The siblings had reached India along with their parents from New York on June 10. Since they are too young to be quarantined, the sister-brother duo are being accompanied in hospital by their grandfather, who was put on anti-viral drugs and has tested negative for H1N1 virus.
The family members are also being tested and their samples have been sent to the National Institute for Communicable Diseases for tests.
A 24-year-old student, who came to Hyderabad from Austin in US via Dubai-Mumbai, was admitted to hospital for showing swine flu like symptoms. Hyderabad has the maximum number of nine swine flu cases in the country, followed by Delhi at five, Coimbatore two and Goa one.
In Tamil Nadu, a family of five, including a six- month-old infant, was quarantined at the airport with suspected symptoms after they arrived from the US.
Airport officials said Muralitharan (44), his wife Sarika (35) and their three daughters, aged five and three and the baby, were found to be suffering from cough, cold and fever, after they were examined by a special medical team stationed at the airport.
The doctors quarantined them immediately and sent them to the Communicable Diseases Hospital at Tondiarpet in Chennai for further medical attention, officials said.
Coimbatore-based Muralitharan and his family had arrived at Chennai by a Lufthansa flight around 2.30 am on Saturday. Union Health Ministry officials said the screening of passengers from affected countries was continuing at all the 21 international airports.
The government is also planning to install thermal scanners at all the major international airports beginning with Delhi. It has also asked Indian missions abroad to tell passengers with symptoms of swine flu to defer travelling to the country.
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