Viral respiratory tract infections -- like the common cold, flu, tonsillitis, bronchitis and pneumonia -- during the first six months of life are likely to increase the risk for Type-1 diabetes in children, says a new study.

The findings suggest that the first half-year of life is crucial for the development of the immune system and of autoimmune diseases such as Type-1 diabetes (T1D).

According to researchers, T1D risk increased in children who had a respiratory tract infection between birth and 2.9 months or between three and 5.9 months of age compared with children who had no respiratory tract infections in these age intervals.

"Our findings show that viral respiratory tract disorders during the first six months of life significantly increase the risk of children developing Type-1 diabetes," said one of the researchers, Andreas Beyerlein, from Helmholtz Zentrum Munchen in Germany.

Infants are particularly susceptible to respiratory tract infections like the common cold, flu, tonsillitis, bronchitis and pneumonia, because, unlike adults, their immune systems have not acquired the immunity to stave off some of the viruses that cause them.

The study included 295,420 infants, of whom 720 were diagnosed with T1D over a median follow-up of 8.5 years, for an incidence of 29 diagnoses per 100,000 children annually.

At least one infection was reported during the first two years of life in 93 percent of all children, and in 97 percent of children with T1D.

Most children experienced respiratory and viral infections.

T1D risk was also found increased among children who experienced a viral infection between birth and 5.9 months of age.

The study was published in the journal JAMA.