Significance of Nitric Oxide Level in Giardiasis.

BACKGROUND: Giardiasis is one of the most prevalent intestinal protozoa infections in humans. Nowadays, nitric oxide (NO) is known to be involved in the immune system against Giardia intestinalis. Therefore, the aim of the present study was to evaluate the level of NO in individuals with giardiasis in comparison to normal subjects.

METHODS: This descriptive study was conducted among 49 Giadia positive and 39 age and gender matched healthy volunteers. Examination of stool samples was done by wet mount technique and formol-ether concentration method. Serum samples were obtained for laboratory examination. NO production was quantified by measuring nitrite, a stable end product of NO, using the Griess reaction based on ELISA method. By using the standard curve in Excel program, the concentration of NO2- in samples was obtained. Finally, all data were analyzed using SPSS version 17.

RESULTS: Values obtained from NO assays were placed into 4 groups: ≤ 10 (decline), 10.01 - 15 (normal), 15.01 - 25 (increase), and more than 25 µM (sharp increase). The mean level of NO in patients with G. intestinalis was 32.19 ± 2.15 µM and in people without G. intestinalis was 17.1 ± 1.33 µM. Eight point two percent of patients with Giardiasis were in normal range, but 2%, 20.4%, and 69.4% were in decline, increase, and sharp increase ranges, respectively. In group 2 (without infection), 17.9% were in normal range, and 20.5%, 51.3%, and 10.3% were in decline, increase, and sharp increase ranges, respectively. There was a statistical difference in nitric oxide levels between positive and negative groups with a 95% confidence interval. (p-value = 0.001).

CONCLUSIONS: In our study, the number of people who showed a sharp increase in NO levels was significantly higher in individuals with giardiasis as compared to the control group, and patients infected with giardiasis showed significant increase in NO levels. Therefore, we suggest that further studies are required to understand the exact function of NO in the immune system against giardiasis in humans. It will be important to offer a new therapeutic target for eliminating G. intestinalis.