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Eosinophilic meningitis and an ocular worm in a patient from Kerala, south India

N N Baheti¹, M Sreedharan¹, T Krishnamoorthy², M D Nair¹, K Radhakrishnan¹

¹ Department of Neurology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
² Departments of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India

Correspondence to:
krk{at}sctimst.ac.in

Angiostrongylus cantonesis is the most common cause of eosinophilic meningitis worldwide.¹ Rats serve as the definitive host of Angiostrongylus cantonesis, whereas humans become infected by ingesting third-stage larvae in raw intermediate hosts, such as snails, prawns, fish, frogs or monitor lizards.² Infection has also rarely been acquired by the consumption of vegetables contaminated with infective larvae.^{3 4} Outside Southeast Asia and the Pacific Basin, where the infection is endemic, Angiostrongylus eosinophilic meningitis is seldom encountered.²

A 40-year-old woman, a resident of Kerala, southern India, presented with a 3-week history of low-grade fever, headache and vomiting. Other than neck rigidity, neurological and systemic examinations were normal. The blood counts showed 8.3 x 10⁹/l leucocytes with 19% eosinophils. The cerebrospinal fluid (CSF) was clear, but showed 1030 leucocytes/µl (90% lymphocytes and 10% eosinophils), protein 0.82 g/l and sugar 2.28 mmol/l. No microorganisms were identified in the CSF. Brain MRI revealed fresh and resolving lesions in the cerebellum and left thalamus (fig 1A) and a focal linear haemorrhagic lesion over the surface of the left frontal lobe, resembling a track (fig 1B). During the fourth week of illness, she complained of linear floaters in the left eye. Ophthalmological examination revealed a floating worm in the posterior vitreous (fig 1C). By parsplana vitrectomy and aspiration under local anaesthesia, a 13 mm x 0.04 mm worm was removed. Microscopic examination of the worm revealed a single stomal opening, anteriorly leading to a gastrointestinal tract, and horizontal and vertical striations on the body suggestive of an Angiostrongylus worm (fig 1D). The patient had never consumed raw snails, lizards or frogs, and cooked prawns and fish thoroughly before eating. She moved to an old house about 3 months prior to the onset of illness, in which she had noticed snails moving around in the bathroom and kitchen. Vegetables or water contaminated by snails seems to be the most probable source of Angiostrongylus cantonesis infection in our patient. The patient’s symptoms completely resolved following a 2-week course of oral albendazole 400 mg twice daily along with prednisolone 40 mg daily.

View this figure (165K): in this window | in a new window | PowerPoint for Teaching   Figure 1 (A) MRI axial FLAIR sequence shows hyperintense lesion with central hypointensity in the right cerebellum and a resolving lesion (black arrow) in the left cerebellum, which had an initial MRI appearance similar to the right cerebellar lesion. (B) MRI axial T2* gradient echo sequence shows a haemorrhagic tract over the left frontal cortex (white arrow). (C) Left optic fundus photograph shows a worm floating in the vitreous. (D) Light microscopic appearance (x40) of the anterior end of the worm; it has a single stomal opening to the gastrointestinal tract, without fleshy lips and sharp hooks.

 

The typical clinical manifestations of angiostrongyliasis are symptoms and signs of meningitis or radiculomyeloencephalitis, and an eosinophilic pleocytosis.² The MRI findings are non-specific, ranging from normal to leptomeningeal enhancement, ventricular enlargement, hyperintense signal lesions on T2-weighted images, and enhancing ring or disc lesions.⁵ Presence of haemorrhagic tracts, as seen in our patient, possibly produced by migrating worms, may be of diagnostic value.⁵

A presumptive diagnosis of angiostrongyliasis can be made in a patient presenting with eosinophilic meningitis with a history of antecedent exposure to an intermediate host. The larvae can be demonstrated in the CSF or eye in only 10% of cases.² Serological testing for diagnosis is available only in a few selected laboratories in endemic areas. Our case illustrates the difficulty in diagnosing the aetiological agent in eosinophilic meningitis in the absence of an overt history of exposure to intermediate hosts in a non-endemic area for angiostrongyliasis.

This article has been adapted from Baheti N N, Sreedharan M, Krishnamoorthy T, Nair M D, Radhakrishnan K. Eosinophilic meningitis and an ocular worm in a patient from Kerala, south India Journal of Neurology, Neurosurgery and Psychiatry 2008;79:271

Competing interests: None declared.

Individual author’s contribution and responsibilities: All the authors were involved in the care of the patient, and analysis and interpretation of data, including writing and critical revision of the report. The Corresponding Author, Dr Radhakrishnan, had full access to all the data, had final responsibility for the decision to submit for publication, and obtaining consent from the patient to do so.

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