Résistance de la Tique Invasive Rhipicephalus (Boophilus) Microplus à la Nouvelle Gamme d’Acaricides Distribués en Côte d’Ivoire

Ce travail avait pour objectif d’améliorer la lutte contre la tique Rhipicephalus (Boophilus) microplus en Côte d’Ivoire en apportant une assistance aux éleveurs dans le choix des acaricides qui leur sont proposés. Pour ce faire, il a été question de répertorier les spécialités d’acaricides distribuées en Côte d’Ivoire pour le détiquage des bovins et par la suite, évaluer le niveau de résistance-sensibilité des tiques R. (B.) microplus à ces acaricides dans les élevages péri-urbains de bovins au sud de la Côte d’Ivoire, précisément dans la zone d’Azaguié où la tique exotique R. (B.) microplus a été découverte pour la première fois en Afrique de l’Ouest. Il ressort de l’étude que six (6) molécules acaricides sont officiellement distribuées en Côte d’Ivoire (Alphacyperméthrine, Cyperméthrine, Amitraz, Fluméthrine, Deltaméthrine et Fipronil) sous diverses appellations commerciales. Face aux échecs thérapeutiques recurents et aux plaintes des éleveurs, une nouvelle gamme d’acaricides est actuellement proposée aux éleveurs. Elle est essentiellement constituée de produits à base de fluméthrine, de fipronil, de deltaméthrine ou de cyperméthrine associée au chlorpyriphos, au butoxide de pipéronyl et à la citronnelle. La méthode de référence LPT (Larval Packet Test) standardisée par la FAO a été utilisée pour évaluer le niveau de résistance de cette tique invasive R. (B.) microplus à trois (3) molécules acaricides de cette gamme à savoir la deltaméthrine, la fluméthrine et la nouvelle spécialité de molécules associées (cyperméthrine-chlorpyriphos-citronnelle-butoxide de pipéronyl). Une variation du niveau de résistance a été signalée d’un acaricide à l’autre vis-à-vis des populations de tiques R. (B.) microplus testées. L’étude a montré une résistance des populations de tiques R. (B.) microplus à la deltaméthrine et à la fluméthrine. Quant à la nouvelle spécialité de molécules associées, elle a présenté un niveau de sensibilité acceptable exprimé par les populations de tiques R. (B.) microplus.   This work aimed to improve the fight against the tick Rhipicephalus (Boophilus) microplus in Côte d'Ivoire by providing assistance to breeders in the choice of acaricides marketed. To do this, the acaricides distributed in Côte d'Ivoire for cattle treatment was inventoried and then, the level of resistance- susceptibility of R. (B.) microplus to these acaricides was estimated in peri-urban cattle farms in southern Côte d'Ivoire, precisely in the area of Azaguié where the exotic tick R. (B.) microplus was discovered for the first time in West Africa. It appears from the study that six (6) acaricidal molecules are officially distributed in Côte d'Ivoire (Alphacypermethrin, Cypermethrin, Amitraz, Flumethrin, Deltamethrin and Fipronil) under various trade names. Faced with recurrent treatment failures and complaints from breeders, a new range of acaricides is currently being offered to breeders. It essentially consists of products based on flumethrin, fipronil, deltamethrin or cypermethrin associated with chlorpyrifos, piperonyl butoxid and citronella. The reference method LPT (Larval Packet Test) standardized by the FAO was used to estimate the level of resistance of the invasive tick R. (B.) microplus to three (3) acaricides, namely deltamethrin, flumethrin and the new product of associated acaricides (cypermethrin-chlorpyrifos-piperonyl butoxid- citronella). A variation of the resistance of R. (B.) microplus has been reported from one acaricide to another. The study showed a resistance of R. (B.) microplus tick populations to deltamethrin and flumethrin. However, an acceptable level of susceptibility expressed by the population ticks of R. (B.) microplus to the association of acaricides (cypermethrin-chlorpyrifos-piperonyl butoxid-citronella) was reported

Résistance de la Tique Invasive Rhipicephalus (Boophilus) Microplus à la Nouvelle Gamme d’Acaricides Distribués en Côte d’Ivoire

