Mansonella Ozzardi Research Articles

Specific and Cross-Reacting Antibodies in Human Responses to Onchocerca volvulus and Dracunculus medinensis Infections

Immunoelectroblotting and enzyme-linked immunosorbent assay were used to identify non-cross-reacting antigenic components of Dracunculus medinensis and the filarial worms Onchocerca volvulus, Loa loa, Wuchereria bancrofti, Brugia malayi, and Mansonella ozzardi. Parasite specific serodiagnostic ELISA systems for onchocerciasis and dracunculiasis were devised based on these findings. Phosphate buffered saline extracts of adult worms were passed through a column of monoclonal antibodies to phosphorylcholine (PC). Crude and PC-depleted extracts were reacted on ELISA plates with individual sera from subjects infected with a range of nematodes. Binding of total antibody (Ig) or IgG class antibody and IgG4 subclass antibody was revealed using goat antihuman-Ig-phosphatase conjugate, or appropriate mouse monoclonal antihuman-Ig-type-specific reagents, followed by goat antimouse-Ig-phosphatase conjugate. Specificity of ELISA was improved by restricting reaction to the host's IgG4 antibody subclass, and/or by removing PC determinants from crude antigens. In parallel immunoelectroblots, crude and PC-depleted extracts probed with pooled sera showed potentially useful diagnostic antigens, including a 12 kDa protein from D. medinensis and 14, 18, and 27 kDa proteins from O. volvulus. Two Onchocerca specific ELISA systems non-reactive with antibodies to D. medinensis were devised.

Onchocerciasis endemic in the State of Bolivar, Venezuela.

Microfilariae of Onchocerca volvulus were demonstrated by single shoulder-skin biopsy in 42.8% of inhabitants of seven Amerindian villages in an area of approximately 10,000 km2, near the Brasilian Roraima Territory. The highest prevalence was found among the Yanomama Indians of Chajuraña (84.6%, with a mean of 61.3 microfilariae per mg of skin). The six other communities were affected, but with lower prevalence and microfilaria skin densities. The absence of lymphoedema and the few subcutaneous nodules and eye lesions found among the infected individuals suggest a relatively recent introduction of the disease to the region. Mansonella ozzardi infections were also detected in the area.

The polytene chromosomes of Simulium (Ectemnaspis) ignescens Roubaud and the related species Simulium "C," both from Colombia

The paper describes the polytene chromosomes of Simulium (Ectemnaspis) ignescens from Colombia and compares them with those of a sympatric undescribed species designated Simulium "C." The two species share the entire banding sequence of chromosome arms IS, IL, and IIIS. Their IIIL arms differ by a single fixed inversion, but their second chromosomes exhibit multistep arrangement differences that were not completely resolved. The nucleolar organizer of S. ignescens is in the base of IIIS, that of Simulium "C" in the base of IS. Polymorphisms in IIS of S. ignescens exhibit partial sex linkage; no sex differential segments were demonstrated in Simulium "C." Common autosomal polymorphisms of both species involve preferentially chromosome III. Preliminary studies indicate that the chromosome maps of S. ignescens can serve as standards for other neotropical Simulium Latreille species including the important vectors of Onchocerca volvulus and Mansonella ozzardi.

4 New Benzimidazole Carbamates as Antifilarial Agents

This chapter discusses an approach to control filariasis by the use of a new class of pharmacological agents, benzimidazoles. There are six species of human filariasis for which it is desirable to develop antifilarial agents: Wuchereria bancrofti , Brugia malayi , and Onchocerca volvulus are major human pathogens, responsible for practically all filaria-related deaths. Mansonella ozzardi , Dipetalonema perstans , and Loa Loa are less prevalent species. Benzimidazoles have been identified as antifilarial agents based on an extensive series of studies in jirds (a kind of gerbil) and cats. The mechanism of the action of benzimidazoles has been extensively studied in many laboratories, and, in general, three possible modes of action have been suggested for these drugs. It has been demonstrated by numerous workers that the majority of benzimidazoles inhibit the microtubulin of tegumental or intestinal cells of nematodes or cestodes through the degeneration of these cells. This mechanism is now well accepted as the mode of action for benzimidazole derivatives.

