Taxonomic status and re-description of Plasmodium relictum (Grassi et Feletti, 1891), Plasmodium maior Raffaele, 1931, and description of P. bigueti n. sp. in sparrows.

The first accurate re-description of Plasmodium relictum (Grassi et Feletti, 1891) in its type host was provided by Raffaele in 1931, and the name relictum should thus refer to this work. In his article, Raffaele noted the presence of an associated but distinct species, P. maior. The work of Raffaele has since remained overlooked, and the taxon relictum has been applied rather loosely to parasites found in numerous birds of diverse geographic origin. Examination of Passer domesticus specimens collected in France has confirmed the presence of the two species above, and further revealed that two other species can also be found in these birds. P. bigueti n. sp. is described here, whereas the other Plasmodium sp. was not found in sufficient numbers to allow characterisation.

Variation in murid Plasmodium desequestration and its modulation by stress and pentoxifylline.

Changes in the parasitaemia and the characteristics of parasitic infection for three species of rodent Plasmodium (P. chabaudi chabaudi, P. vinckei petteri and P. yoelii yoelii) were investigated under conditions of stress and after treatment with pentoxifylline (POF), a drug that increases red blood cell deformability and causes peripheral vasodilatation. The results indicated that under stress, late parasite stages became less abundant in the tail blood of mice. These changes might be the consequence of parasite sequestration. Attempts to assess sequestration intensity were made by measuring the release rate (RR) of late stages for 10,000 red blood cells. The RR is given by the product of the parasitaemia (P) by the percentage of old trophozoites (OT) and schizonts (S) in the peripheral blood: RR = P(%OT + %S) . With all three species, RR decreased considerably within 5 min following the manipulation of the mice. Injections of POF had the opposite effect. POF had a protective effect against infection by P.v. petteri, causing a delay of 48 h in the development of infection and a higher survival rate in treated mice.

New Pudicinae (Trichostrongylina, Heligmosomoidea) coparasites of Proechimys longicaudatus (Caviomorpha) from Bolivia. I--Description of Pudica ginsburgi n. sp. and Heligmostrongylus chiarae n. sp.

Two new Pudicinae (Trichostrongylina, Heligmosomoidea, Heligmonellidae) coparasites of Proechimys longicaudatus (Caviomorph rodent) from Bolivia are described: Pudica ginsburgi n. sp. is differentiated from all the other species of the genus by the great length of the spicules and of the vestibule and by a different ratio of the length of the spicules on the length of the body. Heligmostrongylus chiarae n. sp. has very developed rays 4, strongly divergent from rays 5 as occurs in three other species, H. almeidai (Durette-Desset & Tcheprakoff, 1969), a parasite of Trichomys apereoides (= Cercomys cunicularius) from Brazil, H. squamastrongylus (Travassos, 1937), a parasite of Proechimys oris from Brazil and H. proechimysi Durette-Desset, 1970, a parasite of Proechimys semispinosus from Columbia. The specimens from Bolivia are differentiated from the three species by the division of the dorsal ray (anterior half versus posterior half) and by a different ratio of the length of the spicules on the length of the body.

Short-term effect of chloroquine on the infectivity of Plasmodium chabaudi gametocytes.

The short-term enhancing effect of chloroquine on gametocyte infectivity was investigated with Plasmodium chabaudi chabaudi, a synchronous parasite which is highly sensitive to chloroquine. In comparison with control groups, oocyst numbers increased in mosquitoes fed on mice 12 hours after the injection of 5 mg/kg chloroquine (180% of controls) although it was not statistically significant. No effect was seen with 1 mg/kg chloroquine. The authors interpretation is that chloroquine impaired the schizogony, thus reducing also the release of toxic material of parasite origin which blocks gametocytes infectivity. Results of similar experiments with other rodent species of Plasmodium are compared and discussed in relation with the chronobiological characteristics of these parasites.

The effects of subcurative doses of chloroquine on Plasmodium vinckei petteri gametocytes and on their infectivity to mosquitoes.

