Minnesota Reports Swine H1N2v Flu

 

 

# 6530

 

File this under - `Once you start looking, no telling what you’ll find’.

 

Enhanced surveillance for H3N2v flu cases associated with contact with pigs by Minnesota’s Department of Health has turned up 1 confirmed, and 2 probable human cases of H1N2v influenza.

 

The H1N2 virus is one of three flu strains that commonly circulate in swine (H1N1, H3N2, & H1N2).

 

H1N2 is assumed to be a reassortment between the H1N1 and H3N2 virus. It has on rare occasions been detected in humans. 

 

Credit CDC

 

Minnesota reported a human infection with A/H1N2 in December of 2011, and it was said to be similar to an H1N1 virus (A/New Caledonia /20/99-like) that circulated as recently as 2007. 

 

Michigan reported an H1N2 human infection in 2007. 

 

As has been pointed out in this blog before, we honestly don’t know how often these novel swine (or avian)origin flu viruses jump to humans. Given the limits of testing and surveillance, it is probably more common than the numbers suggest.

 

Heightened surveillance around the country for the H3N2v virus may very well tell us a good deal about other variant viruses that we know can occasionally show up in the human population.

 

 

Here is the Press release from the MDH.

 

 

News Release
August 31, 2012
 

Three human cases of influenza linked to swine exposure at State Fair

Strain is different from the one that prompted current surveillance and prevention efforts

Three people are believed to have developed a strain of influenza known as variant H1N2 (H1N2v) after exhibiting pigs or spending time in the swine barn at the Minnesota State Fair.

 

One of the three cases has been confirmed by CDC. Test results for the other two are pending.

 

The H1N2v strain is different from the H3N2v strain that has prompted stepped up surveillance and prevention efforts nationwide, after causing 289 reported cases of illness and one death since the beginning of the year.

 

Officials at the Minnesota Department of Health (MDH) say they are not currently aware of any additional human influenza cases caused by H1N2v, and they do not anticipate changing their current public health recommendations regarding human exposure to swine.

 

They emphasized, however, that they will continue to assess the situation and conduct aggressive surveillance for additional influenza cases.

 

Current recommendations include asking individuals at high risk for severe influenza to avoid swine contact at exhibitions, fairs, live markets and other venues, including the swine barn at the State Fair. High risk individuals include children under five years of age, pregnant women, people 65 years of age or older and those with chronic medical conditions.

 

"For the past two weeks, we have been looking very hard for cases of influenza in people who have been exposed to swine," said Richard Danila, Deputy State Epidemiologist. "We have also worked closely with our veterinary colleagues to remain informed about potential infections in swine at the Fair. It is because of this careful surveillance that these cases have come to our attention.

 

"Right now, we don’t have any basis for changing our recommendations to the public," Danila said.

 

The illness has been confirmed in a teenage girl who was exhibiting pigs at the fair and became ill on Aug. 26. The other two cases occurred in an elementary-school-aged boy who became ill on Aug. 27 after spending all day in the swine barn on Aug. 24, and a woman in her late seventies who became ill on Aug. 26 after spending a prolonged period of time in the swine barn and at the swine show in the Exhibit Hall on Aug 24.

 

Both the boy and the older woman had underlying health conditions, and were treated with antiviral drugs. The woman was hospitalized, but has now been released. All three patients have recovered or are recovering.

 

The teenager was tested for influenza after she reported illness to nursing staff at the Fair. The other cases were reported to MDH by health care providers. Health care providers have been asked to report cases of influenza-like illness in people who report that they have had contact with swine. Swine exhibitors have been asked to report it if they experience symptoms of influenza.

 

Fair officials have also been monitoring swine for possible symptoms of illness, so they can be tested. Two pigs at the swine exhibit were found to be infected with the same H1N2 virus earlier this week, and were both isolated from contact with other pigs. Infection with H1N2 is not considered unusual in pigs.

-MDH-

 

 

For more on the H1N2 virus, you may wish to revisit:

Hong Kong Swine Influenza Surveillance

CDC: Variant Influenza Strains

CDC Confirms 2 More Novel Flu Infections

If You’ve Seen One Triple Reassortant Swine Flu Virus . . .

CDC Updates H3N2v Numbers, 1 Death Reported

# 6529

 

 

The CDC has posted their weekly update on the emerging H2N2v (variant) flu virus, and there’s good news and sad news:

 

The good news is that only a dozen additional cases have been confirmed, and no additional states have reported infections. It is highly likely, however, that some number of cases are going unreported.

 

That said, were this virus spreading in an efficient and sustained manner in the human population, we would expect to see a lot more cases being reported. 

 

 

The sad news – not unexpectedly – is that a death has finally been attributed to this variant virus.

 

This was pretty much Inevitable, given that this virus has been described as being roughly equivalent in virulence to seasonal flu, which claims thousands of lives each year.