Ce travail avait pour objectif d’améliorer la lutte contre la tique Rhipicephalus (Boophilus) microplus en Côte d’Ivoire en apportant une assistance aux éleveurs dans le choix des acaricides qui leur sont proposés. Pour ce faire, il a été question de répertorier les spécialités d’acaricides distribuées en Côte d’Ivoire pour le détiquage des bovins et par la suite, évaluer le niveau de résistance-sensibilité des tiques R. (B.) microplus à ces acaricides dans les élevages péri-urbains de bovins au sud de la Côte d’Ivoire, précisément dans la zone d’Azaguié où la tique exotique R. (B.) microplus a été découverte pour la première fois en Afrique de l’Ouest. Il ressort de l’étude que six (6) molécules acaricides sont officiellement distribuées en Côte d’Ivoire (Alphacyperméthrine, Cyperméthrine, Amitraz, Fluméthrine, Deltaméthrine et Fipronil) sous diverses appellations commerciales. Face aux échecs thérapeutiques recurents et aux plaintes des éleveurs, une nouvelle gamme d’acaricides est actuellement proposée aux éleveurs. Elle est essentiellement constituée de produits à base de fluméthrine, de fipronil, de deltaméthrine ou de cyperméthrine associée au chlorpyriphos, au butoxide de pipéronyl et à la citronnelle. La méthode de référence LPT (Larval Packet Test) standardisée par la FAO a été utilisée pour évaluer le niveau de résistance de cette tique invasive R. (B.) microplus à trois (3) molécules acaricides de cette gamme à savoir la deltaméthrine, la fluméthrine et la nouvelle spécialité de molécules associées (cyperméthrine-chlorpyriphos-citronnelle-butoxide de pipéronyl). Une variation du niveau de résistance a été signalée d’un acaricide à l’autre vis-à-vis des populations de tiques R. (B.) microplus testées. L’étude a montré une résistance des populations de tiques R. (B.) microplus à la deltaméthrine et à la fluméthrine. Quant à la nouvelle spécialité de molécules associées, elle a présenté un niveau de sensibilité acceptable exprimé par les populations de tiques R. (B.) microplus.   This work aimed to improve the fight against the tick Rhipicephalus (Boophilus) microplus in Côte d'Ivoire by providing assistance to breeders in the choice of acaricides marketed. To do this, the acaricides distributed in Côte d'Ivoire for cattle treatment was inventoried and then, the level of resistance- susceptibility of R. (B.) microplus to these acaricides was estimated in peri-urban cattle farms in southern Côte d'Ivoire, precisely in the area of Azaguié where the exotic tick R. (B.) microplus was discovered for the first time in West Africa. It appears from the study that six (6) acaricidal molecules are officially distributed in Côte d'Ivoire (Alphacypermethrin, Cypermethrin, Amitraz, Flumethrin, Deltamethrin and Fipronil) under various trade names. Faced with recurrent treatment failures and complaints from breeders, a new range of acaricides is currently being offered to breeders. It essentially consists of products based on flumethrin, fipronil, deltamethrin or cypermethrin associated with chlorpyrifos, piperonyl butoxid and citronella. The reference method LPT (Larval Packet Test) standardized by the FAO was used to estimate the level of resistance of the invasive tick R. (B.) microplus to three (3) acaricides, namely deltamethrin, flumethrin and the new product of associated acaricides (cypermethrin-chlorpyrifos-piperonyl butoxid- citronella). A variation of the resistance of R. (B.) microplus has been reported from one acaricide to another. The study showed a resistance of R. (B.) microplus tick populations to deltamethrin and flumethrin. However, an acceptable level of susceptibility expressed by the population ticks of R. (B.) microplus to the association of acaricides (cypermethrin-chlorpyrifos-piperonyl butoxid-citronella) was reported

Cattle ticks and associated tick-borne pathogens in Burkina Faso and Benin: Apparent northern spread of Rhipicephalus microplus in Benin and first evidence of Theileria velifera and Theileria annulata

