On Valentine's Day they had a tea dance at Dad's care home, complete with paper hearts and soppy songs on request. At Christmas there was a huge tree, tinsel and a carol service. I am sure there were sprayed-on cobwebs at Halloween and bunting on the jubilee. When the days are interminable, any chance to mark and differentiate them can't be missed.

So arriving for a visit just before the Easter weekend, I am half expecting an egg hunt and someone in a rabbit suit. Or at least some half-decent hot cross buns. But when I get off the train in Penzance, toddler in tow, it soon becomes clear the reality will be less cosy.

"Dad's home is closed," says my sister when she picks me up. "There's been an outbreak of diarrhoea and vomiting. Most of the residents have got it and lots of the staff."

"Oh, no. That's terrible," I say, weakly. The thought of all the residents in his home being struck down with the norovirus is like something out of a horror film. Most of them are doubly incontinent anyway. Many can't walk without help. It must be chaos in there.

"You can still go and visit him later," she says. "He isn't vomiting – he has just got an upset stomach. They were keeping him in his room, but you are allowed to go down and see him if you want. At your own risk, they said."

"Ermm," I say, thinking of how long it is since I saw Dad, but also of how little I want to get the norovirus when six months pregnant. "How long is the home going to be shut for?"

I am down for a week. Even if I don't go in immediately, there will still be plenty of opportunity to see Dad.

"It's supposed to be closed for 48 hours after the last person fell ill," she says. "Give them a call in the morning and find out what's happening."

Later on, we all worry about Dad. Not just because of his immediate discomfort and the idea of him being alone in his room, but because for the past six months the weight has been dropping off him. It doesn't seem to matter how many roasts and treacle sponges are spooned into him, the pounds are melting away. Forget the 5:2 diet or Atkins, what's really effective is a stint on the dementia diet. Dad's gone from being robust and barrel-shaped to bird-like, all snappable clavicles and wrists. And he is not alone. None of the residents in his home are well-covered, even though they sit all day and eat heartily. It is almost as if whatever is destroying their brains absorbs all their energy.

At the recent meeting about Dad it was even decided that he should have some high-calorie energy drinks to supplement his diet, to try to reverse the trend. He can ill afford a stint of virus-induced starvation.

There is also the issue of dehydration. Getting enough liquid into him takes time and patience. Beakers of milky, tepid tea and squash are brought regularly throughout the day, with the number of millilitres consumed noted down. But if he is losing fluid at a rapid pace, it won't be easy to replace. He doesn't gulp down water thirstily – each sip is an effort.

So it is a relief when I call next morning to be told that he is much better and the home has been reopened. On the way to see him, I can't help hoping that the outbreak won't have ruined the chance of enforced Easter jollity. At the edge of life, when even a stomach bug is momentous, such rituals make more sense than ever.

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