Acute <3 weeks

Subacute 3-8 weeks

Chronic > 8 weeks

Significant colony count in BAL

Significant colony count in bal should be greater than 10,000 cfu/ml, whereas in urine it is greater than 10(5) cfu/ml

Fever of unknown origin

 Fever of Unknown origin[FUO] is now defined as 

1. Fever >= 38.3°C (>101°F) on at least two occasions.

2. Illness duration of more than or equal to 3weeks.

3.No known immunocompromised state.

4. Diagnosis that remain uncertain after thorough history taking , physical examination, and the following obligatory investigations:

 ESR, C reactive protein (CRP) ;

platelet count; leukocyte count and differential; hemoglobin, 

electrolytes, creatinine, 

total protein, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase,

 lactate dehydrogenase, creatine kinase,

 ferritin, antinuclear antibodies, and rheumatoid factor; 

protein electrophoresis; urinalysis;

 blood cultures (n = 3); urine culture; 

chest x-ray; abdominal ultrasonography; and

 tuberculin skin test (TST) or interferon γ release assay (IGRA).

Reference: Harrison