Integrated xenosurveillance of Loa loa, Wuchereria bancrofti, Mansonella perstans and Plasmodium falciparum using mosquito carcasses and faeces: A pilot study in Cameroon.

Background Community presence of loiasis must be determined before mass drug administration programmes for lymphatic filariasis and onchocerciasis can be implemented. However, taking human blood samples for loiasis surveillance is invasive and operationally challenging. A xenosurveillance approach based on the molecular screening of mosquitoes and their excreta/feces (E/F) for Loa loa DNA may provide a non-invasive method for detecting the community presence of loiasis. Methods We collected 770 wild mosquitoes during a pilot study in a known loiasis transmission area in Mbalmayo, Cameroon. Of these, 376 were preserved immediately while 394 were kept in pools to collect 36-hour E/F samples before processing. Carcasses and E/F were screened for L. loa DNA. To demonstrate this method’s potential for integrated disease surveillance, the samples were further tested for Wuchereria bancrofti, Mansonella perstans, and Plasmodium falciparum. Results Despite limited sample numbers, L. loa DNA was detected in eight immediately-stored mosquitoes (2.13%; 95% CI 1.08 to 4.14), one carcass stored after providing E/F (0.25%; 95% CI 0.04 to 1.42), and three E/F samples (estimated prevalence 0.77%; 95% CI 0.15 to 2.23%). M. perstans and P. falciparum DNA were also detected in carcasses and E/F samples, while W. bancrofti DNA was detected in E/F. None of the carcasses positive for filarial worm DNA came from pools that provided a positive E/F sample, supporting the theory that, in incompetent vectors, ingested parasites undergo a rapid, complete expulsion in E/F. Conclusions Mosquito xenosurveillance may provide a useful tool for the surveillance of loiasis alongside other parasitic diseases

Plasmodium malariae contributes to high levels of malaria transmission in a forest–savannah transition area in Cameroon

Background: Malaria control efforts are highly skewed towards Plasmodium falciparum while overlooking other Plasmodium species such as P. malariae. A better understanding of the role of Plasmodium species other than P. falciparum is needed to strengthen malaria elimination initiatives. The aim of the present study was to elucidate the contribution of P. malariae to malaria transmission in Cameroon. Methods: The study was conducted in the Ngatti Health District, a forest–savannah transition area in the Adamawa Region, Cameroon. A total of 497 individuals aged from 1 to 85 years were diagnosed with malaria in November 2020 using a rapid diagnostic test (RDT) and microscopy. Adult mosquitoes were collected between September 2019 and March 2020 by indoor aspiration and identified morphologically and molecularly. The infection status of Plasmodium spp. was also determined by quantitative PCR, and dried blood spots were collected from 156 participants with the aim to detect different Plasmodium species by nested PCR. Results: The overall Plasmodium prevalence was 50.3%, 51.8% and 64.7%, as detected by microscopy, the RDT and PCR, respectively. Based on the PCR results, P. falciparum was the most prevalent species (43%); followed by co-infections P. falciparum/P. malariae (17%), P. falciparum/P. ovale (1.3%), P. falciparum/P. ovale/P. malariae (1.3%); and then by P. malariae mono-infection (2.5%). The same trend was observed using microscopy, with 35% of participants infected with P. falciparum, 11% co-infected with P. falciparum/P. malariae and 4% infected with P. malariae. The prevalence and parasite density of malaria infection varied significantly with age group (P < 0.05), with the highest prevalence rate observed in children aged 6–10 years (P = 0.0001) while the density of Plasmodium infection increased significantly in children aged < 5 years compared to the other age groups (P = 10−3). Among the 757 Anopheles mosquitoes collected, 737 (97.35%) were An. funestus sensu stricto, 15 (1.9%) were An. gambiae and 5 (0.6%) were An. hancocki. The Plasmodium species recorded at the head/thorax level were P. falciparum and P. malariae, with a sporozoite infection rate of 8.4%; the highest sporozoite infection rate was recorded at Mibellon village (13.6%). Conclusion: The results of this study reveal the significant contribution of P. malariae, in addition to P. falciparum, to the high malaria transmission rate in this region. These findings highlight the need to deploy initiatives to also tackle this Plasmodium species to eliminate malaria in the region

Antibacterial and antioxidant activities of the extract and some flavonoids from aerial parts of Echinops Gracilis O. Hoffm. (Asteraceae)

