H5N1: Hiding In Plain Sight

 

 

Photo Credit – FAO

# 6164

 

A pair of related stories this morning that reinforce the notion that in some places the H5N1 virus may be hiding in the environment, or alternatively, in healthy looking chickens.

 

Neither of which are exactly new ideas, but thus far evidence for both scenarios has been less than overwhelming.

 

First, as study out of Cambodia (h/t Tetano on FluTrackers) that was published on Feb. 17th by the journal Influenza and Other Respiratory Viruses.

 

In this study, environmental samples were collected following outbreaks of bird flu in Cambodia between April 2007 and February 2010.

 

 

Environment: a potential source of animal and human infection with influenza A (H5N1) virus

Srey V. Horm, Ramona A. Gutiérrez, San Sorn, Philippe Buchy

Article first published online: 17 FEB 2012

DOI: 10.1111/j.1750-2659.2012.00338.x

ABTRACT (excerpt)

Results Of a total of 246 samples, 46 (19%) tested positive for H5N1 by qRT-PCRs. Viral RNA was frequently detected in dust, mud and soil samples from the farms’ environment (respectively, 46%, 31% and 15%).

Samples collected from ponds gave a lower proportion of positive samples (6%) as compared to those collected from the farms (24%). In only one sample, infectious virus particles were successfully isolated.

Conclusion During H5N1 virus outbreaks, numerous environmental samples surrounding outbreak areas are contaminated by the virus and may act as potential sources for human and/or animal contamination.

 

It should be noted that given the sensitivity of modern RT-PRC testing, the ability to detect a virus in the environment doesn’t always tell us if it is viable.  That is . . .  whether it remains capable of infecting a host.

 

This report reinforces similar research over the past few years that have expressed similar concerns.

 

During the summer of 2010, in a blog called Of Ducks, And Feathers, And H5N1 we looked at a study that determined that the H5N1 virus may persist on the dropped feathers from infected ducks and that they may spread the virus to the environment.

 

The surprising part of this study is how long these feathers retained some degree of viral contamination at various temperatures.

 

At 4°C (39F) the virus was detectable for 160 days, while at the higher temperature 20°C (68F), the virus was detected for 15 days.

 

The following month, in a study that appeared in Environmental Science and Technology titled:

 

Environmental Persistence of a Highly Pathogenic Avian Influenza (H5N1) Virus

Joseph P. Wood, Young W. Choi, Daniel J. Chappie, James V. Rogers, and Jonatha

n Z. Kaye

DOI: 10.1021/es1016153

Copyright © 2010 American Chemical Society

 

Researchers conducted tests on four inanimate materials (glass, wood, galvanized metal, and top soil) to determine how long – and under what environmental conditions – the virus could survive.

 

They adjusted factors such as  temperature, relative humidity, and simulated sunlight and checked the samples over a period of 13 days.

 

The virus was most persistent at lower temperatures, and on surfaces such as glass and steel. Their conclusion?: at these conditions, the virus would be expected to persist appreciably beyond 13 days.

 

And in November of 2010, we saw an EID Journal study that surveyed LBMs (Live Bird Markets) in Indonesia, and found traces of the H5N1 virus in nearly half of the environmental samples tested (see EID Journal: Indonesian Bird Markets Tested For H5N1).

 

 

Next stop, comments published today in the Indonesian newspaper TEMPO  (h/t Commonground) from Professor C.A. Nidom, of the Institute of Tropical Disease, Airlangga University. 

He repeats a warning that he (and others) have given before; that ineffective or improperly dispensed poultry vaccines can mask H5N1 infection in poultry, allowing people to be exposed via `healthy looking’ chickens.

 

 

Wednesday, February 22, 2012 | 10:43 pm

Can Bird Flu Virus Found in Poultry Healthy

TEMPO.CO, Jakarta - Head of Avian Influenza, Zoonosis Research Center University of Airlangga, CA Nidom, said that the bird flu virus (H5N1) can be found in healthy birds. Under these conditions because the vaccine is given to poultry.

He said the bird flu in poultry vaccine made antibodies to poultry so that the birds will stay healthy and not die even if hit by bird flu virus. As a result, signs of the virus has already infected, but not seen. So that public awareness is less because they think that their birds have in a healthy state.

"Our research states that avian flu has been vaccinated birds can still carry the virus even look healthy," he said by telephone on Wednesday, February 22, 2012.

(Continue . . .)

 

If this sounds familiar, you may recall that Dr. Nidom has previously warned on using poultry vaccines to control Indonesia’s bird flu problem (see Indonesia: Debate Over Poultry Vaccination), as opposed to culling.

