Introduction
Following anecdotal reports of die-offs of birds in January 2006, influenza
A/H5N1 virus infection was confirmed in February 2006 by the State
Veterinary Laboratory in Baku in samples obtained from wild birds,
commercial poultry (chickens), and backyard poultry (ducks) in central
and south Azerbaijan [1]. However, there was reportedly no extensive
spread through backyard poultry in the villages. The Republic of Azerbaijan,
with approximately 8.4 million inhabitants [2], lies on the shore of
the Caspian Sea in the Caucasus, bordering the Russian Federation,
Georgia, Armenia, Turkey, and Iran. As common in the whole subregion,
migratory birds fly through Azerbaijan twice each year, from Siberia
to Africa in the autumn (August-December) and back in the spring (February-May)
[3].
On 6 March 2006, the Ministry of Health (MoH) of the Republic of Azerbaijan
reported to the World Health Organization (WHO) Regional Office for Europe
a cluster of nine cases, including two deaths, of potential human influenza
with influenza A/H5N1 HAI [4]. The patients had become ill over a two
week period, with dates of illness onset from 15 February to 4 March
2006, and lived in Daikyand settlement in Salyan district, 130 km southeast
of the capital, Baku [FIGURE]. Their symptoms included fever, headache,
cough and meningeal signs. The clinical presentation was varied, which
may have obscured and delayed the suspicion of influenza A/H5N1 virus
infection.
On 9 March 2006 another pair of cases where influenza A/H5N1 virus infection
was suspected was reported to the MoH from Bayim-Sarov, Tarter district
in central eastern Azerbaijan. The date of illness onset of the first
case was 28 February 2006 and was initially diagnosed with reactivation
of tuberculosis (TB). Because of this diagnosis, influenza A/H5N1 virus
infection was only considered when the second patient became ill on
4 March 2006.
On 15 March 2006, further to a request for assistance by the MoH, a WHO-led
international team that had been in Azerbaijan since 5 March 2006 to
support the implementation of the national surveillance system for HAI
was strengthened by experts in infection control, clinical management,
epidemiology, laboratory work and communication. The team, which eventually
comprised 11 individuals representing five institutions and organisations
(Robert Koch-Institut, Germany; Státní Zdravotní Ústav – Centrum
Epidemiologie a Mikrobiologie, Czech Republic; US NAMRU-3, Egypt; WHO
Headquarters, Switzerland; WHO Regional Office for Europe, Denmark),
was deployed in order to assist in
(i) describing the outbreak;
(ii) public health surveillance, including active case-finding;
(iii) timely and accurate laboratory diagnosis of influenza A/H5 virus
infection;
(iv) safe and effective case management and transport of patients for
whom influenza A/H5N1 virus infection was considered.
Methods
Surveillance system, case finding and case investigation
In accordance with national ministerial decrees issued early in 2006,
district chief doctors implemented reporting of cases where influenza
A/H5N1 virus infection was suspected from the local doctors to the MoH
and informed and trained healthcare workers on how to detect and report
such cases. All reported cases were investigated at district level and,
after reporting to the central level, also by the MoH-WHO response team.
Since early February 2006, the general public was also informed, through
social mobilisation campaigns (e.g. distribution of posters, school lessons)
at district and national level, about the risk of exposure to and mode
of transmission of influenza A/H5N1 virus, symptoms of AI, and was invited
to seek medical care if suggestive symptoms developed.
Daily active surveillance for human cases of influenza A/H5N1 virus infection
began on 1 March 2006 in Daikyand settlement. A total of four brigades,
each comprising three local healthcare workers, made daily visits to
all households (200 households per brigade) to screen residents for fever
or respiratory symptoms, through interviews and direct observation. Surveillance
data were reported daily by the chief district doctors to the MoH. A
similar system became operational in Tarter district around mid-March
2006.
The surveillance team, which included members from the MoH, the Anti-Plague
Station (APS), the Republican Centre of Sanitary Hygiene (both technical
institutions reporting to the MoH), and WHO, developed a case definition
[see Box] and a standardised case investigation form for potential HAI
cases, including the following sections: reporting and demographic details,
clinical presentation and evolution, history of admission to healthcare
facilities, assumption of antiviral drugs as prophylactic or/and treatment
measures, history of exposure to animal and human cases, laboratory test
results for influenza A/H5N1 virus, final disposition. Both the case
definition and the case investigation form were translated into the languages
used locally (Azeri and Russian) and used across the country. Data on
cases were gathered from multiple sources, including medical records,
district medical officers and epidemiologists and directly by interview
from family members. When necessary, the interviewing was repeated to
collect all the relevant information as further intelligence came to
light.
Forms for the monitoring of healthcare workers and workers in the veterinary
sector, as well as for contact persons, were developed and an Epi Info
2000 database was created in English and Russian for data entry and analysis.
Box
Case definition of influenza A/H5N1
Possible case
• any individual with unexplained axillary temperature ?38 °C;
• AND one or more of the following symptoms: cough, sore throat, shortness
of breath;
• AND resident in an area where influenza A/H5 virus infection has been
suspected (i.e. undiagnosed mass poultry die-offs, dead wild birds seen or probable/confirmed
human cases from the area).
