Angiostrongyliasis

Overview

Angiostrongyliasis is an infection by a nematode from the Angiostrongylus genus of kidney and alimentary tract roundworms. For example, infection with Angiostrongylus cantonensis can occur after consuming raw Giant African land snails, Great Grey Slugs, or other mollusks.
In humans, Angiostrongylus is the most common cause of eosinophilic meningitis or meningoencephalitis. Frequently the infection will resolve without treatment or serious consequences, but in cases with a heavy load of parasites the infection can be so severe it can cause permanent damage to the CNS or death.

Symptoms

Infection first presents with severe abdominal pain, nausea, vomiting, and weakness, which gradually lessens and progresses to fever, and then to CNS symptoms and severe headache and stiffness of the neck. Also, Eosinophilic meningitis and Hyperesthesia are also present in the patietns.

Eye invasion:
Symptoms of eye invasion include visual impairment, pain, keratitis, and retinal edema. Worms usually appear in the anterior chamber and vitreous and can sometimes be removed surgically. The parasite is rarely seen outside of endemic areas, and in these cases patients generally have a history of travel to an endemic area.

Severe/CNS infection:
CNS symptoms begin with mild cognitive impairment and slowed reactions, and in a very severe form often progress to unconsciousness. Patients may present with neuropathic pain early in the infection. Eventually severe infection will lead to ascending weakness, quadriparesis, areflexia, respiratory failure, and muscle atrophy, and will lead to death if not treated. Occasionally patients present with cranial nerve palsies, usually in nerves 7 and 8, and rarely larvae will enter ocular structures. Even with treatment, damage to the CNS may be permanent and result in a variety of negative outcomes depending on the location of the infection, and the patient may suffer chronic pain as a result of infection.

Diagnosis

Diagnosis of Angiostrongyliasis is complicated due to the difficulty of presenting the angiostrongylus larvae themselves, and will usually be made based on the presence of eosiniphilic meningitis and history of exposure to snail hosts. Eosiniphilic meningitis is generally characterized as a meningitis with >10 eosiniphils/μL in the CSF or at least 10% eosiniphils in the total CSF leukocyte count. Occasionally worms found in the cerebrospinal fluid or surgically removed from the eye can be identified in order to diagnose Angiostrongyliasis.

Treatment

Treatment of angiostrongyliasis is not well defined, but most strategies include a combination of anti - parasitics to kill the worms, steroids to limit inflammation as the worms die, and pain medication to manage the symptoms of meningitis.