Rangelia

(Rangelia vitalii)

Rangelia vitalii is a tick-borne haemoprotozoan which affects domestic and wild canids from South America and can be detected in neutrophils, monocytes, endothelial cells and erythrocytes as well as free in the plasma.

Distribution

Rangelia vitalii is spread in southern and south-eastern regions of Brazil, Uruguay, Argentina and recently, in Paraguay^[1]. It is transmitted by the tick Amblyomma aureolatum^[2].

Clinical signs

Dogs infected with R. vitalii may present intermittent fever, apathy, weight loss, hepatomegaly, splenomegaly, jaundice, generalized lymphadenopathy, hindlimb oedema, mucosal petechiae, haematemesis, and bloody diarrhoea. Typical clinical signs of canine rangeliosis include persistent bleeding from the nose (epistaxis), oral cavity, eyes and margins and lateral surface of the pinnae^[3]. The latter is considered a characteristic clinical sign of this disease.

Diagnosis

The diagnosis of rangeliosis is based on the history, clinical signs, haemogram, peripheral blood smear evaluation and response to therapy. Parasitic stages may be found in erythrocytes, monocytes, neutrophils or free in peripheral blood smears. PCR assays are also available for detecting R. vitalii DNA in blood samples^[3,4].

Treatment

The treatment of rangeliosis consists of off-label use of imidocarb dipropionate (6 mg/kg, IM). A second injection must be administered 15 days later^[3]. To avoid the cholinergic effects, it is important to administer atropine (0.05 mg/kg, SC) 30 minutes before the imidocarb dipropionate.

Control

Infection with R. vitalii should be prevented and controlled by using long-lasting acaricides with repellent activity against ticks (e.g., permethrin, flumethrin, and deltamethrin), in accordance with manufacturer’s instructions.

Public health considerations

None.

References

[1]  Inácio EL, Pérez-Macchi S, Alabi A, Bittencourt P, Müller A. Prevalence and molecular characterization of piroplasmids in domestic dogs from Paraguay. Ticks Tick Borne Dis. 2019;10:321-327.

[2]  Soares JF, Costa FB, Girotto-Soares A, Da Silva AS, França RT, Taniwaki SA, Dall’Agnol B, Reck J, Hagiwara MK, Labruna MB. Evaluation of the vector competence of six ixodid tick species for Rangelia vitalii (Apicomplexa, Piroplasmorida), the agent of canine rangeliosis. Ticks Tick Borne Dis. 2018;9:1221-1234.

[3]  França RT, Da Silva AS, Loretti AP, Mazzanti CM, Lopes ST. Canine rangeliosis due to Rangelia vitalii: from first report in Brazil in 1910 to current day – a review. Ticks Tick Borne Dis. 2014;5:466-74

[4]  Soares JF, Girotto A, Brandão PE, França, RT, Da Silva AS, Lopes STA, Labruna M. Detection and molecular characterization of a canine piroplasm from Brazil. Vet Parasitol. 2011;180:203-2088.