[Discrimination of geographic strains of periodic Brugia malayi by the cuticular ornamentation of the male]

A comparative study of five periodic human strains of Brugia malayi, originating from India, China, Korea, Malaysia and Indonesia, is given. This morphological analysis is based on males; the "standard" characters (oesophagus, papillae, spicules...) appear identical. On the contrary, the cuticular ornamentation of the posterior region--which is composed of the area rugosa and of a system of bosses and constitutes a secondary non-skid copulatory apparatus--differs following the geographical origin of the strain. A key is given, based on this character. 1(2) At 800-1,200 micron from the tip of tail, numerous cuticular bosses present on the right side of the body (fig. 2 and 8 B). 2(1) At 800-1,200 micron from the tip of tail, cuticular bosses absent or scarce on the right side of the body (fig. 8 D). 3(4) At 1,800-1,200 micron from the tip of tail (fig. 4), scarce and slightly projecting cuticular bosses on the dorsal side of the body contrasting with well projecting lateral cuticular bosses (fig. 9 E and F). Anterior extremity of the area rugosa made by a few stripes of tiny bosses linked transversally (fig. 9 A). 4(3) At 1,800-2,200 micron, numerous cuticular bosses on the dorsal side of the body (figs. 5, 6 and 7). Anterior extremity of the area rugosa made by the stripes of longitudinal rods (fig. 9C). 5(6) Oblong transversally stretched cuticular bosses on the dorsal and left sides of the body, anteriorly to the area rugosa (fig. 5); big oblong bosses on the left side (fig. 9 B). Transversal wrinkles and stripes of rods absent on the dorsal side of the body. 6(5) Round cuticular bosses on the dorsal and left sides of the body anteriorly to the area rugosa (figs. 6 and 7): no big oblong bosses on the left side. Transversal wrinkles or stripes of rods present on the dorsal side of the body (fig. 9 D). Nomenclaturally, such differences could be used in defining different taxa, but it could be useful to perform "blind determination" (material without labelling), to study conveniently the morphology of microfilariae (often an excellent indication for speciation in that group of Nematodes) and, evenly, to proceed to parallel studies on isoenzymes. However, whatever could be the taxonomical conclusion, the differences observed in Brugia malayi originating from different regions appear to the sufficient to consider the existence of four distinct diseases.

Monoclonal antibody to a unique surface epitope of the human filaria Brugia malayi identifies infective larvae in mosquito vectors

We describe properties of an IgM monoclonal antibody (NEB-D1E5) raised against the human filarial parasite Brugia malayi. The antibody reacts with a stage- and species-specific determinant located on the surface of the infective-stage larva, as determined by indirect immunofluorescence. To use this reagent in epidemiological field studies, we developed an enzyme-linked immunoassay with which B. malayi larvae can be differentiated from other filarial parasites in mosquito vectors, including the morphologically indistinguishable parasite of animals Brugia pahangi. The immunoenzyme assay was 91-94% specific and 90-97% sensitive when performed on infected mosquitoes. In the absence of mosquito tissue, the levels of specificity and sensitivity increased to 100% and 97.5-100%, respectively. Binding of antibody to the surface of living larvae was abrogated by treatment of the worms with the enzymes pronase and proteinase K and with the detergents Triton X-100, octyl beta-D-glucopyranoside, and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulphonate (CHAPS). In contrast, treatment with trypsin, endoglycosidase-F, O-Glycanase, N-Glycanase, lipase, various phospholipases, boiling, 2-mercaptoethanol at 37 degrees C, or periodate did not reduce the antigenicity of the larval surface to antibody NEB-D1E5. These results suggest that the species-specific epitope is a peptide domain attached to a hydrophobic anchoring residue.

Periodicity studies of Brugia malayi in Indonesia: recent findings and a modified classification of the parasite

We have recently reinvestigated the position of Brugia malayi in Indonesia. Periodicity patterns of microfilariae from several endemic areas were mathematically determined. We have also designed a simple method to quantify microfilaria periodicities in these studies. To determine whether periodicity patterns of microfilariae were stable, repeated studies were performed in the same individual or community. Other biological features of the parasite were also investigated. The parasite from each isolate was taxonomically identified as B. malayi. It could be classified into two distinct biological types, one nocturnally periodic and the other aperiodic, nocturnally subperiodic, or nocturnally periodic. We therefore propose to modify Wilson's classification, using the biological behaviour of the parasite in animals as the discriminating feature, and classify the two types as zoophilic and anthropophilic B. malayi.

