Conspecific hyperparasitism in the <i>Hyalomma excavatum</i> tick and considerations on the biological and epidemiological implications of this phenomenon

Abstract

Objective. This study presents for the first time a case of Hyalomma excavatum hyperparasitism and an analysis of this phenomenon in terms of its potential role in the biology of ticks and epidemiology of tick-borne diseases. Materials and method. Two partially engorged H. excavatum females, one fully engorged female, and 5 males were collected from a naïve rabbit and placed together in a rearing chamber at a temperature of 25 °C and 75% humidity. Results. 3-4 days after tick detachment from the host's skin, one partially engorged H. excavatum female was observed attached to the idiosoma of the fully engorged conspecific female. Conclusions. This study and observations of other authors confirm that partially engorged ixodid ticks can re-infest the host, and even co-feeding fully engorged ticks in order to collect the blood meal that is indispensable for important physiological processes. However, inefficient feeding of a partially engorged female on another conspecific female may reduce its reproductive performance and disturb the development of eggs and larvae. It seems that parasitism of a tick on another conspecific specimen, when at least one of them is infected by a microorganism, may be a yet poorly explored route of transmission of pathogens or symbionts between the ticks. Initiation of feeding by a hungry or partially engorged tick on a fully engorged specimen is an attempt to obtain food in the drastic conditions of the absence of a target host. Tick hyperparasitism with concurrent pathogen transmission can contribute to the genospecific diversity of pathogens in vectors and hosts.

The Potential Role of Migratory Birds in the Rapid Spread of Ticks and Tick-Borne Pathogens in the Changing Climatic and Environmental Conditions in Europe

“…Infected ticks may transmit pathogens in the host's blood vessel that may be picked up by other ticks feeding in the vicinity on the same host's body at the same time [15]. The transfer of certain pathogenic and non-pathogenic microorganisms can also take place via conspecific and interspecific tick parasitism [16] or, probably, during oral-anal contact between two different tick species-I. ricinus and D. reticulatus [17].…”

Tick Salivary Compounds for Targeted Immunomodulatory Therapy

“…Given their parasitic lifestyle, ticks must overcome innate immunity during their primary infestation and both innate and adaptive immunity during secondary or subsequent infestations (22). Following tick feeding, tick-derived antigens may be presented to naïve B and T cells by activated DCs that have acquired foreign antigens and have migrated to skin-draining lymph nodes (40). Both the humoral and cellular branches of host adaptive immunity are activated, thereby resulting in the generation of antigen-specific antibodies and T lymphocytes (40).…”

“…Following tick feeding, tick-derived antigens may be presented to naïve B and T cells by activated DCs that have acquired foreign antigens and have migrated to skin-draining lymph nodes (40). Both the humoral and cellular branches of host adaptive immunity are activated, thereby resulting in the generation of antigen-specific antibodies and T lymphocytes (40). In subsequent infestations, activated memory T and B lymphocytes secrete cytokines and produce specific antibodies that target tick salivary or mouthpart-derived antigens in an effort to reject the tick (41).…”

Prevalence of Ticks and detection of Rickettsial Agents from blood of Tick-Infested animals in Lower Sindh: A MOLECULAR APPROACH

“…Pasteurella multocida, brucella abortus and salmonella typhimurium in both humans as well as animals (1). Ticks have enormous capability to adapt to changing geoclimatic conditions and can therefore expand their distribution range (2). They are known as main vectors for transmission of many pathogens such as viral, bacterial, rickettsial and parasitic infestations (3).…”