Ascariasis Differential Diagnoses

Updated: Oct 01, 2021
  • Author: Amber Mahmood Bokhari, MBBS; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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DDx

Diagnostic Considerations

Children from or in endemic areas are particularly prone to ascariasis infection and complications. In most cases, stool examination is positive for ova after a few weeks of infection.

Diagnosis 

Pulmonary ascariasis should be high on the differential in individuals with no prior Ascaris exposure and potential egg ingestion within weeks prior to onset of respiratory symptoms (dry cough, dyspnea, fever, wheezing), characteristic radiographic findings (migratory bilateral round infiltrates), peripheral eosinophilia, and relevant epidemiologic exposure to eggs of A. lumbricoides or A. suum. The diagnosis may be definitively established via visualization of Ascaris larvae in respiratory secretions or gastric aspirates although this is rarely possible. Symptomatic pulmonary involvement is rare among individuals in highly endemic areas with ongoing exposure.

Stool examination is not useful for diagnosis of pulmonary infection, since eggs are generally detected in the stool at least 40 days following pulmonary symptoms. A positive stool examination for Ascaris eggs at the time of respiratory symptoms does not establish a causal diagnosis of pulmonary ascariasis, since these eggs reflect infection acquired 2 to 12 months earlier.

Differential diagnosis with i ntestinal manifestations:

Other parasitic infestations:  Infection with other parasites should be considered due to frequent coinfection as the epidemiologic factors are common. Round worms, hookworms (A duodenale and N americanus), Trichuris (whipworm), Enterobius (pinworm), and Strongyloides stercolis are the most common parasites. These can be differentiated based on morphology of eggs, larvae, and worms via stool microscopy.

Malabsorption:  Any parasitic infestation like hookworm and Strongyloides can present with malabsorption. However, other causes must be considered, including liver cirrhosis, intestinal resection, enzyme deficiency, and Whipple procedure, with relevant testing.

Bowel obstruction: Intestinal adhesions secondary to trauma or inflammatory bowel disease, herniation, neoplasm, irradiation, and foreign body ingestion can present with a similar clinical scenario and can be differentiated radiographically.

Biliary obstruction : The main causes are intestinal fluke infections (Clonorchis and Fasciola), gallstones with cholangitis and/or cholecystitis, strictures, and malignancy. These can be differentiated by radiographic imaging, including endoscopic retrograde cholangiopancreatography and MRCP, and relevant laboratory testing.

Acute pancreatitis: Alcohol, infections, and mechanical obstruction from gallstones can cause biliary obstruction that can be confirmed with imaging and labs with a relevant exposure history.

Differential diagnosis with lung manifestations:

Eosinophilic pneumonitis:  Pulmonary eosinophilia is seen with various parasitic infestations like Filariasis, AscarisStrongyloides, hookworm (A. duodenaleN. americanus,Toxocara) and schistosomiasis. This is confirmed by stool microscopy and epidemiological exposure. However, diagnostic consideration must be given to non-infectious causes such as eosinophilic pneumonia, asthma, and hypersensitivity pneumonitis, which can be confirmed with relevant clinical labs and imaging.

Differential Diagnoses