Panama Strain Research Articles

Characterization of Leishmania spp. by isozyme electrophoresis.

In this study, isozyme patterns for 14 different enzymes were compared for culture strains of Leishmania braziliensis, L. hertigi, L. mexicana, L. donovani, L. tropica, and L. adleri. The isozyme separation was made by means of cellulose acetate electrophoresis. Each of the species had distinct isozyme patterns for aspartate aminotransferase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, and fructokinase. For other enzymes, two or more species had identically migrating bands; however, by using combinations of the other 10 enzymes it was possible to separate any one of the six species. In addition to these interspecific differences the Panama strains of L. braziliensis had two different malic dehydrogenase isozyme patterns; therefore, they fell into two distinct groups. These strains otherwise had identical isozyme patterns.

Leishmania braziliensis: Dissemination of panamanian strains in golden hamsters

Dissemination of Panamanian strains of Leishmania braziliensis was observed in experimentally infected golden hamsters, Mesocricetus auratus, during the characterization of 164 strains isolated from patients (67), two species of edentates (88), and dogs (9). A total of 614 hamsters was employed in these studies. Hamsters were inoculated intradermally in the nose with 5–10 × 10 6 promastigotes from cultures of strains in their first to third passage in vitro. Parasites were recovered by culture from skin samples, viscera, blood and bone marrow. All strains studied disseminated to various areas of the skin and to the ear pinnae. Highest incidence of dissemination occurred in the skin from the tip of the tail, feet, and ears. Positive cultures obtained from liver and spleen were not considered as evidence for metastasis since they may have been due to the transitory presence in the blood of rare parasitized macrophages. Dissemination of various areas of the body was directly proportional to the length of the postinoculation period of the sloth strains.

PENAEID REARED BROOD STOCK: CLOSING THE CYCLE OF P. monodon, P. stylirostris AND P. vannamei

ABSTRACTThree shrimp species, Penaeus monodon, P. stylirostris (Panama and Mexican strains) and P. vannamei have matured and spawned in captivity at the Centre Océanologique du Pacifique (COP) laboratory. The shrimp, originally stocked as juveniles or postlarvae, were reared to adult size in tanks and ponds and have completed the cycle: F3 generation for P. monodon, F2 for P. stylirostris (Panama strain) and P. vannamei and F1 for P. stylirostris (Mexican strain). Maturation occurs naturally under our rearing conditions or is induced by unilateral eyestalk ablation. Details are given on mating behavior, ovarian development, number of spawnings, egg viability and maintenance of captive brood stock. Partial results so far obtained for P. monodon and P. stylirostris clearly show a reared brood stock could sustain a commercial hatchery.

Radiation inactivation ofSalmonella panama andEscherichia coli K 12 present on deep-frozen broiler carcasses

Low doses of ionizing radiation have been used to extend the shelf life of refrigerated poultry carcasses and to reduce the numbers of Salmonellae present. This report gives results of experiments on irradiation of deep-frozen poultry carcasses which were, before freezing, artificially contaminated withSalmonella panama and with a nalidixic acid-resistantEscherichia coli K 12. The D-values (decimal reduction) obtained with the inoculated carcasses were compared with D-values obtained with carcasses which were slaughtered in the normal way. The D-values forS.panama and forE.coli K 12 were 64.9 krad and 55.9 krad in the dripwater. Under commercial conditions approximately 100 krad were required for one decimal reduction of the Enterobacteriaceae present. The D-values estimated on the skin were higher forS.panama than forE. coli K 12 (128.6 krad vs 57.6 krad). If it is assumed that 1 positive carcass in 10,000 is allowed, the deep-frozen carcasses should be irradiated with doses of at least 700 krad to be sure of the absence of the testedS. panama strain.

Autogenous egg production in the salt-marsh mosquito, Aedes taeniorhynchus.

