Marek was born on March 18, 1868, in the village then known as Vágszerdahely, Nyitra County in the Kingdom of Hungary (today Horná Streda in Slovakia).

[4] In 1897, Marek was offered a position at the veterinary college in Budapest as a clinical assistant, equivalent to an adjunct professor.

[5] As it was required that teachers at the veterinary college held an advanced qualification, at the behest of his superiors, Marek went to the University of Bern in Switzerland in May 1897 to study for his doctorate, which he was awarded in April 1898.

[8] Working with Pál Pataki, he developed Distol, a proprietary remedy for the treatment of liver fluke in cattle, which was manufactured at the Chinoin Pharmaceutical Factory.

[11] With Ferenc Hutÿra, Marek co-authored a two volume textbook in German, Spezielle Pathologie und Therapie der Haustiere (Special pathology and therapeutics of the diseases of domestic animals).

[1] It became a standard text in many countries,[6] and was fully translated into Chinese, English, French, Italian, Polish, Russian, Serbian, Slovak, Spanish, Turkish,[1][5] and partially into Finnish.

[5] In December 1931, the Budapest Royal Medical Association (Budapesti Királyi Orvosegyesület) awarded the Balassa Prize to Marek for his work on rickets.

[17] As part of the commemorations of 200 years of veterinary education in Hungary, a stamp was issued bearing Marek's portrait on May 25, 1987.