Background In Mvoua, a village situated in a forested area of Cameroon, recent studies have reported high prevalence of Plasmodium falciparum infection among the population. In order to understand factors that can sustain such a high malaria transmission, we investigated the biology of Anopheles vectors and its susceptibility to insecticides, as well as long-lasting insecticidal net (LLIN) coverage, use and bio-efficacy. Methods A longitudinal entomological survey was conducted from July 2018 to April 2019. Adult mosquitoes were collected using the human landing catch (HLC) method and identified using morphological and molecular techniques. Anopheles gambiae (s.l.) larvae were sampled from several stagnant water pools throughout the village and reared to generate F1 adults. The presence of P. falciparum circumsporozoite antigen was detected in the heads and thoraces of mosquitoes collected as adults using an enzyme-linked immunosorbent assay. The insecticide susceptibility status of the local An. gambiae (s.l.) F1 population to the pyrethroid insecticides deltamethrin 0.5% and permethrin 0.75% was determined using World Health Organization-tube bioassays, while the frequency of the knockdown resistance (kdr) mutation was determined by PCR. Coverage, use and physical integrity of LLINs were assessed in households, then cone assays were used to test for their bio-efficacy on both the reference insecticide-susceptible Kisumu strain and on field F1 An. gambiae (s.l.) Results In total, 110 Anopheles mosquitoes were collected, of which 59.1% were identified as Anopheles funestus (s.l.), 38.18% as An. gambiae (s.l.) and 2.72% as An. ziemanii. Anopheles funestus was the most abundant species except in the long rainy season, when An. gambiae (s.l.) predominated (65.8%). In the dry seasons, vectors were principally endophagous (76% of those collected indoors) while they tended to be exophagous (66% of those collected outdoors) in rainy seasons. High Plasmodium infection was observed in An. gambiae (s.l.) and An. funestus, with a circumsporozoitic rate of 14.29 and 10.77%, respectively. Anopheles gambiae (s.l.) was highly resistant to pyrethroid insecticides (mortality rates: 32% for permethrin and 5% for deltamethrin) and harbored the kdr-L1014F mutation at a high frequency (89.74%). Of the 80 households surveyed, only 47.69% had achieved universal coverage with LLNs. Around 70% of the LLINs sampled were in poor physical condition, with a proportionate hole index > 300. Of the ten LLNs tested, eight were effective against the An. gambiae reference insecticide-susceptible Kisumu strain, showing mortality rate of > 80%, while none of these LLINs were efficient against local An. gamabie (s.l.) populations (mortality rates < 11.5%). Conclusion A combination of elevated P. falciparum infection in Anopheles vector populations, insufficient coverage and loss of effectiveness of LLINs due to physical degradation, as well as high resistance to pyrethroid insecticides is responsible for the persistence of high malaria transmission in forested rural area of Mvoua, Cameroon.
The structure and stability of parasite communities have been mainly explained by high diversity and strong interactions among parasite species. During 16 months, 558 Barbus martorelli gill infracommunities were studied in a tropical zone to determine whether parasite infrapopulations interact. Three levels were retained: the infracommunity level, the gill filament level, and the filament fraction level. Single species infections in Barbus martorelli were very rare and only concerned the core species: Dactylogyrus bopeleti, D. insolitus, D. simplex and Myxobolus barbi. Mixed infections appeared as a general rule in this fish species. Interspecific interactions at all three levels were statistically non significant. Our results suggest that Barbus martorelli gill parasites are non interactive (isolationist).
L’étude de la parasitofaune branchiale de 558 Barbus martorelli a été menée dans un cours d’eau douce aux alentours de Yaoundé (Cameroun) en milieu tropical, afin d’obtenir des informations sur la répartition des agents pathogènes dans une population d’hôtes sauvages ; ces données sont indispensables dans la recherche de moyens pour éviter les pertes énormes souvent observées en pisciculture intensive. Cette analyse a révélé la présence de deux espèces de myxosporidies (Myxobolus barbi et M. njinei) et de huit espèces de monogènes (Dactylogyrus bopeleti, D. insolitus, D. simplex, D. maillardi, Dogielius martorellii, Dogielius sp., une espèce de Gyrodactylidae et une larve de Polystomatidae). Quatre poissons n’ont pas présenté de parasites, 24 ont présenté une infection monospécifique et 530 une infection plurispécifique. Chaque individu infesté a hébergé en moyenne quatre espèces de parasites. Alors que la prévalence et l’intensité moyenne parasitaire diminuaient avec la taille de l’hôte pour les protozoaires, le phénomène inverse a été observé pour les helminthes. L’effet sexe a été noté dans l’infestation de B. martorelli par la myxosporidie M. njinei et par la plupart des espèces de monogènes. Les femelles ont ainsi été plus infestées que les mâles en raison de leur biologie en période de frai. Enfin, la richesse des espèces parasitaires a semblé affecter négativement le poids des hôtes.
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.
Primates are known to harbour different gastrointestinal parasite species that affect their survival and reproductive activity. Entamoeba histolytica infects humans predominantly as well as non-human (NH) primates causing amoebiasis. Amoebic dysentery is common amongst non-human primates in captive sites. The purpose of the study was to evaluate the risk factors associated with the prevalence of amoebic dysentery in captive NH primates of the Mefou Primate Sanctuary (MPS) in Cameroon. The faecal samples of 277 NH primates were analysed by qualitative (direct smear and evergreen kit sedimentation technique) coprology from January to July 2019. Factors such as habitat type, keeper’s age and level of education were assessed to evaluate their effect on the prevalence of amoebic dysentery. The prevalence of Entamoeba histolytica was 46.2% (P=0,079 and χ2=18.13). E histolytica was the most predominant parasite species detected and it was present in all instances of mixed parasite infections. Amongst the NH primates positive for E. histolytica, 28 suffered from amoebic dysentery giving a prevalence of 21.9% and one of the infected primates (Cercopithecus pogonias) actually died from amoebic dysentery. The prevalence of mixed infections was significantly lower amongst NH primates living in outdoor enclosures compared to those living in other habitat types (P=0.015, χ2=10.46). The rate of re-infection was significantly higher amongst NH primates under the care of keepers with the lowest (primary school) level of education (P=0.001, χ2=13.09) on one hand and of older keepers (≥50s) (P = 0.008, χ2=13.708) on the other hand. This study shows that amoebic dysentery is a cause for a major concern in the MPS. The housing conditions of the NH primates at the sanctuary, the keeper’s age and level of education were important factors that influenced the prevalence of amoebic dysentery. Adequate measures should be put in place to address the situation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.