The effect of age on the infection and immunoresponsiveness of mice to Babesia microti

Age‐Associated Decline in Resistance toBabesia microtiIs Genetically Determined

“…In contrast, old BALB/c and C57BL/6 mice cleared parasites at the end of the early phase and did not suffer from recrudescent parasitemia. Although adaptation was required to increase the virulence of the Peabody strain used by Habicht et al [12], infection with our clinical isolate RM/NS resulted in high levels of parasitemia, without the need for adaptation. When infected with a number of organisms similar to the inoculum delivered by naturally infected ticks, perhaps on the order of у25,000 sporozoites [20], BALB/c mice were as resistant as C57BL/6 mice to RM/NS.…”

“…These studies may have limited value for understanding human disease, because B. bovis is not pathogenic in people. There has been only 1 study [12] assessing the effect of age on the resistance of laboratory mice to the human pathogen B. microti. Although infection tended to resolve faster in younger BALB/c mice, peak levels of parasitemia were higher in older BALB/c mice.…”

“…There has been a single, unsuccessful attempt to show agerelated differences in susceptibility to a laboratory mouseadapted strain of B. microti [12]. In the present study, we report the use of a novel B. microti clinical isolate that reliably infects several inbred mouse strains.…”

Babesiosis

“…It has been observed that adult P. leucopus are more frequently parasitemic than juveniles (215). Another study showed that older laboratory (BALB/c) mice had reduced and delayed peak parasitemias compared with more juvenile mice but that the older mice could not clear the parasites and experienced periodic parasitemias until death (74). Also, resistance to B. divergens is seen in young cattle (17).…”

Effect of Sex Steroids on Babesia microti Infection in Mice

“…strain WA1, and susceptible mouse models. [23][24][25][26][27][28][29] Aguilar-Delfin and others reported a sex-related influence on resistance to acute Babesia sp. strain WA1 infection in C57BL/6 mice, with males being more resistant than females.…”