Hantavirus: An Overview Virulence: Hantavirus

Hantavirus: An Overview

Virulence:

Hantavirus is an infectious disease communicated by rodent carriers through droppings or saliva and absorbed by human beings through airborne channels. (CDC) The condition is somewhat rare, particularly in the Western Hemisphere, and has only be identified as early as the 1950s. More recent outbreaks have altered thinking on the condition, previously seen as isolated to certain regions of the world. A 1993 outbreak in the Southwestern U.S. proved, however, that the condition is communicable in infinite geographical contexts and that it will take on various permutations as a function thereof. The condition is also typically fatal.

Pathogenesis:

To an extent, there remains some uncertainty concerning the pathogenesis of Hantavirus because it impacts human beings differently than it impacts its carrier. What has been ascertained with certainty about Hantarvirus is that it is almost universally transmitted from rodent to human with only rare instances in the case of specific strands revealing any transmission between human beings. According to the research conducted by Nichol et al. (1993), an outbreak of the virus in states in the Southwestern United States which brought new attention to the disease would also confirm the correlation between the pathogenesis of the condition in human beings and the presence of rodent carriers in the proximity of outbreaks. So denotes the research by Nichols et al., which reports on the specific outbreak that "A genetic detection assay amplified hantavirus-specific DNA fragments from RNA extracted from the tissues of patients and deer mice (Peromyscus maniculatus) caught at or near patient residences. Nucleotide sequence analysis revealed the associated virus to be a new hantavirus and provided a direct genetic link between infection in patients and rodents." (Nichol et al., 914)

This would also provide some insight into the systems which are attacked by the Hantavirus. The pathogenesis of the disease centers on a siege of the pulmonary system. According to Zaki et al. (1995), once again reporting on the Southwestern U.S. outbreak, indicated that "pulmonary histopathological features were similar in most of the fatal HPS cases (40/44) and consisted of an interstitial pneumonitis with a variable mononuclear cell infiltrate, edema, and focal hyaline membranes. In four cases, however, pulmonary features were significantly different and included diffuse alveolar damage and variable degrees of severe air space disorganization. IHC analysis showed widespread presence of hantaviral antigens in endothelial cells of the microvasculature, particularly in the lung. Hantaviral antigens were also observed within follicular dendritic cells, macrophages, and lymphocytes." (Zaki, 552)

In addition to pointing to the organ systems and receptors which are impacted by the Hantavirus, this denotes the condition to be largely fatal. This is an important feature which denotes that many fatal illnesses connected adult respiratory distress may be traceable to the presence of Hantavirus in the system and the physical environment in which the afflicted individual resides.

Transmission Signs:

With respect to identifying transmission signs, the emergence of a novel strand of the virus with the Southwestern U.S. outbreak of the early 1990s would demonstrate a challenge distinct to the Hantavirus. Namely, the condition appears to have fairly wide variance of incarnations which are distinct to regions, climates and species of rodent carrier. This makes identifying transmission signs difficult in individual cases, given that many of the symptoms in the early stages resemble those of the more common influenza spectrum of viral infections. As the text by Schmaljohn & Hjelle (1997) would report several years after this outbreak, "since the discovery of the HPS-causing hantaviruses, intense investigation of the ecology and epidemiology of hantaviruses has led to the discovery of many other novel hantaviruses. Their ubiquity and potential for causing severe human illness make these viruses an important public health concern." (Schmaljohn & Hjelle, 95)

This indicates that transmission signs will be centered not just on the observation of symptoms in an individual but on the patterns relating this condition to a specific geographical context. The Hantavirus will appear in clusters and will be traceable to specific living conditions that tend to incubate its presence. Namely, squalor and rodent infestation will be present in those contexts where Hantavirus is spread. This indicates that transmission signs should be identified from a combination of symptoms and living scenario.

Symptoms:

The symptoms of Hantavirus will undergo a set of phases with the increase in severity of the condition. Both in cases where the condition is fatal and in cases where convalescence does occur, the disease will take roughly a month to run its course. This course will include a transition from symptoms that resemble a strain of the influenza virus to more debilitating symptoms attacking lung, heart and kidney function. According to the research provided by Duchin et al. (1994), also offered in the wake of the Southwestern U.S. outbreak, "the most common prodromal symptoms were fever and myalgia (100%), cough or dyspnea (76%), gastrointestinal symptoms (76%), and headache (71%). The most common physical findings were tachypnea (100%), tachycardia (94%), and hypotension (50%)." (Duchin, 949) These findings would be gathered through autopsies of the first 17 victims of this outbreak, and demonstrated the condition to generally lead to 'rapidly progressive pulmonary edema.' (Duchin, 949)

Treatment:

Treatment remains the area of Hantavirus most in need of advancement. While our knowledge of the condition and its causes have improved, there yet remains a sharp gap between our ability to diagnose and our ability to treat this condition. The Centers for Disease Control (CDC) (2010) notes that while there is no specifically effective or known treatment for Hantavirus, "we do know that if infected individuals are recognized early and receive medical care in an intensive care unit, they may do better. In intensive care, patients are intubated and given oxygen therapy to help them through the period of severe respiratory distress." (CDC, 1)

In addition to this early-detection treatment courses which is recommended to ease pain and mitigate the high possibility of mortality, the most essential modes of treatment are prevention, identification and containment. An infectious disease which occurs in clusters but which is not generally transmitted by human interaction, Hantavirus can be contained when it is recognized. Therefore, the observation of transmission signs is important as a way of locating the threat and eliminating it through proper quarantine and rodent extermination. More importantly, education regarding sanitary living conditions and the expenditure of public resources to the elimination of community squalor or rodent infestation must be used as ways of reducing the threat of an essentially preventable disease with epidemic qualities.

Prognosis: