Looming Danger of Bird Flu
Over 35,000 fowls were culled following bird flu outbreaks in three districts of Borguna, Rajshahi and Jessore in the past week, official sources said. Experts fear the H5N1 strain could mutate and pass on to humans. However, no human infections have so far been reported in the country.
Some 11,243 chickens, ducks and pigeons were slaughtered and 2,000 eggs were destroyed in Barguna, Patuakhali and Dinajpur districts in last two days after detection of avian influenza. Suspected outbreaks were also reported at a farm in Rangpur, where the virus has resurfaced. Bangladesh needs house-to-house surveillance to fight bird flu because the situation has worsened (New Nation, January 27, 2008)
(Afp, Kolkata, January 24. 01.08) India's West Bengal state said yesterday it was falling behind in its attempts to halt the spread of bird flu among poultry as the virus was confirmed in two new areas. Despite receiving reinforcements from neighbouring states to help slaughter more than two million birds, at least 1,000 additional veterinarians and doctors are needed to fight the outbreak that began more than a week ago, the state's animal resources minister said.
"We don't have the infrastructure to battle this epidemic. Bird flu is spreading to new areas. Thousands of chickens are dropping dead every day," the minister, Anisur Rahaman, told AFP. Rahaman said hundreds more culling teams had been sent to 10 districts where bird flu had been confirmed, but not all of them were accompanied by medical staff.
"We have asked neighbouring states to send at least 1,000 veterinary and human doctors," said Rahaman. "We have urged the federal government to send expert teams and doctors to assess the situation and help the culling teams." Rahaman also said the earlier target of slaughtering two million birds would now have to be raised but did not say by how much.
"Bird flu has spread to two more districts in West Bengal. It has been confirmed by telephone," said Rahaman. "We have to kill more poultry. The target will be more than two million." The latest outbreak began in the village of Margram, 240 kilometres from the state capital Kolkata. It is the third and worst to hit India since 2006, which has so far not had any human cases of bird flu.
Recent avian influenza outbreaks in 15 countries demonstrate that the H5N1 strain of the virus remains a global threat and requires close monitoring and strong control efforts.
A FAO press release yesterday said since December 2007, Bangladesh, Benin, China, Egypt, Germany, India, Indonesia, Iran, Israel, Myanmar, Poland, Russia, Ukraine, Turkey and Vietnam have confirmed new H5N1 outbreaks in poultry stocks. Except for a few cases in wild birds in China, Poland and United Kingdom, most of the confirmed outbreaks occurred in domestic poultry, including chickens, turkeys, geese and ducks.
In Bangladesh, 21 out of 64 districts have been infected with H5N1 and the situation seems to be worsening. The disease appears to be endemic in the country, surveillance and control campaigns have so far not succeeded in interrupting virus transmission between provinces. FAO is strengthening its presence in Bangladesh to support the government in its efforts to bring the disease under control. In Europe, Germany, Poland, the Russian Federation and the United Kingdom reported new avian influenza outbreaks recently
With FAO's assistance, more than 50 countries have been able to control and eliminate the disease in poultry. "Surveillance and immediate control interventions, bio-security, proper vaccination and culling and the strengthening of veterinary services are key elements for successful H5N1 avian influenza control campaigns," Domenech said (Daily Star, January 25, 2008).
The World Health Organization Sunday confirmed two Vietnamese women recently died from bird flu, and said they may have caught the illness from their brother.The two sisters, ages 23 and 30, both fell ill on Jan. 10, the WHO said. They were admitted to a hospital three days later and died on January 23 (CNN, February 1, 2004).
The WHO said it is still trying to confirm the source of the infection for the two sisters. "WHO considers that limited human-to-human transmission, from the brother to his sisters, is one possible explanation," the organization's statement said.
The sisters are part of a cluster of four cases of respiratory illness in Thai Binh province, including their brother and his wife.
The brother died shortly before his sisters were hospitalized, but it is not clear if he was infected with the H5N1 bird flu because no samples are available to test.
"The investigation failed to reveal a specific event, such as contact with sick poultry, or an environmental source to explain these cases," according to the WHO statement. "At the same time, such exposures cannot be discounted, either."
Experts from the World Health Organization and the United Nations warned that the bird flu outbreak plaguing Asia has the potential to be more deadly than SARS, and that Vietnam -- the country worst hit so far -- is ill-prepared to cope. If the H5N1 virus attaches itself to the common human flu virus and if it is then effectively transmitted, it has the potential to cause widespread damage," said Peter Cordingley, a spokesperson for WHO.
Ripe conditions for pandemic virusExperts warn that conditions are ripe in Asia to spark the next human flu pandemic: the H5N1 virus is already endemic and evolving in both domestic and wild birds in Asia and is becoming more virulent; it has already infected and killed some people who had close contact with birds, and has been found in pigs - the ideal 'mixing vessels' for bird and human flu viruses to swap genetic material to produce a lethal virus able to spread rapidly from person to person; other animals also have the potential to serve as mixing vessels.
