1) Acute rheumatic fever is an autoimmune disease that can develop as a complication of untreated strep throat. It mainly affects children aged 5-14 and can cause inflammation of the heart, joints, brain, and skin.
2) The presentation and diagnosis is based on revised Jones criteria which looks for evidence of preceding strep infection and manifestations involving two major criteria or one major and two minor criteria.
3) Treatment involves antibiotics to treat the initial strep infection, anti-inflammatory drugs, and long-term antibiotics to prevent recurrent attacks which can further damage the heart valves and lead to rheumatic heart disease.
1. ADAMA HOSPITAL MEDICAL COLLEGE
Department Of Internal Medicine
Seminar on Acute Rheumatic Fever
Presenter: Dr Rebil Heiru (R1)
Moderator: Dr Demu Tesfaye (Assistant professor and Consultant
Internist)
28/6/2011 E.C.
4. Introduction
⢠Acute rheumatic fever (ARF) is a multisystem disease resulting from
an autoimmune reaction to infection with group A streptococcus.
⢠Although many parts of the body may be affected, almost all of the
manifestations resolve completely.
⢠The exception is cardiac valvular damage [rheumatic heart disease
(RHD)], which may persist after the other features have disappeared.
5. IntroductionâŚ
⢠ARF and RHD are diseases of poverty.
⢠It has been estimated that between 15 and 19 million people worldwide
are affected by RHD, with approximately one-quarter of a million
deaths occurring each year.
⢠Some 95% of ARF cases and RHD deaths now occur in developing
countries.
6. IntroductionâŚ
⢠Although ARF and RHD are
relatively common in all
developing countries, they
occur at particularly elevated
rates in certain regions.
⢠These "hot spots" are
ďźsub-Saharan Africa,
ďźPacific nations,
ďźAustralasia, and
ďźthe Indian
subcontinent
7. Epidemiology
⢠ARF is mainly a disease of children aged 5â14
years.
⢠Initial episodes become less common in older
adolescents and young adults and are rare in
persons aged >30 years.
⢠Recurrent episodes of ARF remain relatively
common in adolescents and young adults.
8. EpidemiologyâŚ
⢠This pattern contrasts with the prevalence of RHD, which peaks
between 25 and 40 years.
⢠There is no clear gender association for ARF, but RHD more
commonly affects females, sometimes up to twice as frequently as
males.
9. Epidemiology
⢠The mean incidence of ARF is 19 per 100,000 school-aged
children worldwide.
⢠Auscultation-based surveys in Ethiopia conducted in the
late 1990's reported a rural prevalence of 4.6/1000 and an
urban prevalence of 6.4/1000 of rheumatic heart disease
(RHD).
⢠With echo-based screening yielding a prevalence of 19
[13.9-23.4, 95% CI] cases per 1000 school children
between the ages of 6-18years.
10. Pathogenesis
⢠Based on currently available evidence, ARF is exclusively
caused by infection of the upper respiratory tract with group
A streptococci
⢠Classically, certain M-serotypes (particularly types 1, 3, 5, 6, 14,
18, 19, 24, 27, and 29) were associated with ARF
(âRheumatogenicâ)
⢠In high-incidence regions any strain of group A streptococcus has
the potential to cause ARF.
11.
12.
13.
14.
15. Do GAS skin infections (pyoderma/ impetigo)
cause ARF?
17. Can some GAS strains cause both acute post
streptococcal glomerulonephritis (APSGN) and ARF?
18. Pathogenesis
Genetic Susceptibility
⢠It is likely that 3â6% of people in any population have an
inherent susceptibility to ARF, although the basis of this
susceptibility is unknown
⢠And this proportion does not vary dramatically between
populations.
⢠Findings of familial clustering of cases and concordance in
monozygotic twinsâparticularly for choreaâconfirm that
susceptibility to ARF is an inherited characteristic
20. Pathogenesis
⢠Historically there have been three major categories of hypotheses
1. Direct infection (for example, by the group A streptococcus);
2. Effects of a streptococcal toxin (streptolysin O has been among the most
commonly discussed); and
3. Most feasibly, the concept of antigenic mimicry in association with an
abnormal immune response.
⢠During the past half century, it is the concept of antigenic mimicry
and/or an abnormal immune response to group A streptococcal
extracellular or somatic antigens which has been most interesting
21. Pathogenesis
⢠When a susceptible host encounters a group A streptococcus, an
autoimmune reaction results, which leads to damage to human tissues
as a result of cross-reactivity between epitopes on the organism and the
host
⢠Cross-reactive epitopes are present in the streptococcal M
protein and the N-acetylglucosamine of group A streptococcal
carbohydrate and are immunologically similar to molecules in
human myosin, tropomyosin, keratin, actin, laminin, vimentin,
and N-acetylglucosamine.
