Age-Related Susceptibility to Japanese Encephalitis Virus in Domestic Ducklings and Chicks

Abstract

Abstract. Ardeid birds and pigs are known as major amplifying hosts for Japanese encephalitis virus, and ducklings and chickens have been considered to play at best a minor role in outbreaks because of their low or absent viremia. We hypothesized that viremia of sufficient magnitude would develop in young ducklings (Anas platyrhynchos) and chicks (Gallus gallus) for them to serve as reservoir hosts and thereby contribute to the transmission cycle. Infection was associated with reduced weight gain in both species, and ducklings infected at 10 days of age or less showed overt clinical signs of disease. The mean peak viremia in birds of both species decreased as the age at infection increased from 2 to 42 days, indicating the importance of age of infection on magnitude of viremia in birds from both species, and suggesting that young poultry may be amplifying hosts of importance in disease-endemic regions.

Intensive Circulation of Japanese Encephalitis Virus in Peri-urban Sentinel Pigs near Phnom Penh, Cambodia

“…This difference may translate a different combination of hosts, vectors and agricultural practices in the two areas, pointing out the importance of taking into account these parameters when planning control programs [17]. In the absence of wild waterbirds in periurban and urban areas, domestic and peridomestic species such as passerine birds may play a role in the transmission and the maintenance of the virus as suggested by the JEV viremia experimentally observed in poultry [15] and in several native North American passerine species [16]. …”

“…The main vectors such as Culex tritaeniorhynchus breed mostly in rural settings, however, other species like Culex quinquefasciatus , an anthropophilic species, could play an a role in JE transmission in periurban or urban areas [12,13]. Beyond the aquatic wild birds traditionally suspected to be the main reservoir [5,14], several host species are also thought to be able to play a role in the transmission of the virus such as poultry or non-aquatic wild birds such as passerine birds that experimentally show sufficient viremia to allow virus transmission [15–17]. This means that JE could be transmitted and even maintained in a wide range of environments beyond the typical rural, paddy-fields dominated landscape.…”

Detection of Japanese Encephalitis Virus in bone marrow of healthy young wild birds collected in 1997–2000 in Central Italy

“…Experimental subcutaneous infection of ducklings and chicken with JEV has shown that youngest animals were more susceptible to the infection than older animals and that the mean peak viremia in birds of both species decreased as the age at infection increased from 2 to 42 days, suggesting that young poultry may be amplifying hosts of importance in disease‐endemic regions (Cleton, Bosco‐Lauth, Page, & Bowen, ). In our study, young birds resulted infected by JEV were younger than 2 months and thus they were born probably when episodes of bird mortality occurred in Tuscany.…”

Japanese Encephalitis, Recent Perspectives on Virus Genome, Transmission, Epidemiology, Diagnosis and Prophylactic Interventions

“…cattle egrets and pond herons) act as important natural reservoirs as well as maintenance hosts for JEV and may also be responsible for the spread of JEV in virgin soil (Upadhyay & Ahmad, 2011). Adult ducks and chickens are also susceptible to infection with JEV with low viremia but unlikely to substantial transmission to feeding mosquitoes (Cleton et al, 2014). However, hatched chicks might develop much higher viremia than adult birds which suggests their minor role in JEV transmission in endemic regions.…”