Parameter Estimation and Optimal Control of the Dynamics Of Transmission of Tuberculosis with Application to Cameroon

This paper deals with the problem of parameter estimation and optimal control of a tuberculosis (TB) model with seasonal fluctuations. We first present a uncontrolled TB model with seasonal fluctuations. We present the theoretical analysis of the uncontrolled TB model without seasonal fluctuations. After, we propose a numerical study to estimate the unknown parameters of the TB model with seasonal fluctuations according to demographic and epidemiological data from Cameroon. Simulation results are in good accordance with the seasonal variation of the new active reported cases of TB in Cameroon. Using this TB model with seasonality, the tuberculosis control is formulated and solved as an optimal control problem, indicating how control terms on the chemoprophylaxis and treatment should be introduced in the considered TB model to reduce the number of individuals with active TB. Results provide a framework for designing cost-effective strategies for TB with two strategies of intervention

Evaluation of Ensiled Brewer's Grain in the Diet of Piglets by One Way Multiple Analysis of Variance, MANOVA

The basic purpose of feeding trials is to find the optimum level of feed ingredients which give the highest economical returns to the farmers. This can be achieved through estimation and comparison of means of different rations. The example we have is a study of incorporation of different levels of ensiled brewers grains in the diet of 24 hybrids weaned piglets from Landrace x Duroc x Berkshire x Large White. They were randomly divided into four groups with three replicates of two piglets per pen. They were fed 0, 10, 20, 30% incorporation of ensiled brewer's grains on dry matter basis during post-weaning period followed by 0, 30, 40 and 50% during growing period and 0, 50, 60 and 70% during finishing period. We have one explanatory variable: initial weight, and four post treatment outcome variables recorded per piglets: final weight, dry matter consumption, weight gain and index of consumption. Comparing of several multivariate treatment means model design analysis is adapted. We obtain the MANOVA (Multiple Analyse of Variance) table of each phase, where the treatment differences exist by using Wilk's lambda distribution, and we find the treatment effect by using a confidence interval method of MANOVA. This model has the advantage of computing the responses of all variables in the matrix of sum of squares and more precisely in separation of the different means percentage of Ensiled Brewer's grain

Viral Dynamics of Delayed CTL-inclusive HIV-1 Infection Model With Both Virus-to-cell and Cell-to-cell Transmissions

We consider a mathematical model that describes a viral infection of HIV-1 with both virus-tocell and cell-to-cell transmission, CTL response immune and four distributed delays, describing intracellular delays and immune response delay. One of the main features of the model is that it includes a constant production rate of CTLs export from thymus, and an immune response delay. We derive the basic reproduction number and show that if the basic reproduction number is less than one, then the infection free equilibrium is globally asymptotically stable; whereas, if the basic reproduction number is greater than one, then there exist a chronic infection equilibrium, which is globally asymptotically stable in absence of immune response delay. Furthermore, for the special case with only immune response delay, we determine some conditions for stability switches of the chronic infection equilibrium. Numerical simulations indicate that the intracellular delays and immune response delay can stabilize and/or destabilize the chronic infection equilibrium

Effect of Carica papaya (Linn) aqueous leaf extract on pharmacokinetic profile of ciprofloxacin in rabbits

Purpose: To investigate the fate of ciprofloxacin, after concomitant administration with the aqueous leaf extract of Carica papaya, which herbal practitioners in Nigeria have found helpful in the treatment of painful crisis in sickle cell anaemia (SCA) patients.Method: Thirteen rabbits were fasted for 12 h and given by oral route 20 mg/kg ciprofloxacin (control group); after a 3-week crossover period, the animals were given 500 mg/kg aqueous extract of Carica papaya followed by 20 mg/kg ciprofloxacin (treatment group). Blood samples were collected over a period of 0 - 24 h post-dosing, and pharmacokinetic profile of ciprofloxacin in plasma sample determined using a validated high performance liquid chromatography (HPLC) method.Results: Time to attain maximum plasma ciprofloxacin concentration (Tmax), lag time and clearance (CL/F) were higher in the treated group; all other pharmacokinetic parameters showed significant decrease in the treated group (p < 0.005) compared to the control group. The slow rate of elimination of ciprofloxacin in the control group (0.32 ± 0.11 h-1) compared to the treated group (0.21 ± 0.07 h-1) was not due to kidney impairment as plasma creatinine level indicated that kidney function was within normal range (0.68 ± 2.78 mg/dl).Conclusion: The results of the study show that there is interaction between ciprofloxacin and Carica papaya. This interaction can be avoided by taking ciprofloxacin at least 3 h prior to administration of the leaf extract of C. papaya.Keywords: Carica papaya, Ciprofloxacin, Sickle cell anaemia, Herb-drug interaction, Pharmacokinetic

