Browsing by Author "Chuma, Furaha"

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Application of Optimal Control Theory to Newcastle Disease Dynamics in Village Chicken by Considering Wild Birds as Reservoir of Disease Virus
(Hindawi, 2019-03-03) Chuma, Furaha; Mwanga, Gasper Godson; Masanja, Verdiana Grace
In this study, an optimal control theory was applied to a nonautonomous model for Newcastle disease transmission in the village chicken population. A notable feature of this model is the inclusion of environment contamination and wild birds, which act as reservoirs of the disease virus. Vaccination, culling, and environmental hygiene and sanitation time dependent control strategies were adopted in the proposed model. This study proved the existence of an optimal control solution, and the necessary conditions for optimality were determined using Pontryagin’s Maximum Principle. The numerical simulations of the optimal control problem were performed using the forward–backward sweep method. The results showed that the use of only the environmental hygiene and sanitation control strategy has no significant effect on the transmission dynamics of the Newcastle disease. Additionally, the combination of vaccination and environmental hygiene and sanitation strategies reduces more number of infected chickens and the concentration of the Newcastle disease virus in the environment than any other combination of control strategies. Furthermore, a cost-effective analysis was performed using the incremental cost-effectiveness ratio method, and the results showed that the use of vaccination alone as the control measure is less costly compared to other control strategies. Hence, the most effective way to minimize the transmission rate of the Newcastle disease and the operational costs is concluded to be the timely vaccination of the entire population of the village chicken, improvement in the sanitation of facilities, and the maintenance of a hygienically clean environment.
Bacterial Diversity Dynamics in Sandy Loam Soils in Tanzania Under Varying Fertilizer-Derived Uranium Concentrations
(Microorganisms, 2025-08-13) Mwalongo, Dennis; Lisuma, Jacob; Haneklaus, Nils; Maged, Ali; Brink, Hendrik; Carvalho, Fernando; Wacławek, Stanisław; Mpumi, Nelson; Amasi, Aloyce; Mwimanzi, Jerome; Chuma, Furaha; Kivevele, Thomas; Mtei, Kelvin
The presence of radiotoxic uranium (U) in mineral fertilizers is of global concern. A pilot study was conducted in Tabora (Tanzania) to determine the release of U from three brands of phosphate fertilizers and its impact on soil bacteria. The experiment used three types of fertilizer: Minjingu Powder (MP), Nafaka Plus (NP), a mixed and granulated fertilizer made from Minjingu Phosphate Rock (MPR), and YaraMila Cereal (YC) fertilizer. There was also a control treatment that was not fertilized (NF). Alpha diversity and the R tool were used to analyze bacterial diversity in four samples within an average sequencing depth of 74,466 reads, using metrics like ASVs, Shannon index, and Chao1. The results showed that the number of amplicon sequence variants (ASVs) in the DNA from soil bacteria decreased, specifically to 400 ASVs, in the NP treatment, which was in line with the higher U concentration (3.93 mg kg−1) in the soils. In contrast, the MP fertilizer treatment, associated with a lower U concentration (3.06 mg kg−1) in soils, exhibited an increase in ASVs within the DNA of soil bacteria, reaching 795; the highest ASV value (822) was observed in the NF treatment. Higher amounts of U in the soil plots seemed to have resulted in more types of bacteria, with the Actinobacteriota phylum being the most common in all of the treatments. The NP (3.93 mg kg−3 U concentration) and MP (3.06 mg kg−3 U concentration) treatments were the only ones that showed Halobacteriota and Crenarchaeota phyla. Nonetheless, bacterial diversity may also account for the alterations in soil phosphorus and nitrogen following fertilizer application. The YaraMila Cereal treatment did not seem to be linked to any particular bacterial phylum. This means that in this study it did not have any measurable effect on the soil bacteria species compared to the MP and NP treatments
Modeling the dynamics, control and economic loss of newcastle disease in village chicken: a case of Pwani region in Tanzania
(2019-03) Chuma, Furaha