1. A total of 17 populations of Aedes taeniorhynchus were examined for the occurrence of autogeny. Every population contained some autogenous as well as some anautogenous females. In general, populations from the tropics and subtropics had higher rates of autogeny than did temperate zone populations. A major exception to this pattern was a Panama strain where less than 1% of the females were autogenous.2. Autogenous and anautogenous females occurred in the same reproductive populations. The progeny derived from individual, wild-caught females often contained both reproductive types.3. The mean fecundity was often less than 30 eggs per autogenous female in those populations where the occurrence of autogeny was rare or infrequent. In contrast, significantly higher levels of fecundity were associated with all populations that contained mostly autogenous females. Geographical variation in autogenous fecundity appears to be regulated by polygenic factors.4. We compared the blood-feeding characteristics and requirements of two mosquito populations in southern Florida. At Flamingo, Florida, only 8.1% of the females collected with power aspirators were engorged, whereas at Big Pine Key, Florida the engorgement rate was 20.9%. Approximately 80% of all females from the Flamingo collections were at a stage where they could be considered "blood-thirsty" mosquitoes. In contrast, only about 60% of the Big Pine Key females were in this category. Both the frequency and the fecundity of autogenous females were significantly greater at Flamingo.5. The higher engorgement rate for the Big Pine Key population when compared to the Flamingo population can be readily attributed to the differences in the availability of a single host species, the Key deer.6. Our findings support the hypothesis that autogenous females are abundant in some populations of A. taeniorhynchus because hosts are either unavailable or available on a very limited basis.

Leishmania in the chick embryo. 3. Multiplication of L. mexicana and L. braziliensis in the liver.

Abstract Promastigotes of Panamanian strains of Leishmania mexicana and L. braziliensis were inoculated intravenously into 14-day chick embryos. The course of infection was followed by examination of liver impression smears prepared from embryos incubated at 28, 33, and 35°C for 1 hour and 1, 2, and 4 or 6 days post-infection. Parasites of each species declined in numbers rapidly at 35°C. Parasites multiplied more rapidly at 28 than at 33°C, and greater numbers of parasites were observed in the liver after 4 days of incubation at 28°C than after 6 days at 33°C. Multiplication of the two Leishmania species was similar at 28 and 33°C, respectively. Morphologically, L. braziliensis in the liver of chick embryos was more compact and stained more intensely than L. mexicana. Although L. mexicana was generally pale-staining and swollen in appearance, the parasites were viable as demonstrated in cultures initiated with infected liver. Promastigote and amastigote forms were observed in embryos incubated at 28°C, while no flagellum was seen on forms at 33°C.

Malaria parasites of the "Borriguerro" lizard, Ameiva ameiva (Sauria: Teiidae) in Panama.

SYNOPSIS. The teiid lizard Ameiva ameiva praesignis in Panama is parasitized by 2 species of Plasmodium: P. cnemidophori Carini and P. diminutivum sp. n. The Panamanian strain of P. cnemidophori has thick macrogametocytes which are larger than the oval microgametocytes, and schizonts which contain 42–119 nuclei. P. diminutivum is characterized by round to oval gametocytes which are usually smaller than the host cell nucleus; fan‐shaped schizonts with 4–6 nuclei; and prominently vacuolated young stages, with a thick band of chromatin along the periphery of the vacuole.

Colonization of Anopheles Pseudopunctipennis in Panama1

A Panamanian strain of Anopheles pseudopunctipennis was colonized and has been sustained for 40 generations. Immature stages were mass reared applying usual insectary techniques. Average pupal yields have reached over 1000 per day. Adults were maintained in large screened cages and exposed to natural cycles of photoperiod, temperature, and relative humidity. Periodic modifications of these factors facilitated adaptation of the colony.

