The Incidence of Leptospires Infection in Reported and Unreported Areas of Leptospirosis Case in Buri Rum Province - อัตราการติดเชื้อเลปโตสไปราของประชากรที่อาศัยในพื้นที่จังหวัดบุรีรัมย์ ที่มีและไม่มีรายงานผู้ป่วย

Abstract

               This prospective research was aimed to determine the incidence of Leptospira infection, prevalence of leptospirosis in the past year and serovar of pathogen compared between reported and non-reported areas of leptospirosis in the past three consecutive years (2000-2002) in Buri Rum Province. Samples were 110 and 116 males aged 15-65 years old in those areas, respectively, who voluntarily participated through the year 2003 - 2004. Data were obtained by interviewing and paired blood testing for IgM and IgG using Indirect Immunofluorescent Antibody (IFA) and serovar identifying by Microscopic Agglutination test. Data were analyzed using rate, ratio, proportion, relative risk (RR) and 95% confidence interval for RR.

                 Results regarding the first blood test showed that incidence of Leptospira infection in the reported areas was 3.52 times greater than that of non-reported areas (RR.=3.52) but such risk was likely to occur by chance (95% CI.=0.99-12.44). Regarding the second blood test, the annual incidence of reported areas decreased to 6.36 percent while the incidence in the non-reported areas remained constant. The first blood test indicated that the prevalence of Leptospirosis in the reported areas was 11.82 percent and different statistically from the prevalence found in the non-reported areas (2.58 percent). The prevalence reported by the second blood test in the reported and the non-reported areas were 9.09 and 2.58 percent, respectively. Both IgM and IgG titer ranged between 1:100 and 1:200. Among the IgM positive people related to the first blood test, 40 percent of them remained positive. Yet all of the IgG positive people, remained so. Serovar found in this research was L.bratislava and there was apparently no fever or any illness among people whose positive IgM and IgG in the second blood test were reported. The findings indicate that these areas are infected with Leptospires without any severe symptom and sign.