Can Ixodus hexagonus ticks transmit pathogens to hedgehogs, causing the hedgehog to get sick?

Abstract

Hedgehogs and ticks from the species Ixodes hexagonus live in close contact with each other due to the fact that this tick species is a nest-dwelling species and hedgehogs built nests. As research conducted in the past will show, hedgehogs may play a role in acting as reservoir for several tick-borne pathogens. This type of research focuses on the role hedgehogs play in maintaining populations of this pathogen in the wild. It does not, however, look at the role that ticks play in causing disease in hedgehog. The aim of this paper is to find out whether ticks can transfer pathogens to hedgehogs, after which the pathogens cause the hedgehog to become ill. The way of doing this is by sending questionnaires out to proprietors of hedgehog sanctuaries, performing a pathological examination on a hedgehog that died naturally and by performing DNA extraction, PCR and RLB hybridization on adult female I. hexagonus ticks. The results from the questionnaires showed that most proprietors do not notice symptoms to be different from hedgehogs with ticks, versus hedgehogs without ticks. Most of the proprietors also indicated that they did not think hedgehogs can obtain pathogens from ticks. Symptoms that are seen most commonly in hedgehogs, regardless of having ticks, are coughing, locomotion problems, diarrhea, spinal loss, skin anomalies and apathy. Seven out of twelve (7/12) sanctuaries noted symptoms to be different in hedgehogs with ticks compared to hedgehogs without ticks, the incidence of apathy being higher in hedgehogs with ticks. What is noticeable from the questionnaire is the steady drop of hedgehogs that are brought to sanctuaries. The necropsy that was performed on a deceased hedgehog yielded results corresponding to lungworm infections. A total of 36 ticks were removed from the dead hedgehog, although there was no evidence that the hedgehog had died or even gotten ill from being bitten by the ticks. A factor causing these results to be less reliable is the fact that the corpse was fairly necrotic when it was presented to the pathology department. RLB hybridization showed positive results for six out of forty (6/40) ticks for the Ehrlichia/Anaplasma catch-all probe and one tick to be co-infected with Anaplasma marginale. Since the latter pathogen doesn’t occur in the Netherlands naturally, the reliability of the RLB results should be questioned. When looking at all the results it is still difficult to determine whether ticks actually contract disease from I. hexagonus ticks. One may argue that hedgehogs are like any other mammal, therefore being able to contract the same pathogens that many other mammals can contract. On the other hand, many tick-borne pathogens have been shown to possibly use the hedgehog as a reservoir for their natural population. A pathogen is unlikely to cause clinical symptoms in an animal it relies on to survive in the wild. In order to get more reliable results, more research has to be done.