Tuesday, August 28, 2012

Hantaviruses Revisited

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Credit CDC

 

 

# 6522

 

While rare in the United States (see Hantavirus: An Emerging Infectious Disease), Hantavirus infections are back in the news today with the announcement of the second death this summer of a camper who had recently stayed at Yosemite National Park.

 

Hantavirus Kills Second Yosemite National Park Camper

 


In addition to these two fatal cases, two other non-fatal cases have been reported out of Yosemite Park this summer. The national park service issued the following press release yesterday:

 

Hantavirus Pulmonary Syndrome Response Continues at Yosemite National Park

 

Date: August 27, 2012

Park Takes Additional Steps to Protect Public Health

YOSEMITE NATIONAL PARK - The recent diagnosis of hantavirus pulmonary syndrome (HPS) in two Californians, one of whom died, has prompted Yosemite National Park to scale up its public health response and outreach. The National Park Service Office of Public Health learned over the weekend of a confirmed third case, which resulted in a fatality, and probable fourth case, of hantavirus in individuals who visited Yosemite National Park in June of this year.

 

An outreach effort is currently underway by the park concessioner to contact visitors who stayed in "Signature Tent Cabins" at Curry Village from mid-June through the end of August. These individuals are being informed of the recent cases and are being advised to seek immediate medical attention if they exhibit any symptoms of hantavirus.

(Continue . . . )

 

 

Until the early 1990s, few Americans had ever heard of Hantaviruses, even though the clinical symptoms of the infection were recognized by western medicine during the Korean war.

 

Roughly 3,000 UN troops stationed in Korea during the the early 1950s were infected with a mysterious viral illness. The mortality rate was 10%-15%, with patients experiencing fever, hypotension, renal failure, and internal bleeding called DIC (disseminated intravascular coagulation).

 

Originally dubbed Korean Hemorrhagic Fever, this condition is now known as Hemorrhagic Fever with Renal Syndrome (HFRS). Although it was suspected that rodents were the main epidemiological vector, the pathogen responsible wasn’t isolated until the 1970s.

 

Since then, scientists have identified dozens of viruses within the genus Hantavirus (named after the Hantaan River of Korea) from all around the world. 

 

In 1993, a major public health investigation was launched after a young Navajo man died suddenly from respiratory failure at a local hospital in New Mexico. It was subsequently discovered that his wife had passed away a few days earlier with the same symptoms.

 

After several months of investigation, additional cases were identified in the Four Corners region of the American southwest, and the `Sin Nombre’ (Spanish for `No Name’) Hantavirus was finally identified as the cause.

 

Investigators found it to be widely prevalent in its natural host, the deer mouse. For a detailed history of this epidemiological investigation you may wish to visit:

 

Tracking a Mystery Disease: The Detailed Story of Hantavirus Pulmonary Syndrome (HPS)

 

`Hantavirus is a collective term for a group of viruses carried by various types of  rodents - that vary in distribution, symptomology, and severity around the world. 

 

Like the majority of emerging infectious diseases, Hantavirus is a zoonotic disease; one that can be transmitted between (or are shared by) animals and humans.  

 

 

In Europe and Asia the hantavirus commonly presents as HFRS, and the mortality rate varies from 1% to 15% depending upon the specific hantavirus involved.  China reports the highest incidence of HFRS with between 20,000 – 100,000 cases each year.

 

Germany has recently experienced major epidemic outbreaks (2000+ cases/year) of the Puumala virus, which is carried by the bank vole (Myodes glareolus), which is widely distributed in Germany and across northern Europe.  

 

Fortunately, Puumala virus infection is rarely fatal (<1%) in humans (cite). The current edition of the CDC’s EID Journal  carries a report on this activity:

 

Multiple Synchronous Outbreaks of Puumala Virus, Germany, 2010

 

In the Americas, while infection is far less common, Hantavirus usually presents as Hantavirus Cardio-Pulmonary Syndrome (HCPS or sometimes just HPS), a more severe disease with a fatality rate of between 30% and 50%.

 

HCPS is marked by respiratory distress (ARDS) and cardiovascular collapse.

 

In the United States, fewer than 600 cases of HCPS have been identified over the past 19 years, most of which have occurred in the Southwest. Exposure to mice or rodents, and their droppings, has been established as the primary vector for this virus. 

 

While the odds of contracting Hantavirus are slim -given the high mortality rate - it is worth heeding the following advice from the CDC.

 

Preventing Hantavirus Pulmonary Syndrome (HPS)

Eliminate or minimize contact with rodents in your home, workplace, or campsite. If rodents don't find that where you are is a good place for them to be, then you're less likely to come into contact with them. Seal up holes and gaps in your home or garage. Place traps in and around your home to decrease rodent infestation. Clean up any easy-to-get food.

 

Recent research results show that many people who became ill with HPS developed the disease after having been in frequent contact with rodents and/or their droppings around a home or a workplace. On the other hand, many people who became ill reported that they had not seen rodents or rodent droppings at all. Therefore, if you live in an area where the carrier rodents are known to live, try to keep your home, vacation place, workplace, or campsite clean.

   

For more on all of this, the CDC has a number of resources, including podcasts and brochures,  available on Hantaviruses.

 

Podcasts

English

emerging infectious disease journal cover page

 Hantavirus Pulmonary Syndrome (July 2011)

speakerListen to this podcast (3:50)

Dr. Adam MacNeil, epidemiologist with Viral Special Pathogens Branch at CDC, discusses hantavirus pulmonary syndrome. Created: 7/14/2011 by National Center for Emerging Zoonotic and Infectious Diseases (NCEZID). Date Released: 7/18/2011.

A Cup of Health with CDC logo Of Mice and Man (January 2010)

speakerListen to this podcast: Long version (4:38) or Short version (0:59)

Hantavirus Pulmonary Syndrome, or HPS, is a disease that is caused by people coming in contact with rodents. HPS is caught when dirt or dust containing rodent excretion or other bodily fluids is stirred up and breathed in or absorbed through broken skin. The result is a serious condition in which one of three reported cases has been fatal. In this podcast, Dr. Barbara Knust discusses HPS. Created: 1/14/2010 by MMWR. Date Released: 1/14/2010.

Spanish

A Cup of Health with CDC logo Cuando entran los ratones

speakerListen to this podcast (1:21)

El síndrome pulmonar por hantavirus o SPH es causado por virus presentes en las excreciones u otros líquidos corporales de los roedores que pueden introducirse al cuerpo humano por la respiración o a través de la piel abierta. El resultado es una enfermedad grave en la cual uno de tres casos reportados suele ser mortal. Este podcast indica los signos y síntomas iniciales del síndrome pulmonar por hantavirus y da consejos sobre qué hacer para evitar la exposición. Created: 1/14/2010 by MMWR. Date Released: 3/15/2011.

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