RETRACTED ARTICLE: Fractional-order scheme for bovine babesiosis disease and tick populations

Abstract

This article shows epidemic model, earlier suggested in ordinary differential equation philosophy, can be extended to fractional order on a reliable agenda of biological comportment. A set of domains for the model wherein allvariables are limited is established. Furthermore, the stability and existence of steadiness points are studied. We present the evidence that the endemic equilibrium (EE) point is locally asymptotically stable when reproduction number $R_{0} > 1$. This outcome is attained via the linearization statement for fractional differential equations (FDEs). The worldwide asymptotic stability of a disease-free point, when $R_{0} < 1$, is also verified by comparison theory for fractional differential equations. The numeric replications for diverse consequences are carried out, and data attained are in good agreement with theoretical outcomes, displaying a vital perception about the use of the set of fractional coupled differential equations to model babesiosis disease and tick populations.

1 Introduction

Bovine babesiosis (BB) is communicated by the bite of ticks and is the most important disease to attack bovine populations in humid areas. In hot and warm areas there is great financial loss due to bovine death by BB, with decrease of bovine products and by-products. Besides, the environment conditions in those regions favor the survival and reproduction of ticks, so bovines have an enduring interaction with these vectors [1]. What is more, the vertical spread in bovines and ticks is likely to happen when the ovaries of the female ticks are plague-ridden by parasites [1]. The behavior dynamics of syndromes has been considered for a stretched period and is an important issue in the real world. The most important model that can be used to interpret the disease characteristic of epidemics is the susceptible-infected-recovered (SIR) model that was developed by Kermack and McKendrick [2]. Various types of diseases are studied by this type of ordinary differential equation system. Aranda et al. [3] introduced the epidemiological model for bovine babesiosis and tick populations disease. In this work the qualitative dynamics behavior is determined by the reproduction number $R_{0}$. If the threshold parameter $R_{0} < 1$ is proved by the LaSalle-Lyapunov theorem, then the solution converges to the disease free equilibrium (DFE) point. However, if $R_{0} > 1$, the merging is to the EE point by numerical imitations. In recent years, the theory of networks epidemiological model has been introduced in the literature. The purpose of this modification is to have a better understanding and prediction of epidemic patterns and intervention measures. For more details, see [4–6].

Leibniz, one of the originators of ordinary calculus, introduced the concept of fractional calculus in a memo transcribed in 1695. In latest eras, FDEs have become one of the most important topics in mathematics and have received much consideration and growing curiosity due to the options of unfolding nonlinear systems and due to their prospective applications in physics, control theory, and engineering [7–15]. The benefit of FDE systems is that they allow greater degrees of freedom and incorporate the memory effect in the model. Due to this fact, they were introduced in epidemiological modeling systems. In [16], a fractional order for the dynamics of A (H1N1) influenza disease was studied by numerical simulations. Pooseh et al. [17] and Diethelm [18] introduced fractional dengue models. In this article the parameters of equations obtained in the field research do not reproduce well the evolution of the disease in the case of entire order model. However, when we consider the fractional system with the same parameters obtained in the field, the data are better adjusted, which shows an advantage of the fractional system. In [11] the parameter θ is associated with a memory effect. In [19], the authors attribute to θ the memory information of the dengue diseases. In this article, we ponder on the fractional order system linked with the development of BB disease and tick populations. We introduce a broad view of the classical model presented by Aranda et al. [3]. The generalization is attained by changing the ordinary derivative with the fractional Caputo derivative. It is easy to see that when $\theta=1$ we return to the classical model. For the construction of this model by Aranda et al. [3], the compartments of populations and the biological hypothesis are used. This argument is well established in the disease transmission theory. Aranda et al. use theorems well established in the literature for ordinary differential systems. To prove our results, it is necessary to use tools different from those used for the integer order. This is due to the fact that the versions of La-Salle invariance theorem used by Aranda et al. are not found in the literature for fractional-order systems. Therefore, we emphasize that the work presents collaboration in this direction when using the comparison theory for fractional-order systems to verify the worldwide stability of DFE point of the disease by introducing a new type of results in the literature. On the other hand, we also have a test on the native asymptotic stability of EE point, a result that was just enunciated by Aranda et al. [3]. We obtain a generalization of all results in [3]. Our simulation shows that the fractional model has great potential to describe the real problem without the need for adjustment of parameters obtained in the field research. This is due to a greater flexibility of adjustment obtained with the introduction of the new parameter.

Fractional calculus represents a generalization of the ordinary differentiation and integration to non-integer and complex order [20]. The generalization of differential calculus to non-integer orders of derivatives can be traced back to Leibnitz [21]. The main reason for using integer order models was the absence of solution methods for fractional differential equations. It is an emerging field in the area of applied mathematics and mathematical physics such as chemistry, biology, economics, image, and signal processing, and it has many applications in many areas of science and engineering [22], for example, viscoelasticity, control theory, heat conduction, electricity, chaos and fractals, etc. [20]. Various applications, like in the reaction kinetics of proteins, the anomalous electron transport in amorphous materials, the dielectrical or mechanical relation of polymers, the modeling of glass forming liquids and others, are successfully performed in numerous papers [21].

The physical and geometrical meaning of the non-integer integral containing the real and complex conjugate power-law exponent has been proposed. Finding examples of real systems described by the fractional derivative is an open issue in the area of fractional calculus [20]. Since integer order differential equations cannot precisely describe the experimental and field measurement data, as an alternative approach, non-integer order differential equation models are now being widely applied [23, 24]. The advantage of fractional-order differential equation systems over ordinary differential equation systems is that they allow greater degrees of freedom and incorporate memory effect in the model. In other words, they provide an excellent tool for the description of memory and hereditary properties which were not taken into account in the classical integer order model [25]. The calculus of variations is widely applied for some disciplines like engineering, pure and applied mathematics. Moreover, the researchers have recently proved that the physical systems with dissipation can be clearly modeled more accurately by using fractional representations [22]. Recently, most of the dynamical systems based on the integer order calculus have been modified into the fractional order domain due to the extra degree of freedom and the flexibility which can be used to precisely fit the experimental data much better than in the case of the integer order modelling.

Purohit and Kalla [26] discussed the generalized fractional partial differential equations involving the Caputo time-fractional derivative and the Liouville space-fractional derivatives. The solutions of these equations are obtained using Laplace and Fourier transforms. Also Purohit [27] discussed the generalized fractional partial differential involving the Hilfer time-fractional derivative and the space-fractional generalized Laplace operators occurring in quantum mechanics. Chouhan et al. [28] presented the method for deriving the solution of the generalized forms of fractional differential equation and Volterra-type differential equation. Nisar et al. [29] discussed a generalized fractional kinetic equation involving generalized Bessel function of the first kind. Also some of interesting nonlinear models and fractional models have been discussed in [30–33].

This article is organized in four segments. Introduction is the first segment in which we elaborate on some history of fractional calculus. In Section 2, we elaborate notations related to the concept of FDEs. In Section 3, we ponder on the fractional-order model linked with the dynamics of bovine babesiosis and tick populations. Qualitative dynamics of the model are resoluted by the elementary reproduction number. We provide a comprehensive investigation for the global asymptotical stability of DFE point and the native asymptotical stability of EE point. In Section 4, numerical imitations are offered to validate the main outcomes, and finally conclusion is drawn in Section 5.

