Did new flu emerge from a pig farm?

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From ANIMAL PEOPLE, May 2009:

 

 

Did new flu emerge from a pig farm?

 

MEXICO CITY--Rumors swept the world

during the last week of April 2009 that a newly

detected H1N1 flu virus variant suspected of

killing as many as 149 Mexicans might have

evolved at a factory-style pig farm at Perote,

in Vera Cruz state on the Gulf of Mexico. As

ANIMAL PEOPLE went to press on the night of April

28, however, little medical or veterinary

evidence supported the hypothesis that the

disease is of factory farm origin, and some

evidence seemed to refute it.

Among the first 1,995 suspected Mexican

cases of the new flu strain, only 27 were

laboratory-confirmed. Lab-confirmed human cases

had occurred in 19 other nations, including 64

cases in the U.S., but no deaths were reported

outside of Mexico.

Bloggers and news media usually called

the virus " swine flu, " but although it contained

genetic material of swine origin, nothing linked

it to recent swine infections.

The Perote farm belongs to the Mexican

firm Granjas Carroll, a half-owned subsidiary of

Smithfield Inc., the world's largest pork

producer. Smithfield spokesperson Keira Ullrich

told media that an internal investigation had

found no clinical signs or symptoms of swine

influenza in animals and employees at any of its

Mexican facilities. A United Nations' Food &

Agriculture Organiz-ation team reportedly reached

Pecote on April 28 to seek independent

confirmation.

" We deny completely that the influenza

virus affecting Mexico originated in pigs because

it has been scientifically demonstrated that this

is not possible, " claimed the Mexican National

Organization of Pig Production and Producers.

That was an exaggeration, but at press

time the case for factory farm involvement

appeared to rest on the coincidence that the

earliest identified case of the new H1N1 virus

variant was detected in 5-year-old Edgar

Hernandez, who lives near the Granjas Carroll

pig farm.

Hernandez fell ill on April 2, Mexican

health secretary Jose Angel Cordova told media.

Many other Perote residents fell ill at about the

same time, but " Only one sample from the group,

that belonging to the boy, was preserved, "

reported Tracy Wilkinson and Cecilia Sanchez of

the Los Angeles Times. " It was retested after

other cases of the new strain were confirmed

elsewhere in the country, Cordova said. The boy

had the same disease. It is unknown how many

more of the hundreds of people who fell sick in

Perote also were infected by the strain. "

" In Perote, " Wilkinson and Sanchez

found, " residents of the hamlet known as La

Gloria have complained since mid-March that the

pig farm was tainting their water and causing

respiratory infections. In one demonstration in

early April, they carried signs with pictures of

pigs crossed out with an X and the word

'peligro'--danger. Residents told reporters at

the time that more than half the town's 3,000

inhabitants were sick, and that three children

under age two had died.

" Local health officials mobilized when

the outbreak was first reported, " Wilkinson and

Sanchez reported, " but they gave a different

account: The infection may have started with a

migrant farmer who returned from work in the U.S.

and gave the disease to his wife, who in turn

passed it to other women in the community. "

" La Gloria was not alone in experiencing

a fierce flu outbreak in recent weeks, " noted

Marc Lacey of The New York Times. " Public health

officials in other parts of Mexico said they had

noticed an unusual spike in cases in the

beginning of April, when the normal flu season

would usually end. "

Door-to-door census taker Maria Adela

Gutierrez, 39, of Oaxaca, capital city of

Oaxaca state, on April 13 became the first

confirmed fatality from the new H1N1 strain.

 

James Wilson, MD

 

Most reports associating the Perote pig

farm with the H1N1 outbreak, including two

widely distributed columns by Grist food editor

Tom Philpot, referenced a biosurveillance web

site and blog posted by James M. Wilson V, M.D.,

of Seattle.

Wilson has done biosurveillance for the

U.S. armed forces, the USDA, NASA, and the

Centers for Disease Control and Prevention,

among other agencies, and is cofounder of the

Veratect Corporation, which " provides animal and

human infectious disease event detection and

tracking globally, " says his online biographical

page.

But Wilson was more cautious than many of

the people who used his material.

" One key myth I wish to dispel, " Wilson

updated on April 27, " is the claim that there

was any credible link to a pig farm. Such claims

must be verified through solid epidemiological

investigation. "

Wilson on April 24 posted a " Swine Flu in

Mexico " timeline that began with a March 30

report that " a 47-year-old attorney was

hospitalized in a coma at Ottawa General Hospital

following a recent trip to Mexico. "

On April 27 Wilson acknowledged that this

case " tested negative according to Canadian

officials, " and that there was therefore no

reason to link it to H1N1.