 

 

The CDC reports:

 

Influenza A (H3N2) Variant Virus Outbreaks

Today, CDC is reporting 12 additional cases of H3N2 variant virus (H3N2v) infection, as well as the first H3N2v-associated death, which was reported by the state of Ohio. The death occurred in an older adult with multiple underlying health conditions who reportedly had direct exposure to pigs in a fair setting.

 

While limited person-to-person spread of this virus has been detected and likely continues to occur sporadically, no sustained community transmission has been found. CDC is monitoring this situation and working with states to respond to these evolving outbreaks. The agency continues to urge people at high risk from serious flu complications to stay away from pigs and pig arenas at fairs this summer.

 

<SNIP>

 

The 12 new cases reported this week are from the states of Minnesota (1), Ohio (3), Pennsylvania (1), and Wisconsin (7). Cumulative totals for 2011 and 2012 by state are available in the H3N2v case count table.

(Continue . . . .)

 

Graphs from today’s FluView report also illustrate the drop in new cases, and provides some detail on the level of H3N2v activity.

 

2011-2012 Influenza Season Week 34 ending August 25, 2012

All data are preliminary and may change as more reports are received.

U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories located in all 50 states and Washington, D.C. report to CDC the number of respiratory specimens tested for influenza and the number positive by influenza type and subtype. Region specific data can be found at http://gis.cdc.gov/grasp/fluview/fluportaldashboard.html.

Novel Influenza A Virus:

From July 12 through August 30, 2012, a total of 288 infections with influenza A (H3N2) variant (H3N2v) viruses have been reported in ten states (Hawaii [1], Illinois [4], Indiana [138], Maryland [12], Michigan [5], Minnesota [2], Ohio [101], Pennsylvania [7], West Virginia [3], and Wisconsin [15]). So far during the current outbreaks, 15 confirmed cases have been hospitalized as a result of their illness; one death has occurred.

 

The vast majority of cases have been associated with swine exposure though likely instances of human-to-human transmission have been identified. At this time no ongoing human-to-human transmission has been identified.

 

Public health and agriculture officials are investigating the extent of disease among humans and swine, and additional cases are likely to be identified as the investigation continues. Because of reporting deadlines, the state totals reported by CDC may not always be consistent with those reported by state health departments. If there is a discrepancy between these two counts, data from the state health departments should be used as the most accurate number.

 

 

The concern here is less about the public health threat this variant virus poses today - and more about the threat it could pose in the future - if it better adapts to transmit between humans.

 

Each human infection, unfortunately, gives the virus another opportunity to adapt, making prevention of infection all the more important.

 

Meanwhile, we continue to watch these weekly tally’s with considerable interest, looking for any indications that something has changed.

Hawaii & Japan Tsunami Advisories

 

**** UPDATE:  USGS lowers Magnitude to 7.6 ****

**** UPDATE: Tsunami Watch For Hawaii Cancelled ****

BULLETIN
TSUNAMI MESSAGE NUMBER   2
NWS PACIFIC TSUNAMI WARNING CENTER EWA BEACH HI
331 AM HST FRI AUG 31 2012

TO - CIVIL DEFENSE IN THE STATE OF HAWAII

SUBJECT - TSUNAMI WATCH CANCELLATION

THE EARTHQUAKE MAGNITUDE IS REDUCED.

THE TSUNAMI WATCH IS CANCELLED FOR THE STATE OF HAWAII EFFECTIVE
AT 0331 AM HST.

USGS Shake map

 

# 6528

 

Although it is not yet known whether a tsunami was generated by the 7.9 earthquake that occurred within the last hour east of the Philippines, Japan has issued a tsunami advisory, and Hawaii is under a tsunami watch.

 

This from the Pacific Tsunami Warning Center.

 

TO - CIVIL DEFENSE IN THE STATE OF HAWAII

SUBJECT - TSUNAMI WATCH

A TSUNAMI WATCH IS ISSUED FOR THE STATE OF HAWAII EFFECTIVE AT 0257 AM HST.

AN EARTHQUAKE HAS OCCURRED WITH THESE PRELIMINARY PARAMETERS

   ORIGIN TIME - 0248 AM HST 31 AUG 2012
   COORDINATES - 10.9 NORTH  127.1 EAST
   LOCATION    - PHILIPPINE ISLANDS REGION
   MAGNITUDE   - 7.9  MOMENT

EVALUATION

BASED ON ALL AVAILABLE DATA A TSUNAMI MAY HAVE BEEN GENERATED BY THIS EARTHQUAKE THAT COULD BE DESTRUCTIVE ON COASTAL AREAS EVEN
FAR FROM THE EPICENTER. AN INVESTIGATION IS UNDERWAY TO DETERMINE IF THERE IS A TSUNAMI THREAT TO HAWAII.

