Predictors of organoleptic quality of boiled and dried pulp of safou (dacryodes edulis) and the shelf life of its fresh fruits

Introduction. The high intra-specific variation in safou traits and the perishable nature of the fruit hampers commercialization. Knowledge of the parameters that determine the acceptability of safou products and the shelf life of fresh fruits is critical for marketing and useful as a first step toward cultivar development. Materials and methods. Safou fruits of different pulp colors, skin colors and stages of ripening were collected from clones. Physicochemical and organoleptic analyses were performed on fresh and processed safou pulp, respectively, to elucidate parameters that could be used to determine the acceptability of boiled and dried safou pulp, and the shelf life of fresh fruits. Results and discussions. Our study demonstrated that the pH and color of raw pulp could be used to determine the acceptability of boiled and dried safou. Consumers preferred products which were not acidic (sour), with a nice aroma. There was a negative correlation between the pH of raw pulp and the acceptability of boiled and dried safou pulp. Likewise, there was a positive correlation between the color of raw pulp and the acceptability of boiled and dried safou pulp. These parameters were used to predict the taste of finished products. Polygalacturonase activity was higher in fully ripe and unripe fruits than in semi-ripe fruits. Polygalacturonase activity had a strong positive correlation with percentage loss of fully ripe fruit during storage and, as such, can also be used to predict the postharvest loss of safou. Conclusion. The pH and color of raw (uncooked) pulp of safou can be used to determine the taste and acceptability of boiled and dried pulp. Likewise, the activity of polygalacturonase in raw pulp can be used to predict its postharvest shelf life. (Résumé d'auteur

Inauguration of the Cameroonian Society of Human Genetics

The conjunction of “hard genetics” research centers, with well established biomedical and bioethics research groups, and the exceptional possibility to hold the 6th annual meeting of the African Society of Human Genetics (AfSHG, 13th–15th March 2009) was an excellent opportunity to get together in synergy the entire Cameroonian “DNA/RNA scientists” . This laid to the foundation of the Cameroonian Society of Human Genetics (CSHG) that was privilege to hold its inaugural meeting in conjunction to the 6th annual meeting of the AfSHG. The theme was "Human Origin, Genetic Diversity and Health”. The AfSHG and CSHG invited leading African and international scientists in genomics and population genetics to review recent data and provide an understanding of the state-of-knowledge of Human Origin and Genetic Diversity. Overall one opening ceremony eight session, five keynote and guest speakers, 18 invited oral communications, 13 free oral communications, 43 posters and two social events could summarize the meeting. This year’s conference was graced by the presence of one Nobel Prize winner Dr Richard Roberts (Physiology and Medicine 1993). The meeting registered up to ten contributions of Cameroonian scientists from the Diaspora (currently in USA, Belgium, Gambia, Sudan and Zimbabwe). Such Diaspora participation is an opportunity to generate collaborations with home country scientists and ultimately turn the “brain drain” to “brain circulation” that could reduce the impact of the migration of health professional from Africa. Interestingly, the personal implication of the Cameroonian Ministry of Public Heath who opened the meeting in the presence of the Secretary General of the Ministry of Higher Education and a representative of the Ministry of Scientific Research and Innovation was a wonderful opportunity for advocacy of genetic issues at the decision-makers level. Beyond our expectation, a major promise of the Cameroonian government was the creation of the National Human Genome Institute. If this goal comes true, this will be a critical step to bring more genetics for the purpose of Public Health to the Cameroonian people. The sub-Saharan African Region needs significant capacity building in the broad area of basic research in general and Genetics (especially Human Genetics) in particular. In that respect, the existence and current activities of the AfSHG and its impact at the National levels in Africa, is a major development for the continent and an initiative that needs further encouragement from the international community

