ASLO Titres are used in the diagnosis of ?
**Core Concept**
Antistreptolysin O (ASLO) titres are a measure of the body's immune response to Group A beta-haemolytic streptococci (GABHS) infection. The ASLO test detects the presence of antibodies against streptolysin O, a toxin produced by GABHS.
**Why the Correct Answer is Right**
The ASLO test is used to diagnose recent or past streptococcal infections, such as pharyngitis or skin infections. Elevated ASLO titres indicate a current or recent infection with GABHS, while declining titres suggest that the infection is resolving. The ASLO test is particularly useful in differentiating streptococcal from viral pharyngitis.
**Why Each Wrong Option is Incorrect**
**Option A:** The Widal test is used to diagnose typhoid fever, not streptococcal infections.
**Option B:** The VDRL test is used to screen for syphilis, not streptococcal infections.
**Option C:** The CRP test is a non-specific marker of inflammation, not a specific test for streptococcal infections.
**Clinical Pearl / High-Yield Fact**
Remember that ASLO titres typically rise 1-2 weeks after the onset of streptococcal infection and remain elevated for several weeks. This knowledge can help guide the timing of the ASLO test in patients with suspected streptococcal infections.
**Correct Answer: D. Rheumatic fever.**