Invasive cattle ticks in East Africa: morphological and molecular confirmation of the presence of Rhipicephalus microplus in south-eastern Uganda

Abstract

Background: Rhipicephalus microplus, an invasive tick species of Asian origin and the main vector of Babesia species, is considered one of the most widespread ectoparasites of livestock. The tick has spread from its native habitats on translocated livestock to large parts of the tropical world, where it has replaced some of the local populations of Rhipicephalus decoloratus ticks. Although the tick was reported in Uganda 70 years ago, it has not been found in any subsequent surveys. This study was carried out to update the national tick species distribution on livestock in Uganda as a basis for tick and tick-borne disease control, with particular reference to R. microplus. Methods:The study was carried out in Kadungulu, Serere district, south-eastern Uganda, which is dominated by small scale livestock producers. All the ticks collected from 240 cattle from six villages were identified microscopically. Five R. microplus specimens were further processed for phylogenetic analysis and species confirmation. Results:The predominant tick species found on cattle was Rhipicephalus appendiculatus (86.9 %; n = 16,509). Other species found were Amblyomma variegatum (7.2 %; n = 1377), Rhipicephalus evertsi (2.3 %; n = 434) and R. microplus (3.6 %; n = 687). Phylogenetic analysis of the 12S rRNA, 16S rRNA and ITS2 gene sequences of R. microplus confirmed the morphological identification. Conclusions:It is concluded that R. microplus has replaced R. decoloratus in the sampled villages in Kadungulu sub-county, since the latter was not any longer found in this area. There is currently no livestock movement policy in force in Uganda, which could possibly limit the further spread of R. microplus ticks. Future surveys, but also retrospective surveys of museum specimens, will reveal the extent of distribution of R. microplus in Uganda and also for how long this tick has been present on livestock without being noticed. BackgroundThe Asian blue tick, Rhipicephalus (Boophilus) microplus (Canestrini, 1888), is one of the most important tick species infesting livestock in many parts of the world [1]. Rhipicephalus microplus has extended its distribution through the translocation of tick-infested cattle. In some regions in Africa, R. microplus has successfully competed and replaced the close related African blue tick, RhipicephalusThe authors wish to acknowledge the District Veterinary Officer of Serere District, Dr Amonya Collins for his help during tick collection. We also acknowledge the cattle owners and local council leaders of the six villages where this study was carried out for offering their cattle and helping with their restraint in this study. We are very grateful to for their help during tick collection and field tick identification to genus level. Ethics approval and consent to participateWritten informed consent was obtained from cattle owners. Cattle restraint, tick collection, 11 preservation, morphological and molecular analyses followed highest veterinary care and scientific standards as approved (SBLS/REC/16/136) by the

Molecular evidence confirms occurrence of Rhipicephalus microplus Clade A in Kenya and sub-Saharan Africa

“…Historically, R. microplus has been known to occur in East and South Africa since the second wave of cattle introduction into Africa following the rinderpest epidemic in 1896 when R. microplus-infested cattle were imported from southern Asia via Madagascar [2]. In the last decade it has been reported in many West African countries [3][4][5][6][7][8] and more recently in Angola [9], Cameroon [10] and Uganda [11].…”

Molecular evidence confirms occurrence of Rhipicephalus (Boophilus) microplus in Kenya and suggests that an undifferentiated genotype is prevalent in the African continent

“…The invasive Rhipicephalus Boophilus microplus, a highly e cient vector of tick fevers caused by Babesia bovis, Babesia bigemina, and Anaplasma marginale has rapidly spread into many African countries over the last decade [3][4][5][6][7][8][9][10][11]. In many areas, it has been reported to progressively displace, the indigenous R. decoloratus and R. annulatus [3,5,11,[32][33][34][35] sometimes establishing itself in areas predicted to be climatically unsuitable for its survival [7,32,35]. The latest ndings of widespread occurrence of R. microplus in eastern Uganda [11] and recent introduction and spread of the tick in Cameroon [10] have been attributed to uncontrolled live animal movements from neighbouring countries and cross-border animal trade.…”

“…In many areas, it has been reported to progressively displace, the indigenous R. decoloratus and R. annulatus [3,5,11,[32][33][34][35] sometimes establishing itself in areas predicted to be climatically unsuitable for its survival [7,32,35]. The latest ndings of widespread occurrence of R. microplus in eastern Uganda [11] and recent introduction and spread of the tick in Cameroon [10] have been attributed to uncontrolled live animal movements from neighbouring countries and cross-border animal trade.…”

“…decoloratus and Rhipicephalus evertsi evertsi. The increased dispersion and geographical spread of R. microplus into new areas in eastern and southern Africa has caused a displacement of the indigenous R. decoloratus [11,[32][33][34][35]. With the current invasion and spread of R. microplus into new regions in West, Central and East Africa, it is important to determine the current status of the two Babesia parasites in areas where the tick co-occur especially with the widespread displacement of the endemic R. decoloratus.…”

“…It was originally introduced into the African continent from southern Asia through Madagascar during the rinderpest epidemic in 1896 when R. microplus-infested cattle were imported into South Africa [2]. In the last decade it has been reported in many West African countries [3][4][5][6][7][8] and more recently in Angola [9], Cameroon [10] and Uganda [11].…”