On April 2, the timeline continued,

" Local media source Imagen del Golfo reported

that [Vera Cruz] state health officials recorded

a 15% increase in disease over an unspecified

period in the highland areas of Vera Cruz, which

includes La Gloria. The increase was primarily

due to higher levels of upper respiratory disease

and gastroenteritis. Specifically, officials

noted an increase in pneumonia and bronchial

pneumonia. Health officials attributed the

increase to seasonal climate changes. "

On April 6, recounted Wilson's timeline,

" Local health officials declared a health alert

due to a respiratory disease outbreak in La

Gloria. Sources characterized the event as a

'strange' outbreak of acute respiratory

infection, which led to bronchial pneumonia in

some pediatric cases. Health officials recorded

400 cases who sought medical treatment in La

Gloria, population 3,000; officials indicated

that 60% of the town's population had been

affected. No precise timeframe was provided,

but sources reported that a local official had

been seeking health assistance for the town since

February. Residents claimed that three pediatric

cases, all under two years of age, died from

the outbreak, " as Wilkinson and Sanchez of the

Los Angeles Times confirmed.

" However, " Wilson continued, " health

officials stated that there was no direct link

between the pediatric deaths and the outbreak;

they stated the three fatal cases were 'isolated'

and 'not related' to each other. "

 

Flu or biting flies?

 

Continued the April 6 timeline entry,

" Residents believed the outbreak was caused by

contamination from pig breeding farms operated by

Granjas Carroll. According to residents, the

company denied responsibility and attributed the

cases to 'flu.' " This was apparently the first

mention of flu in connection with the La Gloria

disease outbreak.

" However, " the timeline added, " a

municipal health official stated that preliminary

investigations indicated that the disease vector

was a type of fly that reproduces in pig waste,

and that the outbreak was linked to the pig

farms. It was unclear whether health officials

had identified a suspected pathogen responsible

for this outbreak. "

Many insect-borne diseases produce

flu-like symptoms, including the ricketsial and

malarial disease families--but the ricketsial

diseases are caused by bacteria, and the

malarial diseases by protozoan parasites.

On April 27, Wilson posted that his

timeline mention of flu " was simply to flag an

event as worthy of closer scrutiny and higher

awareness, as there was absolutely no proof of

true involvement of this company in the outbreak.

A proper epidemiological investigation is

required to prove such links. "

Meanwhile, added the April 6 Wilson

timeline entry, " A health cordon was established

around La Gloria. Officials launched a spraying

and cleaning operation that targeted the fly

suspected to be the disease vector. State health

officials also implemented a vaccination campaign

against influenza, although sources noted

physicians ruled out influenza as the cause of

the outbreak. Finally, officials announced an

epidemiological investigation that focused on any

cases exhibiting symptoms since March 10. "

Ten days later, on April 16, wrote

Wilson, " Veratect reported the Oaxaca Health

Department indicated that an unspecified number

of atypical pneumonia cases were detected at the

Hospital Civil Aurelio Valdivieso in Reforma,

Oaxaca State, Mexico. No information was

provided about symptoms or treatment for the

cases. NSS Oaxaca reported that rumors were

circulating that human coronavirus was spreading

at the hospital; sources did not provide any

response to these statements from the hospital or

health officials. Laboratory samples were sent

to Mexico City for analysis. According to NSS

Oaxaca, health officials intensified preventive

measures aimed at mitigating further spread of

the disease. "

 

Why " swine flu " ?

 

Explained ProMED animal disease moderator

Peter Cowen on April 25, " The H1N1 virus is

called 'swine flu' because of the outbreak of the

1918 virus that caused significant mortality in

both swine and human populations. The virus

probably has a wild bird origin, " as all

influenzas have evolved from avian diseases.

" Influenza viruses regularly circulate in

swine populations, " Cowen continued. " Swine flu

viruses have been known to infect humans, [but]

it appears as if no exposure to swine has

occurred among people who have come down with the

current novel H1N1 virus. Since we know nothing

of how this particular virus has gotten into the

human population, but there apparently is no

history of swine exposure, it probably makes

more sense epidemiologically to refer to this

simply as an H1N1 influenza.

" Unfortunately, " Cowen concluded, " the

name 'swine flu' will imply a simple transmission

between swine and people, when in reality its

origin and epidemiology are likely to be much

more complex. "

Elaborated fellow ProMED animal disease

moderator Arnon Shimshony, " Swine influenza in

senso stricto, " unlike the common use in

connection with the H1N1 virus afflicting humans,

" is an animal disease, caused by a specific

porcine virus. Swine influenza viruses are very

contagious, mainly affecting pigs, but can

sporadically cause disease in turkeys and humans.

Such an interspecies infection, when occurring,

is not followed by further spread in the affected

populations, " who become dead end hosts.