Probable case
a possible case AND that had, within 7 days prior to the onset of
symptoms, one or more of the following:
• close contact (within 1 metre) with a probable or confirmed case;
• close contact with sick or dead poultry or with areas heavily contaminated
by their droppings;
• close contact with wild birds or with areas heavily contaminated by their
droppings;
• consumption of undercooked bird meat or eggs;
• worked in laboratory processing samples (human or animal) suspected of
containing influenza A/H5 influenza virus.
Confirmed case
• a probable case for whom a specimen tested positive for influenza A/H5
virus infection by PCR.
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Laboratory methods
National laboratory capacity was established using a portable field laboratory
was established at the APS premises in Baku by the United States Naval
Medical Research Unit 3 (NAMRU-3), Cairo (Egypt). The field laboratory
included real-time polymerase chain reaction (RT-PCR) with capacity
to detect influenza A/H5 virus. All clinical specimens were tested
for the presence of influenza A/H5 virus infection using a two-step
procedure, involving testing for ‘flu A (matrix gene)’ followed
by a second round for H5. No serological tests were performed at the
field laboratory.
Regardless of the results obtained in the field, all specimens were transferred
to the WHO Collaborating Centre for Influenza at the National Institute
for Medical Research (NIMR), Mill Hill (United Kingdom) for confirmation
by RT-PCR for influenza A/H5 virus (Asian lineage), haemagglutination
inhibition test, virus isolation in embryonated eggs and MDCK cells,
and genomic sequencing.
Results
Epidemiology
Cluster 1
Daikyand is a rural, relatively poor village in Salyan district, with
around 4800 inhabitants in 800 households. The village is divided in
three settlements: Seydler, Daikyand and Salvan [FIGURE].
Influenza A/H5 infection was laboratory confirmed in samples from seven
residents of Daikyand settlement. Six were from the same family and one
from a neighbouring family, and became ill over a two week period, with
dates of onset from 15 February to 4 March 2006. Four of the seven cases
died, and this figure is compatible with the case fatality rate observed
elsewhere [5]. The median interval between onset of symptoms and death
was 9 days (mean: 11.2 days; range: 8–19 days). Patients’ ages
ranged from 10 to 20 years (mean: 16 years; median: 17 years); five of
the seven cases were females aged 15– 20 years.
During the initial interviews, family members denied any contact with
sick or dead wild birds or domestic poultry. However, other community
members indicated that in February 2006 a massive die-off of swans had
occurred in the area and that the family might have had contact with
the swans. Following further repeated interviews, relatives of the cases
finally revealed that, in February 2006, the family had been involved
in de-feathering dead wild swans.
Among the seven cases, the signs and symptoms reported included fever
(six), pneumonia (six) cough (five), sore throat (four), shortness of
breath (one), stomach pain (one), body aches (one) and meningeal signs
(one). All seven cases were admitted to healthcare facilities in Baku
during the course of their illness; four were isolated in designated
facilities.
Cluster 2
On 28 February 2006, a 24 year old male resident in a camp for internally
displaced persons in Bayim-Sarov, Tarter district, in central eastern
Azerbaijan, developed shortness of breath, weakness, headache, and
had a low grade fever (37.5 °C). As his clinical condition deteriorated,
he was admitted to hospital. The patient died on 3 March 2006 with
diagnosis of reactivated TB. No samples were conserved for examination
and the patient was retrospectively classified as a probable case.
On 4 March 2006, his 18 year old sister developed similar symptoms. On
9 March 2006, three days after referral to Baku, she died, with a diagnosis
of TB. However, because of the rapid course of her illness, HAI was suspected.
Blood obtained post-mortem tested positive for influenza A/H5 virus infection
by the NAMRU-3 field laboratory. These findings were later confirmed
at NIMR, Mill Hill (United Kingdom).
In February 2006, a die-off of wild birds had been observed in Tarter
district, with no reports of sick poultry in the area. Family members
denied that the two siblings had been exposed to sick or dead domestic
or wild birds. Information provided by community members, however, suggested
that the siblings had purchased a dead turkey that was thought to have
been ill, and then de-feathered it, prepared it and ate it.
Other districts
The MoH-WHO team visited other districts identified as being at risk
for HAI because of reports of die-offs of birds or laboratory confirmation
of influenza A/H5 virus infection in wild birds or poultry. A total
of 22 individuals, including six deaths, were investigated for HAI
in six districts (Khachmaz, Neftchela, Tarter, Sabail, Salyan and Surakhana)
and admitted to healthcare facilities. The final case classification
includes eight confirmed cases and one probable case. Of the remaining
13 patients for whom HAI was considered, 12 tested negative for influenza
A/H5N1 virus infection and one, from whom no samples were obtained,
was diagnosed with another condition following thorough clinical assessment.
Laboratory
One hundred and eight clinical specimens (throat and nasal swabs, sera,
and rectal swabs) obtained from 20 individuals, in whom a diagnosis
of influenza A/H5N1 virus infection was considered and from 32 of their
contacts were tested by RT-PCR.