IF TSUNAMI WAVES IMPACT HAWAII THE ESTIMATED EARLIEST ARRIVAL OF THE FIRST TSUNAMI WAVE IS

                     1228 PM HST FRI 31 AUG 2012

MESSAGES WILL BE ISSUED HOURLY OR SOONER AS CONDITIONS WARRANT

 

 

Meanwhile, Japan’s Meteorological Agency has issued a Tsunami advisory for what may be a .5 meter tidal wave.

**********About Tsunami Forecast************
<Tsunami Advisory>
Tsunami height is expected to be about 0.5 meters. Attention advised.

******* Earthquake Information ********

Occurred at 
21:48 JST 31 Aug 2012

Region name 
PHILIPPINES AND ITS VICINITY

Latitude 10.9N

Longitude 127.1E

Depth Unknown

Magnitude  7.9

 

UPDATE:  No Destructive Tsunami Expected Along West Coast

 

To: U.S. West Coast, Alaska, and British Columbia coastal regions

From: NOAA/NWS/West Coast and Alaska Tsunami Warning Center

Subject: Tsunami Information Statement #2 issued 08/31/2012 at 6:36AM PDT

This message is updated with REVISED MAGNITUDE OF 7.6.

A strong earthquake has occurred, but a tsunami IS NOT expected along the California, Oregon, Washington, British Columbia, or Alaska coast. NO tsunami warning, watch or advisory is in effect for these areas.

A damaging tsunami IS NOT expected along the California, Oregon, Washington, British Columbia, and Alaska coasts although some of these areas may experience non-damaging sea level changes.

At 5:48 AM Pacific Daylight Time on August 31, an earthquake with preliminary magnitude 7.6 occurred in the Philippine Islands region . (Refer to the United States Geological Survey for official earthquake parameters.)

Pacific coastal regions outside California, Oregon, Washington, British Columbia, and Alaska should refer to the Pacific Tsunami Warning Center messages for information on the event.

This will be the final statement issued for this event by the West Coast/Alaska Tsunami Warning Center unless conditions warrant. See the WCATWC web site for basic tsunami information, safety rules, and a tsunami travel time map. (NOTE: Travel time maps indicate forecasted times only, not that a wave was generated.)

Philippines: 7.9 Quake & Tsunami Warning

****  UPDATE:  USGS lowers Magnitude to 7.6 ****

**** UPDATE: Tsunami Watch For Hawaii Cancelled ****

USGS Earthquake Map

 

# 6527

 

Preliminary reports indicate that a 7.9 magnitude quake has struck east of the Philippines, and a Tsunami warning and watch have been issued by the Pacific Tsunami Warning Center.

 

TSUNAMI BULLETIN NUMBER 001

PACIFIC TSUNAMI WARNING CENTER/NOAA/NWS
ISSUED AT 1255Z 31 AUG 2012

THIS BULLETIN APPLIES TO AREAS WITHIN AND BORDERING THE PACIFIC OCEAN AND ADJACENT SEAS...EXCEPT ALASKA...BRITISH COLUMBIA...
WASHINGTON...OREGON AND CALIFORNIA.

... A TSUNAMI WARNING AND WATCH ARE IN EFFECT ...

A TSUNAMI WARNING IS IN EFFECT FOR   INDONESIA / PHILIPPINES / BELAU / YAP / TAIWAN / JAPAN / GUAM / N. MARIANAS / PAPUA NEW GUINEA

A TSUNAMI WATCH IS IN EFFECT FOR   CHUUK / MARCUS IS. / KOSRAE / POHNPEI / MARSHALL IS. /
WAKE IS. / SOLOMON IS. / RUSSIA / NAURU

FOR ALL OTHER AREAS COVERED BY THIS BULLETIN... IT IS FOR INFORMATION ONLY AT THIS TIME.

 

 

At this time, we’ve no reports of damage, and we do not know whether a tsunami was generated, only that one is possible.

 

Yosemite Hantavirus Cases Increase To Six

Yosemite National Park, California, USA Credit CDC

 

# 6526

 

Overnight we’ve news that two more cases of Hantavirus infection have been detected among recent visitors to Yosemite National Park in California, bringing the total now to six, with two fatalities.

 

The following press release, from the California Department of Public Health, mentions four new cases, but two of those were previously announced (see Hantaviruses Revisited for earlier reports and background on the virus).

 

 

Hantavirus Found in Four More Visitors to Yosemite National Park

Date: 8/30/2012

Number: 12-049

Contact: Anita Gore or Heather Bourbeau - (916) 440-7259

SACRAMENTO

The California Department of Public Health (CDPH) today reported four additional cases of Hantavirus Pulmonary Syndrome (HPS), bringing the total number of people infected with the hantavirus who visited Yosemite National Park to six.

 

“CDPH is working closely with the National Park Service and the Centers for Disease Control and Prevention to further investigate the cluster of Hantavirus Pulmonary Syndrome cases in Yosemite and reduce the risk of other visitors becoming ill from this virus,” said CDPH Director, Dr. Ron Chapman. “CDPH is continuing to monitor cases of Hantavirus Pulmonary Syndrome in persons who visited Yosemite National Park.”

