Serological tests may also be used in forensic serology to investigate crime scene evidence. HLA-DQ8 haplotypes, negative serology, and normal histology or duodenal lymphocytosis had celiac disease. CSF pleocytosis, raised CSF protein level and positive CSF serology suggest neurosyphilis. Serology (identification of antibodies to viruses) may be useful in viral meningitis. Hemagglutination inhibition (HI) is one method of serology that detects antibodies for diagnostic purposes. Serology for toxoplasmosis is also indicated. There are several methods used for diagnosing "Bartonella" infection including microscopy, serology, and PCR. The Toxopert system helps in interpretation of time sequences of toxoplasmosis serology test results. A normal biopsy and normal serology after challenge indicates the diagnosis may have been incorrect. Diagnosis is by virus isolation, serology, and other tests. Hirszfeld also investigated tumors and the serology of tuberculosis. IFA sensitivity may range from 14-100%, causing discrepancies between PCR and serology test results. In selected patients, HIV serology and certain autoantibody testing may be done. B henselae infection can be detected by serology. Where doubt exists, the diagnosis may be confirmed by a laboratory test such as serology.