Introduction
Salmonella paratyphi A emerged in the Indian subcontinent at the end of the 1990s. In Nepal it represents more than one-third of positive blood cultures in enteric fever. We report a cluster of 3 cases after a trek in Nepal. Two more cases returning from Nepal were reported to the national reference center (CNR) for Salmonella in the same year, compared with less than 1 case per year usually.
Methods
Three cases appeared in a group of 7 people after trekking in Nepal during monsoon season. As the people were living in different areas in France, the first author, who was also the mountain leader during the trek in Nepal, contacted the CNR to mention the cluster and began an epidemiologic investigation to try to identify the source of contamination.
Results
The first case was a teenager hospitalized with signs of enteric fever. Three blood cultures were positive for S paratyphi A, and she was treated by ceftriaxone. The 2 other cases were adults. They presented with the same signs and symptoms soon after and were treated as outpatients with azithromycin before blood culture results, as resistance to nalidixic acid was known from the first case. All of the patients were vaccinated against typhoid before travel by Vi vaccine (the only vaccine available in France). Epidemiologic investigation retained 2 possible sources of contamination, but the more probable was a specific place in Kathmandu Valley after the trek. Among the 5 cases returning from Nepal, the CNR could analyze 4 strains: They were susceptible to ampicillin, chloramphenicol, cotrimoxazole, and azithromycin, but resistant to nalidixic acid with decreased susceptibility to ciprofloxacin. All had unique DNA restriction profiles on pulsed-field gel electrophoresis.
Conclusion
Emergence of S paratyphi A in Nepal presents 3 problems for travelers: potentially severe infection, increasing resistance to antibiotics, and lack of an efficient vaccine. Prevention is mainly based on universal hygiene recommendations.