What is the most likely diagnosis and recommended treatment for whitish oral plaques that develop after a recent measles infection?

Whitish Mouth Plaques Post-Measles: Diagnosis and Management

The most likely diagnosis is oral candidiasis (thrush), which commonly develops after measles due to measles-induced immunosuppression, and should be treated with topical or systemic antifungal therapy depending on severity.

Clinical Context and Pathophysiology

Measles causes profound but temporary immunosuppression that persists for weeks to months after the acute infection, creating vulnerability to opportunistic infections including oral candidiasis 1, 2, 3. The characteristic whitish oral plaques developing after measles represent pseudomembranous candidiasis, the most common form of oral fungal infection 4, 5.

• Candida albicans is present as a commensal organism in 40-65% of healthy mouths, but becomes pathogenic when host defenses are compromised 5.
• Measles-induced immunosuppression creates systemic compromise that predisposes to candidal overgrowth 1, 2.
• The pseudomembranous form presents as creamy white, plaque-like lesions on the buccal or oropharyngeal mucosa or tongue surface that can be readily scraped 4.

Diagnostic Approach

A clinical diagnosis of oral candidiasis can usually be made on visual inspection, with microbiological confirmation reserved for treatment failures or recurrent cases.

• The diagnosis is typically made on clinical grounds based on the characteristic appearance of white plaques that can be scraped off 4.
• For diagnostic confirmation, obtain samples by scraping with a tongue depressor and culture on fungal-selective media 4.
• Microscopic demonstration of fungal hyphae on PAS smear or biopsy is highly diagnostic 5.
• In the post-measles setting with typical white plaques, empiric antifungal treatment without culture is reasonable, with successful resolution confirming the diagnosis 5.

Treatment Recommendations

For mild to moderate oral candidiasis post-measles, initiate topical antifungal therapy; reserve systemic therapy for severe cases, treatment failures, or immunocompromised patients.

First-Line Topical Therapy

• Nystatin oral suspension or pastilles are safe and effective for uncomplicated oral candidiasis 5.
• Clotrimazole troches are highly effective topical agents, though they can cause liver enzyme elevations 5.
• Treatment duration should be 7-14 days, with 14 days associated with lower relapse rates 6.

Systemic Therapy Indications

• Fluconazole is the preferred systemic agent for moderate to severe oral candidiasis or when topical therapy fails 4, 6.
• Itraconazole oral solution (200 mg/day) is an alternative with similar efficacy to fluconazole, achieving approximately 84% clinical response rates 6.
• Systemic therapy is particularly important in the post-measles setting given the degree of immunosuppression 4, 1.

Treatment Duration and Monitoring

• Continue treatment for at least 7-14 days, with longer courses (14 days) associated with lower relapse rates 6.
• Monitor for treatment response within 3-5 days; lack of improvement suggests resistant organisms or incorrect diagnosis 4.
• For treatment failures, obtain cultures with species identification and susceptibility testing 4.

Important Clinical Caveats

Differential Diagnosis Considerations

While oral candidiasis is most likely post-measles, consider these alternatives:

• Koplik spots appear during the measles prodrome (before rash) as small white spots on a red background inside the mouth and are pathognomonic for measles itself 1, 7, 8.
• Koplik spots appear 2-3 days before the rash and fade as the rash develops, whereas candidiasis develops after measles resolution 1, 7.
• If white plaques appeared during the acute measles illness (with fever, cough, coryza, conjunctivitis), they likely represent Koplik spots rather than candidiasis 1, 7.

Risk Factors for Treatment Failure

• Previous fluconazole exposure increases risk of azole-resistant Candida species 4.
• Non-albicans species (C. krusei, C. glabrata) have intrinsic reduced azole susceptibility 4.
• Severe immunosuppression from measles increases risk of refractory disease 4, 1.

Prevention of Recurrence

• Address the underlying immunosuppression by ensuring adequate nutrition and vitamin A supplementation, which is recommended for all measles cases 1.
• Avoid unnecessary antibiotic use, which can predispose to candidal overgrowth 4.
• Primary antifungal prophylaxis is not recommended in immunocompetent patients recovering from measles 4.

When to Escalate Care

• Dysphagia or odynophagia suggests esophageal extension requiring endoscopic evaluation 4.
• Failure to respond to appropriate antifungal therapy within 5-7 days warrants culture, susceptibility testing, and consideration of alternative diagnoses 4.
• Recurrent episodes require investigation for underlying immunodeficiency beyond measles-induced immunosuppression 4.