The majority of those who have died of swine flu have been people who already suffered from respiratory ailments such as asthma and pneumonia, because, unlike seasonal flu viruses, the swine flu virus binds to the lungs and not just the nose and throat, recently published research suggests.
Most cases of swine flu so far have been mild, because as of now, the virus binds to the lungs only weakly, a team of researchers said in a study that appeared on Thursday in the journal Nature Biotechnology.
In India, less then three per cent of the 5,611 people who have tested positive for swine flu have died. Rain-related ailments and malaria have had far higher fatility rates.
To cite one comparison, in Mumbai, 41 people died of rain-related ailments in just two weeks in July, while 18 people have died of swine flu so far.
But the virus could become more fatal if it mutates in such a way that it learns to infect cells in the lungs more strongly, said the researchers, from Imperial College London, in England. Deep lung infections could lead to pneumonia and bronchitis, and would make the virus more dangerous.
“Most people infected with swine-origin flu...have experienced relatively mild symptoms," said Professor Ten Feizi, one of the study's authors. "However, some people have had more severe lung infections, which can be worse than those caused by seasonal flu. Our new research shows how the virus does this — by attaching to receptors mostly found on cells deep in the lungs (which) seasonal flu cannot do."
The researchers do not know whether the virus will undergo such a mutation. “That is the million-dollar question," said Randeep Guleria, pulmunologist at the Delhi’s All-India Institute of Medical Sciences and a leading authority on H1N1, the virus’ medical name. Evidence from previous pandemics is mixed. In the 1918 global flu pandemic the virus mutated to become more virulent. But in two subsequent ones, it remained benign.