Avian influenza
Avian influenza – situation in Turkey – update 7 (30 January 2006)
A WHO collaborating laboratory in the United Kingdom has now confirmed 12 of the 21 cases of H5N1 avian influenza previously announced by the Turkish Ministry of Health. All four fatalities are among the 12 confirmed cases.
Samples from the remaining 9 patients, confirmed as H5 positive in the Ankara laboratory, are undergoing further joint investigation by the Ankara and UK laboratories.
Testing for H5N1 infection is technically challenging, particularly under the conditions of an outbreak where large numbers of samples are submitted for testing and rapid results are needed to guide clinical decisions. Additional testing in a WHO collaborating laboratory may produce inconclusive or only weakly positive results. In such cases, clinical data about the patient are used to make a final assessment.
Avian influenza – situation in Turkey – update 6 (18 January 2006)
Laboratory tests conducted at Turkey’s national influenza centre in Ankara have confirmed an additional case of human infection with the H5N1 avian influenza virus. The case is a 4-year-old boy from the district of Dogubayazit in Agri Province in the eastern part of the country. An outbreak in poultry began in the district in December 2005. The child developed symptoms on 5 January and was hospitalized on 13 January. He is being treated at a hospital in Erzurum Province.
Like the two cases confirmed on 16 January, also from Dogubayazit, exposure in this case occurred prior to the government’s launch of an intensive public education campaign. Rapid surveys conducted in the most severely affected eastern part of the country have found an almost universal awareness of the disease and of the risk factors for infection. This awareness has been accompanied by behavioural changes that are expected to reduce opportunities for human infections to occur.
As the virus is now known to be present in birds in many parts of the country, some additional human cases should be anticipated in the immediate future. The number of these cases is, however, expected to decline as high-risk behaviours become less common and culling operations, which are presently under way, reduce the number of infected birds.
The newly confirmed case brings the total in Turkey to 21. Of these cases, four were fatal. All four were residents of Dogubayazit.
A second shipment of laboratory specimens arrived yesterday at a WHO collaborating laboratory in the United Kingdom. Apart from providing diagnostic confirmation, the laboratory will undertake viral characterization and genetic and antigenic analyses of viruses. These studies help determine whether the virus is evolving. Antigenic analysis of the virus helps ensure that work on the development of a pandemic vaccine stays on track. Initial results are expected later this week.
Avian influenza – situation in Turkey - update 5 (16 January 2006)
Laboratory tests conducted at Turkey’s national influenza centre in Ankara have confirmed two additional cases of human infection with the H5N1 avian influenza virus. The first newly confirmed case is a five-year-old boy from the district of Dogubayazit in Agri Province in the eastern part of the country. He remains hospitalized in a stable condition.
His 14-year-old sister died on 15 January of a respiratory disease with clinical features similar to those seen in H5N1 infection. Test results received today have confirmed her infection.
As with all other cases seen in Turkey to date, both children developed illness following direct exposure to diseased poultry.
Ducks began dying in the family’s household flock on 1 January. On that day, the girl, assisted by her brother, slaughtered a duck for food. Both children developed symptoms on 4 January and both were hospitalized on 11 January. No other family members have developed signs of illness. These newly confirmed cases bring the total in Turkey to 20, of which four were fatal. Of the 20 cases, 18 have been children in the age range of four to 18 years.
A large number of patient samples have been sent to a WHO collaborating laboratory in the United Kingdom for verification of diagnosis and further analysis. WHO will adjust the number of cases and deaths in Turkey in its cumulative table of laboratory-confirmed cases upon receipt of results from the UK laboratory.
New outbreaks in birds continue to be reported across the country. To date, poultry outbreaks of highly pathogenic H5N1 avian influenza have been confirmed in 12 of the country’s 81 provinces. Outbreaks in an additional 19 provinces are under investigation.
Avian influenza – situation in Turkey - update 4 (12 January 2006)
Sequencing of human virus
Laboratory tests conducted in Turkey have confirmed detection of the H5 subtype of avian influenza virus in samples from an additional two patients. The patients are residents of Sanliurfa Province, near the southern border with Syria, and Siirt Province, which is adjacent to Van in the eastern part of the country. Human cases have now been reported from nine of the country’s 81 provinces.