The effects of subcurative doses of chloroquine on rodent and human Plasmodium transmission to the mosquito have been studied by several authors who showed a short-term (12 h) enhancement of gametocyte infectivity by the drug, restricted to chloroquine-resistant strains, and a long term (4-6 days) enhancement of gametocytogenesis of chloroquine-sensitive strains of Plasmodium chabaudi. We investigated both short- and long-term effects of chloroquine on Plasmodium vinckei petteri, a chloroquine-sensitive rodent Plasmodium strain. Chloroquine treatment reduced the index of gametocytogenesis to 73% (5 mg/kg) and 55% (2.5 mg/kg) of controls, on day 6 post-infection (p.i.). The reduction was statistically significant with 5 mg/kg chloroquine. However, the reduction of gametocyte numbers did not affect the transmission capabilities of the strain. Our experiments showed that doses of 1 mg/kg chloroquine had no effect on the oocyst counts, 12 h post-administration to mice. A statistically non-significant 61% reduction of oocyst numbers was observed in mosquitoes fed on mice treated with 5 mg/kg chloroquine. The effect of 5 mg/kg chloroquine administration on the infectivity of gametocytes to mosquitoes fed 1 h post-treatment was also investigated. An overall 41% reduction of oocyst numbers was observed. This immediate effect was statistically significant in 73% of the mice. These results are consistent with the hypothesis that the short-term enhancing effect of chloroquine on transmission is restricted to the drug-resistant strains of Plasmodium.

A cladistic analysis of the Trichostrongyloidea (Nematoda).

A morphologically based cladistic analysis of 40 genera included within the Trichostrongyloidea (Amidostomatidae, Dromaeostrongylidae and Trichostrongylidae) is proposed. Two genera were used as outgroups, one from the Strongylina and the other from the Ancylostomatina. Seven genera do not appear in the matrix because some significant morphological characters remain unknown for these genera. Nonetheless, except for Moguranema which is excluded as incertae sedis, a likely systematic position could be assigned to them based on the morphological characters that are known. The classification which best fits the consensus tree is composed of three families. In adding the genera not included in the tree, we obtain: (i) Trichostrongylidae with three sub-families, Amidostomatinae (four genera), Filarinematinae (three genera) and Trichostrongylinae (five genera); (ii) Haemonchidae with two sub-families: Ostertagiinae (eight genera) and Haemonchinae (five genera); (iii) Cooperiidae with three sub-families: Libyostrongylinae (five genera), Obeliscoidinae n. subfam. (five genera) and Cooperiinae (ten genera). Dromaeostrongylus and Ortleppstrongylus, whose females have a caudal spine, are excluded from the Trichostrongyloidea and are placed in the Molineoidea. The hypotheses relating to the evolutionary history of the Trichostrongyloidea are: the origin of the superfamily could have occurred during the upper Cretaceous period. The two most ancient sub-families (Amidostomatinae and Filarinematinae) would be of Gwondwanan origin and evolved during the Paleocene period within Neotropical aquatic birds and within the Australian marsupials. The Trichostrongylinae would have arisen during the Eocene period within birds and then adapted to diverse archaic mammals in the Neotropical region on one hand and in the Nearctic region, on the other hand and lastly adapted to the Lagomorpha and subsequently to the Ruminantia. In both families originating from the Trichostrongylidae, the adaptation to the Lagomorpha may have taken place during the Oligocene but in a different way. In the Haemonchidae, the Ostertagiinae may have passed directly from the Neartic region to Europe. In the Cooperiidae, the adaptation to Lagomorpha may have occurred either within the Libyostrongylinae which may have remained in the Ethiopian region since the Paleocene, or, more likely, by the passage of the Obeliscoidinae from the Nearctic region to the Asian, through the Bering strait. In all cases, the adaptation of the Trichostrongyloidea of Lagomorpha to Ruminants apparently took place during the Miocene, mainly in the Palearctic and the Ethiopian regions.