22.
23.
24. Pathogenesis
⢠It is currently thought that the initial damage is due to cross-reactive
antibodies attaching at the cardiac valve endothelium
⢠allowing the entry of primed CD4+ T cells, leading to subsequent T
cell-mediated inflammation
⢠The only recognised natural host (and reservoir) for group A
streptococci is the human, and an appropriate animal model
has not been identified in half a century
25. Pathologic lesions
⢠Aschoff bodies-fibrinoid degeneration of connective tissue,
inflammatory edema, inflammatory cell infiltration and proliferation of
specific cell results in nodule formation.
⢠Resulting in:
ďPancarditis in the heart
ďArthritis in the joints
ďAshcoff nodules in the subcutaneous tissue
ďBasal gangliar lesions resulting in chorea
26. Unanswered questions
1. Why is Mitral valve (and aortic
valve) preferred if it is true
antigen mimicry?
2. Why does one present with
arthritis while another develop
carditis�
3. Why does one patient with
rheumatic carditis develop RHD
while another do not?
27. Clinical Features
⢠There is a latent period of ~3 weeks (1â5 weeks) between the
precipitating GAS infection and the appearance of the clinical
features of ARF.
⢠The exceptions are chorea and indolent carditis, which may
follow prolonged latent periods lasting up to 6 months.
28. Clinical Features
ď§ Carditis and valvulitis (eg, pancarditis) that is clinical or subclinical â 50 to
70 percent
ď§ Arthritis (usually migratory polyarthritis predominantly involving the large
joints) â 35 to 66 percent
ď§ Central nervous system involvement (eg, Sydenham chorea) â 10 to 30 percent
ď§ Subcutaneous nodules â 0 to 10 percent
ď§ Erythema marginatum â <6 percent
29. Clinical FeaturesâŚArthritis
⢠The typical arthritis is migratory, moving from one joint to
another over a period of hours.
⢠ARF almost always affects the large jointsâmost commonly
the knees, ankles, hips, and elbowsâand is asymmetric.
⢠The pain is severe and usually disabling until anti-
inflammatory medication is commenced.
30. Clinical FeaturesâŚArthritis
ď§Arthralgia without objective joint inflammation usually affects
large joints in the same migratory pattern as polyarthritis.
ď§In some populations, aseptic monoarthritis may be a presenting
feature of ARF.
ď§This may occur because of early commencement of anti-
inflammatory medication before the typical migratory pattern is
established.
31. Clinical FeaturesâŚArthritis
⢠The joint manifestations of ARF are highly responsive to
salicylates and other nonsteroidal anti-inflammatory drugs
(NSAIDs).
⢠Indeed, joint involvement that persists more than 1 or 2 days
after starting salicylates is unlikely to be due to ARF.
⢠Synovial fluid analysis shows sterile inflammatory fluid.
⢠There is absence of long-term joint deformity.
32. Carditis
⢠The only manifestation which leave sequela and permanent damage to the
organ.
⢠Presents in 50-70% of cases.
⢠Valvular damage is the hallmark of rheumatic carditis.
⢠For asymptomatic patients it can be diagnosed with echocardiography.
⢠Echocardiography screening of school aged children in population with
high incidence of RHD is becoming more widespread.
33. ⢠Mitral valve is most often affected with RHD(75-80%), followed by
mitral and aortic together, then aortic alone(30%), then mitral, aortic,
and tricuspid together.
⢠Damage to the pulmonary or tricuspid valves is usually secondary to
increased pulmonary pressures resulting from left-sided valvular
disease (5%).
34. In acute phase
ď§ Valvulitis occur which leads to regurgitation.
ď§ MR : a high-pitched apical holosystolic murmur radiating to
the axilla
ď§ The Carey Coombs murmur, a short mid-diastolic murmur heard
loudest at the apex, is an indicator of moderate-severe MR as a result
of increased blood flow across the mitral valve during left ventricular
filling.