 

To date, HPS has been confirmed in six persons who visited the park between early June and mid July 2012. Five are California residents and one is a resident of Pennsylvania. The PA patient and one CA patient have died, three have recovered and one is currently hospitalized but improving. Four, including both fatalities, lodged in the “signature cabins” of the Boystown area of Curry Village, one lodged in an unspecified area of Curry Village, and one is still under investigation.

 

The six individuals infected are residents from the Sacramento region, San Francisco Bay area, Southern California and one from Pennsylvania.

 

On August 28, per recommendations from CDPH, Yosemite National Park closed all tent cabins in the Boystown area indefinitely. The National Park Service has issued communications to guests who had stayed in the Boystown area between June 10 and August 24, alerting them to the HPS concerns and recommending that they seek medical attention if ill.

(Continue . . .)

As the epidemiological investigation and search for additional cases continues, a number of local media outlets are reporting that warnings from the state urging that park officials educate campers about the risks from the Hantavirus were not acted upon.

 

 

State had warned Yosemite about hantavirus

Christina Jewett, California Watch

Updated 11:07 p.m., Thursday, August 30, 2012

State public health scientists have recommended twice in the past five years that Yosemite National Park authorities educate visitors about hantavirus, a rare disease linked to the deaths of two park visitors this summer - but park officials did not warn tourists until after the disease showed up in recent weeks.

(Continue . . . )

 

 

An AP report by Joseph Dearen (see 2 more Yosemite visitors have mouse-borne virus) outlines steps taken by the park service last spring to reduce the threat from Hantavirus after 18% of mice trapped and tested around the park tested positive for the virus.

 

According to a number of sources, roughly 20% of deer mice routinely carry the virus, making the survey numbers at Yosemite about average.

 

The State of California maintains a FAQ on Hantaviruses, from which the following is excerpted:

 

How are hantaviruses maintained in nature?

Hantaviruses are maintained in nature in wild rodents. In California, only deer mice carry and shed SNV. Other rodents such as squirrels, chipmunks, and house mice are rarely, if ever, infected and do not pose a risk of HCPS to humans.

How do you get HCPS?

Infected rodents shed hantavirus in their urine, droppings, and saliva. Most HCPS patients become infected by breathing air contaminated with rodent urine or droppings, such as when cleaning out a rodent-infested space. This most commonly occurs in small, confined spaces where there is little air circulation. Rarely, individuals can also be infected by:

1) consuming food contaminated with rodent urine or droppings;

2) touching surfaces where rodents have been, and then putting their hand in their mouth;

3) being bitten by an infected rodent.

 

Meanwhile the CDC has updated their Hantavirus web pages in response to this outbreak:

 

Signs & Symptoms for Hantavirus Pulmonary Syndrome (HPS)

Due to the small number of HPS cases, the "incubation time" is not positively known. However, on the basis of limited information, it appears that symptoms may develop between 1 and 5 weeks after exposure to fresh urine, droppings, or saliva of infected rodents.

Early Symptoms

Early symptoms include fatigue, fever and muscle aches, especially in the large muscle groups—thighs, hips, back, and sometimes shoulders. These symptoms are universal.

 

There may also be headaches, dizziness, chills, and abdominal problems, such as nausea, vomiting, diarrhea, and abdominal pain. About half of all HPS patients experience these symptoms.

Late Symptoms

Four to 10 days after the initial phase of illness, the late symptoms of HPS appear. These include coughing and shortness of breath, with the sensation of, as one survivor put it, a "...tight band around my chest and a pillow over my face" as the lungs fill with fluid.

Is the Disease Fatal?

Yes. HPS can be fatal. It has a mortality rate of 38%.

 

 

And answers to two very common questions about this disease can be found on the CDC’s Hantavirus Transmission page (emphasis mine).

 

The types of hantavirus that cause HPS in the United States cannot be transmitted from one person to another. For example, you cannot get the virus from touching or kissing a person who has HPS or from a health care worker who has treated someone with the disease. You also cannot get the virus from a blood transfusion in which the blood came from a person who became ill with HPS and survived.

Can pets transmit HPS to humans?

The hantaviruses that cause HPS in the United States are not known to be transmitted by any types of animals other than certain species of rodents. Dogs and cats are not known to carry hantavirus; however, they may bring infected rodents into contact with people if they catch such animals and carry them home. Guinea pigs, hamsters, gerbils, and rodents from pet stores are not known to carry hantavirus.

 

 

You’ll find details on investigation into the Yosemite outbreak at:

 

August 2012 - Yosemite National Park Outbreak Notice

Updated: August 29, 2012

 

On August 27, 2012, The National Park Service (NPS) announced that there were 3 confirmed cases and 1 probable case of Hantavirus Pulmonary Syndrome (HPS) in visitors who stayed at Curry Village in Yosemite National Park since June of this year. Public health officials believe that these visitors may have been exposed to Hantavirus while staying at the Signature Tent Cabins in Curry Village. Two people have died. CDC and the California Department of Public Health (CDPH) are working with the National Park Service in responding to the situation.

