Publications by authors named "Jean Claude Toto"
Article Synopsis
- Cameroon has experienced significant urban population growth, with over 67% of urban residents living in slums, and these areas are expanding at a rate of 5.5% annually, prompting concerns about disease transmission and mosquito populations.
- A review of 85 studies from 2002-2021 identified 10 diseases transmitted by mosquitoes, with rising prevalence rates in urban areas for diseases like dengue, while rural areas saw the emergence of previously absent diseases such as Lymphatic filariasis and Rift valley fever.
- Malaria prevalence remained stable in urban settings but decreased in rural areas during the same period, highlighting different disease dynamics in urban versus rural environments.
Article Synopsis
- Malaria is a significant health issue in Cameroon, prompting a study of malaria vector surveillance conducted from October 2018 to September 2020 across five sites in the country.
- Various methods were employed, including human landing catches and light traps, to measure aspects like mosquito density and infection rates, ultimately collecting over 139,000 Anopheles mosquitoes from multiple species.
- Anopheles gambiae was identified as the primary malaria vector, with a high indoor biting rate observed and significant variations in infection rates and human biting rates across different locations.
Article Synopsis
- Understanding the mechanisms behind insecticide resistance in malaria vectors is crucial for effective vector control, specifically focusing on metabolic resistance and genetic variations in North Cameroon.
- The study compared mosquito populations from different regions before and after the distribution of long-lasting insecticidal nets (LLINs), finding increased metabolic resistance in one area, while two others showed decreased effectiveness.
- Genetic analysis showed mixed trends in resistance alleles, indicating evolving resistance patterns, and emphasized the need for alternative vector control methods alongside LLINs in North Cameroon.
Correction to: Epidemiological and entomological studies of malaria transmission in Tibati, Adamawa region of Cameroon 6 years following the introduction of long-lasting insecticide nets.
Parasit Vectors
October 2021
Previous studies have indicated widespread insecticide resistance in malaria vector populations from Cameroon. However, the intensity of this resistance and underlying mechanisms are poorly known. Therefore, we conducted three cross-sectional resistance surveys between April 2018 and October 2019, using the revised World Health Organization protocol, which includes resistance incidences and intensity assessments.
View Article and Find Full Text PDFEpidemiological and entomological studies of malaria transmission in Tibati, Adamawa region of Cameroon 6 years following the introduction of long-lasting insecticide nets.
Parasit Vectors
May 2021
Article Synopsis
- - Malaria is a significant public health issue in Cameroon, necessitating an understanding of local conditions for effective control measures; this research presents findings from Tibati, an area affected by seasonal malaria transmission, six years after long-lasting insecticidal bed nets were introduced.
- - Cross-sectional studies conducted in 2015 and 2017 involved blood samples from both symptomatic and asymptomatic individuals, along with adult mosquito collections, to assess the prevalence of Plasmodium species and identify infected mosquitoes through molecular methods.
- - The study revealed a 55% overall malaria prevalence, primarily caused by Plasmodium falciparum, with higher rates found in asymptomatic carriers; mosquito collections identified several species with a small percentage infected, highlighting the
Background: The rapid and unplanned urbanization of African cities is considered to increase the risk of urban malaria transmission. The present study objective was to assess factors influencing the spatio-temporal distribution of Anopheles gambiae s.l.
View Article and Find Full Text PDFArticle Synopsis
- Effective malaria control in North Cameroon was studied after the distribution of long-lasting insecticidal nets (LLINs) in 2010, focusing on Anopheline mosquito behavior and Plasmodium infections from 2011 to 2014.
- Researchers collected 9,376 Anopheline mosquitoes, identifying 14 species, with Anopheles gambiae being the most common, and found that blood meals were mainly from humans and livestock, with indoor Pf-CSP infection rates higher than outdoors.
- The study concluded that even with LLINs, malaria prevalence in children under five was still significant (30%), indicating a need for additional malaria prevention measures.
Dam constructions are considered a great concern for public health. The current study aimed to investigate malaria transmission in the Nyabessan village around the Memve'ele dam in South Cameroon. Adult mosquitoes were captured by human landing catches in Nyabessan before and during dam construction in 2000-2006 and 2014-2016 respectively, as well as in the Olama village, which was selected as a control.
View Article and Find Full Text PDFThe effectiveness of insecticide-based malaria vector control interventions in Africa is threatened by the spread and intensification of pyrethroid resistance in targeted mosquito populations. The present study aimed at investigating the temporal and spatial dynamics of deltamethrin resistance in An. gambiae s.
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- * A comprehensive study conducted from March 2017 to March 2018 involved trapping and analyzing over 218,000 mosquitoes to understand their species composition, infection rates, and behavior, revealing that outdoor biting rates were considerably higher than indoor.
- * The findings indicated a high malaria transmission risk, especially outdoors, with certain mosquito populations showing resistance to key insecticides and a prevalence of genetic traits that could affect control efforts, emphasizing the need for enhanced malaria control strategies in urban settings.
Background: Following the recent discovery of the role of Anopheles rufipes Gough, 1910 in human malaria transmission in the northern savannah of Cameroon, we report here additional information on its feeding and resting habits and its susceptibility to the pyrethroid insecticide deltamethrin.
Methods: From 2011 to 2015, mosquito samples were collected in 38 locations across Garoua, Mayo Oulo and Pitoa health districts in North Cameroon. Adult anophelines collected using outdoor clay pots, window exit traps and indoor spray catches were checked for feeding status, blood meal origin and Plasmodium circumsporozoite protein.
