CCR2 and disease arising from reactivation of latent virus: The up-regulation of differentiated macrophage and the CCR2 together indicate that microsporidia infection stimulates more macrophages to this immune response, yet maybe later or during long-term latent infection, these immune cells would be hijacked to act as a “Trojan horse”, which had been found under the infection of Encephalitozoon cuniculi [10,31].