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Case-based MCQ | #Case_451 | #answer
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E
Travellers to developing countries with high incidence of infectious diarrhea may develop diarrhea (
traveller’s diarrhea) during their stay in those countries or after arrival in their home country. Traveller’s diarrhea may be caused by bacteria, viruses or parasites especially protozoa. The diarrhea may be either inflammatory or non-inflammatory or may be watery or in the form of dysentery depending on the causative organism. The likely cause of traveller’s diarrhea can inferred from knowledge of the usual causes of diarrhea in the region visited, temporal relationship between development of diarrhea and visit as well as the clinical features of the disease.
Giardia lambilia (choice E) should top the list of potential causes of diarrhea in this patient. Giardia lambilia has an incubation period of
1-2 weeks or
longer and thus, our patient who returned from Latin America two weeks ago could have contracted the infection any time during his stay there. Furthermore, the clinical picture is also suggestive of Giardia infection, which starts with
watery diarrhea, abdominal pain, loss of appetite and flatulence due to malabsorption of sugars, which frequently accompanies
Giardia infection.
⚠ Aeromonas enteritis (choice A) is a rather unlikely cause of diarrhea in this patient. Although, this organism may present with watery diarrhea and abdominal cramps, fever usually accompanies diarrhea caused by this organism. In addition, the incubation period of this microorganism is between 24 to 48 hours and thus, infection by this microorganism is unlikely to explain traveller’s diarrhea in this patient, who returned from Latin America 2 weeks ago.
⚠ Cryptosporidium (choice B) may present with a clinical picture similar to that of Giardia lambilia and like Giardia it has an incubation period of 1 to 2 weeks. However, Cryptosporidium is a less common cause of traveller’s diarrhea than Giardia lambilia.
⚠ Despite being the most common cause of traveller’s diarrhea, Enterotoxigenic E. coli (choice C) is an unlikely cause of traveller’s diarrhea in this patient. The incubation period of this organism ranges between 1 to 3 days and so, it cannot be the cause of traveller’s diarrhea in our patient who returned from his trip 2 weeks ago.
⚠ Enterohemorrhagic E coli (choice D) is a rather unlikely cause of traveller’s diarrhea in this patient. This microorganism causes inflammatory diarrhea with bloody stool and fever. Also, the median incubation period for microorganism is about 4 days; diarrhea caused by this organism is expected to develop during his stay in Latin America or shortly after arrival to home country.
🔖 Key point:
Diarrhea caused by microorganisms with short incubation periods is more likely to develop during stay or shortly after return to home country. When diarrhea develops weeks after travel, it is either traveller’s diarrhea caused by organisms with long incubation periods like Giardia lambilia or Entamoeba histolytica or non-traveller’s diarrhea due to locally acquired infectious agents or non-infectious disease.