DNA motifs at several informative loci in more than 500 strains of Helicobacter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deletion, insertion, and substitution motifs were found at the right end of the H. pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. residents; type II predominated among Japanese and Chinese; and type III predominated in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Peruvians were also more like those from Spaniards than those from Asians. These indications of relatedness of Latin American and Spanish strains, despite the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World by European conquerors and colonists about 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in people quite recently in human evolution.Helicobacter pylori is a microaerophilic bacterium with the extraordinary ability to establish infections in human stomachs that can last for years or decades, despite immune and inflammatory responses and normal turnover of the gastric epithelium and overlying mucin layer in which it resides. It is carried by more than half of all people worldwide and has attracted great attention as a major cause of peptic ulcer disease and an early risk factor for gastric cancer, one of the most frequently lethal of malignancies worldwide (for reviews see references 23, 48, and 60).

No abstract

No abstract

No abstract

An episode of diarrhea causes weight loss and a temporary cessation of growth in infants and children. Diarrhea is accompained by malabsorption of sugars, nitrogen, fats, and micronutrients. The mechanisms by which acute diarrheal disease produce malabsorption have not been studied carefully. The nutritional costs of malabsorption may pose a major threat if diarrhea becomes chronic or recurrent. The hydrogen breath test for carbohydrate malabsorption does not require intubation or blood drawing and can be used in children to help clarify the importance of carbohydrate intolerance in the duration and perpetuation of acute diarrhea and intestinal bacterial overgrowth.