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Is This Rash Scarlet Fever-Or Not?

If misdiagnosed, scarlet fever can lead to multiple, and very serious, complications.

A 15-year-old female presented to her primary care provider with a 3-day history of a systemic, itchy rash. The patient had been informed by her school nurse that at least two confirmed cases of scarlet fever had been detected, and that she could not return to school until after the rash had subsided.

The patient, who has no known allergies, denied any previous history of rashes, but had been diagnosed and treated by her PCP 1 week prior to the onset of the rash for an upper respiratory tract infection (URI) including pharyngitis. Over-the-counter treatments used included diphenhydramine (Benadryl) and hydrocortisone cream, which provided some relief.

The patient returned to the PCP with new complaints of a sore throat and admitted to ceasing amoxicillin (Amoxil) after 3 days of therapy due to relief of symptoms. The patient admits to being around individuals with similar symptoms prior to initial treatment. No laboratory tests were performed.

Physical Examination
The physical examination showed an alert, 15-year-old female who was in no acute distress. The patient's weight was 126 lbs, height was 5'5" and BMI was 20.8. Her blood pressure was 114/62 mmHg, heart rate was 78 beats/minute, respiratory rate was 16 breaths/minute. Her temperature was 98.9° F in the office, but she reported experiencing chills and a fever of 100.9° F that broke with ibuprofen (Motrin) 400mg PRN.

Examination of the skin revealed a raised, red, papular/macular rash with a systemic diffuse pattern to the anterior and posterior trunctal area, arms, legs, and face without petechia, which blanched when pressed. She had cervical lymphadenopathy, a cobblestone appearance on the posterior aspect of her tongue, pharyngeal erythema without exudate, tonsils measured 2+ with uvula midline and without lesions, ulcerations, or growths noted. No hepatomegaly or splenomegaly was noted.  

Review of symptoms revealed that this patient has had multiple URIs over the past two years. Currently, she has a sore throat, myalgia, malaise, nausea and vomiting, with a decreased appetite for at least one month. She reported no abdominal pain except with menses.

The patient reported feeling some amount of stress due to school anxieties, her father recently leaving home and an ongoing battle with anorexia nervosa. Still, she claimed to be in good mental and physical health despite these stressors and denied using tobacco, alcohol or drugs.

She reports being sexually active and only uses condoms for protection. She began menses at age 12 and reports irregular menstrual cycles. She reports gravida-0, para-0, and abortion-0. Family history is positive for eczema, psoriasis, hypertension, diabetes and obesity.

Definition of Scarlet Fever
Scarlet fever (Scarlatina) is a syndrome characterized by a group of symptoms caused by toxin-producing, group-A beta-hemolytic streptococci (GABHS), particularly streptococcus pyogenes.

The most common places for GABHS replication are the tonsils and pharynx, thus making proper identification and treatment of strep throat imperative in the prevention of scarlet fever. According to the Centor Score for the evaluation of strep throat, criteria include:

• absence of a cough;

• swollen & tender anterior cervical lymph nodes;

• fever  > 100.40 F (380 C); and

• tonsillar swelling and/or exudate.7

Symptoms of Scarlet Fever
Note that the symptoms include fever, exudative pharyngitis, and a scarlitinaform rash.1 The toxin produced by GABHS is often referred to as erythemogenic or erythrogenic in nature, and is most commonly detected in secretions from the nose, ears, skin and throat, but can be present in any mucous membrane.

These toxins cause the pathognomonic rash as a consequence of local production of inflammatory mediators and alteration of the cutaneous cytokine milieu. This results in a sparse inflammatory response and dilatation of blood vessels, resulting in the characteristic scarlet color and the rough, sandpaper-like texture of the rash. The rash appears 1 to 4 days after the onset of fever, usually beginning on the patient's head, neck or armpits. It can then spread systemically.1,2

In addition to a sandpaper-like texture, the rash associated with scarlet fever may have petechiae, will blanch when pressed, and is more pronounced in skin folds (known as Pastia's lines). Eventually, sloughing of the skin on the palms of the hands and soles of the feet will occur.

Other associated symptoms include a bright, strawberry-red tongue, facial flushing with pallor around the mouth, sore throat, headache, nausea and vomiting, swollen tonsils with exudate, cervical or general lymphadenopathy, fever, chills, malaise, and abdominal pain. Complications are rare, but if left untreated this organism can cause heart valve complications, carditis, acute rheumatic fever, osteomyelitis, arthritis, otitis media, abscesses, glomerulonephritis, hepatitis, meningitis, pneumonia, sinusitis, and toxic shock syndrome.2

Causes of Scarlet Fever
Scarlet fever is classically associated with certain wound infections, burns, upper respiratory infections, some food-borne illness outbreaks, and streptococcal tonsillar or pharyngeal infections.4

The rash associated with scarlet fever occurs in less than 10% of  all strep throat  infections, and is most prevalent in children between the ages of 5 to 15 years; but it can affect individuals at any age.1,2

Streptococci, which are normal inhabitants of the nasopharynx, are gram-positive cocci that grow in chains that cause hemolysis on blood agar. Streptococci is able to survive extreme temperatures and humidity, thus facilitating its transfer from one host to another.

Scarlet fever can occur at any time of the year, but is most prevalent during the winter and spring months. The causative bacterium (GABHS) is commonly transmitted through airborne respiratory droplets, which are expressed by infected individuals and picked up by other individuals who have come into contact with the infected secretions. Transmission rates increase in crowded environments where individuals are in close contact to one another such as schools, day-care centers, or dormitories.

