Mosquito Death Research Articles

A deterministic mathematical model for quantifiable prediction of antimalarials limiting the prevalence of multidrug-resistant malaria

The malaria’s multidrug-resistant strain in Nigeria is prevalent and it poses a significant challenge for disease elimination. The testing for resistance is available but underutilized. Therefore, we develop a mathematical model incorporating the testing as a control strategy. This allows us to make quantifiable predictions about the effects of testing utilization on the malaria prevalence. By fitting the model to data on malaria and using field data reported in the literature, important parameters associated with the disease dynamics are estimated and calculated. First, we analyze the disease-free state of the malaria model and calculate the baseline control reproduction number. Sensitivity analysis is used to investigate the influence of the parameters in curtailing the disease. Numerical simulations are used to explore the behavior of the model solutions involving testing for resistance of the strain and wild strain malaria. We found that the implementation of testing would (a) prevent the increase of malaria prevalence from 30% to 35%, (b) significantly slow down the replacement of the wild strain by the resistant strain, and (c) avert about 6% of treatment failures. We also found that increasing mosquito death rate or reducing mosquito biting rate, mosquito birth rate, transmission to or from mosquitoes would contribute most significantly to the reduction of malaria prevalence in the community. In conclusion, the treatment failure is a significant component of the community malaria epidemic. Testing for multidrug resistance yields a significant reduction in cases with many implications regarding the containment of malaria in Nigeria.

Demonstration of RNAi Yeast Insecticide Activity in Semi-Field Larvicide and Attractive Targeted Sugar Bait Trials Conducted on Aedes and Culex Mosquitoes.

Eco-friendly new mosquito control innovations are critical for the ongoing success of global mosquito control programs. In this study, Sh.463_56.10R, a robust RNA interference (RNAi) yeast insecticide strain that is suitable for scaled fermentation, was evaluated under semi-field conditions. Inactivated and dried Sh.463_56.10R yeast induced significant mortality of field strain Aedes aegypti, Aedes albopictus, and Culex quinquefasciatus larvae in semi-field larvicide trials conducted outdoors in St. Augustine, Trinidad, where 100% of the larvae were dead within 24 h. The yeast was also stably suspended in commercial bait and deployed as an active ingredient in miniature attractive targeted sugar bait (ATSB) station sachets. The yeast ATSB induced high levels of Aedes and Culex mosquito morbidity in semi-field trials conducted in Trinidad, West Indies, as well as in Bangkok, Thailand, in which the consumption of the yeast resulted in adult female mosquito death within 48 h, faster than what was observed in laboratory trials. These findings support the pursuit of large-scale field trials to further evaluate the Sh.463_56.10R insecticide, a member of a promising new class of species-specific RNAi insecticides that could help combat insecticide resistance and support effective mosquito control programs worldwide.

SEIR Model of Dengue Hemorrhagic Fever with the Life Stage Structure of the Aedes albopictus Mosquito

Dengue Hemorrhagic Fever (DHF) is an acute febrile illness caused by the dengue virus. This virus belongs to group B arthropod-borne viruses (Arboviroses) of the genus Flavivirus, which has four serotypes, namely Dengue I, Dengue II, Dengue III, and Dengue IV. Dengue virus is transmitted by Aedes sp. The SEIR model studied places the Aedes albopictus mosquito as the main vector. Many DHF cases are caused by this mosquito because it has a larger coverage area and is more difficult to control. All Aedes mosquito species have four life stages, namely: (1) egg, (2) larva, (3) pupa, and (4) adult. A stage-structured model was chosen because Ae. albopictus has varying rates of development and mortality at different stages. This model study includes determining the fixed point, determining the basic reproduction number R0, analyzing the stability of the fixed point, and simulating the population dynamics of dengue virus transmission. This model indicates the presence of endemics in an area for certain parameter values. This model produces a disease-free equilibrium, or DFE, which will be stable when R0 < 1, otherwise unstable when R0 > 1. The dynamic results for each human population (susceptible, exposed, infected, and cured) through observations in numerical simulations are influenced by the selection of the R0 value. The value of R0 is influenced by the mosquito death rate parameter and the average bite rate of infected mosquitoes. Population dynamics simulations show that an increase in the death rate of mosquitoes will reduce the number of humans exposed to them. In addition, an increase in the average number of infected mosquito bites will increase the number of humans exposed. Changes in the number of humans in each population tend to be different for each increase in the mosquito mortality rate or for each increase in the average number of infected mosquito bites.
 

