Dr. Dan Weinreich Response: Ebola A Global Public Health Concern
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Capstone Colloquium in Evolutionary Medicine 01:070:491 Dr. Robert Scott Dr. Dan Weinreich Visit Response Stephen Daire
In 1976 perpetuated extraction of resources from increasingly inaccessible areas prompted the primary epidemic of Ebolavirus by pushing the virus into contact with people. Though it is unclear how ebola became transmitted to humans one possible origin of the virus’ spread is through bushmeat hunting. Since its emergence ebola has caused 26 outbreaks in 10 countries; Congo, Gabon, Guinea, Sierra Leone, Liberia, Mali, United States of America, Nigeria, Senegal, Spain and the Democratic Republic of Congo. With 19,497 cases and 7,588 deaths, a 39% mortality rate, ebola represents a growing global health concern. Ebola has become a prominent threat to human populations which requires intervention. The logic that infection will subside quickly is flawed; without a swift reaction there is no cause for subsidence. In epidemiology there’s an obligatory response to outbreaks as public health is a pannational concern. In the past ebola’s transmission and mobility was hindered by several ecological factors lower population density, a lack of an evolutionary relationship with humans, and limited transportation. The United States of America was able to treat cases with interferon and intravenous saline due to its available medical infrastructure in recent cases. New pharmaceuticals such as biosynthetic ZMapp, an antibiotic cocktail, and others have offered some relief from the hemorrhagic fever, yet they are just as likely of killing the patient as saving them. Lack of effective treatment regimes, aid, and medical infrastructure in Africa caused the 2014 outbreak be much larger than prior outbreaks. Issues promoting the continuation of ebola outbreaks and ecological conditions along with other parallels in the establishment of HIV into the infectious disease repertoire have lead researchers to the find that ebola is doing something few considered. Ebola has possibly been asymptomatic in the population since the 1970s. It may also be headed toward fixation and
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endemicy in some regions of Central Africa. A study discovered that during the establishment of HIV selection occurred within and between patients swamped with viral mutants. Selection dealt with excessive virulence with decreased transmission and began to create asymptomatic variants to promote continuation of the virus. This study was carried out through a gene survey of areas with high densities of HIV infected individuals with a focus on sex workers. CCR5 was identified as a mutation in the human genome leading to a missing primary site on the cell membrane for HIV incursion. CCR5 leads to a 2% HIV immunity in the populations studied based on major histocompatibility complex ( MHC). This was an effective genomic study and accounted for more than 40% variance in HIV. Ebola has functioned in much the same manner. The two variants of the 5 from genus Ebolavirus caused the 2014 outbreak. Patient Zero was a traditional healer who performed a funeral which included body touching; a cultural norm in Central Africa that is not present in Eastern Africa. Ebola then traveled to Sierra Leone via the healer. This was most likely a lucky transmission which had a mutant with a high prevalence for transmissibility. G enomic surveillance elucidates Ebola virus origin and transmission during the 2014 outbreak (Gire et al.) has found the possible loci responsible the variation in these populations. They also observed the prevalence of high conservation in a catalogue of 395 mutations, of which 50 were nonsynonymous at 8 loci. These conserved loci most likely correlate to the functions of virulence and transmission. Further functional analyses will exemplify the possible mutations leading to ebola immunity. Until that time, a continued policy of active and passive infectious disease control must be maintained in order to prevent the more virulent forms from reproducing. European union models of mandatory quarantine for methicillinresistant S. aureus (MRSA) would be
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effective mandatory procedure for ebola in all nations depending on infrastructure. The model, being the initial quarantine of patients no matter the cause for medical attention and release after viral subsidence, aims to prevent further infection. This ultimately relates to issues of investment in preventative care. With higher investments paying off more in the long term, and smaller investments paying off exponentially less, a crucial ecological difference between outbreaks was investment, particularly in capital. Ebola is a difficult disease to detect and treat even with well funded and equipped professional medical staff. The tests required to locate ebola operate on presence of levels of antibiotics in the blood stream. If the virus has recently infected the host their count maybe too low to register as positive for the virus. This allows the virus to remain in the population until morbidity ensues. The patient then seeks aid or dies. Along the way ebola infects any person they come into physical contact with. The vectors of transmission for ebola are not known, and their discovery will be a crucial step in handling this disease. The sociomedical response for the 1976 outbreak lead the CDC to send doctors to Zaire. The 2014 outbreaks saw other differences in ecological factors: nonresponsive, no research nor treatment funding. The rationale of letting the infection exhaust itself is also attested to in the distribution of ebola serum to doctors during only the infections of 1976. ZMapp is dangerous, inefficient, expensive and limited in quantity as it is still not in pharmaceutical production. ZMapp and drugs like it were only distributed to the most in need, usually medical staff, upon consented request in 2014. Lack of foreign medical aid and sick medical staff caused a treatment vacuum with patients and caregivers sharing adjacent gurneys. With populations growing and showing no sign of stopping in Central and Eastern Africa (Democratic Republic of Congo with 23.55 million in
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1976 and 67.51 million 2010 as well as Sierra Leone with 2.8 million in 1976 and 6.06 million 2013) ebola will have no shortage of hosts in the future. This will allow for a sizeable mobile population, with a connection to the natural reservoir. So long as prevailing public health rationale remains unchanged ebola will thrive in the human population with minimal selection pressure. Natural selection has no room for accommodation, in the viruses sense. Viruses see yesterday's dividends and nothing more, there is no generational viral selfperspective. So why has there been a changed response on the part of humanity when we have more antivirals? Is it the possibility of a protracted fight with little benefit? The fight against ebola may be a protracted one but the benefits of public health projects are seldom miniscule. Public health programs, such as the Tennessee Valley Authority’s malaria controls national, are very successful at controlling evolutionary trajectories of infections. Programs benefit humanity by producing new clinical procedure and pharmaceuticals as they attempted new novel methods of treatment. These projects have eradicated, or subdued the infections to the ends that these disease have been brought to heel, and decreased their virulence. With a noquarter perspective, ebola lacks a need to reduce its virulence and focuses on shorter generation gaps. It will complete its infection cycle and kill the host. Or, it is passed to a new host and continues increasing transmission. There is no precedent for change with no selection pressure. Ignoring a problem only allows it to fester. With ebola expected outcomes liklely include increased virulence and transmission. Coupled with generalization and fixation due to high prevalence in the human population. Minimization of virulence, and effective public health stratagem, will come from an increased focus on the evolutionary perspective on Ebolavirus .
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