Role of Birds in Tick-Borne Diseases

Abstract

Ticks are considered as the second most potential source of vector-borne diseases to humans. Migratory birds are long-distance transporters of ticks and have been accounted for carrying different human pathogens such as tick-borne encephalitis virus, Crimean Congo Hemorrhagic Fever (CCHF) virus, Anaplasma marginale, Babesia divergens, Anaplasma phagocytophilium, Ehrichia, and Borrelia burgdorferi. The majority of the cases of human parasitism are identified with hard ticks compared to soft ticks. Ixodes persulcatus and Ixodes ricinus are the most important vectors for tick-borne pathogens in Asia and Europe, respectively. CCHF is a tick-borne zoonotic viral endemic in Asia, Africa, the Middle East, and Eastern Europe. CCHF virus was identified around 31 species of ticks in seven genera of the Ixodidae family. Amid the different genera of Ixodidae, the most proficient and basic vectors for CCHF are the members of the genus Hyalomma in which transovarial and transstadial transmission of infection can be seen. CCHF causes no disease in animals but causes a hemorrhagic disease in humans. Dermanyssus gallinae, also known as the Poultry Red Mite, is a hematophagous parasite that infects many bird species and is associated with the transmission of various poultry pathogens, including zoonotic pathogens like Salmonella enteritidis, Borrelia burgerdorferi, and Avian Influenza virus. Birds also serve as vectors for Trichobilharzia szidati, a lung fluke which usually lodges in the lungs of birds and can cause severe parasitic pneumonia, followed by lymphatic lesions and additionally death of the animal in extreme cases. The most commonly used serologic tests for TBD diagnoses are enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescent assay (IFA), and western blot. Microscopy and PCR offer good choices and use of immunodominant epitopes can improve protein-based diagnostic methods. Treatment modalities, such as doxycline, are available for bacterial and parasitic infections are no specific antiviral treatment available but not for viral infections.