Both patients are young children, aged four and six years, and both have a documented history of direct contact with diseased birds. In Sanliurfa Province, outbreaks in backyard poultry are now thought to date back to late November 2005. Altogether, agricultural officials have confirmed poultry outbreaks in 11 provinces and are investigating possible outbreaks in an additional 14 provinces across the country.
Laboratory tests completed today in Turkey have detected the H5 virus subtype in post-mortem specimens taken from a 12-year-old girl, from Agri Province, who died 7 January. The child was the sibling of two other patients who died earlier. Their infection with the H5N1 virus was subsequently confirmed by a WHO collaborating laboratory in the United Kingdom.
The Ministry of Health is now reporting 18 laboratory-confirmed cases, of which three, all from the same family, have been fatal.
Arrangements have been made to send specimens from several patients to the UK collaborating laboratory for further analysis. Due to official holidays in Turkey, specimens are not expected to arrive in the UK before Monday. The head of the collaborating laboratory is now in Ankara to support diagnostic work at the country’s national influenza centre. Ways are being sought to expedite the testing of patient samples. High awareness of the disease in the Turkish population, combined with almost daily reports of poultry outbreaks in new areas, has resulted in a large number of people concerned about exposure and seeking reassurance.
The rapid assessment of patients with a possible exposure history is providing a unique opportunity to learn more about the disease in humans. It is also generating data that can be used to assess the efficacy of antiviral drugs, as most people with an exposure history or respiratory symptoms are receiving oseltamivir either prophylactically or very early after the onset of symptoms.
Members of the international teams, in Van Province and Ankara, are today working with local experts to plan relevant studies. These studies should deepen understanding of the epidemiology of the disease, including the possibility that any human-to-human transmission may have occurred, the vulnerability to infection of health care workers and other occupationally-exposed groups, and the possibility that milder forms of the disease might be occurring in the general population.
All available evidence indicates that no sustained human-to-human transmission has occurred. As in Asia, contact with infected birds is the principal source of infection. The risk of infection for travellers to Turkey is negligible provided direct contact with dead or diseased domestic and wild birds is avoided.
Gene sequencing information on human viruses
The WHO Collaborating Centre for Reference and Research on influenza at the MRC National Institute for Medical Research in Mill Hill, London, has today completed genetic and antigenic analyses of viruses recovered from the first two fatal human cases in the Turkish outbreak.
Information provided to WHO indicates that these viruses are very similar to current avian H5N1 viruses isolated from birds in Turkey. They are also closely related to viruses isolated from the large outbreak in migratory birds that occurred at the Qinghai Lake nature reserve in China, beginning in late April of last year.
These analyses indicate that the Turkish viruses are sensitive to both classes of antiviral drugs, including oseltamivir and amantadine. WHO and collaborating experts will review the data on amantadine sensitivity. Oseltamivir remains the drug of first choice recommended by WHO.
Virus from one of the patients shows mutations at the receptor-binding site. One of the mutations has been seen previously in viruses isolated from a small outbreak in Hong Kong in 2003 (two cases, one of which was fatal) and from the 2005 outbreak in Viet Nam. Research has indicated that the Hong Kong 2003 viruses bind preferentially to human cell receptors more so than to avian cell receptors. Researchers at the Mill Hill laboratory anticipate that the Turkish virus will also have this characteristic.
Interpretation of the significance of this finding for human health will depend on clinical and epidemiological data now being gathered in Turkey.
All available evidence indicates that no sustained human-to-human transmission is occurring in any country experiencing human cases.
The present WHO level of pandemic alert remains at phase 3: human infections with a new virus subtype are occurring, but the vast majority of these infections are acquired directly from animals.
Avian influenza – situation in Turkey - update 3 (10 January 2006)
Tests conducted in Turkish laboratories have confirmed the country’s 15th case of human infection with the H5N1 avian influenza virus. The patient is a 37-year-old woman with a history of exposure to diseased chickens. She resides in the central province of Sivas, the seventh province to report cases. Although no poultry outbreaks have been officially reported in this province, it is located near areas with confirmed outbreaks in birds.