Malaria vectors and transmission dynamics in coastal south-western Cameroon

BACKGROUND: Malaria is a major public health problem in Cameroon. Unlike in the southern forested areas where the epidemiology of malaria has been better studied prior to the implementation of control activities, little is known about the distribution and role of anophelines in malaria transmission in the coastal areas. METHODS: A 12-month longitudinal entomological survey was conducted in Tiko, Limbe and Idenau from August 2001 to July 2002. Mosquitoes captured indoors on human volunteers were identified morphologically. Species of the Anopheles gambiae complex were identified using the polymerase chain reaction (PCR). Mosquito infectivity was detected by the enzyme-linked immunosorbent assay and PCR. Malariometric indices (plasmodic index, gametocytic index, parasite species prevalence) were determined in three age groups (<5 yrs, 5–15 yrs, >15 yrs) and followed-up once every three months. RESULTS: In all, 2,773 malaria vectors comprising Anopheles gambiae (78.2%), Anopheles funestus (17.4%) and Anopheles nili (7.4%) were captured. Anopheles melas was not anthropophagic. Anopheles gambiae had the highest infection rates. There were 287, 160 and 149 infective bites/person/year in Tiko, Limbe and Idenau, respectively. Anopheles gambiae accounted for 72.7%, An. funestus for 23% and An. nili for 4.3% of the transmission. The prevalence of malaria parasitaemia was 41.5% in children <5 years of age, 31.5% in those 5–15 years and 10.5% in those >15 years, and Plasmodium falciparum was the predominant parasite species. CONCLUSION: Malaria transmission is perennial, rainfall dependent and An. melas does not contribute to transmission. These findings are important in the planning and implementation of malaria control activities in coastal Cameroon and West Africa

Resting Behaviour of Deltamethrin-Resistant Malaria Vectors, Anopheles arabiensis and Anopheles coluzzii, from North Cameroon: Upshots from a Two-Level Ordinary Logit Model

The current study was conducted in Garoua, Pitoa, and Mayo-Oulo health districts of north Cameroon, in order to investigate the resting behaviour of deltamethrin-resistant Anopheles (An.) gambiae s.l. populations and build a model of their response to the use of Permanet 2.0 long-lasting insecticidal nets (LLINs). Adult mosquitoes were collected in October and November 2011, using spray catches and window exit traps in 29 clusters with LLINs in use. Sampled An. gambiae s.l. were identified down to species and analysed for blood-meal origin, physiological and circumsporozoite protein status. Deltamethrin resistance was assessed using World Health Organization’s (WHO’s) standard protocol. A two-level ordinary logit model was used to relate the resting behaviour and deltamethrin resistance. Identified species of the An. gambiae complex included An. arabiensis (90.6%), An. coluzzii (7.1%) and An. gambiae s.s. (2.3%). They displayed 1.1–4.8% infection rates, 80% indoor-resting density and 56–80% human blood index. Eleven An. gambiae s.l. populations over the 15 tested were resistant to deltamethrin (51–89.5% mortality rates). Model results showed a significant dependence of indoor vector density on increasing deltamethrin resistance (p-value of <0.01). These behavioural and resistance patterns may lead to increasing malaria transmission in study health districts

Review of malaria situation in Cameroon: technical viewpoint on challenges and prospects for disease elimination

Abstract Malaria still has a devastating impact on public health and welfare in Cameroon. Despite the increasing number of studies conducted on disease prevalence, transmission patterns or treatment, there are to date, not enough studies summarising findings from previous works in order to identify gaps in knowledge and areas of interest where further evidence is needed to drive malaria elimination efforts. The present study seeks to address these gaps by providing a review of studies conducted so far on malaria in Cameroon since the 1940s to date. Over 250 scientific publications were consulted for this purpose. Although there has been increased scale-up of vector control interventions which significantly reduced the morbidity and mortality to malaria across the country from a prevalence of 41% of the population reporting at least one malaria case episode in 2000 to a prevalence of 24% in 2017, the situation is not yet under control. There is a high variability in disease endemicity between epidemiological settings with prevalence of Plasmodium parasitaemia varying from 7 to 85% in children aged 6 months to 15 years after long-lasting insecticidal nets (LLINs) scale-up. Four species of Plasmodium have been recorded across the country including Plasmodium falciparum, P. malariae, P. ovale and P. vivax. Several primate-infecting Plasmodium spp. are also circulating in Cameroon. A decline of artemisinin-based combinations therapeutic efficacy from 97% in 2006 to 90% in 2016 have been reported. Several mutations in the P. falciparum chloroquine resistance (Pfcrt) and P. falciparum multidrug resistance 1 (Pfmdr1) genes conferring resistance to either 4-amino-quinoleine, mefloquine, halofanthrine and quinine have been documented. Mutations in the Pfdhfr and Pfdhps genes involved in sulfadoxine-pyrimethamine are also on the rise. No mutation associated with artemisinin resistance has been recorded. Sixteen anopheline species contribute to malaria parasite transmission with six recognized as major vectors: An. gambiae, An. coluzzii, An. arabiensis, An. funestus, An. nili and An. moucheti. Studies conducted so far, indicated rapid expansion of DDT, pyrethroid and carbamate resistance in An. gambiae, An. coluzzii, An. arabiensis and An. funestus threatening the performance of LLINs. This review highlights the complex situation of malaria in Cameroon and the need to urgently implement and reinforce integrated control strategies in different epidemiological settings, as part of the substantial efforts to consolidate gains and advance towards malaria elimination in the country

