Babesia lengau associated with cerebral and haemolytic babesiosis in two domestic cats

Abstract

Background: Although reported sporadically from various countries, feline babesiosis appears to be a significant clinical entity only in South Africa, where Babesia felis is usually incriminated as the causative agent. Babesia lengau, recently described from asymptomatic cheetahs, has now possibly been incriminated as the causative agent in two severe clinical cases in domestic cats.

Findings: Both cats were euthanised in extremis. While typical feline babesiosis in South Africa is an afebrile disease with a chronic manifestation, there was acute onset of severe clinical signs in both cats and their body temperatures were above the normal range when they were presented for treatment. Haemolytic anaemia was confirmed in one case. To our knowledge, this is the first report of cerebral babesiosis in cats.On reverse line blot 18S rDNA PCR products obtained from both cats showed positive hybridization profiles with the B. lengau species-specific probe. The two partial parasite 18S rRNA gene sequences obtained, showed high sequence similarity (99.9%) to B. lengau. In a representative tree constructed by the neighbor-joining method using the two-parameter model of Kimura the two obtained partial 18S rDNA sequences and that of B. lengau formed a monophyletic group with B. conradae and sequences previously isolated from humans and wildlife in the western USA.

Conclusion: All clinical cases of feline babesiosis in South Africa are not necessarily caused by B. felis. Other piroplasms, e.g. B. lengau, may be incriminated in clinical cases, especially those occurring outside the known endemic area.

Figure 1

Map of South Africa, showing the localities of the two cases. The feline babesiosis endemic area extends along the eastern and southern coast (KwaZulu-Natal, Eastern and Western Cape Provinces), as well as along the eastern escarpment in Mpumalanga and Limpopo Provinces in the north-eastern part of the country. Case 1 (Rustenburg): Open circle. Care 2 (Wellington): Black circle.

Figure 2

The brain of the cat (Case 2): The entire brain shows pronounced congestion with clear red-pink discoloration of the grey matter, as well as multifocal petechiae (Photograph: Tertius Gous).

Figure 3

Brain smear (Diff Quick stain) (Case 2): Cerebral capillary sludging of red blood cells that are heavily parasitized by a large Babesia (x1000) The dark, purple-bluish spots seen on the photograph represent the parasite in the erythrocyte (Photograph: Tertius Gous).

Figure 4

Results of the neighbor-joining analysis of the 18S rRNA gene of the two piroplasms: The phylogenetic relationship of the piroplasms involved in cases 1 and 2 with other Babesiaand Theileria species is shown. The scale bar represents the % nucleotide differences.