Investigation of Antibody Response to Anaplasma phagocytophilum Immunodominant Targets During Early Phase Seroconversion in Cats and Dogs from Europe

Abstract

Abstract Anaplasmosis is a tick-borne infection caused by the bacterium Anaplasma phagocytophilum, transmitted by Ixodes spp. ticks. It infects humans and a wide variety of domestic and wild animals worldwide. Anaplasmosis in humans is known as Human Granulocytic Anaplasmosis (HGA). It is characterized by severe systemic flu-like illness with hematologic abnormalities and mild hepatitis. HGA can have a severe effect on persons with underlying health conditions as well as immunocompromised and older adults. Early detection and treatment when antibacterial therapy is most effective has proven to have a positive impact on humans affected by tick-borne diseases. (Rikihisa, 2011) Infected dogs and cats serve as sentinels for the presence of these pathogens in ticks in their geographical area and indicate if there is risk of people exposed to that same tick vector. Dogs and cats can also serve as a useful animal model for tick transmission. Emerging infections with Anaplasma species have become more frequently diagnosed in humans. Since animal reservoirs and tick vectors have increased in numbers, the threat to public health is increasing with newly emerging Anaplasma agents in areas where reservoir and tick population are high (CDC). However, there is little progress to improve early detection and early treatment of animals that are infected. Early signs and symptoms of these illnesses are nonspecific or mimic other illnesses, which can make diagnosis challenging. Current options for diagnosing anaplasmosis in companion animals include blood smear analysis, molecular and serologic testing. Each have their own benefit, cost, and expertise requirement to obtain accurate results, but not all are available to veterinarians. Inductive reasoning was used to determine that a second-generation of 4Dx® Plus SNAP® improves early detection of anaplasmosis relative to the prior generation of 4Dx® Plus SNAP® in cats and dogs with positive Anaplasma PCR results in European countries. The early detection with this enhanced diagnostic technology is due to the recognition of IgM and IgG by immunodominant targets as measured on ELISA and IFA of a geographically diverse population of serum samples. This improved detection gives a more representative estimate of the extent of anaplasmosis in the pet population and regional tick vectors. Based on current companion animal health care practices in Europe, testing for vector borne diseases generally occurs when the animals are exhibiting clinical signs versus wellness visits in the United States. This study will be part of an educational campaign to promote tick-borne screening and regular application of tick preventative to drive awareness of locally relevant tick-borne diseases. (Schäfer et al., 2022; Sainz et al., 2015) Awareness by veterinarians and pet owners helps to modify behaviors which limit contact with vectors or prevent transmission via vaccination.