Is there any saying or idiom to describe the opposite of “blessing in disguise”?

Something that looks like a good thing at first, but has unforeseen bad consequences.

For instance, while irrigation schemes provide people with water for agriculture, they can increase waterborne diseases that have devastating health effects, such as schistosomiasis. (From wikipedia)

_{Major edit in body to provide a better example as requested in the comments. Saeid, please let us know if you disagree and this conflicts with your intent. -T.R.}

In certain contexts, a poisoned chalice works.

An assignment, award, or honour which is likely to prove a disadvantage or source of problems to the recipient: "many thought the new minister had been handed a poisoned chalice" (http://www.oxforddictionaries.com/definition/english/poisoned-chalice)

When something is a curse in disguise (in the disguise of a blessing), you can also simply say that something is more of a curse than a blessing.

A 'curse in disguise' is the literal opposite, and isn't unheard-of. As in:

• King Midas' gift of turning everything he touched to gold was a curse in disguise.

The phrase be careful what you wish for also comes to mind _{(Usingenglish.com)}

If you get things that you desire, there may be unforeseen and unpleasant consequences. ('Be careful what you wish for, lest it come true.' and 'Be careful what you wish for; you may receive it.' are also used.)

Also see, this wikipedia entry on unintended consequences:

Unexpected drawback: A negative, unexpected detriment occurring in addition to the desired effect of the policy (e.g., while irrigation schemes provide people with water for agriculture, they can increase waterborne diseases that have devastating health effects, such as schistosomiasis).

... In CIA jargon, "blowback" describes the unintended, undesirable consequences of covert operations,

Blowback seems to fit

chiefly US The unintended adverse results of a political action or situation:

PS - I can't remember where, but I've seen the phrase Monkey's Paw used for this. A reference to the WW Jacobs short story, in which supposedly good things happen with disastrous causes behind them.