Avian influenza is a contagious infectious disease of birds caused via kind A lines of the influenza virus. The disease, which was once first identified in Italy in 1878, occurs worldwide amongst poultry populations. Birds are an extremely necessary species because all recognized subtypes of influenza A viruses circulate among wild birds, which might be thought to be the natural hosts for this variety of viruses.
Avian influenza is a contagious infectious disease of birds caused via kind A lines of the influenza virus. The disease, which was once first identified in Italy in 1878, occurs worldwide amongst poultry populations. Birds are an extremely necessary species because all recognized subtypes of influenza A viruses circulate among wild birds, which might be thought to be the natural hosts for this variety of viruses. However, avian influenza viruses typically don’t make wild birds ill, but can make domesticated birds very ill and often kill them.
This type of influenza isn’t typically known to infect humans, alternatively once transmitted the infection might result in construction of this disease with symptoms of avian influenza starting from conventional influenza-like signs (e.g., fever, cough, sore throat and muscle aches) to eye infections, pneumonia, acute breathing misery, viral pneumonia, and other critical and life-threatening complications.
Confirmed instances of avian influenza viruses infecting humans were reported since 1997 mainly a number of the South East Asian international locations known as the Hong Kong outbreak. All genes are of avian starting place, indicating that the virus has no longer acquired human genes. The acquisition of human genes is known to extend the likelihood that an epidemic of avian foundation can be readily transmitted from one human to every other.
The current epidemic was once first reported in October 2003 in Vietnam and is now known to spread to South Korea, Thailand and Laos and in some of these nations it has been reported to be brought about through the H5N1 pressure of Influenza Type numerous viruses. The World Health Organization (WHO) has reported that the H5N1 strain implicated within the outbreak has been sequenced. According to the most recent figures supplied by way of the WHO, that there have been 15 reported laboratory-confirmed circumstances of H5N1 pressure in Vietnam,11 of which were fatal. five circumstances have been reported from Thailand with all of them death from the condition.
• H5N1 pressure of Type A Influenza virus
Fifteen people have died a few of the 22 laboratory confirmed human cases. Median age a few of the human circumstances is 16.five years and part of the instances had been females. Since the start of the outbreak, nearly 3 million chickens have died/culled within the nation.
First time reported within the nation on 12th December 2003, and just about 1.1 million chickens and geese have died/culled. No human instances have been reported
The 1st case was a 7-year-old boy from Suphanburi province who advanced fever and cough on 3 Jan 2004 and improved to Acute Respiratory Distress Syndrome (ARDS) on 13 Jan 2004. The 2d case was once a 6-year-old boy from Kanchanaburi province who evolved fever on 6 Jan 2004 followed by way of severe pneumonia with ARDS a week later. Nearly 6 million chickens have died/culled on this country. To date a complete of 9 circumstances were reported with 7 of them demise from the illness. The median age of the human instances is 6 years and 20% of them are females.
More than 10,000 chickens have died/culled. First reported throughout the outbreak at the 12th of Jan 2004, there were no studies of any human case of avian influenza.
Nearly 50,000 chickens have died and not using a reviews of any human circumstances thus far
Thousands of hen have died (the exact quantity is yet to be disclosed ) on the other hand there were no human circumstances reported officially to date
Millions of chickens are reported to have died over the recent months and is now confirmed to be brought about through H5N1 pressure of the Type A influenza virus.
Reports of avian influenza amongst chicken populations (poultry chickens and geese) were reported (suspected or confirmed) from 14 of the nations 31 provinces and regions. The precise numbers of affected inhabitants are expanding and the outbreak is now showed to be reason through H5N1 strain. No human instances have been reported to date by means of the Chinese authorities.
Till now the reservoir appears to be wild and domestic chickens and turkeys, with people being reported to only have symptomatic cases.
