Monday, August 05, 2013

EID Journal: Novel Bunyavirus In Livestock - Minnesota


(Credit CDC)



# 7542


Bunyaviruses are an incredibly diverse family of negative stranded enveloped RNA viruses that are responsible for such dreaded diseases as Rift Valley Fever, Crimean - Congo Hemorrhagic Fever (CCHF), and Hantavirus.


While these viruses most commonly infect arthropods and rodents (and occasionally humans), curiously, one variety even infects plants - the (Tospovirsus) – and is responsible for tomato spotted wilt.


In the United States, probably the most common Bunyavirus infection reported is La Crosse (LAC) encephalitis, and less commonly Jamestown Canyon (JCV) and California encephalitis (CE). 


All three being mosquito vectored illnesses.


Over the past few years we’ve seen a new, often serious human infection emerge in Asia  - Severe Fever with Thrombocytopenia Syndrome (SFTS) - that produces a high fever, a low platelet count and and can lead to multiple organ failure.


SFTS first came to our attention in the spring and summer of 2009  after outbreaks were identified in China’s Hubei and Henan provinces.  While ticks were suspected as vectors, the pathogen behind this disease was not initially known.


In 2011, the NEJM published a study Fever with Thrombocytopenia Associated with a Novel Bunyavirus in ChinaSTFS has been associated with a 12% mortality rate in China.


Over the past year, we’ve seen reports of SFTS in Japan and Korea as well (see Japan Announces 4th SFTS FatalityKorean CDC On SFTS Cases).  Of note, we’ve also seen evidence of limited human-to-human transmission of this virus.


Person-to-person transmission of severe fever with thrombocytopenia syndrome virus.

Liu Y, Li Q, Hu W, Wu J, Wang Y, Mei L, Walker DH, Ren J, Wang Y, Yu XJ.


We concluded that SFTSV can be transmitted from person to person through contacting patient's blood.


Last year, in New Phlebovirus Discovered In Missouri we also learned of the discovery of another novel Bunyavirus – dubbed the Heartland Virus (HLV) - in two residents of Western Missouri. Last month CIDRAP NEWS reported that Researchers trace novel Heartland virus to Missouri ticks.


All of which serves as prelude to today’s report in the CDC’s EID Journal, where researchers in Minnesota conducted serological testing of domestic and captive farmed animals looking for evidence of SFTS and the Heartland virus.


What they found was an unexpectedly high prevalence (10%-18%) of antibodies (using an ELSIA reagent kit developed by China’s CDC) to SFTS in the cattle, goats, sheep, and elk they tested.   


Since the HLV and SFTF are antigenically cross reactive, the authors believe `the viruses detected in this region are most likely HLV or close relatives of HLV.’


The entire study is well worth reading, and is available at the link below.  I’ve excerpted the abstract and a small portion from the conclusion, as it speaks to the impact this discovery may have on public health.


Volume 19, Number 9—September 2013

Novel Bunyavirus in Domestic and Captive Farmed Animals, Minnesota, USA

Zheng XingComments to Author , Jeremy Schefers, Marc Schwabenlander, Yongjun Jiao, Mifang Liang, Xian Qi, Chuan Li, Sagar Goyal, Carol J. Cardona, Xiaodong Wu, Zerui Zhang, Dexin Li, James Collins, and Michael P. Murtaugh

We tested blood samples from domestic and captive farmed animals in Minnesota, USA, to determine exposure to severe fever with thrombocytopenia syndrome virus and Heartland-like virus. We found antibodies against virus nucleoproteins in 10%–18% of samples from cattle, sheep, goats, deer, and elk in 24 Minnesota counties.



Conclusion (EXCERPT)

Farmers, hunters, and persons with outdoor lifestyles may become infected when they are bitten by infected ticks. In addition, direct contact with secretions, body liquids, or feces from viremic animals would also put these persons and veterinarians at risk, if HLV- infected animals have substantial amounts of virus in blood and other tissues. The direct contact transmission of SFTSV has been reported in family clusters among persons with no history of tick bites, suggesting that person-to-person transmission may also occur (1315).


Evidence that a novel phlebovirus infects domesticated and captive farmed animals as shown in this study validates the concern that an SFTSV- or HLV-like emerging pathogen could pose a serious public health threat in the United States. Epidemiologic studies with a broader scope need to be conducted to elucidate viral ecology, and effective measures must be adopted to control this virus before it spreads among humans.




Although most people think first of Lyme disease when they get a tick bite, The CDC lists a growing number of diseases carried by ticks in the United States, including: Anaplasmosis, Babesiosis , Ehrlichiosis, Lyme disease, Rickettsia parkeri Rickettsiosis, Rocky Mountain Spotted Fever (RMSF), STARI (Southern Tick-Associated Rash Illness), Tickborne relapsing fever (TBRF), Tularemia, and 364D Rickettsiosis.

We’ve discussed a number these in the past, including:


Referral: Maryn McKenna On Babesia And The Blood Supply

NEJM: Emergence Of A New Bacterial Cause Of Ehrlichiosis

tick . . . tick . . . tick . . .

Minnesota: Powassan Virus Fatality


Given the smorgasbord of  of diseases carried by ticks it makes sense to avoid their bites whenever possibleThis advice from the Minnesota Department of Health.