Background: Ticks and tick-borne diseases are a major impediment to livestock production worldwide. Cattle trade and transnational transhumance create risks for the spread of ticks and tick-borne diseases and threaten cattle production in the absence of an effective tick control program. Few studies have been undertaken on cattle ticks in the Central African region; therefore, the need to assess the occurrence and the spatial distribution of tick vectors with the aim of establishing a baseline for monitoring future spread of tick borne-diseases in the region is urgent.Results: A total of 7091 ixodid ticks were collected during a countrywide cross-sectional field survey and identified using morphological criteria. Of these, 4210 (59.4%) ticks wereAmblyomma variegatum, 1112 (15.6%)Rhipicephalus(Boophilus)microplus, 708 (10.0%)Rhipicephalus(Boophilus)decoloratus, 28 (0.4%)Rhipicephalus(Boophilus)annulatus, 210 (3.0%)Hyalomma rufipes, 768 (10.8%)Hyalomma truncatum, and 19 (0.3%)Rhipicephalus sanguineus.Three ticks of the genusHyalommaspp. and 33 of the genusRhipicephalusspp. were not identified to the species level. Cytochromecoxidase subunit 1 (cox1) gene sequencing supported the data from morphological examination and led to identification of three additional species, namelyHyalomma dromedarii,Rhipicephalus sulcatusandRhipicephalus pusillus. The finding of the invasive tick speciesR. microplusin such large numbers and the apparent displacement of the indigenousR. decoloratusis highly significant sinceR. microplusis a highly efficient vector ofBabesia bovis.Conclusions: This study reports the occurrence and current geographical distribution of important tick vectors associated with cattle in Cameroon. It appears thatR. microplusis now well established and may be displacing nativeRhipicephalus(Boophilus) species, such asR. decoloratus. This calls for an urgent response to safeguard the livestock sector in western central Africa.

Ticks attach to and penetrate their hosts’ skin and inactivate multiple components of host responses in order to acquire a blood meal. Infestation loads with the cattle tick, Rhipicephalus microplus, are heritable: some breeds carry high loads of reproductively successful ticks, whereas in others, few ticks feed and reproduce efficiently. In order to elucidate the mechanisms that result in the different outcomes of infestations with cattle ticks, we examined global gene expression and inflammation induced by tick bites in skins from one resistant and one susceptible breed of cattle that underwent primary infestations with larvae and nymphs of R. microplus. We also examined the expression profiles of genes encoding secreted tick proteins that mediate parasitism in larvae and nymphs feeding on these breeds. Functional analyses of differentially expressed genes in the skin suggest that allergic contact-like dermatitis develops with ensuing production of IL-6, CXCL-8 and CCL-2 and is sustained by HMGB1, ISG15 and PKR, leading to expression of pro-inflammatory chemokines and cytokines that recruit granulocytes and T lymphocytes. Importantly, this response is delayed in susceptible hosts. Histopathological analyses of infested skins showed inflammatory reactions surrounding tick cement cones that enable attachment in both breeds, but in genetically tick-resistant bovines they destabilized the cone. The transcription data provided insights into tick-mediated activation of basophils, which have previously been shown to be a key to host resistance in model systems. Skin from tick-susceptible bovines expressed more transcripts encoding enzymes that detoxify tissues. Interestingly, these enzymes also produce volatile odoriferous compounds and, accordingly, skin rubbings from tick-susceptible bovines attracted significantly more tick larvae than rubbings from resistant hosts. Moreover, transcripts encoding secreted modulatory molecules by the tick were significantly more abundant in larval and in nymphal salivary glands from ticks feeding on susceptible bovines. Compared with tick-susceptible hosts, genes encoding enzymes producing volatile compounds exhibit significantly lower expression in resistant hosts, which may render them less attractive to larvae; resistant hosts expose ticks to an earlier inflammatory response, which in ticks is associated with significantly lower expression of genes encoding salivary proteins that suppress host immunity, inflammation and coagulation.

Background: The tick vectorRhipicephalus micropluswhich transmitsBabesiaspp. and rickettsial pathogens has not been reported in Kenya since 1998. More recently, the pathogenicBabesia bovishas been detected in cattle blood DNA. The status ofR. microplusin Kenya remains unknown. This study employed morphological and molecular tools to characterizeR. microplusoriginating from Kenya and assess the genetic relationships between Kenyan and other AfricanR. microplusgenotypes.Methods: Ticks were collected in south-eastern Kenya (Kwale County) from cattle and characterized to investigate the existence ofR. microplus. Genetic and phylogenetic relationships between the Kenyan and other annotatedR. microplusreference sequences was investigated by analysis of the cytochromecoxidase subunit 1 (cox1) gene. To further characterize Kenyan ticks, we generated low coverage whole genome sequences of twoR. microplus, oneR. decoloratusandR. appendiculatus. AB. bovisspecific TaqMan probe qPCR assay was used to detectB. bovisin gDNA fromR. microplusticks.Results: Occurrence ofR. micropluswas confirmed in Kwale County, Kenya. The KenyanR. microplus cox1 sequences showed very high pairwise identities (> 99%) and clustered very closely with reference AfricanR. microplussequences. We found a low genetic variation and lack of geographical sub-structuring among the Africancox1 sequences ofR. microplus. Four complete mitochondrial (mt) genomes for twoR. microplus, oneR. decoloratusand oneR. appendiculatuswere assembled from next generation sequence data. The mitochondrial genome sequences of the two KenyanR. microplusticks clustered closely with reference genome sequences from Brazil, USA, Cambodia and India formingR. microplusClade A. NoB. boviswas detected in the KwaleR. microplusDNA.Conclusions: These findings confirm the presence ofR. microplusin Kenya and suggest thatR. microplusClade A is prevalent in cattle in sub-Saharan Africa. These and other recent findings of widespread occurrence ofR. microplusin Africa provide a strong justification for urgent surveillance to determine and monitor the spread ofR. microplusand vector competence ofBoophilusticks forB. bovisin Africa, with the ultimate goal of strategic control.

