WHO declared a Public Health Emergency of International concern on 1 February after a substantial spike in cases of microcephaly and Guillain-Barre syndrome in the Americas. These cases are strongly suspected to be linked to Zika virus, a mosquito transmitted disease that has spread to more than 25 countries and territories in the region. The virus is known to circulate in Africa, the Americas, Asia and the Pacific.

Zika virus is recently associated with potential complications such as neurological disorders and neonatal malformations and Researchers are also studying the possible link between Zika virus infection and microcephaly.

Zika virus disease is caused by a virus transmitted by bite of an infected Aedes mosquitoes, this is the same mosquito that transmits dengue, chikungunya and yellow fever. People with Zika virus disease usually have a mild fever, skin rash (exanthema) and conjunctivitis. These symptoms normally last for 2-7 days. There is no specific treatment or vaccine currently available.

Mosquitoes and their breeding sites pose a significant risk factor for Zika virus infection. Prevention and control relies on reducing mosquitoes through source reduction (removal and modification of breeding sites) and reducing contact between mosquitoes and people.

This can be done by using insect repellent; wearing clothes (preferably light-coloured) that cover as much of the body as possible; using physical barriers such as screens, closed doors and windows; and sleeping under mosquito nets. It is also important to empty, clean or cover containers that can hold water such as buckets, flower pots or tyres, so that places where mosquitoes can breed are removed.

India’s Health Ministry issued health advisory, appointing National Centre for Disease Control (NCDC); as the nodal agency for investigation of outbreak- should the situation arise. This comes in the backdrop of the World Health Organisation designating the Zika virus and its suspected complicationsi n newborns as a public health emergency of international concern earlier this week.

Microcephaly is a condition where a baby’s head is much smaller than expected. During pregnancy, a baby’s head grows because the baby’s brain grows. Microcephaly can occur because a baby’s brain has not developed properly during pregnancy or has stopped growing after birth, which results in a smaller head size. Microcephaly can be an isolated condition, meaning that it can occur with no other major birth defects, or it can occur in combination with other major birth defects.

Guillain-Barré syndrome: The syndrome is triggered by an infection and can cause temporary or long-term paralysis. The exact cause of Guillain-Barré syndrome is still unclear, but it generally develops after a lung or gut infection and appears to be an autoimmune disease. This means that symptoms are caused by our own immune system attacking our body.

The initial infection can be caused by either bacteria or viruses, and a large number of infections have been linked to Guillain-Barré syndrome. The most commonly associated infections are the bacteria Campylobacter jejuni, cytomegalovirus and Epstein-Barr virus.

When we get an infection, our immune system will learn to fight off the invader. It does this by developing antibodies, which are molecules that can attach to the surface of the bacteria or virus. These antibodies attach to a specific pattern or shape on the surface of the bacteria or virus. When they are attached they act as a target that our immune cells will attack and kill.

In Guillain-Barré syndrome, our immune system makes a mistake – sometimes a similar pattern or shape to the one on the bacteria or virus is also on the surface of our nerve cells. When the antibodies attach to the surface of our nerve cells, they still act as a target. As a result, our immune cells then attack our own nerve cells. They can range from mild numbness and weakness, to death.

Dengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes. It is an acute illness of sudden onset that usually follows a benign course with symptoms such as headache, fever, exhaustion, severe muscle and joint pain, swollen lymph nodes , and rash. The presence of fever, itchy rash, and headache (the “dengue triad”) is characteristic of dengue. Other signs of dengue fever include bleeding gums, severe pain behind the eyes, and red palms and soles. Dengue goes by other names, including “breakbone fever” or “dandy fever.” Victims of dengue often have contortions due to the intense joint, muscle, and bone pain, hence the name breakbone fever.

Chikungunya is a viral disease transmitted to humans by infected mosquitoes. It causes fever and severe joint pain. Other symptoms include muscle pain, headache, nausea, fatigue and rash. Joint pain is often debilitating and can vary in duration. The disease shares some clinical signs with dengue, and can be misdiagnosed in areas where dengue is common.

There is no curefor the disease. Treatment is focused on relieving the symptoms. The proximity of mosquito breeding sites to human habitation is a significant risk factor for chikungunya.