What are the differential diagnoses for suspected ascariasis?

Differential Diagnosis for Ascariasis

When evaluating a patient with suspected ascariasis, the differential diagnosis must be tailored to the specific clinical presentation—whether gastrointestinal obstruction, hepatobiliary disease, pulmonary symptoms, or peritonitis—as ascariasis mimics numerous common and uncommon conditions.

Gastrointestinal Presentations

Intestinal Obstruction in Children

• Intussusception: The most critical differential in pediatric patients presenting with colicky abdominal pain, vomiting, and obstruction, as both conditions share similar clinical features 1, 2.
• Volvulus: Must be considered when obstruction is accompanied by signs of bowel ischemia or gangrene 1.
• Other helminthic infections: Particularly heavy infections with Taenia species (beef or pork tapeworm), which can cause intestinal obstruction and passage of segments per rectum 3.
• Appendicitis: Ascariasis can trigger appendiceal inflammation, making this a key differential in children with right lower quadrant pain 1.

Dyspeptic Symptoms and Abdominal Pain

• Peptic ulcer disease: In endemic areas, ascariasis should be considered before ordering barium studies in patients with dyspeptic symptoms without complications like hematemesis or gastric outlet obstruction 4.
• Functional dyspepsia: Vague upper abdominal symptoms may mimic ascariasis, particularly when worms are present in the biliary tree 5.
• Other soil-transmitted helminths: Trichuris trichiura (whipworm) causes dysentery and rectal prolapse; Strongyloides causes abdominal pain and bloating with potential for hyperinfection 3, 6.

Hepatobiliary Presentations

Biliary Obstruction and Cholangitis

• Choledocholithiasis: Gallstones are the most common cause of biliary obstruction in adults; ultrasound may show tube-like structures in both conditions 5.
• Cholangiocarcinoma: Chronic biliary ascariasis can mimic malignancy on imaging 7.
• Fascioliasis: Causes acute abdominal pain and biliary obstruction with eosinophilia, particularly in travelers from endemic areas 3.
• Gallbladder neoplasia: Ascaris debris in the gallbladder can appear pseudotumorous on conventional ultrasound; contrast-enhanced ultrasound shows no enhancement in ascariasis but enhancement in neoplasia 7.

Pancreatitis

• Acute pancreatitis from other causes: Gallstones, alcohol, and hypertriglyceridemia are more common; ascariasis should be suspected when imaging shows worms in the pancreatic duct or when patients are from endemic areas 5, 8.
• Pancreatic adenocarcinoma: Pancreatic ascariasis can form a pseudotumor mimicking malignancy on CT/MRI, potentially leading to unnecessary pancreaticoduodenectomy 8.

Pulmonary Presentations (Loeffler's Syndrome)

Migratory Pulmonary Infiltrates with Eosinophilia

• Acute schistosomiasis (Katayama syndrome): Presents 2–8 weeks after freshwater exposure with fever, cough, urticarial rash, and marked eosinophilia (sometimes >5 × 10⁹/L) 3.
• Strongyloidiasis: Causes wheeze, dry cough, and eosinophilia; critical to exclude before steroid use due to hyperinfection risk 3, 6.
• Toxocariasis: Presents with wheeze, cough, hepatosplenomegaly, and eosinophilia; ocular larva migrans may occur without eosinophilia 3.
• Tropical pulmonary eosinophilia: Caused by lymphatic filariasis (Wuchereria bancrofti), presents with dry cough, wheeze, and fever 3.
• Paragonimiasis: Causes pleuritic chest pain, pleural effusion, and eosinophilia in travelers from Asia 3.

Peritonitis and Perforation

Acute Abdomen with Peritonitis

• Perforated peptic ulcer: More common in adults; ascariasis-induced perforation is rare even in endemic areas but should be considered in patients from tropical/temperate regions with a history of worm passage 1.
• Perforated appendicitis: Ascariasis can cause appendiceal perforation, making this a key differential 1.
• Ischemic bowel: Volvulus secondary to heavy worm burden can lead to intestinal gangrene and perforation 1.

Genitourinary Presentations

Urinary Tract Symptoms

• Urinary tract infection: Dysuria and lower abdominal pain are common; urinary ascariasis is rare but should be considered in endemic areas when routine urine microscopy reveals motile helminths 9.
• Schistosomiasis (S. haematobium): Causes hematuria, dysuria, and proteinuria; eosinophilia may be present during Katayama syndrome 3.

Other Helminthic Infections with Overlapping Features

• Enterobiasis (Enterobius vermicularis): Causes pruritus ani and vaginal discharge, not typically confused with ascariasis unless gastrointestinal symptoms are prominent 3.
• Taeniasis: Beef or pork tapeworm causes diarrhea and passage of segments; neurocysticercosis from T. solium causes seizures and headache 3.
• Trichinellosis: Presents with periorbital edema, myocarditis, fever, and upper abdominal pain after consuming undercooked pork 3.

Key Diagnostic Pitfalls

• Prepatent period: Stool microscopy remains negative for 2–3 months after infection, during which pulmonary symptoms (Loeffler's syndrome) may be the only manifestation 6.
• Eosinophilia timing: Eosinophilia is transient during tissue migration and may be absent during established intestinal infection 6.
• Imaging mimicry: Ascaris debris in the gallbladder or pancreatic duct can mimic neoplasia or stones; contrast-enhanced ultrasound or MRCP is essential for differentiation 7, 8.
• Geographic history: Always obtain travel or migration history from endemic regions (Africa, Asia, South America) to raise suspicion for ascariasis and other helminthic infections 3, 6.