New Delhi - Twenty-nine people have died of hepatitis in Sabarkantha district of India's Gujarat state in the past fortnight, officials said Friday.

Sabarkatha district collector M Thennarasan said the disease was a mutant form of the hepatitis B virus. He said more than 40 people had been hospitalized with suspected infection.

The hepatitis B virus is usually transmitted through body fluids and, therefore, rarely occurs in very large numbers. It can be transferred through blood transfusion, infected needles or unprotected sex.

The virus causes fever, muscle or joint pain, loss of appetite, nausea and vomiting and in acute cases can lead to death.

Thennarasan said it was unclear what caused the disease outbreak and an investigation was being conducted by health authorities.

Charges had been filed against some doctors of local clinics on suspicion of using infected needles, PTI news agency reported.

Teams from specialist institutions in Delhi and the southern city of Pune had arrived in Sabarkantha to assist in treatment and investigations. (dpa)