Ecology of three monogenean ectoparasites of Barbus camptacanthus (Teleostei: Cyprinid) from the Koukoum River, Cameroon

Objective: In September 2014, 56 specimens of Barbus camptacanthus were captured in the Koukoum River at Makak (Cameroon) in order to study some ecological aspects of their monogenean gill parasites.Methodology and Results: After host sampling and parasites mounting, determination of various monogenean species was carried out in the laboratory by classical methods. Gill helminthofauna of this fish consisted of Dactylogyrus amieti, D. valeti and Dogielius njinei. The parasite load of core species increased progressively with the size of the fish. The impact of host sex was observed for D. amieti and Dogielius njinei parasite load. The infestation rate and the parasite load did not statistically vary with the side of the host. The colonization profile of different gradients varied depending on the parasite species.Conclusion and Application: The study of the distribution of these organisms has identified the most vulnerable hosts. Such information allows envisaging some protocols for monitoring parasitic infection in intensive fish farming. In hatcheries, much care should be given to fry and young fish since they have not yet developed robust immunological processes that enable them to effectively fight against polyparasitism.Keywords: Barbus camptacanthus, gills, monogeneans, distribution, Koukoum Rive

Entomological longitudinal surveys in two contrasted eco-climatic settings in Cameroon reveal a high malaria transmission from Anopheles funestus associated with GSTe2 metabolic resistance

Background: The impact of metabolic resistance to insecticides on malaria transmission remains poorly characterised notably through application of entomological parameters. The lack of resistance markers has been one of the limiting factors preventing a robust assessment of such impact. To this end, the present study sought to investigate how the L119F-Gste2 metabolic gene influences entomological parameters underpinning mosquitos’ propensity to transmit Plasmodium spp. Methods: Longitudinal studies were carried out in Mibellon and Elende, two different eco-climatic settings in Cameroon and mosquitoes were collected using Human Landing Catch (HLC), Centre for Disease Control Light Trap (CDC-LT) and Pyrethrum Spray Catch (PSC) technics. Plasmodium sporozoite parasites were detected by TaqMan and Nested PCR, and blood meal origin by ELISA. The allele-specific PCR (AS-PCR) method was used to genotype the L119F-GSTe2 marker and association with malaria transmission was established by comparing key transmission parameters such as the Entomological Inoculation Rate (EIR) between individuals with different L119F-GSTe2 genotypes. Results: An. funestus s.l was the predominant malaria vector collected during the entomological survey in both sites (86.6% and 96.4% in Elende and Mibellon, respectively) followed by An. gambiae s.l (7.5% and 2.4%, respectively). Sporozoite infection rates were very high in both collection sites (8.7% and 11% in Elende and Mibellon, respectively). An. funestus s.s exhibited a very high entomological inoculation rate (EIR) (66 ib/h/month and 792 ib/h/year) and was responsible for 98.6% of all malaria transmission events occurring in both sites. The Human Blood Index was also high in both locations (HBI = 94%). An. funestus s.s. mosquitoes with both 119 F/F (RR) and L119F (RS) genotypes had a significantly higher transmission intensity than their susceptible L/L119 (SS) counterparts (IRR = 2.2, 95%CI (1.1–5.2), p = 0.03; IRR = 2.5, 95% CI (1.2–5.8), p = 0.01 respectively). Conclusion: This study highlights the major role that An. funestus s.s plays in malaria transmission in Cameroon with an aggravation from GSTe2-based metabolic resistance

Bendiocarb and Malathion Resistance in Two Major Malaria Vector Populations in Cameroon Is Associated with High Frequency of the G119S Mutation (Ace-1) and Overexpression of Detoxification Genes

The spread of pyrethroid resistance in malaria vectors is a major threat affecting the performance of current control measures. However, there is still not enough information on the resistance profile of mosquitoes to carbamates and organophosphates which could be used as alternatives. The present study assessed the resistance profile of Anopheles gambiae s.l. to bendiocarb and malathion, at the phenotypic and molecular levels, in different eco-epidemiological settings in Cameroon. Anopheles gambiae s.l. mosquitoes were collected from four eco-epidemiological settings across the country and their susceptibility level to bendiocarb and malathion was determined using WHO tubes bioassays. The ace-1 target site G119S mutation was screened by PCR. Reverse Transcription quantitative PCR 3-plex TaqMan assays were used to quantify the level of expression of eight genes associated with metabolic resistance. Resistance to malathion and/or bendiocarb was recorded in all study sites except in mosquitoes collected in Kaélé and Njombé. The Ace-1 (G119S) mutation was detected in high frequencies (>40%) in Kékem and Santchou. Both An. gambiae and An. coluzzii were detected carrying this mutation. The cytochrome P450s gene Cyp6p3 associated with carbamate resistance and the glutathione S-transferase gene Gste2 associated with organophosphate resistance were found to be overexpressed. Genes associated with pyrethroid (Cyp6m2, Cyp9k1, Cyp6p3) and organochlorine (Gste2, Cyp6z1, Cyp6m2) and cuticle resistance (Cyp4g16) were also overexpressed. The rapid spread of resistance to organophosphates and carbamates could seriously compromise future control strategies based on IRS. It is therefore becoming important to assess the magnitude of bendiocarb and malathion resistance countrywide

Description of two new ancyrocephalid (Quadriacanthus and Bagrobdella) monogenea from the gills of Auchenoglanid catfishes (Pisces, Siluriformes, Claroteidae) in Cameroon

International audienceParasitological survey of the gill filaments of Anaspidoglanis macrostoma and Parauchenoglanis monkei (Claroteidae) from the Memou'ou, a River Nyong tributary in South Cameroon, revealed the presence on these hosts of Quadriacanthus anaspidoglanii n. sp. and Bagrobdella parauchenoglanii n. sp., respectively. Quadriacanthus anaspidoglanii n. sp. is differentiated from other congeneric species by the size of haptoral parts and male copulatory complex. Bagrobdella parauchenoglanii n. sp. differs from other congeneric species by the shape and size of the male copulatory complex (not coiled penis, presence of an accessory piece). The presence of a Quadriacanthus species on an Auchenoglanidinae host (usually parasitized by monogeneans belonging to Bagrobdella) is recorded for the first time and suggests that it could be the results of a lateral transfer between hosts from these two different Siluriforme families (Clariidae and Claroteidae), living in sympatry