Building materials as well as building design can have an impact on the accessibility of rodents to the houses. The number of burrows in the house and the hygiene of the immediate surrounding environment have been suggested as well as risk factors for rodent infestation and transmission of Lassa virus. The uses of the house might also have an impact on the presence and extended activity of M. Natalensis in West Africa as compare to studies in Tanzania. Some of the factors to have in mind are: the arrangement of furniture, the darkness of the houses, having doors and windows open, or doors and windows with gaps. Another consideration is the access to alternative building materials, such as cement, the cost of this material in relation to the household’s usual expenditure and the ease to which this can be accessed, both by the individuals and within different sized markets. Alongside this the local history of a region may contribute greatly to the presently used building materials, such as the increase in temporary accommodations in the aftermath of the civil war in Sierra Leone.