Mortality due to microbial diseases continues to be a major problem in many developing countries. The present study aims to evaluate the antibacterial and antioxidant activities of the ethyl acetate extract and some isolated compounds from aerial parts of Echinops gracilis. The phytochemical study resulted in the isolation of a new flavonoid derivative named apigenin-7-O-(4″-feruloyl)-β-D-glucoside (1), together with 2 known compounds: apigenin-7-O-(4″-trans-p-hydroxycinnamoyl)-β-D-glucoside (2), and apigenin-7-O-glucoside (3). Their chemical structures were determined using a combination of NMR and IR spectroscopic and MS techniques, as well as by comparison with literature data. The extract and isolates were evaluated for their antibacterial and antioxydant properties. The EtOAc extract and compounds 1 and 2 showed the ability to scavenge 2,2′-zino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS) with scavenging concentration (SC50) values of 13.6 ± 0.8 µg/mL, 108.2 ± 4.3 µg/mL, and 28.5 ± 2.2 µg/mL, respectively. In addition, compound 1 displayed significant activity against Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumonia, with minimum inhibition concentration (MIC) values of 31.2, 15.6, and 31.2 µg/mL respectively.https://journals.sagepub.com/home/npxhj2022Chemistr

Antipromastigote and cytotoxic activities of some chemical constituents of Hypericum lanceolatum Lam.

Phytochemical investigation of the ethanol extract of the stem bark of Hypericum lanceolatum Lam. (Guttifereae) afforded eight known compounds including 2,2ʹ,5,6ʹ-tetrahydroxybenzophenone (1), 5-hydroxy-3-methoxyxanthone (2), 3-hydroxy-5-methoxyxanthone (3), betulinic acid (4), hydroquinone (5) 6,7-dihydroxy-1,3-dimethoxyxanthone (6), calophyllumin A (7), and 1,3,5,6-tetrahydroxy-4-prenylxanthone (8). Compound 1 was submitted to acetylation reaction to give 5-acetoxy-2,2ʹ,6ʹ-trihydroxybenzophenone (9), a new hemisynthetic derivative. Compounds 5 and 8 were isolated for the first time from this plant. The structures were established by extensive analysis of their mass spectrometry and nuclear magnetic resonance (NMR) spectroscopic data and comparison with those from the literature. The isolated compounds (1, 2, 4, 5, and 8) and the derivative of benzophenone (9) were tested for their antipromastigote and cytotoxic activities against visceral leishmaniasis parasite Leishmania donovani and macrophage RAW 264.7 cell line, respectively. Compound 9 was the most active with an IC50 value of 6.1 μg/ml, while compounds 1, 2, 4, and 8 were moderately active with IC50 values ranging from 11.4 to 34.8 μg/ml against L. donovani and were not cytotoxic except compound 5 that was very toxic and not active. The findings of the present study suggested that compounds 1, 2, 4, and 8 could be considered as a potential source of therapeutic medicine for the treatment of leishmaniasis

Limited association between <i>Wolbachia</i> and <i>Plasmodium falciparum</i> infections in natural populations of the major malaria mosquito <i>Anopheles moucheti</i>

International audienceSince the discovery of natural malaria vector populations infected by the endosymbi-ont bacterium Wolbachia, a renewed interest has arisen for using this bacterium as analternative for malaria control. Among naturally infected mosquitoes, Anopheles mou-cheti, a major malaria mosquito in Central Africa, exhibits one of the highest preva-lences of Wolbachia infection. To better understand whether this maternally inheritedbacterium could be used for malaria control, we investigated Wolbachia influence inAn. moucheti populations naturally infected by the malaria parasite Plasmodium fal-ciparum. To this end, we collected mosquitoes in a village from Cameroon, CentralAfrica, where this mosquito is the main malaria vector. We found that the prevalenceof Wolbachia bacterium was almost fixed in the studied mosquito population, andwas higher than previously recorded. We also quantified Wolbachia in whole mosqui-toes and dissected abdomens, confirming that the bacterium is also elsewhere than inthe abdomen, but at lower density. Finally, we analyzed the association of Wolbachiapresence and density on P. falciparum infection. Wolbachia density was slightly higherin mosquitoes infected with the malaria parasite than in uninfected mosquitoes.However, we observed no correlation between the P. falciparum and Wolbachia densi-ties. In conclusion, our study indicates that naturally occurring Wolbachia infection isnot associated to P. falciparum development within An. moucheti mosquitoes

A chromosomal reference genome sequence for the malaria mosquito, Anopheles moucheti, Evans, 1925.

We present a genome assembly from an individual male Anopheles moucheti (the malaria mosquito; Arthropoda; Insecta; Diptera; Culicidae), from a wild population in Cameroon. The genome sequence is 271 megabases in span. The majority of the assembly is scaffolded into three chromosomal pseudomolecules with the X sex chromosome assembled. The complete mitochondrial genome was also assembled and is 15.5 kilobases in length

A chromosomal reference genome sequence for the malaria mosquito, Anopheles moucheti, Evans, 1925

International audienceWe present a genome assembly from an individual male Anopheles moucheti (the malaria mosquito; Arthropoda; Insecta; Diptera; Culicidae), from a wild population in Cameroon. The genome sequence is 271 megabases in span. The majority of the assembly is scaffolded into three chromosomal pseudomolecules with the X sex chromosome assembled. The complete mitochondrial genome was also assembled and is 15.5 kilobases in length