ď§ AR : a high-pitched decrescendo diastolic murmur at the upper
left sternal border
35. ⢠CHF due to severe MR/AR
⢠ECG-any degree heart block,
⢠chest xray-cardiomegaly
⢠Echocardiography-valve lesion
-pericardial effusion
-ventricular/atrial dilation
36. IN Chronic phase
ďśOver several years, usually as a result of recurrent episodes,
ďźleaflet thickening
ďźfibrosis
ďźscarring
ďźcalcification, and valvular stenosis develop
ďśValvular stenosis: appears several years or even decades after the
acute illness
ďśHowever, in developing countries where ARF often occurs at
earlier age, MS & AS may develop in young children
37. ďśModerate to severe rheumatic carditis: new heart
murmur, cardiomegaly & CHF with hepatomegaly &
peripheral & pulmonary edema and perciardial friction rub
ďśMyocarditis &/or pericarditis without evidence of
endocarditis: rarely due to RHD
42. Subclinical carditis
⢠Refers exclusively to the circumstance in which classic
auscultatory findings of valvulvar dysfunction either
are not present or are not recognized by the diagnosing
clinician but echocardiography/Doppler studies reveal
mitral or aortic valvulitis.
43. Sydenham chorea
⢠Incidence 10-30%,found mainly in females
⢠(also known as chorea minor or "St. Vitus dance")
⢠is a neurologic disorder consisting of purposeless, non rhythmic
involuntary movements, muscular weakness, and emotional
disturbances.
⢠Antibodies directed to GAS cross react with lysogangloside which
trigger signals.
⢠The chorieform movement affects mainly the head causing darting
movement of the tongue and upper limbs.
44. Clinical manifestation
⢠5-13 yrs, female(2x more common)
⢠Onset 1-8 month after pharyngitis
⢠Emotional changes precede(easy crying/in appropriate laughing)
⢠Usually generalized, unilateral in 20-30%
⢠Loss of fine motor, muscle weakness,hypotonia
⢠Psychiatric symptoms-irritability,outburst behavior
(crying,laughing)
⢠Cease during sleep.
45. ďśClinical maneuvers to elicit features of chorea include
(1) demonstration of milkmaid's grip (irregular contractions of
the muscles of the hands while squeezing the examiner's fingers)
(2) spooning and pronation of the hands when the patient's arms
are extended
(3) wormian darting movements of the tongue upon protrusion
(4) examination of handwriting to evaluate fine motor movements
46. Diagnosis
⢠Clinically-with supportive evidence of GAS antibodies
but may not be there.
⢠Chorea with carditis is confirmatory
⢠May not have other clinical symptoms but should
undergo echocardiography screening.
47.
48. Subcutaneous Nodules
⢠Incidence 0-10%
⢠Firm, painless, symmetric, mobile, small(0.5- 2 cm) lumps at bony prominence
or extensor surface of near tendon.
⢠There is a correlation between the presence of these nodules and
significant rheumatic heart disease
⢠Smaller and short lived nodules than rheumatoid arthritis.
⢠Elbows are mostly involved, in that rheumatic fever on olecranon while in
rheumatoid arthritis 3-4 cm distally.
49.
50. Erythema Marginatum
⢠Incidence <6%
⢠begins as pink macules that clear centrally, leaving a serpiginous,
spreading edge.
⢠Erythema marginatum is an evanescent, pink or faintly red,
non-pruritic rash involving the trunk and sometimes the limbs
but not on the face.
⢠Heat can induce its appearance, and it blanches with pressure
52. Other features
⢠Fever >38.50c, but for moderate-high risk areas 380c can be
considered.
⢠Elevated acute phase reactant(CRP and ESR)
⢠ECG-prolonged PR interval
53. Late sequelae
⢠RHD is the most common cause of valvular disease among the
world.
⢠Occurs 10-20 yrs after original illness
⢠Mitral valve is commonly involved than aortic valve.
⢠MS caused by severe mitral calcification, is the classical finding
of rheumatic heart disease.
⢠Occurs in 50% of carditis at initial presentation.
54. Late sequelae
⢠Jaccoud arthropathy â Jaccoud arthropathy is a benign,
chronic arthropathy that involves loosening and lengthening of
periarticular structures and tendons in the hands and/or feet
⢠The deformities are painless, "correctable" with manipulation,
and do not cause functional impairment.
⢠The arthropathy is not associated with active joint
inflammation.
56. Evidence of a preceding Group A
Streptococcal infection
Streptococcal pharyngitis diagnosed by
ďPositive throat culture for group A beta-hemolytic streptococci
ďPositive rapid streptococcal antigen test
ďElevated or rising antistreptolysin O antibody titer (ASO titer)
or other streptococcal antibody(anti-DNAase)
57. Throat culture
ďśThroat culture remains the
diagnostic gold standard.
