Rat Mite Research Articles

Experimental filarial infections in cotton rats

A method for producing semi-quantitative infections of the filarial worm, Litomosoides carinii, is described. Tropical rat mites, Bdellonyssus bacoti, were fed on infected cotton rats, Sigmodon hispidus texianus. Infective larvae were dissected from the mites in half strength Tyrode's solution and transferred in counted numbers to subcutaneous pockets formed by surgical incision in the skin of cotton rats. Intact mites and mites in whose integument a slit had been cut were transferred to subcutaneous pockets, the abdominal cavity and the stomach. Larvae were also transferred to the mouths of cotton rats. The results indicate that larvae cannot escape from intact mites except when these are feeding, and that infection does not occur by way of the mouth or stomach. Larvae migrate from the skin to the pleural cavity within a few days and before they undergo appreciable growth. Most larvae migrate equally promptly from the abdominal cavity although a few remain there and develop normally.

The tropical rat mite (Liponyssus bacoti) as an experimental vector of Coxsackie virus.

Summary and ConclusionsThe tropical rat mite, Liponyssus bacoti, was shown to harbor the Dallas M. B. strain of Coxsackie virus for as long as 16 days following an infective blood meal. Of 36 mice exposed to the bites of infected mites during this period only one mouse, which was bitten on the third day, developed Coxsackie infection. The possibility that this animal was infected by ingesting a mite rather than by being bitten by one cannot be excluded. The fact that other mice bitten on the same or closely adjacent days did not develop infection tends to suggest that such might have been the case. Limited tests with progeny from the infected mites did not indicate that transovarian passage of the virus occurred. Thus it would seem that the mite, Liponyssus bacoti, can play but a small role, if any, in the transmission of the strain of Coxsackie virus tested.

Methods for feeding tropical rat mites on blood and other fluids through a membrane

A method for feeding tropical rat mites through a membrane is described. The thin portions of baby chick skin is the most easily obtainable membrane, but several other fresh animal membranes were equally successful. The mites accepted whole blood from several species of animals equally well and accepted diluted blood and plasma nearly as well as whole blood.

A Humidity Chamber for Maintaining the Tropical Rat Mite, Bdellonyssus bacoti

A Humidity Chamber for Maintaining the Tropical Rat Mite, Bdellonyssus bacoti

Observations on Characters for Identifying the Developmental Stages and for Determining the Sex of Live Tropical Rat Mites

Observations on Characters for Identifying the Developmental Stages and for Determining the Sex of Live Tropical Rat Mites

Experimental transmission of tularemia by the tropical rat mite.

Summary 1. Quantitative methods of study were used in an attempt to observe the changes which took place within infected mites (Bdellonyssus bacoti) after prolonged periods of starvation and after feeding on various types of hosts. 2. The tropical rat mite was shown capable of retaining an infection of Bact. tularense from the protonymph stage throughout the subsequent stages of a single generation. In certain instances this mite transmitted the infection to the next generation. 3. The infection was also retained after several feedings on recovered mice without reduction of the number of infectious organisms. 4. Even after prolonged periods of fasting, no significant decrease in the number of organisms per mite was noted. 5. The tropical rat mite was unable to produce an infection in normal mice by biting. Infection resulted when the mites were crushed orally by the mice. 6. The LD50 titration indicated no loss of virulence in the Sm strain of Bacterium tularense upon mite passage, nor was any increase in virulence noted.

The Mouth Parts of the Adult Female Tropical Rat Mite, Bdellonyssus bacoti (Hirst, 1913) Fonseca, 1941 [= Liponissus bacoti (Hirst)], with Observations on the Feeding Mechanism

The Mouth Parts of the Adult Female Tropical Rat Mite, Bdellonyssus bacoti (Hirst, 1913) Fonseca, 1941 [= Liponissus bacoti (Hirst)], with Observations on the Feeding Mechanism

On the Occurrence of the Tropical Rat Mite,Bdellonyssus Bacoti(Hirst, 1913)—SynonymLiponyssus Bacoti(Hirst)—in Great Britain

On the Occurrence of the Tropical Rat Mite,<i>Bdellonyssus Bacoti</i>(Hirst, 1913)—Synonym<i>Liponyssus Bacoti</i>(Hirst)—in Great Britain

Studies of acari

The present paper is mainly concerned with the records and descriptions of new species of parasitic acari obtained in Ceylon and sent to me during 1947 by Mr Gordon B. Thompson, of whose collection they form a part. The study of the specimens of the tropical rat mite,Echinolaelaps echidninus(Berl.), represented in this material led me to re-examine both the literature and the specimens of this species contained in my own collection, and I have included in the present paper the results of this investigation and have established various forms of the species which this necessitates besides showing the probable relationships existing between them.

