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Autochthonous taurine and later introduced zebu cattle from Cameroon differ considerably in their resistance to endemic pathogens with little to no reports of the underlying genetic make-up. Breed history and habitat variations are reported to contribute significantly to this diversity worldwide, presumably in Cameroon as well, where locations diverge in climate, pasture, and prevalence of infectious agents. In order to investigate the genetic background, the genotypes of 685 individuals of different Cameroonian breeds were analysed by using the BovineSNP50v3 BeadChip. The variance components including heritability were estimated and genome-wide association studies (GWAS) were performed. Phenotypes were obtained by parasitological screening and categorised in Tick-borne pathogens (TBP), gastrointestinal nematodes (GIN), and onchocercosis (ONC). Estimated heritabilities were low for GIN and TBP (0.079 (se = 0.084) and 0.109 (se = 0.103) respectively) and moderate for ONC (0.216 (se = 0.094)). Further than revealing the quantitative nature of the traits, GWAS identified putative trait-associated genomic regions on five chromosomes, including the chromosomes 11 and 18 for GIN, 20 and 24 for TBP, and 12 for ONC. The results imply that breeding for resistant animals in the cattle population from Northern Cameroon might be possible for the studied pathogens; however, further research in this field using larger datasets will be required to improve the resistance towards pathogen infections, propose candidate genes or to infer biological pathways, as well as the genetic structures of African multi-breed populations.

Background: A better understanding of parasite population genetic processes in specific biogeography is needed to support onchocerciasis elimination goals. The genetic diversity of Onchocerca microfilariae was explored by amplifying a fragment of the 16S rRNA gene in the endemic area in Taraba State, Nigeria, Methods: Eight (8) communities were selected including six onchocerciasis endemic communities with records of ivermectin treatment having been annually distributed for 10 to 16 years, and two non-onchocerciasis endemic areas. The participants were 211 from endemic and 110 from non-endemic areas as control. Skin snips were taken from consenting participants by convenience sampling methods using a sterile sclera punch, from males and females residing within the communities for ten years and above or since birth, microfilaria and residual skin snips were preserved in RNALater® in a 1.5 ml micro-centrifuge tube. DNA was extracted from microfilariae recovered and from those in residual skin snip specimens. Polymerase Chain Reaction (PCR) amplification using specific primers for 16S genes was done to detect the identity of Onchocerca species. The amplified products were sequenced and analyzed for species identity. Results: Multiple sequence alignment and phylogenetic analysis results showed distinct diversity of two sample sequences (G49_O.v. Gashaka and Y02_O.v. Yorro) from other samples from the study area and other regions, indicating emergence of a new polymorphic strain of O. volvulus. Report of a preliminary case of emerging zoonosis of O. ochengi infection in human (skin snips) sample (O. ochengi G44) in this study. Conclusions: It is clear there is genetic diversity of Onchocerca species and emerging zoonosis in the study site. We suggest further investigation on the extent and potentials of emerging zoonotic onchocerciasis by O. ochengi, in the light of cattle, Simulium vectors, environmental and humans overlap in the study area.

Additional file 1. Reactivity and cross-reactivity of IgG in sera from Onchocerca-infected cattle and humans with O. ochengi and O. volvulus galectins and extracted proteins.

Additional file 2: Figure S2. Distribution of SNPs, InDels and breed-specific SNPs per chromosome and breed. Bar plot illustrates the number of SNPs found in at least two breeds (green), breed-specific SNPs (blue) and InDels (orange) across all the breeds for each chromosome.

Additional file 4: Figure S11. Distribution of SNPs per cattle breed of chromosome 23 between location 25,350,340 and 25,593,072 containing the BoLA gene. The X axis represents genomic location and y-axis represents ratio of non-reference base. Value 1 indicates that all reads carry the non-reference base at a given location whereas a value of 0.5 and 0 indicates half and none of the reads carry the non-reference base, respectively.