2 Preliminaries

For several ages, there have been numerous definitions that fit the notion of fractional derivatives [10, 34]. In this article the Riemann-Liouville fractional derivative, the Caputo fractional derivative, and Grunwald-Letnikov definitions are presented. Firstly, we introduce the definition of Riemann-Liouville fractional integral

$$ J^{\varphi} g ( x ) = \frac{1}{\Gamma (\varphi)} \int_{0}^{x} (x-s)^{\varphi-1} g ( s ) \,ds, $$

(1)

where $\varphi>0$, $f\in L^{1} ( R^{+} )$, and $\Gamma (\cdot)$ is gamma function.

The Riemann-Liouville derivative is given by

$$ D_{R}^{\varphi} g ( x ) = \frac{d^{m}}{d x^{m}} \bigl[ J^{m-\varphi} g ( x ) \bigr] = \frac{1}{\Gamma (m-\varphi)} \frac{d^{m}}{d x^{m}} \int_{0}^{x} (x-s)^{m-\varphi-1} g ( s ) \,ds,\quad m-1\leq \varphi< m. $$

(2)

The Caputo fractional derivative (CFD) is agreed to be as follows:

$$ D_{C}^{\varphi} g ( x ) = J^{m-\varphi} \biggl[ \frac{d^{m}}{d x^{m}} g ( x ) \biggr] = \frac{1}{\Gamma (m-\varphi)} \int_{0}^{x} (x-s)^{m-\varphi-1} g^{(m)} ( s ) \,ds, $$

(3)

where m is the first integer not less than φ.

The Grunwald-Letnikov derivative is given by

$$ {}_{a} D_{x_{k}}^{\varphi} g ( x ) = \lim _{h\rightarrow0} \frac{1}{h^{\varphi}} \sum_{j=0}^{[ \frac{x-a}{h} ]} (-1 )^{j} \biggl( \frac{\varphi}{j} \biggr) g ( x-jh ), $$

(4)

where $[\cdot]$ means the integer part.

The Laplace transform of the CFD is specified by

$$ \mathcal{L} \bigl[ D_{C}^{\varphi} g ( x ) \bigr] = s^{\varphi} G ( s ) - \sum_{j=0}^{n-1} g^{ ( j )} ( 0 ) s^{\varphi-j-1}. $$

(5)

The Mittag-Leffler function is defined by the following infinite power series:

$$ E_{\alpha,\beta} ( z ) = \sum_{k=0}^{\infty} \frac{z^{k}}{ (\alpha k+\beta)}. $$

(6)

The Laplace transform of the functions is

$$ \mathcal{L} \bigl[ t^{\beta-1} E_{\alpha,\beta} \bigl( \pm a t^{\alpha} \bigr) \bigr] = \frac{s^{\alpha-\beta}}{s^{\alpha} \mp a}. $$

(7)

Let $\alpha, \beta > 0$, and $z \in \mathbb{C}$, and the Mittag-Leffler functions satisfy the equality given by Theorem 4.2 in [10]

$$ E_{\alpha,\beta} ( z ) =z E_{\alpha,\alpha+\beta} ( z ) + \frac{1}{\Gamma (\beta)}. $$

(8)

Demarcation 1

A function F is Holder continuous if there are non-negative amounts G, ν such that

$$ \bigl\Vert F ( u ) -F(v) \bigr\Vert \leq G \Vert u-v \Vert ^{\nu}, $$

(9)

for all u, v in the purview of F and ν is the Holder exponent. We represent the space of Holder-continuous functions by $G^{0,\nu}$.

We improve a generalized inequality, in which the core appraisal system is a vector fractional order system.

A non-negative (resp., positive) vector ν means that each constituent of ν is non-negative (resp., positive). We represent a non-negative (resp., positive) vector by $0 \leq\leq \nu$ (resp., $0 \ll \nu$).

Consider the fractional order system

$$ D_{C}^{\varphi} w ( t ) =g(t,w), $$

(10)

with the initial condition $w ( 0 ) = w_{0}$, where $D_{C}^{\varphi} w ( t ) =( D_{C}^{\varphi} w_{1} ( t ), D_{C}^{\varphi} w_{2} ( t ), D_{C}^{\varphi} w_{3} ( t ),\dots, D_{C}^{\varphi} w_{m} ( t ) )^{H}$, $0< \varphi<1$, $w ( t ) \in \mathcal{F}\subset R^{m}$, $t\in [ 0,H )$ ($H\leq\infty$), $\mathcal{F}$ is an open set, $0\in \mathcal{F}$, and $g: [ 0,H ) \times \mathcal{ F}\rightarrow R^{m}$ is continuous in t and mollifies the Lipschitz condition

$$ \bigl\Vert g \bigl( t,w' \bigr) -g \bigl(t,w'' \bigr) \bigr\Vert \leq W \bigl\Vert w'-w'' \bigr\Vert ,\quad t\in [ 0,H ) $$

(11)

for all $w ',w''\in \Omega \subset \mathcal{F}$, where $W>0$ is a Lipschitz constant.

Theorem 1

see [15]

Let $u(t)$, $t \in [ 0, H)$, be the solution of system (10). If there exists a vector function $w = ( w_{1}, w_{2}, \dots, w_{m} )^{H}: [ 0,H ) \rightarrow \mathcal{F}$ such that $w_{i} \in G^{0,\nu}$, $\varphi< w<1$, $i=1,2,\dots, m$, and

$$ D_{C}^{\varphi} w \leq\leq g(t, w ),\quad t\in [ 0,H ]. $$

(12)

If $w(0)\leq\leq u_{0}$, $u_{0} \mathcal{\in F}$, then $w\leq\leq u$, $t\in [ 0,H ]$.

Let $g \mathcal{:F\rightarrow} R^{m}$, $\mathcal{F\in} R^{m}$, we consider the following system of fractional order:

$$ D_{C}^{\varphi} x ( t ) =g(x),\quad x ( 0 ) = x_{0}. $$

(13)

Demarcation 2

We say that E is an equilibrium point of (13) if and only if $g ( E ) =0$.

Remark 1

When $\varphi \in ( 0, 1 )$, the fractional system $D_{C}^{\varphi} x ( t ) =g(x)$ has identical equilibrium points as the arrangement $x ' ( t ) =g(x)$.

Definition 3

The equilibrium point E of autonomous system (13) is said to be stable if for all $\epsilon>0$, $\varepsilon>0$ exists such that if $\Vert x_{0} -E \Vert <\varepsilon$, then $\Vert x-E \Vert <\epsilon$, $t \geq0$; the equilibrium point E of autonomous system (13) is said to be asymptotically unwavering if $\lim_{t\rightarrow\infty} x(t) =E$.

Theorem 2

[12]

The equilibrium points of system (13) are locally asymptotically stable if all eigenvalues $\lambda_{\mathrm{i}}$ of the Jacobian matrix J, calculated in the equilibrium points, satisfy $\vert \arg ( \lambda_{\mathrm{i}} ) \vert > \varphi \frac{\pi}{2}$.

3 Mathematical model

In this segment, we introduce the fractional model for the BB in bovine and tick populations. We use the assumptions in Aranda et al. [3] and introduce the following hypotheses.

• (i) The total of bovine population $T_{B} (t)$ is distributed into three-fold sub-populations:

  • (a) the susceptible $X_{B} (t)$ that can turn into infected;

  • (b) the infected $Y_{B} (t)$, that is, bovines infected by Babesia parasite;

  • (c) the recovered or controlled $Z_{B} (t)$ that have been cured.

