Group 6
Yanping Fan
Saray Felix
Chona Herella
1) Describe the pathogen that caused this disease.
Hantaviruses belong to the family of Bunyaviridae viruses. The Bunyaviridae family has 250 species in five genera: the bynyavirus, nairovirus, tospovirus, phlebovirus, and the hantavirus. These genera consist of arthropod- borne viruses, excluding hantavirus, which is a rodent-borne virus. Hantavirus was so named for the Hantan River in Korea, where it was first isolated during the Korean war in the early 1950’s. The
Korean Hantavirus disease was associated with hemorrhagic fever with renal syndrome
(HFRS). The Sin Nombre virus was recognized as a hantavirus species that caused
Hantavirus cardiopulmonary syndrome (HPS) and not HFRS. Sin Nombre virus was acknowledged after a 1993 breakout in New Mexico and other Four Corners states.
The Sin Nombre Hantavirus is classified as a group V in the Baltimore
Classification since it is a negative (-) sense single stranded RNA. Hantaviruses are enveloped with a genome composed of three RNA segments: S (small) genome that encodes for the nucleocapsid proteins, M (medium) genome encodes a co-translationally cleaved polyprotein that yields the envelope glycoproteins G1 and G2, and L (large) genome which encodes the L protein that functions as the viral transcriptase/ replicase.
Hantavirus glycoproteins interact with the cell receptors for mediated endocytosis. Replication occurs exclusively in the host cell cytoplasm after the nucleocapsids have been introduced into the cytoplasm. The virus enters the cell via a vacuole, which once in the cytoplasm, becomes protonated, thereby changing the pH and allowing the virions and genome to be released. Negative stranded RNA’s must package their genome with the replicase that synthesizes RNA’s. Hanta virus genome has no 5’ 7methyguanosine cap or 3’ poly-Adenylated tail since the genome will not serve as mRNA. Aside from serving as viral transcriptase and replicase, the L protein is also theorized to possess an endonuclease activity involved in “cap snatching”. The cellular mRNA is cleaved and used as a primer to initiate viral mRNA transcription.
Glycosylation is completed when the hetero- oligomers, formed from the glycoprotein components, are transported from the endoplasmic reticulum to the Golgi complex. Viral nucleocapsids associate with glycoproteins embedded in the Golgi complex membranes resulting in virus assembly. Assembled viruses then bud into the Golgi cisternae and are transported to the plasma membrane via secretory vesicles where viruses are released by exocytosis.
2) How would you diagnose this disease?
Hantavirus is indistinct, in comparison to other more prevalent diseases. As a result, it needs to be diagnosed with more than one test. Also, many of the underlying symptoms emulate ARDS symptoms, hence, it needs to be distinguished from it. The

patient is usually screened first to determine whether to test for Hantavirus of ARDS.
Many possible tests may be performed on patients demonstrating Hantavirus infection, and generally more than one is used to confirm the diagnosis. The following tests are more commonly performed: a) A Complete Blood Count - The test is performed to find out how many white blood cells you have. Your body produces more white blood cells when you have an infection, therefore it will show elevated white blood count. b) Platelet Count - will be less then 150,000 and decreasing when infected with a virus. c) X-ray of the chest - may show materials invading the chest cavity involving both lungs. d) Liver enzymes – LDH in patien will be elevated. LDH is a blood test that measures the amount of lactate dehydrogenase. e) Serum albumin - The serum albumin test measures the amount of albumin in serum, the clear liquid portion of blood. These levels will be decreased in an infected person. f) Hematocrit - will be increased, showing an increase in the levels of red blood cells. g) Serological testing for Hantavirus - Serology is a blood test to detect the presence of antibodies against a microorganism. If antibodies are detected, there has been exposure to an antigen. Detection of antibodies can be used to either diagnose an active or previous infection, or to determine if the individual is immune to re-infection by an organism.
3) How does Sin Nombre virus cause respiratory distress?
Hantavirus is aerolized and invades the respiratory system when inhaled. The actual mechanism of the Hantavirus still remains somewhat unclear. Once the virus has attacked the endothelial cells, the host’s immunological mechanism plays an important role in increasing the permeability of pulmonary capillaries and arteries of the host.
Therefore, allowing extravasations of fluid in the pleural cavity of the lungs causing shortness of breath.
Masuko and colleagues used Immunohistochemical techniques to detect the amounts of cytokine producing cells in the lungs. They discovered that there were increasing number of these cells in the lungs and spleen compared to the liver and the kidneys (1999). Another study by Kilpatrick et al , determined the significance of CD+8 T cells have increased with patients with HPS who needed mechanical ventilation compared to patients who did not.
There are worse case scenarios, such as Myocardial depression resulting in Sinus
Bradycardia (heart rate below 60 bpm), subsequent electrochemical dissociation (may not have pulse) and Ventricular tachycardia (increase in heart rate due to one of the ventricles). Fibrillation can also occur; the uncoordinated contraction of the heart is causing failure of blood to pump throughout the body. Once Fibrillation takes place, unconsciousness can occur for a couple of seconds, or even sudden death of the patient.
4) How is infection with this virus most commonly acquired?

