No need for scare Opinion & Comment / Technical Articles Posted by agrilive on Mar 07, 2004 - 02:05 PM Dr. Khushi Muhammad, Dr. Muhammad Akram Muneer, Dr. Masood Rabbani & Dr. Muhammad Aleem (Faculty of Veterinary Science, University of Veterinary and Animal Sciences, Lahore) Reference to the issue of recently reported avian influenza (AI) outbreaks in poultry at Karachi, it is submitted that AI is common in poultry in many countries. The outbreak of AI was first time recorded in October 1994, in broiler breeders in Northern Areas of Pakistan (Mansehra, Abbotabad, Rawalpindi, Murree, etc), killing approximately one million birds. However, other regions of the country remained free from AI disease due to in time implementation of various disease control strategies through the joint and collaborative measures of various public and private organizations dealing with poultry. The Government livestock research and development institutions, extension workers, and the UVAS teachers coordinated / collaborated with each other and the morbid tissue samples collected from the sick birds were processed in the private and public disease diagnostic laboratories for the isolation and identification of the pathogens causing outbreak of suspected AI disease. The causative agent of 1994 outbreak was confirmed as Avian Influenza virus (H7 N3 type) and this isolated virus was purified and processed for preparation of inactivated vaccine that was used on mass scale to control the disease outbreak in poultry. In 1996, outbreaks of the avian influenza in broilers, breeders and commercial layers were recorded in various areas of the Punjab. Although, this syndrome did not induce considerable mortality in the infected birds it did mitigate egg production performance of laying birds (commercial layers and breeders). The infection with this AI virus also induced impairment of the normal functioning of immune system in infected birds, rendering the birds more susceptible to other infectious diseases. Some of the diagnostic laboratories reported the isolation of various bacterial pathogens from the infected broilers, and the birds on some of the commercial farms recovered following treatment with broad-spectrum antibiotics. So this created controversy amongst the farmers and poultry diagnosticians / experts. In the UVAS research laboratories, the causative agent from the diseased birds was isolated and characterized as Avian influenza virus H9N2 type. Keeping in view the virulence and the economic impact of isolate for the poultry, this virus was also included in the locally prepared Avian Influenza vaccine. The AI vaccine containing locally isolated H7 and H9 types has thus been quite extensively used in poultry since 1996. However, this combined H7 and H9 vaccine was not routinely and properly used at poultry farms in Karachi area. This ignorance of proper vaccination of flocks lead to appearance of Avian influenza cases in broiler flocks which were being reared in Karachi area during 1999. As the non-usage of vaccines against AIV lead to perpetuation of the virus on the farms, and the AIV (H9 N2) became endemic in flocks in Karachi region. In October 2003, the AI virus hit the commercial layers and induced heavy mortality. In addition to influenza various other pathogens also contributed to such casualties at the layer farms. The disease was mainly recorded in non-vaccinated birds. The Pakistan Poultry Association (PPA) in January 2004 organized a meeting of the National Disease Control Committee at Karachi and discussed various approaches regarding investigation and control of the problem. The samples obtained from dead and moribund birds were processed in various diagnostic laboratories. In the UVAS Diagnostic Laboratory Avian Influenza virus H7 type was isolated from the morbid tissue samples. Presently, the poultry farmers at Karachi are still reluctant to vaccinate their birds against Avian Influenza as they report that despite vaccination, the AI occurrence is still not controlled. It is reported that various physical, chemical and biological immunosuppressive factors, prevail on those farms and hinder the immunocompetency of birds and immunogenicity of vaccines and not allowing the birds to achieve the desired level of the immunity against various pathogens including AI viruses. Avian influenza viruses isolated so far from poultry in Pakistan have been typed as H7N3 and H9N2 on the basis of 2 virus surface antigens: the haemagglutinin (H) and neuraminidase (N). So far, H antigen has 1-15 types and the N antigen has 1-9 types. In any outbreak of influenza, the causative influenza virus will have either number of H and N antigens such as H9N2, H7N3 and H5N1 etc. In fact AI virus is highly mutagenic in nature, and could emerge into over hundred types, which may be pathogenic for humans, chickens