• (ii) The birth rate factor of bovine is represented by $\mu_{B}$. The birth rate μ is presumed to be equal to the normal demise.

• (iii) $T_{T} (t)$ is the entire population of ticks that is distributed into two-fold sub-populations:

  • (a) $X_{T} (t)$ is tick population which may become infected by the disease;

  • (b) ticks infected by Babesia parasite are represented by $Y_{T} (t)$.

• (iv) The birth rate factor of ticks is represented by $\mu_{T}$, and it is presumed to be equal to the normal demise rate.

• (v) A susceptible bovine can move to the infected sub-population $Y_{B} (t)$ as of an effective transmission due to a sting of an infected tick at rate $\beta_{B}$.

• (vi) A susceptible tick may be infected if there exists an active diffusion when it bites a diseased bovine at rate $\beta_{T}$.

• (vii) We presumed a hundred percent vertical diffusion in the bovine population $\mu_{B}$. In the tick population it befalls with possibility $1-p$, where p is the possibility that a susceptible tick was born from an infected one.

• (viii) A fraction $\lambda_{B}$ of the diseased bovine is controlled, i.e., free from Babesia parasite.

• (ix) A fraction α of the controlled bovine can yield to the susceptible state, $\alpha\in ( 0, 1 )$.

• (x) Identical involvement is presumed, i.e., all susceptible bovines have equal possibility to the diseased, and all susceptible ticks have equal possibility to the diseased.

In the above conventions, the transmission dynamics of babesiosis disease to bovine and tick populations can be modeled by the following system [3]:

$$ \textstyle\begin{cases} X '_{B} = \mu_{B} ( X_{B} + Z_{B} ) +\alpha Z_{B} - \mu_{B} X_{B} - \beta_{B} X_{B} \frac{Y_{T}}{T_{T}},\\ Y '_{B} = \mu_{B} Y_{B} + \beta_{B} X_{B} \frac{Y_{T}}{T_{T}} -( \mu_{B} + \lambda_{B} ) Y_{B},\\ Z '_{B} = \lambda_{B} Y_{B} -( \mu_{B} + \alpha ) Z_{B},\\ X '_{T} = \mu_{T} ( X_{T} +p Y_{T} ) - \mu_{T} X_{T} - \beta_{T} X_{T} \frac{Y_{B}}{T_{B}},\\ Y '_{T} =- \mu_{T} Y_{T} + \beta_{T} X_{T} \frac{Y_{B}}{T_{B}} +(1-p) Y_{B}. \end{cases} $$

(14)

3.1 Fractional order model

In current years, a substantial attention to the fractional calculus has been shown, which allows us to consider integration and differentiation of any order. To a large extent, this is due to the uses of fractional calculus to problems in different areas of research. The benefit of FDE systems is that they allow greater degrees of freedom and incorporate memory effect in the model. Now we describe a new system of FDEs to model the babesiosis disease in bovine and tick populations, and in this system $\phi \in ( 0, 1 )$.

$$ \textstyle\begin{cases} D^{\phi_{1}} X_{B} = \mu_{B} ( X_{B} + Z_{B} ) +\alpha Z_{B} - \mu_{B} X_{B} - \beta_{B} X_{B} \frac{Y_{T}}{T_{T}},\\ D^{\phi_{2}} Y_{B} = \mu_{B} Y_{B} + \beta_{B} X_{B} \frac{Y_{T}}{T_{T}} -( \mu_{B} + \lambda_{B} ) Y_{B},\\ D^{\phi_{3}} Z_{B} = \lambda_{B} Y_{B} -( \mu_{B} + \alpha ) Z_{B},\\ D^{\phi_{4}} X_{T} = \mu_{T} ( X_{T} +p Y_{T} ) - \mu_{T} X_{T} - \beta_{T} X_{T} \frac{Y_{B}}{T_{B}},\\ D^{\phi_{5}} Y_{T} =- \mu_{T} Y_{T} + \beta_{T} X_{T} \frac{Y_{B}}{T_{B}} +(1-p) Y_{B}. \end{cases} $$

(15)

Simplifying system (15), using the bovine and tick populations’ constants $T_{B}$ and $T_{T}$, respectively, and introducing the proportions

$$ U = \frac{X_{B}}{T_{B}},\qquad V = \frac{Y_{B}}{T_{B}},\qquad W = \frac{Z_{B}}{T_{B}},\qquad X = \frac{X_{T}}{T_{T}},\qquad Z = \frac{X_{T}}{T_{T}}, $$

(16)

we attain the following fractional system that defines the dynamics of bovine quantity in each class:

$$ \textstyle\begin{cases} D^{\phi_{1}} U= ( \mu_{B} + \alpha ) ( 1-U-V ) - \beta_{B} UZ,\\ D^{\phi_{2}} V= \beta_{B} UZ- \lambda_{B} V,\\ D^{\phi_{3}} Z= \beta_{T} ( 1-Z ) V- \mu_{T} p Z. \end{cases} $$

(17)

Defined in the region $\Omega = \{ ( U,V,Z ):0\leq U+V\leq1, 0\leq Z\leq1 \}$, the system is called commensurate if $\phi=\phi_{1} = \phi_{2} = \phi_{3}$; otherwise it is called incommensurate. The chaotic behavior of the system, when the total order of system is less than three, is an interesting topic, and it is connected to the fractal phase space in dynamics. Next we show all variables of the babesiosis model living in Ω for all time $t\geq0$. To establish our first result, we introduce the following lemma.

Lemma 1

see [35]

Let the function $f\in C[ t_{0}, t_{1} ]$ and its fractional derivative $D_{C}^{\varphi} f ( t ) \in C[ t_{0}, t_{1} ]$ for $0\leq \varphi<1$, and $t_{0}, t_{1} \mathbb{\in R}$; then one has

$$ f ( t ) =f ( t_{0} ) + \frac{1}{\Gamma ( \varphi )} D_{C}^{\varphi} f ( \tau ) (t- t_{0} )^{\varphi} $$

(18)

for all $t\in( t_{0}, t_{1}]$, where $t_{0} \leq\tau< t$.

Therefore, considering the interval $[0, t_{1} ]$ for any $t_{1} >0$, this theorem infers that the function $f: [0,t_{1} ]\rightarrow \mathbb{R}^{+}$ is non-increasing on $(0, t_{1})$ if $D_{C}^{\varphi} f ( t ) \leq0$ for all $t\in( 0,t_{0} )$ and non-decreasing on $[ 0,t_{0} ]$ if $D_{C}^{\varphi} f ( t ) \geq0$ for all $t\in( 0,t_{0} )$.

Preposition 1

The region $\Omega = \{ ( U,V,Z ):0\leq U+V\leq1, 0\leq Z\leq1 \}$ is a positive invariant set for system of (17).

Proof

By Theorem 3.1 and Remark 3.2 in [36], we obtain the global presence and rareness of the elucidations of (17).

