United go in search of back-to-back wins this weekend following last Friday's 1-0 win over Wolves, which ended a run of three successive defeats.
Scotland winger Fraser was withdrawn injured during that victory, while former Arsenal midfielder Willock missed out with a knock.
And Howe says he is hopeful that both players could be available for the game against Brendan Rodgers' men, who have lost just one of their last five league outings.
"I don't think (Fraser’s injury) is too bad, but it was enough to bring him off. We had a scan with him and it showed a very small problem, so hopefully it wont be too long for him. We'll have to see whether he makes this game," he said.
"Joe's made good progress, he's trained this week, and we hope to have him fit. As I sit here now, we've got a bit of illness in the camp – that's sort of been with us for most of the season to be honest, so we're looking at that closely."
Leicester prevailed in their Europa League quarter-final against PSV Eindhoven on Thursday, winning 2-1 on aggregate to book their place in the last four.
But Howe feels their midweek exertions won't have much of an impact on Sunday's game, such is the strength in the Foxes' squad.
"I've been in the situation before where we've played teams after they've played in Europe. To be honest, my experience is that it doesn't have too much bearing on the next game. I think they've got a squad to cope – they've got a very good group of players," he said.
"They've had a lot of injuries throughout the season but they've now returned, so their squad looks a lot stronger, and they've got a manager who is very experienced at managing the situation. In my experience, it's never really influenced the next game at all so we expect a full strength Leicester who are in very good form."
Chris Wood’s penalty was enough to seal the points against Wolves last time out, banishing the memory of the recent defeats to Chelsea, Everton and Spurs.
Magpies boss Howe believes that result provided his side with a huge boost – and he is eyeing a repeat performance against the FA Cup holders this weekend.
"I think it's naturally been a big lift for the group," he said. "No-one wanted to see that losing run continue, and although it was on the back of a really good run before that, I think we were well aware that we needed to respond and respond quickly, especially in front of our own supporters.
"Those nights at home have been so special for us and it was another one of those for us, under the lights. I thought it was a brilliant night and a big win for us – and now we have to try and back that up with another performance against an in-form team."
Howe also provided United supporters with an update on the fitness of key duo Kieran Trippier and Callum Wilson, who are both working towards a return to first team action.
“Personally they're OK – they’re both in a good place and they're both improving in line with what we expected,” he explained. "Kieran is very slightly ahead of schedule – he's beginning to run back on the grass with his boots on, so that's a great sign for us. He's still got to build up his fitness and everything that comes with that, but he's in a good place.
"Callum's the same. He's hitting balls towards the goal – there's no goalkeeper in at the moment, so it's only against mannequins – but he's gradually building up to where he wants to be, so it's great to see."
