I just took a look at those references and they don't site a study where researchers actually went and counted males and females with Crohn's. All three of those sources, as authoritative as they look, might just be copying from each other. It also looks like it's wrong info...
Here's a link to
Inflammatory bowel disease prevalence by age, gender, race, and geographic location in the U.S. military health care population. Inflamm Bowel Dis. 2013 Jun;19(7):1421-7. doi: 10.1097/MIB.0b013e318281334d
Here's what it says:
METHODS:
Using International Classification of Diseases, Ninth Revision codes, patients with Crohn's disease (CD) and ulcerative colitis (UC) seen within the military health care system (Tricare) from October 1, 2008 to September 30, 2009 were identified. This database comprised all active duty military, retirees, and dependents. The overall prevalence of IBD, UC, and CD was calculated, and the prevalence by age, gender, race, and geographic location.
RESULTS:
A total of 35,404 cases of IBD were identified in 10.2 million military health care beneficiaries establishing a prevalence of total IBD, UC, and CD of 348, 202, and 146 per 100,000, respectively. IBD was more prevalent in females compared with males (417 versus 284 per 100,000; relative risk, 1.53; 95% confidence interval, 1.50-1.57). There was an increased prevalence of IBD with each decade of life....