Behavior of Leishmania in Panamanian phlebotomine sandflies fed on infected animals

Two species of Panamanian sandflies, Lutzomyia sanguinaria and Lu. gomezi, were fed on hamsters infected with various strains of Leishmania. Repeated trials proved that all Panamanian strains of Leishmania braziliensis, whether isolated from man, other mammals, or wild sandflies, produced infections in both sandfly species that were characterized by growth of leptomonad (promastigote) flagellates in the hindgut, especially the “hind triangle,” with or without growth in the midgut. Over 90% of the flies had attached flagellates in the hindgut, and almost half of these had attached flagellates only in the hind triangle. A strain of L. braziliensis from Peruvian espundia reacted similarly in the sandflies. On the other hand, two strains of L. mexicana from Guatemala and British Honduras typically caused midgut infections alone in Lu. sanguinaria and Lu. gomezi. In over 70% of the flies, flagellates were confined to the midgut alone, without even free flagellates in the hindgut. These studies indicate that position of flagellates in the sandfly gut may serve as a reliable taxonomic character for the separation of strains or species of Leishmania.

Fate of Some Culture Flagellates in the Hemocoel of Rhodnius prolixus

The fate of 18 species or strains of culture flagellates was studied following introduction into the hemocoel of Rhodnius prolixus. Trypanosoma rangeli, except for the Panama strain and the rangeli-like strains, multiplied and survived for an indefinite period. T. cruzi and a cruzi-like strain survived for a limited number of days before being killed by the hemocytes. Species of flagellates for which an invertebrate host other than R. prolixus, is known, or for which an invertebrate host is not known, were destroyed rapidly, usually within 24 hr. One exception was the insect flagellate, Crithidia fasciculata, which multiplied and was pathogenic to the bug. It is suggested that this technique might be an aid in separating T. rangeli and T. cruzi from similar and confusing trypanosomes. Several species of Trypanosomatidae are normally parasites of reduviid bugs. The ordinary method by which these bugs acquire infection is by ingestion since all are predacious, living on the blood of insects or higher animals. In some species of reduviid parasites, e.g. Trypanosoma cruzi and T. conorhini, development to the infective stage is completed in the digestive tube in which case transmission to another host is achieved by contamination with the bug's excrement. At least one species, T. rangeli, however, continues development beyond the digestive tube, in the hemocoel, and the infective stage occurs in the salivary glands of the reduviid. Transmission is accomplished when the insect feeds (Tobie, 1964). The intermediate host and the method of transmission of certain trypanosomes are not known. The identity of some species has been questioned because of morphologic similarity to T. cruzi, T. minasense, or T. rangeli and because they were named as new species only by virtue of being found in new hosts (Dunn et al., 1963; Marinkelle, 1966). Survival of parasites in abnormal hosts has attracted some attention but for reasons different from those which stimulated the work reported here. The present studies were undertaken with the idea that the fate of a species in the hemocoel might be an indication of the parasite's tolerance of a host and mode of transmission. T. rangeli is unique in that it invades and multiplies in the hemocoel, but the percentage of Rhodnius prolixus in which the parasite passes through the wall of the Received for publication 1 March 1968. digestive tube is low (Tobie, 1965). It was not expected that abnormal parasites would penetrate the intestinal wall freely. Therefore, to observe the fate of these species in the hemocoel, it was necessary to by-pass the intestinal barrier and initiate the infection in the hemocoel. It appears that this technique may indirectly aid in the separation of certain species of trypanosomes. It is of interest to note that McGhee et al. (1965) observing the fate of six species of Crithidia in several abnormal hosts concluded that their findings, in addition to those of others, indicate that the six isolates were distinct species. MATERIALS AND METHODS The 18 species or strains of Trypanosomatidae used represent three genera, Crithidia (1 species), Leishmania (2 species), and Trypanosoma (9 species, 15 strains). All were grown on diphasic blood agar media. Male Rhodnius prolixus were preferred for these studies because inoculation and dissection were not complicated by the abdomen being filled with eggs. Females were used, however, when the required number of properly fed males was not available. Well fed specimens were selected from a laboratory reared colony, preferably following the first feeding after becoming adults. They were inoculated a week later when they were no longer engorged but yet not starved. At this stage hemolymph was plentiful and usually the puncture wound had a chance to heal before the next feeding. To quiet the bugs for handling they were chilled in a refrigerator at 4 C. Inoculation was then accomplished as in earlier studies (Tobie, 1961) by injecting a minute drop of rich culture material into the hemocoel through the lateral margin of the abdominal segments (the connexivum) with a 1/ ml syringe and a short 27 gauge needle. This was done under the low magnification of a dissecting microscope. Bugs were held, ventral side up, between the tips of a forceps. The needle was

Influence of resistance-factors on the phage types of Salmonella panama.