The Tropical Rat Mite, Liponyssus Bacoti, as an Experimental Vector of Rickettsialpox 1,2

SummaryPreliminary tests have shown that the tropical rat mite, Liponyssus bacoti, can transmit the agent of rickettsialpox, Rickettsia akari, from mouse to mouse, though present observations do not indicate it to be an efficient vector. In the early tests no attempt was made to prevent test mice from eating the mites, but in one successful transmission to baby mice this could not have occurred. Infection was demonstrated in nymphal progeny, indicating transovarial passage of the agent. The agent was shown to persist in a colony for at least 34 days, and in dead mites for at least short periods.Though the disease is not now known beyond the limits of New York City, the host habits and much more widely known distribution of I. bacoti compared to that of the presently known natural vector, Allodermanyssus sanguineus, suggest the former is of potential importance in planning control measures or in surveying future foci.

An Apparatus for Removing Tropical Rat Mites from Large Quantities of Bedding Materials

For certain experiments involving the use of the tropical rat mite, Liponyssus bacoti, as vector of the cotton rat filaria, Litomosoides carinii, it has been necessery to make rapidly available several thousand adult mites from a single source. A method for producing the required number of mites by raising them on a white rat or a cotton rat in a metal tank containing wood shavings and hay has already been described (Scott, Stembridge, and Sisley, 1947). The apparatus shown in Fig. 1 has been constructed for the purpose of extracting within a single working day this large number of adult mites and the even larger number of accompanying nymphs from approximately 4000 cc of wood shavings and an equal volume of hay. The principal on which the apparatus is based is that used by Bertram (1946) in an apparatus for removing mites from small quantities of sawdust, namely that of driving the mites ahead of a wave of heat. Because of the problem of condensation of moisture the closed system of Bertram was replaced by an open trough of galvanized sheet iron surrounded by a moat containing water. Instead of a hot wire heating element there was substituted an infra red bulb of 250 watts, the back of which is reflector coated. This bulb is mounted on a carriage containing two pulleys which run on a wood track at a sufficient height above the trough to cause the principal heating area to slightly more than cover the width of the trough. The motive power is provided by a small electric motor turning a glass tube. A heavy cotton cord from the lamp carriage is wound twice around this tube, then passed through a pulley and attached to a weight. The length of the cord is adjusted so that the weight will rest on the floor just before the lamp reaches the end of the tank, relieving the tension and allowing the cord to slip. Thus if the operator is absent there will be no damage to the mechanism and any mites remaining at the end of the trough will not be killed by excessive application of heat. The lamp moves at the rate of ? inch per hour and will heat a 1 inch layer of sawdust or a 4-inch layer of loose hay. It was found that by the time mites stranded on the end of a piece of hay were forced to drop off, the metal bottom was so hot that they were killed. The bottom of the trough was therefore lined with a ?-inch sheet of hard asbestos-cement composition board to delay conduction of heat along the bottom. An auxiliary hot wire heater can be hung from the lamp carriage beneath the trough and just behind the center of the lamp so as to heat a thicker layer of sawdust from beneath. When the mites are not too numerous they can be removed from the inner top edge of the trough by means of a suction bottle. One hole of the rubber stopper in this bottle is covered with bolting silk and attached by rubber and glass tubes to a suction pump, while the other hole is provided with a tapered and bent glass tube into which the mites are sucked. Some mites will fall into the water and can be

A Method for Providing a Constant Supply of Tropical Rat Mites, Liponyssus bacoti, Infected with the Cotton Rat Filaria, Litomosoides carinii

