Diamanus Montanus Research Articles

Use of DNA hybridizations probes for detection of the plague bacillus (Yersinia pestis) in fleas (Siphonaptera: Pulicidae and Ceratophyllidae).

The detection of active plaque in nature relies primarily on demonstration of the etiologic agent of the disease. Yersinia pestis, in the flea vectors and susceptible mammalian hosts. A live animal assay is currently used for identification of a Y. pestis virulence antigen that is not expressed in the flea. We have found that DNA hybridization probes specific for Y. pestis, used in very simple sample preparation schemes, allow detection of Y. pestis in three species of fleas as well as tissues of experimentally infected mice at minimum concentrations of 1 x 10(6) bacilli/ml. We detected Y. pestis in 22 of 90 (24%) experimentally infected Xenopsylla cheopis (Rothschild), 13 of 25 (52%) Thrassis bacchi (Rothschild), and 9 of 25 (36%) Diamanus montanus (Baker), but no hybridization signals were observed from fleas that had fed on normal mice. The probe technique indicated infection in 9 of 10 potentially infected liver and spleen samples and none of the 5 control samples. Our techniques permit definitive diagnosis in 48 h.

Symbiosis between educational and clinical goals.

Abstract “Vasectomy and Health: Results From a Large Cohort Study,” FRANK J. MASSEY, Jr. et al. In this historical cohort study we identified, located, and, if living, interviewed 10,590 vasectomized men from four cities, along with a paired neighborhood control for each. The times between procedure data and interview or death ranged from under one to 41 years, with median equal to 7.9 years and with 2,318 pairs having ten or more years of follow-up. Participant reports of diseases or conditions that might possibly be related to vasectomy through an immunopathological mechanism were validated by direct contact with physicians and review of medical records. Results of this study do not support the suggestions of immunopathological consequences of vasectomy within the period of follow-up. Except for epididymitis-orchitis, the incidence of diseases for vasectomized men was similar or lower than for their paired controls. (Journal of the American Medical Association 1984;252:1023–9.) “Human Bubonic Plague Transmitted by a Domestic Cat Scratch,” BRUCE G. WENIGER, et al. Bubonic plague was transmitted to a 10-year-old girl in Oregon by a scratch wound inflicted by a domestic cat. The cat probably was infected by contact with infected wild rodents or their fleas. Yersinia pestis was identified in Diamanus montanus fleas collected from an abandoned burrow near the patient's home. Domestic cats may infect humans with Y pestis by inoculation from a scratch. (Journal of the American Medical Association 1984;251:927–8.)

Human Bubonic Plague Transmitted by a Domestic Cat Scratch

Bubonic plague was transmitted to a 10-year-old girl in Oregon by a scratch wound inflicted by a domestic cat. The cat probably was infected by contact with infected wild rodents or their fleas. Yersinia pestis was identified in Diamanus montanus fleas collected from an abandoned burrow near the patient's home. Domestic cats may infect humans with Y pestis by inoculation from a scratch.

Ectoparasites in Two Diverse Habitats in Western Oregon III. Interrelationship of fleas (Siphonaptera) and their hosts1

The host range and distribution of fleas of small mammals were studied in 2 forested habitats of western Oregon, USA: a climax spruce-hemlock forest in Neptune State Park (NSA) and a mixed 2nd growth of small mammals were infested by 14 species of fleas in the NSA, while 14 species of fleas infested 13 mammal species in the FSA. Opisodasys k. keeni was the most common flea collected in the NSA, followed in decreasing order of abundance by Opisodasys vesperalis, monopsyllus ciliatus protinus, Diamanus montanus , and Malaraeus telchinum . Other species regularly found were Atyphloceras m. multidentatus, Catallagia sculleni, Corypsylla ornata, Epitedia scapani, Hystrichopsylla occidentalis , and Megabothris abantis . In the FSA, Orchopeas sexdentatus cascadensis was the most common species collected, while O. Kenni, Pulex irritans, Monopsyllus wagneri , and M. telchinum also occurred (listed in decreasing order of abundance). Atyphloceras m. multidentatus, Catallagia sculleni, Corrodopsylla curvata, Corypsylla jordani, C. ornata and Rhadinopsylla sectilis goodi were uncommon.

