Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe human infections and dromedary camels are considered an intermediary host. The dynamics of natural infection in camels are not well understood. Through systematic surveillance in Egypt, nasal, rectal, milk, urine and serum samples were collected from camels between June 2014 and February 2016. Locations included quarantines, markets, abattoirs, free-roaming herds and farmed breeding herds. The overall seroprevalence was 71% and RNA detection rate was 15%. Imported camels had higher seroprevalence (90% vs 61%) and higher RT-PCR detection rates (21% vs 12%) than locally raised camels. Juveniles had lower seroprevalence than adults (37% vs 82%) but similar RT-PCR detection rates (16% vs 15%). An outbreak in a breeding herd, showed that antibodies rapidly wane, that camels become re-infected, and that outbreaks in a herd are sustained for an extended time. Maternal antibodies titers were very low in calves regardless of the antibody titers of the mothers. Our results support the hypothesis that camels are a reservoir for MERS-CoV and that camel trade is an important route of introducing the virus into importing countries. Findings related to waning antibodies and re-infection have implications for camel vaccine development, disease management and zoonotic threat.

Highly pathogenic avian influenza (HPAI) H5N1 and low pathogenic avian influenza (LPAI) H9N2 viruses have been recognized as threats to public health in Bangladesh since 2007. Although live bird markets (LBMs) have been implicated in the transmission, dissemination, and circulation of these viruses, an in-depth analysis of the dynamics of avian transmission of H5N1 and H9N2 viruses at the human–animal interface has been lacking. Here we present and evaluate epidemiological findings from active surveillance conducted among poultry in various production sectors in Bangladesh from 2008 to 2016. Overall, the prevalence of avian influenza viruses (AIVs) in collected samples was 24%. Our data show that AIVs are more prevalent in domestic birds within LBMs (30.4%) than in farms (9.6%). Quail, chickens and ducks showed a high prevalence of AIVs (>20%). The vast majority of AIVs detected (99.7%) have come from apparently healthy birds and poultry drinking water served as a reservoir of AIVs with a prevalence of 32.5% in collected samples. HPAI H5N1 was more frequently detected in ducks while H9N2 was more common in chickens and quail. LBMs, particularly wholesale markets, have become a potential reservoir for various types of AIVs, including HPAI H5N1 and LPAI H9N2. The persistence of AIVs in LBMs is of great concern to public health, and this study highlights the importance of regularly reviewing and implementing infection control procedures as a means of reducing the exposure of the general public to AIVs.

An aggressive plan to curb these infections in poultry is urgently needed.

Human infection with avian influenza A(H9N2) virus was identified in Bangladesh in 2011. Surveillance for influenza viruses in apparently healthy poultry in live-bird markets in Bangladesh during 2008–2011 showed that subtype H9N2 viruses are isolated year-round, whereas highly pathogenic subtype H5N1 viruses are co-isolated with subtype H9N2 primarily during the winter months. Phylogenetic analysis of the subtype H9N2 viruses showed that they are reassortants possessing 3 gene segments related to subtype H7N3; the remaining gene segments were from the subtype H9N2 G1 clade. We detected no reassortment with subtype H5N1 viruses. Serologic analyses of subtype H9N2 viruses from chickens revealed antigenic conservation, whereas analyses of viruses from quail showed antigenic drift. Molecular analysis showed that multiple mammalian-specific mutations have become fixed in the subtype H9N2 viruses, including changes in the hemagglutinin, matrix, and polymerase proteins. Our results indicate that these viruses could mutate to be transmissible from birds to mammals, including humans.

Results of this study indicate that the number of humans infected with avian influenza viruses is much larger than the number of reported confirmed cases. In an area where these viruses are enzootic in the poultry, human exposure to and infection with avian influenza becomes more common.