or other animals. It is worth mentioning that Avian Influenza viruses so far isolated from Pakistan have confined to the chickens and their communication to human or other animal species has not been reported. The AI viruses could mutate in the infected host species into the serotype that may be pathogenic and communicable to humans or other animal species. However, this is a rarely occurring phenomenon. An example is AIV H5N1 type, which is pathogenic both for chicken and humans. It is very important to note that in Pakistan there are over 20,000 poultry farms of different capacities and over 500,000 laborers work on those farms and are always in direct contact with the poultry birds of various age groups. No contact of AI virus by the humans at those farms from the poultry has been reported since 1994 till to date by any of the medical authority in any area of Pakistan. There is ability of influenza viruses that have evolved and continue to circulate in avian or porcine reservoirs to emerge, either through genetic reassortment or through direct transmission and spread in the human beings at irregular intervals. Influenza epidemics affected human population as early as the 16th century. In 18th and 19th centuries outbreaks of respiratory disease among horses were recorded concurrently with outbreaks in humans. However, direct evidence for horse-to-human transmission of influenza viruses is lacking. In recent past, pigs have been accorded a prominent role in the generation of major influenza outbreaks. Classic influenza A (H1N1 swine viruses, Avian A (H1N1) and human A H1N1, H3N2 all have been isolated from naturally infected swine (Reservoir of influenza A viruses exists in pigs worldwide). In Pakistan, lot of technical manpower is being produced every year in Veterinary Teaching Institutions like University of Veterinary and Animal Sciences, Lahore. During their Master and Doctorate programs, the students are trained in various techniques on isolation and characterization of pathogenic bacteria, viruses and fungi infecting the indigenous livestock and poultry. Currently many well-equipped diagnostic laboratories employing trained graduates are present in various parts of the country. These laboratories of public and private sectors are engaged in isolation and identification of pathogens of livestock / poultry and production of vaccines against those isolates. The technical staff of those laboratories also guides the poultry farmers on diagnosis, symptomtology, treatment and prevention and control of infectious diseases. The UVAS diagnostic laboratory like others is fully competent in both staff and equipment/ resource wise to deal with and advise on outbreaks like AI in birds in Karachi. However, the danger of contracting AI virus by humans should be taken very seriously and various measures for verifying cross poultry-humans AI virus infections need to be further strengthened at the Departmental laboratories run by the health and veterinary departments. Special emphasis would be required on isolation and quarantine facilities for human beings suspected of getting AI virus. we are sure the medical institutions do have facilities for isolation, characterization and typing of viruses being reported in Pakistan. This arrangement is needed to rule out the possibility of outbreaks of the influenza in human beings and based on such data, health department can immediately counteract with confidence to base less statements which off and on appear in our national press, and create uneasiness in human minds about their health status. SUGGESTED CONTROL MEASURES For complete surveillance, control and eradication of the avian influenza problem all segments of the society are suggested to implement the following measures in their respective domains: For Poultry Farmers: 1. All farmers are advised to strictly implement a planned and effective vaccination program against various pathogenic entities (bacteria and viruses). Proper and timely vaccination of chickens is the only available good method of keeping the infectious diseases under control. 2. It is further advised that for the flu virus control, the farmers must use inactivated Avian influenza virus vaccine according to the following schedule: Commercial Layers and Breeders S.No. Age of birds (weeks) Type of vaccine Dose and route 1 1-2 Alum adsorbed or precipitated AIV-vaccine 0.3ml/birdsubcut injection 2 6-8 Oil based AIV-vaccine 0.5 ml/birdSubcut injection 3 14-16 Oil based AIV-vaccine 0.5 ml/birdSubcut injection It is further added that birds may be revaccinated during production if the antibody titer falls below the required level. Commercial Broilers-vaccination schedule -1S.No. Age of birds (weeks) Type of vaccine Dose and route 1 1 Alum adsorbed or precipitated AIV-vaccine 0.3ml/birdsubcut injection 2 3 Alum adsorbed or precipitated AIV-vaccine 0.3ml/birdsubcut injection Commercial Broilers-vaccination schedule -2S.No. Age of birds (weeks) Type of vaccine Dose and route 1 1 Oil based AIV- vaccine 0.5ml/birdsubcut injection 3. The farmers experiencing the disease outbreaks at their farms must be very careful in visiting other farms or inviting persons from other to their farm or meeting persons from any other area. They should be good neighbours. It is better if they communicate through telephone. 