Article Synopsis
- Anopheles funestus is a key malaria vector in sub-Saharan Africa, but research on its interactions with the malaria parasite P. falciparum has been limited due to challenges in studying this species.
- This study successfully infected wild-caught An. funestus females with P. falciparum and compared their infection rates with a known susceptible species, An. coluzzii, revealing comparable susceptibility levels.
- The findings show a 38.52% prevalence of infection in An. funestus and a similar 39.92% in An. coluzzii, suggesting both mosquito species can effectively carry the malaria parasite.
From 2003 to 2007, entomological surveys were conducted in Lobito town (Benguela Province, Angola) to determine which Anopheles species were present and to identify the vectors responsible for malaria transmission in areas where workers of the Sonamet Company live. Two types of surveys were conducted: (1) time and space surveys in the low and upper parts of Lobito during the rainy and dry periods; (2) a two-year longitudinal study in Sonamet workers' houses provided with long-lasting insecticide-treated nets (LLIN), "PermaNet," along with the neighboring community. Both species, An.
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- Anopheles mosquitoes in Cameroon are showing increasing resistance to DDT and pyrethroids, which poses challenges for malaria vector control efforts.
- The study involved collecting and testing mosquito samples from various regions, revealing differing susceptibility levels, particularly with An. arabiensis being fully susceptible to some insecticides.
- The findings highlight the presence of resistant populations, with detoxifying enzymes affecting survival rates, and indicate that genetic resistance mechanisms, like kdr mutations, play a significant role in the resistance observed.
Article Synopsis
- * Significant reductions in mosquito populations, malaria infections, and immune responses were recorded, particularly where long-lasting insecticide-treated nets (LLIN) and insecticide-treated plastic sheeting (ITPS-ZF) were used together.
- * Findings suggest that using a combination of vector control methods is more effective in reducing malaria risks than using a single method, indicating a need for broader application of this strategy.
Background: The spread of insecticide resistance in the malaria mosquito, Anopheles gambiae is a serious threat for current vector control strategies which rely on the use of insecticides. Two mutations at position 1014 of the S6 transmembrane segment of domain II in the voltage gated sodium channel, known as kdr (knockdown resistance) mutations leading to a change of a Leucine to a Phenylalanine (L1014F) or to a Serine (L1014S) confer resistance to DDT and pyrethroid insecticides in the insect. This paper presents the current distribution of the kdr alleles in wild Anopheles gambiae populations in Cameroon.
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- * A study was conducted to validate the effectiveness of this biomarker by assessing immune responses in individuals before and after using Insecticide Treated Nets (ITNs) in a malaria-endemic region.
- * Results showed a significant drop in specific antibodies (IgG) against the gSG6-P1 peptide immediately after ITN use, indicating its potential as a reliable indicator for both short-term and longer-term evaluations of ITN effectiveness in reducing human-vector contact.
Article Synopsis
- The WHO is seeking better ways to assess the effectiveness of malaria vector-control strategies, specifically through new indicators.
- This research focuses on measuring human antibody responses to Anopheles mosquito saliva as a potential new indicator for evaluating insecticide-treated nets (ITNs) effectiveness.
- Findings showed that after introducing ITNs in Angola, there was a notable decrease in antibodies linked to mosquito exposure and a significant reduction in malaria infection rates.
Background: Highland areas of Africa are mostly malaria hypoendemic, due to climate which is not appropriate for anophelines development and their reproductive fitness. In view of designing a malaria control strategy in Western Cameroon highlands, baseline data on anopheline species bionomics were collected.
Methods: Longitudinal entomological surveys were conducted in three localities at different altitudinal levels.
Article Synopsis
- Pyrethroid insecticides are extensively used in Cameroon for pest control, particularly against malaria vectors like Anopheles gambiae, and monitoring resistance is crucial for effective vector control.
- A study conducted from 2001 to 2007 in South Cameroon analyzed mosquito populations for resistance to DDT and pyrethroids, with interviews assessing local insecticide use.
- Results showed significant variations in resistance levels across locations, with the emergence of kdr mutations correlating to increased insecticide resistance in most areas, though one locality (Mangoum) showed a decrease in resistance despite a rise in kdr allele frequency.
Article Synopsis
- The study examined genetic variations in the voltage-gated sodium channel gene within Anopheles gambiae mosquitoes from Cameroon to understand the emergence of knockdown resistance (kdr) alleles.
- Sampling took place from three regions between December 2005 and June 2006, revealing the presence of two kdr alleles (1014S and 1014F) in the S-form and one (1014F) in the M-form of mosquitoes.
- The research identified four distinct mutation events leading to the kdr alleles and indicated potential hybridization between the two forms, underscoring the rapid spread of these alleles and the need for improved management strategies against insecticide resistance in mosquito populations in Africa.
Some populations of Anopheles gambiae s.l. from Cameroon were reported to develop resistance to DDT or pyrethroids but were free of the kdr mutation "Leucine-Phenylalanine" (Leu-Phe).
View Article and Find Full Text PDFA trial of permethrin-treated nets (PTNs) versus untreated nets (UTNs) was conducted in Pitoa (north Cameroon), where the main malaria vectors, Anopheles gambiae s.l. and Anopheles arabiensis, show metabolic-based permethrin resistance.
View Article and Find Full Text PDFPresence in Cameroon of the recently introduced Aedes (Stegomyia) albopictus (Skuse) in association with the indigenous Aedes aegypti (L.) raises public heath concerns because it might alter the risk of arbovirus transmission. The breeding site and distribution of the two Stegomyia species are updated and reported following entomological surveys carried out in 22 localities throughout Cameroon, with a total of 1,353 containers with water visited.
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