Aedes aegypti Argonaute 2 controls arbovirus infection and host mortality

Ae. aegypti mosquitoes transmit some of the most important human viral diseases that are responsible for a significant public health burden worldwide. The small interfering RNA (siRNA) pathway is considered the major antiviral defense system in insects. Here we show that siRNA pathway disruption by CRISPR/Cas9-based Ago2 knockout impaired the mosquitoes’ ability to degrade arbovirus RNA leading to hyper-infection accompanied by cell lysis and tissue damage. Ago2 disruption impaired DNA repair mechanisms and the autophagy pathway by altering histone abundance. This compromised DNA repair and removal of damaged cellular organelles and dysfunctional aggregates promoted mosquito death. We also report that hyper-infection of Ago2 knockout mosquitoes stimulated a broad-spectrum antiviral immunity, including apoptosis, which may counteract infection. Taken together, our studies reveal novel roles for Ago2 in protecting mosquitoes from arbovirus infection and associated death.

Analysis of dengue infection transmission dynamics in Nepal using fractional order mathematical modeling

Dengue is a significant factor to the global public health issue, including Nepal. In Nepal from 2004−2022, the largest outbreak occurred in the year 2022. Dengue infection cases appeared all over 77 districts of Nepal. The Caputo fractional order SEIR-SEI epidemic model is able to describe dengue disease transmission dynamics of present situation. For fundamental mathematical guarantees of epidemic model equations, we studied the Lipschitz and Banach contraction theorems to show that the model equations have a unique solution. The Ulam-Hyres stability is established in the model. Next generation matrix approach is used to calculate the associated basic reproduction number R0. The model equilibrium points are identified, and the local asymptotic stability for disease-free equilibrium point is analyzed. Normalized forward and partial rank correlation coefficient are used for sensitivity study to identify the factors that affect dengue infection with respect to basic reproduction number. Using real data of Nepal, the model is fitted and the least square method is used for estimating parameters. Numerical scheme has been illustrated using a two-step Lagrange interpolation approach and the solution is approximated. With numerical results and sensitivity analysis, it is concluded that biting rate and death rate of mosquito are extremely sensitive to the disease transmission. The transmission increases with increasing biting rate and decreases with decreasing mosquito death rate. For the year 2022, R0=1.7739>1 showing that the disease is endemic. Thus, effective control measure should be implemented to combat the dengue virus. However, further research needs to be undertaken to assess the impact of such control measures.

Exploring the Insecticidal Effect of Lemon Grass Juice on Mosquitoes

This experimental study was conducted to explore the insecticidal effect of lemon grass juice on the number of mosquitoes killed. The experiment was conducted at Baras, Dumangas Iloilo. A total of sixty mosquito larvae are bred to make adult mosquitoes and used in the experiment. Complete Randomized Design was employed with four treatments each, corresponding to 100% concentration of lemon grass juice, 50% concentration of lemon grass juice, commercial mosquito insecticide, and no treatment administered. Each treatment was replicated four times. Descriptive statistics such as mean, and standard deviation, and inferential statistics such as Analysis of Variance were utilized. Results showed that a 100% concentration of lemon grass juice has an insecticidal effect on mosquitoes. Considering that 100% lemon grass juice was the most effective, preservation of lemon grass at this level was recommended for commercial purposes. Further studies are recommended to be conducted to determine the active chemical component for the death of mosquitoes.

