Clinical Pearls & Morning Reports
Published September 26, 2018
Characteristic histologic findings associated with Angiostrongylus costaricensis infection include massive transmural eosinophilic infiltration and eosinophilic vasculitis with an intravascular nematode. Read the latest Case Records of the Massachusetts General Hospital here.
Q: What is the most frequently affected intestinal site in cases of abdominal tuberculosis?
A: Abdominal tuberculosis accounts for approximately 5% of all cases of tuberculosis and is one of the most common forms of extrapulmonary tuberculosis. The clinical symptoms are varied and often protean, and the ileocecal region is the most frequently affected intestinal site.
Q: Does schistosomiasis caused by Schistosoma mansoni more commonly occur in the proximal colon or the distal colon?
A: Schistosomiasis affects more than 200 million people worldwide, and different species of schistosoma are prevalent in different regions of the world. S. mansoni is found in the Caribbean and South America. S. mansoni adults mate and deposit eggs in the colonic submucosa, and chronic infection can lead to a colonic mass. This helminth preferentially migrates to the inferior mesenteric vein, and thus inflammatory changes more commonly occur in the distal colon than the ascending colon.
A: There are two members of the angiostrongylus genus that cause disease in humans. A. costaricensis was initially discovered in Costa Rica but has been reported throughout Central America, South America, and the Caribbean. Rats, marmosets, and coati are the definitive hosts. Adult parasites living in these hosts lay eggs, which are excreted in feces and then ingested by paratenic hosts, such as snails, slugs, freshwater crabs, and crayfish. Infection in humans can occur after ingestion of undercooked freshwater crabs or crayfish or ingestion of produce contaminated by snails or slugs. Incubation can be as short as 3 to 4 weeks, but in some cases, a more indolent course can develop, over a period of months. This invasive helminth migrates to the ileocecal region and releases eggs into the intestinal wall, causing inflammation, sometimes mass lesion, and often a peripheral eosinophilia.
A: In most patients who are infected with A. costaricensis, symptoms resolve spontaneously. Severe cases can lead to surgery for the diagnosis and definitive treatment of the infection. In young children, infection with A. costaricensis can mimic appendicitis, and many cases are found incidentally during surgery for presumed appendicitis. There is no proven role for anthelmintic therapy, and such treatment may initially worsen the disease.