We denote $\Omega_{+} = \{ ( U,V,Z ):U\geq0,V\geq0,Z\geq0 \}$ if $( U(0),V(0),Z(0) ) \in U\text{-axis}=\{ ( U,0,0 ):U\geq0\}$. Similarly, we can define V-axis and Z-axis. The vector field from (17) confined in U-axis assumes the form $F ( U,V,Z ) =( ( \mu_{B} + \alpha ) ( 1-U ( t ) ), 0,0)$ by the Laplace transform properties (7), and we obtain the elucidation

$$ \begin{aligned}[b] &( U,V,Z ) \\ &\quad = \bigl( t^{\varphi} E_{\varphi,\varphi+1} \bigl( - ( \mu_{B} + \alpha ) t^{\varphi} \bigr) ( \mu_{B} + \alpha ) + E_{\varphi,1} \bigl( - ( \mu_{B} + \alpha ) t^{\varphi} \bigr) U(0),0,0 \bigr)\in U\text{-axis}. \end{aligned} $$

(19)

By the same argument, if $( U(0),V(0),Z(0) ) \in V$-axis, we obtain

$$ ( U,V,Z ) = \bigl(0, E_{\varphi,1} \bigl(- \lambda_{B} t^{\varphi} \bigr)V(0),0 \bigr)\in V\text{-axis}, $$

(20)

and if $( U(0),V(0),Z(0) ) \in Z$-axis, we have

$$ ( U,V,Z ) = \bigl(0,0, E_{\varphi,1} \bigl(- \mu_{T} p t^{\varphi} \bigr)V(0) \bigr)\in V\text{-axis}. $$

(21)

This proves that axes U, V, and Z are solutions and positive invariant sets.

Now, we will prove that $\Omega_{+}$ is a positive invariant set. By way of contradiction, suppose there exists a solution $( U,V,Z )$ such that $( U ( 0 ),V ( 0 ),Z ( 0 ) ) \in \Omega_{+}$ and the solution $( U,V,Z )$ to escape of $\Omega_{+}$. From the previous argument and by the unicity of solutions, $( U,V,Z )$ does not cross the axis. After the previous conclusion, there are three possibilities.

• (i) If the solution $( U,V,Z )$ escapes by the plane $U ( t ) =0$, then there exists $t_{0}$ such that $U ( t_{0} ) =0$, $V ( t_{0} ) >0$, and $Z ( t_{0} ) >0$; and for all $t> t_{0}$ sufficiently near $t_{0,}$ we have $U ( t_{0} ) <0$. Alternatively, $D_{C}^{\varphi} U ( t ) | _{t= t_{0}} = ( \mu_{B} + \alpha ) ( 1-V ( t_{0} ) ) > ( \mu_{B} + \alpha ) >0$. From Lemma 1, we obtain $U \geq U ( t_{0} ) \geq0$ for all t sufficiently near $t_{0}$, and it is not true.

• (ii) If the solution $( U,V,Z )$ escapes by the plane $V ( t ) =0$, then there exists $t_{0}$ such that $U ( t_{0} ) >0$, $V ( t_{0} ) =0$, and $Z ( t_{0} ) >0$; and for all $t> t_{0}$ sufficiently near $t_{0,}$we have $V ( t_{0} ) <0$. Alternatively, $D_{C}^{\varphi} V ( t ) | _{t= t_{0}} = \beta_{B} U( t_{0} ) Z ( t_{0} ) >0$. From Lemma 1, we obtain $V ( t ) \geq V ( t_{0} ) \geq0$ for all t sufficiently near $t_{0}$, and it is not true.

• (iii) If the solution $( U,V,Z )$ escapes by the plane $Z ( t ) =0$, then there exists $t_{0}$ such that $U ( t_{0} ) >0$, $V ( t_{0} ) >0$, and $Z ( t_{0} ) =0$; and for all $t> t_{0}$ sufficiently near $t_{0,}$we have $Z ( t_{0} ) <0$. On the other hand, $D_{C}^{\varphi} Z ( t ) | _{t= t_{0}} = \beta_{T} V( t_{0} )>0$. From Lemma 1, we obtain $Z\geq Z ( t_{0} ) \geq0$ for all t sufficiently near $t_{0}$, and it is false.

Therefore, we obtain $U\geq0$, $V\geq0$, and $Z\geq0$ for all $t\geq0$.

If $0\leq U ( 0 ) +V(0)\leq1$, from the first two equations of system (17), we get

$$ \begin{aligned}[b] D_{C}^{\varphi} \bigl( U ( t ) +V ( t ) \bigr) &= ( \mu_{B} + \alpha ) - ( \mu_{B} + \alpha ) \bigl( U ( t ) +V ( t ) \bigr) - \lambda_{B} V(t) \\ &\leq ( \mu_{B} + \alpha ) - ( \mu_{B} + \alpha ) \bigl( U ( t ) +V ( t ) \bigr). \end{aligned} $$

(22)

Applying the Laplace transform in the previous inequality, we have

$$ \begin{aligned}[b] &\lambda^{\varphi} \mathcal{ L} \bigl( U ( t ) +V ( t ) \bigr) - \lambda^{\varphi-1} \bigl( U ( 0 ) +V ( 0 ) \bigr) \\ &\quad \leq \lambda^{-1} ( \mu_{B} + \alpha ) - ( \mu_{B} + \alpha ) \mathcal{L} \bigl( U ( t ) +V ( t ) \bigr). \end{aligned} $$

(23)

That can be written as

$$ \mathcal{L} \bigl( U ( t ) +V ( t ) \bigr) \leq ( \mu_{B} + \alpha ) \frac{\lambda^{\varphi- ( 1+\varphi )}}{\lambda^{\varphi} + \mu_{B} + \alpha} + \frac{\lambda^{\varphi-1}}{\lambda^{\varphi} + \mu_{B} + \alpha} \bigl( U ( 0 ) +V ( 0 ) \bigr). $$

(24)

From the Laplace transform properties (7) and (8), we infer that

$$\begin{aligned} \bigl(U ( t ) +V ( t ) \bigr) \leq& t^{\varphi} E_{\varphi,\varphi+1} \bigl( - ( \mu_{B} + \alpha ) t^{\varphi} \bigr) ( \mu_{B} + \alpha ) + E_{\varphi,1} \bigl( - ( \mu_{B} + \alpha ) t^{\varphi} \bigr) \bigl(U ( 0 ) +V ( 0 ) \bigr) \\ \leq& t^{\varphi} E_{\varphi,\varphi+1} \bigl( - ( \mu_{B} + \alpha ) t^{\varphi} \bigr) ( \mu_{B} + \alpha ) + E_{\varphi,1} \bigl( - ( \mu_{B} + \alpha ) t^{\varphi} \bigr) =1. \end{aligned}$$

(25)

Therefore, we have that $0\leq U ( t ) +V ( t ) \leq1$.

On the other hand, if $0\leq Z ( t ) \leq1$, from system (17) we obtain

$$ \begin{aligned} D_{C}^{\varphi} ( Z ) &= \beta_{T} ( 1-Z ) V- \mu_{T} p Z \\ &\leq (\beta_{T} + \mu_{T} p) ( 1-Z ). \end{aligned} $$

(26)

The proof of $0\leq Z ( t ) \leq1$ is similar to the previous case. Finally, we conclude that Ω is a positive invariant set. □

3.2 Existence and stability of equilibrium points

There are two equilibrium points of system (17). Motivated by Aranda et al. [3], we will use the following threshold parameter. For more details on the threshold parameter, see [37, 38].

$$ R_{0} = \frac{\beta_{B} \beta_{T}}{\lambda_{B} \mu_{T} p}. $$

(27)

The value that $R_{0}$ yields can specify the situations in which the epidemic is likely. In the drug using context, $R_{0}$ tells us, on average, the total number of people that each single drug user will initiate to drug use through the drug using career.