Methods for raising and handling tropical rat mites for infection experiments with Litomosoides carinii have been placed on a routine basis as a result of experiments extending over the past year. Our experience agrees with that of several other investigators in indicating that this mite is more difficult to raise in the laboratory during the summer than during our mild winter. We will not be certain that we have overcome all of the seasonal difficulties until after the next summer, but we have hopes that we have done so, since our present methods were developed as a response to the difficulties of the past summer. EQUIPMENT

An Ectoparasitic Survey of Mammals from Lavaca County, Texas

Maxcy (1926) first noted that rats and mice might be the reservoir of endemic typhus, and that fleas, mites, or ticks, were probable transmitters of the disease in the United States. Since that time, many investigators have recovered the rickettsiae of typhus fever from rats and their fleas. Dyar, Rumreich, and Badger (1931) first demonstrated the natural infection of the rat fleas, Xenopsylla cheopis (Rothschild) and Leptopsylla segnis (Schonheer) with endemic typhus. The fleas were taken from rats trapped in Baltimore, Md., and Savannah, Ga. Brigham (1941) reported the recovery of endemic typhus fever rickettsiae from naturally infected chicken fleas. Alicata (1942) obtained experimental transmission of the typhus rickettsiae from rat to rat with the sticktight flea, Echidnophaga gallinacean (Westwood). Dove and Shelmire (1932) reported the laboratory transmission of endemic typhus from guinea pig to guinea pig through the bites of tropical rat mites, Liponyssus bacoti (Hirst). Mooser, Zinsner, and Castaneda, working in Mexico City in 1930, obtained transmission from rat to rat by the rat louse, Polyplax spinulosa (Burmeister).

RAT MITE DERMATITIS

IT IS possible that rat mite dermatitis due to Liponyssus Bacoti Hirst is more frequent than the literature indicates. Bishopp,1Shelmire and Dove2in Texas, Weber3in Chicago and C. R. Anderson4in Los Angeles have reported cases. Because this mite may be the vector of endemic typhus and can become an occupational hazard, recognition of the dermatitis and the mite are important. No report has been made of its occurrence in this part of the United States. REPORT OF CASES A woman employed in an electrical industry noticed some small red marks on her arms, neck, abdomen and legs, associated with pruritus. She discontinued work for one week, and the rash and symptoms disappeared. There was an immediate recurrence of the process as soon as she resumed her occupation. Four other employees were similarly affected at the time. An examination of the working environment

Transmission of Litomosoides carinii to Mice and Hamsters

Litomosoides carinii is a filariid parasite of the cotton rat, Sigmodon hispidus. It has been used extensively in the United States to investigate the chemotherapy of filarial infections. R. W. Williams and H. W. Brown1 and J. A. Scott (private communication) have recently shown that infection was transmitted from one animal to another by means of the tropical rat mite Liponyssus bacoti. These workers kindly showed their results and methods to one of us and provided us with a colony of the mites and some infected cotton rats. Further infected cotton rats were kindly lent us by Prof. R. M. Gordon.

The Laboratory Rearing of the Tropical Rat Mite, Liponyssus bacoti (Hirst)

The Laboratory Rearing of the Tropical Rat Mite, Liponyssus bacoti (Hirst)

The Transmission of Litomosoides Carinii , Filariid Parasite of the Cotton Rat, by the Tropical Rat Mite, Liponyssus bacoti

The Transmission of <i>Litomosoides Carinii</i> , Filariid Parasite of the Cotton Rat, by the Tropical Rat Mite, <i>Liponyssus bacoti</i>

Observations on the Tropical Rat Mite, Liponyssus bacoti, as an Ecto-Parasite of Laboratory Animals and Suggestions for Its Control

