Each level has a defined role supported by standard operating procedures (SOPs) that specify the safe collection, handling, storing, shipping and processing of laboratory specimens. Supervision and feedback are carried out using a level-specific checklist. The SOPs specify communication channels and procedures linking each level for the referral of laboratory specimens, reporting of data, supervision and quality assurance activities. For example, the district hospital laboratories submit weekly reports of selected priority diseases. The district level performs commonly requested laboratory tests such as hematology, clinical chemistry, urine analysis and parasitology. At the health center level, laboratories perform microscopy for detecting malaria, tuberculosis and other bacterial and parasitic agents. Almost all health center laboratories have the capacity to do human immunodeficiency virus (HIV) rapid testing. For some disease programs such as malaria, the network extends to the community level where volunteers are trained in detection and treatment of malaria including home-based management of malaria. The community volunteers contribute to surveillance activities by referring patients to health centers for laboratory services.