[taregg (OP)]

does high  temperature increase virus in body....and how.

[yellowcat]

I don't think so. Many viruses do not replicate so well at elevated temperatures/fever is part of the immune response against viral infections.
Of course in biology things are seldom simple, thinking of avian flu, birds generally have a higher body temperature  than mammals so presumably their viruses are heat adapted.
Maybe that is why avian  flu is such a dangerous infection.