Parasitology Division. National Veterinary Research Institute (NVRI), PMB 01 Vom, Plateau State, Nigeria.
Ticks Tick Borne Dis. 2021 Jul;12(4):101717. doi: 10.1016/j.ttbdis.2021.101717. Epub 2021 Mar 23.
Babesia rossi is the most pathogenic among the large canine babesias and it is the major cause of canine babesisosis in Nigeria. In South Africa it is transmitted by Haemaphysalis elliptica however, its putative vector in Nigeria where Rhipicephalus sanguineus is the most prevalent tick on dogs compared to Haemaphysalis species has not been ascertained. The incongruity between tick distribution and the frequent detection of B. rossi in Nigeria motivated this investigation to identify the local vector(s) of B. rossi. A total of 3805 ticks were collected from 363 naturally infested dogs from different parts of Nigeria. Of these numbers, 758 engorged female ticks; Rh. sanguineus (n = 660) and H. leachi (n = 98) were incubated for oviposition and hatching. After the completion of egg laying, Rh. sanguineus (n = 69) and H. leachi (n = 24) and their resulting progenies were screened for the presence of B. rossi DNA using a nested PCR targeting the 693 bp of the 18S rRNA gene of Babesia spp. Amplification and sequencing of B. rossi DNA was successful in the adults of H. leachi and their resulting egg and larval progenies but not in the adult Rh. sanguineus and progenies. The B. rossi DNA sequences from the H. leachi and their progenies have 99-100 % identity to each other and 98-99 % identical to sequences of B. rossi in GenBank (GenBank: MH143395.1), thus confirming transovarian passage. This evidence confirms for the first time following the reclassification of H. leachi to H. elliptica in South Africa the role of H. leachi in the transmission of B. rossi in dogs in Nigeria.
罗氏巴贝斯虫是大型犬巴贝斯虫中最具致病性的一种，也是尼日利亚犬巴贝斯虫病的主要病因。在南非，它是由椭圆革蜱传播的，但在尼日利亚，与哈氏血蜱相比，椭圆革蜱并不是犬身上最常见的蜱，其传播媒介尚未确定。蜱的分布与罗氏巴贝斯虫在尼日利亚频繁检出之间的不一致促使了这项研究，以确定罗氏巴贝斯虫的当地传播媒介。从尼日利亚不同地区的 363 只自然感染的犬身上共采集了 3805 只蜱。在这些数字中，有 758 只饱血雌性蜱；Rh. sanguineus（n = 660）和 H. leachi（n = 98）被孵育产卵和孵化。产卵完成后，用针对巴贝斯虫属的 18S rRNA 基因 693bp 的巢式 PCR 检测 Rh. sanguineus（n = 69）和 H. leachi（n = 24）及其后代中是否存在罗氏巴贝斯虫 DNA。在 H. leachi 的成虫及其后代的卵和幼虫中成功扩增和测序了罗氏巴贝斯虫 DNA，但在成年 Rh. sanguineus 和后代中未成功。从 H. leachi 及其后代中获得的罗氏巴贝斯虫 DNA 序列彼此之间的相似度为 99-100%，与 GenBank 中的罗氏巴贝斯虫序列（GenBank：MH143395.1）的相似度为 98-99%，因此确认了经卵传递。这一证据首次证实了 H. leachi 在南非被重新归类为 H. elliptica 后，在尼日利亚犬中传播罗氏巴贝斯虫的作用。
