As Kerala is witnessing a surge in the Nipah virus cases, a 24-year-old health worker, who came in close contact with a Nipah patient tested positive on Wednesday taking to infected people numbers to five.The state government has announced containment zones and restrictions to stop the spread of the virus. However, the contact list of the patients has become a reason for worry as 700 people have come into contact with the patients.According to Kerala Health Minister Veena George, out of these 700, about 77 are in the high-risk category.Here are the latest Nipah update in Kerala: According to the advisory, the high-risk Nipah patients have been asked to remain inside their houses. The routes of the two deceased patients have been published so that people avoid taking those routes.Restrictions have been imposed banning the gathering of a large number of people at festivals and functions in Kozhikode district.In just Kozhikode, 58 wards across nine panchayats in Vadakara taluk of the district, have been declared as containment zones. Only essential services and entry and exit are allowed in these areas. Shops selling goods will function only from 7 am to 5 pm.No time has been given for pharmacies and health centres. Buses or vehicles running on national highways through containment zones are not allowed to stop in the affected areas.Around 700 people came into contact with the patients and 76 of them are high risk. The minister said they are all stable.As the outbreak of Nipah took place in Kozhikode this time, Minister Veena George said the entire Kerala is prone to getting such infections according to WHO and ICMR studies.The Nipah strain found in Kerala this time is the Bangladesh variant which is less infectious but has a high mortality rate. This strain spreads from human to human.What is Nipah virusNipah virus (NiV) is a zoonotic virus, which is transmitted from animals (such as bats or pigs) to humans. It can also be transmitted through contaminated food or directly between people. Fruit bats of the Pteropodidae family are said to be the natural host of Nipah virus.What are symptoms of Nipah virusNotably, the Nipah virus can cause a range of illnesses in an affected person from asymptomatic (subclinical) infection to acute respiratory illness and fatal encephalitis.According to the World Health Organization (WHO), infected people initially develop symptoms including fever, headaches, myalgia (muscle pain), vomiting and sore throat. This can be followed by dizziness, drowsiness, altered consciousness, and neurological signs that indicate acute encephalitis.The incubation period of this virus is believed to range from 4 to 14 days. However, an incubation period as long as 45 days has been reported.What is recovery rate of Nipah virus Most people who survive acute encephalitis make a full recovery, but long-term neurologic conditions have been reported in survivors. Nearly, 20 per cent of patients are left with residual neurological consequences such as seizure disorder and personality changes. A small number of people who recover subsequently relapse or develop delayed onset encephalitis.Moreover, the case fatality rate is estimated at 40 per cent to 75 per cent. This rate can vary by outbreak depending on local capabilities for epidemiological surveillance and clinical management.