Parasites and wildlife in a changing world: The vector-host- pathogen interaction as a learning case

Rizzoli, Annapaola; Tagliapietra, Valentina; Cagnacci, Francesca; Marini, Giovanni; Arnoldi, Daniele; Rosso, Fausta; Rosà, Roberto

Vectorial capacity (VC) is crucial at predicting changes in disease hazard and the emergence of vector-borne infections. Firstly developed as an index for exploration of control methods for malaria and other mosquito-borne diseases of humans (MacDonald, 1955) , its adaptation to mosquito and tick borne zoonoses, which usually imply more than one reservoir host species, requires particular attention. In general, vectorial capacity describes the dynamic relationship between vectors of infectious disease agents and the vertebrate hosts. It combines the physiological and genetic attributes of vectors that determine their susceptibility to infection and their ability to transmit pathogens with relevant ecological and behavioural traits of vectors such as longevity, host preference and host abundance (Eldridge and Edman, 2004) . In the case of mosquito borne diseases, the concept of VC is the measure of a mosquito population's capacity to transmit an infectious agent to a new susceptible population. It does not integrate biotic and abiotic factors explicitly, but variables which are affected by those agents. This can enable a clearer understanding of the impact of each on transmission of mosquito-borne pathogen (Kramer and Ciota, 2015) . Vectorial capacity is the expected number of hosts infected per infected host assuming perfect vector efficiency, and can be expressed, in the case of mosquitoes, as follows (Smith and McKenzie, 2004; McMillan et al., 2019) :