Mansonella Ozzardi in Haiti

Sera from individuals in an area of Haiti endemic for Mansonella ozzardi were analyzed for reactivity to antigens of Brugia pahangi, Dirofilaria immitis, Mansonella llewellyni or Ascaris lumbricoides using either an enzyme-linked immunosorbent assay or an indirect immunofluorescent antibody test. IgM and IgG reactivity to all antigens was observed with sera from both microfilaremic and amicrofilaremic individuals when compared to reactivity of sera from individuals from nonendemic areas. Antibody reactivity to B. pahangi was greater than that to other antigens. IgG reactivity of sera from endemic patients to filarial antigens was consistently greater than that of IgM. Antibody reactivity was not correlated with age or microfilarial density.

Mansonella ozzardi in the Federal Territory of Roraima, Brazil. Distribution and finding of a new vector in the area of Surumu River

A survey conducted among the Makuxi Indians from 15 settlements in the northeastern part of the Territory of Roraima, Brazil, revealed the occurrence of Mansonella ozzardi in 3,2% (21/652) of the persons examined. The absence of demonstrable infection--with one exception--in persons under 15 years of age, and the low microfilaria density in adults suggest that mansonelliasis has been acquired by the Makuxi Indians outside their villages. As many Indians from the region pan gold on the Upper Maú (Ireng) river--where black flies occur in great quantity--the mining camps are probably the sites of transmission. Experimental infection with M. ozzardi of Simulium oyapockense s.l. (or Simulium roraimense) showed that this species, at the least in the Surumu river area, is capable of supporting the full development of the microfilariae. Although S. oyapockense has a wide distribution in the extreme north of Brazil, it does not appear to be an efficient vector, since only 20,6% (19/92) of the specimens collected after a blood meal on a naturally infected Indian contained larval stages of M. ozzardi (with an average of 1-2 larvae per fly). The high prevalence rate of infection found, in a previous survey, among the Sanumá and Mayongong, two Indian groups living at the Auaris river area, on the other side of the Territory of Roraima, indicates that a more competent intermediate host should exist in that region.

Experimental and natural infection of Simulium sanchezi by Mansonella ozzardi in the Middle Orinoco region of Venezuela

Experimental and natural infections of Simulium sanchezi by Mansonella ozzardi were studied in the area of Siquita, Territorio Federal Amazonas, Venezuela. The microfilariae developed synchronously in the blackflies, reaching stage L3 in seven to eight days at temperatures between 23 ° and 27 °C. Larvae in different stages of development, including infective forms, were found in 0·6% of 662 unfed wild-caught females. These results confirm that simuliids are the main vectors of M. ozzardi in the American continent.

Assessment of Culicoides barbosai as a vector of Mansonella ozzardi in Haiti.

Studies in the southern peninsula of Haiti showed that the biting midge, Culicoides barbosai, was capable of supporting the development of Mansonella ozzardi to the infective stage. The known vector, Culicoides furens, also was encountered. Both species showed distinct biting site preferences, i.e., 98% of the midges that engorged on the arms and head were C. barbosai whereas C. furens was collected mostly from the lower legs. Nine days after engorgement, 19 infective larvae were recovered from 13 C. barbosai versus six larvae from four C. furens. It was judged that C. barbosai may be as importantly involved in the natural transmission cycle as C. furens in this community.

A survey of filariasis among refugees in south Florida.

