While I agree high eosinophils are a sign of parasites, low or no eosinophils can not rule out their presence. Please read this article about refugees emigrating to the west. It's basically saying the longer you have been infected the less likely you will register high eosinophils. Also, they are only present during certain life cycles. It's not the best test to diagnose parasites unless you register high eosinophils. It's like the stool test. Just because it's negative that doesn't mean you don't have parasites.