The fact that the H7N9 virus has only recently infected humans helps explain why

Because the H7N9 avian virus acquired pathogenic mutations in order to infect mammalian hosts

Explanation:

H7N9 is a subtype of influenza avian viruses that has recently been reported to infect humans. Fortunately, H7N9 has also been reported to have a low pathogenic level; however, mutations might change this level to become more infectious for humans. Consequently, mutations in a given H7N9 strain might enable its adaptation and higher affinity to human-type receptors, being more aggressive to human cells, especially in lung cells, since this virus is characterized by rapid progression and respiratory failure.

explanation:

for example, code 28039 - excision, tumor, soft tissue of foot or toe, subcutaneous, 1.5 cm or greater, appears before 28043 - excision, tumor, soft tissue of foot or toe, subcutaneous; less than 1.5 cm.

answer:

i honestly don't know. but for being kind and considerate and trying to make people feel better! people like you show the world that their is still always kindness going around. it means a lot to me (and others! ) that you are trying to cheer people up. we need more people like you! < 3 < 3 < 3

explanation:

spread the love with #notahater !