Elevated acute phase reactants such as erythrocyte sedimentation rate, C-reactive protein, and prolonged P-R interval are minor laboratory criteria for rheumatic fever. Essential criteria include evidence of a prior streptococcal infection, such as a positive throat culture for streptococci, elevated streptococcal antibody titers, or presence of scarlet fever residuals. During an acute phase response in rheumatic fever, the liver produces acute phase proteins that can be detected in the blood and indicate inflammation.

1. RHEUMATIC FEVER
[ LABORATORY MANIFESTATIONS ]
SITI MARIAM BINTI MOHD HAMZAH

2. Minor criteria:
Clinical & Laboratory features
 ELEVATED ACUTE PHASE REACTANTS:
 ERYTHROCYTE SEDIMENTATION RATE
 C-REACTIVE PROTEIN
 PROLONGED P-R INTERVAL

3. ESSENTIAL CRITERIA
this refers to supporting evidence of antecedent streptococcal infection,
NOT for diagnosing ARF
• Positive throat culture for streptococci
• Streptococcal serum antibody tests
• Presence of residua of scarlet fever

4. ACUTE PHASE IN RHEUMATIC FEVER
 Acute phase develop in a small proportion of individuals several
weeks after a streptococcal infection of the throat.
 ACUTE PHASE RESPONSE is a major pathophysiological
phenomenon which accompanies inflammation resulting from
tissue damage. (etiopathogenesis)
 ACUTE PHASE REACTANTS get altered both in acute and chronic
inflammation.

6. Streptococcal
proteins display
molecular mimicry
recognized by the
immune system;
bacterial M-proteins
& human cardiac
antigens
T-cells that are
responsive to
streptococcal M-
protein infiltrate
the valve through
valvular
endothelium,
activated by the
binding
antistreptococcal
carbohydrates
with release of
TNF and IL
INFLAMMATION

7. 1.
LABORATORY FEATURES

8. ELEVATED ERYTHROCYTE SEDIMENTATION
RATE (ESR)
• Normal value
• 10 mm/hour in men
• 20 mm/hour in women
• In rheumatic fever,
• At least 60 mm/hour in low-risk
populations
• At least 30 mm/hour in high-risk
populations
• Rise in ESR suggests
inflammatory processes. In
many cases, the level of ESR
may reflect the severity of the
inflammatory process.

9. ELEVATED C-REACTIVE PROTEIN (CRP)
• CRP is a beta-globulin present in serum, capable of
reacting with the outer coat of pneumococci.
• Normally it is absent from human plasma. When
inflammatory processes occur, the liver produces
an identical protein which can be detected by a
slide test using readymade reagents.
• CRP level in rheumatic fever, is at least 3.0 mg/dl

10. PROLONGED P-R INTERVAL
• P-R interval is a measure of the atrioventricular (AV)
conduction. Prolonged PR interval indicates AV block.
• Normal PR interval is 0.12 to 0.20 sec, slightly shorter
in children with upper limit being 0.18 sec.
• In case of rheumatic fever, it is due to the
inflammation of the myocardium that caused delay
in the AV conduction, thus prolonged PR interval.

11. 2.
ESSENTIAL CRITERIA

12. POSITIVE THROAT CULTURE FOR STREPTOCOCCI
 The gold standard for detecting Streptococcus pyogenes
remains a throat swab cultured on blood agar.
 If possible, throat swabs should be examined for all
patients with clinically suspected streptococcal upper
respiratory tract infection.

13. STREPTOCOCCAL SERUM ANTIBODY TESTS
 The most commonly performed and commercially available
tests are the antistreptolysin-O test, and the
antideoxyribonuclease-B test.
 At least one anti-streptococcal antibody titre should be
elevated for a diagnosis of acute RF.
 Although a single elevated antibody titre may be useful for
documenting a previous streptococcal infection, it is recommended
that an additional test be performed 3–4 weeks after the onset of RF.
Rising titer of antibody is a stronger evidence for a recent
streptococcal infection.

14. http://www.who.int/cardiovascular_diseases/resources/en/cvd_trs923.pdf
A serum antibody is judged to be elevated if the titre exceeds the
upper limit of the normal titre range

15. PRESENCE OF RESIDUA OF SCARLET FEVER
 The desquamation of skin of palms and soles indicates
that the patient has had scarlet fever within the previous
2 weeks. Scarlet fever is rare in India.
an infectious bacterial
disease affecting especially
children, and causing fever
and a scarlet rash. It is
caused by streptococci.

16. THANK YOU