Mode of transmission
Route and mode of spread in step with current evidences includes;
- Bird to chook
- Bird to individual contact
- There isn’t any scientific consensus on human to human unfold of the H5N1 strain.
Incubation Period and traits of H5N1 virus
Incubation length is understood to be of 1 week on an average. The virus is can be killed by way of warmth (56 zero C for six hours or 60 zero C for 30 mins). The virus is known to survive at cool temperatures, in infected manure of poultry birds for no less than three months. In water the virus is understood to survive upto four days at 22 degrees Celsius and greater than 30 days at zero degrees C.
Period of Communicability
There is no proof of transmission all through the incubation length or convalescence periods. Communicability increases with the severity of disease and stage of direct publicity. The virus is understood to continue to exist in chilly temperatures and in infected manure of birds for upto three months. In water it should live on upto 4 days at 22 levels C and greater than 30 days at zero levels C
Portal of entry
- Faeco-oral direction (among human or birds)
- Upper respiratory tract amongst people
Portal of exit
- Faeces, saliva and nasal secretions of infected birds
- Main upper breathing tract amongst humans
Source of infection
- Faeces among birds
- Respiratory discharge among humans
Susceptibility and resistance
- All age and sex groups are inclined. Most of the cases have passed off a number of the poultry bird handlers, which could be defined by way of length and degree to the source of infection.
- Growing concern has been raised in the medical community because the onset of outbreak is that there could also be a chance of reassortment of the H5N1 pressure with an current human influenza strain among such persons who get exposed to the H5N1 pressure whilst at the same time as affected by a publicity/episode of human influenza.
- In such instances a mixture (reassortment) of the two strains would possibly lead to a brand new/mutated version of the influenza virus for which recently no drugs and vaccine were developed and which may raise top transmission properties and might lead to higher case fatality charges than the H5N1 form.
- Initial analysis of viruses remoted from the lately deadly circumstances in Vietnam indicates that the viruses are invariably resistant to the anti-retroviral drugs like M2 inhibitors (rimantidine and amantadine). Studies to verify the effectiveness of neuraminidase inhibitors against the present H5N1 strains are currently underway.
Initially flu-like signs
- Rapid onset of high grade fever (> 38oC) adopted through muscle aches, headache, sore throat.
- In some circumstances there is also unilateral or bilateral pneumonia, progressing to acute respiratory distress requiring assisted respiring on respirator.
Case Fatality Rate (CFR)
- In the current outbreak, the case fatality price is starting from 70 – 75 % a few of the reported human instances of Vietnam and Thailand
- Diagnosis Hemagglutinin inhibition (HAI), ELISA, IFA with HF5 monoclonal antibodies and RT-PCR have been developed. Virus isolation is the key factor in identifying the sub-type of the influenza virus
Specimens for laboratory exams
- Throat and/or nasopharyngeal swab
- Nasopharyngeal aspirate
- Blood for whole examination and serology
- Blood for molecular biological research
Collection and transportation of medical specimens
- Procedure for specimen collection among humans
- Nasopharyngeal swab
- Insert a sterile swab underneath the inferior turbinate of either nostrils and depart in position for a few seconds.
- Slowly withdraw with a lively rotating motion in opposition to the mucosal surface of the nostril.
- Repeat the same process within the different nose using a new sterile swab.
- Collect the tip of each and every swab in a vial containing 2-3 ml of viral shipping media (VTM) with the applicator stick damaged off.
- Take a swab after energetic rubbing from the posterior pharynx.
- Collect the swab into vial with the applicator stick broken off containing VTM in it.
- Nasopharyngeal secretions are aspirated thru a catheter connected to a mucous trap and fitted to a vacuum source.
- The catheter is connected right into a nostril parallel to the palate, vacuum is applied and the catheter is slowly withdrawn with a rotation motion.
- Mucous from the opposite nostril is amassed with the same catheter in identical manner.
- After amassing mucous from each the nostrils, the catheter is flushed with 3 ml of VTM.
