Hengki Tasman

A with-in host Dengue infection model with immune response

A model of viral infection of monocytes population by Dengue virus is formulated here. The model can capture phenomena that dengue virus is quickly cleared in approximately 7 days after the onset of the symptoms. The model takes into account the immune response. It is shown that the quantity of free virus is decreasing when the viral invasion rate is increasing. The basic reproduction ratio of model without immune response is reduced significantly by adding the immune response. Numerical simulations indicate that the growth of immune response and the invasion rate are very crucial in identification of the intensity of infection.

An optimal control strategy to reduce the spread of malaria resistance

This paper presents a mathematical model of malaria transmission considering the resistance of malaria parasites to the anti-malarial drugs. The model also incorporates mass treatment and insecticide as control strategies. We consider the sensitive and resistant strains of malaria parasites in human and mosquito populations. First, we investigated the existence and stability of equilibria of the model without control based on two basic reproduction ratios corresponding to the strains. Then, the Pontryagins Maximum Principle is applied to derive the necessary conditions for optimal control. Simulation results show the effectiveness of the optimal control to reduce the number of infected hosts and vectors.

An Optimal Treatment Control of TB-HIV Coinfection

An optimal control on the treatment of the transmission of tuberculosis-HIV coinfection model is proposed in this paper. We use two treatments, that is, anti-TB and antiretroviral, to control the spread of TB and HIV infections, respectively. We first present an uncontrolled TB-HIV coinfection model. The model exhibits four equilibria, namely, the disease-free, the HIV-free, the TB-free, and the coinfection equilibria. We further obtain two basic reproduction ratios corresponding to TB and HIV infections. These ratios determine the existence and stability of the equilibria of the model. The optimal control theory is then derived analytically by applying the Pontryagin Maximum Principle. The optimality system is performed numerically to illustrate the effectiveness of the treatments.

A Dengue Vaccination Model for Immigrants in a Two-Age-Class Population

We develop a model of dengue transmission with some vaccination programs for immigrants. We classify the host population into child and adult classes, in regards to age structure, and into susceptible, infected and recovered compartments, in regards to disease status. Since migration plays important role in disease transmission, we include immigration and emigration factors into the model which are distributed in each compartment. Meanwhile, the vector population is divided into susceptible, exposed, and infectious compartments. In the case when there is no incoming infected immigrant, we obtain the basic reproduction ratio as a threshold parameter for existence and stability of disease-free and endemic equilibria. Meanwhile, in the case when there are some incoming infected immigrants, we obtain only endemic equilibrium. This indicates that screening for the immigrants is important to ensure the effectiveness of the disease control.

Modeling mass drug treatment and resistant filaria disease transmission

It has been indicated that a long term application of combined mass drug treatment may contribute to the development of drug resistance in lymphatic filariasis. This phenomenon is not well understood due to the complexity of filaria life cycle. In this paper we formulate a mathematical model for the spread of mass drug resistant in a filaria endemic region. The model is represented in a 13-dimensional Host-Vector system. The basic reproductive ratio of the system which is obtained from the next generation matrix, and analysis of stability of both the disease free equilibrium and the coexistence equilibria are shown. Numerical simulation for long term dynamics for possible field conditions is also shown.

Implementation of regularized Markov clustering algorithm on protein interaction networks of schizophrenia's risk factor candidate genes

Schizophrenia has been suffered by over 21 million people worldwide. Genetic and environmental issues are one of the contributing factors in the development of this disease. Some research shown that several related genes may increase the risk of this disease. Candidate genes that obtained from several research turns up linked in a large network of protein-protein interaction (PPI). Therefore, it is necessary to study the PPI network of the candidate genes. Regularized Markov Clustering Algorithm (RMCL) is a graph clustering method which is the modification of Markov Clustering Algorithm (MCL). RMCL process that is built using R programming language is applied to PPI networks of schizophrenias risk factors candidate genes data obtained from BioGRID database. RMCL algorithm simulation performed with different parameter of inflation. Then, the results of RMCL algorithm simulation is compared to MCL algorithm simulation with the same parameters. RMCL algorithm provides results in the form of overlapping clusters, which mean there are relation between clusters. Thus, based on the results of RMCL algorithm simulation, there are relation between protein clusters of several candidate genes, one of which is the relation of NRG1 and CACNG2 gene product.

A mathematical model for long-term effect of diethylcarbamazine-albendazole mass drug administration on lymphatic filariasis

In this paper we discuss a mathematical model for the transmission of lymphatic filariasis disease. The human population is divided into susceptible, latent, acute and chronic subpopulations. Treatment is carried out within the scheme of mass drug administration (MDA) by giving the diethylcarbamazine (DEC) and albendazole (ALB) to all individuals. In the model, we assume that the treatments have direct killing effect to microfilariae, increase of immune-mediated effect. The treated individuals are assumed to remain susceptible to the disease. This is due to the fact that the treatment is only partially effective against macrofilaria. Simulations of the model reveals that DEC-ALB treatment does give significant reduction of acute and chronic compartments at the end of the treatment period and slow down the growth after the treatment before eventually tend to the endemic state. It showed that repeated treatment during MDA is effective to decrease the transmission. This suggests that terminating MDA program ...

A mass treatment model for endemic reduction of filaria disease with pre-testing

In 2000 WHO had issued a Global Program to Eliminate Lymphatic Filariasis by 2020. Lymphatic Filariasis is an infectious disease that may cause permanent disability to the infected human. This disease is caused by parasitic worms and transmitted by mosquitoes. In the acute cases, the infected persons will undergo swelling in parts of their body. One of the treatment which has been successfully implemented in some countries is the Diethylcarbamazine (DEC) mass treatment. This treatment, which was implemented every year for the period of few years in some endemic region, is able to kill microfilaria within human body and partially kills the macro filaria. In this paper, a host-vector model for transmission of filariasis is constructed, in which all non-chronic individuals are separated in different compartments. Stability analysis of the disease-free equilibrium and the existence of the endemic equilibria are shown. Numerical analysis and simulation will be conducted to estimate the effectiveness of treatme...