Infected Fleas Research Articles

A review of immunization against human rickettsial diseases

1. 1. Recovery from a rickettsial infection is accompanied by the development of considerable immunity; therefore, protective vaccination is theoretically possible. 2. 2. In practice, difficulties are encountered because living vaccines may be dangerous, and dead rickettsias have relatively little immunizing power. 3. 3. These difficulties might be overcome by using vaccines of living but attenuated organisms or relatively large numbers of killed organisms. 4. 4. Large numbers of organisms are not conveniently obtainable as rickettsias will not grow in ordinary media. They can, however, multiply enormously in appropriate arthropods, and Parker and Spencer utilized this to prepare a satisfactory killed vaccine against Rocky Mountain spotted fever from phenol-formolized suspensions of ground-up infected ticks. 5. 5. Weigl prepared an effective typhus vaccine by emulsifying in phenolsaline the heavily infected intestines of artificially infected lice. By Weigl's technique, Mosing prepared a specific vaccine which he thought had some action against a trench fever-like disease. The labour involved limits production and Weigl's vaccine has also been criticized on the general ground that killed vaccines only give feeble, restricted and short-lived immunity. 6. 6. Infections can also be developed in laboratory animals and early attempts were made to use infected tissue suspensions as vaccines, but the small yields of rickettsias when killed failed to vaccinate satisfactorily. 7. 7. As living organisms, although attenuated, might give rise to accidental infections, the danger in typhus was diminished by using the relatively benign murine virus which, owing to cross immunity between it and classical typhus, can when living immunize against either infection. Although considerable cross immunity exists between classical and murine typhus, the enfeebled protective power of killed rickettsias is manifest in a much stricter specificity of the respective killed vaccines in the two diseases. 8. 8. Blanc and his colleagues rendered living murine virus from infected guineapigs innocuous by treating it with ox-bile; the virus is very unstable and a modification has been introduced whereby dried infected flea faeces, which retain their virulence for long periods, are used as the source of virus for the vaccine. Nicolle and Laigret attenuated a murine virus from guineapigs and rats by drying and coating it with egg yolk and olive oil; Laigret and Durand have introduced a further modification using mouse-brain passage virus. These vaccines normally produce only inapparent infections, reactions of vaccinial typhus being rare. Nevertheless, in certain circumstances, such reactions may not be negligible. 9. 9. Zinsser, disbelieving the reliability of controlled attenuation, attempted to obtain sufficient quantities of rickettsias for killed vaccines from animals heavily infected by having their resistance artificially lowered. 10. 10. Thus Zinsser and Castenada, with murine virus in rats irradiated with X-rays, obtained peritoneal accumulations of virus sufficiently rich to prepare a practical phenolized vaccine. Its protection against classical typhus was, however, poor, nor could they get satisfactory yields of classical virus from irradiated rats. 11. 11. Efforts are now being made to produce vaccines of various rickettsias grown in tissue cultures, and in the yolk sac and tissues of developing chicks; other experiments seek to obtain sufficient yields from animals by simpler methods. Durand and Sparrow recently reported an important technical advance whereby intranasal instillation of typhus viruses into etherized white mice results in a rapid and massive pulmonary infection, from which rich cell-free suspensions of rickettsias can be prepared. Utilizing this, Durand and Giroud have recently prepared mouse lung vaccines against classical typhus. 12. 12. Sera from convalescents, from those vaccinated or from animals artificially immunized, may confer good but brief passive immunity against rickettsial diseases; the curative action in declared infections is less certain. Combined sero-vaccination has been suggested to give typhus contacts immediate protection followed by active immunity.

Persistence of Sylvatic Plague

In June, 1916, sylvatic plague was first demonstrated in San Mateo County by gross anatomical examinations of squirrels (Citellus beecheyi). During the next 4 years infected rodents were again discovered by dissection. Between 1921 and 1931 no surveys were conducted. In 1932 to 1935 annually, a few hundred squirrels and rats were shot and autopsied; no gross anatomical lesions suggestive of plague were observed. During August and September of 1936, a total of 863 beecheyi squirrels were again examined with negative results. The fleas, which had been killed with chloroform, were removed from the animals and collected in physiological salt solution. A total of 18,729 fleas were thus assembled in 355 pools, which were stored at 3°C. for approximately 10 to 11 months since suitable facilities to examine them were not available. In 1937 the insects collected from the squirrels of the same area were pooled in 155 lots, carefully washed with salt solution, ground in a mortar and then injected subcutaneously into guinea pigs. Of the 155 pools so tested 6 produced fatal plague infections within 6 to 8 days. Two of the locations in the County where infected fleas were found in 1936 were recognized as the same colony or series of burrows proven to harbor diseased squirrels in the summer of 1916. These and similar observations indicate that sylvatic plague persists probably indefinitely in an area once invaded and that the gross anatomical examinations fail to detect rodent infections. Squirrels, just as rats, may harbor P. pestis without visible lesions. The biology of these latent infections is the subject of further investigations. Although the viability of P. pestis in stock cultures for many years is well known, the fact that the bacteria remained alive in the dead fleas soiled with a variety of microörganisms (B. coli, B. proteus, Cocci, etc.) held at ice box temperature is indeed noteworthy.