Collect 3-five ml of human blood soon after the onset of medical symptoms. Two samples wish to be taken from every affected person, one sample all through the first week of sickness and the second one 2-4 weeks later.
- Collect tissue and heart blood in deadly instances.
- Divide lungs tissue into two, position half portion in 10% formalin or formal-saline and the rest part as fresh.
Procedure for specimen assortment amongst poultry birds
In liaison with designated laboratories, full blood and post mortem specimens (intestinal contents, anal and oro-nasal swabs, trachea, lung, gut, spleen, kidney, mind, liver and middle) is also accrued for identity of virus via an identical diagnostic ways as for humans.
Draft case definition
Person with acute respiration sickness, characterised by fever (temperature >38 degrees C) and cough and/or sore throat and both contact with a confirmed case of influenza A (H5N1) during the infectious duration OR contemporary (lower than 1 week) seek advice from to a poultry farm in a space recognized to have outbreaks of Pathogenic avian influenza (HPAI) OR worked in a laboratory this is processing samples from individuals or animals that are suspected for highly HPAI virus infection.
Possible case AND limited laboratory evidence for Influenza A (H5N1) (corresponding to IFA + using HF5 monoclonal antibodies) OR no proof for another reason for illness.
Positive viral culture for avian influenza A (H5N1) virus OR positive PCR for influenza (H5) virus OR a four-fold rise in H5-specific Ab titer.
Exclusion standards • A case must be excluded if an alternate prognosis can fully provide an explanation for the sickness
Incidence and Geographical Distribution • The avian influenza started with studies in poultry birds in Vietnam since October 2003. Since then poultry birds were affected in South Korea, Thailand, Taiwan, Japan, Cambodia and Indonesia
From the available information and retrospective surveillance, it’s obvious that the human form of the disease can have started in Vietnam in October 2003, on the other hand on January 26, 2004 the Vietnam govt reported its first showed circumstances within the south of the rustic, with two instances in Ho Chi Minh City. Since then human instances have been reported from Thailand.
Seasonality Cases among fowl populations can occur year round. However instances and outbreaks in poultry rooster are recognized to occur extra frequently right through wintry weather months.
Human outbreaks had been reported since 1997 (five outbreaks in all prior to the prevailing one). Seasonal patterns might converge with the hen outbreak seasonality, which is understood to be extra commonplace in winters.
Alert threshold Even a single case should lead to an alert and adequate response.
Risk elements for increased transmission
- Population movement
- Travel to/from the international locations from the place cases of avian influenza have been reported.
- Access to health products and services
- Prompt identification of the instances is paramount to hastily put into effect the keep watch over measures and for a success treatment.
Prevention and Control measures
Care and Management of the Cases
Among Poultry birds
World Health Organization recommends culling of birds (burn or burial) with spraying of disinfectants at the site of the burial; as a measure to stick ahead of the combat to stop the spill over of this type of influenza into human populations.
Among Human Population
- Good supportive care together with in depth treatment has been shown to toughen the prognosis.
- 2003-04 trivalent influenza vaccine (flu shots) OR intranasally administered are living, attenuated influenza vaccine (LAIV, a nasal-spray flu vaccine) for chemoprophylaxis is available.
- Two classes of substances are to be had. These are the M2 inhibitors (amantadine and rimantadine) and the neuraminidase inhibitors (oseltamivir and zanimivir). These medicine were approved for the prevention and remedy of human influenza in some nations, and are considered efficient without reference to the causative pressure.
Management of suspected human case
- Patients with suspected avian influenza symptoms must be remoted and cared for the use of barrier-nursing tactics by means of providing surgical mask to the patient.
- Detailed clinical, touch and trip historical past together with incidence of acute breathing illnesses in contact individuals all over the final 10 days.
