Medical Mystery of the Week

      You have recieved your COVID19 immunizations but continue to practice some Telemedicine. You are shown a picture of a boy (Panel A) and his chest x-ray and EKG (Panel B). All you are told is that he is from Puerto Rico.
       What is your diagnosis, what test(s) do you advise to substantiate your suspicions, and what treatment, if any, do you advise?
DIAGNOSIS: Chronic schistosomiasis due to infestation with Schistosoma mansoni. The patient has hepatosplenomegaly and ascites and pulmonary hypertension with right atrial and right ventricular enlargement  (Panel D, below). 

Panel A. 

The ink markings outline the liver and spleen. The rounded configuration of the abdomen and protuberance of the umbilicus are due to ascites. The patient has a granulomatous hepatitis/cirrhosis with portal hypertension and ascites due to S. mansoni infestation (see panel D, below).
      Common symptoms of acute S. mansoni infection include fever, chills, weakness, weight loss, headache, anorexia, nausea and vomiting, diarrhea, and cough lasting a few weeks to 2-3 months followed by abatement; many patients are asymptomatic. Central and/or peripheral CNS involvement can occur leading to seizures, decreased mentation, and paraparesis.
      Ten to 75% of patients  have eosinophilia (often marked). The diagnosis is best established by crushing a snip biopsy of the rectal valve between two glass slides and/or (less reliably) stool examination. ELISA tests for S. mansoni antibodies and antigens are available but have variable sensitivities and specificities. A table outlining the treatment of acute S. mansoni infection is shown in Panel E, below.                                                                                  

Panel B. 

The patient's EKG shows signs of right atrial enlargement (P wave ≥ 2.5 mm tall in one or more inferior leads (II, III, AVF), >1.5 mm V1 with normal duration) and right ventricular hypertrophy (RV1 > 6mm, R:S ration V1 >1.0, RV1+SV6 ≥ 10.5 mm). His chest x-ray shows signs of chronic pulmonary hypertension (markedly enlarged main pulmonary artery segment, prominant right atrium and right pulmonary artery, and a rounded left heart border suggestive of RVH). This was due to pulmonary embolization of S. mansoni  eggs.

Panel C.

Acute S. mansoni infection. Left image: Cercadial dermatitis ("Swimmer's itch"). This dermatitis appears ˜15 days after swimming or wading in snail-infested fresh water lakes or ponds. Right image: Pulmonary involvement in acute S. mansoni infection. The arrow points to clusters of periovular granulomas giving a "cotton candy"- like appearance .

Panel D

A CT scan of the brain of a young Brazilian woman who presented with seizures and a headache two months after bathing in a fresh water lake.The study shows a conglomerate of nodules enhanced by contrast (arrow, left image). Her brain biopsy showed well-formed granulomas surrounding S. mansoni eggs (representative granuloma, right image).

Panel E. 

A. Micrograph of a S. mansoni cercaria penetrating the skin. B. The two suckers on this adult male allows it to adhere to endothelial surfaces of portal and mesenteric veins where it grasps the female (inset) and breeds; their eggs reach the intestines where they are excreted into feces. Excreted eggs hatch in fresh water releasing miracidiae. The miracidiae invade Biomphalaria snails and reproduce asexually forming cercariae. The cercariae penetrate the skin, change into schistosomulae, enter a nearby vein, and are transported to the pulmonary capillaries via the right heart. To develop further, the worms must reach the liver via the splanchnic vasculature.  C. The serosal surfaces of the liver, spleen and mesentaries are studded with periovular granulomas. D. A micrograph of a hepatic periovular granuloma with central necrosis.
      Animal studies indicate that there is a moderate Th1 response to parasite antigens during the acute stage of schistosomiasis followed by a sustained Th2 , Th17, Tfn, and Th9 cell responses to egg-derived antigens that mediate granuloma formation and liver fibrosis. T regs are involved in down-regulating these immune reponses.

Panel F.

Recommended treatment of acute S. mansoni infection. This will cure 40-50% of patients. Regimen to be repeated if stool remains positive 2-3 months post-Rx. 
The ivermectin is to prevent dissemination of strongyloides which often coinfects persons with schistosomiasis.

S. mansoni eggs with characteristic spikes.

Reference: Lambertucci, J.R. Acute schistosomiasis mansoni: revisited and reconsidered. Mem Inst Oswaldo Cruz, Rio de Janeiro, 2010, 105, 422-435.

Last week's Bonus Question Answer

 Label the white billiard balls with the correct pocket number.

Answer: ASD - #5; LAE - #3; AI - #2; RAE - #6; TI - #1; MS - #4