Tests of repellents against Diamanus montanus (Siphonaptera: Ceratophyllidae).

Oil of sassafras, oil of pennyroyal, diethyltoluamide (deet) and ethyl hexanediol were tested on white mice as repellents against the flea Diamanus montanus in a parallel-line bioassay study. Relative potencies of the test repellents against Diamanus montanus were 3.59, 1.26, 1.00 and 0.27, respectively. Concentrations of 0.14, 0.41, 0.51 and 1.91% were required to provide 95% protection. Commercial products containing diethyltoluamide and ethyl hexanediol are currently available for use by public health workers, researchers and others who may come into contact with Diamanus montanus .

Field studies of reservoirs and vectors of sylvatic plague at Fort Hunter Liggett, California.

Vectors and reservoirs of sylvatic plague were studied at Fort Hunter Liggett, Monterey County, California, from November 1974 to September 1976, with particular reference to the California Ground Squirrel, Spennophilus beecheyi . The ground squirrel occurred in large numbers on the post, in association with other known reservoirs and intermediaries of sylvatic plague. Ground squirrel fleas ( Diamanus montanus and Hoplopsyllus anomalus ) were collected from 6 rodent and lagomorph species. Casual species of fleas from the ground squirrel included Malareus telchinum (normally found on Peromyscus and Microtus ) and the nonspecific species Echidnophaga gallinacea and Pulex simulans .

Rearing of Diamanus Montanus (Siphonaptera: Ceratophyllidae) and Hoplopsyllus Anomalus (Siphonaptera: Pulicidae)1

Diamanus montanus and Hoplopsyllus anomalus were reared in plastic jars on a substrate of ground corncobs, using suckling mice as the blood meal source and a mixture of guinea pig diet and blood meal as the larval food. D. montanus was reared at 27°C and 80% RH; H. anomalus was reared at 19°C and 25% RH. Under these conditions, cultures of D. montanus produced a monthly surplus of approximately 150 fleas per jar.

Psyllotylenchus viviparus, n. gen., n. sp. (Nematodea: Tylenchida: Allantonematidae) parasitizing fleas (Siphonaptera) in California.

Psyllotylenchus vivriparus , n. gen., n. sp. (Nematodea: Tylenchida: Allantonematidae) parasitizes the fleas Catallagia sculleni rutherfordi Augustson, Monopsyllus wagneri (Baker), Monopsyllus ciliatus protinus (Jordan) and Diamanus montanus (Baker) in California. Psyllotylenchus has an alternation of gamogenetic and parthenogenetic parasitic cycles similar to Heterotylenchus , but differs from that genus in possessing ovoviviparous gamogenetic females which curve with the ventral surface outward when relaxed with gentle heat. Parthenogenetic females also possess a distinct spherical preuteral gland, Heterotylenchus pawlowskyi Kurochkin, 1960 is transferred to the genus Psyllotylenchus .

Plague vector studies. 3. The rate deparasitized ground squirrels are reinfested with fleas under field conditions.

A total of 48,996 fleas was collected from 143 ground squirrels. The fleas were in 3 species, Echidnophaga gallinacea, Hoplopsyllus anomalus and Diamanus montanus. When returned to their habitat, most deparasitized animals recovered their normal complement of fleas on or before the third day; and, in most instances, the flea population on the formerly deparasitized squirrels exceeded the normal complement of fleas from the third to the seventh day. Electrical fences were used to confine the ground squirrels.

Plague vector studies. IV. A comparison of insecticide application techniques for flea control on ground squirrels.

An evaluation of the long term residual life of Dieldrin based on the flea index indicated that from the second month through the twelfth month post-treatment the flea index was less than 0.4 fleas per squirrel in 3 of the treated fields, while the control index ranged from 60.5 to 419.5 fleas per host. From the third to the sixth day post-treatment the flea mortality was higher in study areas treated by direct burrow application of Dieldrin (96.3% and 98.0%) than in those study areas where application was by the surface or area method (92.6% and 95.8%). Burrow treatment resulted in a more rapid knockdown of fleas than did surface treatment. These data are based on 89,028 fleas collected from 1423 California Ground Squirrels; the 3 species present of fleas were Diamanus montanus, Hoplopsyllus anomalus , and Echidnophaga gallinacea.

