What's the best course of action for a patient with cough, fever, dyspnea, and expulsion of a worm by mouth, who has been prescribed Mebendazole, and now presents with a murmur, cardiomegaly, pulmonary congestion, and hyperaeration on chest X-ray?

Management of Parasitic Infection with Concurrent Cardiac Decompensation

Stop mebendazole immediately and prioritize treatment of acute heart failure before addressing the parasitic infection, as the cardiac findings (murmur, cardiomegaly, pulmonary congestion) represent a life-threatening condition that takes precedence over helminth treatment. 1

Immediate Cardiac Assessment and Stabilization

The chest X-ray findings of cardiomegaly with pulmonary congestion indicate acute heart failure requiring urgent intervention 1. The newly detected murmur may represent valvular pathology or be secondary to cardiac dilation 1.

Priority diagnostic steps:

• Obtain urgent echocardiography to assess left ventricular function, ejection fraction, and valvular abnormalities, as this is the most useful method for evaluating systolic and diastolic dysfunction 1
• Measure BNP or NT-proBNP levels immediately: NT-proBNP >2000 pg/mL makes chronic heart failure likely, while <400 pg/mL makes it unlikely 1
• Perform ECG to assess for arrhythmias, ischemia, or conduction abnormalities; a completely normal ECG makes heart failure with systolic dysfunction unlikely (<10% probability) 1

Immediate treatment priorities:

• Initiate oxygen therapy with continuous oxygen saturation monitoring for all hospitalized patients 2
• Assess volume status and consider intravenous diuretics for pulmonary congestion 2
• Monitor vital signs including temperature, respiratory rate, pulse, blood pressure, mental status, and oxygen saturation at least twice daily 2, 3

Addressing the Respiratory Infection Component

The patient presents with cough, fever, and dyspnea alongside pulmonary congestion, creating diagnostic complexity 1. The hyperaeration finding suggests possible obstructive airway component or emphysema 1.

Pneumonia management in the context of heart failure:

• Initiate empiric antibiotic therapy with combination beta-lactam plus macrolide (e.g., ceftriaxone plus azithromycin) given the patient's comorbidities and hospitalization requirement 3
• Distinguish pulmonary congestion from pneumonia: pulmonary venous congestion and interstitial edema on chest X-ray confirm left heart failure, but pulmonary infection may coexist and requires treatment of both conditions 1
• Reassess clinical response at 48-72 hours; do not change antibiotics before 72 hours unless marked clinical deterioration occurs 3

Parasitic Infection Management Strategy

The expulsion of a worm by mouth indicates active helminth infection, most likely Ascaris lumbricoides given the route of expulsion 1, 4.

Critical consideration regarding mebendazole:

• Defer mebendazole treatment temporarily until cardiac status stabilizes, as the parasitic infection is not immediately life-threatening 5
• Mebendazole is poorly absorbed systemically (only 2% excreted in urine) and works primarily in the GI tract, making it relatively safe but not urgent 5
• No contraindication exists for mebendazole use with cardiac disease per FDA labeling, but stabilizing the acute cardiac decompensation takes priority 5

When cardiac status permits (typically 48-72 hours after stabilization):

• Administer mebendazole 100 mg orally twice daily for 3 consecutive days for presumed Ascaris infection 5, 6
• Consider empiric treatment with albendazole 400 mg plus ivermectin 200 μg/kg as single doses if Loeffler's syndrome (larval lung migration) is suspected, given the respiratory symptoms and eosinophilia if present 1, 4
• Obtain stool microscopy for ova and parasites on 3 separate days to identify the specific helminth and assess for mixed infections 4

Differential Diagnosis: Loeffler's Syndrome

Consider Loeffler's syndrome as a potential contributor to respiratory symptoms, which results from larval migration through lungs 1-2 weeks after acute helminth infection 1.

Clinical features supporting this diagnosis:

• Fever, cough, dyspnea, and wheeze occurring with helminth infection 1
• Migratory pulmonary infiltrates may be visible on chest radiograph 1
• Peripheral eosinophilia if present (check complete blood count) 1

Treatment approach if Loeffler's syndrome confirmed:

• Empiric treatment with ivermectin 200 μg/kg plus albendazole 400 mg as single doses during the prepatent period 1
• Consider retreatment 1 month after resolution of pulmonary symptoms to ensure adult worms are treated 4
• Use caution with corticosteroids (which may help reduce symptom duration in Loeffler's syndrome) as they can cause hyperinfection if Strongyloides is present 1

Monitoring and Follow-up

During hospitalization:

• Monitor for hepatotoxicity and leukopenia if prolonged anthelmintic treatment (>14 days) becomes necessary 4
• Assess for anemia, as chronic hookworm can cause iron-deficiency anemia 4
• Laboratory monitoring should include complete blood count, electrolytes, renal function, and liver function tests 1

Post-discharge:

• Arrange 6-week follow-up with repeat chest radiograph to ensure resolution of pulmonary findings and exclude underlying malignancy, especially given smoking history if present 2, 3
• Repeat stool examination 2-3 weeks after anthelmintic treatment to confirm parasitic clearance 4
• Echocardiographic follow-up to reassess cardiac function after acute decompensation resolves 1

Common Pitfalls to Avoid

• Do not prioritize parasitic treatment over cardiac stabilization: the cardiac findings represent immediate mortality risk while the helminth infection does not 1
• Do not assume all respiratory symptoms are from pneumonia: pulmonary congestion from heart failure can mimic or coexist with infection 1
• Do not use corticosteroids empirically for respiratory symptoms without ruling out Strongyloides, as this can cause fatal hyperinfection syndrome 1
• Do not expect rapid radiographic improvement: chest X-ray findings typically lag behind clinical improvement in both pneumonia and heart failure 2
• Do not discharge without addressing both conditions: ensure cardiac stability and complete appropriate anthelmintic therapy before discharge 1, 4