More and more animal diseases are “jumping” the species barrier to infect human beings, and the avian influenza strain H5N1 is no exception (see “Connecting the Dots,” cover story, November/December 2004). According to the World Health Organization (WHO), since 2003, 170 people have contracted avian influenza H5N1, 90 of whom have died. Most of the human cases have occurred in Asia, and in places where people have direct contact with diseased poultry—either on farms or during preparation of the meat. The WHO has documented that the H5N1 virus spread to 13 new countries last February. Azerbaijan, Bulgaria, Greece, Italy, Slovenia, Austria, Iran, Germany, France and Hungary have all found the virus in wild birds. Egypt, India and Nigeria have discovered infected domestic poultry.
The virus does not currently have the ability to spread between humans, but according to the WHO, “The risk of pandemic influenza is serious…The number of deaths caused by a pandemic virus vary greatly, and cannot be known prior to the emergence of the virus. During past pandemics, attack rates reached 25 to 35 percent of the total population.” The more the virus spreads across the world, the greater the chances a pandemic can occur (Our Planet, June 2006).
"This mortality rate is far higher than that of the SARS virus," Cordingley said. "The common human flu virus is far more infectious than the SARS virus and can be spread by aerosol and not just through droplets as in the case of the SARS virus. "Bird flu could be potentially more dangerous than SARS if it attaches itself to the common flu virus, and if this new virus is then effectively transmitted like the common flu virus, we have the potential for widespread damage," he added.
The virus is normally transferred from birds to human beings but scientists are worried it could now be passing from person to person - with potentially devastating consequences.
Five years ago, the world was put on high alert when six people in Hong Kong were killed by bird flu. Nearly a million chickens were slaughtered in an attempt to stop the spread of the virus. If the Hong Kong strain were to spread it would be the fourth major flu outbreak in the province in the past five years. Each one has led to massive bird culls.
Governments battling the disease are: China, Thailand, Vietnam, Indonesia, Cambodia, Japan, South Korea, Laos, Taiwan and Pakistan. However, the strain of bird flu striking Taiwan and Pakistan is different from the one hitting the other countries and is not considered a serious threat to humans. The World Health Organization urged China to take swifter action Saturday (January 31, 2004) as the world's most populous country reported two new suspected outbreaks.
When Thailand reported its first human death caused by avian influenza (in January 2004), the government took a bold step to protect our poultry industry from the spread of the virus. Imports of parent stock chicks (chicks from which local hatcheries breed broiler and layer chicks) were banned from several Asian countries. Most of the banned countries (Pakistan, Vietnam, Thailand, South Korea, Japan, and Taiwan) had already reported or have since reported avian influenza outbreaks. Two of the banned countries (India and Malaysia) have not reported outbreaks; they were banned because they were rumoured to have outbreaks. The ban was successful; there has not yet been any outbreak of avian influenza in Bangladesh (Daily Star, August2, 2005).
Avian influenza is sweeping across Asia, killing birds in Russia, Kazakhstan and Mongolia. And the strains found in Russia and Kazakhstan are the deadly H5N1 virus, say officials. Furthermore, the strain found in Russia appears to be the same genetic sub-type as that recently found in migratory birds in China – hinting the virus could be carried much farther, possibly even to Europe and the Americas.
Thailand, Cambodia, Vietnam and Indonesia have suffered 57 human deaths from the H5N1 virus out of 112 cases, according to the latest figures from the World Health Organization on 5 August. On Wednesday, the world animal health body, the OIE also said bird flu had spread to the Tibet region of China.
Mongolia confirmed cases of the H5 virus as 80 wild ducks, geese and swans were found dead. “The H5N1 outbreak in wild birds appears to have extended its range to include Western Mongolia,” writes Peter Cowen, at the College of Veterinary Medicine, North Carolina State University and animal disease assistant-moderator of ProMed Mail, an infectious diseases mailing list.
Genetic sequencing of a particular fragment of the virus relating to its virulence shows it is “analogous to the sequence of the highly virulent [H5N1 sub-type] found in three species of migratory water birds during the epidemic in May and June on Qinghai Lake in China, writes Evgueny Nepoklonov, head of the main veterinary department at the Russian ministry.
Sequence data from virus that infected a turkey in the Novosibirsk village of Suzdalka, links the virus back to even older outbreaks: “According to the sequence data, the cleavage site structure is practically identical to that of the highly pathogenic strain of sub-type H5N1 isolated in Hong Kong in 1997,” says the Russian report.
This suggests the virus could be spread by migratory birds. Previously this had been thought unlikely, with a more probable explanation believed to be that infected wild fowl got the virus from locally infected poultry after landing.
But if migratory birds are spreading H5N1, the concern is it could spread around the globe. Indeed scientists in Alaska are already studying migratory birds for avian flu, as migrating fowl from both Asia and America cross paths in Alaska. “We could potentially have overlap of viral strains from the Americas and Asia,” Jonathan Runstadler, at the University of Alaska Fairbanks Institute of Arctic Biology, US, told the Associated Press.
He and his colleagues are to take intestinal swabs from 5000 birds of 25 species throughout the state for testing. But no Alaskan migratory birds have ever shown signs of bird flu, note the scientists. Concerns that bird flu could spread to western Europe via migratory birds were discussed by scientists at a meeting organised by Switzerland’s Federal Veterinary Office on Tuesday in Bern. They concluded that although two infected bird species – the pochard and tufted duck – do migrate to Switzerland from Eurasia, they were unlikely to bring the virus (New Scientist, August 26, 2005).
