您好，【无法估算有多少居民受到疾病侵袭】（含estiamte）的翻译可以考虑：
1）It is impossible to estimate how many residents have been affected by the disease.
2）It is impossible to estimate how many inhabitants have been affected by the illness.
3）It is impossible to estimate as to how many dwellers have been struck down by the malady.
这里 residents、inhabitants、dwellers 都可以译为（居民）需要看情景；disease、illness、malady 都可以译为（疾病）。
假如（无法估计）可以使用 estimate 的其他形式，还可以考虑 inestimatable 这个英语单词；
1）It is inestimable as to how many residents have been struck down by the disease.
annywong1990