A metapopulation model for the population dynamics of anopheles mosquito

Please read abstract in the article.This article was co-written by B. Tsanou before he joined the University of Pretoria.http://www.elsevier.com/ locate/amchj2021Mathematics and Applied Mathematic

Etude préliminaire de l’infestation des glossines par les trypanosomes dans le baï de Momba (Nord-Est Gabon)

Une étude préliminaire entomo-parasitologique a été effectuée pendant la grande saison sèche à l’interieur et autour du baï de Momba (nord-est Gabon) pour examiner les espèces de Trypanosomes transmises par les glossines. Ces dernières ont été capturées à l’aide des pièges vavoua et nzi. Les infections par les trypanosomes chez ces glossines ont été recherchées à l’aide d’un microscope au niveau des glandes salivaires, proboscis et intestins moyens des glossines. Ainsi, une infection du proboscis seul correspond à T. vivax, celles des glandes salivaires à T. brucei et celle du proboscis et de l’intestin moyen à T. congolense. Au total six espèces de glossines ont été identifiées : Glossina palpalis palpalis, G. nashi, G. fusca congolensis, G. tachinoides, G. frezili et G. fuscipes fuscipes. Le taux global d’infestation des glossines disséquées et observées au microscope a été estimé à 30 %. L’infestation des glossines par les trypanosomes témoigne de l’existence d’un risque trypanosomien dans le baï de Momba et suggère ainsi l’établissement d’un cycle de transmission Animal-Glossine-Homme dans ce milieu.Mots clés: Glossina, T. vivax, T. congolense, baï de Momba, trypanosomes. Preliminary study of infection of tsetse by trypanosomes in the baï of Momba North East GabonA preliminary study are insect parasitology was carried out during the long dry season in and around the baï of Momba (north-east Gabon) to examine the species of trypanosomes transmitted by tsetse flies. The flies were captured using traps and Vavoua nzi. Infections by trypanosomes were investigated using a microscope in the salivary glands and the proboscis intestines means tsetse. In total six tsetse species were identified : Glossina palpalis palpalis, G. nashi, G. fusca congolensis, G. tachinoides, G. frezili and G. fuscipes fuscipes. The overall rate of infestation of flies dissected and observed under the microscope is estimated at 30 %. The infestation of Bai Momba by flies carrying trypanosomes demonstrates the existence of a trypanosome risk and thus suggests the establishment of a transmission cycle Human-Animal-Glossina in this environment.Keywords: tsetse flies, T. vivax, T. congolense, baï of Momba, trypanosome

Pesticides use in cocoa sector in Cameroon: characterization of supply source, nature of actives ingredients, fashion and reasons for their utilization

The chemical control is the widely control method applied in Cameroon for pests and diseases by all the cocoa producers without technical suitable assistance by the State as before 1980’S. However, it is known that farmers have less knowledge on the good pesticides use for the control of a specific pest. The objective of this study was to provide insight in current pesticide use in the cocoa sector in Cameroon. A stratified sampling scheme was used. A total of 251 cocoa farmers, 20 post-harvest cocoa traders and 37 chemical retailers were randomly selected and interviewed. The study showed that 35 different chemicals were marketed in Cameroon for use in cocoa: 4 herbicides, 11 fungicides and 20 insecticides. Of 251 farmers consulted, 96.8% said that they use pesticides on their farms while 3.2% did not. Fungicides were used most often by farmers 61.8%) followed by insecticides (38.2%). Eight active ingredients although, officially banned, were still being used on cocoa farms. Over 77% of farmers do not respect the official spray recommendations for chemicals. Moreover, 64% do not respect recommended doses. Two main pesticide-supply-pathways exist in Cameroon: a legal and illegal supply chain, which provides 51% of pesticides to cocoa farmers, resulting in an estimated loss of value added tax for the Cameroonian government of about 550 000 to 2.4 million Euros per year. These results suggest that improved pests and diseases control by the State and raising farmer awareness about pesticide use in cocoa could greatly attribute to more sustainable cocoa economy in Cameroon.Keywords : Cocoa, pesticides, insecticides, fungicides, Cameroon

Genomic and Proteomic Studies on the Mode of Action of Oxaboroles against the African Trypanosome

SCYX-7158, an oxaborole, is currently in Phase I clinical trials for the treatment of human African trypanosomiasis. Here we investigate possible modes of action against Trypanosoma brucei using orthogonal chemo-proteomic and genomic approaches. SILAC-based proteomic studies using an oxaborole analogue immobilised onto a resin was used either in competition with a soluble oxaborole or an immobilised inactive control to identify thirteen proteins common to both strategies. Cell-cycle analysis of cells incubated with sub-lethal concentrations of an oxaborole identified a subtle but significant accumulation of G2 and >G2 cells. Given the possibility of compromised DNA fidelity, we investigated long-term exposure of T. brucei to oxaboroles by generating resistant cell lines in vitro. Resistance proved more difficult to generate than for drugs currently used in the field, and in one of our three cell lines was unstable. Whole-genome sequencing of the resistant cell lines revealed single nucleotide polymorphisms in 66 genes and several large-scale genomic aberrations. The absence of a simple consistent mechanism among resistant cell lines and the diverse list of binding partners from the proteomic studies suggest a degree of polypharmacology that should reduce the risk of resistance to this compound class emerging in the field. The combined genetic and chemical biology approaches have provided lists of candidates to be investigated for more detailed information on the mode of action of this promising new drug clas

