CBC News learned this week that the provincial health-care provider is eliminating dedicated case managers for people with those chronic diseases.
The 230 patients will instead be handled by general case managers within the home-care system, officials said.
"Personally I'm fearful," said Jacki Capper, president of the United Nurses of Alberta Local 211 Calgary Community.
Capper is one of the home-care case managers who will be taking on the ALS and MS patients affected by the cuts.
"The change is going to be the quality of safe patient care. There isn't going to be the ability to deliver that same care. They're going to lose out in the end," she said.
Capper said most home-care case managers already have caseloads of 50 to 65 patients.
"I’m not sure what studies would have shown that there is capacity, because there is not capacity. There isn't a home-care case manager sitting there waiting for work. They're all busy. They're already over capacity within their own workloads," she said.
"So I don't know how this additional workload will be managed."
Liberal Health Critic David Swann said the decision will be a costly one.
"It's going to cost more in the system because there are going to be more emerg room visits, there are going to be more hospitalizations," he said.
"People are going to get into more complex situations because they didn’t have the early identification of a problem and the early treatment of a problem."
Critics have also said some ALS and MS patients could end up with no case manager at all, since not all people with those diseases qualify for home care.
Union officials said they have been told by AHS only patients who qualify for home care will be transferred over to general case managers.