Cornelia Silaghi1, Ana Sofia Santos2, Jacinto Gomes3, Iva Christova4, Ioana Adriana Matei5, Gernot Walder6, Ana Domingos7, Lesley Bell-Sakyi8, Hein Sprong9, Friederike D von Loewenich10, José A Oteo11, José de la Fuente1213, J Stephen Dumler1415
Vector Borne Zoonotic Dis . 2017 Jan;17(1):12-22. doi: 10.1089/vbz.2016.1960.
The genus Anaplasma (Rickettsiales: Anaplasmataceae) comprises obligate intracellular Gram-negative bacteria that are mainly transmitted by ticks, and currently includes six species: Anaplasma bovis, Anaplasma centrale, Anaplasma marginale, Anaplasma phagocytophilum, Anaplasma platys, and Anaplasma ovis. These have long been known as etiological agents of veterinary diseases that affect domestic and wild animals worldwide. A zoonotic role has been recognized for A. phagocytophilum, but other species can also be pathogenic for humans. Anaplasma infections are usually challenging to diagnose, clinically presenting with nonspecific symptoms that vary greatly depending on the agent involved, the affected host, and other factors such as immune status and coinfections. The substantial economic impact associated with livestock infection and the growing number of human cases along with the risk of transfusion-transmitted infections, determines the need for accurate laboratory tests. Because hosts are usually seronegative in the initial phase of infection and serological cross-reactions with several Anaplasma species are observed after seroconversion, direct tests are the best approach for both case definition and epidemiological studies. Blood samples are routinely used for Anaplasma spp. screening, but in persistently infected animals with intermittent or low-level bacteremia, other tissues might be useful. These guidelines have been developed as a direct outcome of the COST action TD1303 EURNEGVEC (“European Network of Neglected Vectors and Vector-Borne Diseases”). They review the direct laboratory tests (microscopy, nucleic acid-based detection and in vitro isolation) currently used for Anaplasma detection in ticks and vertebrates and their application.
Keywords: Anaplasma spp.; PCR; direct diagnosis; in vitro isolation; microscopy; ticks; vertebrate hosts.