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Modern Geomatics Technologies and Applications

1. Importing the prepared layers into the NetLogo 6.0.4 platform.
2. Correspondingly assigning the values of imported layers to the cells.

By doing these two phases, the environment of our agent-based model was created. It should be noted that the cell size
of the simulated model was considered 35 meters due to the mosquito’s perception-range (i.e., 50 meters) as well as in order to
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consider the mosquito’s movement based on the Moore neighbourhood.
Creating agents and also distributing them in the environment is the objective of the second step. To do so, the following
phases were performed.

1. Creating human agents commensurate with the population of each village and city of the Saravan county and
distributing them randomly within their own village or city’s boundary.
2. Defining some attributes for human agents with regard to the aim of the research.
3. Creating mosquito agents and considering some attributes for them according to their characteristics in the real world
as well as with regard to the research’s objective.
4. Initializing the values of mosquito agents’ attributes regarding reality or randomness based on the normal distribution.
5. Randomly distributing mosquito agents in the boundary of Saravan county.

With regard to the two steps described, the environment of our agent-based model has been created and all agents have
been created and distributed in the environment.
Modelling the movements and interactions of agents is the objective of the third step. To pursue this objective, agents
were classified into two groups of static and mobile. In reality, humans usually work outside their homes from sunrise to sunset
and rest in their homes from sunset to sunrise, and on the other hand, because mosquitoes seek humans from sunset to sunrise;
therefore, the movement of human agents was neglected [12]. Despite human agents assumed as static agents, mosquito agents
were presumed as motile agents.
Anopheles mosquitoes keep moving until they reach the human’s blood or water sources; Alternatively, the maximum
distance that Anopheles mosquitoes can fly daily is approximately 250√2 meters [19]; therefore, due to this distance as well as
the cell size of the model (i.e., 35 meters), mosquito agents can move up to 10 cells per day. The movement of mosquito agents
was considered in two ways: randomly and directional. They move randomly as long as there will be no human agents in one of
the eight cells in the Moore neighbourhood, while in the case of existence of even a human agent in one of the eight surrounding
cells, they will move to that cell (i.e., directional movement).
Once Anopheles mosquitoes succeed in finding humans and feeding on their blood, rest for about 2-3 days to digest the
blood for the reproduction [20]. After that, they seek a place containing water to lay the eggs. Regarding the perception-range of
mosquitoes, in this case, the movement of mosquito agents was considered either randomly or directionally, as well; as long as
the water cell is not present in any eight cells surrounding the cell in which the mosquito agent is located, the mosquito agent
moves randomly; while if there is a water cell, mosquito agent moves to that cell.

2.3.2. The SEIRS model: At any moment in our model, mosquito agents are in one of three states: susceptible, exposed, and
infected and human agents are in one of four states: susceptible (S), exposed (E), infected (I), and recovered (R). In order to
simulate the spread of malaria among human agents, the Susceptible-Exposed-Infected-Recovered-Susceptible (SEIRS) model
was used. In that way, human agents are initially susceptible to the disease; while if the susceptible human agent is bitten by an
infected mosquito agent, the human agent is likely to be exposed, depending on the probability of infection transmission
calculated by the cell. In the exposed state, the symptoms of the disease do not appear, which is called the disease incubation
period. The incubation period for malaria in humans is usually 7 to 30 days [21]. In the event that the exposed human agent is
bitten by the susceptible mosquito, the parasite belonged to the malaria disease cannot be transmitted to the mosquito. At the end
of the incubation period of the disease, the human agent becomes infected (i.e., in this case, the symptoms of the disease appear).
In this case, if the human agent is bitten by susceptible mosquito agents, the parasite can be transmitted to them. The infected
human agent after passing the infectious period of the disease becomes recovered. The probability of becoming recovered of
infected human agents (the probability of turning the state of the human agent from infected into recovered) is considered as a
product of 0.037 multiplied by the number of days elapsed after getting infected [22]. In the SEIRS model, once human agents
become recovered, do not remain immune against malaria and become susceptible again after a while. The probability of turning
the human agent’s state from the recovered into the susceptible is considered as a product of 0.01 in the number of days elapsed
after getting recovered [22]. Fig.2 illustrates the diverse types of human agents’ states as well as how human agents pass through
different states.

1 The Moore neighbourhood of a cell consists of the cell itself and the eight cells surrounding it.
3