" The current influenza virus spreads

readily among humans without any known

involvement of, or contact with pigs, "

Shimshony emphasized. Thus, regardless of

origin, " The causative virus can persist among

humans independent of animal involvement. "

 

Genetic link

 

Assistant professor Raul Rabadan, PhD.

of the Department of Biomedical Informatics at

Columbia University on April 28 shared with

ProMed members the strongest medical hint before

ANIMAL PEOPLE went to press that the H1N1

outbreak might be associated with pig farming.

But Rabadan's finding did not point directly

toward factory pig farming, or even to pig

farming per se.

" My group and I are analyzing the recent

sequences from the isolates in Texas and

California of swine H1N1 deposited in the

National Center for Biotechnology Inform-ation, "

Rabadan posted. " Preliminary analysis using all

the sequences in public databases suggests that

all segments are of swine origin, " contrary to

earlier reports that the new H1N1 virus included

elements from human and avian viruses. Rabadan's

team found the parts of the new virus " related to

Asian/European swine and the rest to North

American swine. There is also an interesting

substratification between these groups, " Rabadan

observed, " suggesting a multiple reassortment. "

Rabadan's findings pointed toward the new

H1N1 virus originating in pigs. However, the

mix of Asian/European swine and North American

swine virus segments may point toward hybridized

boars, commonly raised for hunting and the

restaurant trade-- and feral in much of North

America--rather than factory-farmed pig breeds.

However, reminded the British

Department of Food, Agriculture, and Rural

Affairs later in the day, " The virus has not

been isolated from pigs, and there have been no

reports of unusual disease in pig herds.

" H1N1 and H3N2 swine flu viruses are

endemic among pigs in many countries and

something that the industry deals with

routinely, " DEFRA continued. " Outbreaks among

pigs normally occur in late fall and winter.

U.S. studies have shown that between 30% and 50%

of the pig population have been exposed to H1N1

infection at some time. Mexico does not

routinely report swine influenza, " DEFRA noted,

" so there is some uncertainty regarding the

situation in that country. "

However, DEFRA concluded, " We consider

there is a negligible likelihood of introducing

human influenza strain H1N1 to the U.K. by the

legal import of pigs or pig products from North

America. There is no evidence that meat or other

products would be contaminated with known strains

of virus. "

Commented the Office International des

Epizooties [World Organization for Animal Health]

in a parallel statement, " The virus has not been

isolated in animals to date. Therefore, it is

not justified to name this disease swine

influenza. Urgent scientific research must be

started in order to know the susceptibility of

animals to this new virus, " the OIE said, " and

if relevant to implement biosecurity measures,

including possible vaccination to protect

susceptible animals. "

 

Mixing vessels

 

Speaking before Rabadan released his

genetic findings, OIE director general Bernard

Vallat told Agence France-Presse that the new

H1N1 virus contains an avian strain of American

origin, and American swine strain and an

apparent Asian swine strain, and an American

human strain. But even with that mix, Vallat

explained, " There is no proof that this virus,

currently circulating among humans, really is of

animal origin. There is no element to support

this. "

Both pigs and humans are influenza

" mixing vessels, " within whom different flu

strains can meet, incubate, and mutate.

Regardless of the medical evidence,

animal advocates seized upon the H1N1 outbreak as

an opportunity to expose and denounce aspects of

factory farming other than disease transmission.

Posted Michigan activist Liska,

" What intensive confinement factory farming has

done to the animals, in terms of the cruelty

involved, the drugs used to offset the disease

and stress caused to the animals by how they are

overcrowded and not allowed to meet their basic

behavioral needs, etcetra, is going to come

back to haunt us until we change our ways, and

that doesn't even include the human side effects

from eating meat filled with antibiotics and

hormones. "

" For more than 23 years we have warned

that cramming thousands of animals into factory

farms is not only bad for the animals, " said

Farm Sanctuary cofounder Gene Baur. " These

stressful, filthy, disease-ridden confines are

also bad for humans. Animals packed by the

thousands in unnatural conditions suffer

immensely and these unhealthy, overcrowded

operations are a breeding ground for

disease--swine flu, avian flu, e-coli,

salmonella, mad cow diseaseŠFactory farms are a

prescription for disaster. "

Baur mentioned pending federal

legislation which, if passed, " would eliminate

the use of sub-therapeutic antibiotics on factory

farms. "

This measure is favored by most of the

human health community as well as animal

advocates, since heavy use of antibiotics in

farming is tending to increase the capacity of

infectious bacteria to resist antibiotic

treatment. --Merritt

Clifton

 

 

--

Merritt Clifton

Editor, ANIMAL PEOPLE

P.O. Box 960

Clinton, WA 98236

 

Telephone: 360-579-2505

Fax: 360-579-2575

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Web: www.animalpeoplenews.org

 

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