ďśCulture of a throat specimen that is
properly collected and properly
processed is the most sensitive and
specific means of definitive
diagnosis.
ďśSensitivity 90%, specificity 99%
58. Rapid streptococcal antigen test
⢠A very rapid test, used to early
detection of streptococcal
pharyngitis.
⢠Usually negative during clinical
appearance of rheumatic fever.
59. Streptococcal Antibody Tests
ďśASO titer âfor children 300todd unit
-for adult-250todd unit
-elevated in 80% of ARF
ďś Begin to rise 1 wk, peaks 3-6 wks
ďśSingle antibody measured: 80-85% of patients
have an elevated titer
ďśIf 3 different antibodies (antistreptolysin O, anti-
DNase B, antihyaluronidase) measured: 95-100%
have an elevation
63. âPossibleâ Rheumatic Fever
1.Where there is genuine uncertainty, it is reasonable to
consider offering 12 months of secondary prophylaxis
⢠followed by reevaluation to include a careful history and
physical examination in addition to a repeat
echocardiography
64. 2.In a patient with recurrent symptoms (particularly involving the
joints) who has been adherent to prophylaxis recommendations
⢠but lacks serological evidence of GAS infection and lacks
echocardiographic evidence of valvulitis,
⢠it is reasonable to conclude that the recurrent symptoms are not
likely related to ARF, and discontinuation of antibiotic
prophylaxis may be appropriate echocardiogram
65. Treatment
⢠Step I - primary prevention (eradication of streptococci)
⢠Step II - anti inflammatory treatment (aspirin, steroids)
⢠Step III- supportive management & management of
complications
⢠Step IV- secondary prevention(prevention of recurrent
attacks)
⢠Step V -follow up
65
66. Step I - primary prevention
ďprimary prophylaxis (the timely and complete treatment of
group A streptococcal sore throat with antibiotics)
ďIf commenced with in 9 days of sore throat onset a course of
penicillin will prevent all cases of ARF
ďIdeally, primary prevention would entail elimination of the
major risk factors for streptococcal infection, particularly
overcrowded housing.
68. Step II - anti inflammatory treatment
ďBed rest and indoor ambulation
ďRecommended anti-inflammatory agents
_______________________________________________________________________________________
Arthritis Mild Moderate Severe
alone carditis carditis carditis
__________________________________________________
Prednisone 0 0 0 2-6 wk*
Aspirin 1-2 wk 3-4 wk# 6-8 wk 2-4 mo
___________________________________________________
⢠Prednisone should be tapered after 2-3 wks and aspirin started during the tapering Aspirin
may be reduced to 60 mg/kg/day
⢠Aspirin(80 to 100 mg/kg per day in children and 4 to 8 g/day in adults)
69. ⢠Naproxen has a superior side-effect profile to aspirin and can be dosed
twice daily.
⢠A single, small, open-label, randomized study found that naproxen
had similar efficacy to aspirin with regard to time until resolution of
arthritis but was safer and easier to use.
⢠Naproxen is dosed at 10 to 20 mg/kg/day in divided doses BID to a
maximum of 1000 mg/day in children aged over two years and 250 to
500 mg BID to a maximum of 1250 mg in adults.
70. Treatment of chorea
⢠Most patients with SC recover fully without treatment
⢠mild- keeping patient in a calm environment
⢠significant impairment of motor function
1. Haloperidol (0.01-0.03 mg/kg/day divided bid PO) 3-4 mo.
2. Corticosteroids ( Prednisolone 1-2 mg/kg daily for 2 wks then
tapered over 2-3 wks)
⢠Treatment with either valproic acid or carbamazepine is a reasonable
alternative
⢠chronic treatment with prophylactic antibiotics.
71. Step III- supportive management & management of
complications
⢠Treatment of congestion
⢠General measures
⢠Diuretics
⢠Surgical management
72. Step IV- secondary prevention
⢠Patients with ARF should take long term penicillin to
prevent recurrence.
The risk of recurrent rheumatic fever depends
ďThe number of previous attacks
ďTime since the last attack
ďRisk of exposure to the streptococcal infections
ďPatient age
ďPresence or absence of cardiac involvement
75. Prognosis
⢠Untreated ARF lasts 12 wks
⢠With treatment patient discharged from hospital after 1-2 wks
⢠Inflammatory markers should be followed every 1-2 wks
until they normalized(usually with 4-6 wks)
⢠Echocardiography after 1 month
77. Take home message
⢠Acute rheumatic fever remains a serious healthcare concern for the
majority of the worldâs population, especially for developing countries.
