Outbreak Investigation of Officially Reported and Highly Pathogenic Avian Influenza (H5N8 Subtype) in Iran During 2016

On 14 November 2016, an outbreak of highly pathogenic avian influenza (HPA) was reported from a commercial layer farm located in Malard, Tehran Province, Iran. This study aimed to investigate the HPAI H5N8 outbreaks in Iran. The questionnaire was prepared and completed through interviews with farm owners or field observations at the time of disease onset from November 2016 to February 2017. The HPAI H5N8 infection was confirmed in 30 different locations including 10 villages (33.3%), nine-layer farms (33%), two broiler breeder farms (6.67%), one layer breeder farm (3.3%), one turkey farm (3.3%), one partridge farm (3.3%), five national parks (16.7%), and one wetland (3.3%) in 12 provinces of Iran. The cumulative incidence rates of disease in villages, layer farms, broiler breeder farms, layer breeder farms, partridge farms, and turkey farms were 0.02%, 0.87%, 0.55%, 6.25%, 7.14%, and 0.69%, respectively. The findings reflect that among the investigated variables at infected locations, new birds entering the home in villages, live bird markets, inappropriate biosecurity conditions, transporting manure during the breeding period, close proximity of a common road to infected farms, and poultry movement inside (pullet) and outside were the most frequently observed possible risk factors for these outbreaks. In conclusion, attention should be focused on the study of the dynamics and movements of domestic poultry, investigation and modification of the structure of industrial poultry farms, training for all related people, enhancement of passive surveillance, an increase in biosecurity, raising the awareness of the authorities on the importance of the infection, and provision of the required credits and facilities.

Effectiveness of Thermostable Vaccine for Newcastle Disease Produced by the Razi Institute on Backyard Poultry in Iran during 2015

Newcastle disease causes many economic losses to the poultry industry in most countries. This disease is endemic in Iran. Backyard poultry is considered the reservoir of Newcastle virus; however, there is either no vaccination program against Newcastle, or it is performed in a restricted manner. Commercial live vaccines are inactive and sensitive to temperature; moreover, vaccine delivery to villages and remote areas requires special equipment and high cost to maintain the cold chain. This study evaluated the effectiveness of a thermostable Newcastle vaccine produced by the Razi Institute (ND.TR.IR) on the backyard poultry. In four provinces, at least 4 villages were selected as the treatment group, and the same number was selected as the control group. At least, 30 birds were sampled in each village. In each group, blood samples were collected before vaccination and 2 weeks later, and the serum titer of the samples was examined with the haemagglutination inhibition test. The arithmetic mean and standard deviation of the sample titers at the rural level were compared using paired t-test before and after vaccination in each group. Moreover, Repeated Measures ANOVA was utilized to compare the vaccinated and control groups in terms of the titer changes before and after vaccination. In this study, 584 and 389 samples were taken from the treatment (53 households in 20 villages) and control groups (33 households in 14 villages). The mean serum titer values of Newcastle were 4.51±3.03 and 6.64±2.48 in the treatment group before and after vaccination, respectively (P<0.001). The increase in mean titer of the treatment group (2.31 log) was statistically higher than that in the control group (0.66 log) (P<0.001). Out of 584 birds, 517 (88.5%) ones had titer above 3 in the second turn in the treatment group. The thermostable vaccine (ND.TR.IR) produced by the Razi institute is suitable for backyard poultry, which immunizes them against Newcastle disease. Appropriate vaccination programs for backyard poultry should be made; moreover, vaccination of backyard poultry can be effective in preventing the circulation of the field viruses.

Prevalence of Avian Influenza in Live Bird Markets, Bird Gardens, and Zoos in Iran in 2015: A Cross-sectional Study

Avian Influenza (AI) H9N2 is endemic in Iran; therefore, it is necessary to estimate the disease prevalence among birds in live bird markets (LBMs) and assess the risk spread across the country. Accordingly, this study aimed to estimate the prevalence of AI subtypes in LBMs, bird gardens, and zoos during October and November 2015 in Iran and investigate the associated risk factors. Data related to independent variables for birds and premises were collected using a prepared questionnaire which included items about previously known potential risk factors associated with avian influenza infection. Serological testing was carried out to detect the antibodies against H5, H7, and H9. Regarding H5 and H7, the antigens H5N2 and H7N1 were used in this study. Positive samples on the first test were examined with the second antigens, namely H5N1 and H7N7. Moreover, sera with titers ≥4 (i.e. log2) were considered positive and premises with at least one positive bird were considered as positive units. In total, 87 premises were included in this cross-sectional study. Serum samples were examined utilizing hemagglutination inhibition, and RT-PCR was conducted on swab samples. Regarding the molecular test, the RNA was extracted using the High Pure Viral RNA Kit (Roche, Germany). In addition, real-time RT-PCR was conducted based on the described method. The seroprevalence rates of H9N2 were 83.9% and 31.8% at the premises and bird levels, respectively. Totally, 9.2% of pooled swab samples were positive for H9N2. However, all sera and swab samples were negative for H5 and H7. Hot and humid weather (OR=0.13, 95% CI 0.02 – 0.78) as well as bird-keeping condition (i.e., enclosed area) (OR=0.11, 95% CI 0.012 – 1.02) were protective factors for H9N2. High seroprevalence rate of H9 indicates that the disease is endemic in Iranian LBMs. Active surveillance must be carried out in LBMs, especially in the northern provinces of Iran. In addition, cleanliness and improved hygiene would be useful to prevent the spread of disease in LBMs.