The resistance to antibiotics which has been increasingly observed in naturally occurringSalmonella panama, is due to an R-factor. A relationship was found between phage pattern and the presence of this R-factor. All strains belonging to phage types A, C and E are sensitive to all antibiotics and are indicated in phage-typing by wild-type phage 47 or host-range mutants of phage 47. All strains belonging to phage types B, D and F possess an R-factor and are indicated by host-modified variants of phage 47. Phage type G, indicated by a host-range mutant, and group Z contain strains with, as well as without an R-factor. Spontaneous drug-sensitive segregants of type B, D and F strains have the phage pattern A, C and E respectively. Conversely, the phage pattern of A, C and E type strains change into B, D and F respectively after infection with the R-factor ofS. panama. The theory can be advanced that type B type A+R-factor, D — C+R-factor and F = E+R-factor. This change in phage type can be considered to be due to the fact that the R-factor exerts restriction and modification of the phage which indicates theS. panama strain without the R-factor. Many of the antibiotic-resistantEscherichia coli strains found in nature possess an R-factor which can be transferred toS. panama in vitro. Relatively few of these R-factors were found to possess also the restriction marker. Thus up to the present the number ofE. coli strains possessing an R-factor which is able to create a dependable combination of phage type and drug resistance inS. panama is relatively small.

Infectivity to mosquitoes of Plasmodium falciparum as related to gametocyte density and duration of infection.

Summary and Conclusions Mosquitoes were fed at all stages of infection on 88 cases of Plasmodium falciparum. Observations were made on the relations of gametocyte densities and length of patency to infectivity. Mosquitoes frequently became infected when fed on gametocyte densities of less than 10 per cmm. of blood, and were infected as late as day 321 of parasite patency in the South Carolina strain, and 410 in the Panama strain. It is concluded that the long enduring parasitemias of these South Carolina and Panama strains of P. falciparum are of considerable epidemiological importance and may be responsible for a large part of the transmission of this species in certain endemic areas.

Susceptibility of Anopheles quadrimaculatus and A. albimanus to domestic and foreign strains of Plasmodium vivax.

SummaryThe relative susceptibility of Anopheles quadrimaculatus and two strains of A. albimanus (Panama and Florida Keys strains) to three strains of Plasmodium vivax was determined. The strains of vivax included a U. S. strain (St. Elizabeth), a New Guinea strain (Chesson), and vivax of Korean origin.In all cases A. quadrimaculatus showed a high degree of susceptibility, while the two strains of albimanus either were completely non-susceptible, as in the Korean vivax, or became infected only occasionally and at a very low rate.The infectivity of Korean vivax to A. quadrimaculatus, and transmission through that species, confirms the possibility of establishment of malaria from that area in this country.

The duration in the human host of infections with a Panama strain of Plasmodium falciparum.

