Scolex Morphology of Proteocephalid Cestodes Parasites of Neotropical Freshwater Fishes

The morphology of the scolices and metascolices of 29 proteocephalid species, parasites of freshwater fishes from Brazil was compared by using scanning electron microscope, light and laser microscopy. The following species were evaluated: Proteocephalus vazzolerae, P. piramutab, Robertiella paranaensis, Travassiella avitellina, Monticellia loyolai, M. spinulifera, M. belavistensis, Houssayela sudobim, Zygobothrium megacephalum, Gibsoniela mandube, Cangatiella arandasi, Nomimoscolex sudobim, N. lopesi, N. admonticellia, N. piraeeba, N. pirarara, Harriscolex kaparari, Crepidobothrium eirasi, Spatulifer rugosa, Megathylacus brooksi, Choanoscolex abscisus, Amphoteromorphus peniculus, A. piraeeba, Paramonticellia itaipuensis, Peltidocotyle rugosa, Othinoscolex lenha, Rudolphiella rugata, R. piranabu, Jauella glandicephalus. Some features as overall shape of scolex, suckers, apical sucker, frontal glands and several kinds of metascolex were analyzed. The taxonomic importance of scolex and metascolex is discussed.

A new Culicoides from The Amazonian Region, Brazil (Diptera: Ceratopogonidae)

A new Neotropical species of biting midge Culicoides (Haematomyidium), C. kampa Felippe-Bauer, Veras & Castellon, is described and illustrated based on female specimens from the Amazonian Region.

Nematodes of elasmobranch fishes from the southern coast of Brazil

New records for nematode species recovered from elasmobranch fishes in Brazil are established and new systematical arrangements proposed. Parascarophis sphyrnae Campana-Rouget, 1955 from the spiral valve of Sphyrna zygaena is referred for the first time in South America as a new host record. Procamallanus (S.) pereirai Annereaux, 1946, from the spiral valve of Raja castelnaui is reported parasitizing an elasmobranch host. Nematode larvae of the genera Anisakis, Contracaecum, Pseudoterranova and Raphidascaris are listed from the stomach and spiral valves of several hosts. Anisakidae larvae previously referred in Brazil in the genus Phocanema should be reallocated in Pseudoterranova. Nematodes of the genera Anisakis, Contracaecum, Pseudoterranova and Raphidascaris are reported for the first time parasitizing elasmobranchs in Brazil.

First report of Lutzomyia (Nyssomyia) umbratilis Ward & Frahia, 1977 outside of Amazonian Region, in Recife, State of Pernambuco, Brazil (Diptera: Psychodidae: Phlebotominae)

Lutzomyia umbratilis, a known vector of Leishmania guyanensis in the north of Amazon basin, has been exclusively found in the Amazonian region. Here we report for the first time the occurrence of this species in northeastern Brazil. The epidemiological importance of the occurrence of this species in the Atlantic Forest is commented.

Digenea and acanthocephala of elasmobranch fishes from the southern coast of Brazil

New records for helminth species recovered from elasmobranch fishes in Brazil are established. Digenean and acanthocephalan parasites of elasmobranch fishes are reported from the southern coast of Brazil: Otodistomum veliporum (Creplin, 1837) Stafford, 1904 (Digenea: Azygiidae) in the stomach and spiral valve of Dipturus trachydermus and in the spiral valve of Squatina sp. Cystacanths and juveniles of the acanthocephalans Corynosoma australe Johnston, 1937 and Corynosoma sp., in the spiral valve of Squatina sp., Galeorhinus galeus and Hexanchus griseus and in the stomach of Squalus megalops; a juvenile of Gorgorhynchus sp., in the spiral valve of Sphyrna zygaena. Dipturus trachydermus and Squatina sp. are new host records for O. veliporum. Digeneans and acanthocephalans are reported for the first time parasitizing elasmobranch fishes in Brazil.

A Rural Community in a Brazilian Western Amazonian Region: Some Demographic and Epidemiological Patterns

Some demographic and epidemiological patterns of the rural population of Monte Negro, locality situated in the State of Rondônia (Brazil), Western Amazonia, are described based on a sample of 924 randomly selected individuals, approximately 10% of the whole population. The main features of this sample are (1) the illiteracy rates in the parental generation were 23% for fathers and 20% for mothers. Among children, this figure dropped to 6%; (2) housing in Monte Negro is characterized by being constructed with wood (92%), and also a floor (75%). Nevertheless, only 32% of these houses had electric energy; (3) the mean ages for the parental generation were 41.9 for males and 36.3 for females. These values for the offspring generation were 12.2 and 10.5, respectively; (4) the sex-ratio of the offspring generation was 1.32;(5) the bioassay of kinship was estimated as .033 for this long range migrant population; (6) the prevalence of some macrophage dependent infectious disease was conspicuously high; (7) the reported number of malarial episodes among males and females was statistically different, suggesting that malaria may be, in part, a "professional" disease; (8) the prevalence of serum-positive reactions against B-hepatitis is distressing. It has a strong age dependence and reaches 74% among adult males. Conversely, signs of active infection (AgHbs) rises to 16% among children.