3.3 $R_{0}$ sensitivity analysis

To examine the sensitivity of $R_{0}$ to each of its factors,

$$\begin{aligned}& \frac{\partial R_{0}}{\partial \beta_{B}} = \frac{\beta_{T}}{\lambda_{B} \mu_{T} p} >0, \\& \frac{\partial R_{0}}{\partial \beta_{T}} = \frac{\beta_{B}}{\lambda_{B} \mu_{T} p} >0, \\& \frac{\partial R_{0}}{\partial \lambda_{B}} =- \frac{\beta_{B} \beta_{T}}{ ( \lambda_{B} )^{2} \mu_{T} p} < 0, \\& \frac{\partial R_{0}}{\partial \mu_{T}} =- \frac{\beta_{B} \beta_{T}}{ \lambda_{B} ( \mu_{T} )^{2} p} < 0, \\& \frac{\partial R_{0}}{\partial p} =- \frac{\beta_{B} \beta_{T}}{ \lambda_{B} \mu_{T} ( p )^{2}} < 0. \end{aligned}$$

Thus $R_{0}$ is increasing with $\beta_{B}$ & $\beta_{T}$ and is decreasing with $\lambda_{B}$, $\mu_{T}$ & p.

3.4 Stability of DFE

System (17) has the DFE, i.e., $E_{0} =(1,0,0)$, for all the values of the factors in this system, whereas only if $R_{0} >1$, there is a (unique) EE point, i.e., $E_{1} =( U^{*}, V^{*}, Z^{*} )$, where

$$ \begin{gathered} U^{*} = \frac{\lambda_{B} \{ ( \mu_{B} + \alpha ) \beta_{T} +p \mu_{T} ( \mu_{B} + \alpha+ \lambda_{B} )\}}{\beta_{T} \{ \alpha ( \beta_{B} + \lambda_{B} ) + \mu_{B} \lambda_{B} + \beta_{B} ( \mu_{B} + \lambda_{B} )\}}, \\ V^{*} = \frac{( \mu_{B} + \alpha )( \beta_{B} \beta_{T} - \lambda_{B} \mu_{T} p)}{\beta_{T} \{ \alpha ( \beta_{B} + \lambda_{B} ) + \mu_{B} \lambda_{B} + \beta_{B} ( \mu_{B} + \lambda_{B} )\}}, \\ Z^{*} = \frac{( \mu_{B} + \alpha )( \beta_{B} \beta_{T} - \lambda_{B} \mu_{T} p)}{ ( \mu_{B} + \alpha ) \beta_{B} \beta_{T} + ( \mu_{B} + \alpha+ \lambda_{B} ) \beta_{B} \mu_{T} p} \end{gathered} $$

(28)

in the interior of Ω.

The Jacobian matrix of system (17) is

$$ J= \left [ \textstyle\begin{array}{c@{\quad}c@{\quad}c} - ( \mu_{B} + \alpha ) - \beta_{B} Z(t) & - ( \mu_{B} + \alpha ) & - \beta_{B} U(t) \\ \beta_{B} Z(t) & - \lambda_{B} & \beta_{B} U(t) \\ 0 & \beta_{T} (1-Z(t)) & - \beta_{T} V(t)- \mu_{T} p \end{array}\displaystyle \right ]. $$

(29)

Now the Jacobian of system (17) at the DFE $(1,0,0)$ is

$$J( E_{0} )= \left [ \textstyle\begin{array}{c@{\quad}c@{\quad}c} - ( \mu_{B} + \alpha ) & - ( \mu_{B} + \alpha ) & - \beta_{B} \\ 0 & - \lambda_{B} & \beta_{B} \\ 0 & \beta_{T} & - \mu_{T} p \end{array}\displaystyle \right ].\hspace{147.5pt}\mathrm{ \bigl(29^{*}\bigr)} $$

Consequently, the eigenvalues of $J( E_{0} )$ are

$$ \begin{gathered} \lambda_{1} =- ( \mu_{B} + \alpha ), \\ \lambda_{2} = \frac{- ( \lambda_{B} + \mu_{T} p ) + \sqrt{ ( \lambda_{B} - \mu_{T} p )^{2} +4 \beta_{B} \beta_{T}}}{ 2}, \\ \lambda_{3} = \frac{- ( \lambda_{B} + \mu_{T} p ) - \sqrt{ ( \lambda_{B} - \mu_{T} p )^{2} +4 \beta_{B} \beta_{T}}}{2}. \end{gathered} $$

(30)

It is easy to see that $\lambda_{2}$ and $\lambda_{3}$ are negative numbers. If $R_{0} <1$, we observe

$$\begin{aligned} ( \lambda_{B} - \mu_{T} p )^{2} +4 \beta_{B} \beta_{T} &= \lambda_{B}^{2} + \mu_{T}^{2} p^{2} -2 \lambda_{B} \mu_{T} p +4 \beta_{B} \beta_{T} \\ &< \lambda_{B}^{2} + \mu_{T}^{2} p^{2} +2 \lambda_{B} \mu_{T} p= ( \lambda_{B} + \mu_{T} p )^{2}. \end{aligned}$$

So,

$$\begin{aligned} \lambda_{2} &= \frac{- ( \lambda_{B} + \mu_{T} p ) + \sqrt{ ( \lambda_{B} - \mu_{T} p )^{2} +4 \beta_{B} \beta_{T}}}{2} \\ &< \frac{- ( \lambda_{B} + \mu_{T} p ) + \sqrt{ ( \lambda_{B} + \mu_{T} p )^{2}}}{2} =0 \end{aligned}$$

and

$$\begin{aligned} \lambda_{3} &= \frac{- ( \lambda_{B} + \mu_{T} p ) - \sqrt{ ( \lambda_{B} - \mu_{T} p )^{2} +4 \beta_{B} \beta_{T}}}{2} \\ &< \frac{- ( \lambda_{B} + \mu_{T} p ) - \sqrt{ ( \lambda_{B} + \mu_{T} p )^{2}}}{2} =- ( \lambda_{B} + \mu_{T} p ) < 0. \end{aligned}$$

Therefore $\lambda_{2} <0$ and $\lambda_{3} <0$; then we have that all the eigenvalues of the Jacobian matrix at $E_{0}$ are negative, i.e., $\vert \arg ( \lambda_{i} ) \vert =\pi$, $i=1,2,3$, and from Theorem 2, we have that the DFE point $E_{0}$ is locally asymptotically stable. Consequently, we have the following theorem.

Theorem 3

If $R_{0} <1$, then the disease-free point $E_{0}$ is locally asymptotically stable.

Now we will prove the global asymptotic stability of the DFE point.

Theorem 4

If $R_{0} <1$, then the disease-free point $E_{0}$ is worldwide asymptotically stable.

