Hmmm... odd one because it's most likely a case by case basis but if a lot of players are withdrawing with 'viral illness' then that's cause for concern if it's the same one but we have no way of telling what it is...
It's rough though, it's possible for a lot of players to catch a similar virus if they're not extremely careful...
World number two Serena Williams has hit out at the WTA Tour's injury policy, commenting that players would be fined for pulling out of a tournament even if they were dead.
Serena Williams of the US hits a return against Patty Schnyder of Switzerland at WTA Rome REUTERS - 0
* Nadal: 'Too many matches' on tour
* Gasquet in cocaine shock
The American 10-times Grand Slam winner was asked why she played at last month's Andalucia Tennis Championships when she had clearly not recovered from a thigh problem that hampered her in the final of the Sony Ericsson Open the previous week.
"Unfortunately it doesn't matter if you're injured, if you're dead or if you're alive, if you don't play they're going to fine you heavily," Williams said at a news conference ahead of this week's Madrid Open.
"So I have to play whether I am injured or not. That's just how it is so I have no choice."
Williams suffered a shock defeat to Klara Zakopalova of the Czech Republic in the first round in Marbella having lost heavily to Belarussian teenager Victoria Azarenka in Miami.
The WTA introduced a new Roadmap for 2009 designed to reduce the number of tournaments and shorten the season to make it less physically demanding on the players.
Top 10 players must still compete in at least 10 of the 20 Premier events - previously known as Tier 1 and 2 tournaments - and the four grand slams and are also obliged to play the events at Indian Wells, Miami, Madrid and Beijing.
Justine Henin's retirement last year at the age of 25 highlighted the problem of burnout and Russia's Maria Sharapova has accused the ruling body of women's tennis of being ignorant of the players' needs.
Men's world number one Rafael Nadal has repeatedly complained about the congested ATP calendar and reiterated his concerns on Saturday in Madrid at the combined men's and women's clay event.
"It's a fact that there are too many matches but that's the way the calendar has been set," the Spaniard, who suffered a knee injury at the end of last season.