Spectre of Avian Flu looms
Avian Flu, or Bird Flu, may break out any time in the country causing severe losses to the poultry industry, one of the fastest growing and most promising industries in the country. A recent research (February 2005) of Bangladesh Livestock Research Institute (BLRI) has revealed the fact.
The research revealed that the latest outbreak of Avian Flu has occurred in last January (2005) in some of the farms in Thailand, Vietnam, Indonesia, Hong Kong, Russia, Pakistan, Cambodia, China, Malaysia and Japan. Though the disease was not detected in Bangladesh, yet it may break out anytime here due to its geographic location. If once the disease breaks out in Bangladesh, it might cause tremendous damage to the fast growing poultry industry of the country since the condition and management of most of the poultry farms in the country is not scientific, revealed the research.
About 35 lakh (3.5 million) people in the country are employed in the poultry sector that adds a value worth Taka 5000 crore ($ 833 million) to the country’s GDP. The vibrant industry has provided source of income to 20 per cent of the country’s half-educated and unemployed rural youths including females. The potential of this sector is not even half-utilised in the country.
Last year many Asian countries, especially Thailand, Malaysia, Cambodia, Vietnam, Hong Kong, China, Pakistan and Japan, were seriously affected by the Avian Flu. Following the impact of the outbreak, 35 people died and more than 75 million birds were slaughtered and cremated to get over the epidemic. Though Bangladesh was not affected by the outbreak of Avian Flu last year, it had to bear the brunt of the epidemic in the neighbouring countries. At least 10 thousand broiler farms and 50 day-old-chicken (doc) breeding hatcheries across the country have been closed down since the outbreak of Avian Flu last year.
According to poultry farmers, to feed the potential industry, 130 hatcheries and 1,60,000 commercial layer farms have been set up throughout the country. Some 34 lakh (3.4 million) pieces of 1-day chickens and 2,60,000 metric tons of meat are produced annually. The research recommended for taking some administrative steps to prevent epidemic of Avian Flu. It recommended that illegal entrance of poultry, poultry feed and poultry related materials be banned. It also called for a ban on importing these things from the affected as well as neighbouring countries that have experienced the disease. The study suggested taking effective measures for laboratory test of 1-day chicks and sending the report to the authorities and exchanging views with poultry specialists regularly (Independent, February 28, 2005).
What is bird Flu?All those infected in the Far East outbreak caught the disease directly from birds but experts warned that if the virus mutates and acquires the capacity for human-to-human transmission, the impact could be devastating.
According to experts, water birds are the reservoir for all 15 kinds of influenza type A. This means that ducks and geese carry the viruses. They don’t always get sick, so the basic seeds for the 15 kinds of flu are always out there.
Sometimes these flu strains mutate into more dangerous forms known as highly pathogenic avian influenza (HPAI). HPAI is extremely lethal to chickens. And it can be very dangerous to humans who catch the disease from domestic poultry.
Contact with bird droppings is the most likely way people catch bird flu. People do not catch the virus from eating cooked chicken or eggs.
Bird flu tends to be an intestinal disease spread through faeces. Human flu tends to be a respiratory disease spread by droplets (coughing, sneezing). The only way a bird flu virus can spread easily from one human to another is if the bird flu strain changes by picking up some genes from a human flu virus, a possibility that the WHO has cautioned against. Humans who have caught this year’s bird flu from chickens start out with normal flu-like symptoms. This worsens to become a severe respiratory disease that has been fatal in a high percentage of cases.
The bad news is that the H5N1 strain that the current attack of bird flu is suspected to be carrying is immune to most flu drugs. However, the drug is responsive to the newer flu drugs like Tamiflu and Relenza.
At present the avian influenza strain, known as H5N1, is not thought to be capable of passing from person to person. But there are fears that it might acquire that ability if its DNA mingled with that of a human flu virus. Such genetic "reassortment" is a well-known feature of viruses. An editorial in the UK medical journal the Lancet today says that standard vaccines would be useless against the virus if it started spreading.
Klaus Stohr, head of the WHO's global influenza program, said in Geneva Wednesday , January 28, 2004 that it was taking these precautions in case there was "significant human to human transmission", Reuters reports. While there is no evidence yet of human-to-human transmission, the Asian victims have all been people who handled infected birds, and experts have advised people to avoid going to poultry farms and food markets with live animals.
As bird flu spreads around Asia, experts worry the virus is moving so fast it could mutate enough to allow humans to pass it on to each other. If this happens, it could become a bigger health crisis than SARS, they have warned.
The WHO has said the virus needs to be taken out of the bird population so it doesn't jump to humans and to migratory birds, which could spread it further.
Humans have been infected only in Vietnam and Thailand, although officials in Cambodia said Monday (26. 01. 04) two boys who played with chickens are suspected of having the virus.
Genetic analysis of bird flu
Guangdong health authorities have attributed the disease to Mycoplasma pneumoniae. Beijing health authorities examined lung tissue from two dead patients and declared that the culprit was Chlamydia.
