A review on the eco-epidemiology and clinical management of human granulocytic anaplasmosis and its agent in Europe

Abstract

Anaplasma phagocytophilum is the agent of tick-borne fever, equine, canine and human granulocytic anaplasmosis. The common route of A. phagocytophilum transmission is through a tick bite, the main vector in Europe being Ixodes ricinus. Despite the apparently ubiquitous presence of the pathogen A. phagocytophilum in ticks and various wild and domestic animals from Europe, up to date published clinical cases of human granulocytic anaplasmosis (HGA) remain rare compared to the worldwide status. It is unclear if this reflects the epidemiological dynamics of the human infection in Europe or if the disease is underdiagnosed or underreported. Epidemiologic studies in Europe have suggested an increased occupational risk of infection for forestry workers, hunters, veterinarians, and farmers with a tick-bite history and living in endemic areas. Although the overall genetic diversity of A. phagocytophilum in Europe is higher than in the USA, the strains responsible for the human infections are related on both continents. However, the study of the genetic variability and assessment of the difference of pathogenicity and infectivity between strains to various hosts has been insufficiently explored to date. Most of the European HGA cases presented as a mild infection, common clinical signs being pyrexia, headache, myalgia and arthralgia. The diagnosis of HGA in the USA was recommended to be based on clinical signs and the patient’s history and later confirmed using specialized laboratory tests. However, in Europe since the majority of cases are presenting as mild infection, laboratory tests may be performed before the treatment in order to avoid antibiotic overuse. The drug of choice for HGA is doxycycline and because of potential for serious complication the treatment should be instituted on clinical suspicion alone.

Molecular detection of Anaplasma phagocytophilum in roe deer (Capreolus capreolus) in eastern Poland

“…Other Anaplasma species such as A. platys, A. centrale, A. marginale has not been detected in roe deer. All AP isolates obtained in this study were qualified to a single ecotype, differing from the AP ecotypes found in humans, farm animals and domestic animals, as well as from those isolated from rodents, which may indicate that the roe deer in eastern Poland do not constitute a reservoir host for the human pathogenic strains of AP [36].…”

Tripartite Interactions among Ixodiphagus hookeri, Ixodes ricinus and Deer: Differential Interference with Transmission Cycles of Tick-Borne Pathogens

“…These increases are partially explained by geographical spread of its vector, Ixodes ricinus [4,5]. Other tick-borne diseases (TBDs), such as anaplasmosis and neoehrlichiosis, are also emerging [6,7]. Understanding which factors drive the population densities of ticks and the transmission cycles of tick-borne pathogens are important steps in assessing disease risk and formulating possible intervention strategies.…”

Tick-borne infections of dogs in Serbia: A review of research

“…One of the answers could be the high genetic diversity of the European A. phagocytophilum strains, which could be a consequence of adaptation of A. phagocytophilum to different host species. Circulation of four A. phagocytophilum ecotypes has been established, and it is known that ecotype/ cluster (I) is isolated significantly more often from dogs than the other ecotypes (Matei et al, 2019;Jahfari et al, 2014).…”