Antibody responses to the full-length VAR2CSA and its DBL domains in Cameroonian children and teenagers

Additional file 2. IgG levels to VAR2CSA domains in 10–15 year old Cameroonian girls living in Ngali II and Ntouessong villages. IgG levels to VAR2CSA DBL domains and full-length protein (FV2) were measured in 11–15 year old girls residing in Ngali II and Ntouessong villages. DBL1 domain was from 3D7 strain and all the other proteins from FCR3 parasite strain. Median MFI and Inter-Quartile Range (IQR) are plotted

Assessing the Tsetse Fly Microbiome Composition and the Potential Association of Some Bacteria Taxa with Trypanosome Establishment

The tsetse flies, biological vectors of African trypanosomes, harbour a variety of bacteria involved in their vector competence that may help in developing novel vector control tools. This study provides an inventory of tsetse bacterial communities in Cameroon and explores their possible associations with trypanosome establishment in Glossina palpalis palpalis. High throughput sequencing of the V3-V4 hypervariable region of the bacterial 16S rRNA gene, with subsequent metagenomic, multivariate, and association analyses, were used to investigate the levels and patterns of microbial diversity in four tsetse species. Overall, 31 bacterial genera and four phyla were identified. The primary symbiont Wigglesworthia dominated almost all the samples, with an overall relative abundance of 47.29%, and seemed to be replaced by Serratia or Burkholderia in some G. tachinoides flies. Globally, significant differences were observed in the microbiome diversity and composition among tsetse species and between teneral and non-teneral flies, or between flies displaying or not displaying mature trypanosome infections. In addition, differential abundance testing showed some OTUs, or some bacteria taxa, associated with trypanosome maturation in tsetse flies. These bacteria could be further investigated for an understanding of their mechanism of action and alternatively, transformed and used to block trypanosome development in tsetse flies

Role of Anopheles (Cellia) rufipes (Gough, 1910) and other local anophelines in human malaria transmission in the northern savannah of Cameroon: a crosssectional survey

Background As part of a study to determine the impact of insecticide resistance on the effectiveness of longlasting insecticide treated nets (LLINs) in the north of Cameroon, the unexpectedly high density and anthropophilic behaviour of Anopheles rufipes lead us to investigate this species bionomics and role in human malaria parasite transmission. Methods For four consecutive years (2011–2014), annual cross-sectional sampling of adult mosquitoes was conducted during the peak malaria season (September-October) in three health districts in northern Cameroon. Mosquitoes sampled by human landing catch and pyrethrum spray catch methods were morphologically identified, their ovaries dissected for parity determination and Anopheles gambiae siblings were identified by molecular assay. Infection with P. falciparum and blood meal source in residual fauna of indoor resting anopheline mosquitoes were determined by enzyme-linked-immunosorbent assays. Results Anopheles gambiae (sensu lato) (s.l.) comprised 18.4% of mosquitoes collected with An. arabiensis representing 66.27% of the sibling species. The proportion of An. rufipes (2.7%) collected was high with a humanbiting rate ranging between 0.441 and 11.083 bites/person/night (b/p/n) and an anthropophagic rate of 15.36%. Although overall the members of An. gambiae complex were responsible for most of the transmission with entomological inoculation rates (EIR) reaching 1.221 infective bites/person/night (ib/p/n), An. arabiensis and An.coluzzii were the most implicated. The roles of An. funestus, An. pharoensis and An. paludis were minor. Plasmodium falciparum circumsporozoite protein rate in Anopheles rufipes varied from 0.6 to 5.7% with EIR values between 0.010 and 0.481 ib/p/n Conclusions The study highlights the epidemiological role of An. rufipes alongside the members of the An.gambiae complex, and several other sympatric species in human malaria transmission during the wet season in northern Cameroon. For the first time in Cameroon, An. rufipes has been shown to be an important local malaria vector, emphasising the need to review the malaria entomological profile across the country as pre-requisite to effective vector management strategies

Role of Anopheles (Cellia) rufipes (Gough, 1910) and other local anophelines in human malaria transmission in the northern savannah of Cameroon: a crosssectional survey