The field laboratory detected seven cases of influenza A/H5 virus infection
and NIMR confirmed eight cases. Of the three specimens (throat swabs)
that tested negative at the field laboratory and positive at NIMR, two
were from patients from whom additional specimens were obtained and subsequently
tested positive at the field laboratory. The throat swabs were taken
very early in the course of their illness and the viral load was likely
to be low. These results are compatible with the lower sensitivity of
tests performed by the field laboratory compared to that of tests performed
at the WHO Collaborating Centre for Influenza. All positive results obtained
by the field laboratory were confirmed by NIMR. No specimens from contacts
of patients tested positive for influenza A/H5 virus infection.
Virus strains were isolated from three cases from the cluster in Salyan
district. Phylogenetic comparison of H5 haemagglutinins at the WHO Collaborating
Centre for Influenza shows that all genes were of avian virus origin
and closely related to the sequences of the corresponding genes of other ‘Qinghai
Lake’ H5N1 viruses isolated from avian species (including viruses
isolated from a swan in Azerbaijan in February 2006, A/swan/Italy/179/06,
and from a swan in the Islamic Republic of Iran, A/swan/Iran/754/2006,
and from humans (in Turkey, Iraq and Egypt)) [6,7]. These viruses were
thus distinguishable from the H5 haemagglutinin of viruses isolated in
East Asian countries, including China, Indonesia and Vietnam.
Case Management
Clinical care at the regional level is limited in Azerbaijan, and mechanical
ventilation is generally not available at district hospitals. Therefore,
16 individuals for whom diagnosis of influenza A/H5N1 virus infection
was considered were transferred to three designated AI referral hospitals
in Baku. Patients fulfilling the definition of a probable case following
the clinical assessment were admitted to an isolation unit at one of
these hospitals. Probable and confirmed cases received oseltamivir
(150 mg/day for 5 days), antibiotic and critical care support as needed.
Severe cases were given oseltamivir up to 10 days, in accordance with
WHO advice [8]. Contacts of confirmed and probable cases, including
healthcare workers, were subject to health monitoring by the surveillance
teams or in the referral hospitals for seven days after the date of
their last known contact. None of the contact persons monitored developed
symptoms compatible with HAI.
Discussion
Between February and March 2006, two clusters of HAI with nine cases
(eight confirmed and one probable) were identified in Azerbaijan.
The majority of patients developed respiratory symptoms, with the exception
of one patient where meningeal signs were predominant, as already observed
in Vietnam [9]. Severe hypoxia, caused by the prolonged course of viral
pneumonia, appeared to be under-recognised and treated late in children.
The early establishment of oxygen saturation monitoring and provision
of continuous oxygen therapy is therefore crucial to prevent decompensation
and multi-organ failure already observed in cases of influenza A/H5N1
infection elsewhere [10].
Close contact with and de-feathering of infected wild swans were the
most plausible exposures to influenza A/H5N1 virus in the Daikyand cluster,
although the investigation of the possible source of infection was made
difficult because hunting and trading wild birds and their products is
illegal, and therefore there was some reluctance in the community affected
to disclose information on possible exposures. Repeated interviews of
relatives of the cases finally revealed that, in February 2006, all cases
had been involved in de-feathering dead wild swans, after a massive die-off
of swans had occurred in the area. Swan feathers are used for pillows
and can be sold at a good price in the locality. De-feathering birds
is often undertaken by women, which explains the predominance of female
cases [10,11].
The HAI cluster in Daikyand settlement is the first event where wild
birds were the most likely source of influenza A/H5N1 virus infection
in humans. However, the difficulties in gathering accurate information,
confusion over reported dates of illness onset, and similar experiences
with past influenza A/H5N1 outbreaks where multiple plausible exposures
were reported, mean that the possibility that limited human-to-human
transmission cannot be ruled out.
The economic implications associated with the ban of hunting and trading
in wild birds introduced in October 2006, and the fact that the issue
of financial compensation related to potential culling of backyard poultry
was not addressed in messages to the population may have hindered effective
collaboration with the community. Unfortunately, this might have influenced
the implementation of control measures as well as the investigation of
the source of infection. However, because of door-to-door surveillance
undertaken in Salyan and Tarter districts, it is unlikely that additional
HAI cases remained undetected.
The rapid establishment of the RT-PCR laboratory in Azerbaijan provided
timely and reliable diagnosis of influenza A/H5 virus infection close
to the outbreak site overcoming the difficulties of shipping procedures
to NIMR for confirmation which were not well established and subject
to delay. The specificity of the field laboratory RT-PCR was supported
by the absence of false-positive results.
The rapid mobilisation of resources to contain the spread of influenza
A/H5 in the two districts was possible because of the close and transparent
collaboration between the MoH, WHO and its international partners.
The risk of spread of HAI to western European countries by wild birds
is considered to be limited due to widespread awareness that sick and
dead wild birds are a potential source of influenza A/H5 virus infection
[12].
Note: this manuscript has been adapted from the following
WER publication: Human avian influenza in Azerbaijan, February-March
2006. Wkly Epidemiol Rec. 2005;81(18):183-8. http://www.who.int/wer/2006/wer8118.pdf
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