Uji Resistensi Vektor Demam Berdarah Dengue (DBD) Terhadap Insektisida Permethrin di Kota Binjai Provinsi Sumatera Utara Tahun 2022

The control effort of Dengue Hemorrhagic Fever (DHF) which is transmitted by the Aedes sp. infected with the Dengue virus, of which can be done by fogging. The active ingredient for fogging generally uses the insecticide permethrin. This study aimed to identify the resistance status of DHF vectors to the insecticide permethrin in controlling DHF vectors. The method of collecting Aedes sp. larvae was carried out in 100 residents' houses in neighborhoods 3 and 4 of Damai Village, North Binjai District, Binjai City, North Sumatra Province by observing each water reservoir that has the potential to become a breeding ground for Aedes sp. Aedes sp. larvae colonized until the F1 generation, then tested for resistance to permethrin insecticide using the CDC Bottle method. Data analysis was carried out descriptively. The percentage of death of test mosquitoes was 25% (<80%). It was concluded that the Aedes sp. in Neighborhoods 3 and 4 of Damai Village, North Binjai District, Binjai City were resistant to the insecticide permethrin. It is recommended that the Binjai City Health Office/Government make a policy in controlling the DHF vector by replacing Permethrin insecticide with another class of insecticides.

MODELING AND ANALYSIS OF LOW-LEVEL TRANSMISSION ZIKV DYNAMICS VIA A POISSON POINT PROCESS ON SEXUAL TRANSMISSION ROUTE

In this project, we modeled the low-level ZIKV transmission that was reported in Thailand [? ]. The secondary sexual transmission route is modeled by a Poisson point process, which leads to an increasing and saturating contact rate. This nonlinear contact rate further induces backward and Hopf bifurcations. Oscillations bifurcating from the Hopf bifurcation demonstrate the low-level persistent ZIKV transmission with sharp outbreaks, which further show varying amplitudes and frequency by considering stochastic variations on the sexual transmission rate. Global stability analysis of the diseasefree equilibrium drives the disease elimination criteria for models considering vector transmission route only and considering both vector and sexual transmission routes. Bifurcation analyses prove the existence of forward and backward bifurcations, saddle-node bifurcation, and Bogdanov-Takens analytically, and further suggest the occurrence of cusp, Hopf, and general Hopf bifurcations numerically. One and two-dimensional bifurcation diagrams demonstrate the analytical results under the influence of both vector and sexual transmission rates. Sensitivity analysis suggests that an increase in mosquito death rate has the largest effect on the basic reproduction number, and an increase in human recovery rate has the most influence on decreasing human host prevalence.

Evaluation of mosquitocidal potency of leaves and fruits extracts of Phyllanthus acidus L. against filarial vector Culex quinquefasciatus Say

The present piece of work was done to carry out larvicidal, pupicidal, adulticidal, and repellent activities of crude extracts of mature leaf and fruit extract of Phyllanthus acidus against filarial vector Culex quinquefasciatus. The percentage mortality of 1st instar stages of Cx. quinquefasciatus at 0.7% concentration was considerably higher (p < 0.05), followed by second, third and fourth instars larvae. Whereas crude extract of fruits showed 100% mortality at 0.9% concentration in case of first instar larvae of Cx. quinquefasciatus after 24 h of contact. The lowest LC50 value observed was 0.26 ml and 0.34 ml against the first instar larval stages of Cx. quinquefasciatus after exposure of 24 hours in crude leaf and fruit extract of P. acidus, respectively. In pupicidal bioassay, the crude leaves extract of P. acidus exhibited pupicidal potency with LC50 values of 7.463% after 24 h. The extract from fresh leaves of P. acidus revealed repellency against the mature females of Cx. quinquefasciatus with 94% protection. In adulticidal activity, after 24 h of exposure there is 93.3% death of adult mosquitoes of Cx. quinquefasciatus observed. ANOVA (three-way factorial) was done for both the crude extracts of plant parts and it showed a substantial variance in larval mortality (p