BACKGROUND: The Onchocerciasis Control Program (OCP) in West Africa has been closed down at the end of 2002. All subsequent control will be transferred to the participating countries and will almost entirely be based on periodic mass treatment with ivermectin. This makes the question whether elimination of infection or eradication of onchocerciasis can be achieved using this strategy of critical importance. This study was undertaken to explore this issue. METHODS: An empirical approach was adopted in which a comprehensive analysis was undertaken of available data on the impact of more than a decade of ivermectin treatment on onchocerciasis infection and transmission. Relevant entomological and epidemiological data from 14 river basins in the OCP and one basin in Cameroon were reviewed. Areas were distinguished by frequency of treatment (6-monthly or annually), endemicity level and additional control measures such as vector control. Assessment of results were in terms of epidemiological and entomological parameters, and as a measure of inputs, therapeutic and geographical coverage rates were used. RESULTS: In all of the river basins studied, ivermectin treatment sharply reduced prevalence and intensity of infection. Significant transmission, however, is still ongoing in some basins after 10-12 years of ivermectin treatment. In other basins, transmission may have been interrupted, but this needs to be confirmed by in-depth evaluations. In one mesoendemic basin, where 20 rounds of four-monthly treatment reduced prevalence of infection to levels as low as 2-3%, there was significant recrudescence of infection within a few years after interruption of treatment. CONCLUSIONS: Ivermectin treatment has been very successful in eliminating onchocerciasis as a public health problem. However, the results presented in this paper make it almost certain that repeated ivermectin mass treatment will not lead to the elimination of transmission of onchocerciasis from West Africa. Data on 6-monthly treatments are not sufficient to draw definitive conclusions.

