Real-Time Polymerase Chain Reaction Detection of Angiostrongylus cantonensis DNA in Cerebrospinal Fluid from Patients with Eosinophilic Meningitis

Abstract

Angiostrongylus cantonensis is the most common infectious cause of eosinophilic meningitis. Timely diagnosis of these infections is difficult, partly because reliable laboratory diagnostic methods are unavailable. The aim of this study was to evaluate the usefulness of a real-time polymerase chain reaction (PCR) assay for the detection of A. cantonensis DNA in human cerebrospinal fluid (CSF) specimens. A total of 49 CSF specimens from 33 patients with eosinophilic meningitis were included: A. cantonensis DNA was detected in 32 CSF specimens, from 22 patients. Four patients had intermittently positive and negative real-time PCR results on subsequent samples, indicating that the level of A. cantonensis DNA present in CSF may fluctuate during the course of the illness. Immunodiagnosis and/or supplemental PCR testing supported the real-time PCR findings for 30 patients. On the basis of these observations, this real-time PCR assay can be useful to detect A. cantonensis in the CSF from patients with eosinophilic meningitis.

Figure 1.

The clinical course and timing of laboratory tests of three patients whose date of infection was known. Serial lumbar punctures were performed at the discretion of the clinicians taking care of the patients to monitor the clinical course and relieve headaches. Number of days after time of infection is outlined on the x axis. S = first symptom onset. Filled symbols = collection of cerebrospinal fluid (CSF) that tested positive (plus sign) or negative (minus sign) in the real-time polymerase chain reaction (PCR) assay; open symbols = collection of serum that tested positive (plus sign) or negative (minus sign) in serology. Open boxes denote drug treatment (corticosteroids for all three plus albendazole for patient 2010-5). Striped boxes symbolize days of hospitalization; note that two of the patients were hospitalized twice, because of worsening symptoms due to too rapid corticosteroid dose reduction. The clinical outcome reported around 3 months after infection is outlined on the far right.

Figure 2.

Photomicrograph of a subadult male Angiostrongylus cantonensis worm isolated from the cerebrospinal fluid (CSF) of a 9-month-old boy (patient 2011-6). The anterior and posterior ends of the worm are present in the image, and the arrows point to the very long left spicule and the developing bursa (arrowheads) on the tail. Note that there is some host tissue encircling the worm to the right of the lower arrow. Scale bar = 50 μm. Inset is higher magnification of bursa showing greater level of detail. Scale bar = 15 μm.