World Health Organisation (WHO) on 1 February 2016 declared Public Health Emergency of International Concern over the explosive spread of the mosquito-borne Zika virus. Incidentally, the declaration came just two weeks after the end of Ebola outbreak in West Africa that killed around 11000 people in the region.
Against this backdrop, it is pertinent to understand the nature of the Zika virus, its spread and ways to mitigate its potential outbreak.
Where does Zika virus occur?
Zika virus occurs in tropical areas with large mosquito populations and is known to circulate in Africa, the Americas, Southern Asia and Western Pacific. The virus was discovered in 1947, but for many years only sporadic human cases were detected in Africa and Southern Asia.
In 2007, the first documented outbreak of Zika virus disease occurred in the Pacific. Since 2013, cases and outbreaks of the disease have been reported from the Western Pacific, the Americas and Africa.
Given the expansion of environments where mosquitoes can live and breed, facilitated by urbanisation and globalisation, there is potential for major urban epidemics of Zika virus disease to occur globally.
How do people catch Zika virus?
People catch Zika virus by being bitten by an infected Aedes mosquito – the same type of mosquito that spreads dengue, chikungunya and yellow fever.
Where can the Aedes mosquito survive?
There are 2 types of Aedes mosquito capable of transmitting the Zika virus – Aedes aegypti and Aedes albopictus.
In most cases, Zika spreads through the Aedes aegypti mosquito in tropical and subtropical regions. The Aedes aegypti mosquito does not survive in cooler climate temperatures.
The Aedes albopictus mosquito can also transmit the virus. This mosquito can hibernate and survive cooler temperature regions.
Can the Aedes mosquito travel from country to country and region to region?
The Aedes mosquito is a weak flyer; it cannot fly more than 400 meters. But it may inadvertently be transported by humans from one place to another, for example in the back of the car and plants.
What are the symptoms of Zika virus disease?
Zika virus usually causes mild illness; with symptoms appearing a few days after a person is bitten by an infected mosquito.
Most people with Zika virus disease will get a slight fever and rash. Others may also get conjunctivitis, muscle and joint pain, and feel tired. The symptoms usually finish in 2 to 7 days.
What might be the potential complications of Zika virus?
Because no large outbreaks of Zika virus were recorded before 2007, little is currently known about the complications of the disease.
During the first outbreak of Zika from 2013 - 2014 in French Polynesia, which also coincided with an ongoing outbreak of dengue, national health authorities reported an unusual increase in Guillain-Barré syndrome.
A similar observation of increased Guillain-Barré syndrome was also made in 2015 in the context of the first Zika virus outbreak in Brazil.
In 2015, local health authorities in Brazil also observed an increase in babies born with microcephaly at the same time of an outbreak of Zika virus.
Health authorities and agencies are now investigating the potential connection between microcephaly and Zika virus, in addition to other possible causes.
However more investigation and research is needed before we will be able to better understand any possible link.
What is Guillain-Barré syndrome?
It is a condition in which the body’s immune system attacks part of the nervous system. It can be caused by a number of viruses and can affect people of any age. Exactly what triggers the syndrome is not known.
The main symptoms include muscular weakness and tingling in the arms and legs. Severe complications can occur if the respiratory muscles are affected, requiring hospitalisation.
What is microcephaly?
It is a rare condition where a baby has an abnormally small head. This is due to abnormal brain development of the baby in the womb or during infancy. Babies and children with microcephaly often have challenges with their brain development as they grow older.
Microcephaly can be caused by a variety of environmental and genetic factors such as Downs syndrome, exposure to drugs, alcohol or other toxins in the womb and rubella infection during pregnancy.
Can El Niňo have an effect on Zika?
The Aedes aegypti mosquito breeds in standing water. Severe drought, flooding, heavy rains and temperature rises are all known effects of El Niño—a warming of the central to eastern tropical Pacific Ocean.
An increase in mosquitos can be expected due to expanding and favourable breeding sites.
What is the situation in India?
So far there were no reported incidents of the virus in India. However, to contain its transmission the Union Government on 29 January 2016 formed a technical expert group to suggest measures to deal with the virus.
How is Zika virus disease diagnosed?
For most people diagnosed with Zika virus disease, diagnosis is based on their symptoms and recent history like mosquito bites or travel to an area where Zika virus is known to be present. A laboratory can confirm the diagnosis by blood tests.
How is Zika virus disease treated?
The symptoms of Zika virus disease can be treated with common pain and fever medicines, rest and plenty of water. If symptoms worsen, people should seek medical advice. There is currently no cure or vaccine for the disease itself.
How to protect oneself from the virus?
The best protection from Zika virus is preventing mosquito bites. Preventing mosquito bites will protect people from Zika virus, as well as other diseases that are transmitted by mosquitoes such as dengue, chikungunya and yellow fever.
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