 

The park is contacting visitors who stayed in the Signature Tent Cabins from mid-June through the end of August, advising them to seek immediate medical attention if they exhibit symptoms of HPS. Hantavirus is a rare but serious disease and confirmed cases should be reported to CDC via state health departments

(Continue . . .)

 

 

And a final note, while hantavirus outbreaks garner a lot of headlines, human infection with this virus is exceedingly rare in the United States. 

 

Fewer than 600 cases have been registered since the early 1990s.

 

With roughly 4 million visitors to Yosemite National Park each year, and only six cases so far, the absolute risk of contracting this virus while camping there is extremely low.

New Phlebovirus Discovered In Missouri

(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.

 

 

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.

Pre-Symptomatic Transmission Of H1N1 Influenza In the Ferret Model

Not the only way to spread the Flu - Photo Credit PHIL

 

# 6524

 

There are a lot of things we think we know about influenza transmission, but for which we have limited physical proof. Sometimes, the evidence we do have is conflicting, or less than conclusive.

 

Which helps explains why we continue to see debate and controversy over the value of many protective measures, like hand washing, the wearing of masks, school closures, and screening airline passengers during a pandemic.

 

One of the assumptions has been that under certain circumstances it may be possible for an infected host to transmit the flu virus before their symptoms appear.

 

Last year in EID Journal: Pre-Symptomatic Influenza Transmission, we looked at research out of Japan which found evidence suggesting transmission of the 2009 H1N1 virus during a carrier’s presymptomatic phase.

 

If presymptomatic and asymptomatic carriers of a flu virus are capable of efficiently transmitting the illness on to others, then strategies that seek to identify and isolate symptomatic cases would have only limited success in containing a pandemic.

 

And we saw indications of these limitations during the 2009 pandemic when nations like Japan, India, and China attempted to identify and isolate those who might be carrying the H1N1 virus as they entered the country.

 

While their efforts may have slowed the introduction of the virus, they certainly didn’t stop it.  Earlier blogs on these attempts include:

 

Japan: Quarantine At Ports Ineffective Against Pandemic Flu

Experts: Extreme Measures Won’t Stop The Flu

 

The assumption is their failure was probably due to the large number of presymptomatic, and asymptomatic carriers of the virus that arrived without showing signs of illness.

 

All of which serves as prologue to a study, which appeared yesterday in PLoS One, that tests the hypothesis of presymptomatic transmission of the 2009 H1N1 virus using ferrets.

 

Transmission of a 2009 H1N1 Pandemic Influenza Virus Occurs before Fever Is Detected, in the Ferret Model

Kim L. Roberts, Holly Shelton, Peter Stilwell, Wendy S. Barclay

ABSTRACT (excerpt)

We found that pre-symptomatic influenza transmission occurred via both contact and respiratory droplet exposure before the earliest clinical sign, fever, developed.

 

Three of 3 animals exposed in direct contact between day 1 and 2 after infection of the donor animals became infected, and 2/3 of the animals exposed at this time period by the RD route acquired the infection, with the third animal becoming seropositive indicating either a low level infection or significant exposure.

 

Moreover, this efficient transmission did not temporally correlate with respiratory symptoms, such as coughs and sneezes, but rather with the peak viral titre in the nose. Indeed respiratory droplet transmission did not occur late in infection, even though this was when sneezing and coughing were most apparent.

 

None of the 3 animals exposed at this time by the RD route became infected and these animals remained seronegative at the end of the experiment. These data have important implications for pandemic planning strategies and suggest that successful containment is highly unlikely for a human-adapted influenza virus that transmits efficiently within a population.

 

 

Essentially, researchers inoculated ferrets with the 2009 H1N1 flu, and then placed them near uninfected ferrets (some in direct contact, others in adjacent cages) at different stages after infection.

 

They then tested the exposed ferrets to see when, and under what circumstances, they became infected. They found that ferrets became infectious just 24 hours after becoming infected, and nearly 24 hours before showing the earliest outward signs of infection (fever).

 

Since limited presymptomatic transmission of influenza has long been suspected, the big surprise here wasn’t confirming that it can occur, but rather, how robust this form of transmission turned out to be.

 

Influenza is believed to be transmitted via large droplets – usually expelled by coughing and sneezing - along with smaller aerosolized virus particles, plus contaminated surfaces (fomites) where airborne droplets may land or we may otherwise touch and contaminate.

 

Today’s study strongly suggests (with ferrets, anyway) that simply breathing in and out can shed sufficient flu virus into the air to spread to others, without the added `boost’ provided by coughs and sneezes.

 

Indeed, the only transmission these researchers observed occurred early in the infection, before the symptoms of coughing and sneezing appeared.