Socio-economic Benefits of Non-timber Forest Products to the AFCOE2M Communities of Southern Cameroon

A study was carried out in the community forest of Ebo, Medjounou and Mbamesoban communities (AFCOE2M) in the South Region of Cameroon to evaluate the contribution of non-timber forest products (NTFPs) to the people’s livelihood. The study identifies the various NTFPs used and further evaluates their socio-economic and cultural contributions in sustaining the livelihood of the AFCOE2M community. Essentially, the study assesses the exploitation and utilization of NTFPs. One Hundred and twenty five (125) individuals were randomly selected in the three villages that make up the AFCOE2M community forest. Fifty two (52) species of NTFPs of plant origin were identified, from which seven (7) were frequently used in all the three villages namely; Irvingia gabonensis, Trichoscypha acuminata, Alstonia boonei, Garcinia kola, Piper guineense, Picralima nitida, and Ricinodendron heudelotii. Results reveal that NTFPs plant parts used for consumption consist of 68% fruits, 20% seeds, 5% barks, 4% roots and 3% leaves. NTFPs used for medicinal purposes comprised of 70% barks, 16% seeds, 7% leaves, 5% fruits and 2% roots. There was a significant difference (P = 0.049) in the number of NTFP types consumed as food while that was not the case for medicinal NTFPs (P = 0.86). There was a significant difference in the number of NTFP species used for food originating from different land use types (P-value = 0.048) as well as between those used for medicinal purposes (P-value = 0.012)

EVALUATION NATURELLE DE L\u2019IMPACT DE BEAUVERIA BASSIANA : CHAMPIGNON ENTHOMOPATHOG\uc9NE DANS LA DYNAMIQUE DE POPULATION DE HYPOTHENEMUS HAMPEI , SCOLYTE DE BAIES DES CERISES DE COFFEA CANEFORA COFFEA CANEFORA

A study of finding out natural enemies of the coffee cherry borer beetle Coffea canephora , Hypothenemus hampei (Ferrari) (Coleoptera, Scolytidae) was carried out at two ecologically different sites of Cameroon: Nkoemvone in the South region of the country and Nkolbisson around Yaound\ue9 in the central region. For six months, 500 berries were randomly collected monthly at each site. The presence of entomopathogenic fungus was observed on berries infested by the borer beetle. Rates of borer insect mortality due to Bauveria bassiana at Nkoemvone are: 70.6% in August, 64.6% in September, 32% in October, 43.2% in November, 39.2% in December and very low in January (8.6%). On the other hand, these rates at Nkolbisson are: 42.6% in October, 10% in November, 3.4% in December, 2.6% in January, 1.4% in February and 0% in March. From these observations, it was possible to carry out a research on the pathogenicity tests through its natural presence and on artificial-infection trials of the borer beetle with this fungus in order to protect better the coffee grains with a biological product.Une \ue9tude de recherche des ennemis naturels contre le scolyte des cerises de caf\ue9ier Coffea canephora , Hypothenemus hampei (Ferrari) (Coleoptera, Scolytidae), a \ue9t\ue9 men\ue9e dans deux sites au Cameroun : Nkoemvone une r\ue9gion du Sud du pays et Nkolbisson pr\ue8s de Yaound\ue9, une r\ue9gion du centre. Pendant six mois, 500 baies \ue9taient mensuellement pr\ue9lev\ue9es de mani\ue8re al\ue9atoire dans chaque site. La pr\ue9sence du champignon entomopathog\ue8nes a \ue9t\ue9 observ\ue9e sur les baies attaqu\ue9es par les scolytes. Les taux de mortalit\ue9 du scolyte due \ue0 Bauveria bassiana \ue0 Nkoemvone sont de 70,6 en ao\ufbt, 64,6% en septembre, 32% en octobre, 43,2% en Novembre, 39,2% en d\ue9cembre et tr\ue8s faible en janvier (8,6%). Par contre ce taux \ue0 Nkolbisson est de 42,6% en octobre, 10% en Novembre, 3,4% en d\ue9cembre, 2,6%en janvier, 1,4% en f\ue9vrier et 0% en Mars. A partir de ces observations, il a \ue9t\ue9 possible de proposer par sa pr\ue9sence naturel une cherche sur le test de pathogenicit\ue9 et des essais d\u2019infection artificielle du scolyte avec ce champignon \ue0 fin mieux prot\ue9ger les grains de caf\ue9ier avec un produit biologique