peer reviewedBabesiosis, theileriosis, anaplasmosis, and heartwater are tick-borne diseases that threaten livestock production in sub-Saharan Africa including Burkina Faso and Benin. For over a decade, these two bordering countries have been facing an invasion of the livestock by the tick Rhipicephalus microplus, a major vector for babesiosis, accidentally introduced in Benin in 2004. The molecular identification of tick-borne pathogens in this border area is of particular interest due to animals seasonal migration between the two countries. In this survey, epidemiological features of ticks and tick-borne pathogens in cattle were investigated to compare the eastern Burkina Faso, corresponding to a seasonal migration departure zone, and the northern Benin, which represents a seasonal migration arrival zone. Ticks and peripheral blood were collected from a total of 946 cattle in the two areas. Ticks were morphologically identified and the DNA samples from bovine blood and ticks were analysed by Reverse Line Blot (RLB) hybridization process. A total of 2856 ticks were collected on 490 cattle in Burkina Faso, eight tick species were identified, while 3583 ticks were collected on 456 cattle in North Benin with nine tick species identified. The invasive tick, R. microplus was not found in eastern Burkina Faso, but its spread farthest north in Benin is reported. Six tick-borne pathogen species were found in cattle blood both in eastern Burkina Faso and in northern Benin. Ranked in decreasing order of overall prevalences, they are: Theileria mutans (91.1%), Theileria velifera (77.8%), Babesia bigemina (10.9%), Anaplasma marginale (4.2%), Babesia bovis (3.3%), and Theileria annulata (1.8%). To the best of our knowledge, this survey represents the first report of T. velifera and T. annulata in the region. Overall, the TBP prevalences were significantly higher in northern Benin than in eastern Burkina Faso, indicating a higher parasitological risk in this area. © 2021 Elsevier Gmb

Cross border transhumance involvement in ticks and tick-borne pathogens dissemination and first evidence of Anaplasma centrale in Burkina Faso

In West Africa, cross-border transhumance, also called seasonal migration, is known to be a very important animal production strategy, as it involves about 70 to 90% of cattle. In spite of the cattle movements, some strategic areas of transhumance remain poorly explored regarding ticks and their associated pathogens investigations. The purpose of this study is to evaluate the involvement of transhumance in the spread of cattle ticks and associated pathogens in Burkina Faso (BF) and Benin (BN), in a context of speedy invasion of West African livestock by Rhipicephalus microplus. A longitudinal survey was performed on 210 cattle from BF, monitored for ticks and tick-borne pathogens (TBP) during one seasonal transhumance. The first sampling coded “T0BF” took place in eastern BF, at the transhumance departure. A second sampling “T1BN” was carried out in northern BN, the transhumance arrival zone. A third sampling “T2BF” was done at the return of cattle in eastern BF. Ticks were morphologically identified and TBP detected with reverse line blot hybridization (RLB) assay. A total of 1027 ticks (7 species), 1006 ticks (11 species) and 1211 ticks (9 species) were respectively found at T0BF, T1BN and T2BF. Some species were collected at the three times of sampling without any significant difference in their relative abundances. However, other tick species appeared only at T1BN and/or T2BF. The TBP species found at the three points surveyed were Theileria annulata, Theileria mutans, Theileria velifera, Babesia bigemina and Anaplasma marginale. The most prevalent was T. mutans with 166/210 (79%), 159/210 (75.7%) and 78/210 (37%) cattle positive respectively at T0BF, T1BN and T2BF. Anaplasma centrale was evidenced with 0.5% and 0.9% respectively at T0BF and T2BF. To our knowledge, this represents its first report in the study area. Overall, the TBP prevalences were significantly lower at T2BF, highlighting the effect of tick populations changes induced by transhumance combined with the seasonal variation influence. © 202

Epidemiology of peste des petits ruminants virus in West Africa: Is lineage IV replacing lineage II in Burkina Faso?

Objective This study aimed at investigating the lineages of peste des petits ruminants virus (PPRv) currently circulating in Burkina Faso. Methods As part of the PPR surveillance from 2021 to 2022 in Cascades, Centre Ouest and Plateau central regions of Burkina Faso, outbreak investigations were carried out. We collected swab samples from eyes, mouth and nose from suspicious goats and sheep after confirmation of PPR through a rapid diagnostic test. Tissue samples (spleen, lung, lymph nodes) of suspicious dead animals were also collected. Virus confirmation was performed with RT-PCR amplification targeting nucleocapsid (N) gene. The RT-PCR products of positives extracts were sequenced in both forward and reverse sense. Sequence analysis, including pairwise alignment and BLAST algorithm application on GenBank were used to determine the lineages within our samples. Results In total, nine outbreaks were recorded in the three studied regions during the investigation. The outbreak investigation found 21 small ruminants positive to PPRv out of the 39 (53.84%) analysed. The sequences of samples from the three regions have at least 95% (333/350 bp) of similarity with lineages IV samples from Nigeria (MN725768) and Cameroon (MH447978). The same percentage of similarity was also obtained with the lineage IV sequence from Niger but on lower sequence size: i.e. 222/234 bp. Pairwise alignment with lineages I and II from Burkina Faso published in previous work showed no significant similarity or no more than 87% of similarity on smaller sequences (i.e. 188/218 bp). To our knowledge, this is the first time that lineage IV of PPRv is identified in Burkina Faso. Even though the results of this study are based on sequences of around 300 bp only, they suggest that the expansion of PPRv lineage IV in West Africa which started in Nigeria and has now spread to Burkina Faso after occurring also in Niger and Mali. Hence, further investigations are needed to better understand how the lineage IV has spread toto non-neighbouring regions in Burkina Faso and seems to have replaced lineage II of PPRv. Conclusion This study confirms the presence of the PPRv lineage IV in Burkina Faso. Based on outbreaks investigated, this lineage seems to have replaced lineage II. Further investigations are thus needed to better understand how PPRv lineage spread in the region and if lineage II is still present and what the implications for PPR control are

