIKV infection.

12.  Another report have documented a case of 25 year
old pregnant European lady working in Natal,
Brazil who developed fetal anomalies including
microcephaly at the 28th week of gestation.
Autopsy reports after termination of pregnancy
revealed severe brain defects and 42-54 nm viral
particles were detected in brain by electron
microscopy.
 On sequencing the viral genome it has been found
out that the viral particle had 99.7% similarity with
genome of Zika virus isolated from a patient in
French Polynesia during 2013 outbreak and a
strain from Sao Paulo in 2015.

13.  There has been evidence of sexual transmission of
ZIKV by men to his female counterparts. But there
is no evidence if women could transmit the virus
to their sex partners.
 Two cases have been reported where man had
shown symptoms.
 More research is required in this matter. As a
matter of concern, Centers for Disease Control and
Prevention (CDC) have recommended the men
who have lived or travelled to ZIKV infected areas
to abstain from sexual activities.

14.  Potential measures should be taken to eliminate
the mosquito breeding sites like water-filled
buckets, flower-pots , gutters, open tyres etc.
 Personal protection measures should be adopted
like wearing light-colored clothes, covering the
body to the maximum, using window screens,
keeping doors and windows closed, sleeping
under mosquito nets, etc.
 Using mosquito repellants that contain DEET
(N,N-diethyl-3-methlybenzamide), IR3535 (3-[N-
acetyl-N-butyl]-aminopropionic acid ethly ester),
Icaridin (1-piperidinecarboxylic acid, 2-(2-
hydroxyethyl)-1-methylpropylester)

15.  Use of insecticides recommended by WHO Pesticide
Evaluation Scheme may be used by health officials to
eradicate the breeding sites in large water containers.
 Blood donations and transfusion activities should be carried
under utmost care and precautionary measures.
 It is recommended to abstain from sexual activities if one
suffers from ZIKV infection.
 Pregnant women should take very proper care and
preventive measures to protect themselves from mosquito
bites and also should regularly be in contact with healthcare
professionals.
 It is recommended to avoid travel to ZIKV hit areas.

16. World Health Organization has declared the
Zika outbreak a global health emergency and
has left no stone unturned to combat its spread.
It has activated its Emergency Operations
Management System – Strategic Operation and
Joint Operations Plan, to provide support to the
afflicted countries and further figure out an
effective plan to control its outbreak and
spread to other areas. The details can be read in
the report:
http://apps.who.int/iris/bitstream/10665/20
4420/1/ZikaResponseFramework_JanJun16_en
g.pdf?ua=1

17. 1. Virology Blog, about viruses and viral disease.
www.virology.ws
2. World Health Organization, Media centre.
www.who.int
3. Centers for Disease Control and Prevention.
www.cdc.gov
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