 

This suggests that those who may be symptomatic, but 5 or 6 days into their illness, may be far less likely to transmit the virus to others. 

 

The caveats with this research include that this study was conducted on ferrets, not humans, and with a single flu strain. Other experiments have shown variations in transmission traits depending on the strain tested.

 

As I wrote in They Walk Among Us, back during the pandemic in 2009:

 

Like it or not, there is no easy litmus test for infection (and viral shedding) when it comes to influenza.   The array of symptoms (or lack thereof) displayed by those infected with the H1N1 virus preclude any kind of 100% accurate `checklist for infection’.

 

Sure, we could lock up everyone who sneezes, coughs, or spikes a fever for 2-weeks.  But even that wouldn’t catch those who are shedding the virus before developing symptoms, or those who remain asymptomatic for the full course of their illness.

 

While the advice to `stay home if you are sick’ remains valid, the truth is, you don’t have to be visibly ill in order to pass the flu virus on to others.

 

These findings will likely fuel the debate over the need for Health Care Workers -- and others who have direct contact with vulnerable populations - to get the annual flu vaccination. 

 

If we can be infectious without knowing it, then we cannot simply say we will stay home or wear a mask when we are sick, in order to protect others.

 

For more on asymptomatic respiratory illnesses, you may wish to revisit:

 

The Very Common Cold

EID Journal: Airport Screening For Pandemic Flu In New Zealand

PLoS One: H1N1 Seroprevalence Study

ICEID: Asymptomatic H1N1 in HCWs

Today’s CDC West Nile Update

 

 

# 6523

 

For the second week in a row the CDC, in conjunction with the Texas Department of State Health Services, today presented an extended teleconference on this year’s record setting West Nile Virus epidemic. 

 

While the totals are constantly changing, the DVBID has updated the nation’s numbers as reported to ArboNet as of yesterday. Of concern, the number of neuroinvasive cases is the highest that’s ever been reported through the end of August.

 

Forty-three states are reporting human infections, and only Hawaii and Alaska have not reported detecting the virus in humans, birds, or mosquitoes.

 

So far in 2012 there have been 1590 human infections reported, 889 of which were of the more severe, neuroinvasive type.  In addition, 66 deaths have been reported.

 

Texas, which has been particularly hard hit this year, has reported 31 deaths, and 416 neuroinvasive cases. 

 

Neuroinvasive cases (which present with meningitis, encephalitis, or flaccid Paralysis) are severe enough that they result in hospitalization and diagnosis, and so they are considered a better indicator of the scope of each year’s epidemic.

 

Mild cases – called West Nile Fever – often go undiagnosed, with probably only 2%-3% being identified.

 

In terms of impact, based on incidence per 100,000 population, 6 states - Texas, Oklahoma, South Dakota, Louisiana and Mississippi – have been hardest hit.

 

 

Given the incubation period of 10-14 days, and delays in diagnosis and reporting, human case counts are considered lagging indicators. Even though transmission generally peaks in mid to late August, it may be late September or early October before we start to see a noticeable decline in numbers.

 

For reasons that are complex, and not completely understood, the rate of transmission of the WNV virus to humans varies widely from place to place, and from one year to the next. 

 

Last year was a relatively quiescent year for the West Nile virus, with just 712 cases reported, along with 43 deaths. In comparison, in 2003 more than 4,150 cases were reported, with 284 fatalities.

 

 

While some have expressed concerns over the heavy rains associated with hurricane Isaac, the CDC is not expecting them to greatly exacerbate the transmission of the virus.

 

A transcript, and an audio recording of today’s 50 minute teleconference should be available later today at http://www.cdc.gov/media/index.html

 

The bottom line is that the West Nile Virus is now endemic across most of the United States, and while the absolute risk of infection in many places may be low, the prudent move is to take the recommended precautions against mosquito bites.

 

 

 

And finally, to find out about the West Nile threat in your area, you can visit the DVBID website below:

Links to State and Local Government West Nile Virus Web Sites

Click on a state to link directly to their West Nile virus Web page.

 

See list below for additional city-level and main State Health Department Web sites.

Study: Kids, Underlying Conditions, And The 2009 Pandemic Flu

Credit CDC FluView

 

# 6522

 

The chart above illustrates the sharp rise in pediatric deaths from flu-related complications during the 2009-2010 H1N1 pandemic seasons in the United States.  As grim as this charts is, it probably doesn’t fully represent the burden the 2009 pandemic placed on the pediatric community.

 

In another chart, again from the CDC, we get an estimate of deaths related to the 2009 pandemic, broken down by age groups through April of 2010.

 

 

While just over 300 pediatric deaths were recorded during this time period, the CDC estimates that 4 times (n=1280) that many children likely died from flu-related illness in the United States.

 

Globally, the number was undoubtedly many times higher than that (see Lancet: Estimating Global 2009 Pandemic Mortality).

