Struck down by a mystery virus during the past month, Sharks forward Jayson Bukuya is back on the field and eager to contribute.

Bukuya spent a week in hospital fighting off the illness but baffled doctors couldn't figure out the cause. He struggled to keep food down and lost around seven kilograms as a result.

"It was a bit of a strange one. I was crook for a couple of weeks and they couldn't work out what was going on with me," Bukuya said. "It knocked me around for a little bit."

After missing three matches, the second-rower made a successful comeback in last Sunday's 22-16 win over the Bulldogs, churning out 39 tackles in a solid 55-minute stint from the bench.

While he didn't appear to miss a beat, Bukuya said he was breathing heavier than usual as he sets about regaining match fitness and weight.

"I was buggered. I was absolutely buggered," he laughed.

"I just need to do a bit more training because I haven't done a whole lot. I'm just trying to ease my way back into it. Now I can pick up the load and I should get back on track pretty quickly.

"(But) it's definitely better to be playing than watching, that's for sure."

Bukuya was one of many high-profile Cronulla players in the casualty ward in recent rounds, joining the likes of Wade Graham, Luke Lewis, Paul Gallen and Josh Dugan.

However, Bukuya said he had full confidence in the crop of youngsters called up to first grade amidst the injuries and was very pleased to see the team succeed.

"I was happy for them and I was happy for the boys that got the chance to come in and make their debuts. It was good to get the wins without (the players) that were out."

He pointed to a unified club culture and a strong pre-season as the reason everyone in the Sharks squad is able to perform well in the NRL when needed.

"I think it's just about knowing your role when you get your opportunity. We had a pretty good off-season this year and all the young blokes coming in knew what they had to do," he explained.

"They didn't really play outside of their roles; they just did their roles which made a big difference."

With Lewis and Graham named to return in the starting back-row this weekend, Bukuya will again come off the interchange and play wherever required – a role he's more than content to fill.

"I'm just happy to do a job for a team. Whether I get put in the middle or on the edge, hopefully I can just do a job for the team and do it well."

Although the Sharks have now won five consecutive matches for the first time since their premiership-winning 2016 season, Bukuya insisted the side is intent on staying grounded.

"I know that we're winning games and we're going good at the moment, but I feel like amongst the group we still know we've got a lot of work to do," he said.

"We've still got our heads down and we're not focusing too much on our (winning streak), we're just thinking about the next game."

That next game is an away clash with the Newcastle Knights this Sunday at McDonald Jones Stadium. Despite Newcastle losing its previous three matches, Bukuya said the Sharks were anticipating a tough challenge.

"I reckon it's going to be a pretty close game up there. They're a good side and they've been getting better the last couple of years. They've got a young team, a young forward pack, (and are) really enthusiastic.

"We're going to have to match them, that's for sure."