The potential of Rhipicephalus microplus as a vector of Ehrlichia ruminantium in West Africa

Heartwater, or cowdriosis, is a virulent tick-borne rickettsial disease of ruminants caused by Ehrlichia ruminantium, biologically transmitted by Amblyomma species (A. variegatum in West Africa). In West Africa, this bacterium was recently reported to naturally infect the invasive cattle tick, Rhipicephalus microplus (Rm) through trans-ovarian transmission from replete adult females to offspring. A ‘sheep-tick-sheep’ cycle was set up to determine whether feeding the progeny of these ticks on naïve sheep could lead to infection, and to compare clinical outcomes resulting from this transmission with those observed following infection by the natural A. variegatum (Av) vector. Using local strains of ticks (KIMINI-Rm and KIMINI-Av) and of E. ruminantium (BK242), we recorded, using the PCR technique, the presence of bacterial DNA in ticks (larvae for Av and females for Rm) engorged on sheep inoculated by BK242-infected blood. The bacterial DNA was also detected in the next stages of the lifecycle of R. microplus (eggs and larvae), and in sheep infested either by those R. microplus larvae or by A. variegatum nymphs moulted from larvae engorged on blood-inoculated sheep. Bacterial infection in these sheep was demonstrated by detecting antibodies to E. ruminantium using the MAP1-B ELISA and by isolation of the bacterium on cell culture from blood. The sequences of PCS20 gene detected in ticks and sheep were identical to that of the BK242 strain. Our results confirm that R. microplus can acquire and transmit E. ruminantium to the next stage. However, this transmission resulted in a mild subclinical disease whereas severe clinical disease was observed in sheep infested by A. variegatum infected nymphs, suggesting differences in the tick/bacteria relationship. Future studies will focus on replicating these findings with ticks of different isolates and life stages to determine if R. microplus is playing a role in the epidemiology of heartwater in West Africa. Additionally, studies will investigate whether sheep that are seropositive due to infestation by E. ruminantium-infected R. microplus are subsequently protected against heartwater. Such data will add to our understanding of the possible impact of R. microplus in areas where it has become recently established

Efficacy of two commercial synthetic pyrethroids (cypermethrin and deltamethrin) on Amblyomma variegatum and Rhipicephalus microplus strains of the south-western region of Burkina Faso

Since 2011, period of the livestock invasion by the cattle tick Rhipicephalus microplus in Burkina Faso (BF), tick-control problems were exacerbated. Based on farmer’s reports, most commonly used commercial acaricides were found to be ineffective in Western South part of the country. To investigate the occurrence and extent of such acaricidal ineffectiveness, we performed the standardized larval packet test (LPT) with commercial deltamethrin (vectocid) and cypermethrin (cypertop), on two cattle tick species, the native Amblyomma variegatum and the invasive R. microplus. The resistance ratios (RR) were computed with susceptible Hounde strain of Rhipicephalus geigyi as reference. The R. microplus population showed resistance to the two acaricides tested with the highest lethal concentration (LC) values, and different resistance ratios higher than 4 (deltamethrin: RR50 = 28.18 and RR90 = 32.41; cypermethrin: RR50 = 8.79 and RR90 = 23.15). In the contrary, A. variegatum population was found to be highly susceptible to acaricides tested with low lethal concentrations and resistance ratio values (deltamethrin: RR50 = 0.5 and RR90 = 0.48; cypermethrin: RR50 = 0.68 and RR90 = 0.79). These data demonstrate high synthetic pyrethroid resistance in R. microplus strain, leading to conclude that the acaricide ineffectiveness in tick populations control remains a concern in BF. © 2021, The Author(s)