Microsoft co-founder Bill Gates is being targeted and harassed on social media in the wake of his comments criticizing the federal response to the coronavirus pandemic and the U.S. decision to withdraw funds from the World Health Organization.

On a recent Instagram post thanking health care workers, the billionnaire philanthropist was subjected to hundreds of thousands of comments calling him a partisan and linking him to a wide range of bizarre conspiracy theories.

Gates is no stranger to online trolls, but the attacks against him have intensified recently. The Gates Foundation is the second-largest financial backer of the WHO after the United States. The organization has also committed about $250 million for research and testing related to COVID-19.

Facebook, which owns Instagram, already prohibits harassment and coordinated inauthentic activity.

“We’re looking at this behavior carefully to determine whether it violates our policies. People on our services are allowed to speak freely, and do so in an organized way, but we remove accounts that are fake or designed to mislead. We also remove comments that violate our Community Guidelines, such as hate speech or death threats,”a Facebook spokesperson told Fox News via email.

At this early stage, it does not appear that the harassment against Gates is being made by inauthentic or fake accounts, according to a company source familiar with the matter.

The Wall Street Journal reports that Gates' post from April 5 drew an additional 45,000 comments in the 24-hour period after he critiqued America's defunding of the WHO. His Twitter account was mentioned more than 270,000 times in that same 24-hour period, according to the newspaper.

Mark Suzman, CEO of the Gates Foundation, provided Fox News with the following statement via email:

"We’re concerned about the conspiracy theories being spread online and the damage they could cause to public health. At a time like this, when the world is facing an unprecedented health and economic crisis, it’s distressing that there are people spreading misinformation when we should all be looking for ways to collaborate and save lives. Right now, one of the best things we can do to stop the spread of COVID-19 is spread the facts."