What ill-effects have there been on the ecosystem due to eradication of smallpox?

We have always been taught that ecosystems have delicate balances that can be disturbed by the removal or extinction of a single species irrespective of how large or small the creature is. In the 1980’s the WHO eradicated the smallpox virus by means of an extensive vaccination program. My question is due to the eradication of this virus have there been any ill-effects on the ecosystem?
If yes, then isn’t eradicating a virus for human health and safety detrimental to the very cause we are trying to fulfill as it will disrupt natural ecosystems?