Detection of a Larva of Armillifer armillatus in a Potto (Perodicticus potto) from the Republic of the Congo.

We determined the complete sequence of the mitochondrial DNA (mtDNA) of a parasite discovered between the subcutaneous tissue and the peritoneum of an African nocturnal non-human primate (NHP). The parasite and host sequences were obtained by a combination of Sanger sequencing and nanopore MinION techniques. Analyses of mtDNA gene arrangements and sequences unambiguously showed that the parasite investigated was the pentastomid Armillifer armillatus, also commonly named the tongue worm. The full-length mitochondrial genome of A. armillatus, measuring 16,706 bp in length, contains 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes, an arrangement identical to that of previously described pentastomid mitochondrial genomes. We describe here the second full mitochondrial genome of A. armillatus to date. To identify the NHP host, maximum likelihood phylogenetic analyses of a 441-bp fragment on the 12S rDNA gene and of a 1,140-bp fragment of the mitochondrial cytochrome b strongly support clustering with the African lorisid Perodicticus potto, a species that has rarely been reported as an intermediate host of this parasite.

Detection of DNA of filariae closely related to Mansonella perstans in faecal samples from wild non-human primates from Cameroon and Gabon.

BACKGROUND: The Onchocercidae is a family of filarial nematodes with several species of medical or veterinary importance. Microfilariae are found in the blood and/or the dermis and are usually diagnosed in humans by microscopy examination of a blood sample or skin biopsy. The main objectives of this study were to evaluate whether filariae DNA can be detected in faecal samples of wild non-human primates (NHPs), whether the detected parasites were closely related to those infecting humans and whether filarial DNA detection in faeces is associated with co-infections with nematodes (Oesophagostumum sp. and Necator sp.) known to cause blood loss while feeding on the host intestinal mucosa. METHODS: A total of 315 faecal samples from 6 species of NHPs from Cameroon and Gabon were analysed. PCRs targeted DNA fragments of cox1 and 12S rDNA genes, to detect the presence of filariae, and the internal transcribed spacer 2 (ITS2), to detect the presence of Oesophagostomum sp. and Necator sp. infections. RESULTS: Among the 315 samples analysed, 121 produced sequences with > 90% homology with Onchocercidae reference sequences. However, 63% of the 12S rDNA and 78% of the cox1 gene sequences were exploitable for phylogenetic analyses and the amplification of the 12S rDNA gene showed less discriminating power than the amplification of the cox1 fragment. Phylogenetic analyses showed that the cox1 sequences obtained from five chimpanzee DNA faecal samples from Gabon and two from Cameroon cluster together with Mansonella perstans with high bootstrap support. Most of the remaining sequences clustered together within the genus Mansonella, but the species could not be resolved. Among the NHP species investigated, a significant association between filarial DNA detection and Oesophagostomum sp. and Necator sp. infection was observed only in gorillas. CONCLUSIONS: To our knowledge, this is the first study reporting DNA from Mansonella spp. in faecal samples. Our results raise questions about the diversity and abundance of these parasites in wildlife, their role as sylvatic reservoirs and their potential for zoonotic transmission. Future studies should focus on detecting variants circulating in both human and NHPs, and improve the molecular information to resolve or support taxonomy classification based on morphological descriptions.

Effects of an injectable long-acting formulation of ivermectin on Onchocerca ochengi in zebu cattle.

The availability of a safe macrofilaricidal drug would help to accelerate onchocerciasis elimination. A trial was conducted in Cameroon to evaluate the effects of a subcutaneous injectable long-acting formulation of ivermectin (LAFI) on the microfilariae (mf) and adult stages of Onchocerca ochengi. Ten zebu cattle naturally infected with the parasite were injected subcutaneously with either 500 mg (group A, N = 4), or 1000 mg long-acting ivermectin (group B, N = 4) or the vehicle (group C, N = 2). Skin samples were collected from each animal before, and 6, 12, and 24 months after treatment to measure microfilarial densities (MFDs). Nodules excised before, and 6 and 12 months after treatment were examined histologically to assess the adult worms' viability and reproductive status. Blood samples were collected at pre-determined time-points to obtain pharmacokinetic data. Before treatment, the average O. ochengi MFDs were similar in the three groups. Six months after treatment, all animals in groups A and B were free of skin mf, whereas those in group C still showed high MFDs (mean = 324.5 mf/g). Only one ivermectin-treated animal (belonging to group A) had skin mf 12 months after treatment (0.9 mf/g). At 24 months, another animal in group A showed skin mf (10.0 mf/g). The histologic examination of nodules at 6 and 12 months showed that LAFI was not macrofilaricidal but had a strong effect on embryogenesis. The new LAFI regimen might be an additional tool to accelerate the elimination of human onchocerciasis in specific settings.

TITLE: Effets d'une formulation injectable d'ivermectine à activité prolongée sur Onchocerca ochengi chez les bovins zébu. ABSTRACT: La disponibilité d'un médicament macrofilaricide et sans danger permettrait d'accélérer l'élimination de l'onchocercose. Un essai a été mené au Cameroun pour évaluer les effets d'une formulation injectable en sous-cutané d'ivermectine à activité prolongée (FIAP) sur les microfilaires (mf) et les stades adultes d'Onchocerca ochengi. Dix vaches zébu infectées naturellement par le parasite ont reçu une injection sous-cutanée de 500 mg (groupe A, N = 4) ou de 1000 mg d'ivermectine à activité prolongée (groupe B, N = 4) ou le véhicule (groupe C, N = 2). Des échantillons de peau ont été collectés de chaque animal avant, puis 6, 12 et 24 mois après traitement pour mesurer les densités microfilariennes (DMF). Des nodules prélevés avant et 6 et 12 mois après traitement ont été examinés histologiquement pour évaluer la viabilité et le statut reproductif des vers adultes. Des échantillons de sang ont été prélevés pour obtenir des données de pharmacocinétique. Avant traitement, les DMF à O. ochengi étaient similaires dans les 3 groupes. Six mois après traitement, aucun des animaux des groupes A et B ne présentait de mf dermiques, alors que ceux du groupe C présentaient encore des DMF élevées (moyenne : 324,5 mf/g). Parmi les animaux traités par ivermectine, un seul (du groupe A) avait des mf dermiques 12 mois après traitement (0,9 mf/g). A 24 mois, un autre animal du groupe A avait des mf (10,0 mf/g). L'examen histologique des nodules collectés à 6 et 12 mois montrait que la FIAP n'était pas macrofilaricide mais avait un effet marqué sur l'embryogénèse. La nouvelle FIAP pourrait représenter un outil pour accélérer l'élimination de l'onchocercose dans certaines circonstances spécifiques.