Bandicota Indica Research Articles

Hantaan virus antibody prevalence in rodent populations of several provinces of northeastern Thailand.

We conducted a serological survey of 632 rodents from the northeast region of Thailand in order to assess the presence of Hantaan-like viruses that may be a risk to the human population. Rodents were collected from rice fields, houses and domestic gardens in five northeastern provinces and tested for IgG reacting sera to Hantaan antigen using enzyme-linked immunoassays. The overall prevalence of Hantavirus infection in rodents was 2.1% (13/632). Species that tested positive included Bandicota indica (4.3% positive within species), Rattus exulans (2.1%), R. losea (1.6%) and R. rattus (0.9%). Species such as R. exulans and R. losea are candidate hosts of unidentified Hantaan-like viruses in Thailand.

Reservoir hosts of Leptospira inadai in India.

Isolation of Leptospira from the kidneys of Rattus rattus wroughtoni hinton, Rattus rattus rufescens, Bandicota bengalensis and Bandicota indica was attempted in Bangalore in southern India. In total, 296 spirochaetes were isolated from 1,348 kidney cultures (an isolation rate of 22%). A batch of fifty-six isolates from India was identified, based on serological and polymerase chain reaction analysis, of which twenty-three isolates were identified as L. inadai by the World Health Organization/Food and Agriculture Organization Collaborating Centre for Reference and Research on Leptospirosis, in Brisbane. This is the first record of isolation of L. inadai from rodents. The preponderance of L. inadai in four different species of rodents suggests that these animals could be the natural reservoir hosts of L. inadai, and raises a critical question as to the likely impact of this species of Leptospira on the renal carrier status of other Leptospira pathogenic to humans and animals in this part of India. Virulence studies conducted at the University of Trieste in Italy, revealed that isolates of L. inadai from India were moderately or totally serum resistant when subjected to a serum killing test. To establish the possible seroprevalence of this species in the population, the inclusion of L. inadai in the battery of leptospiral antigens used for sero-epidemiological studies is recommended.

BODY MASS, TESTES MASS, AND SPERM SIZE IN MURINE RODENTS

The relationships among testes mass, sperm size (as indicated by sperm tail length), and body mass of Old World rats and mice were investigated. A near isometric relationship between testes mass and body mass was found but not between body mass and sperm size. In a few lineages, testes mass deviated considerably from the regression line with relatively very small testes occurring in Bunomys fratrorum, Bandicota indica, and B. savilei of Asia, Aethomys ineptus of Africa, some Pseudomys, and all Notomys of Australia. By contrast, relatively large testes mass occurred in Apodemus, Berylmys, and Maxomys bartelsii of Asia, Pogonomys of New Guinea, and some Australasian Rattus, Melomys, and Mastacomys. Considerable variability in sperm size was also evident; some species that had relatively small testes also had relatively small spermatozoa. The reason(s) for interspecific variation in relative testes mass and sperm size is unknown, but the data provide an opportunity to test the hypothesis that differences in relative testes mass, and perhaps sperm size, relate to interspecific differences in the amount of intermale sperm competition and in breeding systems.

Redescription of Leptotrombidium (Leptotrombidium) imphalum (Acari: Trombiculidae), with observations on bionomics and medical importance in northern Thailand.

Leptotrombidium (Leptotrombidium) imphalum Vercammen-Grandjean & Langston is redescribed and illustrated. Specimens were collected from the rodents Rattus rattus, Rattus losea, and Bandicota indica in Chiangrai Province, northern Thailand. The species was found on hosts collected on dikes at the margins of rice fields and in adjacent fruit plantations and along irrigation canals, especially in areas covered with the grasses Imperata cylindrica (lalang grass) and Saccharum arudinaceum. The etiological agent of scrub typhus, Orientia (formerly Rickettsia) tsutsugamushi has been isolated from L. (L.) imphalum, rodent hosts, and patients who live and work in the same habitats.

