Library

Notes: Three new species of Trypanosomatidae were isolated from three species of bugs: Leptomonas leptoglossi from Leptoglossus phyllopus, Crithidia acanthocephali from Acanthocephala femorata, and Blastocrithidia euschisti from Euschistus servus. All were cultured axenically and on avian embryo membranes. In addition to differences in morphology the three organisms displayed different growth rates in the chorio-allantoic fluids of duck and chick embryos incubated at 30°C. L. leptoglossi grew most abundantly. B. euschisti barely maintained itself while C. acanthocephali occupied an intermediate position.When the temperature of incubation was raised to 37°C, there was continued multiplication of L. leptoglossi and C. acanthocephali, but there was no growth of B. euschisti in either duck or chick embryos.It is suggested that the criteria of morphology, cultural characteristics in vitro and in vivo, plus physiological characters be used as future aids in classification of the Trypanosomatidae.

Notes: SYNOPSIS. A laboratory colony of Oncopeltus fasciatus was found to be infected with Leptomonas oncopelti. Inasmuch as the parasite is transmitted from parent to offspring an opportunity presented itself to study the biology and transmission of this parasite under controlled laboratory conditions. An apparatus for observing individual bugs was designed and the presence or absence of flagellates in the feces determined. Flagellates were not shed until the bugs became adults after which they appeared in every defecation. Dissection of infected bugs revealed that flagellates were not present in the rectum until adulthood. Further studies indicated that in the midgut of the insect there is a departure from binary fission to budding. The nucleus divides and one of the newly formed nuclei migrates toward a newly formed kinetoplast. Rarely there is still another kinetoplast/nucleus division. In the event the new axoneme grows within the cytoplasmic sheath of the parent flagellum, smaller organisms produced by unequal cytokinesis remain attached. If the axoneme grows free, the smaller daughter organisms become free-swimming. Passage into the rectum of the adult bugs causes a rounding up of all parasites although the leishmaniform organisms continue to divide. It is presumed that infection of clean bugs is accomplished by the ingestion of leishmaniform organisms through a common water source. The reason for the presence of flagellates in the rectum of the adult but not in the nymphal insect and the mechanism responsible for the change from binary to unequal fission are not known.

Notes: Available evidence indicates that many of the antiprotozoal drugs currently in use significantly modify the immune response of the host. The effect depends on both the drug and the host. Some drugs enhance the immune response, some are immuno-suppressants, and others enhance some types of immune mechanisms while suppressing others. Future efforts in the development of antiprotozoal drugs should consider their effects on both the parasite and the immune response of the host. Also in the chemotherapy of protozoal infections consideration should be given to the combined usage of immunoenhancing agents and antiprotozoal drugs.

Notes: SYNOPSIS. Trypanosomatid-free plants of the family Asclepiadaceae identified as Asclepias syriaca, A. curassavica, A. incarnata, Stephanotis floribunda, Seutera maritima, Amphistelma scoparia and plants of the family Euphorbiaceae identified as Euphorbia tirucalli, E. trigona, and Pedilanthus tithymaloides were exposed to the bite of the bug, Oncopeltus fasciatus, infected with Phytomonas elmassiani, a flagellate which occurs naturally in A. syriaca and O. fasciatus. Two weeks subsequent to exposure to laboratory-infected oncopeltids all the experimental Asclepiadaceae were infected. The mean length of the protozoa varied depending on the host plant. The flagellates in A. syriaca, A. curassavica, and A. incarnata were shorter than those in S. floribunda, S. maritima, and A. scoparia.None of the Euphorbiaceae became infected.

Notes: SYNOPSIS. After several years of field work devoted primarily to determining the incidence of infection of the common milkweed Asclepias syriaca with the trypanosomatid Phytomonas elmassiani, the life cycle of this parasite was determined under controlled conditions. Upon ingestion of phytomonads by the bug Oncopeltus fasciatus, reproduction apparently ceases but growth of individual phytomonads continues until they assume relatively giant proportions. Ten days after ingestion, giant forms are found in the hemocoel of the bug and by 12 days similar forms are present in the salivary glands. In this latter organ, unequal fission takes place with the ultimate formation of numerous forms similar to those found in the plant. Within 2 weeks after these infected bugs had fed on milkweeds, parasites were detected in the latex of formerly non-parasitized plants. The lack of reproduction in the alimentary tract, the formation of giant forms, and the migration through the hemocoel to the salivary glands contrast markedly with the development of Leptomonas oncoptlti in the same bug. In the latter organism, budding leads to the formation of leishmaniform organisms which pass out with feces and are presumably the infective stage of the leptomonad.

Notes: SYNOPSIS. Dissections of Triatoma infestans and Rhodnius prolixus at various intervals after experimental infection with insect Trypanosomatidae of the genera Blastocrithidia and Crithidia (B. euschisti, C. luciliae, C. acanthocephali and C. mellificae) disclosed the protozoa to be surviving and in most instances undergoing reproduction in the experimental bugs for as long as 2 months following infection. Epimastigotes and amastigotes were seen in bugs infected with B. euschisti and choanomastigotes and amastigotes were observed in insects experimentally infected with the Crithidia. Since C. acanthocephali and C. luciliae were from clones, this is the 1st finding of these 2 structural types in this genus using cultures originating from a single choanomastigote.In view of the loose host specificity of the insect Trypanosomatidae as further emphasized by this work, it would appear that the necessity is increased for field workers in trypanosomiasis and leishmaniasis areas of the world to become well acquainted with the infective potentialities of the insect trypanosomatids of their areas for the vectors of Trypanosoma and Leishmania along with the possible association in nature of these vectors with insects which might harbor insect-limited Trypanosomatidae.

