How serious is kidney infection or pyuria? Is it contagious? Or it can be treated with pills and syrups. Does it cause sexual issue

Kidney infection. Kidney infection (pyelonephritis) generally causes fever, chills and very significant flank pain. One generally feels "sick". Bladder infection (cystitis) rarely causes systemic symptoms. Discomfort in the pelvic area and irritative voiding symptoms are typical. Neither are contagious.