A closely related virus has, however, been found in wild ducks and egrets in Hong Kong in the past few months. "The virus comes from wild birds and could have come from anywhere.
Of the four types of influenza virus, only two trouble Homo sapiens. Most regional epidemics are due to type B. But human pandemics such as the notorious 1918 flu, said to have killed twice as many people as World War I, are caused by type A. These have avian lineages, according to Webster, author of a new flu review appearing in the March–April issue of American Scientist.
The flu virus is made up of eight RNA segments that code for at least 10 proteins; they can reassort easily when two viruses (even from different host species) infect the same cell. Type A viruses are classified by subtypes of their two cell-surface proteins, hemagglutinin and neuraminidase, which cause epidemics when they mutate in ways that permit them to evade the host immune system. The villain in the 1918 epidemic is known as H1N1. Both the 1997 bird flu and the new outbreak are examples of H5N1, although they are not identical (T. M Powledge, 2003).
Avian influenza (WHO)
Avian influenza is an infectious disease of birds caused by type A strains of the influenza virus. The disease, which was first identified in Italy more than 100 years ago, occurs worldwide. All birds are thought to be susceptible to infection with avian influenza, though some species are more resistant to infection than others. Infection causes a wide spectrum of symptoms in birds, ranging from mild illness to a highly contagious and rapidly fatal disease resulting in severe epidemics. The latter is known as “highly pathogenic avian influenza”. This form is characterized by sudden onset, severe illness, and rapid death, with a mortality that can approach 100%.
Fifteen subtypes of influenza virus are known to infect birds, thus providing an extensive reservoir of influenza viruses potentially circulating in bird populations. To date, all outbreaks of the highly pathogenic form have been caused by influenza A viruses of subtypes H5 and H7. Migratory waterfowl – most notably wild ducks – are the natural reservoir of avian influenza viruses, and these birds are also the most resistant to infection. Domestic poultry, including chickens and turkeys, are particularly susceptible to epidemics of rapidly fatal influenza.
Direct or indirect contact of domestic flocks with wild migratory waterfowl has been implicated as a frequent cause of epidemics. Live bird markets have also played an important role in the spread of epidemics.
Recent research has shown that viruses of low pathogenicity can, after circulation for sometimes short periods in a poultry population, mutate into highly pathogenic viruses. During a 1983–1984 epidemic in the United States of America, the H5N2 virus initially caused low mortality, but within six months became highly pathogenic, with a mortality approaching 90%. Control of the outbreak required destruction of more than 17 million birds at a cost of nearly US$ 65 million. During a 1999–2001 epidemic in Italy, the H7N1 virus, initially of low pathogenicity, mutated within 9 months to a highly pathogenic form. More than 13 million birds died or were destroyed.
The quarantining of infected farms and destruction of infected or potentially exposed flocks are standard control measures aimed at preventing spread to other farms and eventual establishment of the virus in a country’s poultry population. Apart from being highly contagious, avian influenza viruses are readily transmitted from farm to farm by mechanical means, such as by contaminated equipment, vehicles, feed, cages, or clothing. Highly pathogenic viruses can survive for long periods in the environment, especially when temperatures are low. Stringent sanitary measures on farms can, however, confer some degree of protection.
In the absence of prompt control measures backed by good surveillance, epidemics can last for years. For example, an epidemic of H5N2 avian influenza, which began in Mexico in 1992, started with low pathogenicity, evolved to the highly fatal form, and was not controlled until 1995.
A constantly mutating virus: two consequences
All type A influenza viruses, including those that regularly cause seasonal epidemics of influenza in humans, are genetically labile and well adapted to elude host defenses. Influenza viruses lack mechanisms for the “proofreading” and repair of errors that occur during replication. As a result of these uncorrected errors, the genetic composition of the viruses changes as they replicate in humans and animals, and the existing strain is replaced with a new antigenic variant. These constant, permanent and usually small changes in the antigenic composition of influenza A viruses are known as antigenic “drift”.
Influenza viruses have a second characteristic of great public health concern: influenza A viruses, including subtypes from different species, can swap or “reassort” genetic materials and merge. This reassortment process, known as antigenic “shift”, results in a novel subtype different from both parent viruses. As populations will have no immunity to the new subtype, and as no existing vaccines can confer protection, antigenic shift has historically resulted in highly lethal pandemics. For this to happen, the novel subtype needs to have genes from human influenza viruses that make it readily transmissible from person to person for a sustainable period.
Conditions favourable for the emergence of antigenic shift have long been thought to involve humans living in close proximity to domestic poultry and pigs. Because pigs are susceptible to infection with both avian and mammalian viruses, including human strains, they can serve as a “mixing vessel” for the scrambling of genetic material from human and avian viruses, resulting in the emergence of a novel subtype. Recent events, however, have identified a second possible mechanism. Evidence is mounting that, for at least some of the 15 avian influenza virus subtypes circulating in bird populations, humans themselves can serve as the “mixing vessel”.
Human infection with avian influenza viruses: a timeline
Avian influenza viruses do not normally infect species other than birds and pigs. The first documented infection of humans with an avian influenza virus occurred in Hong Kong in 1997, when the H5N1 strain caused severe respiratory disease in 18 humans, of whom 6 died. The infection of humans coincided with an epidemic of highly pathogenic avian influenza, caused by the same strain, in Hong Kong’s poultry population.