The association of genetic markers and malaria infection in the Brazilian Western Amazonian region

Almost all individuals (182) belonging to an Amazonian riverine population (Portuchuelo, RO, Brazil) were investigated for ascertaining data on epidemiological aspects of malaria. Thirteen genetic blood polymorphisms were investigated (ABO, MNSs, Rh, Kell, and Duffy systems, haptoglobins, hemoglobins, and the enzymes glucose-6-phosphate dehydrogenase, glyoxalase, phosphoglucomutase, carbonic anhydrase, red cell acid phosphatase, and esterase D). The results indicated that the Duffy system is associated with susceptibility to malaria, as observed in other endemic areas. Moreover, suggestions also arose indicating that the EsD and Rh loci may be significantly associated with resistance to malaria. If statistical type II errors and sample stratification could be ruled out, hypotheses on the existence of a causal mechanism or an unknown closely linked locus involved in susceptibility to malaria infection may explain the present findings.

Two new Culicoides of the paraensis species group (Diptera:Ceratopogonidae) from the Amazonian region of Peru

Two new species of the Culicoides paraensis species group, C. diversus Felippe-Bauer and C. peruvianus Felippe-Bauer, are described and illustrated based on female specimens from Amazonian region of Peru. A systematic key, table with numerical characters of females, and distribution of species of the C. paraensis group are given.

Haematozoan parasites of the lizard Ameiva ameiva (Teiidae) from Amazonian Brazil: a preliminary note

Three different haematozoan parasites are described in the blood of the teiid lizard Ameiva ameiva Linn. from North Brazil: one in the monocytes and the other two in erythrocytes. The leucocytic parasite is probably a species of Lainsonia Landau, 1973 (Lankesterellidae) as suggested by the presence of sporogonic stages in the internal organs, morphology of the blood forms (sporozoites), and their survival and accumulation in macrophages of the liver. One of the erythrocytic parasites produces encapsulated, stain-resistant forms in the peripheral blood, very similar to gametocytes of Hemolivia Petit et al., 1990. The other is morphologically very different and characteristically adheres to the host-cell nucleus. None of the parasites underwent development in the mosquitoes Culex quinquefasciatus and Aedes aegypti and their behaviour in other haematophagous hosts is under investigation. Mixed infections of the parasites commonly occur and this often creates difficulties in relating the tissue stages in the internal organs to the forms seen in the blood. Concomitant infections with a Plasmodium tropiduri-like malaria parasite were seen and were sometimes extremely heavy.

Taxonomic reports of Otobothrioidea (Eucestoda, Trypanorhyncha) from elasmobranch fishes of the southern coast off Brazil

Specimens of elasmobranch fishes, captured in the states of Paraná and Santa Catarina, of the southern coast off Brazil, represented by three families, four genera, and four species, were parasitized with otobothrioid trypanorhynch cestodes: Heptranchias perlo (Bonnaterre, 1788), Squalus sp. and Carcharhinus signatus (Poey, 1868) were parasitized with Progrillotia dollfusi Carvajal & Rego,1987; Prionace glauca (Linnaeus, 1758) with Molicola horridus (Goodsir, 1841) Dollfus, 1942. Details of internal morphology and/or scolex and/or proglottids surface ultrastructure, that expanded the description of M. horridus, through observations with lightfield, and/or scanning eletronic microscopy, are provided. The known geographical distribution for the species M. horridus is enlarged. P. dollfusi is reported for the first time in elasmobranchs.

Clinical and immunopathological spectrum of American cutaneous leishmaniasis with special reference to the disease in Amazonian Brazil: a review

The wide variety of Leishmania species responsible for human American cutaneous leishmaniasis combined with the immune mechanisms of the host results in a large spectrum of clinical, histopathological, and immunopathological manifestations. At the middle of this spectrum are the most frequent cases of localized cutaneous leishmaniasis (LCL) caused by members of the subgenera Leishmania and Viannia, which respond well to conventional therapy. The two pathogenicity extremes of the spectrum generally recognized are represented at the hypersensitivity pole by mucocutaneous leishmaniasis (MCL) and at the hyposensitivity pole by anergic diffuse cutaneous leishmaniasis (ADCL). Following the present study on the clinical, histopathological and immunopathological features of cutaneous leishmaniasis in Amazonian Brazil, we propose the use of the term "borderline disseminated cutaneous leishmaniasis" for the disseminated form of the disease, due to parasites of the subgenera Leishmania and Viannia, which might be regarded as intermediate between LCL and the extreme pathogenicity poles MCL and ADCL.