 

Similar warnings were expressed in early 2009 from Zhong Nanshan, a hero of the SARS outbreak and a highly respected respiratory disease specialist in China, who warned that vaccinated poultry can still become infected with the H5N1 virus.

 

Chinese expert issues new bird flu warning

www.chinaview.cn  2009-02-06 17:59:50

GUANGZHOU, Feb. 6 (Xinhua) -- A leading Chinese expert on respiratory diseases has warned the public to be aware that poultry can be infected with the bird flu virus but show no symptoms.

 

"Special attention should be paid to such animals, including those that have been vaccinated," said Zhong Nanshan.

 

"The existing vaccines can only reduce the amount of virus, rather than totally inactivating it," he said.

(Continue . . . )

 

The OIE (World Organization For Animal Health) has been aware of the potential of vaccines to hide infection for many years, warning that vaccination of poultry cannot be considered a long-term solution to combating the avian flu virus.

 

In Avian influenza and vaccination: what is the scientific recommendation?, the OIE reiterates their strong recommendation that humane culling be employed to control avian influenza, and advising that vaccines should only be used as a temporary measure.

While the OIE concedes that some nations may require the use of vaccines for `several years', they strongly urge that countries move away from that program and towards the more conventional culling policy.

They call this shift away from vaccines an `Exit Strategy’, something which China, Indonesia, Vietnam, and have shown no move towards.

 

And the big news now out of Vietnam over the past year has been the failure of their poultry vaccine against the emerging 2.3.2.1 clade of the virus which is now widely circulating in the north.

 

In August 2011 the FAO issued a statement on this 2.3.2.1 clade (see FAO Warns On Bird Flu) that is not covered by currently available poultry vaccines.

 

Despite the growing concerns over asymptomatic poultry carrying the H5N1 virus, and evidence of environmental contamination by the virus, the limited number of human cases we have seen to date indicate that the virus still has a hard time infecting humans.

 

It is adapted to avian physiology – not human - and must mutate further if it is to become an imminent public health threat.

 

But with 20+ clades of the virus now circulating, and numerous opportunities to expose and infect other hosts (human, swine, mammal, and avian), the virus may one day succeed.

 

 

Which is why the world remains in pre-pandemic phase III on the H5N1 virus, and we watch its progress intently.

»» Read More

Indonesia: Concerns Over Changes In Avian Flu Symptomology

 

Photo Credit – FAO

# 6142

 

With influenza viruses, the only true constant is change.

 

Viruses must continually evolve and adapt in order to survive. The legacy of infection by a virus is usually some degree of immunity, and if viruses did not evolve they would soon run out of susceptible hosts.

 

Minor mutations happen all of the time, but most turn out to be evolutionary dead-ends. They confer no biological advantage to the virus, fail to thrive, and die out. 

 

It is only when the right combination of changes occurs that changes the virus’s antigenic profile or enhances transmissibility or replication – or expands its host range – while still remaining `biologically fit’, that a new strain begins to flourish and spread.

 

And those types of changes can happen very quickly, or they can take years in coming.

 

It is this evolutionary process that has led to having 20+ clades (major versions) of the H5N1 virus circulating around the world, including the vaccine resistant strain clade 2.3.2.1 (see  FAO Warns On Bird Flu) that began to emerge in 2010.

 

 

With so many different clades in circulation, it is no wonder we see some variations in the way the virus behaves.

 

All of which serves as prelude to a long report appearing today in the Indonesian Newspaper Kompas, which talks about a moderation in outward signs of infection among poultry.

 

 

Those with long memories may recall we discussed similar concerns back in 2009 (see Bird Flu Symptoms Changing In Indonesia).  Three years ago the Dean of Faculty of Veterinary Medicine, Institut Pertanian Bogor was quoted as saying:

 

“Common signs as cyanosis of wattle, comb or fetlock are not observed anymore. Mortality also decreases so that it’s difficult to differ between ND and AI”

 

So while perhaps becoming more common today, these changes do not appear to be entirely new.

 

Included are also some comments by Professor C.A. Nidom, on the dangers of H5N1 reassortment. My thanks to Shiloh on FluTrackers for finding, and translating the following article (original link).

 

Be warned, this is a machine translation, and so the syntax is a bit mangled. 

 

Can Bird Flu Virus More Dangerous

Asep Chandra | Tuesday, February 14, 2012 | 9:28 pm

Jakarta, Kompas - The bird flu virus (H5N1) in Indonesia is thought to have changed. The virus is feared more dangerous than before. Further research is needed to ensure the fatality rate of the new virus.