Extensive investigation of that outbreak determined that close contact with live infected poultry was the source of human infection. Studies at the genetic level further determined that the virus had jumped directly from birds to humans. Limited transmission to health care workers occurred, but did not cause severe disease.
Rapid destruction – within three days – of Hong Kong’s entire poultry population, estimated at around 1.5 million birds, reduced opportunities for further direct transmission to humans, and may have averted a pandemic.
That event alarmed public health authorities, as it marked the first time that an avian influenza virus was transmitted directly to humans and caused severe illness with high mortality. Alarm mounted again in February 2003, when an outbreak of H5N1 avian influenza in Hong Kong caused 2 cases and 1 death in members of a family who had recently travelled to southern China. Another child in the family died during that visit, but the cause of death is not known.
Two other avian influenza viruses have recently caused illness in humans. An outbreak of highly pathogenic H7N7 avian influenza, which began in the Netherlands in February 2003, caused the death of one veterinarian two months later, and mild illness in 83 other humans. Mild cases of avian influenza H9N2 in children occurred in Hong Kong in 1999 (two cases) and in mid-December 2003 (one case). H9N2 is not highly pathogenic in birds.
The most recent cause for alarm occurred in January 2004, when laboratory tests confirmed the presence of H5N1 avian influenza virus in human cases of severe respiratory disease in the northern part of Viet Nam.
Why H5N1 is of particular concern
Of the 15 avian influenza virus subtypes, H5N1 is of particular concern for several reasons. H5N1 mutates rapidly and has a documented propensity to acquire genes from viruses infecting other animal species. Its ability to cause severe disease in humans has now been documented on two occasions. In addition, laboratory studies have demonstrated that isolates from this virus have a high pathogenicity and can cause severe disease in humans. Birds that survive infection excrete virus for at least 10 days, orally and in faeces, thus facilitating further spread at live poultry markets and by migratory birds.
The epidemic of highly pathogenic avian influenza caused by H5N1, which began in mid-December 2003 in the Republic of Korea and is now being seen in other Asian countries, is therefore of particular public health concern. H5N1 variants demonstrated a capacity to directly infect humans in 1997, and have done so again in Viet Nam in January 2004. The spread of infection in birds increases the opportunities for direct infection of humans. If more humans become infected over time, the likelihood also increases that humans, if concurrently infected with human and avian influenza strains, could serve as the “mixing vessel” for the emergence of a novel subtype with sufficient human genes to be easily transmitted from person to person. Such an event would mark the start of an influenza pandemic.
Influenza pandemics: can they be averted?
Based on historical patterns, influenza pandemics can be expected to occur, on average, three to four times each century when new virus subtypes emerge and are readily transmitted from person to person. However, the occurrence of influenza pandemics is unpredictable. In the 20th century, the great influenza pandemic of 1918–1919, which caused an estimated 40 to 50 million deaths worldwide, was followed by pandemics in 1957–1958 and 1968–1969. Experts agree that another influenza pandemic is inevitable and possibly imminent.
Most influenza experts also agree that the prompt culling of Hong Kong’s entire poultry population in 1997 probably averted a pandemic.
Several measures can help minimize the global public health risks that could arise from large outbreaks of highly pathogenic H5N1 avian influenza in birds. An immediate priority is to halt further spread of epidemics in poultry populations. This strategy works to reduce opportunities for human exposure to the virus. Vaccination of persons at high risk of exposure to infected poultry, using existing vaccines effective against currently circulating human influenza strains, can reduce the likelihood of co-infection of humans with avian and influenza strains, and thus reduce the risk that genes will be exchanged. Workers involved in the culling of poultry flocks must be protected, by proper clothing and equipment, against infection. These workers should also receive antiviral drugs as a prophylactic measure.
Clinical course and treatment of human cases of H5N1 avian influenza
Published information about the clinical course of human infection with H5N1 avian influenza is limited to studies of cases in the 1997 Hong Kong outbreak. In that outbreak, patients developed symptoms of fever, sore throat, cough and, in several of the fatal cases, severe respiratory distress secondary to viral pneumonia. Previously healthy adults and children, and some with chronic medical conditions, were affected. Tests for diagnosing all influenza strains of animals and humans are rapid and reliable. Many laboratories in the WHO global influenza network have the necessary high-security facilities and reagents for performing these tests as well as considerable experience. Rapid bedside tests for the diagnosis of human influenza are also available, but do not have the precision of the more extensive laboratory testing that is currently needed to fully understand the most recent cases and determine whether human infection is spreading, either directly from birds or from person to person.
Antiviral drugs, some of which can be used for both treatment and prevention, are clinically effective against influenza A virus strains in otherwise healthy adults and children, but have some limitations. Some of these drugs are also expensive and supplies are limited.
Experience in the production of influenza vaccines is also considerable, particularly as vaccine composition changes each year to match changes in circulating virus due to antigenic drift. However, at least four months would be needed to produce a new vaccine, in significant quantities, capable of conferring protection against a new virus subtype (WHO, 2004).
