Best Practice No 174. Best practice guidelines for the examination of specimens for the diagnosis of parasitic infections in routine diagnostic laboratories.

Although most routine microbiology diagnostic laboratories process specimens for the diagnosis of parasitic infections, there are no best practice guidelines either for processing or for referral to specialist centres. Microscopy for parasites is most often requested on faecal samples, but urine, sputum, liver aspirates, duodenal aspirates, bile, corneal scrapings, contact lens fluid, and tissue are also encountered. Diagnosis of certain parasitic infections requires serology or polymerase chain reaction. These are undertaken in specialist laboratories, which should be consulted for expert advice on diagnosis and management of parasitic infections. Clinical Pathology Accreditation UK (CPA) has defined standards for assessing the quality of service provided by laboratories, but these do not include scientific and technical aspects. The Association of Medical Microbiologists has recently published Standards for laboratory practice in medical microbiology, which covers scientific and technical aspects, mainly bacteriological examination of specimens in routine diagnostic microbiology laboratories. These guidelines are complementary to the CPA standards and aim to ensure a consistent and high quality of service. This article provides best practice guidelines for the diagnosis of parasitic infections.