Effects of Vertical Transmission and Human Contact on Zika Dynamics

The main objective of Zika transmission studies is to work out the simplest approach to scale back human mortality and morbidity caused by the disease. Therefore, it is essential to spot the relative importance of the various factors contributing to the transmission and prevalence of the disease. Many mathematical models have been formulated incorporating vector‐to‐human transmission or human‐to‐human transmission. However, they do not take into consideration the mixture of both sorts of transmission. It raises the question of the impact of both sorts of transmission on the disease dynamics. We develop a mathematical model of Zika with the vertical transmission in the vector population and human‐to‐human transmission to answer this question. It includes the immature phase of mosquitoes (eggs), adult mosquitoes (susceptible, exposed, and infectious), and human hosts (susceptible, exposed, infectious, and recovered). Results show that neglecting sexual transmission results in an understatement of the proportion of the infected population. Furthermore, it reduces the speed of disease spreading. On the other hand, vertical transmission in mosquitoes has a negligible effect on the dynamics of disease spread. We perform a sensitivity analysis of the reproductive number R0 to raise to understand the parameters driving the dynamics of the disease. It appears that the most sensitive parameters in decreasing order are as follows: the adult mosquito death rate, the sting rate, the transmission probability of mosquito to human, and, therefore, the transmission probability of human to mosquito. Furthermore, the proportion at the equilibrium of infected humans is extremely sensitive to the transition rate from the immature vector stage to the adult stage, the human‐to‐human transmission rate, and, therefore, the human recovery rate. These results confirm that control policies targeting the vector population and, therefore, the recovery rate of people are pretty effective solutions. To validate the model and estimate the important parameters of the model and the prediction of the disease, we consider the real cases in Colombia from 2016. In a series of graphic maps, we presented the comparative study to estimate the disease scenarios and to predict the time limit of the epidemic control measure.

Resistensi Aedes aegypti Terhadap Insektisida: Studi pada Insektisida Rumah Tangga

Dengue hemorrhagic fever is a public health problem in Pekanbaru. It is transmitted by Aedes aegypti mosquitoes. The use of insecticides to kill vectors is a common practice. It is often used in outbreaks by fogging and daily use of insecticides in households. Household insecticides contain a variety of active ingredients such as organophosphates, carbamates, synthetic pyrethroids, and their combinations. This study aims to determine the sensitivity of Ae. aegypti mosquitoes from various household insecticides. This research was descriptive research by conducting a susceptibility test from World Health Organization. Adult mosquitoes were obtained from the breeding of larvae collected from dengue-endemic areas in Pekanbaru. Three types of insecticides are widely distributed in the market consisting of insecticides X with the active ingredient cypermethrin, transfluthrin, and imiprothrin, insecticide Y containing transfluthrin, and insecticide Z containing pralethrin and sifluthrin. Each insecticide was exposed to an adult mosquito by applying insecticides to filter paper and exposed for 1 hour and observed after 24 hours. The death of mosquitoes in the three types of insecticides is less than 80%. Based on the WHO criteria mortality of less than 80% showed a resistant mosquito. This tendency of resistance is probably caused by long-term continuous use.

Mathematical modeling of the impact of temperature variations and immigration on malaria prevalence in Nigeria

The study examines the population-level impact of temperature variability and immigration on malaria prevalence in Nigeria, using a novel deterministic model. The model incorporates disease transmission by immigrants into the community. In the absence of immigration, the model is shown to exhibit the phenomenon of backward bifurcation. The disease-free equilibrium of the autonomous version of the model was found to be locally asymptotically stable in the absence of infective immigrants. However, the model exhibits an endemic equilibrium point when the immigration parameter is greater than zero. The endemic equilibrium point is seen to be globally asymptotically stable in the absence of disease-induced mortality. Uncertainty and sensitivity analysis of the model, using parameter values and ranges relevant to malaria transmission dynamics in Nigeria, shows that the top three parameters that drive malaria prevalence (with respect to [Formula: see text]) are the mosquito natural death rate ([Formula: see text]), mosquito biting rate ([Formula: see text]) and the transmission rates between humans and mosquitoes ([Formula: see text]). Numerical simulations of the model show that in Nigeria, malaria burden increases with increasing mean monthly temperature in the range of 22–28[Formula: see text]. Thus, this study suggests that control strategies for malaria should be intensified during this period. It is further shown that the proportion of infective immigrants has marginal effect on the transmission dynamics of the disease. Therefore, the simulations suggest that a reduction in the fraction of infective immigrants, either exposed or infectious, would significantly reduce the malaria incidence in a population.

