Background While Campylobacter jejuni represents the most common cause of bacterial gastroenteritis, Yersinia pseudotuberculosis infections are very rarely diagnosed in adults. Case We report on a previously healthy patient who presented several times at our hospital with fever, Guillain-Barré syndrome, recurrent abdominal symptoms and distinct mesenteric lymphadenopathy, respectively. This complicated and diagnostically challenging course of disease was caused by a C. jejuni and Y. pseudotuberculosis coinfection. Antibiotic treatment with doxycycline was effective. Conclusion Broad serology testing was crucial to discover that two concomitant infections were causing the symptoms. This case demonstrates that when a clinical picture is not fully explained by one known infection, another infection with the same underlying risk factor has to be considered, hence “a horse and a zebra”.