Ascariasis-associated worm encephalopathy in a young child

Introduction

Infestation with Ascaris lumbricoides is widely prevalent among children and adolescents living in reasonably developing countries. Affected children are usually asymptomatic, but may of them manifest with abdominal pain, abdomen distension, steatorrhea and hypovitaminosis A. Rare complications of the infestation result from involvement of the lung, hepato-biliary system and central nervous system. ¹

Case history

An 18-month-old boy, from a low socioeconomic class, had a history of episodic vomiting for two days. The vomiting was non-bilious and non-projectile. During a bout of vomiting, he threw up three long (approximately 25 cm) Ascaris worms. There was no history of any fever. Approximately eight hours before coming to paediatric emergency, he had abnormal movements of limbs, with uprolling of eye balls and altered sensorium. Abnormal movements were generalized tonic-clonic in nature and there was no incontinence of urine or stool and no tongue biting. The duration of abnormal movements was for approximately two minutes. The child was unconsciousness for approximately 10 minutes postictally. The event was witnessed by the child's mother and she was reliable as she was able to imitate the event. The child was developmentally normal and had no seizures in the past. At presentation he was lethargic, did not recognize his parents and spoke incoherent words. His airway was maintainable and he had normal breathing and circulation. The child had a Glasgow Coma Score (GCS) of 10 and the pupils were of equal size and reacting to light. Muscle tone and deep tendon reflexes were normal. Bilateral plantar reflexes were downgoing. There was no neck stiffness or any signs of meningismus. He had abdominal distension and there was a lump palpable around the umbilicus. Ultrasonography of the abdomen revealed worms in the jejunal lumen. Cerebrospinal fluid (CSF) examination showed no leucocytes and had normal sugar and protein. CSF culture was sterile. Hemogram was normal except for low haemoglobin (8.0 gm/dL). The ionized calcium, blood sugar, and serum sodium and potassium were all within normal limits. The other biochemical parameters, including liver function test and renal function tests, were also normal. For the seizure, he was loaded with phenytoin and he had no seizure recurrence thereafter. There was no improvement in sensorium even 12 hours after admission. He was given 10 mg/kg/day of pyrantel pamoate for two consecutive days. The child improved rapidly with a normal sensorium in the next 48 hours. He did not receive any other antibiotics.

Discussion

Infestation with Ascaris lumbricoides may be asymptomatic or it may have both intestinal and extra-intestinal complications. In a hospital-based study from Burma, out of a total 641 cases of ascariasis in children, the majority (57.7%) of patients were admitted to the hospital due to intestinal obstruction; the next common reasons for hospitalization were intestinal colic (33.0%) and hepatic ascariasis (3.3%). ² No case had encephalopathy due to Ascaris in their study. The important hepato-biliary complications of ascariasis include acute cholecystitis, acute cholangitis, biliary colic, acute pancreatitis, hepatic abscesses, pyogenic cholangitis, intrahepatic duct and bile duct calculi due to dead worms forming the nidus of stones. ³

Encephalopathy due to Ascaris infestation is very unusual and only a few case reports are present in literature. Bapat et al. reported a case of a four-year-old male child, who had a history of passing a worm ball in stools and one roundworm through his vomit, and was brought to emergency in deep coma. After initial improvement, he developed icterus due to a roundworm in the gallbladder giving rise to obstructive jaundice. He was given mebendazole and the biliary ascariasis was surgically treated. ¹ Another patient, a 3.5-year-old girl from Turkey, was admitted to the hospital with coma. She had a history of abdominal pain lasting for a week, and passing an ascaris worm by vomitus two days prior to this. She was treated with pyrantel pamoate and recovered. ⁴ The encephalopathy in this present case also responded dramatically to antihelminthic treatment. The CSF analysis was normal as in previously-reported cases. Neuroimaging could not be possible due to financial constraints as the family was poor. To the best of our knowledge, this is the youngest child who had encephalopathy due to Ascaris infestation.

Although the exact mechanism for central nervous system symptoms associated with ascariasis still remains unclear, it has been attributed to either the adverse effects of toxins produced by the larvae or adult worms or their metabolites, such as acetaldehyde. Another hypothesis extended is an allergic or immune mechanism involving an antigen-antibody type of reaction in hypersensitive nervous tissue. ⁵ Lakhontov et al. reported 17 cases with seizures probably due to ascariasis or other helminth infestations and demonstrated that the removal of helminths led to an arrest of convulsive seizures, but they recurred with a new infestation. ⁶

Various drugs have been used for ascariasis, including albendazole, mebendazole, pyrantel pamoate and piprazine. In a trial involving 185 school children, pyrantel pamoate at a dose of 20 mg/kg body weight for 1–3 days was found to be very effective against Ascaris and moderately effective against hookworm, with mean cure rates ranging from 93.3–96.7% and 53.3–73.3%, respectively and it was well tolerated. ⁷ In conclusion, encephalopathy is a rare manifestation of ascariasis, but it should be considered as a differential diagnosis for unexplained encephalopathy in tropical areas.