Interspecific Variation in Structural Organisation of the Spermatozoon in the Asian Bandicoot Rats, Bandicota Species (family Muridae)

AbstractThe structural organisation of the spermatozoon from two species of bandicoot rats Bandicota bengalensis and Bandicota indica was investigated by light and electron microscopy together with the effect of incubation in Triton‐X 100 and sodium dodecyl sulphate. The sperm head of B. bengalensis is invariably falciform, has a uniform electron‐dense nucleus capped by an acrosome with a posteriolateral equatorial segment, a subacrosomal cytoskeleton with a large rostral perforatorium, and a sperm tail, attached to the lower concave surface of the sperm head, with typical coarse fibres and fibrous sheath. By contrast, the sperm head shapes of B. indica are generally conical or bulbous, the nucleus contains a few large vacuoles, the acrosome lacks an equatorial segment, no recognisable perforatorium occurs, and the sperm tail, which is attached basally, is very short with only modest development of coarse fibres and fibrous sheath. These results indicate that, within the genus Bandicota, huge interspecific differences in morphology of the spermatozoon have evolved. The spermatozoa of B. bengalensis are similar to those of Rattus and many other murids and thus presumably represent the ancestral condition, whereas those of B. indica (and B. savilei) are unlike spermatozoa from any other eutherian mammal so far described. © 1998 The Royal Swedish Academy of Sciences. Published by Elsevier Science Ltd. All rights reserved

A new ecology for scrub typhus associated with a focus of antibiotic resistance in rice farmers in Thailand.

Following the documentation of chloramphenicol-resistant and doxycycline-resistant strains of Orientia tsutsugamushi (Hyashi) in northern Thailand, we conducted ecological and epidemiological studies near the houses of patients hospitalized with antibiotic-resistant infections. New associations between chiggers, rodents, and O. tsutsugamushi in active rice agriculture areas, an ecological habitat not described previously, are reported. Rattus rattus (L.) was the most common species (representing 85.8% of the 1,433 rodents processed), followed by Rattus losea (Swinhoe) (9.4%), Bandicota indica (Bechstein) (3.6%), and Rattus argentiventer (Robinson and Kloss) (1.3%). O. tsutsugamushi was isolated from 30% of the R. rattus and R. losea, 29% of the B. indica, and 33% of the R. argentiventer collected. Mean minimum infection rates were 0.03 in Leptotrombidium chiangraiensis Tanskul & Linthicum, a new species of chigger, and 0.002 in Leptotrombidium imphalum (Vercammen-Grandjean & Langston), a chigger species not previously associated with scrub typhus transmission. Efficient vertical and horizontal transmission of O. tsutsugamushi by L. chiangraiensis and L. imphalum was demonstrated. During a 19-mo period from October 1993 to April 1995, the overall prevalence of human IgM and IgG antibody to O. tsutsugamushi was 25.5 and 47.3%, respectively. L. chiangraiensis and L. imphalum are incriminated as vectors of O. tsutsugamushi in a rice field habitat associated with a focus of antibiotic resistance.

Isolation and presumptive serological characterization of hantavirus from wild rat (Bandicota indica)

Isolation and presumptive serological characterization of hantavirus from wild rat (Bandicota indica)

Sarcosporidiasis in rodents from Thailand.

One to six Sarcocystis spp. were identified in the skeletal muscles of 41 (33%) of 124 wild rodents (Rattus spp. and Bandicota indica) mainly captured in the central plains of Thailand throughout the year in 1995. Included were S. singaporensis, S. villivillosi, and S. murinotechis-like cysts all of which showed a striated cyst wall at the light microscopical level, and Sarcocystis cymruensis, S. sulawesiensis, and S. zamani which possessed smooth cyst walls. The ultrastructure of the cyst wall and other morphological characteristics used to distinguish species are described. By inoculation of muscle cysts from wild-caught rodents into coccidia-free pythons (Python reticulatus, P. molurus bivittatus), we confirmed that P. reticulatus is a suitable definitive host for S. singaporensis and S. zamani in Thailand. Furthermore, we showed by fecal examination of reticulated pythons collected in the wild and subsequent experimental infection of laboratory rats that these hosts also are naturally infected with both species. Sarcocystis cymruensis is reported for the first time from Southeast Asia. This parasite was prevalent in brown rats (Rattus norvegicus) and bandicoot rats (B. indica) which were captured near human habitations; it is likely to be transmitted to rats via cats. The definitive hosts of S. sulawesiensis and S. murinotechis are unknown. Hence, at least three Sarcocystis spp. (S. singaporensis, S. zamani, S. villivillosi) are likely to cycle between snakes and rodents in agricultural areas in Thailand. Among these, S. singaporensis appears to be the most prevalent species.