4. Field veterinarians / farmers / vaccinators / poultry workers / feed suppliers must not visit more than one farm at a time without taking adequate disease prevention measures i.e. taking bath, changing of clothes and wearing of proper dress before entering to a farm 5. The farmers must keep their farm clean by using various cleaning, washing and disinfection materials in the event of an outbreak. They must not sell their birds, eggs and litter without proper treatment with disinfectants as the heavy contamination of these materials could spread the disease virus to the regions and areas currently free of disease. Avian Influenza viruses are highly sensitive to dryness, temperature (60 oC for 30 min), extreme pH (below 5), UV light (252 nm), and chemicals like formalin, iodine, chlorine (sodium hypochlorite solution, aldehydes (formaldehyde, aldekol-02), fat solvents (acetone, ether, spirit, etc), Virkon-S, etc. Treatment of litter to some of these disinfectants will help in prevention of infection from diseased to susceptible flocks. 6. Feed trucks must not deliver feed to many farms at a time. It is further advised that all the vehicles should be properly washed and disinfected prior to their entry and departure from the farms. 7. Completely destroy the vaccine vials specially when the farmers use live virus vaccines for inoculation of the flocks. 8. Disposal of dead birds needs special attention. Dead birds must not be offered to dogs, cats and other stray and wildlife neither the dead carcasses be thrown on roads / canals instead these carcasses should be deep buried or incinerated to keep contamination of farm premises under control. For this purpose, proper incineration and burial facilities be developed at every farm keeping in view the capacity of farm. 9. All the vehicles / personnel entering and leaving poultry farms must pass through a dip containing solutions of disinfectants. They must wear well-laundered uniforms before entering the poultry sheds. 10. The farm workers / supervisors must be conscious of their own health and they must practice hygienic and sanitary measures while working / visiting poultry flocks. For Veterinarians / Governmental Institutions: 1. Personnel involved in disease diagnosis must submit morbid samples from suspected and dead birds to diagnostic labs for isolation and characterization of causative agents of the disease. 2. These agents may be processed for serotyping and pathotyping. 3. The information inferred from the aforementioned investigation may be reported to the Government agencies and representatives of Pakistan Poultry Association (PPA) for their evaluation and proceeding for actions like convening meetings of experts and the Disease Control Committee (DCC) for reviewing the overall situation and for suggesting an action plan. 4. Director Generals of Provincial Livestock Departments / Federal government (Animal Husbandry Commissioner), with cooperation of PPA, PVMA, etc., may plan for (a) continuous sero-monitoring of the flocks (b) for production of biologics if required (c) issuance of instructions to farmers. For Consumers: 1. Most of the poultry disease pathogens are destroyed by the conventional cooking methods used in the houses. However, some of the western cooking methods such as half boiling and half cooking of food items may support the transfer of some of the pathogen. 2. Consumers of poultry meat / eggs and their bye-products are required to contact the personnel working in (a) Poultry Wings of the Livestock Departments (b) Consumer Education Wings of PPA (c) Poultry experts in Faculties of Veterinary Science in various Universities (d) Health Departments, for updating the information regarding any confusion about consumption of poultry products in the event of occurrence of any disease problem like Avian Influenza. DR KHALID MAHMOOD SHOUQ (D.V.M) http://www.masterytv.biz/agrilive http://www.mybiznas.com/agrilive EDITOR IN CHIEF THE VETERINARY NEWS & VIEWS [WEEKLY] 392-A, SAMANABAD FAISALABAD, PAKISTAN TEL.0092 41 665392FAX, 0092 41 665392 MOBILE, 0300 6620616-0303 6711581-82 E-MAIL: newsviews@bremail.com HTTP.pakissan.com http://www.freegb.net/readbook.cgi?24311 This article is from World Veterinary Association   http://worldvet.org/ The URL for this story is:   http://worldvet.org/modules.php?op=modload&name=News&file=article&sid=1648