Avian Influenza and Newcastle Disease in Three Risk Areas for H5N1 Highly Pathogenic Avian Influenza in Mali, 2007–2008

Abstract

Our survey aimed to investigate avian influenza (AI) and Newcastle disease (ND) prevalence and risk factors in three areas of Mali at risk for occurrence of H5N1 highly pathogenic avian influenza. Blood samples and cloacal and oropharyngeal swabs were collected from 1470 birds between February 2007 and May 2008 and were tested by commercial enzyme-linked immunosorbent assay to detect antibodies and real-time reverse-transcription (rRT)-PCR to detect virus. Risk factors associated with seropositivity or positive rRT-PCR were identified by random effect logistic regression. AI seroprevalence was significantly lower in birds from commercial farms (0%) than in village backyard birds (3.1%). For backyard birds, no individual risk factors (species, age, sex) were identified, but birds in the Mopti area in the Sahelian zone, where millions of wild birds migrate, were more seropositive than in the Sikasso area in the Sudano-Guinean zone (odds ratio [OR] = 2.0, P = 0.051). Among backyard birds nonvaccinated against ND, ND seroprevalence was 58.4%, and the odds of seropositivity was 2.0 higher in chickens than in ducks, 1.7 higher in females than in males, 3.1 higher in adults than in young birds, and 3.0 higher in poultry from the Sikasso area than from the Mopti area (P < 0.01 in all cases). Prevalence established by rRT-PCR was low for both AI virus (1.1%) and ND virus (2.6%) and was associated with no risk factors for AI but was higher in chickens than in ducks (OR = 5.3, P = 0.05) and in the Sikasso area than in the Mopti area (OR = 3.4, P = 0.027) for ND. For AI and ND, prevalence assessed by serology or rRT-PCR varied over time, although seasonal and interannual variation could not be clearly distinguished. The intracluster correlation coefficient for serologic data was low for AI (0.014) and higher for ND (0.222). These results are useful to optimize surveillance and control strategy for notifiable avian diseases in African countries with similar agroecological and resource-limited contexts.

Risk Factors and Characteristics of Low Pathogenic Avian Influenza Virus Isolated from Commercial Poultry in Tunisia

“…However this may not be the only explanation for monthly variations as seroprevalence remained over 25% in January and March, with broilers representing 64% and 62% of the flocks sampled at that period of time. It has also been suggested that AIV prevalence may vary with contacts between poultry and wild birds and virus survival under environmental conditions, including temperature [31]. At last, between-flock seroprevalence might also be influenced by the seasonality of poultry production and trade in Tunisia.…”

Serological Evidence of West Nile and Usutu Viruses Circulation in Domestic and Wild Birds in Wetlands of Mali and Madagascar in 2008

“…In Mali, the same cross-sectional prevalence survey was carried out in May 2008 on chickens and ducks. This period corresponds to the end of the dry-hot season, with an average temperature of 32 • C. The whole protocol design is described in [49]. The study population was the backyard poultry population of villages known to raise ducks by the agents of the Regional Directorates of Veterinary Services of Mopti.…”

“…The study population was the backyard poultry population of villages known to raise ducks by the agents of the Regional Directorates of Veterinary Services of Mopti. Villages and farms were conveniently chosen, based on accessibility criteria and owners' willingness [49].…”

Experimental co-infections of domestic ducks with a virulent Newcastle disease virus and low or highly pathogenic avian influenza viruses

“…Natural co-infections of NDV and LPAIV have been documented numerous times in wild waterfowl and in domestic poultry (Couacy-Hymann et al, 2012; Dormitorio et al, 2009; Hanson et al, 2005; Molia et al, 2011; Rosenberger et al, 1974; Roussan et al, 2008; Shortridge, 1980). However, little is known on the interactions between these two viruses when simultaneously infecting poultry species including domestic ducks.…”