Cross-sectional study defines difference in malaria morbidity in two Yanomami communities on Amazonian boundary between Brazil and Venezuela

It is well established that immunity to malaria is short-lived and is maintained by the continuous contact with the parasite. We now show that the stable transmission of malaria in Yanomami Amerindian communities maintains a degree of immunity in the exposed population capable to reduce prevalence and morbidity of malaria. We examined 508 Yanomami Amerindians living along Orinoco (407) and Mucajaí (101) rivers, on the Venezuelan and Brazilian Amazon region, respectively. At Orinoco villages, malaria was hyperendemic and presented stable transmission, while at Mucajaí villages it was mesoendemic and showed unstable transmission. The frequency of Plasmodium vivax and P. falciparum was roughly comparable in Venezuelan and Brazilian communities. Malaria presented different profiles at Orinoco and Mucajaí villages. In the former communities, malaria showed a lower prevalence (16% x 40.6%), particularly among those over 10 years old (5.2% x 34.8%), a higher frequency of asymptomatic cases (38.5% x 4.9%), and a lower frequency of cases of severe malaria (9.2% x 36.5%). Orinoco villagers also showed a higher reactivity of the immune system, measured by the frequency of splenomegaly (72.4% x 29.7%) and by the splenic index (71.4% over level 1 x 28.6), and higher prevalence (91.1% x 72.1%) and mean titer (1243 x 62) of antiplasmodial IgG antibodies, as well as a higher prevalence (77.4% x 24.7%) and mean titer (120 x 35) of antiplasmodial IgM antibodies. Our findings show that in isolated Yanomami communities the stability of malaria transmission, and the consequent continuous activation of the immune system of the exposed population, leads to the reduction of malaria prevalence and morbidity.

Blood and intestinal parasites of squirrels (Rodentia: Sciuridae) in Amazonian Brazil

We report the result of an examination for blood and intestinal protozoa in 12 specimens of the red squirrel Sciurus spadiceus (Rodentia: Sciuridae) from Birroque, municipality of Plácido de Castro, state of Acre, Brazil. No parasites were detected in thin, Giemsa-stained blood films of the animals, but culture of the blood of three in Difco B45 medium blood-agar slants gave rise to isolates of epimastigotes. Inoculation of one isolate into laboratory mice resulted in the appearance of Trypanosoma cruzi-like trypomastigotes in their peripheral blood, and the other two isolates gave rise to transient infections with a T. lewisi-like parasite in inoculated mice and hamsters. The failure of the latter parasite to develop in the triatomine bug Rhodnius robustus suggests that it is probably not T. rangeli. This appears to be the first record of a T. lewisi-like trypanosome in neotropical squirrels. Oocysts of an Eimeria sp., were detected in the faeces of 10 animals (83.3%). The parasite develops in the epithelial cells of the intestine, where it may cause severe damage and sometimes results in death of the animal. No oocysts were detected in bile.

The Genus Cyclospora (Apicomplexa: Eimeriidae), with a description of Cyclospora schneideri n.sp. in the snake Anilius scytale scytale (Aniliidae) from Amazonian Brazil: a review

A review is made of the recorded species of the coccidian genus Cyclospora and major events leading up to the discovery of C. cayetanensis, which is responsible for serious outbreaks of diarrhoea in man and is one of the aetiological agents of "traveller's diarrhoea". Humans appear to be the specific hosts, with the entire life-cycle in the intestine: to date there is no convincing evidence that the disease is a zoonosis. A description is given of oocysts and endogenous stages of C. schneideri n.sp., in the snake Anilius scytale scytale. Sporulation is exogenous and completed after about one week at 24-26º. Mature oocysts 19.8 × 16.6 (15.1 × 13.8-25.7 × 20.1), shape-index 1.2 (1.0-1.3): no oocyst residuum or polar bodies. Oocyst wall a single colourless, smooth layer with no micropyle: it is rapidly deformed or broken. Sporocysts 13.6 × 9.4 (11.3 × 8.3-15.1 × 9.9), shape-index 1.4 (1.2-1.5) with an inconspicuous Stieda body. Sporozoites 11-13 × 2.5-3. Endogenous stages are intracytoplasmic in the epithelial cells of the small intestine and with the characters of the Eimeriorina.

Myxobolus insignis sp. n. (Myxozoa, Myxosporea, Myxobolidae), a parasite of the Amazonian teleost fish Semaprochilodus insignis (Osteichthyes, Prochilodontidae)

A new myxosporean species is described from the fish Semaprochilodus insignis captured from the Amazon River, near Manaus. Myxobolus insignis sp. n. was located in the gills of the host forming plasmodia inside the secondary gill lamellae. The spores had a thick wall (1.5-2 µm) all around their body, and the valves were symmetrical and smooth. The spores were a little longer than wide, with rounded extremities, in frontal view, and oval in lateral view. They were 14.5 (14-15) µm long by 11.3 (11-12) µm wide and 7.8 (7-8) µm thick. Some spores showed the presence of a triangular thickening of the internal face of the wall near the posterior end of the polar capsules. This thickening could occur in one of the sides of the spore or in both sides. The polar capsules were large and equal in size surpassing the midlength of the spore. They were oval with the posterior extremity rounded, and converging anteriorly with tapered ends. They were 7.6 (7-8) µm long by 4.2 (3-5) µm wide, and the polar filament formed 6 coils slightly obliquely to the axis of the polar capsule. An intercapsular appendix was present. There was no mucous envelope or distinct iodinophilous vacuole.