Thursday, August 30, 2012

New Phlebovirus Discovered In Missouri

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(Credit CDC)

 

# 6525

 

 

As someone who contracted Lyme Disease 20 years ago, I’ve a deep and abiding interest in all manner of vector borne diseases. 

 

I’ve also developed an understandable revulsion to being around ticks . . . but that’s another matter.

 

 

The CDC lists a 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.

 

Today, we are learning of a new, novel virus detected in northern Missouri, again presumably carried by ticks. The lone star tick (Amblyomma americanum) is a prime suspect, but other ticks may carry it as well.

 

While there is a lot we don’t yet know, the following report appears today in the NEJM.

 

A New Phlebovirus Associated with Severe Febrile Illness in Missouri

Laura K. McMullan, Ph.D., Scott M. Folk, M.D., Aubree J. Kelly, M.S., Adam MacNeil, Ph.D., Cynthia S. Goldsmith, M.G.S., Maureen G. Metcalfe, B.S., Brigid C. Batten, M.P.H., César G. Albariño, Ph.D., Sherif R. Zaki, M.D., Ph.D., Pierre E. Rollin, M.D., William L. Nicholson, Ph.D., and Stuart T. Nichol, Ph.D.

N Engl J Med 2012; 367:834-841August 30, 2012

Two men from northwestern Missouri independently presented to a medical facility with fever, fatigue, diarrhea, thrombocytopenia, and leukopenia, and both had been bitten by ticks 5 to 7 days before the onset of illness. Ehrlichia chaffeensis was suspected as the causal agent but was not found on serologic analysis, polymerase-chain-reaction (PCR) assay, or cell culture.

 

Electron microscopy revealed viruses consistent with members of the Bunyaviridae family. Next-generation sequencing and phylogenetic analysis identified the viruses as novel members of the phlebovirus genus.

 

Although Koch's postulates have not been completely fulfilled, we believe that this phlebovirus, which is novel in the Americas, is the cause of this clinical syndrome.

 

Phlebovirus are part of the family Bunyaviridae, which includes such nasties as Crimean-Congo hemorrhagic fever, Hantaviruses, and Rift Valley Fever. There are more than 300 known Bunyaviruses.

 

Luckily for us, not all of them infect humans. 

 

Bunyaviruses  are mostly spread via arthropod vectors (ticks, mosquitoes & sand flies), with the exception of Hantaviruses (see Hantaviruses Revisited), which are spread via the feces and urine of rodents.

 

This particularly Phlebovirus is distinct from - but similar to - a new tickborne disease detected in China last year called the SFTS virus (see EID Journal  dispatch Severe Fever with Thrombocytopenia Syndrome Virus, Shandong Province, China Jun 2012).

 

Given that two cases showed up, hailing from 60 miles apart - and with no epidemiological links - it is likely that more cases will be found now that doctors know what to look for.

 

Dick Knox at NPR has a good report on what the CDC has dubbed `The Heartland Virus’, named after the Heartland Regional Medical Center in St. Joseph, Mo which alerted the CDC back in 2009 about these cases.

 

Mysterious New 'Heartland Virus' Discovered In Missouri

by Richard Knox

 

 

When you consider the wide panoply of  diseases carried by ticks - Lyme disease alone is considered responsible for 20,000+ infections each year (MMWR Lyme Disease --- United States, 2003—2005) it makes sense to avoid tick bites whenever possible.

 

This from the Minnesota Department of Health.

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Lastly, the CDC offers the following advice:

 

Preventing Tick Bites

While it is a good idea to take preventive measures against ticks year-round, be extra vigilant in warmer months (April-September) when ticks are most active.

Avoid Direct Contact with Ticks
  • Avoid wooded and bushy areas with high grass and leaf litter.
  • Walk in the center of trails.
Repel Ticks with DEET or Permethrin
  • Use repellents that contain 20% or more DEET (N, N-diethyl-m-toluamide) on the exposed skin for protection that lasts up to several hours. Always follow product instructions. Parents should apply this product to their children, avoiding hands, eyes, and mouth.
  • Use products that contain permethrin on clothing. Treat clothing and gear, such as boots, pants, socks and tents. It remains protective through several washings. Pre-treated clothing is available and remains protective for up to 70 washings.
  • Other repellents registered by the Environmental Protection Agency (EPA) may be found at http://cfpub.epa.gov/oppref/insect/.
Find and Remove Ticks from Your Body
  • Bathe or shower as soon as possible after coming indoors (preferably within two hours) to wash off and more easily find ticks that are crawling on you.
  • Conduct a full-body tick check using a hand-held or full-length mirror to view all parts of your body upon return from tick-infested areas. Parents should check their children for ticks under the arms, in and around the ears, inside the belly button, behind the knees, between the legs, around the waist, and especially in their hair.
  • Examine gear and pets. Ticks can ride into the home on clothing and pets, then attach to a person later, so carefully examine pets, coats, and day packs. Tumble clothes in a dryer on high heat for an hour to kill remaining ticks.

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