Plague vector studies. II. The role of climatic factors in determining seasonal fluctuations of flea species associated with the California ground squirrel.

Studies were conducted on California ground squirrels confined in O.4-ha electrically-fenced fields to determine the effects of physical factors in the environment on seasonal fluctuations in the population densities of Hoplopsyllus anomalus, Diamanus montanus and Echidnophaga gallinacea. The summer-breeding species, H. anomalus and E. gallinacea, were greatly restricted in their reproductive activities in the experimental field where moisture was supplemented to keep the soil moist to 1 m in depth; the winter-breeding species, D. montanus, was much more reproductively active during the summer in the experimental area where the soil was kept moist. A total of 46,962 fleas was collected from 468 ground squirrels during the course of this study. Trained ferrets were used to pull electrical cables into the ground squirrel burrows to enable the operators to record the relative humidities and temperatures existing at various levels in the burrow systems.

Plague vector studies. I. The rate of transfer of fleas among Citellus, Rattus and Sylvilagus under field conditions in southern California.

The extent of transfer of fleas among Citellus, Rattus and Sylvilagus was studied. Electrical fences were used to confine the mammals in O.4-ha fields. Based on analysis of 92,694 fleas from 620 hosts, it is concluded that Xenopsylla cheopis, Diamanus montanus, and Hoplopsyllus anomalus will attack atypical hosts, in the same habitat as their usual hosts, at epizootiologically significant rates. An X. cheopis index of 1 occurred on ground squirrels (Citellus beecheyi), and of 0.9 on rabbits (Sylvilagus audubonii).

Control of plague vectors on diurnal rodents in the Sierra Nevada of California by use of insecticide bait-boxes.

Trials were conducted in the Sierra Nevada Mountains of California to test the effectiveness of 10% DDT dust in insecticide bait-box stations against the fleas of native diurnal rodents. The principle host species involved were the chipmunks Eutamias amoenus and E. speciosus, and the golden-mantled ground squirrel, Citellus lateralis. The important flea species were Monopsyllus eumolpi and M. ciliatus on chipmunks, and Diamanus montanus and Oropsylla idahoensis on ground squirrels. When baited daily for 12 days and furnished with 50 g. of 10% DDT dust, the bait-box stations reduced fleas strikingly within 24 hr., but very little residual control was obtained. A second application in which boxes were baited only twice weekly but for 28 days, also resulted in rapid knockdown and a residual control still effective 42 days after removal of the bait-boxes. The effect of the DDT was apparent at a distance of 400 ft. from the nearest bait-box due to the relatively extensive home ranges of the hosts. Although, in these trials, bait-box stations were spaced 100 ft. apart, 200 ft. spacing probably would be as effective with these hosts.

Sylvatic plague studies. X. Survival of rodent fleas in the laboratory.

The longevity of laboratory-reared fleas, two species parasitic on domestic rats and six species parasitic on wild rodents of the sylvatic plague reservoir, was studied. The 10,795 adult fleas used in these studies were maintained at different temperatures and humidities within a range encountered in their natural habitats. Different conditions of host availability were simulated by feeding some adult fleas only once, at the beginning of an experiment, by feeding others daily, and by not feeding others at all.Generally, a single blood meal exerted a beneficial effect on the fleas in that those fed before starvation survived a little longer than those that were never fed.With the exception of Opisodasys nesiotus, all fleas were potentially long-lived under some of the laboratory conditions. The longest-lived fleas in all instances were those kept at high humidities (90% relative humidity or more) and fed daily. An O. nesiotus male survived for 48 days, the longest period of any of this species. The maximum longevity for each of the other species was among females and was as follows: Xenopsylla cheopis, over 5 months; Malaraeus telchinum, over 6 months; Nosopsyllus fasciatus, over 9 months; Orchopeas sexdentatus sexdentatus, 10½ months; Diamanus montanus, over 11 months; Oropsylla idahoensis, nearly 12 months; Megahothris abantis, nearly 16 months.