Transmission dynamics of zika virus in presence of vertical transmission and some preventive measures

Zika virus (ZIKV) infection is a vector-born human disease which enhances the chance of various types of neurological complications in affected individual. In this work we have studied a mathematical model of ZIKV by incorporating vector, direct (sexual) and vertical transmission paths of the virus. In our model also we have considered different kind of preventive measures like as: protection of susceptible individuals from mosquito bites, isolation of infected individuals from mosquito, protection of susceptible individuals from sexual interaction with infected individuals, and mosquitoes control effort. We have found the analytical expression of basic reproduction number and studied the stability of the disease free equilibrium point. Existence of endemic equilibrium point and its stability are also studied. The proposed model exhibits a backward bifurcation when the virus transmission probability from infected human to mosquito crosses the crucial value. We have fitted the model to real data and estimated the key model parameters and their 95% confidence interval which depict the ZIKV outbreak in French Polynesia in 2013-14. We also have estimated the basic reproduction number using first nine epidemic weeks (EW) data and the estimated value is 2.87 with lower and upper values are 2.47 and 3.32 respectively. The effective reproduction number of the outbreak also has been studied and which decreases gradually from 5.404 to 0.2499 during the period 11th October, 2013 and 28th March, 2014. According to our sensitivity analysis, the basic reproduction number is the most sensitive with controllable parameters, biting rate, mosquito recruitment rate, mosquito death rate and recovery rate from infection. Finally, numerically we have studied the impact of different parameters on the basic reproduction number and on the number of infected human population.

Discovery and mechanistic study of an &amp;lt;italic&amp;gt;Aedes aegypti&amp;lt;/italic&amp;gt; lethalbacteria &amp;lt;italic&amp;gt;Chromobacterium&amp;lt;/italic&amp;gt;

Mosquitoes are arthropod vectors for many pathogens, and mosquito-borne diseases have become a major human health and economic concern in recent years. There is a large amount of microbiota in the mosquito gut, which may influence multiple aspects of vector physiology, including reproduction, metabolism, and immunity. In this study, we mainly focus on mosquito-microbiota interactions. Among the 18 strains isolated from the Aedes aegypti midgut, we found that Chromobacterium , a gut commensal bacteria, could significantly decrease mosquito longevity. We fed specimens a sugar source containing Chromobacterium at a concentration of 2.78×108 CFU/mL, which resulted in the rapid mortality of Aedes aegypti and Aedes albopictus . Moreover, the entomopathogenic activity of Chromobacterium was dose-dependent. Mechanistic investigations revealed that Chromobacterium could impair the mosquito midgut barrier and increase midgut permeability, leading to the enrichment of bacteria in the hemolymph, thus accelerating mosquito death. Additionally, a components study revealed that proteins secreted by Chromobacterium led to mosquito death. The mosquitocidal activity of Chromobacterium makes it a potential candidate for the development of enhanced mosquito control strategies.

