The diagnosis of toxoplasmosis is usually made by serologic testing. A test that measures immunoglobulin G (IgG) is employed to work out if an individual has been infected. If it's necessary to undertake to estimate the time of infection, which is of particular importance for pregnant women, a test which measures immunoglobulin M (IgM) is additionally used alongside other tests like an avidity test. Diagnosis also can be made by direct observation of the parasite in stained tissue sections, spinal fluid (CSF), or other biopsy material. These techniques are used less frequently due to the problem of obtaining these specimens. Parasites also can be isolated from blood or other body fluids (for example, CSF) but this process are often difficult and requires considerable time.