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Diagnosis

Angiostrongylus cantonensis

A diagnosis of A. cantonensis is strongly suggested when symptoms suggest bacterial meningitis but testing reveals eosinophilia either in the blood (>5%) or in cerebrospinal fluid (>10%) and travel history reveals recent travel to endemic areas of the world. History of ingestion of raw or undercooked intermediate hosts or possibly transport hosts is a crucial clue as well. However, ill persons may not be aware of ingestion of foods that could lead to infection. Examination of the CSF can reveal eosinophilia (>10% eosinophils), elevated protein, and low or normal CSF glucose. It is important to note, however, that eosinophilia in the CSF and in the blood may not be present on initial presentation or in late stages of infection. The CSF pressure is generally elevated. Recovery of A. cantonensis from the CSF confirms the diagnosis; however, the organism is rarely detected on microscopy as it can adhere to the meninges.

Serologic tests have been developed but are not commercially available. A few specialty or research laboratories offer serologic tests, but the sensitivity and specificity of the tests may not be optimal and the infection is often identified only on convalescent sera. In addition, some research laboratories have developed PCR tests for use with CSF and tissue. Because of the difficulty in making the diagnosis, it is important to rule-out other causes of eosinophilic meningitis. Neuroimaging studies can be useful as there usually is an absence of focal lesions on CT scan, which helps to distinguish A. cantonensis eosinophilic meningitis from focal lesions which may be seen in neurocysticercosis and gnathostomiasis. Because eggs are not passed in the feces, a stool examination is not useful for diagnosis.

Angiostrongylus costaricensis

Although several serologic tests have been developed by researchers, they are not readily available. Cases are often diagnosed postoperatively by examination of surgical specimens. Most patients have leukocystosis, often with a high percentage of eosinophils (>10%). Radiologic examination of the gastrointestinal tract may demonstrate edema and spasticity in the areas of inflammation. Because eggs are not passed in the feces, a stool examination is not useful for diagnosis. The parasitic differential diagnosis includes anisakiasis and toxocariasis.

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Treatment

Angiostrongylus cantonensis

Treatment is usually supportive with the use of analgesics for pain and corticosteroids to limit the inflammatory reaction. Careful removal of CSF at frequent intervals can help to relieve headache in patients with elevated intracranial pressure. No anti-helminthic drugs have been proven to be effective in treatment, and there is concern that anti-helminthics could exacerbate neurological symptoms due to a systemic response to dying worms. The effectiveness of any regimen may vary by endemic region. One randomized, placebo-control study of a 2-week course of prednisolone (60 mg per day in 3 divided doses) found that the corticosteroids reduced the median length of headache from 13 days to 5 days and reduced the need for repeat lumbar puncture. Additionally 9.1% of treatment patients compared to 45.5% of controls still had headache at 2 weeks.

In two small cases series (41 and 26 adults, respectively) adult patients were given prednisolone 60 mg/day and an anti-helminthic (mebendazole 10 mg/kg/day or albendazole 15mg/kg/day two weeks, respectively), resulting in resolution of headache in a median of 3 days in the mebendazole case-series and 4 days in the albendazole case-series without serious side effects. As there was no control group, it is difficult to determine if the anthelminthic provided additional benefit. Comparing the results from the placebo-control trial to the 2 case-series, 9.1% of prednisolone monotherapy patients, 9.8% of prednisolone-mebendazole patients, and 11.5% of prednisolone-albendazole patients still had headache after 2 weeks. One small trial that directly compared prednisolone monotherapy to prednisolone-albendazole combined therapy found no benefit of adding albendazole to the regimen.

Additional symptomatic treatment may also be required for nausea, vomiting, and in some cases chronic pain due to nerve damage and muscle atrophy.

Angiostrongylus costaricensis

There is no proven treatment for illness caused by A. costaricensis and there is some concern that treatment with anthelminthics could result in worsening of the disease. Acute episodes may resolve spontaneously or require surgical treatment for intestinal inflammation.

Mebendazole

Mebendazole is available in the United States only through compounding pharmacies.

Note on Treatment in Pregnancy

Mebendazole is in pregnancy category C. Data on the use of mebendazole in pregnant women are limited. The available evidence suggests no difference in congenital anomalies in the children of women who were treated with mebendazole during mass treatment programs compared with those who were not. In mass treatment programs for which the World Health Organization (WHO) has determined that the benefit of treatment outweighs the risk, WHO allows use of mebendazole in the 2nd and 3rd trimesters of pregnancy. The risk of treatment in pregnant women who are known to have an infection needs to be balanced with the risk of disease progression in the absence of treatment.

Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.

Note on Treatment During Lactation

It is not known whether mebendazole is excreted in breast milk. The WHO classifies mebendazole as compatible with breastfeeding and allows the use of mebendazole in lactating women.

Note on Treatment in Pediatric Patients

The safety of mebendazole in children has not been established. There is limited data in children age 2 years and younger. Mebendazole is listed as an intestinal antihelminthic medicine on the WHO Model List of Essential Medicines for Children, intended for the use of children up to 12 years of age.

Albendazole

Oral albendazole is available for human use in the United States.

Note on Treatment in Pregnancy

Albendazole is pregnancy category C. Data on the use of albendazole in pregnant women are limited, though the available evidence suggests no difference in congenital abnormalities in the children of women who were accidentally treated with albendazole during mass prevention campaigns compared with those who were not. In mass prevention campaigns for which the World Health Organization (WHO) has determined that the benefit of treatment outweighs the risk, WHO allows use of albendazole in the 2nd and 3rd trimesters of pregnancy. However, the risk of treatment in pregnant women who are known to have an infection needs to be balanced with the risk of disease progression in the absence of treatment.

Pregnancy Category C: Either studies in animals have revealed adverse effects on the fetus (teratogenic or embryocidal, or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the fetus.

Note on Treatment During Lactation

It is not known whether albendazole is excreted in human milk. Albendazole should be used with caution in breastfeeding women.

Note on Treatment in Pediatric Patients

The safety of albendazole in children less than 6 years old is not certain. Studies of the use of albendazole in children as young as one year old suggest that its use is safe. According to WHO guidelines for mass prevention campaigns, albendazole can be used in children as young as 1 year old. Many children less than 6 years old have been treated in these campaigns with albendazole, albeit at a reduced dose.

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  • Page last reviewed: November 2, 2010
  • Page last updated: November 2, 2010
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