Coexistence of Tick-Borne Pathogens in Ticks Collected from their Hosts in Sardinia: an Update

Abstract

Purpose In recent decades, the incidence and distribution of tick-borne diseases have increased worldwide, attracting the attention of both clinicians and veterinarians. In Sardinia, notifiable tick-borne diseases are spreading and Mediterranean spotted fever (MSF) rickettsiosis continues to be endemic with an incidence of 10/10,000 inhabitants per year. Furthermore, ticks can transfer more than one pathogen after a single blood meal from a coinfected host or after multiple feeding on different infected hosts. The aim of this study was to update information on ticks and tick-borne diseases, focusing also on the presence of coinfection in Sardinian ticks. Methods The presence of protozoan (Theileria and Babesia species) and bacterial pathogens (Rickettsia spp., Anaplasma spp., Ehrlichia canis, Chlamydia spp., Bartonella spp., and Coxiella burnetii) was evaluated in 230 ticks collected from different hosts in Sardinia. Results PCR and sequencing analyses highlighted that the 59% of ticks were infected with at least one pathogen while the 15% resulted in coinfection by double and triple pathogens. Among the double co-infections, those of E. canis/C. burnetii, Babesia sp. Anglona/Ch. psittaci and Babesia sp. Anglona/C. burnetii revealed a statistically significant index of coinfection. Conclusion This study identifies new pathogens in Sardinian ticks and updates the information about tick-borne diseases in the island. We also provide new results on the presence of coinfections in collected ticks. The knowledge about the diversity of ticks and tick-borne diseases circulating in Sardinia is a necessary step toward implementing effective tick-borne disease prevention and control programs.

Rickettsiales in Italy

“…Haemaphysalis punctata Mouflon [32] Ixodes festai Hedgehog [32] Rhipicephalus bursa Mouflon, cattle, fox [32] Rhipicephalus sanguineus s.l. Cat, fox, goat, marten, mouflon [32] Candidatus Ehrlichia walkerii Ixodes ricinus Dog, goat, human, sheep, vegetation, [12,16,23,33] E. ovina Haemaphysalis punctata Sheep [10] E. canis Cediopsylla inaequalis Fox [9] Dermacentor marginatus Mouflon, wild boar [27,34] Pathogens 2021, 10,…”

“…Haemaphysalis punctata Mouflon [32] Haemaphysalis sulcata Goat, mouflon [27,34] Hyalomma marginatum Sheep, swine [34,35] Ixodes ventalloi Cat [35] Rhipicephalus bursa Deer, sheep, goat [32,34] Rhipicephalus sanguineus s.l. Dog, fox, sheep [12,32,34] Rhipicephalus sanguineus Dog [27] Xenopsylla cheopis Fox [9] Ehrlichia spp. Amblyomma spp.…”

“…Mouflon [11] A. ovis Goat, mouflon [11] Anaplasma spp. Cattle, fox, goat [11] E. canis Deer, goat, sheep [32,34] Rickettsia spp. Cattle [91] Rhipicephalus sanguineus A. phagocytophilum Dog [13,96] A. platy Dog [29,30] E. canis Dog [27] R. conorii Dog, free life [49,55,56] R. conorii subsp.…”

“…were identified in Italy, once E. ovina in a tick collected from a healthy sheep [10], more often E. canis both in ticks and fleas and Candidatus Ehrlichia walkerii, found in I. ricinus only in the northernmost regions [12,16,23,33]. E. canis was more commonly found in Rhipicephalus [12,27,34,46], Haemaphysalis [27,32,33], Hyalomma [34] and Dermacentor [27,34]; only once in Ixodes ticks, namely in I. ventalloi collected from a cat [35]. Haemaphysalis ticks carry prevalently Ehrlichia and Anaplasma; the genus is not very common, more often found in South and insular Italy.…”

“…Ha. sulcata was found only in Sardinia and carries only two species: E. canis [27,34] and R. hoogstraalii [45,46]. Not frequently, Ehrlichia was found also in ticks non endemic in Italy, collected from migratory birds like Amblyomma spp.…”