Summary and ConclusionsIn a Panama strain of Plasmodium falciparum 23 inadequately treated infections persisted for an average of 279.5 ± 19.9 days, with a range in duration from 114 to 503 days. Four cases persisted for more than a year. The initial period of continuous parasitemias in 37 cases persisted for an average of 115.7 ± 7.5 days. This was followed in 23 cases by a period of terminal intermittent parasitemias with a mean duration of 168 ± 19.0 days. There was little difference between blood and sporozoite induced infections where duration of the infection was concerned.The results reported extend to a tropical strain the findings of Eyles and Young (1951) on the duration of a temperate zone strain of P. falciparum. The application of these findings to certain field conditions is discussed.The Panama strain of falciparum apparently is somewhat more virulent than the United States strain. Although the maximum parasite densities were similar in the two strains, the Panama strain was nearly double the U. S. strain in the length of initial clinical episode, number of clinical episodes and total hours of fever. Other criteria suggestive of strain difference are the significantly longer duration of terminal intermittent parasitemias in the Panama strain, the absence of cross-immunity between the two strains, and differences in gametocyte morphology.

Exo-erythrocytic stages of Plasmodium falciparum.

Summary and ConclusionsLiver tissue was taken from 14 patients after massive sporozoite inoculations with a Panama strain of Plasmodium falciparum. The tissue was fixed in Carnoy's fluid, serially sectioned, and stained with a colophonium-Giemsa method.Exo-erythrocytic parasites were found in the material derived from the patient receiving the heaviest inoculations. This patient had been inoculated on four successive days with a total of 8,516 mosquito bites and 1,403 salivary glands intravenously. The mosquitoes used averaged 86.8 per cent infected. Biopsy was done at laparotomy three to six days after inoculation. A total of about 125 parasites was found. The characteristics of these parasites indicate that they are part of the exo-erythrocytic phase of malaria. They are similar to those found by Shortt and his associates for this species of malaria.

Cross-Immune Reactions between Panamanian Strains of Q Fever and Endemic Typhus

Summary Guinea-pigs recovered from an infection with the SM strain of murine typhus showed a partial immunity against the Panamanian JD strain of Q fever as indicated by prolongation of the incubation period and shortening of the febrile period. In reverse cross-immunity experiments, guinea-pigs immune to the JD strain of Q fever showed a variable febrile reaction and consistent suppression or modification of the testicular reaction on inoculation with murine typhus rickettsia. Complement-fixation tests, employing immune guinea-pig serums and yolk sac antigens, showed no significant cross-reactions.

Ineffectiveness of Certain Pentavalent Arsenicals Used Orally in T. hippicum Infected Guinea Pigs

Kolmer has reported that “stovarsol and treparsol in doses of approximately 0.030 to 0.040 gm. per kilo of weight by oral administration for 3 to 10 days were effective in preventing trypanosomiasis of rats infected with T. equiperdium. Atoxyl was slightly more effective, as doses of 0.020 to 0.030 gm. per kilo per day (orally)…. for 5 to 10 days prevented infection.” Tryparsa-mide and “Bayer 205” or “Germanin” were ineffective when given orally to infected animals. He further states that when treatment was started 24 hours after infection the arsenicals were more active than when given before or at the time the infection was induced. Cooper originally demonstrated this phenomenon using tryparsa-mide, etharsanol and “arsenoxide”. The treatment of equine trypanosomiasis (T. hippicum) has been unsatisfactory with the common trypanocides because horses require large amounts of expensive drugs given intravenously. Dr. Herbert Clark of Panama has been partially successful with approximately 5 times the human dose of tryparsamide or “Bayer 205” combined with tartar emetic, given at weekly intervals over relatively long periods. Certain disadvantages are: first, that the cost of medication may exceed the value of the treated animal, secondly, that embolic phenomena occur with intravenous administration, thirdly, that neither prophylactic therapy nor treatment of infected animals is always successful. A more satisfactory form of therapy is needed, that is, a cheap drug that can be given by mouth without toxicity in prophylactic or therapeutic doses. Kolmer's report suggested the possibility of a successful approach to the problem from the standpoint of oral effectiveness with certain arsenical trypanocides. Guinea pigs infected with the Panamanian strain of T. hippicum were treated with atoxyl, acetarsone (“stovarsol'), and carbarsone given orally. Standard intraperitoneal injections were made into normal healthy guinea pigs using 0.3 cc. of infected guinea pig blood with an equivalent amount of sterile physiological saline.