There has been a seven-fold increase in cases of Ross River virus in NSW over the past year, health authorities warn.

So far there have been 540 reported cases compared with 80 cases during the same period last year the Health Department says.

This latest news comes on the back of the first documented case of Ross River virus (RRV) infection transmitted by blood transfusion.

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Writing in this week’s MJA the researchers from Perth say the recipient had a clinically compatible illness, and RRV infection was confirmed by serological tests. The donor also had confirmed disease.

Transfusion transmission of RRV no longer appears to be only a theoretical risk, they say.