The situation in birds continues to evolve, with several new outbreaks under investigation in new parts of the country. All evidence to date indicates that patients have acquired their infections following close contact with diseased birds.
The Turkish government has launched an intensive public awareness campaign. Better public understanding of the disease, supported by more complete data on disease activity in birds, could help to reduce the risk of additional human cases, pending control of the disease in birds. As the majority of confirmed cases and persons under investigation are children, it is particularly important that messages about high-risk behaviours reach children.
Some 100,000 treatment courses of oseltamivir (Tamiflu) arrived in Turkey Friday evening. This supply, which is being used for both the treatment of patients and prophylaxis of persons at risk, is considered by Turkish health officials to be adequate for responding to the current situation. WHO has organized additional support for laboratory diagnostic work, and this will be arriving within the next day or two.
Dr Marc Danzon, the WHO Director for its European office, will be arriving in Ankara tomorrow to confer with the country’s Minster of Health. They will assess the situation together and review needs for further support.
Avian influenza – situation in Turkey - update 2 (9 January 2006)
Laboratory tests conducted in Turkey have confirmed detection of the H5 subtype of avian influenza virus in samples from an additional 10 patients. Five of these cases were announced by the Ministry of Health yesterday and an additional five were announced today. Most patients are children and all have been hospitalized for treatment and evaluation.
Of the five patients announced on Sunday, three are from Ankara Province and include two brothers, aged five and two years, and a 65-year-old man. All three patients are hospitalized in Ankara. The additional two cases, a nine-year-old girl and her three-year-old brother, are from the Dogubeyazit district in Agri Province, and are hospitalized in the city of Van.
The five cases announced today are from Kastamonu, Corum, and Samsun provinces, bordering the Black Sea in the north-central part of the country, and from Van Province.
This brings the total number of cases in Turkey, confirmed by laboratory tests there, to 14. Of these patients, two have died. WHO will add these numbers to its cumulative total following further verification by an external H5 reference laboratory.
The quality of laboratory testing at Turkey’s National Influenza Centre in Ankara is high. Results from tests conducted there last week were fully confirmed by a WHO collaborating laboratory in the United Kingdom. WHO considers it likely that test results on the newly announced cases will be confirmed by the UK laboratory, where samples are being sent for further analysis. H5N1 is the only strain within the H5 subtype known to infect humans. In the event of a confirmed H5N1 outbreak in birds, it is expected that human cases of avian influenza will be caused by the same virus strain.
The initial WHO team, accompanied by the Turkish Minister of Health, arrived in Van Province yesterday evening. The team is now investigating the epidemiological situation, assessing risk factors and control measures, and discussing with local authorities the possible need for additional equipment and supplies. The team will also be assessing patients at the Van hospital where some 38 people are currently being treated and evaluated for possible H5N1 infection.
The initial investigation has found no evidence that the virus has increased its transmissibility or is spreading from person to person. Most persons under investigation are children, often from the same family, and almost all have a documented link to dead or diseased poultry.
Outbreaks in poultry are now known to be occurring in several parts of the country. In recent days, the Ministry of Agriculture has confirmed H5N1 outbreaks in birds in 10 of the country’s 81 provinces. Extensive culling is under way, and several other possible outbreaks are under investigation.
With the agreement of the Ministry of Health, two epidemiologists and two experts in laboratory diagnosis will join the initial WHO team in the next few days. Given the present high level of awareness of the disease and its presence in poultry in several parts of the country, the number of people concerned about possible exposure is expected to increase. This additional support should expedite understanding of the epidemiological situation and increase the capacity to rapidly confirm or rule out persons under investigation for possible infection.
Avian influenza – situation in Turkey - update (7 January 2006)
The Ministry of Health in Turkey has confirmed an additional two cases of human infection with the H5N1 avian influenza virus. Both cases are children, aged five and eight years, and both are hospitalized. This brings the total number of laboratory confirmed cases in Turkey to four. Two of these cases were fatal.
A WHO collaborating laboratory in the United Kingdom has today confirmed detection of the H5N1 virus in samples taken from the two fatal cases.
