Brazil grappling with money laundering scams, drinking water
crisis and political unrest is now racing towards a health epidemic of
dangerous proportions, the Zika Virus. The South American country all set to
unveil Rio Summer Olympics, biggest sporting fiesta on the planet in over six
months is now grappling with health emergency, Zika virus. Brazil emerged as
epicenter of Zika virus (ZIKV), a mosquito-borne disease transmitted by Aedes
sp. Zika virus, a member of flavi viridae family and is related to yellow
fever, west Nile and dengue fever virus. Zika is not contagious. The vital
modes of transmission modes are blood transfusions and mother-to-child
transmission. While the virus was believed to migrate through sexual contact,
there is no conclusive research evidence as yet.
The virus was first identified and isolated from a caged Rhesus
monkey in Zika forest of Uganda in 1947. In 1952 researchers isolated Zika
Virus from the serum of an affected human being in Uganda and Tanzania. Only
20% of the people infected by Zika virus will develop symptoms. The symptoms
are similar to those exhibited by other arbo virus like dengue and common
symptoms include fever, skin rashes, conjunctivitis, muscle and joint pains,
malaise and headache. Symptoms are mild and last for 2-7 days and hence no
specified treatment is recommended. Medicines used to treat common cold and
fever are usually prescribed. In absence of causalities dedicated research to
develop vaccines weren’t initiated on large scale. But now with recent outbreak
of the epidemic in Brazil, pharmaceutical majors are now focusing attention
towards vaccine development. Researchers believe that it would take at least 5
years to develop vaccine for Zika virus. Thus far, the only preventive measure
against Zika virus is effective control of vector (mosquito) population.
WHO is predicting an outbreak and major countries have issued
travel advisory asking pregnant women from traveling to affected countries. Zika
is speculated to spread to both Americas except Canada and Chile. Since May
2015 the viral infection has spread to 21 countries. Lack of immunity among the
population and prevalence of Aedes mosquito, the carrier of the disease led to
surge in infection levels. Unfortunately controlling spread of disease in
highly interconnected world has now become an arduous task. Mosquitoes are now
considered the worst enemies of mankind for being vectors of several
devastating diseases like Malaria, dengue fever killing hundreds and thousands
of people.
Environmentalists said that urbanization and deforestation
created ideal conditions for the multiplication of disease causing vectors. Following
explosive spread of Zika virus, Brazilians are under intense international
pressure to curtail the vector population. They have adopted a judicious mix of
old and new mosquito controlling strategies to contain the viral transmission.
Genetically engineered mosquitoes harboring a lethal gene are released in the
outskirts of cities. GM mosquitoes breed with native population and the gene
when passed onto the offspring dies before reaching adulthood. Consequently,
the vector population is now precisely kept under check. Biotech companies have
now devised genetic overdrive methods like spreading sterility trait in Aedes
to rapidly control virus carrying vectors. Another approach is infecting
mosquitoes with Wolbachia bacterium, which prevents mosquito from carrying the
virus. Bacterium is passed onto the subsequent generations through infected
eggs thus the lethal effects of mosquito bites are overcome.
First well documented case of Zika virus was described in
1968 when no potential fatalities were reported. Three potent lineages of Virus
were identified- two from African and one from Asian. From 1951 to 1981 human
infections were reported in African countries and in parts of India, Indonesia,
Malaysia, Thailand, Philippines and Vietnam. The viral strains now found in
Americas bear close similarities with the French Polynesian strains. The virus
for several decades remained benign since its first. The first major outbreak
of Zika occurred in Yap island of Federated States of Micronesia. By 2013 it spread
to French Polynesia where the infected persons were diagnosed with severe
neurological problems including the occurrence of rare disorder Guillain Barre
Syndrome. It is an auto-immune disease that occurs when the immune system
attacks the peripheral nerves causing muscle weakness, tingling, loss of
sensation and eventually total paralysis. Within span of three months of viral
infection, 40 such cases were reported in Yap island. Incidentally the virus
caught the attention of researchers as it spread to Australia, France, Japan,
Norway and Easter Island.
In 2014, the viral genome was decoded. The single stranded
positive RNA virus with the help of host cell machinery replicates and churns
out smaller proteins-which includes the capsid, membrane, envelope and seven
non-structural proteins. The virus infects the host cell, invades the immune
system and takes over dendritic cells. Researchers believed that the three
lineages of the virus might have evolved from Uganda in 1920 and through series
of recombination events, it has become more adaptive. In May 2015, the virus
made its first appearance in South America in Brazil. Perhaps it was imported
into the region during the FIFA cup of 2014 and was spread through the bite of
Aedes sp mosquitoes. Health experts estimated that by around 2015 around
million people might have been infected. Since the outbreak of disease in 2015 there
has been whopping increase in the birth of babies with microcephaly in Brazil.
While Zika virus was suspected to have caused the birth defect, definite links
are not yet established. But viral
traces are found in the amniotic fluid, placental tissues, miscarried babies
and in the brains of the babies died of microcephaly immediately after birth.
While strong links suggests that Zika virus had caused the genetic-defects in
the newborn babies, the immune responses of Zika virus are hard to detect. Zika
virus is becoming hard to detect because of its similar immune responses as of
dengue virus and most of the Brazilian population are exposed to dengue virus
too. Researchers opine that the relatively mild Zika virus due to continued
genetic changes is now predisposed to acquire disease-sparking capabilities.
With disproportionate increase in number of microcephalic
infants in Brazil researchers are more worried about the resurgence of a viral
outbreak. Microcephaly is characterized by four malformations-loss of large
degree of brain tissue, unusually smooth and wrinkleless brains, numerous
calcium deposits and smaller cerebellums. Unfortunately microcephalic condition
of the fetus in most cases, cann’t be detected with ultrasound scans during the
first 20 weeks in expectant mothers. It is towards the end of second trimester
usually genetic defects can be detected with ultrasound. By 24 weeks aborting a
foetus is risky and not legally approved. Sometimes microcephalic condition remains
undetected and appears when babies are born. The affected children display
varied mental disabilities- intellectual abilities are stunted, communication
is hindered. They may be profoundly disabled and might be confined to wheel
chairs for the rest of their lives. In wake of the severity of the disease,
Centre for Disease Control and WHO advised women to delay pregnancy and asked
to avoid travelling to the affected regions. With Zika virus gradually
transcending the boundaries of Latin American countries, US is now highly
worried at the propensity of Zika becoming a pandemic in Americas. Health
experts as of now, squashed such worries and believed that Zika by and large
might cause localized infections in few clusters in US if any. The robust
health and sanitation system is geared up to avert any major health threat to
US. On the contrary, Indian health experts expressed severe concerns about a
possible Zika outbreak as the country regularly encounters outbreak of dengue
and chikungunya caused by the bite of Aedes aegypti mosquito, carrier of Zika
virus. Traces of Zika were detected in India in 1952-53 but there was no reported
outbreak. With 26 million children born every year India is at high risk.
@ Copyrights reserved.