Societies and Academies

PARIS Academy of Sciences, July 31 (CM., 177, 365-432). The president announced the death of Edouard Qu©nu, member for the Section of Medicine and Surgery. A. LACROIX: A stony meteorite which fell in Morocco on August 22, 1932. R. FOSSE, P. DE GRAEVE and P. E. THOMAS: The transformation of the intermediate term of the permanganate oxidation of uric acid into allantoic acid, in the presence of the soya ferments and of potassium cyanide. CHARLES NICOLLE and L. BALOZET: Man is insensible to inoculation of the aphthous virus of known types, even in the form of a latent infection. CHARLES NICOLLE, J. LAIGRET and P. GIROUD: The transmission of typhus by bites and by ingestion of infected fleas. The ape can be infected by flea bites, rats by ingestion of infected fleas. The infections produced were of the latent type, none of the animals showing febrile symptoms. B. CABRERA and H. FAHLENBRACH: Diamagnetism and temperature. PAUL PASCAL and BONNMEMAN: The reversible passage of the dimetaphosphates to the condensed salts of Graham. Study of the metaphosphates produced by the dehydration of silver acid pyrophosphate and by heating silver hypophosphate at varying temperatures. G. B. GOUREWITCH: The canonical forms of a trivector in space of six dimensions. RENE DE POSSEL: The theory of measurement. The prolongation of an additive function of ensemble. TULLIO VIOLA: The points of convergence of general trigonometrical series. B. RIABOUCHINSKY: Total dissemination. P. DUMANOIS: Concerning the influence of the temperature on detonation in internal combustion motors. From the peroxide theory of detonation, the author concludes that if the temperature of the explosive mixture going into the motor cylinder be raised, the detonation should disappear. Experiments confirming this are described. J. LE ROUX: A new form of the Lorentz formul. J. SAVARD: The ionisation potential and formation of the molecule of hydrogen. ALEXIS GUERBILSKY: Piezo-electric crystal dynamometers in resonance vibration. J. SOLOMON: The effect of internal conversion. A discussion of the application of Dirac's theory of the electron to the explanation of the effect of internal conversion, that is, the absorption by an electron of a radioactive atom of the photon emitted by the nucleus. W. GENTNER: The absorption of very penetrating Î-rays. MARCEL LECOIN: The -radiation of radium E and of the active deposit of actinium. AUGUSTE LE THOMAS: The anomalies of the tempering of cast irons: their relation with the oxidation in the liquid state. ED. CHAUVENET and MLLE. J. BOULANGER: The compounds of zirconyl bromide with the alkaline bromides. Application of the calorimetric method indicated the formation of definite compounds of zirconyl bromide with the bromides of sodium, potassium, rubidium, csium and ammonium, but not with lithium bromide. The compound with csium bromide was isolated in crystals. O. MILLER and L. PIAUX: The Raman spectra of the cis-trans isomeric orthodimethylcyclohexanes. VOLMAR and BETZ: The emetics derived from mandelic and malic acids. The preparation and properties of sodium antimoniomandelate and sodium antimoniomalate are described. E. VELLINGER and G. RADULESCO: The antioxidising or antioxygen constituents of petrol prepared by cracking. It is suggested that the petrol passing below 170° C. should be refined and then mixed with the crude unrefined fraction passing between 170° C. and 180° C. MME. GUAISNET-PILAUD: The crystallographic constants of the hydrates of the phenyl-methylethyl betaines and of the phenylmethylpropylbetaines. J. GUBLER: The presence of the Trias at Cambogia. A. DUPRIER and G. COLLADO: The fluctuations of the terrestrial electric field. Experiments made at Paris and Madrid show that the continuous fluctuations of the electric field cannot be regarded as being due to local irregular disturbances. H. COLIN and J. AUGIER: Floridoside, trehalose and glycogen in red fresh-water Alg (Lemanea, Sacheria). J. ANDR THOMAS: The evolution of prolonged cultures of the wall of the umbilical vesicle, in the embryo of the chick. A. POLICARD: The study by micro-incineration of the distribution of fixed mineral matter in the spermatozoids of mammals. In the spermatozoids of both man and rat the method of micro-incineration shows at the level of the head the presence of a part poor in mineral matter and a posterior part containing much more. SWIGEL and THODORE POSTERNAK: The phosphorus containing nucleus of the ichtulin of the pike. MME. ANDRE ROCHE: The comparative study of the chemical constitution of normal animal muscle, dead through total starvation or through protein starvation.

