Development of Mansonella ozzardi in the Liverpool strain of Aedes aegypti.
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Aedes↗
Biomedical subjects
M L Eberhard
Publications and source records attributed to M L Eberhard.
Variable infectivity of third-stage larvae of Brugia malayi.
Infectivity of third-stage larvae of Brugia malayi was assessed following intraperitoneal inoculation into jirds, Meriones unguiculatus. Larvae were of two ages and were derived from two sites in Aedes aegypti mosquitoes, i.e., specimens collected from the thorax 11 days after infection and from the head on day 14. Larvae from the thorax had just completed the second moult and measured 990 to 1100 micron in length. Only 6% of these specimens developed to adult worms in jirds. Larvae that migrated to the head were 1400 to 1700 micron long on day 14 and, in contrast, 23% of the inocula developed to adult worms. This study establishes that all third-stage larvae, regardless of their age or location in the arthropod host, are potentially infective. However, pronounced physical maturation does seem to be accompanied by a marked increase in infectivity.
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Activation of the alternative complement pathway in normal human serum by Loa loa and Brugia malayi infective stage larvae.
Infective stage larvae (L3) of Loa loa and Brugia malayi upon in vitro incubation with normal human serum activated the alternative complement pathway. C3 conversion products were detected on larval cuticles by eosinophil adherence and by immunofluorescence with C3c antiserum. No evidence for cuticle binding of IgG, IgA, IgM, Clq, or C4 was found by immunofluorescence. L3-induced C3 activation was inhibited by 10 mM EDTA but unaffected by 10 mM Mg++-EGTA. Human sera deficient in C2, C4, or C6 incubated with L3 resulted in C3 activation. However, sera treated with zymosan or heated for 1 h, 56 degrees C were unreactive with L3. Immunoelectrophoresis of fresh serum exposed to L3 for 1 h at 37 degrees C showed C3 cleavage products. The results indicate that these nematode L3 activate the alternative complement cascade via cuticular surface components. Larval viability was unaffected by complement activation or by adherence of eosinophils.
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Loa loa: development and course of patency in experimentally-infected primates.
Loa loa infections were studied in baboons, rhesus and patas monkeys. Animals were infected either by s.c. injection of third-stage larvae (L 3) or by surgical implantation of juvenile worms of known age, sex and number. Microfilaremia was first detected in baboons at 140 days following inoculation of L 3 and at 142 days and 143 days in patas and rhesus monkeys, respectively; the mean prepatent period was 151 days in baboons, 149 days in patas monkeys and 169 days in rhesus monkeys. The primary wave of microfilariae (mf) was suppressed by the spleen in all three primate species. In baboons, the initial wave of mf lasted from 11 to 46 weeks (mean: 22 weeks), whereas in patas monkeys it persisted for 47 to 60 weeks, and in rhesus monkeys for 1 to 2 years. Gross and microscopical changes in the spleen were noted in all three primate species and consisted of numerous granulomata in the red pulp underlying the capsule. A resurgence of mf was observed following splenectomy in all three species of monkeys. Postsplenectomy levels of microfilaremia typically exceeded presplenectomy levels. One pair of worms was sufficient to produce patent infections in monkeys for extended periods of time. However, levels of microfilaremia were lower than in monkeys which received 75 and 200 to 300 L 3, although some overlap in microfilaremias between groups did occur. Overall, there was no proportional relationship between levels of microfilaremia and numbers of adult worms recovered from monkeys at necropsy. It was observed that, in the primate host, Loa is a long-lived parasite. Living worms were recovered from the tissues as long as 9 years after inoculation and there was no reason to doubt that patency would have persisted for some time into the future. Adult worms were frequently observed moving freely in the subcutaneous tissues of the primate hosts, although no instance of Calabar swellings or the presence of worms in or around the eye were ever recorded. The primate model of loiasis is an especially useful system because of the predictability of the behavior of the parasite. In most regards, the behavior of L. loa in the primate host is comparable to observations on the parasi e in man.(ABSTRACT TRUNCATED AT 400 WORDS)
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Loa loa: antibody responses in experimentally infected baboons and rhesus monkeys.
