Monthly Occurrence of Vectors and Reservoir Rodents of Scrub Typhus in an Endemic Area of Jeollanam-do, Korea

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.

Echinostome Infections in the Striped-Field Mouse, Apodemus agrarius, and the Ussuri White-Toothed Shrew, Crocidura lasiura, Caught Near the Demilitarized Zone, Gyeonggi-do (Province), Republic of Korea

A total of 1,498 small mammals (rodents and insectivores), including Apodemus agrarius (n = 1,366), Crocidura lasiura (54), Mus musculus (32), Micronytus fortis (28), Eothenomys regulus (9), Micronys minutes (6), and Cricetulus triton (3), were live-trapped in Gyeonggi-do (Province) (Paju-si, Pocheon-gun, and Yeoncheon-gun) near the demilitarized zone (DMZ) from December 2004 to September 2005. A. agrarius was found to be infected with 3 species of echinostomes (Echinostoma hortense, Echinostoma cinetorchis, and Euparyphium murinum), while C. lasiura was infected with 1 species (Echinochasmus japonicas) of echinostome. Other mammals were free from echinostome infections. Total 16 E. hortense were detected in 7 (0.5%) mice, 9 E. cinetorchis from 5 (0.4%), and 3 E. murinum from 2 (0.1%) out of 1.366 A. agrarius examined. E. japonicus was found only in 1 (1.9%; total 3 specimens) C. lasiura. These results demonstrate that A. agrarius and C. lasiura, inhabiting near the DMZ of Gyeonggi-do serve as the natural definitive hosts for several species of echinostomes, although their infection rates are low. This is the first record of natural infections of A. agrarius with E. cinetorchis and C. lasiura with E. japonicus in the Republic of Korea.

The trematodes and cestodes of Sorex araneus L. in Valaam Island (Ladoga Lake, USSR). 1

The trematode and the cestode fauna was examined in 50 specimens of common shrews Sorex araneus L. (Insectivora: Soricidae) cillected in Valaam Island, URSS during 1988 and 1989. Two species of Trematoda and seven species of Cestoda were identified; prevalence of infection was as follows: Brachulaemus fulvus (86% ), Rubenstrema exasperatum (4% ), Hymenolepis scutigera (54% ), Neoskrjabinolepis schaldybini (26% ), Vigisolepis spinulosa (4% ), Choanotaenia crassiscolex (86% ), Choanotaenia hepatica (6% ), Dilepis undula (2% ) and Polycercus sp. (2% )

Chigger mite infestation of small mammals in a feral biotope of a public park area of south Delhi.

Examination of Bandicota bengalensis (8) and Suncus murinus (4) trapped in a feral biotope of a public park area of south Delhi revealed presence of the known scrub typhus vector Leptotrombidium (L.) deliense, the suspected vector Gahrliepia (S.) ligula and Gahrliepia (Walchia) sp. of chigger mites, on them. The epidemiologically important population indices (chigger infestation rate-CIR and incidence rate--1R) were estimated. The overall CIR of the three mite species on the hosts was 2.83 mite/host, and that of L. deliense on B. bengalensis and S. murinus was 1.62 and 0.25 respectively, whereas that of G. ligula was 0.50 on both the host species. The overall 1R was 66.66 per cent being 62.5 per cent for B. bengalensis and 75.0 per cent for S. murinus. Incidence of L. deliense on B. bengalensis was higher (62.5 per cent) than on S. murinus (25.0 per cent), whereas IR of G. ligula was higher (50.0 per cent) on S. murinus than on B. bengalensis (25.0 per cent). The Chi square test of independence has shown that these chigger species are not host specific, but are rather habitat specific. Chiggers were absent on Mus platythrix from a habitat about 40 meters away from the B. bengalensis and S. murinus collection sites. The high CIR value for scrub typhus vector L. deliense (1.62) warrant investigations on natural infection rates of R. tsutsugamushi in the chiggers and screening of local human population for the infection.

Mesostigmatid mites associated with the house shrew, Suncus murinus, in Rangoon, Burma.

In Rangoon and vicinity Suncus murinus comprises almost 20% of the small mammal population with almost equal load of mesostigmatid mites compared to murine rodents. Suncus murinus was infected by four species of laelapids, out of which L. myonyssognathus seems to infest more on urban S. murinus. The infestation of the free living Androlaelaps or Hypoaspis species is higher on the rural shrews while the Cheyletus species is higher on the urban than the rural S. murinus.