Latent Pathogens and Quasi-Latent Pathogens-The Differences and Similarities

Many pathogens have evolved capabilities for maintaining chronic infections by entering one or more stages of latency to avoid immune system detection and attack. Several latent pathogens are capable of periodic reactivations decades after their initial infections. However, other pathogens have not evolved intrinsic capabilities for latency to maintain chronic infections, but several of these pathogens can maintain chronic infections by what herein will be called "quasi-latency" in response to suppressions or nutrient deprivation. When later events reduce such suppressions, the quasi-latent pathogens can achieve "resurgent" infections. These quasi-latent pathogens can quickly achieve resurgent infections, which are severe and frequently lethal. This raises the question of how some pathogens can be suppressed into quasi-latency, and how they can become resurgent. Besides innate and adaptive immune cell actions that kill pathogens or pathogen-infected cells, pathogens can be suppressed by nutritional deprivation. Iron deprivation is frequently effective, since iron is essential for pathogens. For instance, hemolytic protozoan parasite infections can provide heme and iron for the resurgence of quasi-latent, iron-deprived pathogens. This could explain the pathogenesis of two puzzling, sometimes lethal pregnancy disorders, pre-eclampsia and eclampsia, which have caused the deaths of millions of women for centuries.