Dr Wendy Armstrong of HIV Medicine Association also disputed the need to develop new treatments for toxoplasmosis.
"This is not an infection where we have been looking for more effective drugs," she told Infectious Disease News.
On Wall Street, biotech shares fell sharply on Monday after Democratic presidential candidate Hillary Clinton pledged to take action against firms hiking prices for specialty drugs.
"Price gouging like this in the specialty drug market is outrageous," Mrs Clinton said, citing Daraprim.