PEMANFAATAN EKSTRAK BUNGA KECOMBRANG (Etlingera elatior jack R.M.sm) SEBAGAI LARVASIDA NYAMUK (Culex quinquifasciatus Say)

This study aims to determine the effectiveness of kecombrang flower extract (Etlingera elatior jack R.M.sm) on the death of Culex quenquefasciatus Say larvae. Experimental animals used were Culex quenquefasciatus Say larvae, amounting to 625 tails. The design used was a randomized complete design with 5 treatments and 5 replications. The five treatments consisted of two test groups, namely the treatment group consisting of concentrations of 5%, 10%, 15%, and the control group consisting of positive control namely abate and negative control namely aquades. Observation of mosquito larvae death was done every 2 hours for 12 hours. The data obtained were analyzed using the one-way ANOVA test and continued with the Duncan test. Based on the results of the one way ANOVA calculation the value of sig.0.00 &lt;0.05 means that there are significant differences between treatments. Duncan test results on the treatment of 10% and 15% kecombrang flower extract have the ability as a larvicide high and equal to positive control (abate). Based on the results of the study it was concluded that the extract of kecombrang flower (Etlingera elatior jack R.M.sm) had the ability to larvae against the Culex quenquefasciatus Say mosquito.

Analisis Ekstrak Kulit Batang Tanaman Biduri Terhadap Kematian Jentik Nyamuk Aedes Aegypti

Nyamuk adalah ektoparasit pengganggu yang merugikan kesehatan, manusia, hewan, dan lingkungan. Hal ini dikarenakan kemampuannya sebagai vektor berbagai penyakit. Salah satu pengendalian yang dapat dilakukan adalah dengan penggunanaan insektisida hayati yaitu tanaman Calontopis gigantea atau tanaman biduri pada bagian kulit batang yang dianggap mampu untuk membasmi nyamuk. Tujuan penelitian ini adalah untuk mengetahui pengaruh dosis ekstrak kulit batang daun biduri terhadap kematian jentik nyamuk. Populasi dalam penelitian ini adalah jentik nyamuk Aedes aegypti dengan total 450 jentik nyamuk dan tanaman biduri bagian kulit batang. Penelitian dilakukan di laboratorium Farmasi UMI yang merupakan penelitian eksperimental. Hasil penelitian menunjukkan bahwa tidak ada pengaruh kematian jentik nyamuk terhadap kematian jentik nyamuk. Pada dosis 0.1 ml ekstrak kulit batang tanaman biduri dalam 100 ml air habitat rata-rata waktu kematian adalah 17.4 menit, dosis 0.5 ml dengan rata-rata waktu 45 menit, dosis 1.0 ml dengan rat-rata waktu kematian 13.2 menit., dosis 1.0 ml dengan rata-rata waktu kematian 30 menit, kemudian pada dosis 2.0ml dengan rata-rata waktu kematian 29.4 menit. Berdasarkan hasil analisis data menunjukkan bahwa nilai p=0.63 &gt; α=0.05. Maka Ha ditolak artinya hipotesis yang menyatakan ada pengaruh dosis ekstrak terhadap kematian jentik nyamuk ditolak. Kesimpulan bahwa tidak ada pengaruh ekstrak kulit batang tanaman biduri terhadap kematian jentik nyamuk. Disarankan agar menggunakan jumlah dosis yang tepat dalam mempengaruhi jentik nyamuk aedes aegypti.

Fumigant Toxicity of Siamese Citrus Fruit Extract (Citrus nobilis) as a Botanical Pesticide in Culex sp.

Toxicity is the ability of a substance that is destructive when exposed to organisms. These substances can come from plants to used as plant-based pesticides. Siam orange peel waste (Citrus nobilis) can be used as the main ingredient of botanical pesticides because it contains bioactive compounds. The purpose of this research is to see the ability of the concentration of siam citrus fruit extracts that can cause mosquito death by 50%. This type of research is experimental and a quantitative approach. The experimental design used a Factorial Complete Randomized Design consisting of seven different treatments and three observation times. These treatments were the concentration of 0% conjoined orange peel extract as a negative control, 30%, 45%, 60%, 75%, 90%, and commercial products as a positive control, the treatment was carried out in four replications. Data were analyzed using probit regression analysis. Probit test results obtained that LC 50 value is 49.86%, the concentration that can be used is in the treatment of P3 with a concentration of 60% of Siamese orange peel extract. The conclusion of this research proves that the administration of conjoined orange peel extract can cause Culex mosquito mortality by 50% at a concentration of 60%.