The virus must be carried from the rodent to a person in order for Hantavirus to cause HPS. Infection of the virus is caused mainly by the deer mice which are found primarily in North America. To get this virus, one must be surrounded by desiccated feces, urine, saliva and other by-products that are aerosolized to the host (humans). The virus can actually survive in these dried by-products for weeks and in rare cases can last for months in areas with very low temperatures. Strangely one cannot be infected through human to human contact, only through the mice infected excreta. Studies have shown that other viruses from the same family can cause human-to-human infection.
5) How would you prevent an outbreak of this disease from occurring?
The best possible way to prevent an outbreak of Sin nombre virus from occurring is to eliminate or minimize rodent contact in the home, workplace, or campsite. There are many precautions that can be taken to minimize contact with rodents, as well as various methods for decontaminating infected items.
To minimize contact one would have to make sure that the home, shed, garage, basement, and other rooms or buildings not normally habituated are sealed up. Rodents enter the home through the smallest holes, therefore reducing their entryways will ensure that they do not nest in or near your home. Cleanliness is also important in preventing rodent contact. Setting traps in and around the home can also diminish the contact with rodents. The use of poisons of rodenticides can be used outdoors as a preventive measure, but keep in mind that they are toxic to pets and children. For this reason, encouraging the presence of rodent predators such as owls, hawks, and non- poisonous snakes seems like a more natural process.
It is important that precautions be taken when cleaning up or decontaminating infested areas so that infection does not occur. When undertaking the task of decontaminating an area one must make sure to wear the correct protective gear, like disposable coveralls, rubber boots, gloves, goggles, and appropriate respiratory masks, especially in an enclosed area where ventilation is not good quality. One must remember not to stir up dried by- products since this is the method employed by the virus to infect.
Rather, one would wet the contaminated area with detergent, 10% bleach, or disinfectant to deactivate the virus. The wet area is then cleaned with a damp towel (with disinfectant being used). The cleaned area is then mopped with a clean solution of disinfectant, detergent, or bleach.
If the infected items are delicate like books and papers decontamination is still possible. The delicate items can be placed outside in the sun or in a place with extreme heat for a week or longer, to deactivate the virus.
The waste materials from the decontamination process need to be disposed of appropriately by burning and/or burying. If the items cannot be burned or buried one can contact the local or state health department to dispose of the waste material.
The most important precaution that one can take is to not come into close contact with rodents, even if they do not show signs of infection. Through educating the population, especially in infected areas, HPS can be contained so that outbreaks are prevented.
6) What type of disease do other Hantaviruses usually cause?

Hantavirus Pulmonary Syndrome is the disease most common in the U.S. and
Western Hemisphere caused by different genus of the Hantavirus. However, other members of the Hantaviruse genus can cause different forms of Hemorrhagic Fever with
Renal Syndrome (HFRS), ususally encountered in Asia. The viral names given to some of the Hantavirus genus are representative of the place where it occurs: Hantaan virus,
Seoul virus, Puumala virus, and Dobrava virus.

Fabiano P. et al, (2007), Hantavirus Infection Induces a Typical Myocarditis That May
Be Responsible for Myocardial Depression and Shock in Hantavirus Pulmonary
Syndrome The Journal of Infectious Diseases, (195): pp 1541–1549.
Kilpatrick, E, (2004), Role of Specific CD8
+
T Cells in the Severity of a Fulminant
Zoonotic Viral Hemorrhagic Fever, Hantavirus Pulmonary Syndrome, The Journal of
Immunology, (172): 3297-3304.
Masuko Mori, et al, (1999) High Levels of Cytokine-Producing Cells in the Lung Tissues of Patients with Fatal Hantavirus Pulmonary Syndrome, The Journal of Infectious
Diseases, (179), pages 295–302 http://www.cdc.gov/ncidod/diseases/hanta/hps/noframes/FAQ.htm
Center for Disease and Control (CDC): National Center for Infectious Diseases- Special
Pathogens Branch
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