Antigenic characterization of adult Wuchereria bancrofti filarial nematodes

Adult Wuchereria bancrofti were recovered from infected Presbytis cristatus monkeys and radio-isotope labelled extrinsically with 125I and in vitro with [35S]methionine. 125I labelling of the surface of adult W. bancrofti permitted a comparison between the major surface antigens of this species and those from the related lymphatic filariae, Brugia malayi and B. pahangi. All species bear a prominent Mr 29,000 surface antigen but among the differences observed were the strongly labelled molecules with Mr 58,000 and 67,000 in W. bancrofti which are extremely faint in the Brugia species. The [35S]methionine label was effectively incorporated into somatic parasite proteins in vitro although it was not possible to identify any secreted proteins in this way. The antigenicity of these products was investigated using a variety of sera from homologous and heterologous infections and the immunoprecipitation patterns highlighted particular differences between somatic proteins of male and female worms. One secreted antigen was detected, however, by virtue of its phosphorylcholine epitopes, in the culture medium of mixed adult worms; medium from male W. bancrofti adults was negative although homogenates of either sex of adult W. bancrofti were strongly positive in the same system.

Secreted and surface antigens from larval stages of Wuchereria bancrofti, the major human lymphatic filarial parasite

Antigenic proteins of microfilariae and infective larvae of Wuchereria bancrofti have been identified by intrinsic and extrinsic radiolabelling, and specific immunoprecipitation with sera from filarial patients. From 125I surface-labelling experiments, the most prominent antigen on both stages is of relative molecular mass (Mr) 17 000, while a molecule of similar size is both synthesized and released in vitro following labelling with [35S]methionine. A second similarity between the two stages is the production and secretion of a Mr 21 000 component, which is, however, not detected on the worm surfaces. A series of additional proteins from larval W. bancrofti are described from each parasite compartment (secreted, surface and somatic) and the antigenicity and specificity of these components explored with serum from patients with filariasis due to W. bancrofti or Brugia species, and with onchocerciasis. Among additional molecules released in vitro we have found a Mr 51 000 antigen from both stages, and also several proteins which are not recognised by antibody from human filarial patients.

Molecular characterization of antigens of lymphatic filarial parasites

Three species of filarial worms,Wuchereria bancrofti, Brugia malayiandBrugia timori, are the causative agents of lymphatic filariasis in man, defined by the characteristic tropism of adult worms of each species for the afferent lymphatics. Reproductive activity leads to the release of large numbers of microfilariae, which circulate in the vascular system, and upon ingestion by an appropriate mosquito vector, develop through to infective third-stage larvae (L3) within 10–14 days. After a subsequent bloodmeal, the infective larvae enter the definitive host via the wound and mature to the adult stage over several months, involving two moults, during which the entire nematode exoskeleton (cuticle) is replaced.

Combined low dosage and short term standard dose treatment with diethylcarbamazine to control Timorian filariasis

A combined weekly low dosage and short term standard dose treatment with diethylcarbamazine (DEC) to control Timorian filariasis is described. Weekly low dosage DEC was distributed by the village chief to all villagers for 6 months. The dosage of DEC was 50 mg weekly for group A, and 100 mg for group B. Children below 10 years of age received half the adult dose. Following the initial phase of low dosage treatment, 5 mg DEC/kg was distributed by one of us to all villagers for 6 consecutive days. The results of treatment were evaluated approximately one year later. There was no difference between the results of treatment with 50 mg DEC weekly compared to the 100 mg dosage. The microfilaria, adenolymphangitis and lymphoedema rates decreased drastically in both groups, similar to the results of our previous studies. Side reactions during low dosage and standard dose treatment of DEC were characteristically mild.

Adverse reactions to a single dose of diethylcarbamazine in patients with Brugia malayi infection in Riau Province, West Indonesia

A study on the adverse reactions, occurring after treating microfilaremic patients infected with B. malayi, revealed that all reacted to a single oral dose of DEC (5 mg/kg). The major reactions were fever, headache, anorexia, abdominal pain, muscle and joint pains, nausea and vomiting. There seemed to be no association between the time of fever onset and microfilarial density, but the number of cases observed was too small to make any firm conclusion. There was a tendency for more severe reactions to occur in patients with higher microfilaria counts. Local reactions, probably due to destruction of adult worms, were seen in 3 patients. The reactions were serious enough to necessitate the patients spending approximately 48 hours in bed.