The incubation period for this disease ranges from 12 hours to 7 days, and individuals are considered contagious during the acute and subclinical stages (or for at least 24 hours after beginning antibiotic therapy).

Health care providers treating patients with scarlet fever should focus on correctly identifying the infection, beginning appropriate antibiotic therapy, teaching patients and family members about proper hand-washing techniques and other ways to avoid spreading the infection, and offering supportive care for associated symptoms.

When this illness is properly identified and treated, prognosis is good, and most individuals recover within 4 to 5 days, with resolution of all skin problems within 2 to 3 weeks.

Diagnosing Our Patient
The patient had been treated 10 days prior for an upper respiratory tract infection, and admitted to not finishing antibiotic therapy as prescribed. She also did not change her toothbrush. She reports multiple URI's over the last 2 to 3 years that occur in the winter months. No one else in her home is presently ill.

The patient denies having a cough and displayed an itchy, raised, red papular/macular rash with a systemic diffuse pattern to the anterior and posterior trunctal area, arms, legs, and face without petechiae, which blanches when pressed. The patient reported that the rash appeared approximately 6 days after the onset of symptoms and 3 days after initiating antibiotic treatment.  She reported never having had an episode of a rash until now, and reports some relief with over-the-counter (OTC) diphenhydramine (Benadryl).

Most research about scarlet fever states that in general, it generally begins in the axilla and neck areas and can then spread systemically with petechiae. Diagnosis can be based upon the presence of a combination of manifesting symptoms and can be proven by performing either a throat culture and sensitivity test or by performing a rapid strep antigen throat swab.

The rapid strep antigen swab test has a sensitivity of 96%, a specificity of 65%, provides immediate results and is more cost effective than a throat culture and sensitivity.4 

There are other possible conditions that may result in differential diagnosis.5 These conditions, which can be ruled out based upon physical, serological, and historical findings, include: a drug hypersensitivity or an allergic reaction, Kawasaki's disease, coxsakie virus (hand, foot and mouth disease), herpes zoster, measles, mononucleosis, roseola, rubella, bacterial endocardidtis, Lyme disease, secondary syphilis, rocky mountain spotted fever, systemic lupus erythematosus, and pityriasis rosea.

The patient was advised to check with her PCP prior to ceasing antibiotic therapy in the future. Rapid strep antigen testing was not available at the clinician's office; and the patient's parent reported that she could not afford a throat culture and sensitivity, Thus, the patient was treated based upon a Centor Score of 3, her history and culmination of symptoms.

She was prescribed prednisone (a 4mg dose pack), certirizine (Zyrtec) 10mg daily, and azithromycin (Zithromax), with 500mg taken on day one and 250mg taken on days 2 through 5.

The patient was also instructed to use warm salt water gargles three times a day, and to take acetaminophen (Tylenol) or ibuprofen (Motrin) as needed for fever and body aches. The patient was also advised to finish the full course of antibiotics and to refrain from sexual activity until asymptomatic. The PCP told her she could return to school 24 hours after initiating treatment and should return for an office visit if symptoms persist or worsen.

The patient experienced an alleviation of all symptoms within 10 days. She did not report experiencing any skin sloughing. Additionally, she noted that she had replaced her toothbrush, refrained from sexual activity, and was no longer sharing her utensils with others. She has had no recurrent symptoms for 4 months and remains in good health.

Implications for Providers
When misdiagnosed, scarlet fever may lead to multiple serious complications.1,6 The most common complications include: otitis media, pneumonia, septicemia, osteomyelitis, rheumatic fever and acute glomerulonephritis. Less common complications include: cervical lymphadenitis, mastoiditis, ethmoiditis, peritonsillar abscess, sinusitis, meningitis, brain abscess, intercrainial venous sinus thrombus, meningitis, septic arthritis, acute renal failure due to poststreptoccocal glomerulonephritis, hepatitis, vasculitis and uveitis.

Educating Patients Is Paramount
Because the complications of scarlet fever can be so serious, individuals should be instructed to finish the entire course of antibiotics unless otherwise advised by their PCP, follow good hand-washing and other hygiene precautions (such as not sharing eating or drinking utensils), replace their toothbrush after the resolution of symptoms, and (perhaps most importantly) to return if symptoms worsen.3

Patients should also be informed that they may have generalized skin sloughing over the next 2 to 3 weeks,1 and they need to be educated about the warning signs of GABHS infections, such as a persistent fever, increased throat or sinus pain, generalized swelling, and worsening of symptoms.1

Thomas Christopher is a student in the family nurse practitioner program at the University of North Florida in Jacksonville, Florida.   


1. Zabawski, E. Scarlet Fever 2013. Accessed March 3, 2014.

2. U.S. Department of Health and Human Services, Scarlet Fever 2014. Accessed March 2, 2014.

3. U.S. Centers for Disease Control. Scarlet Fever: A Group A Streptococcal Infection 2014. Accessed March 3, 2014.

4. Weinstock, M., Neides, D., & Chan, M. Pharyngitis. In: The Resident's Guide to Ambulatory Care: frequently encountered and commonly confused clinical condition. 6th ed. Columbus, OH: Anadem Publishing. 2009: 31-34.

5. Monthly Prescribing Reference (MPR).  Azithromycin (Zithromax), prednisone, cetirizine (Zyrtec). 2014. Accessed March 3, 2014.

6. Sailer, C., & Wasner, S. Differential Diagnosis. 3rd ed. Hermosa Beach, Ca: Borm Bruckmeier Publishing. 2011:144-145, 336-337.

7. Choby, B.  Diagnosis and treatment of streptococcal pharyngitis. American Family Physician. 2011;79(5):383-390. Accessed March 2, 2014.

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