Typhus Fever: Transmission of Endemic Typhus by Rubbing Either Crushed Infected Fleas or Infected Flea Feces into Wounds

Typhus Fever: Transmission of Endemic Typhus by Rubbing Either Crushed Infected Fleas or Infected Flea Feces into Wounds

The yearly variations in plague in India in relation to climate: Forecasting epidemics

It has long been known that plague in India, and elsewhere, has a definite seasonal incidence year after year in the same area, although the months of maximum prevalence vary in different provinces. E. H. Hankin as early as 1905 pointed out the disappearance of dog fleas in the hot weather in Agra, and he suggested that a similar decline in the rat fleas might account for the great fall in plague in the United Provinces of India during the hot season. The Extensive and valuable Reports on Plague Investigations in India, published in the Journal of Hygiene from 1906 to 1917, contain numerous data on the subject, and they bring out the unfavourable effects of high temperature and low humidity on the duration of life of rat fleas separated from their hosts, and on their rate of multiplication, and they thus accounted for the seasonal incidence of the disease in different areas of India. Further, the work of Bacot in England and of unnamed workers in Poona on the bionomics of fleas showed that relative humidities below 50° to 55° F. and high temperatures are unfavourable in England, and that in Poona, on the Deccan plateau of Western India, the life of fleas was five times as great in August, with an 8 a. m. relative humidity of 80 per cent., as with one of 45 per cent. in April and early May, when plague, is at a minimum in that area, where the temperatures are moderate and play much less part than humidity in controlling the plague season. Moreover, studies of the seasonal incidence of plague in different parts of India by the same investigators, working under the Advisory Committee nominated by the India Office, the Royal Society and the Lister Institute, showed that a temperature of 85° F. caused a more rapid disappearance of plague bacilli from the stomach of fleas, with reduced power of infecting animals, as compared with a temperature of 70° F., and with the low mean temperature of 50° F. a large number of the infected rats died before plague bacilli appeared in their blood, so that their fleas had no chance of becoming infected. Rat fleas were also more numerous during the height of the plague season, so that climatic conditions clearly acted by reducing the number of infected fleas. The incidence of plague in different areas of India was also reported on by R. St. John Brooks (1) in relation to temperature and saturation deficiency, the latter term indicating "the difference between the actual tension of aqueous vapour present in the atmosphere at the temperature in question and the tension of aqueous vapour that would be present in a saturated atmosphere at the same temperature." It is thus a measure of the drying capacity of the air, and Brooks concluded that a degree of dryness indicated by a saturation deficiency of 0·300 inch (measured in terms of mercury) suffices to prevent plague continuing to be epidemic, if the mean temperature is also over 80° F., and that a high saturation deficiency rapidly brings an epidemic to an end even with a temperature below 80° F., but an epidemic may commence and increase with a temperature over 80° F.., if the saturation deficiency is below 0·300. Moreover, in certain places, including Java and Mauritius, with constantly favourable temperature and saturation deficiency, the disease may be prevalent indifferently at any season of the year.

Notes onTrypanosoma lewisiand its Relation to CertainArthropoda

1.Trypanosoma lewisiwas found in 25% of rats caught in and about Cambridge. Of these rats 12% were young, 33% adult, and 29% old. In this region the endetnicity was localised to certain areas.2. Fleas (C. fasciatusandC. agyrtes) were constantly found associated with wild rats infected withT. lewisi. We think that these two species of fleas are the chief carriers of the parasite from rat to rat in this region.3. We tried transmission experiments with fleas (C. fasciatusandC. agyrtes), lice (H. spinulosus), bugs (A. lectularia), ticks (O. moubata, nymphs and adults), andGamasussp., but only obtained a positive result by the agency of fleas.4. In the transmission experiments the arthropod was transferred from an infected to an uninfected animal. 16% of 138 experiments with fleas were successful, 80—98% of the fleas used were non-infective, while 2—20% were infective.5. Distant transmission occurs with fleas. This was observed by one of us in January, 1909.6. ‘Mechanical’ transmission occurs sometimes with fleas.7. Infective fleas do not transmit the power of infection to their young.8. The mechanism of infection in the case of mechanical transmission is by the bite of the flea; in the case of the distant infection it is not so.9. The infective forms ofT. lewisifor distant transmission are probably the ‘small trypanosomes’ which we have described elsewhere (1910). The forms ofT. lewisifound prior to the small trypanosomes in the developmental cycle are not infective.10. The development of the trypanosomes in the flea is not interfered with by the flea feeding on a rat immune to the disease.11. Seventeen experiments with lice were performed, but no transmission was obtained by their agency. 1139 lice were used. No confirmation of Baldrey's infective cycle in lice could be obtained.12. We could trace no connection between transmission of infection by lice and the presence in them of ‘developmental forms.’13. No transmission ofT. lewisiby other arthropods was obtained. These negative results had no connection with the presence in the arthropods of ‘developmental forms.’In conclusion we would like to thank Professor Nuttall for his kindness in inoculating our animals and providing us with the material for our experiments, and for his interest and advice in our work.

