ZIKA VIRUS DISEASE
ZIKA VIRUS DISEASE
History
1947
In the year of Indian Independence, in 1947,
Zika virus first identified in Uganda in Monkeys in Zika forest area.
(picture of Zika forest, Uganda)
1952
Zika virus identified in Human in Uganda and
Tanzania.
From the
1960s to 1980s
Human infections were found
across Africa and Asia, typically accompanied by mild illness.
2007
1st outbreak occurred
in Island of Yap (Micronesia).
July 2015
Brazil reported association of
Zika virus infection and “Gullain barre” syndrome
In October
2015
Brazil reported an association
between Zika virus infection and microcephaly.
Global situation
Zika virus has been steadily spreading around
the globe in areas where the Aedes mosquito is present. As of the 19th of
October 2016, 73 countries are reported to have had Zika virus cases since
2007, 56 since 2015
In India
15
May 2017, the Ministry of Health and Family Welfare-Government of India (MoHFW)
reported three laboratory-confirmed cases of Zika virus disease in Bapunagar
area, Ahmedabad District, Gujarat, India.
3
cases were reported.
·
A 34 year old female delivered
a clinically well baby at B.J. Medical College, Ahmedabad, Gujarat and
developed low grade fever after delivery. RT-PCR test confirmed the case as
Zika virus infection. The sample was re confirmed as Zika virus at NIV, Pune.
·
In January 2017, 22-year-old pregnant female in her 37th week of
pregnancy has been tested positive for Zika virus disease. In Ahmedabad.
·
In February 2017 64-year-old male
presenting with febrile illness of 8 days’ duration (negative for dengue
infection) was found to be positive for Zika virus at BJMC, Ahmedabad.
·
Measure were taken accordingly.
Among other measures, In addition to National Institute of Virology, Pune, and
NCDC in Delhi, 25 laboratories have also been strengthened by Indian Council of
Medical Research for laboratory diagnosis. In addition, 3 entomological
laboratories are conducting Zika virus testing on mosquito samples.
Transmission of
Disease
Zika virus is primarily
transmitted to people through the bite of an infected mosquito from the Aedes genus,
mainly Aedes
aegypti in tropical regions. Aedes mosquitoes
usually bite during the day, peaking during early morning and late afternoon or
evening. This is the same mosquito that transmits dengue, chikungunya and
yellow fever.
Though Aedes mosquito also
transmit dreaded disease like Dengue, but Dengue is not transmitted sexually, but
Sexual transmission of Zika virus is also possible.
Other modes of transmission such
as blood transfusion are being investigated.
Incubation period
The incubation period (the time
from exposure to symptoms) of Zika virus disease is not clear, but is likely to
be a few days.
Sign and sympton
The symptoms are similar to
other arbovirus infections such as dengue, and include fever, maculopapular
skin rashes, conjunctivitis, muscle and joint pain, malaise, and headache,
nausea etc
These symptoms are usually mild
and last for 2-7 days.
Complications
of zika virus disease
1. WHO has concluded that Zika virus infection during pregnancy is a cause
of congenital brain abnormalities, including microcephaly; and that
2. Zika virus is a trigger of Guillain-Barré syndrome.
3. Intense efforts are continuing to investigate the link between Zika
virus and a range of other neurological disorders.
Mechanism of fetal
infection
·
Transplacental
passage durig 1st trimester
·
Placental
macrophages and trophoblast
·
Infection
impairs placental function
·
Other
mechanism
Fetal complication
·
Microcephaly-
small head
·
Nervous
system abnormality
·
Fetal
growth retardation
Mechanim of
microcephaly and cns abnormalities
·
Virus
likely to involve its surface glycoprotein E interact with neural cell surface
receptor
·
Attenuate
growth and causes apoptosis of nerve cell (in vitro)
Diagnosis
Infection with Zika virus may be
suspected based on symptoms and recent history of travel to known Zika virus
endemic area
A diagnosis of Zika virus
infection can only be confirmed through laboratory tests on blood or other body
fluids, such as urine, saliva or semen
Zika virus has been detected in whole blood
(also serum and plasma), urine, cerebrospinal fluid, amniotic fluid, semen and
saliva. There is accumulating evidence that Zika virus is present in urine and
semen for longer periods than in whole blood or
saliva.
