1.Epidemiology of scrub typhus and influencing factors in Yunnan province, 2006-2013.
Y SUN ; C SHI ; X L LI ; L Q FANG ; W C CAO
Chinese Journal of Epidemiology 2018;39(1):54-57
Objective: To understand the epidemiological characteristics of scrub typhus and influencing factors in Yunnan province, and provide further information for the prevention and control of scrub typhus. Methods: Based on the incidence data of scrub typhus reported in Yunnan from 2006 to 2013, the epidemiological characteristics of scrub typhus were analyzed and related environmental factors were identified with panel negative binomial regression model. Results: A total of 8 980 scrub typhus cases were reported during 2006-2013 in Yunnan. The average annual incidence was 2.46/100 000, with an uptrend observed. Natural focus expansion was found, affecting 71.3% of the counties in 2013. The epidemic mainly occurred in summer and autumn with the incidence peak during July-October. The annual incidence was higher in females than in males. More cases occurred in children and farmers, the proportions of cases in farmers and pre-school aged children showed an obvious increase. Panel negative binomial regression model indicated that the transmission risk of scrub typhus was positive associated with monthly temperature and monthly relative humidity. Furthermore, an "U" pattern between the risk and the increased coverage of cropland and grassland as well as an "inverted-U" pattern between the risk and increased coverage of shrub were observed. Conclusion: It is necessary to strengthen the scrub typhus surveillance in warm and moist areas as well as the areas with high coverage of cropland and grassland in Yunnan, and the health education in children and farmers who are at high risk.
Child
;
China/epidemiology*
;
Environment
;
Epidemics
;
Farmers
;
Female
;
Humans
;
Incidence
;
Male
;
Models, Statistical
;
Orientia tsutsugamushi
;
Risk Factors
;
Scrub Typhus/transmission*
;
Temperature
2.Monthly Occurrence of Vectors and Reservoir Rodents of Scrub Typhus in an Endemic Area of Jeollanam-do, Korea.
Seung Hyun LEE ; Young Sun LEE ; In Yong LEE ; Jae Won LIM ; Hee Kwan SHIN ; Jae Ran YU ; Seobo SIM
The Korean Journal of Parasitology 2012;50(4):327-331
Monthly surveys were conducted to investigate the occurrence of chigger mites and seroprevalence of scrub typhus among small mammals in Jeollanam-do, the southwestern part of Korea, from November 2006 through October 2007. Fifty-eight small mammals, including 57 Apodemus agrarius (98.3%) and 1 Crocidura lasiura (1.7%), were captured, and a total of 4,675 chigger mites representing 4 genera and 8 species were collected from them. The chigger infestation rate among small mammals was 69.0%. The most predominant species in A. agrarius was Leptotrombidium scutellare (54.0%), followed by Leptotrombidium pallidum (39.4%), Leptotrombidium orientale (4.4%), Leptotrombidium palpale (1.1%), Neotrombicula tamiyai (0.6%), Eushoengastia koreaensis (0.3%), Neotrombicula gardellai (0.3%), and Cheladonta ikaoensis (<0.1%). The chigger index of A. agrarius was the highest in October (740.0), followed by November (242.0), September (134.6), March (98.3), February (38.2), January (35.3), December (34.5), April (30.8), and May (1.7). The average antibody positive rate of scrub typhus in wild rodents was 50.0%. The seropositive rates were high in October (100.0%) and November (83.3%), whereas those in other months were relatively low (28.6-57.1%). The chigger index of L. scutellare rapidly increased in September to form an acuminate peak in October, followed by a gradual decline. These results suggest that the outbreak of scrub typhus in the southwestern part of Korean peninsula is mostly due to L. scutellare.
Animals
;
Antibodies, Bacterial/blood
;
Antibody Specificity
;
Arachnid Vectors/*microbiology
;
*Disease Reservoirs
;
Humans
;
Murinae/parasitology
;
Orientia tsutsugamushi/*immunology
;
Population Dynamics
;
Public Health Surveillance
;
Republic of Korea/epidemiology
;
Rodent Diseases/parasitology/transmission
;
Scrub Typhus/epidemiology/*transmission
;
Seasons
;
Seroepidemiologic Studies
;
Shrews/parasitology
;
Species Specificity
;
Trombiculiasis/parasitology/veterinary
;
Trombiculidae/*microbiology