Crohn’s after visiting tropical country

36 y.o male whose Crohn's disease appeared a few days after a trip to Colombia


Everyone’s microbiome has been shaped by several factors. Starting from our mother’s vaginal microbiome during birth to the amount of antibiotics we have consumed throughout our life, the microbiome is constantly changing. One factor that makes the microbiome of a specific population being kind of similar is geographic location and the culinary habits of a nation. In this context, Japanese have a completely different microbiome than Mexicans do. And while raw fish is very common in Japan, a Mexican will probably experience gastrointestinal disturbances after that sushi. In several cases, a sudden shift in the diet of a person could produce massive changes in his microbiome, even bring into surface a predisposition for autoimmunity.

Gaulke, Christopher A., and Thomas J. Sharpton. “The influence of ethnicity and geography on human gut microbiome composition.” Nature medicine 24.10 (2018): 1495-1496.

Rehman, Ateequr, et al. “Geographical patterns of the standing and active human gut microbiome in health and IBD.” Gut 65.2 (2016): 238-248.


Jim C. was a perfectly healthy 36 years old swimmer who had never experienced any gastrointestinal symptoms. From his medical history, the only time his stomach bothered him was during a gastroenteritis when he was 9 years old. That’s all he could remember. He loved surfing and travellling around the world. His last trip was in Colombia. Before traveling he got the recommended yellow fever vaccine. He did not report any side effects from the vaccine. 15 days later he returned from Colombia and the only incident he can remember is being bitten by several mosquitos during an inland excursion. A few days later he noticed his lower abdomen swelling, but the swellling was constantly moving, until his testicles got swelled as well. The swelling insisted for about a week and then resolved on its own.

The only thing that led Jim to visit a doctor was the slight change in stool shape. The gastroenterologist performed several blood tests and noted an elevation in CRP value, which was reproduced 10 days later. Then he ordered a calprotectin test (880) with the result indicating massive leukocyte activation. The diagnosis was ultimately confirmed afte the colonoscopy, which revealed a Crohn’s disease image that certainly did not match the lack of GI symtpoms. He started prednisone and mesalasine and two months later he came to see me in my office. 

The course of the treatment could not be monitored since Jim had no symptoms at all. This is rare but I have seen it before. Jim had just finished his first treatment and was asked to repeat calprotectin. The value was much better but not normal (336). I decided to take it a step forward.

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Jim had been exposed to a completely different diet during his trip to Colombia. Maybe this is not enough to bring into surface an autoimmune disorder, but in an already predisposed person, genetically or environmentally, such a violent microbiome rearrangement could do the job.


Parasitic infections may mimic IBD both clinically and diagnostically

The sudden urge to defecate may be a symptom of IBD, but also of a potent parasitic infection 

The immune augmentation in order to fight a parasitic infection is extremely energy-consuming

Mucus is the first line of gastrointestinal passive defense and increases during an active infection

Testicular swelling prior to diagnosis

Mohammadi, Rasoul, et al. “The relationship between intestinal parasites and some immune-mediated intestinal conditions.” Gastroenterology and hepatology from bed to bench 8.2 (2015): 123.


The probiotic sterility was pronounced, and so was the other two inflammation markers, besides calprotectin (EPX and sIgA). The most prominent, though, finding was too many Blastocystis hominis full parasites as well as trophozoites. In addition, several strains of Citrobacter were recovered in vast amounts. 

Actionable exam results

Blastocystis hominis

Parasites like Blastocystis have long been suspected to be involved in the pathogenesis of inflammatory bowel diseases

Elevated sIgA

Elevated immunoglobulin A is indicative of a chronic infectious inflammatory reaction. Serum IgA was within normal range

Citrobacter spc​

Too many Citrobacter species means constant alkalinization of the mucosal surfaces due to ammonia production

Vitamin D deficiency

Vitamin D is crucial in all autoimmune disorders, including Crohn’s colitis


This is a very sensitive eosinophil activation biomarker.


Parasites are hard to eliminate. Despite the mainstream view, protozoa like B. hominis can’t get eliminated using just metronidazole. Nevertheless, a 10-day antiparasitic course, repeated 3 times during a 3-month time window will certainly be more effective, under the condition that all other aspects of the disease are equally covered. In this case, the presence of too many gram-negative bacilli (Citrobacter) dictated simultaneous antibiotic treatment, at least during the first metronidazole treatment. A third pharmaceutical, appropriate in this case is budesonide. The large amount of activated eosinophils, probably due to the parasitic overabundance, should be quenched. 

Follow up

In Jim’s case, it was first provided after the first month of antibiotic treatment, and indeed, that is when he felt much better, his urgency episodes disappeared and his stool were completely formed. Finally, a large dose of vitamin D was given, until his serum value reached above 60 (63,3). Jim was able to discontinue prednisone without relapse and stay on mesalazine and an intermittent schedule of budesonide (twice per year for 2 months). His last colonoscopy was clear, without any sign of a relapse and he experiences less fatigue.

Theodoros Prevedoros
With extensive experience evaluating over 3000 cases in various specialties, including gastroenterology, pediatrics, and endocrinology, Theodoros has collaborated with more than 25 doctors from Greece and Cyprus and over 10 laboratories worldwide.

With a background in Chemistry and Biochemistry from the National and Kapodistrian University of Athens, Theodoros brings a wealth of knowledge in functional medicine and advanced treatments to his role. He possesses exceptional skills in analysis, pattern recognition, diagnostic translation, and storytelling. He is also FMU certified in Functional Medicine and has received training in advanced treatments from the Saisei Mirai Clinic in Japan.