Between January 1981 and March 1982, a filariasis survey was conducted among 668 Haitian immigrants and 155 Southeast Asian refugees residing in Florida, U.S.A. Microfilariae were detected only in Haitians, with 6.7% positive for Wuchereria bancrofti and 1.3% positive for Mansonella ozzardi. The majority of individuals with bancroftian filariasis came from five coastal urban areas including Port-au-Prince, Duvalierville, Gonaïves, Leógane and Cap-Haitien. No unequivocal signs of bancroftian filariasis or mansonellosis were seen. Membrane feeding of several species and strains of laboratory-reared mosquitoes on blood from a volunteer microfilaremic with W. bancrofti showed that Aedes aegypti and A. taeniorhynchus, but not Culex quinquefasciatus, were susceptible to infection with the Haitian strain of W. bancrofti. Culicoides furens, a known vector of M. ozzardi in Haiti and present in Florida, was not tested. Further studies are needed to determine the competence of Florida vectors for transmitting W. bancrofti and M. ozzardi to the indigenous human population.

Filariasis in Colombia: prevalence of Mansonella ozzardi in the Departamento de Meta, Intendencia del Casanare, and Comisaría del Vichada.

The prevalence and distribution of filarial infections among the inhabitants of adjacent regions of the Departamento del Meta, Intendencia del Casanare, and Comisaría del Vichada in northeastern Colombia was determined by collection and examination of blood samples using the Knott's method. Mansonella ozzardi, the only species detected, was found in 2.5% of the samples collected in Meta (6/243), in 4.9% from Casanare (12/247) and in 2.5% from Vichada (3/137). All of the microfilaria carriers were Indians who had migrated from other parts of eastern Colombia, principally from the interior of Meta and Vichada. These results indicate that filariases are not endemic in the regions examined, and suggest that influx of microfilaria carriers with sufficiently high microfilaremia could establish new foci of transmission in areas where appropriate vectors are abundant.

Filariasis in Colombia: prevalence and distribution of Mansonella ozzardi and Mansonella (=Dipetalonema) perstans infections in the Comisaría del Guainía.

A survey was conducted to determine the prevalence and distribution of filarial infections among the inhabitants of Comisaría. Approximately 25% of the 604 individuals bled (Knott's sample) harbored microfilariae; more men (29.7%) were infected than women (23.7%); approximately 6% were infected with Mansonella (=Dipetalonema) perstans, 13% with Mansonella ozzardi, and 7% with both filariae. Mansonella ozzardi was more common in men than in women, and its prevalence increased with age in both sex groups; it was detected in most of the resident ethnic groups but was most common in the Puinave and the Curripaco Indians, and appeared to be distributed throughout the Comisaría. The prevalence of M. perstans was essentially the same in men as in women, and in age-groups from the 2nd to 4th decade, although its tendency to increase with age was not as marked as in M. ozzardi infections. Mansonella perstans appeared to be limited to the central and southern regions of the Comisaría, was found principally in the Curripaco Indians, and was detected in settlements situated within the drainage of both the Río Orinoco and the upper Río Negro. Approximately 9% of the white settlers (colonos) harbored M. ozzardi, and 5% M. perstans. These results indicate that both M. perstans and M. ozzardi are endemic in the Comisaría del Guainía, and suggest that the focus of M. perstans may extend further into the South American continent along the Río Negro and its tributaries.

Crypto-periodicity in Mansonella ozzardi

Studying nycthemeral microfilarial density in eight carriers of Mansonella ozzardi, Nathan et al. concluded that there is an absence of periodicity in M. ozzardi in Trinidad. Re-examination of the results obtained shows evidence of crypto-periodicity. Two of the eight patients showed highly significant periodicity but the biorhythms appear to be almost out of phase, the respective peaks being at 18·00 hours and 02·00 hours. The six other patients showed no obvious periodicity; the calculated acrophases (peak hours), instead of being randomly spaced, regrouped with the preceding ones: late afternoon in two subjects and in the second half of the night for the other four. It is concluded that the apparent non-periodicity is due to the co-existence of two periodic forms, but these are markedly out of phase.

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.

Development of Mansonella ozzardi in Simulium amazonicum, S. argentiscutum, and Culicoides insinuatus from Amazonas, Colombia.