Antibody responses to Loa loa in experimentally infected baboons and rhesus monkeys were measured using an adult L. loa antigen in a kinetic enzyme-linked immunosorbent assay. Animals were infected with infective stage larvae or by transplantation of juvenile worms. There were no differences between host species in antibody response and there was no relationship between adult worm numbers recovered at necropsy and antibody level. Antibody levels tended to be inversely correlated to the number of circulating microfilariae and decreased concommitant with the onset of patency. Following an initial wave, suppression of the microfilaremia was observed. Although the microfilaremia recrudesced following splenectomy, no changes in the antibody levels were noted pre or postsplenectomy. An antibody response was not demonstrable in baboons infected by transplantation of juvenile worms. Although a primary suppression of the microfilaremia by the spleen still occurred.
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Development of Dipetalonema gracile in the squirrel monkey (Saimiri sciureus), with notes on its biology.
Infective larvae of Dipetalonema gracile, which had developed in Culicoides hollensis, were inoculated into 4 laboratory-born squirrel monkeys, Saimiri sciureus. Weekly blood sampling revealed the mean prepatent period to be 297 days. All 4 monkeys developed patent infections in which peak microfilaremias were reached 13 to 18 wk after patency. Two laparotomies, performed at 27 and 64 wk, were conducted to evaluate pathological involvement and, at that later time, to recover adult parasites. Slight capsular fibrosis was observed on the spleen of 2 of the animals but fibrous adhesions were absent. Microfilaremias in the 4 monkeys ranged from 15 to 250 mf/20 mm3 of blood and the number of adult parasites recovered varied from 7 to 13. However, the level of microfilaremia did not correlate directly to the number of adult parasites recovered.
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The genus Mansonella (syn. Tetrapetalonema): a new classification.
Mansonella has been established as a valid genus, and Tetrapetalonema synonymized with it. Comparative morphological studies have resulted in the restructuring of the Mansonella group. The genus is characterized by the following features: cuticular pre-esophageal ring absent; esophagus slender, poorly differentiated; female tail with four terminal papillae; caudal papillae in male typically clustered around cloaca; and, microfilariae without sheath. Twenty-four species are assigned to the genus Mansonella. Five subgenera are proposed to accommodate these species. The subgeneric groups are distinguished principally on morphological criteria, although host range and geographical distribution are considered. The following systematic classification is proposed: Mansonella (Mansonella) subgen. n., to accommodate those species which have the following morphological features: cephalic extremity with dorsoventral orientation; male tail with tip flattened dorsoventrally; vulva in midesophageal region; and microfilariae without nuclei extending to tip of tail. Type species is M. (M.) ozzardi. Mansonella (Tupainema) subgen. n., to accommodate the single species M. dunni with the following characters: cephalic extremity with lateral orientation and body constricted to form cephalic extremity in shape of hemisphere narrower than body behind it; tip of male tail not flattened dorsoventrally; vulva at or posterior to base of esophagus; and, microfilariae without nuclei to tip of tail. Mansonella (Esslingeria) comb. n., to accommodate those species with the following characters: cephalic extremity with lateral orientation; male tail flattened dorsoventrally at tip or not; vulva in midesophageal region; and, microfilariae with nuclei to tip of tail. Type species is M. (E.) perstans. Mansonella (Tetrapetalonema) comb. n., to accommodate those species with the following characters: cephalic extremity with dorsoventral orientation or with body constricted to form cephalic extremity in shape of hemisphere narrower than body behind it; male tail not flattened at tip; vulva in midesophageal region; and, microfilariae with nuclei to tip of tail. Type species is M. (T.) marmosetae. Mansonella (Sandnema) comb. n., to accommodate those species with the following characters: cephalic extremity rounded, not oriented along lateral or median axis; tip of male tail not flattened; caudal papillae on male tail not clustered around cloaca; vulva near base of esophagus; and, microfilariae with nuclei to tip of tail. Type species is M. (S.) digitata.