A new species of Leptotrombidium (Acari:Trombiculidae) collected in active rice fields in northern Thailand.

Leptotrombidium (Leptotrombidium) chiangraiensis Tanskul & Linthicum is described and illustrated as new from specimens collected from the rodents Rattus rattus (L., 1758), Rattus argentiventer (Robinson & Kloss, 1916), Rattus losea (Swinhoe, 1870), and Bandicota indica (Bechstein, 1800) in Chiangrai Province northern Thailand. The new species was collected in active rice fields and adjacent fruit plantation areas. The etiological agent of scrub typhus, Orientia (formerly Rickettsia) tsutsugamushi (Hayashi), has been isolated from patients who live and work in the same habitat where L. chiangraiensis is the predominant Leptotrombidium species.

Seroepidemiology of Hantaan virus infection in Taiwan.

In order to investigate the infection rate of Hantaan virus in Taiwan, a total of 6,536 human serum samples were collected from residents, selected by stratified random sampling, from 19 townships covering four different ethnic groups: Aborigines, Fukien Taiwanese, Hakka Taiwanese, and Mainland Chinese. Serum samples were screened for Hantaan virus antibodies by indirect immunofluorescence. The prototype Hantaan virus (76/118)-infected Vero E6 cells were used as the viral antigen for the antibody detection. Among 6,536 human serum samples, 403 (6.2%) samples had Hantaan virus antibodies. The seropositive rates for males and females were 6.1% and 6.2%, respectively. A higher seropositive rate was found among Aborigines on the Orchid Islets (11.5%) and Fukien Taiwanese on the Penghu Islets (11.6%), while the lowest rate was observed among Hakka Taiwanese in the south of Taiwan (2.5%). In comparing with different ethnic groups, the highest prevalence was found among Fukien Taiwanese (8.1%) and the lowest among Mainland Chinese (4.9%). Among the different geographical areas, the highest positive rate was found in western Taiwan (7.1%) and the lowest in southern Taiwan (5.4%). Hantaan virus antibodies were also detected in 22 of 548 (4.0%) rat serum samples. The highest seropositive rate was found in rat sera collected from the Orchid Islets (21.4%). None of the rat sera collected from Hsinchu, Miaoli, Changhua, Nantu, Yunlin, Chiayi, Tainan, and Penghu Counties were positive. Hantaan virus antibodies were found in rats: Rattus rattus (20%), Bandicota indica (9.0%), Rattus norvegicus (8.3%), Bandicota nemorivaga (6.3%), Rattus losea (4.2%), and Apodemus agrarius (1.6%). Hantaan virus antibodies were not detected in rat sera collected from species of Rattus coxinga, Rattus culturatus, Mus musculus, Mus caroli, Suncus murinus, and Apodemus semotus. The results show that the Hantaan or Hantaan-related virus exists and is distributed widely in both human and rats in Taiwan.

Serological survey of spotted fever group rickettsia in wild rats in Thailand in the 1970s.

In Thailand, the first human cases of spotted fever group rickettsiosis were reported in 1994, but no serosurveys on wild rats have yet been conducted. We investigated the seroepidemiology in wild rats collected in the 1970s from two regions in Thailand, and found a 62.2% positive rate of antibodies for spotted fever group rickettsia (SFGR) by the indirect immunofluorescence antibody test. Of the antibody-positive rats, 82.2% had higher titers of antibodies against TT-118 than those against Rickettsia japonica, which suggests that Thailand is infested mainly with the TT-118 strain or its antigenically related organisms. The prevalence of antibodies in Bandicota indica was significantly higher than that in other species, which suggests that B. indica is important as a reservoir of SFGR in Thailand.

