What is it with the All Blacks and mumps? A second unrelated outbreak of the viral disease threatens to throw a serious spanner in the works of their back-three division to face France next weekend.

All Blacks coach Steve Hansen revealed shortly before the team decamped from London to Paris, via train, that star wing and contender for World Rugby's breakthrough player of the year award, Rieko Ioane, had come down with an untimely case of the mumps.

Hansen confirmed Ioane's outbreak was unrelated to the earlier case of mumps suffered by young midfielder Jack Goodhue that forced him to delay his departure from New Zealand and miss the chance to make his first appearance for the All Blacks, against the Baabaas at Twickenham on Saturday.

PHOTOSPORT Rieko Ioane could be out of the upcoming test against France thanks to a case of mumps.

The coach is also confident the right steps have been taken to ensure there is no spread of the virus through the All Blacks camp.

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"The doc has done a great job, and we've isolated him, so we're not worried about it spreading."

But Hansen did admit that Ioane's now cast-iron spot on the left wing for the first of three tests on this tour, against Les Bleus at the Stade de France on Saturday night (Sunday morning NZT), now had to be in doubt.

"It's unrelated to Jack Goodhue's because they haven't been in contact, but it has obviously come out of Auckland somewhere," Hansen said of Ioane's affliction.

"It will be touch and go though if he is available [to face France]. He trained this morning, so we'll just have to see how well he comes through the week."

If Ioane was to miss the French test it would be a major blow for the All Blacks as they look to finish their year on a high point, after already suffering two defeats and a draw through their 2017 programme.

The 20-year-old Auckland has become their principal strike weapon through an outstanding campaign in his first prolonged run of test rugby after being introduced on last year's November tour.

He has scored eight tries in his eight test appearances this year (he has 10 caps all told) and has been one of the All Blacks' most consistent performers through an impressive campaign. The 103kg human freight train has not only revealed an outstanding nose for the line, but he has been right up there in almost every other facet of his game.

He is excellent under the high ball, goes looking for work, is sound positionally and has a pretty fair distribution game too when the occasion warrants. He started the year at centre in Super Rugby but has made a fine fist of his shift to the wing and looks entrenched as the first-choice All Black No 11.

So well has Ioane played that the All Blacks coaches have had the luxury of jettisoning 54-test wing Julian Savea (with 46 tries) with the message he needs to have a big off-season and rediscover his enjoyment of the game.

Hansen shrugged off any concerns about his depleted back-three stock being reduced even further - "It's not too bad," he said of his options outside Ioane who also missed the third test against the British and Irish Lions with illness - but the reality is that with Ben Smith, Nehe Milner-Skudder and Israel Dagg all unavailable, and Savea unwanted, they have limited options.

Waisake Naholo looks to have the test right wing spot sewn up, and if Ioane were to miss the French clash, Seta Tamanivalu (three caps in 2016) would likely be next cab off the rank. The other specialist wing in the touring squad is North Harbour's Matt Duffie, though Hansen might be reluctant to pitch him in for an international debut, while utility value players such as Damian Mckenzie and Anton Lienert-Brown could also plug a hole if need be.

The All Blacks have won 10 consecutive tests against France since they lost to them 27-22 at Carisbrook in 2009.