Monday, October 14, 2019
Highly Pathogenic Avian Influenza (HPAI) Prevention
Highly Pathogenic Avian Influenza (HPAI) Prevention Administrative structure Bangladesh has 7 divisions, 64 districts and 489 upazilas or sub-districts [Bangladesh National Portal. Source: http://bangladesh.gov.bd] and share borders with India (about 4,246 km) and Myanmar (193 km). Each upazila or sub-district consisting of multiple unions, each unions consisting of nine villages (in rural areas)/ wards (in metropolitan areas) and each ward consisting of multiple mauzas (in rural areas)/ mahallas (in metropolitan areas). In metropolitan or sub urban area, unions are replaced with pourashava i.e municipality and city corporation. There are 4550 unions [Bangladesh National Portal. Source: http://bangladesh.gov.bd/site/view/union-list], 56348 mouzas, 11 city corporations and 317 municipalities in Bangladesh [Bangladesh bureau of statistics (BBS). 2014. Statistical pocketbook of Bangladesh-2013: www.bbs.gov.bd]. Source: Cabinet Division- Government of the PeopleÃ¢â¬â¢s Republic of Bangladesh: http://www.cabinet.gov.bd/site/page/fe6c7332-5568-4dd7-bd37-d08120931ccd Control scenario Following are the scenario to control the HPAI in Bangladesh- Stumping out- Bangladesh government approved traditional Ã¢â¬Å"stamping outÃ¢â¬ control strategy to fight against HPAI since its first detection in 2007. A basic Ã¢â¬Å"stamping outÃ¢â¬ consist of (a) infection detection (b) affected bird quarantine and (c) culling of affected and in-contact poultry (d) decontamination and (e) surveillance after outbreak. At beginning, the government implemented stamping out in the affected farm and all farms located in 5 KM radius of affected farm. Then government revised this decision due to poultry industry protest and enacted new Ã¢â¬Å"stamping outÃ¢â¬ rule: stamping out in affected farm and all farms located in 1 KM radius of affected farm. Currently stamping out was only limited to the affected poultry farms (1, 2). Early detection and early response were stressed to control the HPAI in Bangladesh, but late reporting and late response usually hampered the early detection and early response process in Bangladesh. To facilitate the early detection, a HPAI active surveillance program through SMS based reporting system was introduced in Bangladesh which was closed because of fund crisis. In addition, avian influenza compensation strategy was adapted for the owner of the culled poultry farmer in June 2008 which was also closed due to fund availability. Under those circumstances the number of informing gradually reduced (1). Restriction in the movement of poultry Limit in the poultry movement was also enforced but this process was not successful to limit the entry of sick poultry into the live bird market (1). Vaccination (trial basis) in parent stock and commercial layer farm Islam (2015) stated that though Bangladesh introduced vaccination at certain areas in 2013 and 2015, the effect of vaccination is still need to be assessed (1). According to vaccination policy, vaccination on poultry flock is depend on farmer determination, however permission from livestock authority is necessary as livestock authority is responsible for post-vaccination investigation. In addition, poultry farmer is responsible to pay the immunisation and vaccine expenses. In the trial site, vaccination was carried on parent stock (100%) and commercial layer flock (50%), however vaccination was not done in broiler flock. According to number of farm in the trial site, a lower percentage of commercial layer poultry farms were came under vaccination in Gazipur (33%) and Bajitpur (55%). Trial documented uneven antibody response in between the farm and within the poultry farm. In addition, an unprotective antibody level (2 5 (or32)) has been documented in few poultry bird. On the other ha nd, many poultry birds documented protective antibody level (from Log2 5 to Log2 6). Antibody level ranged Log2 5 to Log2 6 is assumed to provide protection against clinical HPAI while this level is unable to reduce the shedding of HPAI. The trial also documented diverse antibody response with different type of vaccine. Post-vaccination outbreaks has been documented in many countries mainly due to scarce vaccination coverage in the main host species (1). Outreach and health education: 10 recommendation messages (Table 1) has been published by Bangladesh government to prevent HPAI H5N1 in human and disseminate those through TV, radio, print media and Department of Livestock Service led public meeting. Government adopted those recommendation from a UNICEF-WHO-FAO-Japan Government joint publication (3). Shanta et al. (2012) documented the percentage of backyard poultry raiser who trailed Bangladesh Government 10 messages after four yours of first detection of HPAI H5N1 in Bangladesh and stated that government should revised 10 messages to lower the risk of HPAI H5N1 in human population (Figure 1). In addition the author stressed on communication pathway and appropriateness of proposed human behaviour in HPAI H5N1 control program (3, 4). Sultana et al. (2012) has the similar findings and also stated that backyard poultry farmers unable to follow the government message because bringing change in low earned backyard poultry farmer existing behaviour require more time an d more financial capacity (5). Table 1: Bangladesh Government 10 recommendation or message to prevent HPAI H5N1 transmission in human (3) Figure 1: Percentage of backyard poultry raiser who trailed Bangladesh Government 10 messages to prevent HPAI H5N1 transmission in Human (2009-2011) (3, 4) Bangladesh adopted different control measure from basic stamping out technique to vaccination (mentioned in above section) since first detection of HPAI H5N1 in poultry in 2007. There is a very limited alternative control method left except strengthening the current control measure to control the HPAI in Bangladesh. After reviewing the control methods in my opinion stamping out a combination of stamping out (only on the affected farm) and vaccination on 1 km radius around the affected farm can be a best practice to control HPAI in Bangladesh. For example, one study proposed a combination of stamping out (1 km radius around the affected farm) and vaccination (3 km radius around the affected farm) to control AI in Belgium (6). Second best control option, stamping out only in the affected farm, which is currently practicing in Bangladesh, is the best method for controlling AI in Bangladesh as the number of bird culling is limited when we compare it with stamping out in 1 km radius and 5 km radius around the affected farm. Third best control option, vaccination in layer, broiler and backyard poultry is an alternative control method for Bangladesh. However, regular monitoring on post-vaccination flock with veterinary authority is necessary to prevent the outbreak of avian influenza with vaccine strai n. For example, one study identified AI in a vaccinated poultry without presentation ill signs even though many birds demonstrate high antibody level (Log 27 to Log 28) (7). The worst control method, Ã¢â¬Å"stamping outÃ¢â¬ in 1 km radius and 5 km radius around the affected farm as Bangladesh has high poultry density (1460 poultry/km2) (8) and culling of large number of birds lead to financial loss of poultry farmer. The following are the items that will need to estimate the prevention and control costs per method 1.Islam MR. Global and local challenges in the control of avian influenza. 9th International Poultry Show Seminar; Dhaka, Bangladesh: World Poultry Science Association-Bangladesh Branch; 2015. p. 5-14. 2.Haider M, Applebaum B. Disease Management of Avian Influenza H5N1 in Bangladesh-A Focus on Maintaining Healthy Live Birds: INTECH Open Access Publisher; 2011. 3.icddrb. Backyard poultry raising practices in Bangladesh: implications for risk of avian inflenza infection in humans. Health and Science Bulletin 2012;10:1-8. 4.Shanta IS, Hasnat MA, Mikolon A, Khan MSU, Haider N, Bhuyan AA, et al. Backyard Poultry Rearing Practices in Bangladesh: Implications for Risk of Avian Inflenza. 2012 International Conference on Emerging Infectious Diseases; March 11-14, 2012; Atlanta, Georgia Centers for Disease Control and Prevention; 2012. 5.Sultana R, Rimi NA, Azad S, Islam MS, Khan MSU, Gurley ES, et al. Bangladeshi backyard poultry raisersÃ¢â¬â¢ perceptions and practices related to zoonotic transmission of avian influenza. The Journal of Infection in Developing Countries. 2011 2011;6(02):156-65. 6.Vandendriessche Y, Gellynck X, Saatkamp H, Dewulf J, Van Steenwinkel S, Vermeire B, et al. Economic evaluation of strategies to control high pathogenic avian influenza in Belgium. Lucrari stiintifice Seria Zootehnie-Universitatea de Stiinte Agricole si Medicina Veterinara Ion Ionescu de la Brad (Romania). 2010. 7.Giasuddin M, Rahman MH, Hasan M, Karim MR. Isolation of Avian Influenza Viruses from Vaccinated Chicken Flocks of Bangladesh. In: Husain M, editor. 8th One Health Bangladesh Conference; Dhaka, Banfgladesh: Scientific Sub-Committee, 8th One Health Bangladesh Conference; 2015. p. 7. 8.Biswas PK, Christensen JP, Ahmed SSU, Barua H, Das A, Rahman MH, et al. Avian influenza outbreaks in chickens, Bangladesh. Emerging infectious diseases. 2008 2008;14(12).