Habitat relations within lowland grassland rodent communities in Taiwan

Patterns of habitat use by murid rodents were examined in lowland grasslands in Taiwan. Fifteen grassland sites were live‐trapped in 1990, and 16 microhabitat variables were measured at each of 539 trap stations in the sampling sites. Mus caroli, Apodemus agrarius, Rattus losea, and Bandicota indica were captured regularly during the sampling. Rattus norvegicus and Nivivenrer coxingi were captured infrequently. The analysis focused on the four common species. Mus caroli, R. losea, and B. indica have been considered to be commensals of humans and to be largely dependent upon agricultural crops. However, these species were captured in natural habitats, often far from agricultural areas. M. caroli and R. Iosea were by far the most abundant species.Vertical stratification of the habitat did not increase the number of species or overall rodent abundance. Rather, sites with well‐developed grass cover and little vertical development of vegetation above the grass layer had the highest overall densities of rodents.Use of habitat was very similar among the four common species and was concentrated in areas with dense grass cover. Overlap in habitat use was particularly extensive in the core areas of greatest occupancy. Relative population abundances (number of individuals captured per trap station) of the four species were related weakly to the microhabitat variables. These variables were better predictors of capture probabilities of M. caroli and R. losea at individual trap stations, as revealed by multiple logistic regression. Abundances and capture probabilities did not appear to be affected by the presence or abundance of other species.It is suggested that body size differences may facilitate coexistence of these four species of ecologically similar murids. Beginning with the smallest species (M. caroli), body masses of each subsequent species in the series differ by at least a factor of two. These grassland communities may be somewhat resistant to invasion by more similar‐sized species of murids.

Ultrastructure of cardiac myocytes in the greater bandicoot rat (Bandicota indica).

Cardiac myocytes in the left ventricle and atrium of the greater bandicoot rat (Bandicota indica) were examined by transmission electron microscopy. The fine structure showed typical features of mammalian cardiac myocytes. In atrial myocytes, however, the areas occupied by mitochondria were much smaller than that filled with myofibrils. The decrease in mitochondria and the abundance of myofibrils are thought to be an ultrastructural adaptation to the large body size of this species. Many conducting myocytes were observed in both atrium and ventricle. The atrial conducting myocytes were ultrastructurally different from the Purkinje fibers of the ventricle. We suggest that the abundance and the ultrastructural variation of conducting myocytes are related to the physiological aspects, such as body size, of this animal.

The effects of rat damage on deepwater rice yields in Bangladesh

Abstract The effects of rat damage on deepwater rice (DWR) yields were evaluated in 1987 and 1988 by the use of exclusion fences in the Bangladesh Rice Research Institute's DWR site at Rajbari, Gazipur. Bandicota indica (Bechstein) and B. bengalensis (Gray and Hardwicke) started cutting the elongating stems from August and continued until harvest (November). Damage to stems and panicles was much higher in 1987 than 1988. Damage at the elongation stage (47%) was higher than at the ripening stage (34%). Estimated yield losses were 68% in 1987 and 32% in 1988 (average 47%). Management of rats is essential in such highly infested DWR areas. A simple and inexpensive rat control method needs to be developed for the subsistence DWR fanners of Bangladesh.

Grouping of hantaviruses by small (S) genome segment polymerase chain reaction and amplification of viral RNA from wild-caught rats.

A single pair of consensus primers in the polymerase chain reaction (PCR) amplified a conserved region of the small genome segment of twenty hantavirus isolates. Isolates tested included representatives of the four recognized hantaviruses, Hantaan, Seoul, Puumala and Prospect Hill, as well as isolates from Mus musculus (Leakey), Bandicota indica (Thailand 749), and Suncus murinus (Thottapalayam). Viruses from the Nairovirus and Phlebovirus genera yielded negative results. The amplification products were 281-nucleotide pairs (np) in length, with the exception of Thottapalayam, which had an amplification product of approximately 320 np. Products of all isolates were detected by Southern hybridization with a 32P-labeled Hantaan 76-118 amplicon, while an oligonucleotide probe to a conserved region of the amplified fragment failed to detect some isolates of Seoul and Puumala viruses. Restriction endonuclease analysis allowed three groupings: Hantaan-like viruses, Seoul-like viruses, and a diverse group of patterns for the other viruses. Differences were found within the Seoul-like virus group by this method, whereas the Hantaan-like viruses were shown to be similar. RNA extracted from tissues of seropositive and seronegative rats trapped in Baltimore showed the practical application of the test. Hantavirus-specific RNA was detected in 12 (92%) of 13 seropositive rats, but not in seronegative rats. This simple method for detecting and characterizing hantaviruses has potential for epidemiologic studies and for diagnosing human hantavirus infections.