Diagnosis and treatment of lymphatic filariasis

The lymphatic filariases, Wuchereria bancrofti, Brugia malayi, and B. timori, infect nearly 100 million people throughout the tropics, but mainly in Africa and southeast Asia. Over 900 million people live in endemic, areas at risk to the infection. The filarial parasites reproduce slowly, whereas their mosquito vectors are quickly-reproducing opportunists. Thus, although vector control can reduce the risk of transmission, the parasite itself would seem a more vulnerable target for prolonged attack. In this article, Felix Partono discusses the clinical diagnosis of f lariasis and argues that the disease can be effectively controlled by attacking the parasites in infected communities, using diethyl-carbamazine (DEC) as the drug of choice.

Treatment of elephantiasis in a community with timorian filariasis

To elucidate the issue of lymphoedema and elephantiasis in our previous reports, all data on the two clinical conditions have been reviewed and analysed. The various characteristics of the swelling are described and factors that may influence the outcome of treatment with diethylcarbamazine (DEC) analysed. The results showed that all cases with lymphoedema could be treated with DEC, irrespective of the size of the swelling, and that in most cases the swelling disappeared within one year. On the other hand, it required at least two to four years for most swelling to disappear in people with elephantiasis. Elephantiasis of the arms was easier to treat than of the legs. Bilateral elephantiasis of the legs were more difficult to treat than unilateral elephantiasis. Elephantiasis of less than three to five years' duration were easier to treat than that of longer duration. Individuals with a higher grade of elephantiasis were more difficult to treat than those with a lower grade of elephantiasis. The age and sex of patients did not influence the outcome of treatment.

Low dosage diethylcarbamazine administered by villagers for the control of timorian filariasis

The results of mass treatment using low dosage diethylcarbamazine (DEC) in three small villages in West Flores, Indonesia, endemic for Brugia timori are described. DEC was distributed on a weekly basis by motivated persons in the community to nearly all villagers for 18 months. An educational programme was developed which focused on describing the relationship between microfilaraemia, vector and disease manifestations, the danger of repeated attacks of adenolymphangitis, and the efficiency of DEC in eliminating the parasites and attacks. During the consolidation phase motivated persons were assigned to treat promptly all cases with acute filariasis and to distribute DEC to all new residents. With this programme the microfilaria rates decreased to very low levels, even as detected by the use of membrane filtration techniques. The adenolymphangitis rates also decreased. An unexpected bonus was the cure of "elephantiasis" in many people. Mild side effects attributed to DEC were encountered only during the first few weeks of treatment.

Cross-reactive surface antigens on three stages of Brugia malayi, B. pahangi and B. timori

Surface antigens of three stages of three species of the filarial nematode genus Brugia have been analysed by radio-iodination and immunoprecipitation. These surface antigens have been shown to be characteristic for each stage by polyacrylamide gel electrophoresis. For example, infective larvae and adult worms have relatively complex patterns while microfilariae have few bands which are not found when other stages are radio-isotope labelled by the same technique. The surface antigens of Brugia malayi, B. timori and B. pahangi adult worms are all closely homologous, as are the surface antigens of infective larvae of the same three species, and of microfilariae of B. malayi and B. pahangi. Immunoprecipitation revealed that antibody raised in mice against one stage or species reacted with surface antigens from other stages and species. For example, sera raised against B. pahangi male adults reacted strongly with surface antigens from all three species. This cross-reactivity was dominant despite the apparent stage-specificity of the surface pattern seen on SDS-PAGE analysis. Moreover, in cross-immunization experiments, infective larvae were able to stimulate a secondary antibody response in mice previously primed with microfilarial surface antigens. The major microfilarial surface antigens (of mol. wt 65-70 000 Daltons) were recognized by serum antibody from microfilariae-, infective larvae- or adult-infected animals. Thus, although the dominant antigens from each stage are of different molecular weight, cross-reactions with stage-specific antisera suggest that there must be shared epitopes on Brugia surface antigens from each stage. Such shared antigenic determinants dominate the immune response, although other evidence, including the differences in molecular weight, indicates the existence of stage- and species-specific components.