Final stage of maturation of the erythrocytic schizonts of rodent Plasmodium in the lungs.

Schizonts of all rodent Plasmodium studied (Plasmodium yoelii, P. chabaudi, P. vinckei) show a characteristic morphology when they are completely mature: rounded or slightly elongate merozoites, completely detached from the pigment mass. At this stage, they are localized principally in the spleen and the lungs but, in impression smears of these organs they show two different aspects. In the spleen, schizonts are either inside the host erythrocyte or extraglobular but still close to a pigment mass; free merozoites are rare. In the lungs, on the contrary, merozoites are often free and dispersed; electron microscopy showed them to lie against the endothelium. Work by physiologists has shown the blood circulation in the alveoli to be much slowed down. Free merozoites, lined against the endothelium of relatively rigid capillaries, are in the best possible conditions to make contact with the intact red blood cells. Lungs appear to be the privileged site for the invasion of erythrocytes by the merozoites.

Survival of rodent malaria merozoites in the lymphatic network: potential role in chronicity of the infection.

Experiments performed during the last few years, lead us to hypothesise the existence of latent asexual forms of murine Plasmodium. In the present report we examined the organs of infected animals and describe novel structures, which we call merophores, containing merozoites which have resisted lysis seen with other asexual stage parasites. We propose that these merozoites represent a latent form of the parasite. Merophores were also found in the lymphatic circulation, and were demonstrated by subinoculation to have retained their viability. Depending on the parasite species two types of merophores were observed. For P. yoelii nigeriensis merophore sacks, with the latent merozoites found inside vesicles, were usually observed. Merophore leucocytes, where latent merozoites dispersed in the cytoplasm of macrophages or neutrophils, were solely seen with P. vinckei petteri. Both structures were seen in P. chabaudi chabaudi infections. Merophores were found in lymph nodes of rodents after the asexual parasitaemia had apparently subsided. They were formed soon after schizogony, principally in the spleen, either by pitting or by macrophage phagocytosis. Merophore numbers appeared to be proportional to the number of maturing schizonts. We propose that merophore formation and their circulation in the lymphatics play an important role in the pattern of recrudescences and chronicity of rodent malaria infections. It is further suggested that the lymphatic network, a privileged pathway for many parasites, might play a similar role in human malaria infections.

Development of irreversible lesions in the brain, heart and kidney following acute and chronic murine malaria infection.

Irreversible pathological lesions were noted in the organs of mice infected with 1 of 3 rodent malaria species: Plasmodium chabaudi chabaudi, P. vinckei petteri and P. yoelii nigeriensis at different times during the course of the primary parasitaemia and long after microscopical clearance of the parasites. Moreover, similar lesions were also obtained when parasite levels were kept below 1% by subcurative drug treatment. The frequency and severity of the lesions correlated with the duration of the infection. Accumulation of tissue damage during chronic low-grade malaria infections has implications for the design of control measures.

Chronosexuality of Plasmodium species of Central African Muridae.

A host harbouring many parasite species of the same genus is a phenomenon frequently observed in numerous parasitic infections. This is the case for the Plasmodium parasites of Muridae in Central Africa, where three different parasite species are found in the same rodent host species. It is highly likely that these three Plasmodium species are transmitted simultaneously by the same vector. We and others have shown that the maturation periods of the various asexual and sexual stages in the rodent, differ amongst the three parasites. In this article we propose that these differences are the product of complex adaptations which result, for all three Plasmodium species, in a maximum peak of infectivity to the insect vector occurring around 3 a.m., the period of highest activity of the nocturnal host rodent.

Tapironema coronatum n. gen., n. sp. (Trichostrongyloidea-Cooperiidae-Obeliscoidinae), a parasite of Holochilus brasiliensis and Tapirus terrestris.

