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We’ve a new report in Eurosurveillance on a recent spike in Hantavirus infections in Germany, and so today seems like a good day to discuss this little known pathogen.
`Hantavirus’ is a a collective term for a group of viruses –carried by various types of rodents - that vary in distribution, symptomology, and severity around the world.
While dozens of hantaviruses have been identified, not all cause disease in humans.
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.
The clinical symptoms of Hantavirus were first recognized by western medicine back in the early 1950s during the Korean war, when 3,000 UN troops stationed there were infected with a mysterious viral illness.
The mortality rate was 10%-15%, with patients experiencing fever, hypotension, renal failure, and internal bleeding (disseminated intravascular coagulation).
Originally called 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.
Scientists have since identified dozens of viruses within the genus Hantavirus (named after the Hantaan River of Korea) from all around the world.
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.
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, only about 500 cases of HCPS have been identified (across 33 states, but most occurring in the Southwest). Exposure to mice or rodents, and their droppings, has been established as the primary vector for this virus.
So, to sum up, Hantaviruses in Europe and Asia present with a Hemorrhagic Fever with Renal Syndrome, while in the Americas it is less common and generally (but not always)presents as a severe respiratory distress with cardiovascular shock.
This week, Eurosurveillance has a report on a steep rise in Hantavirus infections in Germany during the month of April.
The good news here is that the Hantavirus being reported here is the Puumala virus, which generally has the mildest symptoms and lowest mortality of the hantaviruses known to infect humans.
Eurosurveillance, Volume 15, Issue 20, 20 May 2010
Rapid communications
Steep rise in notified hantavirus infections in Germany, April 2010
Faber MS, Ulrich RG, Frank C, Brockmann SO, Pfaff GM, Jacob J, Krüger DH, Stark K. Steep rise in notified hantavirus infections in Germany, April 2010. Euro Surveill. 2010;15(20):pii=19574.
From January to April 2010, 396 hantavirus infections were notified in Germany, a considerable increase compared with previous years (mean: 83 for January–April 2004–2009) including the record-setting year, 2007 (n=232 January–April).
Most patients are residents of known Puumala virus endemic areas in southern Germany. The recent increase in notified hantavirus infections is probably due to an increased population density of the main animal reservoir, the bank vole (Myodes glareolus).
The chart below shows the yearly variability of reported Hantavirus infections in Germany, with 2007 having been a particularly active year.
Outbreaks of Puumala virus tend to spike every 3 or 4 years and farm workers, who are most likely to come in contact with the dust from Bank Vole droppings, are the most common victims.
The `New World’ versions of Hantavirus, including some that are found in South America, produces more severe disease. The CDC recently posted a short audio podcast on this rare, but often fatal, infection.
Of Mice and Man (A Cup of Health with CDC)
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.
Last December the MMWR published this account of 5 rare pediatric cases of HPS from four states during 2009.
Hantavirus Pulmonary Syndrome in Five Pediatric Patients --- Four States, 2009
Hantavirus pulmonary syndrome (HPS) is a reportable infectious disease with a high case-fatality rate, transmitted to humans by exposure to rodents.
Each year, 20--40 cases of HPS occur in the United States; cases in persons aged <17 years make up fewer than 7% of those cases, and cases in children aged <10 years are exceptionally rare.
CDC received reports of five pediatric cases of HPS occurring during May 16--November 25, 2009, among children aged 6--14 years from Arizona, California, Colorado, and Washington. Three of the children were aged <10 years, and all five had exposure to rodents.
The Special Pathogens Branch of the CDC has some information to help you prevent exposure and infection from hantaviruses on their Hantavirus Pulmonary Syndrome: What You Need To Know webpage.
The following is just an excerpt, follow the link to read the entire guide.
RESERVOIR
The deer mouse (Peromyscus maniculatus) is the primary reservoir of the hantavirus that causes hantavirus pulmonary syndrome (HPS) in the United States.
TRANSMISSION
Infected rodents shed the virus through urine, droppings, and saliva. HPS is transmitted to humans through a process called aerosolization. Aerosolization occurs when dried materials contaminated by rodent excreta or saliva are disturbed. Humans become infected by breathing in these infectious aerosols.
HPS in the United States cannot be transmitted from one person to another.
HPS in the United States is not known to be transmitted by farm animals, dogs, or cats or from rodents purchased from a pet store.
RISK
Anything that puts you in contact with fresh rodent urine, droppings, saliva or nesting materials can place you at risk for infection.
VIRUS
Hantaviruses have been shown to be viable in the environment for 2 to 3 days at normal room temperature. The ultraviolet rays in sunlight kill hantaviruses.
PREVENTION
Rodent control in and around the home remains the primary strategy for preventing hantavirus infection.
CLEANING
Use a bleach solution or household disinfectant to effectively deactivate hantaviruses when cleaning rodent infestations.
I’ve a keen personal interest in the Hantavirus because my ex-wife’s cousin (Ron Voorhees) was one of the original investigators in the famous 4 corner’s outbreak of Hantavirus in 1993 when he worked as an epidemiologist for the state of New Mexico.
It was during this outbreak that the New World `Sin Nombre’ (Spanish for `No Name’) Hantavirus was identified, and found to be widely prevalent in its natural host, the deer mouse.
If you would like to learn more about the history of that outbreak, and the epidemiological work done to identify the pathogen, I can direct you to an excellent account at:
Tracking a Mystery Disease:
The Detailed Story of Hantavirus Pulmonary Syndrome