Background As part of a study to determine the impact of insecticide resistance on the effectiveness of longlasting insecticide treated nets (LLINs) in the north of Cameroon, the unexpectedly high density and anthropophilic behaviour of Anopheles rufipes lead us to investigate this species bionomics and role in human malaria parasite transmission. Methods For four consecutive years (2011–2014), annual cross-sectional sampling of adult mosquitoes was conducted during the peak malaria season (September-October) in three health districts in northern Cameroon. Mosquitoes sampled by human landing catch and pyrethrum spray catch methods were morphologically identified, their ovaries dissected for parity determination and Anopheles gambiae siblings were identified by molecular assay. Infection with P. falciparum and blood meal source in residual fauna of indoor resting anopheline mosquitoes were determined by enzyme-linked-immunosorbent assays. Results Anopheles gambiae (sensu lato) (s.l.) comprised 18.4% of mosquitoes collected with An. arabiensis representing 66.27% of the sibling species. The proportion of An. rufipes (2.7%) collected was high with a humanbiting rate ranging between 0.441 and 11.083 bites/person/night (b/p/n) and an anthropophagic rate of 15.36%. Although overall the members of An. gambiae complex were responsible for most of the transmission with entomological inoculation rates (EIR) reaching 1.221 infective bites/person/night (ib/p/n), An. arabiensis and An.coluzzii were the most implicated. The roles of An. funestus, An. pharoensis and An. paludis were minor. Plasmodium falciparum circumsporozoite protein rate in Anopheles rufipes varied from 0.6 to 5.7% with EIR values between 0.010 and 0.481 ib/p/n Conclusions The study highlights the epidemiological role of An. rufipes alongside the members of the An.gambiae complex, and several other sympatric species in human malaria transmission during the wet season in northern Cameroon. For the first time in Cameroon, An. rufipes has been shown to be an important local malaria vector, emphasising the need to review the malaria entomological profile across the country as pre-requisite to effective vector management strategies

Diversity and behavioral activity of Anopheles mosquitoes on the slopes of Mount Cameroon.

BACKGROUND: Malaria remains endemic in Cameroon, with heterogeneous transmission related to eco-climatic variations, vector diversity and spatial distribution. The intensification of malaria prevention and control through the free distribution of insecticide-treated nets in recent years may have altered the composition, geographic distribution and natural infection rate of Anopheles species, with implications for malaria transmission dynamics. The present study seeks to assess the vectorial diversity, dynamics and infectivity across different seasons and altitudes in relationship to parasite prevalence around the slopes of Mount Cameroon, southwestern region. METHOD: Mosquitoes were sampled (indoors and outdoors) in 11 eco-epidemiological settings at low (18-197 m), intermediate (371-584 m) and high (740-1067 m) altitude by nightly human landing catches. The mosquitoes were identified morphologically and Anopheles gambiae sibling species identified by PCR. Parity status was ascertained by examining the ovaries and the entomological inoculation rates (EIR) determined by Plasmodium falciparum circumsporozoite antigen ELISA of the head-thorax. The prevalence of Plasmodium infection across target communities was assessed using rapid diagnostic tests. RESULTS: A total of 7327 (18.0 mosquitoes/trap/night) mosquitoes were trapped, mainly during the rainy season (5678, 77.5%) and at low altitude (3669, 50.1%). Anopheles spp. (5079, 69.3%) was the most abundant genera and An. gambiae complex (2691, 36.7%) the major vector, varying with altitude (χ2 = 183.87, df = 8, P < 0.001) and season (χ2 = 28.14, df = 4, P < 0.001). Only An. gambiae (s.s.) was identified following molecular analysis of An. gambiae complex siblings. The overall biting peak for An. gambiae complex was 2-3 a.m. Anopheles cinctus was the most abundant secondary vector in the area. The average EIR in the area was 2.08 infective bites per person per night (ib/p/n), higher at low (2.45 ib/p/n) than at intermediate altitude (1.39 ib/p/n) and during the rainy (1.76 ib/p/n) compared to the dry season (0.34 ib/p/n). Anopheles funestus was most infectious overall (28.1%, 16/57) while An. gambiae had the highest inoculation rates averaging 1.33 ib/p/n. Most Anopheles species across all altitudes and seasons were parous, highest in communities with the highest proportion of malaria parasite infections. CONCLUSION: Anopheles gambiae (s.s.) remains the major malaria vector in the area and An. cinctus possibly a secondary vector of the disease in the slopes of Mt. Cameroon. The seasonal and altitudinal effects on the distribution of these mosquitoes may have implications for the transmission of malaria and its control strategies in the area. Regular monitoring of the bionomics of local Anopheles vector species and targeted control interventions in the 'hotspots' is necessary to curb the prevalence of the infection and incidence of disease