So, whole blood, serum, urine to be collected
for testing.
WHO recommends, where possible, other specimen
like, saliva, seamen, product of conception CSF also to be collected.
For Nucleic Acid Testing (NAT):
Whole blood and serum to be collected from
patient presenting fever </= 7 days of fever. The presence of Zika virus may
be confirmed by using NAT such as RT-PCR to detect targets on the virus genome
specific for Zika virus.
For serology (IgM testing):
Serum from patient with > 7 days fever.
Ideally two sample too be collected 2-3 weeks apart. Recommended serological
assays include enzyme immunoassays (EIAs) and immunofluorescence assays (IFA)
detecting IgM antibodies using viral lysate, cell culture supernatant or
recombinant proteins as well as neutralization assays such as plaque-reduction
neutralization tests (PRNT). IgM detection should be performed for pregnant
women in areas of endemic transmission or pregnant women who could have had
contact with vectorborne or sexually transmitted Zika virus
NAT should be tested with < 7 days fever,
and Serology and/or NAT for > 7 days fever.
In general, a reactive result for Zika virus
IgM in the absence of IgM to dengue or other flaviviruses suggests recent
exposure to Zika virus
In all other circumstances it is recommended
that specimens be kept refrigerated at 2-8ºC and tested within 48 hours. If
there is a delay of more than 48 hours before testing, serum should be
separated and stored separately. All types of specimens may be kept frozen at
-20°C for up to 7 days. For storage longer than 7 days, specimens should be
frozen at -70°C.
Treatment:
Zika virus disease is usually
mild and requires no specific treatment.
1.
People sick with Zika
virus should get plenty of rest, drink enough fluids, and t
2.
reat pain and fever with
common medicines.
3.
If symptoms worsen, they
should seek medical care and advice.
4.
There is currently no
vaccine available
Prevention:
1.
Mosquito bite :
a.
BY wearing long cloth, using physical
barrier like window screen, closing doors and window, sleeping inside mosquito
net, using mosquito repellent use etc. children should be given special care.
b.
Mosquito control by abolishing
mosquito breedind sites. Do not keep clean drum, pot, buckets around house.
c.
Community effort to keep the area
clean and government policies to eradicate mosquito also help.
- Sexual transmission:
1.
AS Zika virus transmit through sexual intercourse, regions
with active transmission of Zika virus, all people with Zika virus infection
and their sexual partners should receive information about the risks of sexual
transmission of Zika virus.
2.
WHO recommends that sexually active men and women be
correctly counselled and offered a full range of contraceptive methods to be
able to make an informed choice about whether and when to become pregnant in
order to prevent possible adverse pregnancy and fetal outcomes.
3.
Pregnant women should practice safer sex or abstain from sexual activity for at least
the whole duration of the pregnancy.
4.
For regions with no active transmission of Zika
virus, WHO recommends practising safer sex or abstinence for a period of six
months for men and women who are returning from areas of active transmission to
prevent Zika virus infection through sexual intercourse.
5.
Sexual partners of pregnant women, living in or
returning from areas where local transmission of Zika virus occurs should
practice safer sex or abstain from sexual activity throughout the pregnancy.
WHO (World Health Organisation) risk assessment
Zika
virus is known to be circulating in South East Asia Region and these findings
do not change the global risk assessment. WHO encourages Member states to
report similar findings to better understand the global epidemiology of Zika
virus.
The
risk of further spread of Zika virus to areas where the competent vectors, the
Aedes mosquitoes, are present is significant given the wide geographical
distribution of these mosquitoes in various regions of the world.
WHO advice
Prevention
and control relies on reducing mosquitoes through source reduction and reducing
contact between mosquitoes and people.
WHO
does not recommend any travel or trade restriction to India based on the
current information available
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