Hello Silvio,

Slivio wrote;
> Bob I don't have sure if the black abdomen is viruses disease, but if it
was
> other agent, bacteria, fungal or protozoal I would see in the microscope.
I
> saw the black abdomen principally in high infested colonies.

But if I understand the above you did see the black abdomen in a few
colonies with low infestation?

 And many other
> colonies presented sacbrood in so high level that some colonies perished.
In
> scabrood you can see black larvas. Will be that the pupa are affected too?

Sacbrood is never a big issue in my colonies and at a level to kill hives .
I never see sacbrood with a black abdomen. Maybe others will comment. It
would seem the sacbrood larva is being affected also.

I still believe you *might* be  looking at a noninfectious disorder which
would not show up under a microscope. Example of noninfectious  disorder:

"Noninfectious disorders can be the result of neglect, lethal genes, pollen
or nectar from poisonous
plants, toxic chemicals (pesticides) or other causes. "
 Above  quote is from page 1111 of the 92 edition of the "Hive and the Honey
Bee" :

An outlaw beekeeper from South Missouri told me when I called and told him
about the problem for you to quit treating varroa with sheep dip and the
black abdomens will go away. I do not know about the use of illegal (in the
U,S.) methods but thought I would pass on the information he provided.
  He thought the black abdomens were coming under the noninfectious
disorders heading above (toxic chemicals pesticides).

Hope I have helped.

Sincerely,
Bob Harrison