A novel intervention on the inhibiting effects of Catunaregam spinosa induced free radical formation and DNA damage in Aedes aegypti (Diptera: Culicidae): a verdict for new perspectives on microorganism targeted vector control approach

Plant extracts prompting free radical formation causing DNA damage among especially symbiotic microorganisms of Aedes aegypti has not been extensively examined in previous studies. Here, investigated whether: (1) it was possible to reduce the vectorial capacity by eliminating the microbial consortia of Aedes aegypti larvae, (2) the excess formation of free radical could induce damages of genomic DNA and alter the morphological appearance of Aedes aegypti larvae, and (3) which are the probable mechanisms driving the death of mosquitoes that has been treated with phytochemicals. The toxicity of Catunaregam spinosa seed extracts on the microbial community of Aedes aegypti larvae was determined as previously described. The formation of free radicals was confirmed using the ammonium molybdate method. While the GCMS method was used to assess the phytochemical analysis and the DNA lysing potential. The petroleum ether, ethanol, acetone and water extracts of Catunaregam spinosa has exhibited potent toxicity towards Aedes aegypti larvea’s gut bacterial microbiota, including Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumonia, and Proteus mirabilis with strong MIC values ranging from 0.07 mg/ml to 5.9 mg/ml. Plant extract induced free radical formations and oxidative damage to DNA. The presence of the bioactive element squalene justifies the insecticidal proprieties of Catunaregam spinosa extract. This study reflects the probable mechanisms underlying the lethal effect of Catunaregam spinosa extract on Aedes aegypti, and it potential as a novel biological vector control approach.

Vaccination and vector control effect on dengue virus transmission dynamics: Modelling and simulation

Abstract This paper presents a two-strain compartmental dengue model with variable humans and mosquitoes populations sizes. The model incorporates two control measures: Dengvaxia vaccine and insecticide (adulticide) to forecast the transmission and effective control strategy for dengue in Madeira Island if there is a new outbreak with a different virus serotype after the first outbreak in 2012. The basic reproduction number, R 0 = max { R 01 , R 0 j } , associated with the model is computed using the next generation matrix operator. The disease-free equilibrium is found to be locally asymptotically stable when both R 01 , R 0 j 1 , but unstable otherwise. The global asymptotic stability of the model is derived using the comparison theorem. Sensitivity analysis is carried out on the model parameters. The results of the analysis show that mosquito biting and death rates are the most sensitive parameters. Three strategies: the use of Dengvaxia vaccine only, the use of adulticide only, and the combination of Dengvaxia vaccine and adulticide, are considered for the control implementation under two scenarios (less and more aggressive cases). The numerical results show that a strategy which is based on Dengvaxia vaccine and adulticide is the most effective strategy for controlling dengue disease transmission in both scenarios among the considered strategies.

Modelling for the Reduction and Spread Transmission of the Dynamics and Control of Zika virus Disease: Using Ordinary Differential Equations

The Zika virus is a flavivirus which upon infection in humans causes an illness known as Zika fever. It is commonly identified by popular rash, mild fever and arthritis. The Zika virus (ZIKV) was first identified and isolated from the Zika forest in Uganda in 1947. This paper focuses on human recovery from treatment and death of mosquitoes from insecticides in order to reduce the spread of the virus. This shows that the ZIKV is endemic in a population when the illness exists and is a threat to a population if there is no control. Therefore, the model formulated is unique for analysis. The result of this study shows that the treatment technique without insecticides has no significant reduction in the infected vectors and hosts. The stability of the disease shows stable with R o > 1. Finally, the best option is to use an insecticide to reduce the spread of the virus on both infected hosts and vectors. Keywords : Zika Virus, Modelling, Transmission, Dynamics and Analysis