The transmission of Theileria annulata to a rabbit by the larvae of the tick Hyalomma rufipes

Abstract

SummaryA New Zealand White rabbit on which larvae of Hyalomma rufipes were fed died of theileriosis due to Theileria annulata 22 days after the larvae had fed. The larvae were direct progeny of an enorged female collected from trade cattle in the veterinary control post at Ibadan. The danger attending the feeding on rabbits of first progeny of ticks collected from cattle in countries where some tick-borne diseases are endemic is highlighted. The possibility of transovarial transmission of Theileria is discussed.Rabbits are commonly used for rearing different species of ticks in many laboratories in the world. The ears of this laboratory animal possess a large surface and are endowed with abundant superficial veins through which ticks obtain their blood meal. Furthermore, the rabbit is believed to be refractory to most of the diseases transmitted by ticks to domestic animals. In this paper we report a case of transmission of Theileria annlllata to a rabbit by the larvae derived from an engorged female Hyalomma mfipes which was collected frolll trade cattle. Materials and MethodsIn the course of establishing laboratory colonies of the ticks found commonly on Nigerian livestock, engorged females of some tick species were collected from the trade cattle kept in the veterinary control post at Ibadan. An engorged female of H. rufipes collected in this way laid eggs 30 days afterwards. The larvae were fed on a New Zealand White rabbit according to the method described by Bailey (1960) with 300 larvae in each earbag (total 600 larvae). Before the larvae were applied, smears were made from the blood of the rabbit, stained with Giemsa stain and examined for the presence of blood parasites. 12 days later, 389 larvae had fed and dropped and were removed from the rabbit's ears. The nymphs which moulted from these larvae were fed on another New Zeland White rabbit and smears were made from its blood before and after the nymphs were fed. The same procedure was adopted for the rabbit on which the adults which moulted from the nymph had fed. Observations and resultsThe blood smears made from the rabbit before the larvae were fed were negative for blood parasites. However, the rabbit was observed to be in a state of depression and developed a high temperature (41°C) 20 days after the fed larvae were removed. It died 2 days later. Blood smears made immediately after death and stained with Giemsa stain showed about 20% of the rabbit's erythrocytes to be infected with the predominantly round to oval, ring-like piroplasms typical of T. annlllata. Postmorten examination was performed on the rabbit and the findings conformed to the pathological syndromes (Barnett, 1968) of infection with T.annlliata. The spleen, liver and the superficial lymph nodes were greatly enlarged and the lungs were oedematous and congested. Giemsa-stained smears from the swollen lymph nodes and the spleen showed a moderate number of schizonts. The smears made from the blood of the rabbits on which the nymphs and adults had fed were negative for blood parasites....

Laboratory rearing of Theileria annulata-free Hyalomma anatolicum anatolicum ticks

“…The absence of transovarial transmission of T. annulata by the H. a. anatolicum might be the reason behind it. Although a report (Dipeolu and Ogunji 1977), generally the rabbits are considered as non-susceptible host for T. annulata infection (Bhattacharyulu et al 1975). Though properly screened T. annulata infection free cross bred calves were used in the experiment for feeding of adult H. a. anatolicum, the possibility of getting infection through the ticks present in green fodder can not be ruled out.…”

Blood Parasites Affects Local Rabbits in Iraq, a Review

“…The second study Athraa, (2014) who study the prevalence of gastrointestinal and blood parasites with some histopathological changes of local rabbits in Baghdad province ,who found some species of blood protozoa that infect local rabbits ,that the total infection rate of blood protozoa (38%) included (Thieleria , Babesia, Anaplasma and Plasmodium) in the percentage (23.75,5,6.25 and 25) respectively. Dipeolu and Ogunji (1977). In their study of the transfer of Theileria annulata to a rabbit by the larvae of the tick Hyalomma rufipes they found a white rabbit from New Zealand on which larvae of Hyalomma rufipes were fed died of theileriosis because of Theileria annulata 22 days after the larvae had fed rufipes since its blood was free of Theileria parasites before the larvae were fed ; .…”

Oriental Theileriosis

“…Ticks that ingest erythrocytes infected with piroplasms transmit the parasite when they moult to the next instar [115]. Transovarial transmission, parasite transmission from adult female to the next generation of eggs, has yet to be scientifically demonstrated [103] by any transmission studies although some researchers have speculated that Theileria might involve transovarial transmission in ticks [116,117].…”