Sylvatic Plague Studies. VIII. Notes on the Alimentary and Reproductive Tracts of Fleas, Made during Experimental Studies of Plague

Much of the relatively simple internal anatomy of fleas is readily visible, particularly in lightly sclerotized species such as Xenopsylla cheopis (Rothschild, 1903), with the aid of a compound microscope using transmitted light and a lowpower (x 10) objective. The alimentary canal of fleas and the digestion of blood nmeals have been described in detail by Faasch (1935). In plague transmission experiments, progressive formation of plugs of plague organisms in the ventriculus and proventriculus of fleas has been photographed and studied (Eskey and Haas, 1940). The fleas were placed in a drop of water on a microscope slide before covering it with a cover slip. Peristaltic action of the ventriculus was temporarily interrupted by the immersion which stopped movement of the developing bacterial plugs sufficiently to allow the making of photomicrographs. In another study, fleas were retained on a slide without water through the gentle application of pressure on the restraining cover slip by one of the observer's fingers (Burroughs, 1947). The observations reported herein were made using Burroughs' technique and are part of experimental plague transmission studies described elsewhere (Holdenried, 1952). In particularly lightly sclerotized specimens, careful observation revealed even the heart beat in the dorsal portion of the abdomen. The pumping action of the pharyngeal pump, eggs in various stages of development, salivary glands, fat bodies, malpighian tubules, tracheae, muscles and other structures were also observed. Three species of fleas, Diamanus montanus (Baker, 1895), Polygenis gwyni (Fox, 1914) and X. cheopis, were observed during plague transmission studies at the Hooper Foundation.

Sylvatic plague studies. The vector efficiency of nine species of fleas compared with Xenopsylla cheopis

All fleas used in this study were collected in the field and except for Pulex irritans were cultured in the laboratory. The ten species studied were Xenopsylla cheopis, Nosopsyllus fasciatus, Orchopeas sexdentatus sexdentatus, Opisodasys-nesiotus, Megabothris abantis, Malaraeus telchinum, Diamanus montanus, Echidnophaga gallinacea, Pulex irritans and Oropsylla idahoensis.All fleas transmitted in individual feeding studies with the exception of the latter two species, which transmitted en masse. Echidnophaga gallinacea could not be fed periodically as were the other fleas because of its tick-like feeding habits. Consequently, the vector efficiency obtained for this species is not strictly comparable to that found for the other species.The transmission data obtained from individual flea feeding studies was analysed statistically to estimate the expected number of transmissions per flea of each species. These values are obtained as intervals which have a 90% probability of containing the true value. The true vector efficiency of Xenopsylla cheopis was found to be 0·660 ± 0·234 (expected transmissions per flea), that of Nosopsyllus fasciatus to be 0·213 ± 0·157, and that of Orchopeas sexdentatus sexdentatus to be 0·170 ± 0·138. Opisodasys nesiotus, Megabothris abantis, Malaraeus telchinum and Diamanus montanus transmitted very inefficiently.Experimental evidence was obtained that different strains of a species of flea may differ markedly in their biological vector capacity. In contrast to results obtained in this study, Wheeler & Douglas found Diamanus montanus to be an exceptionally good vector; in their studies it proved to be an even more efficient vector than Xenopsylla cheopis. The strain of Diamanus montanus employed by them came from an area widely separated from that in which the strain used in the present studies was originally collected.Since many blocked fleas did not transmit it is probable that the experimentally determined vector efficiencies are lower than they would be in nature, where the blocked flea has constant access to a host and hence greater opportunity to feed.Attempts to determine the number of organisms regurgitated by a blocked flea during its attempt to feed did not prove entirely satisfactory, but gave an indication that the number may be at times from 11,000 to 24,000 organisms. The technique consisted of feeding a blocked flea on the shaved abdomen of a mouse (later on the ear), then immediately doing a biopsy on the area around and including the bite wound. This biopsy material was then finely ground and plated on a sensitive bacteriological medium. Some mice upon which biopsies were performed nevertheless contracted plague and died. This must lead to the conclusion that an infective flea may deposit organisms directly into the capillaries and that the primary stage of infection resulting from a flea bite is frequently bacteraemia.

Tularemia: Attempted Transmission by Each of Two Species of Fleas: Xenopsylla cheopis (Roths.) and Diamanus montanus (Baker)

Tularemia: Attempted Transmission by Each of Two Species of Fleas: Xenopsylla cheopis (Roths.) and Diamanus montanus (Baker)