Leslie A. Stauber

Characterization of Strains of Leishmania donovani.

Abstract Even with the most standardized procedures yet available for in vivo trials, the intrastrain variations in the course of infection of Leishmania donovani in the hamster permit no easy assessment of variations among those tested by us from several parts of the world. Although more than a thousand hamsters have been used in the present evaluation, some of the strain differences observed may yet need further qualification. Upon intravascular introduction of similar numbers of parasites into hamsters, African, Mediterranean and Burmese strains of L. donovani appear to have distinct characteristics: early rates of accumulation of parasites, peak numbers in spleen and liver, and time to death all differ. Parasite counts in liver appear better to express the number differences than do those in the spleen under the experimental conditions observed. The African strains are most virulent and the Burmese least virulent, although all strains tested lead to the death of the hamster. Preliminary studies of some of the same strains of parasites in the mouse confirm the differences noted above except, of course, that deaths due to L. donovani in the mouse have not been observed.

The effect of parasitism and starvation on carbohydrate reserves of Biomphalaria glabrata

Abstract In Biomphalaria glabrata parasitized by Schistosoma mansoni there was an increase in relative weight of the digestive gland-gonad complex and a decrease in glycogen in that complex and in the remainder of the carcass by day 25. Glycogen levels further decreased close to zero and remained at this low level for the duration of the experiment. Relative weight of the digestive gland-gonad reached a peak at day 30 and decreased toward normal by day 40. Galactogen levels in the albumen gland, although decreased slightly, were not significantly lower than in normal snails. In starved snails, glycogen and galactogen decreased significantly below normal at day 21 and remained at a low level until the experiment ended. This study raises the possibility that starvation of the host by the parasite may play a significant role in the pathology observed in this infection.

Experimental hexamitiasis in the oyster Crassostrea virginica

Abstract In vitro growth characteristics of Hexamita sp. and course of experimental hexamitiasis initiated in oysters via the oral and intracardial route were used in an attempt to analyze the controversial issue of whether Hexamita is an oyster pathogen. In culture, the growth of Hexamita is temperature-dependent; the flagellate multiplies 1000 times at 6° and 12°C in 15 and 6 days, respectively. At 18° and 25° its growth is limited to 100 times to 10 times in 3 to 4 days. When 3.2 × 10 6 Hexamita were injected into the oyster intracardially at 6°C, the flagellates increased in numbers after a lag period of 8 days and all oysters died within 18 days. After injection of 4.0 × 10 5 Hexamita per oyster at 12°C 9 of 10 died within 20 days. In the one survivor, the count of Hexamita in heart blood decreased steadily after the crisis on the 8th day as the oyster overcame the infection. When the dosage injected was reduced to 1.0 × 10 3 Hexamita per oyster and the oysters were kept at 12°C, half survived. At 18°C when 8.8 × 10 5 Hexamita were inoculated into the oyster, not even a patent infection was observed in the 2-week period. No conclusive results were obtained from a series of experiments designed to ascetain whether Hexamita sp. introduced into the oyster via the oral route was able to breach the epithelial barrier. However, implications are discussed. The data demonstrate conclusively that physiological conditions of the oyster, the reproductive capacity and the pathogenicity of the microorganism, and the proper manipulation of experimental conditions (e.g., ambient temperature, size of inoculum, route of entry, etc.) can alter the course of infection.

IMMUNITY TO LEISHMANIA.

Since their discovery by Borovsky in 1898 (see C. A. Hoare, 1938) studies on Leishmania have emphasized other than immunological aspects. Most. of the literature deals with descriptions of infections in man and animals, notations of cases appearing sporadically in many parts of the world, chemotherapy, histopathology, epidemiology, transmission, and diagnosis. Studies in the laboratory have dealt most frequently with drug-screening trials, cultivation in virro, and transmission, and-where immunological procedures were used-they were used more for diagnostic purposes than for the elucidation of the fundamentals of infection and resistance in the vertebrate hosts. However, important progress has been made, although much is yet to be learned. For the sake of convenience the dermal and visceral infections will be dealt with separately. Nevertheless, the findings of Kirk (1938) and others of initial local lesions in African kala azar and the disseminated aspects of some dermal infections (lymphatic involvement, more or less extensive mucocutaneous lesions, and post kala azar dermal leishmaniasis) emphasize both the diversity and overlap of host-parasite interaction in leishmaniasis. The chronic, insidious nature of the infection in man and animals, with long-term association between host and parasite, allows ample time for intercurrent events to influence the course of infection. Finally, the intracellular position of the organisms in the vertebrate host poses many of the same problems in host-parasite interaction seen in tuberculosis, leprosy, and toxoplasmosis.