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Mansonella (E.) rotundicapita sp.n. and Mansonella (E.) longicapita sp.n. (Filarioidea : Onchocercidae) from Venezuelan capybaras, Hydrochoerus hydrochaeris.
Mansonella (E.) longicapita sp. n. and Mansonella (E.) rotundicapita sp. n., two filarial nematodes from the dermis of Venezuelan capybaras, are described. The two species can be distinguished on the size of the spicules (M. longicapita 327 and 139 micron, ratio of 2.3 : 1 ; M. rotundicapita 405 and 120 micron, ratio of 3.4 : 1), the degree of lateral elongation of the cephalic shield and in the size and configuration of the microfilaria. The microfilaria of M. rotundicapita is large (280 micron long), and in specimens fixed in 2% formalin, the posterior end of the body is bent in a shepherd's crook, while the microfilaria of M. longicapita is short (195 micron long) and when similarly fixed, assumes a gently curved attitude. Within the subgenus M. (Esslingeria), the species M. longicapita and M. rotundicapita are intermediate in size. Morphologically they resemble M. streptocerca and M. rodhaini most closely, but can be distinguished on size, spicule morphology, and microfilarial morphology.
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Brugia lepori sp. n. (Filarioidea: Onchocercidae) from rabbits (Sylvilagus aquaticus, S. floridanus) in Louisiana.
Brugia lepori sp. n., a filarial nematode from the abdominal lymphatics and subcutaneous tissues of rabbits (Sylvilagus aquaticus, S. floridanus), from St. Tammany Parish, Louisiana, is described. Brugia lepori is of moderate size (males 12 to 19 mm, females 39 to 45 mm) and within the genus most closely resembles Brugia beaveri of the raccoon, from which it can be distinguished by its larger size, smaller spicules, and smaller microfilaria which has a shorter cephalic space. Brugia lepori is only the second species of Brugia described from North America and the third species reported from the Western Hemisphere.
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Diagnostic exercise. Cutaneous acariasis.
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Assessment of Leptoconops bequaerti as a potential vector of Mansonella ozzardi in Haiti.
Experimental studies in Bayeux, Haiti showed that the biting midge, Leptoconops bequaerti, is capable of supporting the complete development of Mansonella ozzardi but only on a very limited scale. This suggests that the species may not be involved in the natural transmission cycle despite its abundance and pestiferous nature in certain areas of Haiti. A midge-holding container is described which markedly enhanced the survival of engorged L. bequaerti in the laboratory.
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Comparative morphology of Mansonella ozzardi microfilariae from Colombia and Haiti. A light microscope study.
Comparative morphological studies were conducted at the light microscope level to determine whether any difference could be detected in thin smears, thick smears, or Knott samples, between Colombian (simuliid-transmitted) and Haitian (culicoid-transmitted) Mansonella ozzardi microfilaria. Results indicated that the microfilariae from these two geographical areas are essentially identical. The small differences observed in the dimensions of microfilariae in thick and in thin smears can be attributed to different preparative procedures. The consistent morphological differences, noted in PAS-hematoxylin-stained microfilariae, from Knott smears, was that the central body was thinner and stained less intensely with the Schiff reagent in the Haitian than in the Colombian microfilariae. Although these observations suggest a physiological difference between these two forms, additional studies are needed to exclude the possibility that these differences are not indications of the age or a state of physiological activity of the microfilariae.
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Mansonella ozzardi: a redescription with comments on its taxonomic relationships.
Mansonella ozzardi is redescribed from adult worms collected from the subcutaneous tissues of patas monkeys (Erythrocebus patas) infected with a Haitian strain of the filaria. The worms are small and very slender; females measure about 49 mm in length by 0.15 mm in diameter and males, 26 by 0.07 mm. Haitian (Caribbean) and Colombian (Amazon) forms of the filaria are morphologically identical, as are their microfilariae. Mansonella is most closely related to Tetrapetalonema. Based on taxonomic priority the latter becomes a synonym of Mansonella. As a consequence, T. perstans and T. streptocerca of man in Africa are designated as M. perstans (Manson, 1891) n. comb. and M. streptocerca (Macfie and Corson, 1922) n. comb. Further, M. ozzardi is most closely related to the species M. llewellyni (Price, 1962) n. comb., a parasite of the raccoon, and M. interstitium (Price, 1962) n. comb. found in squirrels, both in North America.