- X-ray chest (CXR) and complete blood count:
If CXR is normal,
– discharge the affected person with advice to seek hospital therapy if breathing
– reinforce non-public hygiene and
– avoid public areas and transportation, confine at home until smartly.
• If CXR demonstrates unilateral or bilateral infiltrates with or without interstitial infiltrations, see management of possible case.
Management of probable case
Hospitalize under isolation or cohorted with different avian influenza sufferers
• Lab investigation to exclude identified cause of abnormal pneumonia:
– Complete blood image
– Serology from blood samples
– Throat and/or nasopharyngeal swabs and cold agglutinin
– Bronchoalveolar lavage
• Specimens will have to be collected on exchange day and investigated within the
laboratories with right kind containment facilities (BL3)
• CXR as clinically indicated
• Treat as clinically indicated (symptomatic remedy)
– Broad spectrum antibiotics have now not confirmed effective in halting hen flu progression thus far. Effectiveness of remedy through M2 inhibitors and neuroaminadase inhibitors is below investigation.
Management of touch of suspected and probable cases
- Record identify and phone in detail.
- Advice to hunt scientific help within the tournament of fever or respiration symptoms aggravate.
- Immediately report back to the health authority.
- Do now not report to work till prompt by way of the physician.
- Minimize contact with members of the family and friends and steer clear of public places.
Hospital Infection Control Guidance
- Strict adherence with barrier nursing of avian influenza affected person
- Use precautions for airborne, droplet and speak to transmissions
- Rapidly divert the patient reporting to well being care facility with flu-like symptoms to a separate space to reduce transmission to others.
- Suspect case should put on surgical mask till avian influenza is excluded
- Isolate the patient and accommodate as follows
- Negative pressure rooms with door closed
- Single room with their own bathroom facilities
- Cohort placement in a space with an independent air provide and exhaust device
- Turn off air condition in a facility and open home windows for good air flow
- Patient beneath investigation for avian influenza must be separated from those diagnosed with the syndrome
- Disposable equipments must be used. If gadgets are to be reused, they must be sterilized with broad-spectrum disinfectants (bactericidal, fungicidal or veridical) of proven efficacy.
- Restrict motion of patient up to possible. If essential, affected person should wear surgical masks to reduce dispersal of droplets.
- Visitors, workforce, scholars and volunteers should put on N95 masks on entering the room of the affected person
- Hand washing earlier than and after contact with any patient is crucial hygienic measure in combating the spread of infection.
- Health Care Workers (HCWs) will have to wear gloves for all patients handling and gloves must be changed after any contact with the pieces likely to be contaminated with breathing secretions.
- HCWs should wear protecting eyewear or face shields or mask during procedures the place there’s doable splashing, splattering or spraying of blood or different body substances of the patients suspected, possible or showed avian influenza.
- Standard precautions will have to be carried out when dealing with any clinical wastes. Gloves and protecting clothes must be worn whilst dealing with scientific waste baggage and packing containers. Manual handling will have to be have shyed away from and scientific waste should be positioned in leak-resistant biohazard bags or packing containers categorized and disposed of safely.
Safety measures for Poultry bird employees, cullers and poultry transporters
Ensure that the cullers use the next protective items:
- N95 respirator mask are preferred. Standard well-fitted surgical masks should be used if N95 respirators don’t seem to be to be had
- Protective clothes, ideally coveralls plus an impermeable apron or surgical gowns with long cuffed sleeves that may be either disinfected or discarded.
- Heavy responsibility rubber work gloves that can be disinfected
- Goggles/protecting glasses
- Rubber or polyurethane boots that may be disinfected or protecting foot covers that may be discarded
- Persons at prime possibility for serious headaches of influenza (e.g. the immuno-compromised, the over 60 years old, or other people with identified continual middle or lung illness) will have to keep away from working with affected chickens.
- All individuals who have been in close contact with the infected poultry should wash their hands incessantly with soap and water. Cullers and transporters should disinfect their arms after the operation.