The tropical rat mite, Liponyssus bacoti, was originally reported (Hirst, 1913) from the Norway rat, Rattus norvegicus, in Egypt. Bishopp (1923) and Ewing (1923) independently published records of its occurrence in the United States. Since that time the species has been widely reported, and there are records from the Northern United States (Riley and Johannsen, 1938) as well as from the Southern States where it is usually conceded to be most abundant. The mite is an avid blood sucker readily attacking man when an opportunity offers. Much annoyance and irritation, arising from bites of this arthropod, have been experienced by occupants of quarters where a rodent extermination program has been carried out. Hungry mites will travel considerable distances and will willingly substitute man for their normal rat host when the latter has been destroyed. Bishopp (1923) describes the reactions suffered by persons who have been bitten, and attention has recently been redirected to this subject by Anderson (1944) who states that ratmite is frequently overlooked, being diagnosed as scabies or other skin disturbances. Aside from the dermatitis produced by Liponyssus bacoti, there is the grave suspicion that it is a disease carrier. Shelmire and Dove (1931) and Dove and Shelmire (1931, 1932) noted that the distribution of the mite correlated well with the occurrence of endemic or murine typhus, and that rat-mite was coincidental with this disease in Northern and Eastern Texas. They noted further that the feeding habits and biology of these mites could readily be associated with the known course of the disease in rats in such a way that transmission of the typhus from rat to rat could easily take place. Experimental transmission of a laboratory strain of endemic typhus from one laboratory animal to another, through the mites, was also successfully accomplished by these authors. Rats and guinea pigs were employed, and positive evidence of transmission was obtained in eight instances. Furthermore, some evidence was obtained that hereditary transmission through the egg could occur. This evidence should emphasize the need for seriously considering Liponyssus bacoti in the role of a typhus transmitter, and as an agent for maintaining the disease in the rodent commensals of man. Certainly the detailed study of a typhus outbreak can not entirely exclude this arthropod in favor of the flea species as a responsible factor. When an unusually heavy infestation of Liponyssus bacoti was discovered on rats, mice and hamsters in the animal house of the Eighth Service Command Laboratory, Fort Sam Houston, Texas, in April 1945, an excellent opportunity presented itself for making some population studies and limited experiments on methods of control. Since the infested animals were intended for experimental work relative to study of disease, and since mites were literally crawling everywhere, there was no time for extended research. The practical question of immediate control came first; life history and other observations were secondary.

RAT MITE DERMATITIS

Rat mite dermatitis has been reported in the literature only five times, and its occurrence in the United States, but three times. Cases have been reported by Cleland 1 and by Hirst 2 in Australia, by Bishopp 3 and by Shelmire and Dove 4 in Texas and by Weber 5 in Chicago. These isolated reports indicate a rarity of the disease, but the fact of its occurrence in widely separated parts of the world should lead one to expect it wherever the brown rat is found. The disease should be ubiquitous, and I believe the general failure to recognize it is simply because of unfamiliarity with it. Therefore, I am reporting the following case and reviewing the literature. REPORT OF A CASE Miss L. G., a dietitian 42 years of age, first consulted me on April 24, 1942. About eight weeks previously she and her mother had noticed an itching

Isolation of Typhus Rickettsia from Rat Mites During Epidemic in an Orphanage

Macxy predicted that rat and mouse may be the reservoirs and tick, mite, or flea may be the transmitters of typhus fever in the southern parts of the United States. This prediction had been satisfactorily fulfilled except for the possibility of mites as vectors., , , , While Shelmire and Dove, and Kodama and Kano have experimentally transmitted typhus Rickettsia in laboratory animals by rat mite, no special attention was attached to this vector as an important carrier of typhus Rickettsia. In this communication, we wish to present a first instance of isolation of typhus Rickettsia from mites naturally infected and to discuss briefly its possible epidemiological significance. A rat trapped in July, 1940, at the end of a typhus epidemic which has occurred in an orphanage was found to harbor 3 mites identified as Liponyssus bacoti. From them, a strain of typhus Rickettsia was established in guinea pig and white rat according to the following criteria: Fever in guinea pig and albino rat, positive Weil-Felix reaction in most of the inoculated rats, in some cases as high a titer as 1:320, recovery of Rickettsiæ on direct examination and cultivation of the tunica vaginalis of infected guinea pig, and finally, positive cross-immunity with a known strain of murine typhus. A second group of rat mites from the same orphanage 4 months after the epidemic showed suggestive findings on inoculation into albino rats but was not further studied. Material from the rat which harbored the first group of mites produced a suggestive typhus infection on inoculation into albino rats. Comment. The prediction of Macxy that the mite may be a vector of typhus fever has been further supported by the isolation of a strain of typhus Rickettsia from naturally infected mites during an epidemic.