Bovine onchocercosis in North Cameroon

Wahl, G.; Achukwi, Mbunkah Daniel; Mbah, D.A.; Dawa, O.; Renz, Alfons

doi:10.1016/0304-4017(94)90121-x

Cited by 55 publications

(57 citation statements)

References 15 publications

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“…The cattle population in the study area was estimated to be higher than that of humans in the locality by a factor of about 15. The higher infection of the flies with O. ochengi as compared to O. volvulus may be due to the fact that most of the cattle carry O. ochengi infections as described earlier by Wahl et al [27], providing the more accessible and main source of blood meals for the vectors. Low O. volvulus infection rates (17%) in humans in the locality [28] may also be a contributing factor to the low transmission rates of human onchocerciasis.…”

Section: Discussionmentioning

confidence: 73%

“…After 6 and 24 hours of incubation (the medium was recovered and replenished once in between), the biopsies were blotted dry and weighed (the range was 20-50 mg for all three skin snips). Thereafter, to recover the microfilariae that had not emerged from the biopsies during incubation, the skin biopsies were digested with 0.5% (w/v) Type VII collagenase (Sigma, St. Louis, USA) at 32 o C. The microfilariae were morphologically identified and distinguished using the procedure of Wahl et al [27] with respect to their species and counted under a dissecting microscope at 50× magnification. A compound microscope was used for confirmation of identification when necessary.…”

Section: Cattle Skin Microfilariaementioning

confidence: 99%

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Onchocerca ochengitransmission dynamics and the correlation ofO. ochengimicrofilaria density in cattle with the transmission potential

2000

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-The intensity of natural transmission of Onchocerca ochengi and Onchocerca volvulusby anthropo-boophilic Simulium damnosum s.l. was studied longitudinally in two cattle watering sites of a cattle ranch within a predominantly cattle populated area of the Guinea savanna of Cameroon and related to cattle O. ochengi skin microfilaria abundance. During the 12 months study period, a total of 4 696 flies was individually dissected to examine the monthly transmission potential (MTP) of O. ochengi and O. volvulus. The estimated Simulium damnosum s.l. annual biting rates (ABR) on human baits were 47 529 flies at the bank of the Vina "du sud" river. The ABR at the lake, which was situated at about 2 km upland from the perennial river, was 8 579. The monthly parous rate was highly correlated with monthly biting rate. The annual transmission potentials (ATP) of O. ochengi were calculated to be 7 732 and 1 669 at the riverbank and the lake, respectively. Transmission occurred mainly in the dry season, peaking in the months of January to mid-March when dermal microfilaria density in the animals was also the highest. The O. ochengi microfilaria uptake by the fly vectors was host microfilaria density-dependent. The MTP of O. ochengi was positively correlated with dermal microfilaria density. The mean number of microfilariae per fly taken up during a blood meal was high during the dry season as was the mean number of infective larvae per fly but declined significantly with the onset of the early rains. A similar seasonality of transmission was also observed for O. volvulus that was concurrently transmitted by the same vector flies, but its ATP was comparatively much lower: 1 332 infective larvae per man per year at the riverbank and 107 around the lake. The population dynamics of cattle microfilariae therefore plays an important role in the regulation of O. ochengi transmission.transmission / Onchocerca ochengi / Onchocerca volvulus / microfilariae density / Simulium damnosum s.l. Vet. Res. 31 (2000) 611-621 611

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Section: Discussionmentioning

confidence: 73%

Section: Cattle Skin Microfilariaementioning

confidence: 99%

Onchocerca ochengitransmission dynamics and the correlation ofO. ochengimicrofilaria density in cattle with the transmission potential

2000

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“…The animals were treated with a proprietary anthelmintic (Panacur; Hoechst Roussel Vet) prior to entry into the experiment. O. ochengi microfilariae were obtained from the ventral skin of freshly slaughtered cattle from the Adamawa province of northern Cameroon (35). The parasites were extracted from skin and cryopreserved by established procedures (3,13) and then transported to the United Kingdom in liquid nitrogen.…”

Section: Methodsmentioning

confidence: 99%

Down-Regulated Lymphoproliferation Coincides with Parasite Maturation and with the Collapse of Both Gamma Interferon and Interleukin-4 Responses in a Bovine Model of Onchocerciasis

et al. 2001

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“…Nodules containing adult O. ochengi parasites were obtained from the skins of cattle slaughtered at Ngaoundéré abattoir in the Adamawa Region of Cameroon (Wahl et al 1994). Adult male and female worms were separated from excised nodules; the gonads were removed from the latter (selecting only nongravid individuals) and stored in PBS or RNAlater (Sigma) at À80°C, whereas the males were preserved whole.…”

Section: Parasite Materialsmentioning

confidence: 99%

Analysis of gene expression from theWolbachiagenome of a filarial nematode supports both metabolic and defensive roles within the symbiosis

et al. 2012

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The a-proteobacterium Wolbachia is probably the most prevalent, vertically transmitted symbiont on Earth. In contrast with its wide distribution in arthropods, Wolbachia is restricted to one family of animal-parasitic nematodes, the Onchocercidae. This includes filarial pathogens such as Onchocerca volvulus, the cause of human onchocerciasis, or river blindness. The symbiosis between filariae and Wolbachia is obligate, although the basis of this dependency is not fully understood. Previous studies suggested that Wolbachia may provision metabolites (e.g., haem, riboflavin, and nucleotides) and/or contribute to immune defense. Importantly, Wolbachia is restricted to somatic tissues in adult male worms, whereas females also harbor bacteria in the germline. We sought to characterize the nature of the symbiosis between Wolbachia and O. ochengi, a bovine parasite representing the closest relative of O. volvulus. First, we sequenced the complete genome of Wolbachia strain wOo, which revealed an inability to synthesize riboflavin de novo. Using RNA-seq, we also generated endobacterial transcriptomes from male soma and female germline. In the soma, transcripts for membrane transport and respiration were up-regulated, while the gonad exhibited enrichment for DNA replication and translation. The most abundant Wolbachia proteins, as determined by geLC-MS, included ligands for mammalian Toll-like receptors. Enzymes involved in nucleotide synthesis were dominant among metabolism-related proteins, whereas the haem biosynthetic pathway was poorly represented. We conclude that Wolbachia may have a mitochondrion-like function in the soma, generating ATP for its host. Moreover, the abundance of immunogenic proteins in wOo suggests a role in diverting the immune system toward an ineffective antibacterial response.

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Bovine onchocercosis in North Cameroon

Cited by 55 publications

References 15 publications

Onchocerca ochengitransmission dynamics and the correlation ofO. ochengimicrofilaria density in cattle with the transmission potential

Onchocerca ochengitransmission dynamics and the correlation ofO. ochengimicrofilaria density in cattle with the transmission potential

Down-Regulated Lymphoproliferation Coincides with Parasite Maturation and with the Collapse of Both Gamma Interferon and Interleukin-4 Responses in a Bovine Model of Onchocerciasis

Analysis of gene expression from theWolbachiagenome of a filarial nematode supports both metabolic and defensive roles within the symbiosis

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