Proof

Suppose that $( U,V,Z )$ is the elucidation of system (17). Creating the variation of variables $M=1-U$, we obtain the new system

$$ \textstyle\begin{cases} D^{\phi_{1}} M=- ( \mu_{B} + \alpha ) M+ ( \mu_{B} + \alpha ) V+ \beta_{B} Z- \beta_{B} M Z,\\ D^{\phi} V= \beta_{B} (1-M)Z- \lambda_{B} V,\\ D^{\phi_{3}} Z= \beta_{T} ( 1-Z ) V- \mu_{T} p Z. \end{cases} $$

(31)

It is easy to see that

$$ \begin{gathered} - ( \mu_{B} + \alpha ) (M-V)+ \beta_{B} (1-M)Z \leq - ( \mu_{B} + \alpha ) (M-V)+ \beta_{B} Z, \\ \beta_{B} (1-M)Z- \lambda_{B} V \leq \beta_{B} Z- \lambda_{B} V, \\ \beta_{T} ( 1-Z ) V- \mu_{T} p Z \leq \beta_{T} V- \mu_{T} p Z. \end{gathered} $$

(32)

From the above, it follows that the solutions $( M,V, Z )$ of system (31) satisfy the differential inequality

$$ \textstyle\begin{cases} D^{\phi_{1}} M \leq - ( \mu_{B} + \alpha ) ( M-V ) + \beta_{B} Z, \\ D^{\phi_{2}} V \leq \beta_{B} Z- \lambda_{B} V, \\ D^{\phi_{3}} Z \leq \beta_{T} V- \mu_{T} p Z. \end{cases} $$

(33)

Moreover, inspired by (33), let $( S,T,W )$ be the solution of the fractional linear system

$$ \textstyle\begin{cases} D^{\phi_{1}} S = - ( \mu_{B} + \alpha ) (S-T)+ \beta_{B} W,\\ D^{\phi_{2}} T = \beta_{B} W- \lambda_{B} T ,\\ D^{\phi_{3}} W = \beta_{T} T- \mu_{T} p W \end{cases} $$

(34)

with ICs $( S ( 0 ),T ( 0 ),W ( 0 ) ) \in\Omega$. The Jacobian of system (34) is

$$ J= \left [ \textstyle\begin{array}{c@{\quad}c@{\quad}c} - ( \mu_{B} + \alpha ) & - ( \mu_{B} + \alpha ) & - \beta_{B} \\ 0 & - \lambda_{B} & \beta_{B} \\ 0 & \beta_{T} & - \mu_{T} p \end{array}\displaystyle \right ]. $$

(35)

So the Jacobian at the DFE is

$$J( E_{0} )= \left [ \textstyle\begin{array}{c@{\quad}c@{\quad}c} - ( \mu_{B} + \alpha ) & - ( \mu_{B} + \alpha ) & - \beta_{B} \\ 0 & - \lambda_{B} & \beta_{B} \\ 0 & \beta_{T} & - \mu_{T} p \end{array}\displaystyle \right ],\hspace{146.5pt}\mathrm{ \bigl(35^{*}\bigr)} $$

and the eigenvalues of $J( E_{0} )$ are the same as derived above. Here we have proved that all the eigenvalues are negative. Thus $\vert \arg ( \lambda_{i} ) \vert =\pi$, $i=1,2,3$, and we can conclude that $\lim_{t\rightarrow\infty} S=0$, $\lim_{t\rightarrow\infty} T=0$, $\lim_{t\rightarrow\infty} W=0$. So, by Theorem 1, we have $( M,V, Z ) \leq\leq ( S,T,W )$. This implies that $\lim_{t\rightarrow\infty} ( M,V, Z ) =(0,0,0)$, and it follows that $( U,V, Z )$ converges to the DFE point $E_{0} =(1,0,0)$, when $R_{0} <1$. □

3.5 Stability of EE

Now we will show the local stability of the EE point $E_{1}$ with the help of some definitions [39, 40].

Definition 4

Let Q be any matrix of real and complex numbers with order $n\times m$, let $q_{i_{1},\dots, j_{k}}$be the minor of A determined by the rows $(i_{1},\dots, i_{k})$ and the columns $(j_{1,} \dots, j_{k})$, with $1\leq i_{1} < i_{2} <\cdots< i_{k} \leq n$, and $1\leq j_{1} < j_{2} <\cdots< j_{k} \leq m$. The kth multiplicative compound matrix of $Q^{k}$ of Q is the $( \frac{n}{k} ) \times ( \frac{n}{k} )$ matrix whose entries, written in a lexicographic order, are $q_{i_{1},\dots, j_{k}}$. When Q is an $n\times m$ matrix with columns $q_{1}, q_{2},\dots, q_{k}$, $Q^{k}$ is the exterior product $q_{1} \wedge q_{2} \wedge\cdots\wedge q_{k}$.

Definition 5

Let $Q= q_{ij}$ be an $n\times n$ matrix, its kth additive compound matrix of $Q^{k}$ of Q is the $( \frac{n}{k} ) \times ( \frac{n}{k} )$ matrix given by $Q^{[k]} = \vert D(I+hQ)^{(k)} \vert =0$, where D is a differentiation with respect to h. For any integers $i=1,\dots, ( \frac{n}{k} )$, let $( i ) =( i_{1},\dots, i_{k} )$ be the ith member in the lexicographic ordering of all k-tuples of integers such that $1\leq i_{1} < i_{2} <\cdots< i_{k} \leq i_{n}$, then

$$b_{ij} = \textstyle\begin{cases} q_{i_{1} i_{1}} +\cdots+ q_{i_{k} i_{k}},& \mbox{if } ( i ) = ( j ),\\ (-1)^{r+s} q_{i_{r} i_{s}}, & \mbox{if one entry of }i_{s}\mbox{ of } ( i )\mbox{ does not occur in } ( j )\mbox{ and }j_{s} \\ &\mbox{does not occur in } ( i ),\\ 0, &\mbox{if } ( i )\mbox{ differs from } ( j )\mbox{ in two or more enteries}. \end{cases} $$

Remark 2

For $n=3$, the matrices $Q^{[k]}$ are as follows:

$$ \begin{gathered} Q^{[1]} =Q,\qquad Q^{[2]} = \left [ \textstyle\begin{array}{c@{\quad}c@{\quad}c} q_{11} + q_{22} & q_{23} & -q_{13} \\ q_{32} & q_{22} + q_{33} & q_{12} \\ - q_{31} & q_{21} & q_{22} + q_{33} \end{array}\displaystyle \right ], \\ Q^{[3]} = q_{11} + q_{22} + q_{33}. \end{gathered} $$

(36)

Lemma 2

Let O be a $3\times3$ real matrix. If $\operatorname {tr}( O ) <0$, $\det ( O ) <0$, and $\det ( O^{[2]} ) <0$ are all negative, then all eigenvalues of O have negative real parts.

Theorem 5

If $R_{0} >1$, $( \mu_{B} + \alpha ) > \beta_{T}$, and $( \mu_{B} + \alpha ) > \beta_{B}$, then EE point $E_{1}$ is locally asymptotically stable.

Proof

The Jacobian matrix of system (17) is given in (29).

From (29)

$$\operatorname {tr}\bigl( J( E_{1} ) \bigr) =- ( \mu_{B} + \alpha ) - \beta_{B} Z - \lambda_{B} - \beta_{T} V- \mu_{T} p< 0. $$

To see that $\det ( J( E_{1} ) ) <0$, we proceed as follows.

