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Typhoid fever is the most common clinical diagnosis among febrile patients presenting to hospital in Katmandu. Salmonella enterica serovar Typhi (S. enterica serovar Typhi) and Salmonella enterica serovar Paratyphi A (S. enterica serovar Paratyphi A) with decreased susceptibility to fluoroquinolones and resistance to nalidixic acid are common in recent years. In the present study, we examined the in vitro susceptibility to fluoroquinolones and the presence of gyrA gene mutations in 30 clinical strains of S. Typhi and 39 of S. Paratyphi A, all of which were isolated in Katmandu, Nepal, in 2003. In those strains, we found that 73.3% and 94.9% of S. Typhi and S. Paratyphi A strains contained gyrA gene mutation, and showed the resistance to a quinolone, nalidixic acid, and decreased susceptibility to fluoroquinolones, ciprofloxacin, and levofloxacin. Although fluoroquinolones may still be useful as antibiotics for the treatment of typhoid fever, clinicians should be aware of the possibility of treatment failures of infections with S. Typhi and S. Paratyphi A strains with decreased susceptibility to fluoroquinolones.

A study of diarrheal diseases associated with Cyclospora cayetanensis was conducted in Nepal and Lao PDR. A total of 2083 samples were included in this study. Samples in Nepal were collected from October 1999 to August 2002 whereas samples in Lao PDR were collected from February 2002 to June 2003. C. cayetanensis was detected by direct microscopy using ultraviolet and differential interference contrast microscopy. The overall positive rate in Nepal was 9.2% (128/ 1397). A higher positive rate was observed in children aged 10 years and under (11.1%) and was lowest in the age group of 51-60 years (3.1%). A significantly higher positive rate was observed in the summer (rainy season) (12.6%) with the lowest prevalence in the spring (dry season) (1.8%) (p < 0.05). The positive rate was closely associated with rainfall (ml/month). Interestingly, only one of the total 686 samples (0.1%) from Lao PDR was found to be positive for Cyclospora oocysts.

Cyclospora cayetanensis oocysts in the feces of humans from Kathmandu, Nepal were identified on the basis of their size and other morphological characteristics. We compared the detection of C. cayetanensis oocysts in the feces using three microscopic techniques such as formalin-ether sedimentation, sucrose centrifugal floatation, and direct smear. Standard procedures were used for the formalin-ether sedimentation and the sucrose centrifugal floatation techniques using 0.5 g of feces, however, the direct smear technique was performed using 10 microl of fecal suspension (0.005 g of feces) and observed under the fluorescent microscope. Of the 403 samples examined, 21 samples were positive for oocysts by all three techniques. Therefore, in these 21 samples, the number of oocysts recovered by the three techniques were compared. The highest number of oocyst was obtained by the sucrose centrifugal floatation technique. In contrast, the formalin-ether sedimentation technique was found to be the least reliable concentration technique for the detection of Cyclospora in human feces. Surprisingly, the direct smear technique was found to be an effective and rapid technique for diagnosis of C. cayetanensis making it a technique of choice for routine epidemiological investigation of the prevalence of this infection in human populations.