Sarcoptes scabiei: histopathological changes associated with acquisition and expression of host immunity to scabies.

The sequential changes in the histology in scabietic lesions were investigated for hosts (rabbits) during sensitization and reinfestation with Sarcoptes scabiei. Experimentally infested naive hosts developed heavy scabies infestations but 65% of the hosts showed induced immunity (resistance) to reinfestation. All hosts (naive, immune, and susceptible) exhibited an initial cell infiltrate in scabietic lesions that consisted predominantly of neutrophils and a few macrophages. This was followed by a dense plasma cell infiltrate. Upon reinfestation the progression of neutrophil infiltration was faster and the response was greater in hosts who acquired immunity than those in the susceptible hosts.