Prolonged Abdominal Complaints in Travellers

Prolonged abdominal complaints caused by intestinal pathogens

• Bacterial pathogens
  • The most common cause of acute diarrhoea (in travellers about 80% bacterial; see Acute Diarrhoeal Disease in a Traveller)
  • Long-term carriers may exist but are not common (most significant in practice in salmonellosis)
  • In 1-3% of patients with acute gastroenteritis abdominal symptoms become prolonged.
  • EPEC and EAEC (enteropathogenic and enteroaggregative E. coli) may sometimes be associated with prolonged symptoms.
• Viruses
  • Cause acute disease; prolonged symptoms are rare.
  • Asymptomatic excretion of viruses may continue for several weeks or even several months after the acute infection (particularly in those with immunodeficiencies).
• Intestinal protozoans
  • The longer the symptoms continue, the more probably they are caused by protozoans.
  • In the beginning, the infection is often either asymptomatic or produces few symptoms.
  • The most common causes are Dientamoeba fragilis Dientamoebiasis in Adults and Giardia lamblia Giardiasis.
  • Entamoeba histolyticaAmoebiasis usually causes more severe diarrhoea than the above and symptoms often include blood in stools and sometimes also fever.
  • In prolonged Cryptosporidium Cryptosporidiosis, Cyclospora Introduction to Intestinal Protozoal Diseases and Cystoisospora infections Introduction to Intestinal Protozoal Diseases and microsporidiosis, there is often immunodeficiency as a predisposing factor, such as advanced HIV infection or immunosuppressive medication. Also rarer pathogens are seen in patients with immunodeficiencies.
• Intestinal worms
  • The infection is often either asymptomatic or produces few symptoms.
  • Strongyloides stercoralisStrongyloidiasis (the most common cause of symptomatic worm infections in travellers), Ascaris lumbricoides, or roundworm Ascariasis, hookworms Hookworm Disease and Trichuris trichiura Trichuriasis cause the most symptoms.
  • Other worms cause symptoms only at a high worm load; in practice these are seen only in people who have lived very long in endemic areas.

Antibiotic-associated diarrhoea (symptoms related to the use of antimicrobial drugs)

• Occurs in 5-25% of patients on antimicrobial drugs.
• In some, symptoms occur already a few hours, in others as long as several weeks after the initiation of the medication.
• Antimicrobial drugs destroy the patient's own intestinal microbes, broad-spectrum antimicrobials more so than narrow-spectrum antimicrobials.
• Microbial imbalance may appear as overgrowth of Clostridium difficile bacteria, for example.
• Clostridioides difficileClostridioides Difficile Diarrhoea
  • Only toxin-producing strains cause diarrhoea.
  • May present as asymptomatic colonization.
  • Life-threatening pseudomembranous colitis is the most severe form of the disease.

Non-infectious abdominal complaints triggered by microbes

• Microbes may sometimes trigger a non-infectious disease even if the causative agent can no longer be shown after prolonged symptoms. Acute gastroenteritis, for example, may trigger a chronic inflammatory bowel disease, such as Crohn's disease Crohn's Disease or ulcerative colitis Ulcerative Colitis.
• Symptoms may persist for as long as several months.
• Secondary malabsorption in some protozoal diseases, such as giardiasis
  • May be due to damaged intestinal villi.
  • The most common form of secondary malabsorption is secondary lactose intolerance, a state of disease sometimes resembling coeliac disease.
  • The symptoms will subside as the intestinal villi recover.
• Postinfectious irritable bowel syndrome, PI-IBS Functional Bowel Disorders and the Irritable Bowel Syndrome (Ibs)
  • The diagnosis is made by excluding other causes of prolonged abdominal complaints.
• Postinfectious malabsorption syndrome, PI-MAS, or tropical sprue
  • Seen in people who have stayed a long time in tropical areas.
  • May present as severe malabsorption; the patient may lose a significant amount of weight.
  • May continue for several months.
  • Very rare in travellers
  • The diagnosis is made by excluding other causes.

Noninfectious causes

• Coeliac disease Coeliac Disease
• Lactose intolerance Lactose Intolerance
• Hyperthyroidism Hyperthyroidism
• Irritable bowel syndrome, IBS Functional Bowel Disorders and the Irritable Bowel Syndrome (Ibs)
• Inflammatory bowel diseases: Crohn's disease Crohn's Disease, ulcerative colitis Ulcerative Colitis
• Colorectal cancer Colorectal Cancer

Bacterial causes

• If aetiological investigations are needed, the basic study is either faecal bacterial culture or a more extensive combination of nucleic acid detection and culture.
• Bacteria identified by both of these tests:
  • Salmonella
  • Shigella
  • Yersinia
  • Campylobacter
• Detection of nucleic acids of faecal pathogens using a gene amplification method is more sensitive and faster than culture. In addition to the afore-mentioned bacteria, it can detect the following:.
  • Escherichia coli strains causing diarrhoea:
    • enteroaggregative (EAEC)
    • enteropathogenic (EPEC)
    • enterotoxigenic (ETEC)
    • enteroinvasive (EIEC)
    • enterohemorrhagic (EHEC) E. coli.
  • For any sample for which the nucleic acid detection method gives a positive result for Salmonella, Shigella, Yersinia, Campylobacter or EHEC, a culture and, if needed, sensitivity testing, are done without separate request.
• Serological methods (Salmonella, Campylobacter and Yersinia antibodies) are used
  • when the symptoms have continued for more than 2 weeks and the aetiology is still not known
  • when reactive arthritis is suspected
  • when investigating prolonged unclear episodes of fever
  • when general symptoms occur.
• In patients who have taken antimicrobials, nucleic acid detection test for Clostridium difficile is also performed. Nucleic acid detection is a sensitive test and should not be used in persons with no symptoms. In children below 2 years of age, C. difficile is a part of normal intestinal flora.

Biphasic diagnosis of parasitic infections

In Finnish patient samples protozoans are the most common parasites. Dientamoeba is clearly more common than Giardia. Since the introduction of nucleic acid detection tests, also Cryptosporidium findings have increased significantly, but especially the increased number of findings in 2018-2019 is suggestive of an increase in the number of infections (in 2019 almost 500 cases per year in a population of 5.5 million). Intestinal worms are clearly more rare findings than protozoans. In biphasic diagnosis, protozoans are first looked for and intestinal worms only in the second phase.