hi..from the history mentioned it looks like your husband may have contracted a viral fever
. viral fevers are known to cause decreased platelet counts and also white blood cell
counts..they are usually self limiting. and for breathing difficulty, it looks like your husband might have developed pleural effusion
or minimal pulmonary edema
. the fluid usually gradually resolves most of the times.
and for dengue
part, the test for detecting usually isnt positive all the time, and hence negative result doesnot rule it out. also, we have to consider the possibility of rose virus infection. the treatment of dengue and viral fevers is supportive, and to prevent and manage bleeding episodes, which your husband has not had, which is a good sign.