In this paper we provide a description of Tapironema coronatum n. gen. n. sp. (Trichostrongyloidea, Obeliscoidinae) from the cricetid Holochilus brasiliensis or "water rat" in Argentina (Type material) and from Tapirus terrestris in French Guyana (voucher material in poor condition). The new genus is characterized by a corona radiata, an oesophageal tooth, a bilaterally synlophe with about 73 (male), 122 (female) cuticular ridges, a caudal bursa pattern 2-1-2 with rays 5 and 6 parallel and close together and rays 5 longer than rays 3. The most closely related genus is the monospecific Teporingonema Harris, 1985, from a Mexican lagomorph, Romerolagus. The cephalic extremity of this parasite is redescribed after the type-material. The systematic position of Teporingonema amongst the Obeliscoidinae is defined and the hypotheses concerning the origin of this sub family are provided.

Enhanced gametocyte formation by Plasmodium chabaudi in immature erythrocytes: pattern of production, sequestration, and infectivity to mosquitoes.

The objective of this study was to investigate the chronobiology and infectivity of the gametocytes of Plasmodium chabaudi chabaudi. In order to increase the production of gametocytes, mice were treated with phenylhydrazine to induce a hyper-reticulocytosis. The authors observed an important stimulation of gametocytogenesis. Gametocytes were seen as soon as the second day postinoculation and were produced periodically at each schizogony, every 24 hr. The gametocytic developmental cycle lasted 60 hr and consisted of 4 successive stages: stage 0 at 36 hr, from merozoite invasion, stage I at 42 hr, stage II at 48 hr, and stage III at 54 hr. An important fraction of stage II was sequestered in small peripheral capillaries. The numbers of oocysts in the mosquitoes fed on phenylhydrazine-treated mice were larger than in controls. When mosquitoes were fed at different times of the day, circadian differences in the oocyst counts were not statistically significant. However, stage II was considered to be probably the most infective stage because, like the infective gametocyte stage of other species of murine malaria, it is sequestered in the peripheral capillaries. In contrast with Plasmodium vinckei, there is no peak of infectivity at the time of sequestration of the infective stage; this is probably due to the inhibitory effect of the schizogony occurring at this time.

Synchronized Plasmodium yoelii yoelii: pattern of gametocyte production, sequestration and infectivity.

The chronobiology of the gametocytes of P. yoelii was studied in Percoll-glucose synchronized infection in the mouse. The gametocyte developmental cycle consisted of 4 successive stages: stage 0 maturation took 27 hours from merozoite invasion, stage 0 to stage 1 lasted 6 hours, stage I to stage II and stage II to stage III lasted 3 hours each. Stage 0 gametocytes were found to sequester in small peripheral capillaries, and the number of oocysts in mosquitoes was related to the number of stage 0 gametocytes ingested.

The gametocytes of Plasmodium vinckei petteri, their morphological stages, periodicity and infectivity.

Gametocyte production by P. vinckei petteri was cyclic, occurring at each schizogony every 24 h. They matured in 27 h from merozoite to type 0 microgametocyte, in 3 h from type 0 to type I, 6 h from type I to type II and 3 h from type II to type III. Transmission experiments showed that the time of maximum infectivity was midday when mice were inoculated at midnight, and midnight when mice were inoculated at midday. In all instances, maximum infectivity coincided with a peak in intensity by type II microgametocytes, a relationship confirmed by multiple correspondence analysis. The proportion of type II microgametocytes was higher in the mosquitoes blood meal than in smears of tail blood of mice, suggesting a sequestration phenomenon with this stage.

The erythrocytic schizogony of two synchronized strains of plasmodium berghei, NK65 and ANKA, in normocytes and reticulocytes.

By a modified Percoll-glucose centrifugation technique the rings and young trophozoites of two strains of Plasmodium berghei, NK65 and ANKA, were separated from the other erythrocytic stages and inoculated into mice. The subsequent infection was followed for ANKA in normal mice and for NK65 in normal mice and in mice with high-grade reticulocytosis induced by injections of phenylhydrazine. The duration of the erythrocytic schizogony of the NK65 strain was shown to be independent of the age of the host cell, and the hour of inoculation did not influence the cycle of the ANKA strain.