Here's some interesting information about the new flu strain in Hong Kong :
On May 11, 2003, a 3-year-old boy was hospitalized here with typical flu symptoms--acute fever, sore throat and raspy cough. Ten days later, the boy died of viral pneumonia and other complications.
Then something happened that has excited and frightened health officials around the world: A lab analysis found that the boy was infected with the same virus that killed the New Territories chickens--the first recorded case of a pure bird virus infecting a human being.
The remarkable discovery, which has been followed by at least three more cases here, one of them fatal, has scientists from around the world converging on Hong Kong and has spread alarm throughout the territory, where worried citizens are releasing caged pets and avoiding chicken in their diets.
One of humankind's greatest medical mysteries about how flu viruses mutate and grow, periodically circling the globe in deadly pandemics is now the challange.
- First jumped "species barrier" from bird to human in 1997 In humans, similar symptoms include fever, sore throat, and cough Types known to infect humans are influenza A subtypes H5N1 and H9N2
- Fever, body ache and headache just like with other types of flu
- Will quickly turn into a severe respiratory disease
- May feature convulsion-like shivering
- Respiratory failure as lead to death in a high percentage of diagnosed cases
- People who work in poultry farms and/or handle poultry droppings are at the greatest risk, along with their families
- No risk from eating cooked chicken meat
- Human-to-human transmission not yet found
- Livestock handling should be done wearing face masks
- Any suspected flu in birds should be taken seriously; if proven, the livestock should be buried or burnt immediately
- Persons handling poultry stock developing flu-like symptoms should seek immediate medical support
The two viruses could combine to produce a hybrid that was both highly pathogenic and transmissible between humans. Such viruses are thought to have caused pandemics in the past.
It is not known whether the virus is being carried around by wild birds, which are monitored for flu in Europe and North America but not so far in Asia. Normally flu viruses form a reservoir in ducks - but this strain of H5N1 virus kills ducks, a shift in virulence that has unsettled virologists. However, Thompson (WHO, Switzerland ) notes that the avian virus is not transmitted very efficiently to humans: "There could be a million birds or more in Vietnam that have the disease or have had the disease, and yet we have just a handful of [human] cases."
The German Government is Concerned that Bird Flu Will Reach Germany
The German authorities said on Thursday it was concerned bird flu could spread to the country and announced new measures to deal with the threat. The Netherlands has been battling an outbreak of the disease since the beginning of March. Although some 11 million birds have been slaughtered there since the crisis began, new Dutch cases are still being discovered. "We have great concern that bird flu could spread to Germany," German junior Agriculture and Consumer Protection Minister Alexander Mueller said in a statement. "The latest suspected case in the Netherlands is only three kilometres from the German border."More than nine million chickens have been slaughtered on 800 farms in the eastern Dutch province of Gelderland to prevent the disease spreading since the outbreak began in late February. The Dutch agricultural ministry said on Friday that the outbreak has now likely spread to farms in two additional areas, one in the southeastern province of Limburg, and one in the southern province of North Brabant.
Before the outbreak, the Netherlands was home to more than 100 million chickens, more than six chickens per inhabitant. Dutch exports of fowl and poultry products have been stopped since the start of the outbreak, which is believed to have been caused by contact between wild ducks and farm poultry. The outbreak has so far cost farmers and the government an estimated EUR100 million."
BIRD FLU KILLS VETRINARIAN
April 20, 2003 -- AMSTERDAM - A Dutch veterinarian has died of pneumonia after catching the poultry disease bird flu, officials said yesterday, raising fears that a mutated version of the virus could cause a SARS-type epidemic in people. The 57-year-old man died on Thursday in the southern city of Den Bosch, the Health Ministry said. He fell ill two days after working on a farm infected with bird flu, or avian virus. The World Health Organization has warned that the disease could turn into a human epidemic.
So far, 82 people with clinical symptoms have tested positive for the bird virus. Nearly all have had conjunctivitis, a mild eye infection, but six people had typical flu-like symptoms. Worryingly, there has been "strong evidence" that three of these cases did not catch the virus from sick poultry, but from a family member working on infected poultry farms, says Ron Fouchier of Erasmus University in Rotterdam. One was a 12-year-old child with classic flu symptoms (NewScientist, April, 2003).
Virologists at Erasmus University say the virus is an H7N7 type of influenza A, named for the variants of two proteins on its surface. Exact gene sequences show it is a recombinant of two viruses recently sampled in wild Dutch ducks. A subsequent mutation seems to have occurred after the virus invaded chickens, causing the virus to become the Netherlands' first highly pathogenic strain.
"We absolutely do not want to see human flu evolve from the avian virus," says Albert Osterhaus, of Erasmus University, Rotterdam. "If a human virus emerged with surface proteins from the avian virus, there would be no antibodies to it in the population" (New scientist, March 2003).