⢠It causes significant disability, loss of quality of life and length of life
and costs to individuals, their families and to society
⢠RHD is the only truly preventable chronic heart condition
⢠Appropriate treatment of group A strep pharyngitis necessary to
prevent disease.
⢠Preventing recurrences causing chronic heart disease simple,
universally available, and cost-effective.
78. REFERENCES
⢠Kasper, Hauser, Longo, Jameson, Loscalzo Harrisonâs principles of
Internal Medicine 19th Edition Copyright Š 2015 by McGraw-Hill
Education
⢠Newzealand guideline for acute rheumatic fever 2014
⢠UptoDate version 21.8
80. Thank you!
âHe korokoro ora he manawa ora
Mo tatou katoaâ
A healthy throat, a healthy heart for us all
Editor's Notes
* Classic teaching states that only upper respiratory tract infection with GAS has the potential to cause ARF. However, there is circumstantial
evidence that in certain populations (e.g. Aboriginal people), GAS skin infections may play a role in ARF pathogenesis
Whether there is a causal link between skin streptococcal infections and ARF has been debated. Key
studies are detailed in Appendix 8 and referred to in the following questions.
Recent research from Australia suggests a possible link between skin streptococcal infections and
rheumatic fever.22 McDonald et al hypothesised that recurrent skin infections may immunise against
throat colonisation and infection,22 although this link has not been proven.7
Despite the high incidence in some ethnic groups (such as MÄori and Pacific people in New Zealand), a genetic
predisposition to ARF remains unproven.
The issue was concisely summarised in a recent review by Cunningham who commented: ââThe disease is autoimmune in
nature and most likely results in part from the production of autoreactive antibodies.ââ7 Yet, although many candidate group A streptococcal
antigenic moieties have been investigated, none has been unequivocally demonstrated to be the inciting ââculpritââ or to fully explain the disease
process.
7 Cunningham MW. Pathogenesis of group A streptococcal infections. Clin
Microbiol Rev 2000;13:470â511.
Multiple attempts to strengthen the available data explaining a streptococcal pathogenesis by identifying a specific
animal model for the study of rheumatic fever and rheumatic heart disease have not been entirely successful. Numerous
group A streptococcal somatic and extracellular antigens have been injected into multiple animal species and almost
always have resulted in lesions, but none of the models have the combined clinical or pathologic features of rheumatic
fever/rheumatic heart disease. The only recognised natural host (and reservoir) for group A streptococci is the human,
and an appropriate animal model has not been identified in half a century. Thus, laboratory efforts to define a comprehensive
concept of streptococcal rheumatogenecity have been severely hampered
* Embryologists remind us that all four valves develop from the same embryonic cell rest. If true antigenic mimicry involving heart valve tissue is
responsible, would one not expect random involvement of and damage to all four heart valves in a random fashion?
People with RHD are often asymptomatic for many years before their valvular disease progresses to cause cardiac failure. Moreover, particularly in resource-poor settings, the diagnosis of ARF is often not made, so children, adolescents, and young adults may have RHD but not know it. These cases can be diagnosed using echocardiography; auscultation is poorly sensitive and specific for RHD diagnosis in asymptomatic patients. Echocardiographic screening of school-aged children in populations with high rates of RHD is becoming more widespread and has been facilitated by improving technologies in portable echocardiography and the availability of consensus guidelines for the diagnosis of RHD on echocardiography. Although a diagnosis of definite RHD on screening echocardiography should lead to commencement of secondary prophylaxis, the clinical significance of borderline RHD has yet to be determined
(fishmouth valves).
