Related by context. Frequent words. (Click for all words.) 76 mutate 70 mutating 61 mutated 58 morphs 55 evolves 52 infects 47 pandemic strain 45 morph 45 flu viruses 45 morphing 44 influenza viruses 44 transforms 44 infect humans 43 virulent 43 flu virus 43 resurfaces 43 influenza virus 43 organism 42 grows 42 malaria parasite 42 infect 41 adapts 41 disappears 41 migrates 41 accumulates 41 reappears 41 flu strains 40 bacterium 40 learns 40 merges 40 multiplies 40 decays 40 reproduces 40 viruses 40 melts 39 propagates 39 seduces 39 escalates 39 erupts 39 H#N# strain 39 turns 39 recurs 39 disintegrates 39 meanders 39 becomes 39 progresses 39 spreads 39 invades 39 mutation 39 unravels 39 explodes 38 virus 38 dissipates 38 highly contagious 38 develops 38 incites 38 unpredictably 38 discovers 38 glides 38 mutant 38 bird flu virus 38 devolves 38 unleashes 38 infecting 38 creeps 38 conquers 38 descends 38 occurs naturally 37 evolve 37 humans 37 spins 37 manifests itself 37 invents 37 thickens 37 pandemic 37 mutations 37 veers 37 provokes 37 contagious disease 37 emerges 37 contagious 36 disperses 36 fizzles 36 replicates 36 germ 36 disarms 36 microbe 36 segues 36 weaves 36 behaves 36 parasite 36 plucks 36 infectious 36 lurches 36 epidemics 36 penetrates 36 drug resistant strains 36 wanders 36 pathogen 36 spawns 36 scatters