For other insect hosts, risk of exposure as well as the type of challenge an individual is exposed to has explained how investment into immunity is optimised and subsequently how costs of resistance are minimised [ 41, 42].
Because hosts are capable of clearing A. phagocytophilum infections (13 ), surveys of host exposure might not represent species-specific probabilities of transmitting the pathogen to uninfected ticks.
In the laboratory, animal-to-animal transmission of Pneumocystis spp. has been demonstrated both by immunocompromised and immunocompetent hosts after periods of exposure as short as 1 day (22, 23 ).
The frequency of infection depends on several factors including the nature of the habitat, the population densities of dogs and vectors, the presence of other possible hosts, the level of exposure to vectors and the proper use of vector repellents [ 22, 23].
Researchers have now found that bacteria can become resistant to a host of antibiotics through exposure to a toxin from another bug.
A feature of schistosome epidemiology is that infection intensity and disease severity vary considerably between geographic areas and between individuals within the same region whether due to age and duration of exposure, host or parasite genetic background and/or host behaviour.
These sequences provide for a platform from which further proteomic studies may be designed to identify salivary proteins from T. bromius that are of pharmacological interest or used as immunological markers of host exposure.
We assume that this new host has no history of exposure, nor any acquired immunity.
Under the assumption that more than one P. ramosa spore penetrates the host during seven days of exposure, the present study provides additional support for the prediction that high relatedness selects for prudent exploitation and thus low virulence.
In the real world, these variables work simultaneously, along with a host of other chemical exposures, to produce effects that vary by individual.