* AMVL thickness should be measured during diastole at full excursion. Measurement should be taken at the thickest portion of the leaflet, including focal thickening, beading, and nodularity. Measurement should be performed on a frame with maximal separation of chordae from the leaflet tissue. Valve thickness can only be assessed if the images were acquired at optimal gain settings without harmonics and with a frequency âĽ2.0 MHz.Âś Abnormal thickening of the AMVL is age-specific and defined as follows: âĽ3 mm for individuals aged â¤20 years; âĽ4 mm for individuals aged 21 to 40 years; âĽ5 mm for individuals aged >40 years. Valve thickness measurements obtained using harmonic imaging should be cautiously interpreted and a thickness up to 4 mm should be considered normal in those aged â¤20 years.Î Restricted leaflet motion of either the anterior or the posterior MV leaflet is usually the result of chordal shortening or fusion, commissural fusion, or leaflet thickening.â Excessive leaflet tip motion is the result of elongation of the primary chords, and is defined as displacement of the tip or edge of an involved leaflet towards the left atrium resulting in abnormal coaptation and regurgitation. Excessive leaflet tip motion does not need to meet the standard echocardiographic definition of MV prolapse disease, as that refers to a different disease process. This feature applies to only those aged <35 years. In the presence of a flail MV leaflet in the young (â¤20 years), this single morphological feature is sufficient to meet the morphological criteria for RHD (that is, where the criteria state "at least two morphological features of RHD of the MV," a flail leaflet in a person aged â¤20 years is sufficient).§ In the parasternal short axis view, the right and noncoronary aortic cusp closure line often appears echogenic (thickened) in healthy individuals and this should be considered as normal.
(A) Ulnar deviation, metacarpophalangeal subluxation, and swan-neck deformities are present. There is also diffuse soft-tissue swelling.
(B) A radiograph shows the deformities, but there is no true joint space narrowing or erosion, which would be expected in a patient with rheumatoid arthritis with similar hand deformities. This type of deformity in systemic lupus erythematosus is reducible and is caused by tendon laxity, rather than bony destruction, and may also be seen in post-rheumatic fever arthritis.
Acute rheumatic fever typically develops 2-4Â wk after an acute episode of GABHS pharyngitis at a time when clinical findings of pharyngitis are no longer present & only 10-20% of the throat culture or rapid streptococcal antigen test results are positive
The throat culture remains the diagnostic gold standard. Culture of a throat specimen that is properly collected (i.e., by vigorous rubbing of a sterile swab over both tonsillar pillars) and properly processed is the most sensitive and specific means of definitive diagnosis. A rapid diagnostic kit for latex agglutination or enzyme immunoassay of swab specimens is a useful adjunct to throat
culture. While precise figures on sensitivity and specificity vary, rapid diagnostic kits generally are >95% specific. Thus a positive result can be relied upon for definitive diagnosis and eliminates the need for throat culture. However, because rapid diagnostic tests are less sensitive than throat culture (relative sensitivity in comparative studies, 55â90%), a negative result should be confirmed by throat culture.
Anti-streptolysin O (ASO)titre:For these reasons, it may be useful to collect one specimen when the diagnosis of ARF is first suspected and another two weeks later.
Anti-streptolysin O (ASO) titers vary with age, season, and geography [ 22 ]. Healthy children of elementary school age commonly have titers of 200 to 300 Todd units per mL; asymptomatic pharyngeal strep carriers tend to have very low titers, just above detectable. Following streptococcal pharyngitis, the antibody response peaks at about four to five weeks, which usually is during the second or third week of rheumatic fever. Antibody titers fall off rapidly in the next several months and after six months have a slower decline. For these reasons, it may be useful to collect one specimen when the diagnosis of ARF is first suspected and another two weeks later.
About 80 percent of patients with documented ARF demonstrate a rise in antistreptolysin titer, although this cannot be used as a measure of rheumatic activity. A negative antistreptolysin titer should prompt testing for other antistreptococcal antibodies such as anti-DNAse B (detectable for six to nine months following infection), streptokinase, and antihyaluronidase; commercial tests for these antibodies are available. About 90 percent of patients with documented ARF have positive findings if two antigens are evaluated; about 95 percent have positive findings if three antigens are evaluated.
Acute-phase reactants are increased in ARF. Both serum C-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) are invariably elevated during the active rheumatic process unless they are suppressed by antirheumatic drugs [ 23 ]. CRP or ESR is useful for monitoring "rebounds" of inflammation as treatment is tapered. A normal result obtained a few weeks after discontinuing antirheumatic therapy suggests that the course of the illness is complete (unless chorea appears). The CRP is probably more useful since it typically normalizes over a matter of days once an episode of acute inflammation has resolved, while the ESR may stay elevated for up to two months after a transient inflammatory stimulus.
A mild normochromic normocytic anemia of chronic inflammation may be observed during acute rheumatic fever. Suppressing the inflammation usually improves the anemia; iron therapy generally is not indicated.
Complement levels are usually normal in ARF. In contrast, hypocomplementemia is typically observed in the setting of poststreptococcal glomerulonephritis.
Analysis of the synovial fluid in rheumatic fever with arthritis generally demonstrates sterile inflammatory fluid