They are the first line of defence against the Covid-19 pandemic, but in parts of Mexico, doctors, nurses and other health workers are being harassed to the point that federal authorities have pleaded for Mexicans to show solidarity.

While tributes to courageous medical personnel putting themselves in the virus' path circle the globe, Mexico and some other places have seen disturbing aggression born of fear.

Recently, a hospital in Guadalajara Mexico's second-largest city were told to wear civilian clothes to and from work rather than their scrubs or uniforms because some public buses refused to allow them to board. Other medical personnel have reported attacks and this week, someone threw flammable liquid on the doors of a new hospital under construction in the northern border state of Nuevo Leon.

"There have been cases, you could say isolated, but all outrageous," Mexican undersecretary of health Hugo Lopez-Gatell said on Monday night.