Smokin’ Joe,
The problem here is that what is happening with Ebola is not new for viral diseases.
Given the number of survivors in East Africa and the reality of “Persistent Viral Infections”, Ebola is now endemic to East Africa, period. Dot.
See:
Chapter 46 Persistent Viral Infections
Istvan Boldogh, Thomas Albrecht, and David D. Porter.
http://www.ncbi.nlm.nih.gov/books/NBK8538/
“General Concepts
Definition
Persistent infections are characterized as those in which the virus is not cleared but remains in specific cells of infected individuals. Persistent infections may involve stages of both silent and productive infection without rapidly killing or even producing excessive damage of the host cells. There are three types of overlapping persistent virus-host interaction that may be defined as latent, chronic and slow infection.
Pathogenesis
The mechanisms by which persistent infections are maintained involve both modulation of virus and cellular gene expression and modification of the host immune response. Reactivation of a latent infection may be triggered by various stimuli, including changes in cell physiology, superinfection by another virus, and physical stress or trauma. Host immunosuppression is often associated with reactivation of a number of persistent virus infections.
Persistent Infections by Organ System
Some viruses can establish persistent infection at the same time in different cell types of one or more tissues or organs. For example, the primary site for latency of cytomegalovirus is thought to be peripheral blood monocytes, but the virus may induce disease and can be detected in cells of several organs (e.g., kidney, lung, and those of the digestive or central nervous system). Table-1 categorizes selected human viruses by organ systems in which the virus is believed to be primarily persistent.
In Vitro Models of Persistence
Three kinds of persistent infection can be maintained in cell cultures: chronic focal, chronic diffuse, and latent. These infections may model key aspects of persistent infections in vivo.
Control
No measures to eradicate persistent viruses have been developed. Vaccination, interferon and antiviral drugs can reduce the frequency of clinical recurrence and ameliorate clinical symptom, yet the virus continues to remain associated with the host.
Go to:
Introduction
Medical science has begun to control a number of acute virus infections, many by drug treatment and/or immunization, but persistent virus infections are largely uncontrolled. Diseases caused by persistent virus infections include acquired immune deficiency syndrome (AIDS), AIDS-related complexes, chronic hepatitis, subacute sclerosing panencephalitis (chronic measles encephalitis), chronic papovavirus encephalitis (progressive multifocal leukoencephalopathy), spongioform encephalopathies (caused by prions), several herpesvirus-induced diseases, and some neoplasias. The pathogenic mechanisms by which these viruses cause disease include disorders of biochemical, cellular, immune, and physiologic processes. Ongoing studies are rapidly advancing our understanding of many persistent infections. Viruses have evolved a wide variety of strategies by which they maintain long-term infection of populations (see Ch. 48), individuals, and tissue cultures. This chapter primarily describes persistent infections in vivo and focuses on viruses that persist in humans.”
>snip<
Thanks! Like Chicken Pox and Shingles, the virus persists after the initial infection is over, and the recurrence can take a different form.
That’s an interesting article—it caught my attention until my husband came down and said, “Shouldn’t you be getting ready for work?”
I will say, however, that I am unaware of any particular features of Ebolavirus that would cause it to be able to establish a low-level persistent infection. For one thing, it is a strictly RNA virus, with no DNA intermediate. Thus, it cannot conceal its genetic material within the host cell, either integrated into the chromosome or as an extra-chromosomal plasmid.
The only comparable virus that can hide in the body for long periods is the measles virus. I do not have time (and will not for the next several days) to compare the genomes of measles and Ebola to see if there are comparable features that would suggest that a similar mechanism in Ebola is plausible.
So far, the Ebolavirus has been shown to “survive” in immune privileged sites such as the seminal vesicles and interior of the eyes. I think that this is a purely physical presence, and that the virus is stabilized by the controlled pH and salt content of the fluids, rather than its establishing a low-level infection in those areas. I would think that as the fluids in those sites are slowly replaced, the virus will slowly be removed through dilution (and the removed virus will be destroyed by the immune system).