When the avian flu was first detected on a poultry farm in Gelderland province at the beginning of March, Health Minister Clemence Ross-Van Dorp and Agriculture Minister Cees Veerman said the risk to humans was "negligibly small". But evening newspaper NRC reported on Thursday that since then a total of 82 people including five vets, involved in the massive culling operation at poultry farms have contracted the avian flu virus H7N7. The majority, 79, only have conjunctivitis (an eye infection) and in three cases the condition was transferred from human to human. ( Expatica News, 2003)
According to our most recent information, there are now 7 confirmed outbreaks and one farm is under suspicion. The farm under suspicion is situated in Loenhout in zone 2, approx. 3 kilometers from the affected farm in Meer. 5 of the confirmed cases are situated in the northeastern corner of Belgium. The two remaining confirmed cases as well as the suspected one is situated east-northeast of Antwerp at the Dutch border and close to a Dutch region where there is so far no outbreak of AI.
Bangladesh Unable to Indentify Bird-flu Virus10 Asian countries hit by the rapid spread of bird flu that has killed at least eight people and threatens to develop into an epidemic worse than SARS Experts have pointed out that Bangladesh is not prepared to face a quick spread of the disease. We can test whether a suspect is bird flu-positive or-negative, but we have no way of detecting the virus. The international agencies working in this area, especially the World Health Organisation, have made it known that development of a vaccine to combat the disease may take a long time. So the task of coping with it has to be basically accomplished by the national governments at this stage.The country does not import chicks, but that alone hardly guarantees our safety since the infected broilers may enter the country through different points. So strict surveillance is needed to keep things under control. In this case, we are not getting much help from the international organisations, except the warning that Bangladesh is among the vulnerable countries.
"We may be in danger if bird flu spreads in neighbouring India or Myanmar. We have taken all-out measures to check import of poultry or poultry products from East Asian countries," said a top-ranking official of Bangladesh Livestock Research Institute (BLRI). "The only facility we now have is that we can only identify bird-flu positive or negative poultry. We don't have expertise to identify the virus or tackle the problem. But we are trying to be well prepared on an urgent basis," the official said.
The prices of poultry, including day-old birds, broilers and other chickens, have slid in weeks. "Our sells have dived as people are less interested in chickens because of the virulent virus," a retailer at Karwan Bazar told this correspondent yesterday. The retail price has dropped to Tk 50 a kg from Tk 60 two weeks ago.Broiler now sells at Tk 35 a kg on the wholesale market, down from Tk 55 a kg two weeks ago.
A Recent outbreak of bird flu in Vietnam, South Korea, Japan, Thailand, Cambodia and lately Pakistan has killed billions of chicken and there are reports of its human transmission killing at least 10 people till January 27. “The deadly flu has left doctors suspicious and we are following all reports of poultry deaths and any related human flu,” said a professor of medicine at the Dhaka Medical College Hospital (DMCH).
Death of poultry birds:Farm owners panicky, cause not detected
GAZIPUR, Jan 28, 2004:–Large-scale death of poultry birds in the district made the farm owners panicky as the reason behind the death is yet to be detected, reports UNB. According to local sources, poultry birds started dying for the last few days after the farm owners vaccinated their chicken with RDV vaccine. They brought the vaccine from the district Livestock Office for ‘Ranikhet’ disease.
Veterinary Hospital under the Livestock Department has already conducted postmortem of 12 poultry birds. The postmortem report said septic infection of legs from vaccination might be causing the fatalities. Meanwhile, District Livestock Officer asked the poultry owners not to inject those vaccines to the poultry birds, which were earlier given. He also requested the hatchery owners not to import chicks from abroad and not to allow the poultry disease experts, coming from bird flu affected countries, in their farms.
A three-member emergency team was formed to monitor the disastrous situation. According to an estimate by the Livestock Department, nearly 6,000 birds of 11 farms in the district died till Monday.
Bangladesh is at extreme risk
Bangladesh is at extreme risk because India, a high-prevalence country, surrounds it. In India 30,000 chickens were found to have died from the virus. Susceptible birds become infected when they have contact with contaminated secretions or excretions, or with surfaces that are contaminated with secretions or excretions, from infected birds. The H5N1 virus is transmitted from one affected poultry farm to another. People, vehicles, and other non-living objects such as cages can be vectors for the spread of the virus from one farm to another.
Bangladesh must not adopt a complacent attitude in this respect as this country has all the determinants for an explosive outbreak of bird flu epidemic. As Bangladesh consists of Wetlands, it engages hundreds and thousands of migratory birds. Therefore Bangladesh is exposed to a risk. The healthcare system is inadequate and overstrained and living is extremely crowded, especially is Dhaka. If the bird flu enters Bangladesh, it will spread like fire. We still have time for caution and vigilance
Measure to be taken
It is important to increase awareness of the health care staff of the characteristic symptoms and facilitate medical attention. Vigilance has to be strengthened at all ports and borders. Travelers with bird flu symptoms have to be screened or quarantined. All travelers or visitors from affected countries should have health declaration papers.
The BDR border guards shall be extra vigilant to prevent the smuggling of live birds or poultry products from neighbouring countries. Similar awareness building campaign needs to be started through the media. Arrangement should be made for massive vaccination of poultry birds. Additionally, we need to set up facilities for diagnosing this virus in various diagnostic laboratories as soon as possible.
The screening centre at the Zia International Airport must clear all travelers arriving from bird flu-affected countries before entering Dhaka. Bangladesh has already banned the import of live chickens from seven East Asian countries because of fears about bird flu. We need to have separate hospital and technical assistance to combat this deadly disease. It is not only quarantining but the entire building, clinic or health facility -- in which the patient along with the persons who came in contact with the patient are lodged -- has to be sealed off for a certain period.
