The distribution of pathogens over their hosts, and the distribution of different pathogens within a host species, will affect the frequency of multiple infection of an individual host by different pathogens.
The tests analyse the homogeneity of distribution of a pathogen over different host species or populations, and of different pathogens on a host, and analyse how significantly the values of the indices departs from zero (i.e. no association).
Comparative genomic analyses of xanthomonads have greatly facilitated our understanding of the virulence factors and host range determinants of different pathogens [ 8- 10].
We can therefore ask if, as a result of these processes, a landscape constituted by different hosts will produce a mosaic of different pathogen populations, each specialised on a host species.
To test for association of different pathogens within a host, or for a given pathogen across different hosts, we follow the same process, as the expectation of a sum of observations will be equal to the sum of their expectations, and the corresponding sums of observations will be binomially distributed given the Xik.
Animal or plant species may be hosts for a range of pathogens, and most host populations encounter a large number of different pathogen species [8].
Glycans take active part in many physiological processes, but they are also involved in pathological processes as well, triggered by adhesion of different pathogens to host tissues, in neurological disorders and in cancer.
Depending on the specific interactions of different pathogens with their hosts, a Cxcr3.2-dependent response could be beneficial for the resolution of infection or have an unfavorable effect because, on the one hand, it can sustain the recruitment of macrophages to the infection site, but, on the other hand, it can promote the dissemination of bacteria, as in the case of mycobacterial infection.
These different lines of evidence all suggest that serum starvation might impact on the recognition of different pathogen species by the host cell.
First, we propose indices for the observed patterns of host infection by different pathogens, and the observed patterns of co-infection, and tests to analyse if they conform to the null hypothesis of randomness or reflect associations.
