It did not clear up with medication and he returned to the resort for a second holiday last November.
Less than a month later, the retired laboratory engineer was taken to Whiston Hospital with severe breathing problems. His son, Mark Farnworth, 42, also from St Helens, said: "I feel like we have been robbed.
"My dad didn't remember being bitten and by the time it was diagnosed it was too late - that's the scary thing.
"There was no indication and as time went on he carried on as normal but he started feeling unwell the week before Christmas.
"He went to his GP thinking he had picked up the flu and by then he had developed quite a hard cough to the point his ribs were hurting.
"We had to take him to Whiston Hospital's casualty department - he found breathing really difficult."
Mr Farnworth's symptoms baffled doctors, who failed to diagnose his condition after a series of tests, and transferred him to the Royal Liverpool Hospital where he died on January 11.
Infected blood from a sandfly bite stopped his liver functioning and led to multiple organ failure, the coroner's court heard.
Mr Farnworth's family last night warned holidaymakers to take any bites seriously.
His daughter Gaynor Winstanley, 42, said: "Before we even had a chance to react it was too late.
"There are no vaccinations for sandfly infection and there are no recognisable symptoms until you are in the late stages of the illness."
His son added: "He was an exceptionally fit man for his age who loved fell walking in the Lake District, playing golf and even going to the gym.
"For him to be taken away like this is heartbreaking.
"He was just in the wrong place at the wrong time."
Assistant deputy coroner Simon Holder recorded a verdict of accidental death.
Deadly sandfly infection very rare, says expert>>>
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