African swine fever (ASF) is the most important disease constraining smallholder pig production in the Democratic Republic of Congo, causing high mortality in domestic pigs with severe impacts on the livelihoods of local populations. This study was conducted with the aim of determining the prevalence of ASF and circulating virus genotypes in asymptomatic pigs raised on smallholder farms in the South Kivu province to understand the transmission dynamics of ASF and ultimately improving disease control. A cross-sectional survey was carried out in 5 districts where 267 pig blood were screened for both antibody and viral genome using indirect Enzyme Linked Immunosorbent Assay (ELISA) and polymerase chain reaction (PCR) respectively. Additionally, amplicons from PCR positive samples were sequenced by Sanger method for genetic analysis of ASF virus (ASFV) based on the C-terminal region of the B646L gene that encodes the major capsid protein p72 and the gene E183L encoding the p54 protein. The overall seroprevalence obtained based on antibody to p30 protein was 37 % and was significantly higher (P < 0.05) in adult (>1 year) animals (44.7 %) than in younger ( 0.05) were observed when sex of the animal and breed were factored. PCR detection of ASFV amplified a specific band of expected size (257 bp) in 61 out of 267 blood samples, confirming the presence of the viral DNA in 22.8 % of asymptomatic domestic pigs. Statistical analysis revealed that ASFV infection in domestic pigs varied significantly (p < 0.001) according to geographical location and breed, with the highest infection rate found in Walungu district (33.7 %) while the lowest was registered in Kalehe (15.8 %). Local pigs (27.2 %) were more infected than crosses (9.2 %). Phylogenetic analyses based on partial sequences of the p72 and p54 genes revealed that all the ASFV detected belonged to genotype IX, which has previously been reported in other parts of DR Congo, and was clustered together with isolates from Kenya, Uganda and Republic of Congo. This study avails the first evidence of the presence of ASF virus in domestic pigs in the absence of outbreaks in South Kivu province, eastern DR Congo, indicating a need to raise awareness among pig farmers and veterinary authorities on the application of biosecurity measures and good husbandry practices to control the disease.

A meeting, sponsored by the Bill and Melinda Gates Foundation (BMGF) and organised by Clinglobal, was held at The International Livestock Research Institute (ILRI) in Nairobi, Kenya, from 19th – to 21st October 2022. The meeting assembled a unique group of experts on tick control in Africa. Academia, international agencies (FAO and ILRI), the private Animal Health sector and government veterinary services were represented. The significant outcomes included: (i) a shared commitment to standardisation and improvement of acaricide resistance bioassay protocols, particularly the widely used larval packet test (LPT); (ii) development of novel molecular assays for detecting acaricide resistance; (3) creation of platforms for disseminating acaricide resistance data to farmers, veterinary service providers and veterinary authorities to enable more rational evidence-based control of livestock ticks. Implementation of enhanced control will be facilitated by several recently established networks focused on control of parasites in Africa and globally, whose activities were presented at the meeting. These include a newly launched community of practice on management of livestock ticks, coordinated by FAO, an African module of the World Association for the Advancement of Veterinary Parasitology (WAAVP-AN) and the MAHABA (Managing Animal Health and Acaricides for a Better Africa) initiative of Elanco Animal Health. Graphical Abstract

African swine fever (ASF), caused by African swine fever virus (ASFV), is a severe haemorrhagic disease of pigs, outbreaks of which can have a devastating impact upon commercial and small-holder pig production. Pig production in western Kenya is characterised by low-input, free-range systems practised by poor farmers keeping between two and ten pigs. These farmers are particularly vulnerable to the catastrophic loss of livestock assets experienced in an ASF outbreak. This study wished to expand our understanding of ASFV epidemiology during a period when no outbreaks were reported. Two hundred and seventy six whole blood samples were analysed using two independent conventional and real time PCR assays to detect ASFV. Despite no recorded outbreak of clinical ASF during this time, virus was detected in 90/277 samples analysed by conventional PCR and 142/209 samples analysed by qPCR. Genotyping of a sub-set of these samples indicated that the viruses associated with the positive samples were classified within genotype IX and that these strains were therefore genetically similar to the virus associated with the 2006/2007 ASF outbreaks in Kenya. The detection of ASFV viral DNA in a relatively high number of pigs delivered for slaughter during a period with no reported outbreaks provides support for two hypotheses, which are not mutually exclusive: (1) that virus prevalence may be over-estimated by slaughter-slab sampling, relative to that prevailing in the wider pig population; (2) that sub-clinical, chronically infected or recovered pigs may be responsible for persistence of the virus in endemic areas.