Notes: SYNOPSIS. As a part of an investigation of speciation in the Trypanosomatidae six species of crithidia were studied to determine their antigenic relationships. Antisera were prepared in chickens by means of three intravenous injections of several million crithidia and the titer and tests accomplished by using the agglutination technic. Titers against homologous protozoa averaged 1/640 with the highest titer recorded being 1/5120. Each antiserum was first tested against its homologous antigen then against each of the various crithidia. Results indicated the possibility that the crithidia isolated from hemiptera (C. acanthocephali, crithidia from Arilus cristatus and crithidia from Euryophthalmus davisi) were identical as far as our tests could determine. Those isolated from dipterons (C. fasciculata, C. luciliae) as well as C. (Strigomonas) oncopelti which was presumably isolated either from Oncopeltus fasciatus or the milkweed, Asclepias syriaca, were likewise identical. Each antiserum was adsorbed by each antigen and the serum tested against the homologous antigen. Again, with one possible exception, the close affinity between the dipteran flagellates (plus C. oncopelti) was established as was that between the flagellates of the hemipterons. Other than an occasional reaction, there were no cross reactions between the two groups of crithidia.

Notes: SYNOPSIS. In an effort to determine the degree of host specificity and morphology of the insect trypanosomatids in a presumably foreign host, individuals of a laboratory colony of the hemipteron Oncopeltus fasciatus were given intra-rectal injections with various species of axenically cultured parasites. Crithidia isolated from the hemipterons Acanthocephala femorata, Euryophthalmus davisi, and Arilus cristatus, as well as those from the dipterons Phaenicia sericata and Culex pipiens, and Crithidia (Strigomonas) oncopelti presumably isolated from O. fasciatus or Asclepias syriaca, demonstrated extensive multiplication whereas a leptomonad from the hemipteron Leptoglossus phyllopus and a blastocrithidian from the hemipteron Euschistus servus underwent little reproduction and disappeared after 8 and 25 days respectively. Another blastocrithidian taken from the hemipteron Melanolestes picipos flourished and has been transferred through 7 generations of O. fasciatus. None of the crithidia were transmitted although numerous flagellates and leishmaniform bodies were observed in the feces of bugs injected with all species.The crithidia in the gut of O. fasciatus were somewhat more elongated than culture forms and this appeared to be particularly marked in the dipteron group. In bugs injected with C. acanthocephali and C. oncopelti a few specimens were seen with the kinetoplast posterior to the nucleus. Leptomonas leptoglossi enlarged markedly when injected into the gut of O. fasciatus and in many organisms the nucleus was displaced to the posterior half of the body. There was no apparent change in the morphology of the two blastocrithidia in this host.Although some minor morphological changes were observed, this work in general supports the view of Wallace that Crithidia is a distinct genus and probably does not represent a stage in the life cycle of other organisms.

Notes: Quantitative methods were used to (a) determine the density of Trypanosoma cruzi in organs of CF1 mice following intraperitoneal inoculation of 50,000 trypomastigotes of a Brazil strain of T. cruzi and (b) study the relation of the numbers of these intracellular stages to the numbers of trypomastigotes in the blood. Tissue stages (predominantly amastigotes) in heart, skeletal muscle (triceps), diaphragm, cerebrum, cerebellum, and musculature of stomach, duodenum, esophagus, jejunum, cecum, and rectum increased in numbers during the 1st 3 weeks of infection, reached maximum density 21–28 days after inoculation and subsequently declined in numbers until mice were histologically negative for intracellular parasites by 30–40 days. The density of tissue stages in the urinary bladder, uterine body, and ileum was similar with the exception that maximum numbers of parasites were observed slightly earlier at 15 days.The greatest density of intracellular stages was seen in heart, urinary bladder, diaphragm, and triceps muscle where mean counts of 44.6–60.0 × 106 parasites/cc of muscle were recorded while maximum density of parasites in the uterine body, cerebrum, stomach, cerebellum, duodenum, esophagus, jejunum, ileum, cecum, and rectum was 13.0 × 106/cc of muscle or less. Amastigotes were not observed in sections of lymph node, thymus, salivary glands, liver, spleen, or kidney and only a single pseudocyst containing 5 amastigotes was seen in lung. With the exception of the brain and lung, intracellular parasites were located exclusively in the musculature.Trypomastigotes in the blood increased during the 1st 3 weeks of infection, reached maximum numbers 21–28 days after initiation of infection, and subsequently decreased until by 30–40 days parasites were observed only rarely in the blood of a few animals. Thus generally close correlation was noted between the numbers of intracellular stages of T. cruzi in the organs and trypomastigotes in the blood throughout acute Chagas’ disease in mice as evidenced by the concomitant increase in numbers of both stages, the coincidence of days of maximum parasite levels, and the simultaneous decline in numbers of both stages.The mean number of parasites/pseudocyst section varied in the organs studied. Of the 15 positive organs studied, the pseudocyst sections in skeletal muscle contained the highest mean number of parasites (64.3 parasites/pseudocyst section) and those pseudocyst sections seen in the musculature of the small intestine contained the lowest mean number (5.5–6.8 parasites/pseudocyst section respectively in ileum and jejunum).Serial sections of skeletal muscle, heart, urinary bladder, and stomach revealed the largest pseudocysts in skeletal muscle while those in the musculature of the urinary bladder were the smallest.