Q: My father is having mild fever for last four weeks. We have done following tests.1. tc, dc,esr,hg all normal(esr 10) 2.urine normal 3.chest x ray normal 4.abdomen scanning normal 5.blood urea normal6.urine culture growth- klabsiella 7.blood for malaria no malaria parasite found 8.ECG normal. Before going for tests he was given amoxycillin for five days.After urine culture was done, he was givenchloromycetin 250 X 4 for 5 days.currently we are giving him only vitamin supplements.my father is 80 years old and does not suffer from any other disease.he has normal appetite.he broke his left leg 20 years back in a bus accident and because of that he has some pain in that leg.recently about 3 months back he complained loss of strength in his legs and the doctor felt he is suffering from neuropathy for which he is taking 3 tabs of mazetol everyday with vitamin supplements and nutrients and he is feeling improvement.during the day he always has a temperature of 98,98.9,99,99.8,98.4,98.2.Can u suggest what could be the reason of this fever?

A:Fever of unknown cause of such duration is called pyrexia of undetermined cause, or PUO for short. Such cases are usually investigated in hospital and sometimes they test the best! Your father will need to be investigated by a physician in hospital where clinical assessments can be done every day and investigations can be performed as necessary. I can only make some general comments which, I hope, will behelpful.First, malaria cannot be ruled out on a single blood smear; repeated thickand thin smears will need to be done to make sure that it is not missed.Second, one has to consider a subacute infection such as typhoid, brucella,TB and infective endocarditis. Typhoid is unlikely since the temperaturetouches the baseline but brucella and TB will need to be explored. Inparticular a CT scan of the chest and abdomen may be useful in detecting anyglandular enlargement. This test will also reveal glandular enlargement of alymphoma which is also a cause of a PUO. A bone marrow smear might beuseful for malaria, TB or any infiltrative disorder. If all investigationsare negative and TB is still considered a possibility then a therapeutictrial may be undertaken.Finally, there are a number of collagen disorders which may cause PUO. Ifno cause is found and the fever continues, but does not cause anytroublesome symptoms, then one may watch and be ready to do moreinvestigations if any othe clue appears.These problems are not easy to crack. I hope a cause is found soon and yourfather is restored to good health.