Since

$$ - ( \mu_{B} + \alpha ) = \frac{- \beta_{B} UZ}{ ( 1-U-V )}, \quad\quad \lambda_{B} = \frac{\beta_{B} UZ}{V}, \quad\quad \mu_{T} p= \frac{\beta_{T} ( 1-Z ) V}{Z}, $$

(37)

substituting (37) in (29), we have

$$\det \bigl( J( E_{1} ) \bigr) = \left \vert \textstyle\begin{array}{c@{\quad}c@{\quad}c} \frac{- \beta_{B} UZ}{ ( 1-U-V )} - \beta_{B} Z & \frac{- \beta_{B} UZ}{ ( 1-U-V )} & - \beta_{B} U \\ \beta_{B} Z & - \frac{\beta_{B} UZ}{V} & \beta_{B} U \\ 0 & \beta_{T} (1-Z) & - \beta_{T} V- \frac{\beta_{T} ( 1-Z ) V}{Z} \end{array}\displaystyle \right \vert . $$

On simplification

$$ \det \bigl( J( E_{1} ) \bigr) = \left \vert \textstyle\begin{array}{c@{\quad}c@{\quad}c} \frac{\beta_{B} Z ( 1-V )}{ ( 1-U-V )} & \frac{- \beta_{B} UZ}{ ( 1-U-V )} & - \beta_{B} U \\ \beta_{B} Z & - \frac{\beta_{B} UZ}{V} & \beta_{B} U \\ 0 & \beta_{T} (1-Z) & - \frac{\beta_{T} V}{Z} \end{array}\displaystyle \right \vert . $$

(38)

We can easily see that $\det ( J( E_{1}) ) <0$, because all the parameters are positive constants.

Now we will show that $\det ( J^{[2]} ( E_{1} ) ) <0$.

For this,

$$\begin{aligned}& \det \bigl( J^{[2]} ( E_{1} ) \bigr) \\& \quad = \left \vert \textstyle\begin{array}{c@{\quad}c@{\quad}c} - ( \mu_{B} + \alpha ) - \beta_{B} Z- \lambda_{B} & \beta_{B} U & \beta_{B} U \\ \beta_{T} - \beta_{T} Z & - ( \mu_{B} + \alpha ) - \beta_{B} Z - \beta_{T} V- \mu_{T} p & - ( \mu_{B} + \alpha ) \\ 0 & \beta_{B} Z & - \lambda_{B} - \beta_{T} V- \mu_{T} p \end{array}\displaystyle \right \vert , \\& \det \bigl( J^{[2]} ( E_{1} ) \bigr) \\& \quad = - \bigl[ \bigl( ( \mu_{B} + \alpha ) + \beta_{B} Z+ \lambda_{B} \bigr) \bigl( ( \mu_{B} + \alpha ) + \beta_{B} Z + \beta_{T} V+ \mu_{T} p \bigr) ( \lambda_{B} + \beta_{T} V+ \mu_{T} p ) \bigr] \\& \quad \quad{} + \beta_{T} \beta_{B} U(1-Z)[ \beta_{B} Z+ \lambda_{B} + \beta_{T} V+ \mu_{T} p ]- \bigl( ( \mu_{B} + \alpha ) + \beta_{B} Z+ \lambda_{B} \bigr) \bigl( ( \mu_{B} + \alpha ) \beta_{B} Z \bigr) \\& \quad \leq - \bigl[ \bigl( ( \mu_{B} + \alpha ) + \beta_{B} Z+ \lambda_{B} \bigr) \bigl( ( \mu_{B} + \alpha ) + \beta_{B} Z + \beta_{T} V+ \mu_{T} p \bigr) ( \lambda_{B} + \beta_{T} V+ \mu_{T} p ) \bigr] \\& \quad\quad{} + \beta_{T} \beta_{B} [ \beta_{B} Z+ \lambda_{B} + \beta_{T} V+ \mu_{T} p ] - \bigl( ( \mu_{B} + \alpha ) + \beta_{B} Z+ \lambda_{B} \bigr) \bigl( ( \mu_{B} + \alpha ) \beta_{B} Z \bigr) \\& \quad =- ( \lambda_{B} + \beta_{T} V+ \mu_{T} p ) \bigl[ ( \mu_{B} + \alpha+ \beta_{B} Z+ \lambda_{B} ) ( \mu_{B} + \alpha+ \beta_{B} Z + \beta_{T} V+ \mu_{T} p ) - \beta_{T} \beta_{B} \bigr] \\& \quad\quad{} - \beta_{B} Z \bigl[ ( \mu_{B} + \alpha + \lambda_{B} + \beta_{T} V ) ( \mu_{B} + \alpha ) - \beta_{T} \beta_{B} \bigr]. \end{aligned}$$

Analyzing the terms of equality above, we have

$$\begin{aligned}& ( \mu_{B} + \alpha+ \beta_{B} Z+ \lambda_{B} ) ( \mu_{B} + \alpha+ \beta_{B} Z + \beta_{T} V+ \mu_{T} p ) > \beta_{T} \beta_{B}, \\& ( \mu_{B} + \alpha + \lambda_{B} + \beta_{T} V ) ( \mu_{B} + \alpha ) > \beta_{T} \beta_{B}. \end{aligned}$$

Then $\det ( J^{[2]} ( E_{1} ) ) <0$, and from Lemma 2, the EE point $E_{1}$ is locally asymptotically stable. Hence the end of the proof of Theorem 5. □

4 Numerical simulations

In this section, we simulate different possible scenarios to check the effect that some values of fractional exponent ϕ have on the dynamics of bovine babesiosis disease and tick populations. For comparison purposes, we will use the same parameters as Aranda et al. [3].

4.1 Adams-Bashforth-Moulton method

For numerical elucidations of system (17), one can use the generalized Adams-Bashforth-Moulton method. To provide the estimated elucidation by means of this algorithm, consider the following nonlinear fractional differential equation [41]:

$$ \begin{aligned} &D_{t}^{\alpha} y ( t ) =f \bigl( t,y ( t ) \bigr), \quad 0\leq t\leq T, \\ &y^{ ( k )} ( 0 ) = y_{0}^{(k)},\quad k=0,1,2, \ldots,m-1, \mbox{where } m= [ \alpha ]. \end{aligned} $$

(39)

The equation is equivalent to the Volterra integral equation

$$ y ( 0 ) = \sum_{k=0}^{m-1} y_{0}^{(k)} \frac{t^{k}}{k!} + \frac{1}{\Gamma (\alpha)} \int_{0}^{t} (t-s )^{\alpha-1} f \bigl(x, y(t) \bigr)\,ds. $$

(40)

