RESUMEN
The presence of eosinophils in the cerebrospinal fluid (CSF) should always be considered abnormal. This study aimed to evaluate the causes of eosinophils in the CSF of patients who are HIV positive and HIV negative. This is the first study of eosinophils in the CSF of patients who are HIV-positive. This was a retrospective study of CSF reports from 1996 to 2005, patients were selected based on the presence of eosinophils in the CSF. We analyzed 20,008 CSF reports; eosinophils were present in 5%. The median and interquartile range (IQR) of eosinophils was 2% (1%, 4%). Eosinophilic meningitis (CSF eosinophils ≥ 10%) was present in 12% of the samples. The main etiologies were infectious diseases as follows: neurocysticercosis, Cryptococcus sp. meningitis, and acute bacterial meningitis. In HIV-positive cases, all causes were by infectious disease, the main pathogen being Cryptococcus sp. The probability of neurocysticercosis in a patient from an endemic region who is HIV-negative and has CSF eosinophils more than 10% was five times higher compared to a person without eosinophilic meningitis. There was a weak positive correlation between CSF eosinophils and increased serum eosinophils. Among the HIV-negative cases, the most frequent non-infectious causes were cerebrovascular syndromes, of these hemorrhage (91.5%). In the HIV-positive group, there were no cases of non-infectious cerebral disease. CSF eosinophils are suggestive of disease. The causes must be investigated, considering the most prevalent infectious diseases in the region.