The past and present scenario of avian influenza and its control strategy in Bangladesh: A review

Abstract

Avian influenza virus (AIV) is a pandemic thread and this year 2018 is passing the century of Spanish flu (H1N1) of 1918 when the world approximately 50 million human deaths occurred worldwide. About 1.7 million peoples become died in over Asia from 1957 to till now by the name of Asian flu (H2N2) at 1957 and Hong Kong flu (H3N2) at 1968. In Bangladesh, since first identification of Highly Pathogenic Avian Influenza (HPAI) at 2007 poultry industry faces outbreaks at a significant level in every year although human infection is uncommon. The infections spreading among all major avian species like chicken, duck, turkey, quail. On the other hand it is reported that the infection is spreading among wild birds like house crow, migratory birds and wild animals also. During first isolation the virus were in clade 2.2.2 but after several mutations over 11 years now it becomes under clade 2.3.2.1a and circulating in environment. Government of Bangladesh decided to vaccinate against AIV in 2012 with two killed and one vector vaccine to combat the AIV that brings a satisfactory result. But from the couples of years again the incidence of AIV becomes very high and ongoing researches like sink surveillance shows 50-90% live bird markets of Dhaka and Chattagram districts are infected. To combat the AIV it is recommended that farms should have to ensure the good quality vaccine with good farm biosecurity practice along with conventional stamping out program.
 Bangladesh J. of Livestock Res. 21-25: 24-28, 2018

Combined usage of rHVT-H5 and Re-6 vaccines towards an effective avian influenza vaccination program for commercial layer chickens

“…In 2013, a recombinant live vaccine rHVT-H5 (Vectorimmune AI, Cevac) has been first licensed in the USA and other Avian Influenza virus (AIV) endemic countries like Bangladesh, Egypt and Mexico for AIV H5N1 (6,18). At the same time, Bangladesh has been accredited one more killed vaccine Re-6 (Merial).…”

“…In contrast, Re-6 is an inactivated vaccine that carry the HA and NA genes from clade 2.3.2.1 H5N1 virus (A/duck/Guangdong/S1322/10 (DK/GD/S1322/10) is widely used in chickens in China, Korea, and Southeast Asian countries including Bangladesh since 2012 (6,15). There are two clades of AIV H5N1 which have been circulating in Bangladesh since 2012 including clade 2.3.2.1 and clade 2.3.2.1a (7)(8).…”

“…The HPAI H5N1 was first recognized in Bangladesh in February 2007 and faced a massive economic loss of US$ 454.5 million in 2007 to 2008 (3)(4). Since then, 556 cases have been reported from Bangladesh and have become prevalent every year mainly during winter season (5)(6). These annual outbreaks have been estimated to cause noteworthy monetary losses in the poultry in the country as a result of high mortalities of birds, cost of medication and decreased poultry yields.…”

“…These annual outbreaks have been estimated to cause noteworthy monetary losses in the poultry in the country as a result of high mortalities of birds, cost of medication and decreased poultry yields. In a bid to combat influenza outbreaks in poultry, two vaccines against HPAIV H5N1 namely rHVT-H5 (Vectormune AI, Cevac) a live vaccine and Re-6 (Merial) an inactivated vaccine were officially licensed in Bangladesh in 2013 (6)(7)(8). The rHVT-H5 is a recombinant vaccine constructed by inserting Haemagglutinin (HA) gene of clade 2.2 HPAIV H5N1 (A/swan/Hungary/4999/2006) together with a cytomegalovirus promoter into a non-essential growth region of FC126 strain of Herpesvirus of turkey (HVT) (9)(10).…”

Potential risk factors of avian influenza virus infection in asymptomatic commercial chicken flocks in selected areas of Bangladesh during 2019

“…The HPAIV (H5N1 and H7N9) is characterized by severe illness and 100% death in infected birds [ 6 ]. HPAI H5N1 was first identified in Bangladesh in February 2007, and still several waves of the outbreak occur every year with high mortality in the poultry sector [ 7 , 8 ]. The prevalence of HPAI H5N1 has a seasonal pattern in Bangladesh, and outbreak waves start registering in late autumn, peaking in spring, and then decrease frequency gradually during the summer season [ 9 ].…”