Molecular phylogeny of Rodentia in the descent of genusBandicota

The interrelationships of murids and other rodent families as well as the evolutionary descent of multiple β-globins of murines are deduced from parsimony trees of relevant globin sequences. Our results show that Caviidae arises first, followed by Sciuridae which joins Muridae. In the murid line of descent Spalacinae arises first followed by two branches, one representing Cricentinae and Arvicolinae and the other Murinae. Although the rates of evolution of globin genes in the different rodent families are different, the murid branches show more or less a uniform rate of evolution of β globins. We have used this information to show that mouse-rat divergence occurred around 20 million years ago. The evolutionary rationale for the presence and the expression of different β-globin genes in murid populations is also discussed. Based on mitochondrial DNA restriction fragment analysis, the between-species relationships ofRattus rattus rufescens, Bandicota indica andBandicota bengalensis have been assessed and the time of divergence of the two bandicoot rats estimated.

Nematodes of the Family Heligmonellidae (Trichostrongyloidea) Collected from Rodents of the Ryukyu Archipelago and Taiwan

Six species of the family Heligmonellidae (Nematoda: Trichostrongyloidea), including 3 new species, are recorded from rodents of the subfamily Murinae in the Ryukyu Archipelago and Taiwan. Heligmonoides ikeharai n. sp. from Tokudaia osimensis muenninki on Mt. Yonaha, Okinawa Island, is characterized by extremely long spicules and hypertrophied ridges in the prevulval region. Heligmonoides taiwanensis n. sp. from Apodemus draco on Mt. Alishan, Taiwan, is distinguished from other members of the genus in having a markedly asymmetrical bursa and stout bursal rays. Heligmonoides alishanensis n. sp. from Niviventer confucianus on Mt. Alishan differs from the allied forms in lacking hypertrophied ridges at the level of the middle of the spicules and in having longer spicules and a smaller body. Nippostrongylus sp. from N. confucianus on Mt. Alishan resembles Nippostrongylus brasiliensis but is distinguishable in that the externolateral ray is almost the same length as the lateroventral ray in the left lobe, and the fused tips of the spicules are thin and straight. Heligmonoides ryukyensis from Mus caroli and Orientostrongylus tenorai from Bandicota indica are first recorded from Taiwan. Heligmonellid nematodes parasitic in wild rodents in these areas are considered to have been introduced with their hosts from the mainlands of China and Japan through land connections in the Pleistocene.

Water Requirement Estimated from the Renal Structure and Stomach Contents in Rattus losea and Bandicota indica

Water Requirement Estimated from the Renal Structure and Stomach Contents in Rattus losea and Bandicota indica

Food preference studies of the larger bandicoot rat,Bandicota indica (Bechstein)

The food preferences of the South-Asian commensal rat,Bandicota indica were studied to evolve a suitable bait for control. Amongst cereals clear preference towards rice in its whole/divided form was evident. Amongst additives 7\2-10% groundnut oil enhanced bait intake significantly while 2% salt and sugar did not influence the rat’s diet choice. The results indicate whole/broken rice mixed with 7\2-10% groundnut oil as the most attractive bait for poisoningB. indica.

Supernumerary chromosomes in Bandicota indica nemorivaga and a female individual with XX/XO mosaicism

Supernumerary chromosomes and an XX/XO mosaic individual of B. i. nemorivaga are described. The supernumeraries are small metacentric chromosomes and are stained all along their length in C-band preparations. They have morphology and staining characteristics similar to those observed in different populations of Rattus rattus. Extensive G-band similarity of the chromosomes of B. i. nemorivaga and R. rattus and the size, shape and staining behaviour of the supernumerary chromosomes in these genera suggest that they have acquired supernumeraries from a common ancestor.