A bed bug infestation at a London school highlights how difficult the pests are to get rid of, and how social inequality is brought into the classroom.

The bugs were found on two occasions at the same school, days apart, in late January, CBC News has learned.

Bed bugs are considered a nuisance by the school board and health unit -- gross and annoying, but not a health hazard, much like head lice, officials say.

But head lice are a much more common occurrence and require only that a note be sent home telling parents to check their kids hair.

Bed bugs require that and much more: classrooms or affected areas to be deep cleaned by custodians, then fumigated or otherwise cleaned by a professional exterminator, school board officials said. 

"There's a social stigma around bed bugs," said Paul Sydor, a superintendent with the Thames Valley District School Board.

"There are feelings of upset and anger and shame, and that's why we try to keep it as low key as possible," Sydor said.

The bed bugs were found in a school on two days in January. 

The last time there was a bed bug incident was in 2016. 

Bed bugs in London

Bed bugs were found in a London school in January. (Supplied)

This one happened on two occasions in January.

It was reported to the school board and the teachers' union health and safety representative, said Craig Smith, the local president of the Elementary Teachers' Federation of Ontario.

"The main concern is isolating it and making sure it doesn't spread but the other main issue is the children involved in that school and classroom," Smith said.

"There's a broader social issue here. When bed bugs are in homes or apartments of people with means, they can be attended to. In communities where there isn't the social capital or the resources to attend to it it's more difficult. A lot of things that happen in the broader community happen in schools."

Bed bugs are difficult to get rid of because they're becoming immune to the most commonly-used pesticides, said Jamie Drennan, owner of ASAP Pest Control Inc. in London.

Entire rooms have to be treated, he added. ASAP Pest Control Inc. has had to start using a new family of chemicals to kill the bugs.  

Sometimes an apartment unit will have a few bed bugs but adjoining units will have an infestation, Drennan said.

Officials did not identify the school at which bed bugs were found because of the social stigma.