XXVI. The part played by insects in the epidemiology of plague

(1) All fleas and bugs which have sucked the blood of animals dying from plague contain plague1 microbes.(2) Fleas and bugs which have sucked the blood of animals which are suffering from plague only contain plague microbes when the bites have been inflicted from 12 to 26 hours before the death of the animals, that is, during that period of their illness when their blood contains plague bacilli.(3) The vitality and virulence of the plague microbes are preserved in these insects.(4) Plague bacilli may be found in fleas from four to six days after they have sucked the blood of an animal dying with plague. In bugs, not previously starved or starved only for a short time (one to seven days), the plague microbes disappear on the third day; in those that have been starved for 4 to 4½ months, after eight or nine days.(5) The numbers of plague microbes in the infected fleas and bugs increase during the first few days.(6) The faeces of infected fleas and bugs contain virulent plague microbes as long as they persist in the alimentary canal of these insects.(7) Animals could not be infected by the bites of fleas and bugs which had been infected by animals whose own infection had been occasioned by a culture of small virulence, notwithstanding the fact that the insects may be found to contain abundant plague microbes.(8) Fleas and bugs that have fed upon animals which have been infected by cultures of high virulence convey infection by means of bites, and the more certainly so the more virulent the culture with which the first animal was inoculated.(9) The local inflammatory reaction in animals which have died from plague occasioned by the bites of infected insects is either very slight or absent. In the latter case it is only by the situation of the primary bubo that one can approximately identify the area through which the plague infection entered the organism.(10) Infected fleas communicate the disease to healthy animals for three days after infection. Infected bugs have the power of doing so for five days.(11) It was not found possible for more than two animals to be infected by the bites of the same bugs.(12) The crushing of infected bugs in situ during the process of biting, occasioned in the majority of cases the infection of the healthy animal with plague.(13) The injury to the skin occasioned by the bite of bugs or fleas offers a channel through which plague microbes can easily enter the body and occasion death from plague.(14) Crushed infected bugs and fleas and their faeces, like other plague material, can infect through the small punctures of the skin caused by the bites of bugs and fleas, but only for a short time after the infliction of these bites.(15) In the case of linen and other fabrics soiled by crushing infected fleas and bugs on them, or by the faeces of these insects, the plague microbes can under favourable conditions remain alive and virulent during more than five months.(16) Chemical disinfectants do not in the ordinary course of application kill plague microbes in infected fleas and bugs.(17) The rat flea Typhlopsylla musculi does not bite human beings.(18) Human fleas do bite rats.(19) Fleas found on dogs and cats bite both human beings and rats.(20) Human fleas and fleas found on cats and dogs can live on rats as casual parasites, and therefore can under certain conditions play a part in the transmission of plague from rats to human beings, and vice versa.

XVII. Experiments in plague houses in Bombay

1. In 19 out of 100 experiments guinea-pigs allowed to run free in houses which were presumably plague infected developed the disease and died.2. On three occasions, namely, on every occasion on which the experiment was made, fleas transferred from plague-infected rats found in houses infected fresh guinea-pigs in the laboratory.3. Rat fleas, caught on guinea-pigs in plague houses and transferred to fresh guinea-pigs, transmitted the disease in 35% of the cases.4. A census of rat fleas in houses in Bombay, which were proved plague infected, indicated that rat fleas were 12 times as numerous as in control houses; and that in presumably infected houses rat fleas were four times as numerous as in control houses.5. In 41 out of 130 fleas taken on guinea-pigs in plague-infected houses, bacilli microscopically indistinguishable from plague were found in the stomach.6. In the case of 24 of the 27 houses definitely proved to be plague infected, dead rats had been found shortly before the experiments were made.