Eperythrozoon coccoides: Influence on Course of Infection of Plasmodium chabaudi in Mouse

Mice infected with Plasmodium chabaudi obtained from two sources were found to be contaminated with Eperythrozoon coccoides. At each transfer of blood parasitized with plasmodia, eperythrozoa were also passed. In the presence of these organisms, the malarial infection assumed a low-level, chronic course infrequently resulting in death of the mice. When the eperythrozoa were eliminated through treatment with oxophenarsine hydrochloride, the malarial infection took an acute course always ending in death.

Leishmania donovani: Antibody response to chicken ovalbumin by infected golden hamsters☆

Abstract The individual antibody response to ovalbumin (OA) was studied in groups of hamsters infected with Leishmania donovani . Each group consisted of two infected and two uninfected hamsters. All the animals were immunized to OA at intervals, prior to or following the introduced infection. One week after the initial immunization, each hamster received a second injection making a total of 10 mg OA. This procedure was begun with Group 1, 12 days before infection and was continued in new groups of four hamsters every 3 days until there were 19 groups under study. Each hamster, 24 days after the initial sensitization to OA, was anesthetized, weighed, exsanguinated, and necropsied. Antibody titers to OA measured by tanned cell hemagglutination (HA) from the infected vs. the uninfected hamsters were similar until a moderately severe infection developed (900 “Total Spleen Lds”). Above this level of parasitization the anti-OA titers of the infected animals were lower despite increased concentrations of gamma globulin in their serum as shown by electrophoretic studies. The titers of the uninfected animals remained in the same range throughout the experiment. The possible explanations for the depression of the immune response are discussed.

Electrophoretic patterns of the serum proteins of chinchillas and hamsters infected with Leishmania donovani.

The agent of so-called “salmon poisoning disease” of dogs on the Pacific Coast of the USA, first reported by Cordy and Gorham (1950), is an intracytoplasmic, rickettsia-like, sometimes pleomorphic microorganism found particularly in the reticulo-endothelial cells of lymphoid tissues of infected Canidae. It is transmitted in nature to members of the Canidae by ingestion of fish containing encysted cercariae of the intestinal fluke, Nanophyetus salmincola. The natural, developmental cycle of this trematode includes snails, Gonidbasis plicifera silicula, and fish of the family Salmonidae. The infection is transmissible in series by blood and by fresh or frozen node tissues of infected to susceptible dogs as well as by suspension of adult flukes. There is an incubation period of 8 to 10 days followed by several days of an acute febrile episode. Mortality is high. When there is occasional recovery, the dogs are solidly immune. Reasons are presented for assigning this pathogen to the family Rickettsiaceae by modifying the vector character of the family from “arthropod-borne” to “invertebrate-borne” agents, and for having given this the name of Neorickettsia helminthēcaPhilip, Hadlow, and Hughes (1953).

14C Uptake by Schistosoma mansoni from Biomphalaria glabrata exposed to 14C-glucose☆

Abstract Exposure of Biomphalaria glabrata infected with Schistosoma mansoni to 14 C-glucose results in a greater uptake of original total snail label by the parasitized digestive gland-gonad, site of the developing daughter sporocysts and cercariae, than by the digestive gland-gonad of control animals. As a consequence of this greater uptake by the infected digestive gland-gonad, the albumen gland and remainder of the carcass of parasitized snails receive less label than do those areas in normal snails. Emergence of cercariae from the snail and daughter sporocyst mass account for a diversion of 12.6% of original total label from the infected snail itself. This diversion of label from the snail to the parasite may explain carbohydrate depletion in parasitized snails.

Leishmaniasis in the Sudan Republic. 29. Comparison and epidemiological implications of experimental canine infections with Sudanese, Mediterranean, and Kenyan strains of Leishmania donovani.