Antigenic analysis of Brugia timori, a filarial nematode of man: initial characterization by surface radioiodination and evaluation of diagnostic potential

The antigenic composition of Brugia timori has been investigated with surface labelling techniques and defined sets of parasite molecules have been identified on infective larvae, adult worms and microfilariae. Iodinated preparations from all three stages were assessed for immunodiagnostic potential with a small number of serum samples from human filariasis patients. In these tests, reaction with infective larval antigen was the clearest indicator of infection. Reactivity to microfilarial antigens however, correlated poorly with incidence of infection. These experiments show that levels of anti-parasite antibody appear to increase as filarial disease becomes more severe. In contrast to some reports, antibody to microfilarial surface antigens is present in sera from several patients with circulating microfilariae. The immunodiagnostic potential of these tests is indicated by the detection of a few individuals who have high levels of antibody but no outward signs of infection.

Antigen-specific suppressor T lymphocytes in human lymphatic filariasis

Immune responses to parasite antigens are much lower in patients with microfilaremia than in persons with other manifestations of brugian filariasis. To determine whether hyporeactivity is associated with changes in populations of lymphocytes that regulate immune responses, we quantitated helper and suppressor T cells in the blood of patients infected with Brugia malayi. Increased numbers of suppressor T cells were present in 15 of 17 patients with microfilaremia and in six of 11 patients with elephantiasis. This increase correlated with hyporeactivity to filarial antigens but not to nonparasite antigens. Removal of suppressor T cells activated in vivo or in vitro improved reactivity to filarial antigens. These results suggest that immunosuppression induced by filarial parasites is a possible mechanism of survival of these organisms in an immunocompetent host.

The long term effects of repeated diethylcarbamazine administration with special reference to microfilaraemia and elephantiasis

The result of mass treatment with 50 mg diethylcarbamazine (DEC) per kg body weight followed by two annual selective retreatments in an area highly endemic for Brugia timori infections are described. The criteria for selective re-treatment are simple and practical for use in rural areas. An education programme was developed which focused on describing the relationship between adenolymphangitis and filarial infections, the danger of repeated attacks and the efficiency of DEC in eliminating these attacks. Motivated persons in the community were charged with the responsibility of promptly treating all cases with acute clinical manifestations. With this programme the microfilaria rate by finger prick decreased from 24% to 0%, and by Nuclepore filtration from 30% to 5%. The adenolymphangitis rate decreased from 46% to 11% and the "elephantiasis' rate from 17% to 4%.

Further studies on the development of Wuchereria bancrofti in laboratory animals

In an attempt to obtain a small animal laboratory model for Wuchereria bancrofti Mongolian gerbils and hamsters were infected with third-stage larvae of strains of the parasite from Indonesia and China. Gerbils were necropsied at 7 to 591 days and larvae recovered up to 219 days. The third molt occurred on or before 10 days and worms found after 14 days were in the fourth stage. More worms were recovered early in the infection (7 to 30 days) than in older infections. The worms were usually recovered from the testes, pelt and carcass and heart and lungs. An adult male worm was recovered on one occasion from the lung of a gerbil at 92 days. The parasite was also found to develop in hamsters with results similar to those in gerbils. Gerbils and hamsters were given antithymocyte sera before and after infection and more worms were recovered and the worms larger in size in some treated animals. Continued studies with geographic strains of W. bancrofti in various animals should be encouraged in order to find a small laboratory animal model for the parasite.

A study on vectors of Bancroftian filariasis in West Flores, Indonesia

A brief survey was conducted in a filariaendemic village of Robek, West Flores, Indonesia, to identify the mosquito fauna, to determine the vector of W. bancrofti, and to update information on the bionomics of An. subpictus. A total of 6 genera and 22 species were collected. Five species of culicines collected, have not been previously recorded from Flores. Dissections of wild caught mosquitoes consisted of 592 anophelines, and 70 culicines did not reveal any filarial infection. An. subpictus was a potential vector of bancroftian filariasis in the Robek area, as 11.3% of this species that fed on carriers were found to harbour W. bancrofti larvae. Larvae of An. subpictus were collected in lagoons, rice fields, swamps and ground pools. Breeding sites are exposed to sunlight, contain fresh or brackish water, with or withour vegetation. They have been found primarily associated with An. aconitus, An. annularis, An. barbirostris, Cx. vishnui and Cx. bitaeniorhynchus. The time for a female to become fully engorged with human blood is 3-10 minutes. This species is a night biter, attacking man and animals from twilight to dawn. Its peak of biting activity is between 0100-0300 hrs.