 

 

All of which serves as prelude to a new study that appears today in the journal  Pediatrics, that looks at 336 documented pH1N1-associated deaths, and finds a high number of kids with underlying neurologic conditions.

 

Two-thirds of all deaths in children under the age of 17 occurred in kids with at least 1 underlying medical condition (n=227), and just under half of all cases (n=146) involved neurological disorders, such as cerebral palsy, epilepsy, or intellectual disability.

 

 

Neurologic Disorders Among Pediatric Deaths Associated With the 2009 Pandemic Influenza

Lenee Blanton, MPH^a,Georgina Peacock, MD, MPH, FAAP^b, Chad Cox, MD, MPH^a, Michael Jhung, MD, MPH^a, Lyn Finelli, DrPH^a, and Cynthia Moore, MD, PhD^b

ABSTRACT (Excerpts)

RESULTS: Of 336 pH1N1-associated pediatric deaths with information on underlying conditions, 227 (68%) children had at least 1 underlying condition that conferred an increased risk of complications of influenza. Neurologic disorders were most frequently reported (146 of 227 [64%]), and, of those disorders, neurodevelopmental disorders such as cerebral palsy and intellectual disability were most common.

CONCLUSIONS: Neurologic disorders were reported in nearly two-thirds of pH1N1-associated pediatric deaths with an underlying medical condition. Because of the potential for severe outcomes, children with underlying neurologic disorders should receive influenza vaccine and be treated early and aggressively if they develop influenza-like illness.

 

According to a statement released last night by the CDC:

 

Of the children with neurologic disorders for whom information on vaccination status was available, only 21 (23 percent) had received the seasonal influenza vaccine and 2 (3 percent) were fully vaccinated for 2009 H1N1.

 

 

With September just around the corner, the annual push for flu vaccinations is upon us, and today’s study will hopefully help inspire parents to get all kids – regardless of underlying conditions - vaccinated against influenza.

 

While the effectiveness of flu vaccines vary from year-to-year, and indeed, from one person to the next, they remain the single most important preventative step you can take to avoid getting the flu each year.

 

Despite the hyperbolic anti-vaccine rhetoric often found on the Internet, the truth is, serious adverse reactions to the vaccine are exceedingly rare (see the CDC’s  Influenza Vaccine Safety).

 

With two new strains of seasonal flu expected to be in circulation this winter (Yamagata B, and the Victoria H3N2) – ones that will be covered by this year’s vaccine – getting the flu shot this year is doubly important.

 

CDC recommends that just about everyone aged 6 months and older get an annual influenza vaccination, and stresses their importance for those who are at greater risk of serious complications.

 

For more on vaccine safety and effectiveness, the CDC maintains extensive web pages, and resources, on seasonal flu vaccines, including:

 

What You Should Know for the 2012-2013 Influenza Season

 

Preventing Seasonal Flu With Vaccination

 

Children, the Flu, and the Flu Vaccine

Hantaviruses Revisited

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.

 

• "Facts About Hantavirus" Brochure  [PDF - 182 KB]
  This brochure provides detailed information for prevention of hantavirus in and around your home.
• Información sobre los Hantavirus  [PDF - 296 KB] (Spanish version)
• Campers and Hikers Brochure  [PDF - 322 KB]
  This brochure provides recommended prevention information for outdoor activities.

Podcasts

English

 Hantavirus Pulmonary Syndrome (July 2011)

Listen 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.

Of Mice and Man (January 2010)

Listen 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

Cuando entran los ratones

Listen 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.

The Limits Of Intensity Forecasting

  Source NHC

 

# 6521

 

The 8am EST advisory from the National Hurricane Center finds Isaac close to hurricane strength this morning as he slogs towards the northern Gulf coast at 7 miles per hour. Isaac will be pushing substantial storm surge (6-12 feet) towards the coast, along with high winds, rain, and the potential for tornadoes.  

Hurricane or not, Isaac remains a serious threat and is deserving of respect. 

 

Two days ago forecasters had already accurately predicted a Louisiana/Mississippi landfall - but they also expected Isaac to a strong CAT 2 storm by now. At least one model (HWRF) suggested a low CAT 3 intensity.

 

So what happened?

 

While forecast path prediction has come a long ways in the past 30 years, comparatively little progress has been made in intensity predictions.  

 

The number of atmospheric, oceanic, and land influences on budding tropical systems make it very difficult – with today’s technology – to accurately predict intensity changes 24 to 48 hours out.

 

We’ve often seen storms fail to reach their predicted potential, while others have rapidly intensified beyond any reasonable expectations.

 

Unexpectedly, Hurricane Charlie jumped from a CAT 2 storm to a CAT 4 storm in a matter of a couple of hours just before slamming into Southwest Florida in 2004.

 

This vexing subject was the topic of a presentation last year at the National Hurricane Conference.

 

 

It’s a fascinating 22-page document, but the upshot is, there’s not much hope that intensity forecasting is going to catch up with the recent gains in track forecasting anytime soon.