Three strains of Leishmania donovani from different geographic areas [Sudan, Mediterranean (Sicily), and Kenya] were studied comparatively in puppies and adult dogs under controlled laboratory conditions. Hematological, serological, and endocrinological investigations were included. However, only the course of infection is discussed here. The growth curve of the parasites in the liver was studied, as well as the pattern of infection in different organs at different periods. The pattern of both liver and spleen infections caused by the Mediterranean strain proved to be different from and more variable than that caused by the Sudan and Kenya strains, which developed similarly except for an earlier decline of parasite numbers followed by spontaneous cure in the Kenya strain. Assuming the results from these strains to be fully representative of their respective areas, it is suggested that the dog may be excluded as a probable natural reservoir of L. donovani in Kenya and that its role as a vertebrate reservoir in the Sudan is doubtful. The results confirm that the dog is an efficient reservoir of the pathogen in the Mediterranean area. In areas where kala azar is endemic, dogs are frequently abundant and closely associated with man. They play an important role as reservoir hosts of Leishmania donovani in China, several foci in the USSR, Brazil, and many localities in the Mediterranean basin. Canine leishmaniasis has been reported but is inadequately documented in several areas of Africa. No canine infections have been reported from Kenya (Henderson, 1937; Heisch, 1954, 1963) or the Sudan (Archibald and Mansour, 1937; Kirk, 1956; Hoogstraal et al., 1963; Hoogstraal and Heyneman, 1969). The paradoxical discrepancies between recorded distributions of human and canine infections require experimental investigation to evaluate the interrelationships between different geoReceived for publication 8 January 1970. * Parasitology Department, U. S. Naval Medical Research Unit Number Three, Cairo, Egypt, UAR. This work was undertaken at the Bureau of Biological Research, Rutgers-The State University, under the auspices of Office of Naval Research Postgraduate Research Grants NONR00038-65 and NONR-0137-66. From Research Project MF12.524.009-3001B, Bureau of Medicine and Surgery, Department of the Navy, Washington, D. C. The opinions and assertions contained herein are the private ones of the authors and are not to be construed as official or as reflecting the views of the Department of the Navy or of the naval service at large. t Bureau of Biological Research, Rutgers-The State University, New Brunswick, New Jersey 08903. graphical strains of the organism and the dog, and to assess the role of the dog in kala azar epidemiology in different areas. This report, abstracted from a more extensive study to be published elsewhere, is intended chiefly to elucidate factors influencing the epidemiological role of the dog in Central Sudan and to contribute to the results of an extensive field and laboratory study of kala azar in that country (Hoogstraal and Heyneman, 1969). Although several studies have been devoted to L. donovani infection in the dog, none has used standardized procedures for inoculation, sampling, and evaluation. Stauber (1955) established a quantitative procedure that makes it possible to follow the course of infection with reasonable accuracy. Stauber et al. (1966) emphasized the importance of standardized quantitative procedures and Stauber (1966) applied these criteria to a comparison of interstrain variation in L. donovani. These studies established that intravascular inoculation of relatively large numbers of organisms is required to produce infections of relatively low variability for accurate estimates in vivo of L. donovani strain differences. These techniques have been employed in the present study. MATERIALS AND METHODS Three groups of 4 adult dogs (average age 5 years) and 5 groups of puppies, at least 4 in each group from the same litter (average age 4 weeks), were infected with the following strains of Leishmania donovani.

Eperythrozoon coccoides and rodent malaria: Plasmodium chabaudi and Plasmodium berghei.

Abstract Interrelationships of dual infections of Eperythrozoon coccoides and Plasmodium chabaudi and E. coccoides and P. berghei were examined. In concurrent infections the E. coccoides patent period was lengthened. The P. chabaudi infection was less severe and as high as 100% survival was noted. In some cases the P. berghei infection was slower in developing but death invariably occurred. The diverse effect of E. coccoides on the two species of malaria parasites was correlated with a difference in extent of inhibition by the eperythrozoa and with the preference of P. berghei for reticulocytes as host cells. Both the dosage size of eperythrozoa and the time of eperythrozoan inoculation relative to the time of malaria inoculation were critical determinants of the outcome. The course of the E. coccoides infection alone was found to be influenced by the dosage of organisms injected. The time to patency, maximum parasitemia, maximum anemia, and reticulocytosis was delayed approximately 1 day with each 1000-fold reduction in inoculum size.