Diethelm et al. used the predictor-corrector scheme [42–44] based on the Adams-Bashforth-Moulton algorithm to integrate (40). Also, by setting $h= \frac{T}{N}$, $t_{n} =n h$, and $n=0,1,2,\dots,N\in Z^{+}$, (17) can be discretized as follows [41]:

$$\begin{aligned}& \begin{aligned} U^{n+1} &=U(0)+ \frac{h^{\phi_{1}}}{\Gamma ( \phi_{1} +2 )} \bigl( ( \mu_{B} + \alpha ) \bigl( 1- U_{n+1}^{p} - V_{n+1}^{p} \bigr) - \beta_{B} U_{n+1}^{p} Z_{n+1}^{p} \bigr) \\ &\quad{} + \frac{h^{\phi_{1}}}{ \Gamma ( \phi_{1} +2 )} \sum_{j=0}^{n} a_{j,n+1} \bigl( ( \mu_{B} + \alpha ) ( 1- U_{j} - V_{j} ) - \beta_{B} U_{j} Z_{j} \bigr), \end{aligned} \\ & \begin{aligned} V^{n+1} &=V(0)+ \frac{h^{\phi_{2}}}{\Gamma ( \phi_{2} +2 )} \bigl( \beta_{B} U_{n+1}^{p} Z_{n+1}^{p} - \lambda_{B} V_{n+1}^{p} \bigr) \\ &\quad\quad{} + \frac{h^{\phi_{2}}}{\Gamma ( \phi_{2} +2 )} \sum_{j=0}^{n} a_{j,n+1} ( \beta_{B} U_{j} Z_{j} - \lambda_{B} V_{j} ), \end{aligned} \\ & \begin{aligned} Z^{n+1} &= Z (0)+ \frac{h^{\phi_{3}}}{\Gamma ( \phi_{3} +2 )} \bigl( \beta_{T} \bigl( 1- Z_{n+1}^{p} \bigr) V_{n+1}^{p} - \mu_{T} p Z_{n+1}^{p} \bigr) \\ &\quad{} + \frac{h^{\phi_{3}}}{\Gamma ( \phi_{3} +2 )} \sum_{j=0}^{n} a_{j,n+1} \bigl( \beta_{T} ( 1- Z_{j} ) V_{j} - \mu_{T} p Z_{j} \bigr), \end{aligned} \end{aligned}$$

where

$$\begin{aligned}& U_{n+1}^{p} =U(0)+ \frac{1}{\Gamma ( \phi_{1} )} \sum _{j=0}^{n} b_{j,n+1} \bigl( ( \mu_{B} + \alpha ) ( 1- U_{j} - V_{j} ) - \beta_{B} U_{j} Z_{j} \bigr), \\ & V_{n+1}^{p} =V(0)+ \frac{1}{\Gamma ( \phi_{2} )} \sum _{j=0}^{n} b_{j,n+1} ( \beta_{B} U_{j} Z_{j} - \lambda_{B} V_{j} ), \\ & Z_{n+1}^{p} =Z(0)+ \frac{1}{\Gamma ( \phi_{3} )} \sum _{j=0}^{n} b_{j,n+1} \bigl( \beta_{T} (1- Z_{j} ) V_{j} - \mu_{T} p Z_{j} \bigr), \end{aligned}$$

with

$$a_{j,n+1} = \textstyle\begin{cases} n^{\phi_{i} +1} -(n- \phi_{i} )(n+1 )^{\phi_{i}}, &j=0,\\ (n-j+2 )^{\phi_{i} +1} +(n-j )^{\phi_{i} +1} -2(n-j+1 )^{\phi_{i} +1},& 1\leq j\leq n,\\ 1, & j=n+1, \end{cases} $$

and

$$b_{j,n+1} = \frac{h^{\phi_{i}}}{\phi_{i}} \bigl( ( n-j+1 )^{\phi_{i}} - ( n-j )^{\phi_{i}} \bigr), \quad 0\leq j\leq n, $$

with $i=1,2,3$.

4.2 Disease-free equilibrium

Figure 1

Dynamic of bovine babesiosis disease U , V , and Z with $\pmb{\phi_{1} = \phi_{2} = \phi_{3} =1}$ .

Figure 2

Dynamic of U with $\pmb{\phi_{1} =1}$ (solid line), $\pmb{\phi_{1} =0.9}$ (dotted dashed line), $\pmb{\phi_{1} =0.8}$ (dashed line), and $\pmb{\phi_{1} =0.7}$ (dotted line).

Figure 3

Dynamic of V with $\pmb{\phi_{2} =1}$ (solid line), $\pmb{\phi_{2} =0.9}$ (dotted dashed line), $\pmb{\phi_{2} =0.8}$ (dashed line), and $\pmb{\phi_{2} =0.7}$ (dotted line).

Figure 4

Dynamic of Z with $\pmb{\phi_{3} =1}$ (solid line), $\pmb{\phi_{3} =0.9}$ (dotted dashed line), $\pmb{\phi_{3} =0.8}$ (dashed line), and $\pmb{\phi_{3} =0.7}$ (dotted line).

4.3 Endemic equilibrium

Figure 5

Dynamic of bovine babesiosis disease U , V , and Z with $\pmb{\phi_{1} = \phi_{2} = \phi_{3} =1}$ .

Figure 6

Dynamic of U with $\pmb{\phi_{1} =1}$ (solid line), $\pmb{\phi_{1} =0.9}$ (dotted dashed line), $\pmb{\phi_{1} =0.8}$ (dashed line), and $\pmb{\phi_{1} =0.7}$ (dotted line).

Figure 7

Dynamic of V with $\pmb{\phi_{2} =1}$ (solid line), $\pmb{\phi_{2} =0.9}$ (dotted dashed line), $\pmb{\phi_{2} =0.8}$ (dashed line), and $\pmb{\phi_{2} =0.7}$ (dotted line).

Figure 8

Dynamic of Z with $\pmb{\phi_{3} =1}$ (solid line), $\pmb{\phi_{3} =0.9}$ (dotted dashed line), $\pmb{\phi_{3} =0.8}$ (dashed line), and $\pmb{\phi_{3} =0.7}$ (dotted line).

5 Conclusions

We have obtained the worldwide asymptotical stability of disease-free equilibrium using comparison theory of fractional differential equations since $R_{0} < 1$. Therefore the proof that the endemic equilibrium point, when $R_{0} > 1$, $\mu_{B} + \alpha > \beta_{B}$, and $\mu_{B} + \alpha > \beta_{T}$, is locally asymptotically stable was attained using the linearization theorem for fractional differential equations. Moreover, if $R_{0} < 1$, then the system evolves to the endemic equilibrium point. To return to a disease-free status, the $R_{0}$ value should be greater than 1. $R_{0} < 1$ is achieved when parameters $\beta_{B}$ and $\beta_{T}$ are very small or when parameters $\lambda_{B}$, $\mu_{T}$, and p are very large. Therefore, a biological strategy to combat babesiosis disease would have to focus on one of these parameters. These results were confirmed by numerical simulations using the Adams-Bashforth-Moulton algorithm. Numerical simulations of an improved epidemic model with arbitrary order have shown that fractional order is related to relaxation time, in other words, the time taken to reach equilibrium. The chaotic behavior of the system when the total order of system is less than three is sketched. A comparison between four different values of the fractional order is shown in Figures 1, 2, 3, and 4, with the same control parameter as $\mu_{B} =0.0002999$, $\alpha=0.001$, $\beta_{B} =0.006$, $\lambda_{B} =0.000265$, $\beta_{T} =0.00048$, $\mu_{T} =0.001609$, $p=0.1$. Figures 1, 2, 3, and 4 show different behaviors for $\phi =0.7$, $\phi =0.8$, $\phi =0.9$, and $\phi=1$. For all four cases, the disease evolves to the disease-free equilibrium point and endemic equilibrium point; however, it is slower when $\phi=0.9$, when $\phi=0.8$, it is slower than $\phi=0.9$. And it is much slower when $\phi=0.7$. Numerical simulations with different order show that the system decays to equilibrium condition like power law $t^{- \phi}$, as previously established in [45]. This result provides an important insight about the use of fractional order to model the dynamics of babesiosis disease and tick population. The proof shown here should be used as a guide in the study of equilibrium conditions in similar problems, such as tuberculosis [46], malaria [47], or toxoplasmosis disease [48].