 

Reports from a number of areas, until Monday (13/Feb), indicating the change. Even so, not yet ascertained the impact of the change.

 

Head of Animal Husbandry and Animal Health in Central Java Semarang District Whitono reveals, some poultry that died of bird flu now has features that are not as usual, ie no black or bluish spots on the comb or body part that is not hairy.

 

Meanwhile, Head of Animal Health Animal Husbandry and Animal Health Central Java Eko Sutarti revealed, though not sure about the new virus, characteristics of birds that died of bird flu part shifted. Usually the birds that died of bird flu are marked with blue or black spots on the comb or body parts that are not covered in fur.

 

Now the poultry that died suddenly without these spots were found positive for bird flu.

 

Of Brebes, Central Java, reportedly, the body's defense system against virus attacks poultry in the region changed when compared with previous years. This is evident from the clinical symptoms found in cases of chicken deaths in the region last week.

Head of Animal Health and Veterinary Public Health Veterinary Services Brebes Jhoni Murahman say, around 2003, when he first outbreak of bird flu virus in Bradford, clinical symptoms of bird deaths at that time happened very quickly and in large quantities.

 

Physical signs in birds that died of bird flu is also very clear, that the body was black, very much saliva, swollen heads and blue crest on the head.

 

However, at present, clinical symptoms are not very visible. Poultry deaths tend to be in unison, but one by one. Body of dead birds as well just turn blue with not a lot of saliva and the head is not swollen.

Chairman of the Avian Influenza Research Center, zoonosis, which is also a lecturer at the Faculty of Veterinary Medicine Airlangga University, Surabaya, CA Nidom, say, the existence of the bird flu virus in Indonesia to worry about. "There are allegations of meetings between the H5N1 virus (bird flu) and pan2009 A H1N1 (swine flu) in Indonesia. This could produce a new type of virus is more dangerous, "he said.

 

(Continue . . . )

Over the years concerns have been voiced that inconsistent or poorly matched poultry vaccination programs could be driving the evolution of the H5N1 virus.

 

As new clades emerge, vaccination of birds with existing vaccines may still lessen morbidity and mortality in the flocks, but not prevent infection.

 

Creating, in a sense, a `stealth' bird flu virus; one that doesn't announce itself with clearly observable symptoms.

 

And that, one would have to assume, only serves to increase the chances that more people and more poultry will be inadvertently exposed to the virus.

»» Read More

UK: H1N1 Serology Tests Reveal Significant Asymptomatic Rate

 

 

# 4074

 

It comes as no surprise that a certain percentage of people who are exposed to the pandemic flu virus go on to develop antibodies without experiencing clinical symptoms. 

 

With seasonal flu, it is expected that anywhere from 1/3rd to 1/2 of people exposed, never fall ill.

 

But when a new virus appears, until serology tests can be conducted, we don’t have a good handle on what percentage might remain asymptomatic.

 

 

Earlier this months I reported on New Zealand’s plans to test the blood of 2,500 people (see New Zealand To Conduct Seroprevalence Studies) to try to determine the actual rate of infection over the summer.  Other countries are doing so, as well.

Today we learn of a relatively small study, conducted in the UK, of school aged children to determine how many have elevated antibody titers to the novel H1N1 virus.  

 

The results are encouraging, in that a substantial percentage (about 1/3rd) of the children tested show antibodies to the virus, while only about 1 in 10 reported flu symptoms.   

 

This report from the BBC.

 

 

More children 'than expected have had swine flu'

 

By Nick Triggle
Health reporter, BBC News

Up to a third of children in some areas may have had swine flu, but many will not have been ill, analysis shows.

The Health Protection Agency has reviewed blood tests which showed higher levels of infection among children than originally thought.

 

In hotspot areas, such as London and the West Midlands, a third of school-aged children may have had the virus, but only one in 10 or less got ill.

 

Across the UK, the figure is probably about a fifth, the HPA said.

 

The findings reinforce the fact the pandemic is a mild strain of flu.

 

Flu, whether it is seasonal or swine, always affects more people than actually get ill.

 

The ratio is normally about 50-50 and pandemic flu is probably not much different, the HPA said.

 

(Continue . . . ) 

 

Fergus Walsh, medical correspondent for the BBC, who writes the Fergus on Flu blog, has more at:

 

Up to a third of children in some areas have been infected

Fergus Walsh | 16:54 UK time, Tuesday, 24 November 2009

»» Read More