The Ministry of Health has also announced a third death, presumably caused by the H5N1 virus, in a 12-year-old girl. The girl, who died on 6 January, is a sibling of the two children who died. A fourth child in the family, a six-year-old boy, is also hospitalized. Tests on samples from these patients are ongoing; neither is laboratory confirmed at present.
According to Turkish authorities, some 30 patients are being treated and evaluated for possible H5N1 infection at a hospital in Van Province. Most of the patients are children, and the majority come from the rural district of Dogubayazit.
Plans for a team of international experts to travel today to Van Province have been deferred because of adverse weather conditions. Government officials are assisting the team in finding a rapid mode of transportation to the affected area in the eastern part of the country.
To date, all evidence indicates that patients have acquired their infections following close contact with diseased poultry. Contact between people and poultry has likely increased during the present cold weather, when the custom among many rural households is to bring poultry into their homes. Tests have shown that the virus can survive in bird faeces for at least 35 days at low temperatures (4oC).
Based on experiences during the avian H5N1 outbreaks in Asia, behaviours that carry an especially high risk of infection include the slaughtering, defeathering, butchering, and preparation for consumption of diseased poultry. These behaviours tend to occur most frequently in rural areas where populations traditionally slaughter and consume birds once deaths or signs of illness are seen in poultry flocks.
In recent days, vigilance for outbreaks of the disease in poultry has increased considerably. Outbreaks of highly pathogenic H5N1 avian influenza have now been confirmed in six provinces in the eastern and south-eastern part of the country. Outbreaks at additional sites in the area are under investigation.
Avoidance of high-risk behaviours remains the most important way for local populations to protect themselves from infection.
Avian influenza – situation in Turkey (5 January 2006)
The Ministry of Health in Turkey has confirmed its first two cases of human infection with avian influenza caused by the H5 virus subtype. Both cases were fatal.
The first case was a 14-year-old boy from the rural district of Dogubayazit, in the eastern province of Agri, which borders the Islamic Republic of Iran and Armenia. He was hospitalized in Van Province on 1 January and died the same day. The second case was his 15-year-old sister, also hospitalized on 1 January. She died on 5 January.
Earlier this week, Turkish authorities had ruled out avian influenza in these cases based on preliminary test results from samples taken from the nose and throat. Subsequent tests of additional patient specimens taken from the lungs produced positive results. Patient samples were sent today to a WHO collaborating centre in the United Kingdom for further analysis. The samples have now arrived; results are expected within the next days.
Turkish health authorities have informed WHO that, since 1 January, a total of 11 patients (including the two confirmed fatal cases) have been hospitalized in Van Province with symptoms suggesting infection with avian influenza. Most patients are children between the ages of six and fifteen years and all reside in the Dogubayazit district. Two of the children are siblings of the two confirmed cases.
Following a request by the Ministry of Health, an initial team of experts from WHO, the European Centre for Disease Prevention and Control and the European Commission is travelling today to Turkey to collaborate with the authorities in their investigation of the situation.
Initial information about the confirmed cases suggests that the children acquired their infection following close contact with chickens. Deaths of chickens are known to have occurred in the Dogubayazit district near the end of last year. Although no poultry outbreak has been officially reported in the district, a confirmed outbreak of H5N1 avian influenza in chickens and ducks was reported on 27 December in the adjacent province of Igdir.
National authorities have informed WHO that Dogubayazit district has been placed under quarantine; no people or animals are allowed to move in or out of the district. Culling operations are currently under way.
The two Turkish cases mark the first confirmed reports of human infection with avian influenza outside East Asia. Since January 2004, a total of 142 human cases of H5N1 infection have been reported in Viet Nam, Thailand, Cambodia, Indonesia, and China. The cases in Turkey bring the number of affected countries to six, from which 144 cases have now been reported.
Turkey reported its first outbreak of H5N1 avian influenza in poultry in mid-October of last year. That outbreak, which occurred in the northwestern part of the country, was attributed to contact between domestic poultry and migratory waterfowl. The outbreak in Igdir and other suspected outbreaks in this part of the country are thought to have occurred following introduction of the virus by migratory birds. The region, which has several large lakes, is known to lie along migratory routes.