Human intestinal parasites in Karakuak, West Flores, Indonesia and the effect of treatment with mebendazole and pyrantel pamoate

A survey for intestinal parasites and mass-treatment with a combination of mebendazole and pyrantel pamoate were conducted in Karakuak, West Flores in 1977. A total of 198 stool specimens from 104 males and 94 females ranging in age from less than 1 to 70 years were examined and 72% harbored one or more intestinal parasites. Ascaris lumbricoides (43%) and Entamoeba histolytica (21%) were the most common, followed by Entamoeba coli (19%), hookworm (18%), Iodamoeba bütschlii (8%), Giardia lamblia (5%) and Trichuris trichiura (4%). Other intestinal parasites infrequently found were: Entamoeba hartmanni (2%), Chilomastix mesnili (2%), Endolimax nana (1%), Enterobius vermicularis (1%) and a heterophyid sp. (1%). A combination of mebendazole base at 200 mg/day and pyrantel pamoate salt at 60 mg/day for three consecutive days was 100% effective.

Experimental transmission of Wuchereria bancrofti to monkeys

Infective larvae of Wuchereria bancrofti from laboratory-raised Culex pipiens fatigans and Aedes togoi mosquitoes fed on human volunteers in Jakarta, Indonesia (J strain) and Kinmen Island, China (K strain) were introduced into Taiwan monkeys (Macaca cyclopis) by subcutaneous inoculation, by foot puncture, or by permitting infected mosquitoes to feed weekly on the monkeys. Some animals were splenectomized and others were treated with varying regimens of immunosuppressants. Necropsy was done on monkeys that died or were killed and the entire bodies were examined for worms. A total of 78 monkeys (43 males and 35 females) were exposed to infection and parasites were found in 29% of the females and 63% of males. In infections of 38 days or less worms were recovered from the testes of males and the pelt, carcass and lymph nodes of both sexes, but after 42 days of infection most worms were in the testes of males, and a few were recovered from lymph nodes and carcasses of females. Worms recovered at 8-11 days were third-stage, those found between 14 and 38 days fourth-stage, and ones found between 42 and 103 days were young adults. After 148 days most were adults and microfilariae were seen in the uteri of female worms at 160 days and later. The parasites continued to grow in size with time. Microfilariae were detected in the blood of nine monkeys between 8 and 18 months and the patent period varied from 5-21 months. Microfilarial densities were low and erratic, and periodicity could not be determined. The effectiveness of methods of administering infections and the value of various treatment regimens seem uncertain; monkey antilymphocytic sera, however, appeared to have some influence. Parasites were found in 36% of the Taiwan monkeys given the J strain and 54% of those given the K strain. A limited number of M. mulatta (3), M.irus (fascicularis) (3) and Aotus trivirgatus (4) were also given infective larvae and adult W. bancrofti were recovered from the testes of one male M. mulatta and one male M. irus; uterine microfilariae were found in one female worm from the latter monkey. A. trivirgatus were negative. Low numbers of infective larvae recovered from mosquitoes fed on patent monkeys were introduced intermittently into seven clean monkeys and one became microfilaremic between 11 and 17 months postinoculation.

A simple method to control Brugia timori by diethylcarbamazine administration

The results of mass treatment using 50 mg diethylcarbamazine per kg body-weight followed one year later by short term selective re-treatment in a highly endemic area of Brugia timori are described. The criteria for selection of re-treatment are simple and practical for use in rural areas. The microfilaria rate by finger prick decreased from 24% to 0 and by Nuclepore filtration from 30% to 2.5%. The disease rates were also affected favourably. 88% of persons receiving the drug reacted to treatment, this percentage slightly exceeding the total filarial infection rate (71%). The prevalence, onset, duration and nature of side reactions are briefly discussed and related to the presence of microfilaraemia and disease manifestations among the study population.