Some scientists suggested that the Bangladesh Health Ministry should have stocks of drugs such as Relenza, or Tamiflu. Farmers who raise ducks in the wetlands need to safeguard their birds from getting contacted with migratory birds by using nets.
According to the studies by the World Health Organization on avian influenza outbreaks in other regions, backyard farming was the source in many cases. Due to space constraints, backyard poultry owners could not install bio-security measures to prevent cross infection. Industrial poultry practices needs to be taken very seriously. It was found that in China and South Asia, the main vector is the transnational poultry industry.
No government must ignore the threat of avian influenza. Instead, all are racing against time to prevent any occurrence of human infection cases. It is a matter of fact that backyard poultry and transnational poultry keeping activities have posed an immediate and serious threat to the public health in Hong Kong as well other countries (Shakeeel Ahmed Ibne Mahmood, March 23, 2007).
Experts believe the unknown virus that killed 19 people, mostly children, in three districts in the last two weeks is under control, as mystery disease patients are recovering fast and no new case was reported yesterday. "The disease is in check. Patients are recovering with supportive treatment alone," Dr MA Faiz of Dhaka Medical College Hospital (DMCH) said, confirming the disease only as viral infection without establishing an immediate link to the bird flu virus that has broken out in much of Asia.
The disease that causes high fever, headache, vomiting and spells of unconsciousness has stalked some villages in Rajbari, Manikganj and Tangail in Bangladesh.
Why are we still in the dark about it? After SARS it is the Asian bird flu that has set off alarm bell to health authorities in Asia. Viruses from the blue are wreaking havoc on human lives throwing formidable challenges to find antidotes to them. Times are bad, putting epidemiology to the severest of tests. No sooner had one unknown viral attack been contained another followed suit.
Against this backdrop, a mystery disease has taken a toll of 19 souls, mostly children, in Rajbari, Manikganj and Tangail. The fatalities have occurred over the last two weeks. But the patients are said to be recovering 'with supportive treatment alone', meaning use of antibiotic and antiviral medicines. No immediate link is established to bird flu but what is important to note is that we do not have adequate equipment to identify the virus or diagnose the disease.
We are, of course, quarantining the patients and reportedly they are recovering through the administration of standard procedures. But have we woken up to the stupendous challenges of new viral infections that defy borders, however impregnable these might have been thought of? (The Daily star, Editorial, January 28, 2004.
A five-member team from the Centre for Disease Control, Atlanta, USA, and the WHO headquarters in Geneva is expected to reach the country on February 4 to investigate into the outbreak and to detect the virus. “They, in all likelihood, will bring the necessary equipment with them for the purpose. At present the country has no expertise to identify the cause,” a health directorate official said (New Age, February 1, 2004).
Agri quarantine in quandary in Bangladesh
Quarantine centres under the Department of Agriculture Extension (DAE) are allegedly issuing indiscriminate import permission certificates and release orders for import consignments of all kinds of agricultural products, irrespective of whether they are of banned varieties or not. Sources in the DAE have told New Age that some officials at the plant quarantine centres in Dhaka, Benapole, Darsana, Chittagong seaport, Bhomra and Hili, including some service centres, are issuing import certificates and release orders to such imports disregarding the obligatory examination of the plants.
While the rat of corruption can be smelt all over, the indiscriminate importation of agricultural plants and products can pose long-term harm to the agricultural sector, the agro-based industry now being a thrust sector of the economy. It is further alleged that some officials of the DAE are issuing the phyto-sanitary certificates without any examination of the products or inspection at the end of exporters' godowns
This examination is absolutely necessary under the WTO regime, or even before it by individual countries of the west, in order that the exportable food or agricultural products are absolutely hygienic and fit for human consumption, and hence for export. Several times in the immediate past or even before, export consignments of frozen food, agricultural products and fruits were rejected by the importing country and the consignments returned for not being properly tested in laboratories.
The Ministry of Agriculture did not take punitive action against the parties involved. Three years ago, some consignments of potato and vegetables to England were detected to carry germs injurious to human health. The shipments were cancelled and the consignments were sent back to the country. Most of the officials working at different quarantine centres usually are not present at their respective offices and consequently most of the consignments of the goods are frequently released without any tests, whereas the quarantine is an emergency service supposed to be open and at work round the clock.
The quarantine laboratories, on the other hand, are also not in working order as most of the equipments have gone into obsolescence or are in disrepair.
In the case of imported products, importers have to pay an additional amount of money for taking their permission certificate and simultaneously in getting the release order for the imported goods. Those go without tests, but nevertheless are released. Quarantine centres across the country are to oversee and test the imported products in order to rigorously ensure through bio-chemical tests that those are free from germs or diseases. Bangladesh imports all kinds of agricultural products like rice, wheat, daal, cotton, varieties of fruits, saplings without soil and all kinds of spices from different countries.
A DAE entomologist said that the quarantine centres are not properly upgraded as the government alone could not do enough to bear all the necessary costs of proper maintenance ( New Age, February 6, 2004)..
Poultry feed churned out from tannery waste
Last Modified January 25, 2008
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