Emergence and dynamics of XXXX super-strains.

@entity1 @entity1707 @entity281 @entity683
BACKGROUND: Influenza super-strains can emerge through recombination of strains from birds, @entity1707 , and @entity1 . However, once a new recombinant strain emerges, it is not clear whether the strain is capable of sustaining an outbreak. In certain cases, such strains have caused major @entity683 pandemics. METHODS: Here we develop a multi-host (i.e., birds, @entity1707 , and @entity1 ) and multi-strain model of @entity683 to analyze the outcome of emergent strains. In the model, @entity1707 act as "mixing vessels" for avian and @entity1 strains and can produce super-strains from genetic recombination. RESULTS: We find that epidemiological outcomes are predicted by three factors: (i) contact between @entity1707 and @entity1 , (ii) transmissibility of the super-strain in @entity1 , and (iii) transmissibility from @entity1707 to @entity1 . Specifically, outbreaks will reoccur when the super-strain @entity281 are less frequent between @entity1 (e.g., R0=1.4) but frequent from @entity1707 to @entity1 , and a large-scale outbreak followed by successively damping outbreaks will occur when @entity1 transmissibility is high (e.g., R0=2.3). The average time between the initial outbreak and the first resurgence varies from 41 to 82 years. We determine the largest outbreak will occur when 2.3 <R0 < 3.8 and the highest cumulative @entity281 occur when 0 <R0 < 3.0 and is dependent on the frequency of @entity1707 -to- @entity1 @entity281 for lower R0 values (0 <R0 < 1.9). CONCLUSIONS: Our results provide insights on the effect of species interactions on the dynamics of @entity683 super-strains. Counter intuitively, epidemics may occur in @entity1 even if the transmissibility of a super-strain is low. Surprisingly, our modeling shows strains that have generated past epidemics (e.g., H1N1) could resurge decades after they have apparently disappeared.
