Serological Evidence of Infectious Laryngotracheitis Infection and Associated Risk Factors in Chickens in Northwestern Ethiopia

Abstract

Infectious laryngotracheitis (ILT) is a disease of high economic consequence to the poultry sector. Gallid herpesvirus 1 (GaHV-1), a.k.a infectious laryngotracheitis virus (ILTV), under the genus Iltovirus, and the family Herpesviridae, is the agent responsible for the disease. Despite the clinical signs on the field suggestive of ILT, it has long been considered nonexistent and a disease of no concern in Ethiopia. A cross-sectional study was conducted from November 2020 to June 2021 in three selected zones of the Amhara region (Central Gondar, South Gondar, and West Gojjam zones), Ethiopia, with the objective of estimating the seroprevalence of ILTV in chickens and identifying and quantifying associated risk factors. A total of 768 serum samples were collected using multistage cluster sampling and assayed for anti-ILTV antibodies using indirect ELISA. A questionnaire survey was used to identify the potential risk factors. Of the 768 samples, 454 (59.1%, 95% CI: 0.56–0.63) tested positive for anti-ILTV antibodies. Mixed-effect logistic regression analysis of potential risk factors showed that local breeds of chicken were less likely to be seropositive than exotic breeds (OR: 0.38, 95% CI: 0.24–0.61). In addition, factors such as using local feed source (OR: 6.53, 95% CI: 1.77–24.04), rearing chickens extensively (OR: 1.97, 95% CI: 0.78–5.02), mixing of different batches of chicken (OR: 14.51, 95% CI: 3.35–62.77), careless disposal of litter (OR: 1.62, 95% CI: 0.49–4.37), lack of house disinfection (OR: 11.05, 95% CI: 4.09–47.95), lack of farm protective footwear and clothing (OR: 20.85, 95% CI: 5.40–80.45), and careless disposal of dead chicken bodies had all been associated with increased seropositivity to ILTV. Therefore, implementation of biosecurity measures is highly recommended to control and prevent the spread of ILTV. Furthermore, molecular confirmation and characterization of the virus from ILT suggestive cases should be considered to justify the use of ILT vaccines.

Seroprevalence and Associated Risk Factors of Infectious Laryngotrachitis in Small Scale Chicken Production in Nekemte Town and Selectted Districts of East Wollega Zone, Oromia, Ethiopia

“…The present finding agrees with the finding of Mohamad Inkyas et al, (2014) who reported 17.33% from Chitta gong districts of Bangladish and Tesfaye et al, (2019) with finding of 19.4% from central and southern parts of Ethiopia. On the other hand, the current finding was lower than the reports of Owoade et al, (2006), Roba et al, (2020; Salhi et al, (2021); Johnson et al, (2004); Madsen et al, (2013); Derksen et al, (2018), Birhan et al, (2022); who reported a seroprevalence of 20%; 59.1%; 54.7%, 56.25%, 57.1%, 49%; 45% in Nigeria, Ada'a district of Oromia region in Ethiopia, in Algeria; in Delmarva, Maryland, and Northwestern part of Ethiopia respectively. This variation might be due to vaccination in those developed countries where ILT vaccination is utilized.…”

“…Among the host-related risk factors, only breed showed a significant association with seroprevalence (p<0.05). Sasso breed chickens had 9.68 times more likely in the odds of seropositivity as compared to local breed and Bovans exotic breeds (AOR: 9.68, 95%CI: 1.96 -47.78) This study was in line with finding of Birhan et al, (2022) who reported that local chickens had a 62% reduction in the odds of seropositivity as compared to exotic breed. Studies have shown that local breeds of chickens have better environmental adaptability and disease resistance traits than exotic breeds (Wong et al, 2017).…”

“…In this study, seroprevalence varied significantly (p < 0.05) among the different study sites, with the highest seroprevalence recorded in Nekemte town followed by Guto Gida, Diga and the least in Leka Dulecha. Similarly, Bhuiyan et al, (2019), Roba et al, (2020 and Birhan et al, (2022) reported a significant variation in prevalence of ILTV between the different study areas they considered. Differences in management practices including biosecurity and vaccination could explain the differences in different study areas.…”

“…Clinically it is characterized by dyspnea and gasping with an extension of the head and neck. Coughing, rattling, and gurgling also noticed when the birds try to expel the clotted blood and debris from the obstructed trachea (Blakey et al, 2019). Severe form of the disease results in respiratory depression, gasping, and expectoration of bloody exudates with high rates of morbidity and mortality up to 70% in an acute form of infection (Parra et al, 2016).…”

“…Only few reports are existing in the country. For instance, in recent years, Tesfaye et al, (2019) andRoba et al, (2020) reported serological evidence of ILTV infection in Central and South Ethiopia (19.4%) and Ada'a district in Oromia region (54.7%), respectively and additionally (Birhan et al, 2022) reported prevalence of ILTV infection (59.1%) in central Gondar, West Gojjam, and South Gondar of Amhara regional state, northwestern Ethiopia. This disease causes production losses due to increased morbidity, moderate mortality, decreased weight gain, reduced egg production and expenses spent on vaccination, biosecurity measures and therapy to counteract secondary infection by other avian pathogens (Guy and Bagust 2003;Guy and Garcia 2008;Jones 2010;Garcia et al, 2014).…”