A new zoonosis of the cerebrospinal fluid of man probably caused by Meningonema peruzzii, a filaria of the central nervous system of Cercopithecidae.

A female fourth stage larva of Meningonema, probably of M. peruzzii Orihel et Esslinger, 1973, was recovered in Cameroon, from the cerebrospinal fluid of a patient harbouring Loa loa, but without any neurological signs. This observation is the first human case of Meningonema (Filarioidea Splendidofilariinae) which usually parasitizes the central nervous system of African Cercopithecinae. However, as indicated by Orihel and Esslinger, it seems probable that the perstans-like microfilariae described in cases of cerebral filariasis in Zimbabwe belonged to the same species.

Plasmodium vinckei vinckei and P. yoelii nigeriensis: pattern of gametocyte production and development.

The morphological evolution and the periodicity of the gametocytes of two rodent malaria species were studied in the white mouse. Experiments with Plasmodium vinckei vinckei, a highly synchronous species, showed that the production of the sexual stages was periodic and was set by the specific rhythm of the asexual stages, i.e. the time of inoculation and the duration of the cycle in the blood. The duration of gametocytogenesis from merozoite to stage 0 was approximately 30 hours, and from stage 0 to stage III, 6 hours. Plasmodium yoelii nigeriensis which normally develops asynchronously in the blood was synchronized by a Percoll-glucose gradient fractionation. Although the duration of the asexual cycle was 18 hours, gametocytogenesis from merozoite to stage 0 lasted 24 hours and 12 hours from stage 0 to stage III. Some degree of sequestration was observed in the young gametocytes.

The adjustment of the schizogonic cycle of Plasmodium chabaudi chabaudi in the blood to the circadian rhythm of the host.

Experiments were performed with P. chabaudi chabaudi to investigate the relationship between the development of the parasite and the circadian rhythm of the host. Blood was taken from a donor mouse at 10.00 hours, when it contained mainly young stages and inoculated to receptor mice, either immediately or after B hours at +4 degrees C. The inoculum was diluted in order to obtain a more or less extended prepatent period. Thus, by using successively the different mice, parasitemias could be followed during 12 days before the crisis. When parasitemias reached 1%, from day 1 (D1) to D7, depending on the dilution, the parasitic patterns were studied every 6 hours during 2 or 3 days. In mice inoculated at 10.00 hours the rhythm remained unmodified. In mice inoculated at 18.00 hours the infection was at first synchronous (from D1 to D4) but the schizogony occurred between 06.00 and 12.00 hours instead of midnight. From day 4 to day 7 the infection became asynchronous. At day 10 the normal rhythm was resumed and the schizogony occurred around midnight.

The evolutionary expansion of the Spirurida.

The possible origins of the 12 superfamilies of the Spirurida are considered, based on comparative morphology, host and geographic distributions. The available evidence suggests a complex origin of these nematodes, some families being derived from the Seuratoidea, and others from the Cosmocercoidea (Ascaridida). The spirurid radiation is an old one and seems to have occurred primarily in the Secondary or early Tertiary eras. Since then, expansion has occurred with host capture as a prominent mechanism. The Dracunculoidea Procamallanidae and Camallanidae are probably derived from the Chitwoodchabaudiidae and the Rictularioidea from the Schneidernematidae. The Seuratidae may have given rise to the Gnathostomatoidea, the Physalopteroidea, the Thelazioidea, the Habronematoidea, the Spiruroidea and the Acuarioidea. The filarioid nematodes appear to have several origins with the Diplotriaenoidea derived from the Spiruroidea, while constituents of the Aproctoidea derived from the Cystidicolinae, the Seuratoidea and the Spiruroidea. The Filarioidea are thought to have arisen from the Spiruroidea and the Thelazioidea. The evolution of tissue parasitism as a secondary phenomenon is considered in various groups.