Simulium amazonicum, S. argentiscutum and Culicoides insinuatus were collected from the Amazon region of Colombia after having blood-fed on volunteers naturally infected with Mansonella ozzardi. Dissection of the specimens revealed that these species supported the development of the microfilaria of M. ozzardi to the infective stage. Infective larvae were obtained from Simulium within 7 days at temperatures ranging from 23-30 degrees C. S. argentiscutum ingested more microfilariae and had a correspondingly higher experimental infection rate. Three of 31 C. insinuatus dissected beyond day 5 postfeeding contained one advanced second-stage and two third-stage larvae. The current investigation indicates that Culicoides, as well as Simulium, may serve as vectors of mansonelliasis in the Comisaría of Amazonas.

Mansonella Ozzardi in Haiti

A study to compare the sensitivity of four sampling methods in detecting Mansonella ozzardi among 133 inhabitants of Bayeux, Haiti, is reported. The Knott method proved the most sensitive with 40 microfilaria carriers detected. No additional infections were revealed by the other sampling methods. This was followed in order by 20 mm3 thick films of earlobe blood (34 cases), finger-prick blood (32 cases in the first sample), and skin biopsy (14 cases from paired samples). The combination of three finger-prick samples (60 mm3 of blood) detected 38 of 40 (95%) Knott-positive infections. The Knott method detected only one case not observed by at least one of the other three sampling methods. This sampling procedure did not detect more M. ozzardi in the 0-19-year age group than observed by the 20-mm3 finger prick method. Based on these results, a correction factor of 1.25 can be applied to our earlier Bayeux survey.

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.

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.

Mansonella ozzardi in Haiti II. Arthropod vector studies.

The present vector studies show that the biting midge, Culicoides furens, serves as an intermediate host for Mansonella ozzardi in Haiti. A total of 3,430 C. furens were collected as they engorged on infected individuals. Under the maintenance conditions described herein, the microfilaria required 9 days to reach the infective stage. Approximately 43% of the midges survived, and from these 1,128 infective stage larvae were collected. This represents an overall infection rate of 0.76 larva per midge. Typically, there was a directly proportional relationship between the infection rate in midges and the level of microfilaremia in the individuals upon whom the C. furens fed. Also, the vector efficiency of C. furens collected from saltwater or freshwater breeding habitats was comparable.

Development of Mansonella ozzardi in a black fly species of the Simulium sanguineum group from Eastern Vaupés, Colombia.

Development of the microfilaria of Mansonella ozzardi to the infective stage in a species of the Simulium sanguineum group from the Mitú area, Comisaría del Vaupés, Colombia is described. Development was synchronous, and by day 6 third-stage larvae were observed in the head of flies which had fed on two naturally infected volunteers. Simulium biting activity was high from January-March, during the dry season. Only 261 blood-fed Culicoides were collected from an infected volunteer; 40% of 43 dissected on day 0 had ingested microfilariae. However, only one of 129 C. caprilesi specimens dissected after day 2 was positive, containing a second-stage larva thought to be M. ozzardi. It is concluded that Simulium, rather than Culicoides are the principal vectors of mansonelliasis in the Mitú area.

Mansonella ozzardi in Haiti. I. Epidemiological survey.

A survey of 1,165 inhabitants of Bayeux, Haiti revealed that 16% were infected with Mansonella ozzardi. This was determined from a single 20 mm3 sample of finger prick blood from each individual. Amont children and young adults (< 20 years of age), fewer than 2% had detectable microfilaremias. Beyond this age the prevalence of infection for males and females was 49% and 24%, respectively. The microfilariae circulate in the peripheral blood with no significant periodicity. In general, the microfilaremias were low, with 71% of the positive cases having less than 10 microfilariae in 20 mm3 of blood; only 4% had more than 50 microfilariae. Histological examination of sectioned skin biopsies showed that the microfilariae dwell within the superficial capillary vessels; not free in the extravascular tissues.