Zecken-übertragene Pathogene gehören zu den schädlichsten Mikroorganismen, die für Verluste bei der Tierhaltung verantwortlich sind, mit einer erheblichen Bedrohung für die menschliche Bevölkerung. Ihr Nachweis mittels Blutausstrich oder Serologie erlaubt eher die Bestimmung einzelner Arten, während Ko-infektionen eher die Regel sind. Einschränkungen ergeben sich insbesondere in Laboren mit begrenzten Ressourcen und ohne nachhaltige Kapazität. Die vorliegende Arbeit beschäftigt sich mit der Identifizierung von 4 Gruppen von TBPs in Nordkamerun (Ehrlichien, Rickettsien, Spirochäten und Piroplasmen), wobei sieben Erstnachweise von Krankheitserregern in Rinderpopulationen (Borrelia theileri, Theileria mutans, T. velifera, Anaplasma platys, Anaplasma sp. ‘Hadesa’) in Kamerun sind, einschließlich den weltweiten Erstnachweisen von Rickettsia felis und Ehrlichia canis im Rind. Bei mehr als 80% (1123/1260, 89.1%) der untersuchten infizierten Rinder wurden mindestens zwei der vier untersuchten Genusgruppen (903/1123, 80.4%) von Krankheitserregern nachgewiesen, was die Einschränkung konventioneller Methoden unterstreicht. Über die Plattform eines kommerziellen Biochip-Anbieters (Chipron® in Berlin) wurde ein neuartiges Chip-basiertes Diagnostik-Array entwickelt. Dieses PCR-basierte Tool ermöglicht die gleichzeitige Identifizierung von fünf Erreger-Gattungen, einschließlich neuer Arten, im Blut mehrfach befallener Rinder. Deutlich mehr Krankheitserreger ließen sich so bei einer erhöhten Spezifität und Sensitivität nachweisen. Das LCD-Array kann problemlos in kleinen Veterinärlaboratorien in endemischen Ländern einschließlich Afrikas eingesetzt werden. Die häufigen Mischinfektionen mit je nach Region und Rinderrasse unterschiedlicher Zusammensetzung von Erregern werden zusätzlich von Umweltfaktoren beeinflusst (χ2, regression, p< 0,05). Unterschiedliche Reaktionen zwischen Individuen und Rassen aus derselben Umgebung motivierten den Test auf Heritabilität. Niedrige bis moderate (h_(obs.)^2=0.1 and h_(liab.)^2=0.6) Erbanlagen beobachtet, was eine genomische Grundlage für das Merkmal der Resistenz gegen Zecken-übertragene Pathogene darstellt. Dieses Ergebnis bestätigt die Möglichkeit einer Verbesserung der Resistenz durch Züchtung. Die genomweite Analyse erwies die quantitative Natur der Merkmale und verwies auf potentiell assoziierte genomische Regionen, von denen eine noch nicht in der Literatur beschrieben wurde. Erweiterte Analysen und eine größere Stichprobengröße wären nötig, um die Rinder Rassen besser zu charakterisieren (Feinkartierung von Lozi unter natürlicher Selektion und Allel-Fixierung). Les agents pathogènes transmis par les tiques comptent parmi les micro-organismes les plus nocifs responsables des pertes et de la détérioration des élevages, avec une menace importante pour la population humaine. Leur détection par frottis sanguin ou sérologie est plus susceptible de permettre l'identification d'espèces individuelle, alors que les co-infections sont plus fréquentes. Les contraintes sont tangibles dans les laboratoires aux ressources limitées et aux capacités non-durables. La présente thèse fait état de l'identification de sept agents pathogènes décris pour la première fois dans le cheptel bovin du Cameroun (Borrelia theileri, Theileria mutans, T. velifera, Anaplasma platys, Anaplasma sp. ‘Hadesa’) y compris ceux identifiés pour la première fois dans l'hôte bovin (Rickettsia felis et Ehrlichia canis). Plus de 80% de (1123/1260, 89.1%) la population infectée étudiée était co-infectée par au moins deux groupes des genres (903/1123, 80.4%) des agents pathogènes étudiés, ce qui souligne les limites des méthodes d'identification d'un seul agent pathogène précédemment utilisées. Sur la base de ces contraintes, une nouvelle matrice de diagnostic a été mise au point, grâce à la plate-forme du fournisseur commercial de biochip Chipron® à Berlin, en Allemagne. L'outil (LCD-array) basé sur la PCR a permis l'identification simultanée d'échantillons co-infectés, y compris les nouvelles espèces. Il a également permis d'identifier un plus grand nombre de microorganismes en état de co-infection avec une spécificité et une sensibilité accrues. Cet outil peut facilement être utilisé dans des laboratoires vétérinaires à capacité réduite dans les pays endémiques d'Afrique et d’ailleurs. Il a été démontré que la co-infection ainsi que la combinaison de pathogènes responsables diffèrent selon les zones climatiques et les populations bovines, influencées par des facteurs environnementaux (χ2, régression). Des réponses différentes entre individus et espèces (p< 0.05) d'un même environnement ont motivé le test des valeurs d'héritabilité. Des héritabilités faibles à modérées ont été décelées (h_(obs.)^2=0.1 and h_(liab.)^2=0.6), impliquant un fondement génétique du caractère de résistance. Ce résultat confirme la possibilité d'amélioration des facultés d’adaptation du bétail par gestion du système de production animale. Les analyses génétiques ont révélé les portions du génome responsables des phénotypes variés. Des analyses approfondies sur un plus grand échantillon seront nécessaires pour une différenciation des populations par représentation précise des loci sous sélection naturelle. Tick-borne pathogens are among the most harmful micro-organisms responsible for losses in animal husbandry, with a significant threat to the human population. Their detection by blood smear or serology is more likely to allow the identification of individual species, whereas co-infections are more common. Limitations arise especially in laboratories with limited resources and without sustainable capacities. The present thesis presents the identification of seven organisms in the cattle population from Cameroon for the first time (Borrelia theileri, Theileria mutans, T. velifera, Anaplasma platys, Anaplasma sp. ‘Hadesa’) including the first published reports of Rickettsia felis and Ehrlichia canis in cattle worldwide. More than 80% of the infected studied population (1123/1260, 89.1%) were found being co-infected with at least two of the four studied groups of genera (903/1123, 80.4%), highlighting the caveats of the predominating single pathogen identification approach. Based on those observed limitations, a novel chip-based diagnostic array was developed through the platform of the commercial biochip manufacturer Chipron® in Berlin, Germany. The PCR-based tool allowed the simultaneous identification of co-infected samples of five genera, including novel species. Moreover, the array allowed the identification of significantly more pathogens in co-infection with increased specificity and sensitivity compared to traditional Sanger sequencing. This LCD-array can be easily implemented in small veterinary laboratories in endemic countries of Africa and elsewhere. The co-infection status and pathogen combinations was proven to differ between climatic zones and cattle populations, and being influenced by environmental factors (χ2, regression). Different responses between individuals and breeds (p< 0.05) from the same environment motivated the test for heritability values. The observed low to moderate heritability based on genotyping dataset (h_(obs.)^2=0.1 and h_(liab.)^2=0.6) implied a genomic foundation of the trait of resistance to tick pathogens. More importantly, this result confirmed the possibility of improvement by breeding, which may be implemented as a control measure. The genome-wide analysis revealed the quantitative nature of the traits of resistance, exposing putative associated genomic regions with one of them not yet reported in the literature. Extended analyses and larger sample size will be advantageous for population differentiation and breed improvement through fine mapping of loci under natural selection and allele fixation related to resistance and susceptibility traits.