Newcastle disease (ND) is a highly contagious viral bird disease affecting the domestic and other wild birds. The disease is a major threat to the farming of village chicken by small, medium, and large scale farmers. In this dissertation, a non-linear deterministic mathematical model of ND to study the dynamics, control and the economic loss of the village poultry with village chicken population, wild birds population of virus in the environment is formulated and analyzed. The basic reproduction number(R0) which represents the number of secondary cases where one case would produce in a completely susceptible population is derived using the Next Generation Matrix technique. The bifurcation analysis of the equilibrium points shows that a model exhibits the forward bifurcation meaning that the R0 less than a unit is a sufficient condition to reduce the transmission of ND in village chicken population. The sensitivity analysis of the parameters in R0 were computed using a normalized forward sensitivity analysis, results show that the transmission coefficient of the Newcastle disease virus between the hosts and the environment is found to be the most positive sensitive parameter in the model. A model is then extended to include three time dependent variables: vaccination, culling and the environmental hygiene and sanitation control strategies. To determine the best control strategy to mitigate the ND burden, the optimal control techniques are applied. The existence of the optimal control problem is proved with the necessary conditions for optimality determined using the Pontryagin’s Maximum Principle. Numerical simulations were performed using the forward-backward sweep iterative scheme of Runge-Kutta method of order four. Finally, a cost-effectiveness analysis is performed using the Incremental Cost-Effective Ratio (ICER). The results showed that the vaccination control strategy indicates the lowest cost compared to other control measures. The economic burden of the ND to chicken farmers, is considered as the total annual expenditure that a chicken farmer can incur to rescue the at risk chicken population from the ND is also investigated. The economic data of the model were collected from ten villages of Bagamoyo and Kibaha, Tanzania. Results from this study indicate that the recurrence of the ND in the village chicken population could lead to a serious economic loss at family level in this already financially constrained environment where small and medium farmers operate. The results obtained shows that there was 22:5% loss from their expected profit post Newcastle outbreaks in 2017. Also the results show that the occurrence of the ND leads to an average range of 482:89 􀀀 541:30$ economic loss at family in 2017. Therefore, for the effective control of NDV and its transmission we recommend vaccination to be paired with regular cleaning of chicken yards.
Uranium Dissemination with Phosphate Fertilizers Globally: A Systematic Review with Focus on East Africa
(MDPI, 2024-01-09) Mwalongo, Dennis; Haneklaus, Nils; Lisuma, Jacob; Mpumi, Nelson; Amasi, Aloyce; Mwimanzi, Jerome; Chuma, Furaha; Kivevele, Thomas; Mtei, Kelvin
Growing concern has been expressed about uranium (U) accumulation in agricultural soils caused by the long-term application of mineral fertilizers. More than 80% of naturally occurring U transfers from phosphate rock (PR), the raw material used in mineral fertilizer production, to phosphorus (P) fertilizers. These fertilizers are then distributed on agricultural soils, where the U could accumulate over time and become a risk to the environment. The objective of this work was to review the reported content of U in P fertilizers, its potential dispersion in soils, and its uptake by plants in different countries in the world as reported in the literature. The articles for this systematic review were selected from the Scopus database published between 2003 and 2022. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) protocol were used. A total of 54 articles were assessed based on the standard inclusion and exclusion criteria. U concentrations in P fertilizers, agricultural soil dissemination, and plant uptake for available data were obtained and assessed. In order to compare a set of related data from the collected articles, box and whisker plots showing the distribution of U in P fertilizers are presented by region. The results from the reviewed articles show that the U concentrations in P fertilizer were in the range of 0.1–653 mg kg−1. Interestingly, Minjingu P fertilizers from Tanzania, which are used in six East African countries, showed the highest U concentrations (159 to 653 mg kg−1, average 390 mg kg−1). The reported U concentrations for these fertilizers are, in fact, comparable to those of conventional low-grade uranium deposits mined in Namibia and elsewhere. Additionally, approximately 96% of the reviewed articles indicate that fertilized soil has higher U concentrations than non-fertilized soils, hinting at a measurable effect of mineral fertilizer use. The review recommends U extraction during mineral fertilizer production so that potential environmental risks can be reduced and U resources that would otherwise be lost can be recovered and used to substitute conventional U mining elsewhere.