 

 

All of this uncertainty over storm intensity makes life very difficult for emergency managers.  They must decide – 48 hours in advance of a storm – whether to call for evacuations.

 

And the stakes are very high.

Evacuations are expensive, horribly inconvenient, and have the potential to claim more lives than the storm itself. During the evacuation of the Texas Gulf coast in advance of Hurricane Rita in 2005, more than 90 people died. 

 

And storms that failed to live up to their billing only serve to convince people not to evacuate the next time a storm threatens.

Be glad it isn’t your call.

 

In time, intensity forecasting will hopefully improve.  But tropical storms and hurricanes are complex and dynamic systems, and will probably always have the ability to throw us a curve.

 

All of which highlights the importance of individual, family, and community preparedness.  We must always be prepared for the unexpected.

 

National Preparedness Month is just a few days away, and the folks at FEMA, and READY.GOV would like to encourage you to learn how to make a plan,  build a kit, and be informed.

 

And all next month I’ll be featuring preparedness articles in my blog.

ECDC: Influenza Virus Characterization July 2012

# 6520

 

While we talk about four main strains of influenza that currently circulate in humans (A/H1N1(pdm), A/H3N2, B Victoria, B Yamagata), in reality – within each strain - you will find a good deal of diversity.

 

Influenza viruses are notoriously unstable, mutating at a rapid pace in order to evade acquired immunity. So it isn’t unusual to find numerous genetic variations within the same strain.

 

Even within a single infected host, you’ll find mutations occurring as the virus replicates. Most go nowhere, being genetically flawed, or unable to compete with its more `biologically fit’ parental viruses.

 

But occasionally a competitive strain emerges and crowds out the others. So over time, multiple variations of a viral theme can end up circulating in the human population simultaneously.

 

Sometimes these mutations can move the virus far enough away from earlier strains so that existing host defenses are no longer able to recognize it.

 

That reduces (or eliminates) the immunity acquired by previous exposure or vaccination.

 

When a strain is said to be `antigenically similar’  to the vaccine strain, it is expected (but not assured) that the vaccine remains reasonably effective.  

 

But as these genetic changes accumulate, the effectiveness of a vaccine may eventually erode, and the vaccine strains must be replaced.

 

All of this is part of the normal evolution of influenza viruses, known as antigenic drift. It explains why it is necessary to re-evaluate, and change, the flu vaccine every year or two.

 

NIAID, which is part of the NIH, has a short (3 minute) video that nicely illustrates how flu viruses change antigenically over time, and can eventually mutate so that the current flu vaccine no long is effective.

 

 

 

 

Which brings us to the latest ECDC influenza virus characterization report for Europe. 

 

As you will see, there is a growing diversity in both the H1N1(pdm) and H3N2 virus strains, and they take note of the emerging H3N2v virus in the United States.

 

First the abstract, and a link to the report:

 

ABSTRACT

Since 1 January 2012, influenza A(H1N1)pdm09, influenza A(H3N2) and influenza B/Victoria and B/Yamagata lineage viruses have been detected in ECDC-affiliated countries.

• Type A viruses have predominated over type B.
• A(H3N2) viruses have predominated over A(H1N1)pdm09 viruses.
• A(H1N1)pdm09 viruses continue to show genetic drift from the vaccine virus, A/California/07/2009, but the vast majority remain antigenically similar to it.
• During this time period, all European A(H3N2) viruses sequenced fell within five genetic groups. Test viruses isolated in mammalian cells show low titres with post-infection ferret antisera raised against egg-propagated viruses, including the new vaccine virus A/Victoria/361/2011. They react well with post-infection ferret antisera raised against A/Victoria/361/2011 and other current reference viruses propagated exclusively in tissue culture.
• Recent B/Victoria lineage viruses fell within the B/Brisbane/60/2008 genetic clade and were antigenically similar to reference cell-propagated viruses of the B/Brisbane/60/2008 genetic clade.
• Recent B/Yamagata-lineage viruses fell into two genetic clades, represented by B/Bangladesh/3333/2007 and B/Wisconsin/1/2010 (Clade 3) or B/Brisbane/3/2007 (Clade 2); viruses in these clades are antigenically distinguishable.
• Antigenic analysis of A(H3N2)v viruses, the cause of zoonotic infections in the USA, indicate that they are antigenically distinct from seasonal A(H3N2) viruses.

 

Available as PDF 

 

While the technical details of this report will be of most interest to virologists, epidemiologists, and vaccine manufacturers  . . .  the bottom line is that influenza viruses are a constantly moving target, and as they mutate and change, their ability to infect us improves.

 

Which means that even if you didn’t get the flu last year or the year before, that doesn’t guarantee you won’t get it this year or next.

 

While certainly not 100% protective against all of the flu strains out there, this fall’s reformulated flu shot (see Northern Hemisphere 2012-2013 Flu Vaccine Composition) - along with practicing good flu hygiene - remain your best protections against catching the flu this winter.