Angiostrongyliasis laboratory findings: Difference between revisions
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==Laboratory Findings== | ==Laboratory Findings== | ||
The diagnosis of disease caused by ''Angiostrongylus cantonensis'' infestation is often difficult and relies heavily on the history of a likely ingestion of a commonly infested host and the presence of typical features of the disease. The presumptive diagnosis is particularly strong when eospinophilic meningoencephalitis can be confirmed. The diagnosis of Eosinophilic Meningitis can be arrived at through detection of elevated cranial pressure and increased numbers of eosinophils. The diagnosis of the cause of eosinophilic meningitis and the presence of ''A. cantonensis'' is remarkably more difficult. A spinal tap, or a sample of CSF, must be taken to search for ''A. cantonensis'' worms or larvae. ''A. cantonensis'' is undetectable in the CSF of more than half of the infected individuals. Current methods of detecting specific antigens associated with ''A. cantonensis'' are also unreliable. Consequently, alternative approaches to detect antigen-antibody reactions are being explored, such as Immuno-PCR. | |||
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. | 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. | ||
Revision as of 15:51, 10 August 2015
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Laboratory Findings
The diagnosis of disease caused by Angiostrongylus cantonensis infestation is often difficult and relies heavily on the history of a likely ingestion of a commonly infested host and the presence of typical features of the disease. The presumptive diagnosis is particularly strong when eospinophilic meningoencephalitis can be confirmed. The diagnosis of Eosinophilic Meningitis can be arrived at through detection of elevated cranial pressure and increased numbers of eosinophils. The diagnosis of the cause of eosinophilic meningitis and the presence of A. cantonensis is remarkably more difficult. A spinal tap, or a sample of CSF, must be taken to search for A. cantonensis worms or larvae. A. cantonensis is undetectable in the CSF of more than half of the infected individuals. Current methods of detecting specific antigens associated with A. cantonensis are also unreliable. Consequently, alternative approaches to detect antigen-antibody reactions are being explored, such as Immuno-PCR.
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.
Lumbar puncture
Lumbar puncture should always be done is cases of suspected meningitis. In cases of eosiniphilc meningitis it will rarely produce worms even when they are present in the CSF, because they tend to cling to the end of nerves. Larvae are present in the CSF in only 1.9-10% of cases. However, as a case of eosiniphilic meningitis progresses, intracranial pressure and eosiniphil counts should rise. Increased levels of eosinophils in the CSF is a trademark of the eosiniphilic meningitis.
Brain imaging
Brain lesions, with invasion of both gray and white matter, can be seen on a CT or MRI. However MRI findings tend to be inconclusive, and usually include nonspecific lesions and ventricular enlargement. Sometimes a hemorrhage, probably produced by migrating worms, is present and of diagnostic value.
Serology
In patients with elevated eosiniphils, serology can be used to confirm a diagnosis of Angiostrongylias rather than infection with another parasite. There are a number of immunoassays that can aid in diagnosis, however serologic testing is available in few labs in the endemic area, and is frequently too non-specific. Some cross reactivity has been reported between A. cantonensis and trichinosis, making diagnosis less specific.
The most definitive diagnosis always arises from the identification of larvae found in the CSF or eye, however due to this rarity a clinical diagnosis based on the above tests is most likely.