Cascading effects of sand stabilization on pathogen communities: Connecting global and local processes

Abstract

Aim: To advance our understanding of the mechanisms that mediate the relationships between global climatic and anthropogenic processes and pathogen occurrence, it is crucial to evaluate the exact pathways connecting the ecological mediators and the pathogen responses across spatial and temporal heterogeneities at various scales.We investigated the pathways connecting these two types of heterogeneities in sand stabilization that were created by contrasting forces of various human activities and long-term droughts, and pathogen occurrence in host populations. The considered candidate ecological mediators were various components of host community structure, arthropod vector traits, and the pathogen occurrence in these vectors.Location: North-western Negev Desert's sands in Israel.

Bartonella infections are prevalent in rodents despite efficient immune responses

“…Contrary to our hypothesis that at least one of the rodent species would exhibit a waning immune response, as mentioned above, we found that infection with B. krasnovii A2 strain elicited an efficient and protective immune response in all of the species tested. Yet, despite the similar microhabitats of G. gerbillus and G. pyramidum [ 34 ], and the similar body size of G. gerbillus and G. andersoni [ 57 ], our results indicate that the immune response of G. gerbillus may be more reactive than those of the two other species. This was demonstrated by the magnitude of the increases in antibody levels following reinfections compared to the primary responses, which were highest in G. gerbillus (Fig.…”

“…We also tracked Bartonella -specific IgG antibody levels in these animals over 140 days after the first inoculation and 60 additional days following their re-exposure to the same strain. In nature, the mean longevity of the three rodent species ranges from 6.5 to 12 months [ 34 , 46 , 47 ]. Thus, the 200-day duration of this experiment likely allowed for a decent approximation of the infection dynamics that these rodents may experience in nature.…”

“…Thus, the greater resistance of G. gerbillus may indicate that this host is more adapted to Bartonella than the two other species. However, considering the sporadic temporal and spatial occurrence of G. gerbillus as compared to the steady occurrence of G. andersoni and G. pyramidum rodents in the natural environment [ 34 ], it is unlikely that G. gerbillus faces strong selection due to infections with B. krasnovii A2 strain. Instead, assuming that Bartonella is ahead of its hosts in the evolutionary arms race, the higher bacterial loads in G. andersoni and G. pyramidum compared to G. gerbillus may indicate that B. krasnovii A2 strain is more adapted to these more reliable hosts, and can therefore better hide and/or escape from their IgG antibodies [ 63 , 64 ].…”

“…The three rodent species in our study coexist in the sand dunes of the northwestern Negev Desert in Israel [ 34 , 38 , 39 ]. All of the individual animals that were used in the experiments were from a laboratory colony maintained by HH.…”

“…Despite this efficient immunological response, 75–100% of the rodents in this region are infected with Bartonella at any given time [ 31 – 33 ]. Second, these are source rodent communities in which the same host individuals have lifetimes of about 1 year and are only negligibly affected by these bacterial infections [ 25 , 32 , 34 ]. Moreover, in most years, the appearance of new juveniles is restricted to about 2 months of the year [ 32 ].…”