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Culicoides variipennis, a laboratory vector for the amazon form of Mansonella ozzardi.
The colonized midge, Culicoides variipennis, is shown to be a competent laboratory host for the Amazon form of Mansonella ozzardi. It raises the possibility that certain Culicoides spp. in the Amazon region may support development of the parasite and possibly play a role in the natural transmission cycle.
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Chemotherapy of filariasis in squirrel monkeys (Saimiri sciureus).
The effect of some known antifilarial drugs on naturally-occurring filariae in squirrel monkeys, Saimiri sciureus, was evaluated. Four drugs, dithiazanine iodide, naphuride sodium, thiacetarsamide sodium, and diethylcarbamazine were tested against Dipetalonema gracile and Tetrapetalonema marmosetae. Dipetalonema caudispina was included in some of the studies using diethylcarbamazine. These are the three most commonly encountered filarial species in squirrel monkeys. Dithiazanine iodide proved to be unsuitable for use because of lack of acceptance by the monkeys. Naphuride sodium (10 mg/kg/week for 5 weeks) did not exert filaricidal activity against the species tested during a 7-month evaluation period. Thiacetarsamide sodium (0.22 ml/kg twice daily for 2 days) had lethal effects on the adult parasites, but not the microfilariae, of all species tested. Diethylcarbamazine (50 mg/kg/day for 10 days) was found to be effective against both microfilaria and adults of all filarial species tested. Monkeys given this regimen were microfilaria-negative for 12-24 weeks following treatment.
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Dirofilaria immitis infection in a rhesus monkey (Macaca mulatta).
A spontaneously occurring Dirofilaria immitis infection was diagnosed in a rhesus monkey at necropsy. A single immature worm was found in the right ventricle. Granulomatous eosinophilic arteritis was present within pulmonary arteries in the lung. No microfilariae were found.
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Dipetalonema (Dasypafilaria) averyi subgen. et sp. n. (Nematoda: Filarioidea) from the nine-banded armadillo, Dasypus novemcinctus in Louisiana.
A new filarial nematode, Dipetalonema (Dasypafilaria) averyi subgen. et sp. n., is described from the omentum of armadillos (Dasypus novemicinctus) for southern Louisiana. Within the genus, the large buccal cavity, the absence of a gubernaculum, the reduced number of caudal papillae, the large caudal lappets, and the sheathed microfilaria serve to distinguish the subgenus Dasypafilaria from other subgenera. The small size of D. averyi (females 5.3-9.5 mm long by 70-90 micrometers wide; males 3.8-5.5 mm long by 46-70 micrometers wide) readily distinguishes it from other species in the genus. It also is distinguished by its rounded cephalic extremity, the location of the vulva at the level of the base of the esophagus, the morphology of the spicules, and the size and configuration of the microfilaria.
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Susceptibility of laboratory primates to infection with Mansonella ozzardi from man.
The study was undertaken to determine primates were susceptible to infection with Caribbean and/or Amazon strains of Mansonella ozzardi of man. Twenty-three animals including three chimpanzees, four squirrel monkeys, one capuchin, five rhesus and 10 patas monkeys each received, by subcutaneous or intraperitoneal injection, 25-170 infective larvae of M. ozzardi harvested either from infected Culicoides furens collected in Haiti or Simulium sp. (sanguineum complex) collected in the Colombian Amazon and transported to our laboratories in Louisiana. Patent infections were obtained in seven of 10 patas monkeys but not in any other species of primates. The prepatent period ranged in duration from 149-186 days with a mean of 168 days. All of the patas monkeys developed modest microfilaremias that persisted for as long as 1 year, the duration of our observations. Adult worms were obtained at necropsy from three of four patas monkeys. The worms were recovered from soakings of the carcass and skin rather than from the abdominal cavity and mesenteries. However, their precise habitat was not determined.
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