Freshwater leeches from Yemen

The occurrence of freshwater leeches in ten different wadis in Yemen was determined. Four species were recorded for the first time: Batracobdelloides tricarinatus, Helobdella conifera, Limnatis nilotica and Placobdelloides multistriatus. These species, typically found in Africa, are recorded in Yemen on the border of two biogeographical regions.     

An electrophoretic and morphological analysis of Labiostrongylus (Labiosimplex) bancrofti (Johnston & Mawson, 1939) (Nematoda: Cloacinidae), from macropodid marsupials,with the description of two new species

Allozyme electrophoresis was used to compare specimens of Labiostrongylus (Labiosimplex) bancrofti from two species of Australian macropodids, Macropus dorsalis and M. parryi, with a related species, L. (Labiomultiplex) uncinatus which also infests M. dorsalis. Each nematode was characterised genetically at 18 enzyme loci. The level of fixed genetic differences detected between L. (Ls.) bancrofti from M. parryi and M. dorsalis (83%) is equivalent to that when each is compared to the morphologically distinct species L. (Lm.) uncinatus (89–94%), demonstrating unequivocally that the taxon L. (Ls.) bancrofti represents at least two species, one in M. parryi and one in M. dorsalis. In addition, morphological evidence from additional specimens collected from M. parryi suggested the existence of a third sibling species in this group. All three species differ in the shape of the spicule tips; L. (Ls.) bancrofti has longer spicules than either of the two new species. L. (Ls.) quasibancrofti n. sp. has smaller cephalic papillae, larger oesophago-intestinal diverticula, a larger genital cone and a longer female tail than L. (Ls.) turnbulli n. sp. The taxon L. (Ls.) bancrofti consists, therefore, of three species, L. (Ls.) turnbulli in M. parryi, L. (Ls.) quasibancrofti in M. dorsalis, and L. (Ls.) bancrofti found in both host species, as well as in four species of rock wallabies.     

Identification and partial characterization of a parasite antigen in sera from humans infected with Wuchereria bancrofti

The purpose of this study was to identify and characterize soluble parasite antigens present in sera from humans infected with the filarial nematode Wuchereria bancrofti. Affinity chromatography and immunoblot methods were used to demonstrate a 200,000 m.w. circulating parasite antigen in sera from infected humans which corresponded to an antigen released by adult W. bancrofti during in vitro culture. Two monoclonal antibodies were produced to this antigen by immunizing mice with antigens from Dirofilaria immitis, a filarial parasite that is closely related to W. bancrofti, and screening cell fusion supernatants by enzyme immunoassay and counterimmunoelectrophoresis inhibition. The antibodies bound to a single repeated epitope (not phosphorylcholine) that was resistant to heat, acid, and protease treatments but sensitive to periodate oxidation. Immunoperoxidase studies showed that the epitope was concentrated in the cuticle and reproductive organs in D. immitis, and it was released in relatively large amounts by adult female D. immitis in vitro. The epitope is also present in antigens of other species of filarial and nonfilarial nematodes, but on the basis of preliminary studies, its presence in human serum appears to be specific for W. bancrofti infection.     

Placobdelloides tridens sp. n., a new species of glossiphoniid leech (Hirudinea: Rhynchobdellida) found feeding on captive Orlitia borneensis in Thailand,and an update to the host distribution of P. siamensis

A new glossiphoniid leech species, Placobdelloides tridens sp. n., is discovered on the Malayan Giant Turtle (Orlitia borneensis) at the Nakhon Ratchasima Zoo in Thailand. The morphological study of this new species revealed that it is distinguished from P. siamensis, a turtle leech species that can be found commonly in Thailand. Placobdelloides tridens presented the following diagnostic morphological characteristics: a pear-shaped and triannulate body, well-developed rod-like papillae on the dorsal surface, smooth posterior and anterior suckers with nominal pits inside, a single pair of dark contiguous eyes, light yellow-brown to greenish dorsal color, absence of median line, male and female gonopore separated by a single annulus and a unique trident shape at the tip of the crop ceca. The phylogenetic relationships of P. tridens sp. n., was clarified, and shown to be a sister clade to the P. siamensis and P. sirikanchanae clade. Furthermore, this is a new host record for P. siamensis, which was found on O. borneensis, Batagur affinis and B. borneoensis in the Khao Kheow Open Zoo, Chonburi, Thailand.

     

Age-grading and growth of Wuchereria bancrofti (Filariidea: Onchocercidae) larvae by growth measurements and its use for estimating blood-meal intervals of its Polynesian vector Aedes polynesiensis (Diptera: Culicidae)

Growth in length and width of Wuchereria bancrofti (Filariidea: Onchocercidae) larvae developing in its Polynesian vector Aedes polynesiensis (Diptera: Culicidae) was analysed using a mathematical approach to objectively extract patterns. L1 had a U-shaped growth in length, while widths followed an S-shaped function. L2 had an S-shaped growth in length and width. Growth in length of L3 was also S-shaped, while widths had an asymptotic size following a period of rapid shrinkage. The greatest difference between length and width was in stage 3 where the length was over 75 times greater than the width. The ratio of length to width was approximately 50 for microfilariae and only 10 for the L1 ('sausage') stage. Characteristic mean length (and width) were approximately 280(7) microm for microfilariae, approximately 181 microm for L1 at their smallest, and approximately 1584(22) microm for L3 infective larvae. There was a great increase in length during stage 2 from approximately 322(27) to approximately 982(31) microm. Stage duration decreased with increasing temperature while growth rate increased, giving steeper growth curves. There was no effect of temperature on size, except for L3, which were shorter when mosquitoes were reared at higher temperature. It appears that larval growth is a continuous process from microfilariae to the young L3 stage, and continuously modifies the larval parasite aspect, even within each stage. Thus, information on larval shape may be used as an age indicator and in some cases, may give an estimation on time elapsed since infection of the vector.An important demographic parameter used in most mathematical models describing transmission of parasites by insect vectors is the length of the gonotrophic cycle of the vector, i.e. the time interval between two successive blood-meals. Usual methods for computing such a parameter are based on mark-recapture techniques. However, reliable estimates need substantial capture rates, which are not always possible. This paper presents another approach in which marked mosquitoes are those naturally infected by W. bancrofti. For one mosquito, the time since infection is simply the age of the developing larval parasite. Our method first expresses the age of larval parasite as a fraction of total development time (from microfilariae entering the vector to L3 larvae) using a regression model based on measurements of the parasite's length and width. This fraction of development is then converted to a chronological age since infection, using a back-calculation procedure involving ambient temperatures and growth rates of W. bancrofti larvae in the vector. The method is applied to wild caught Ae. polynesiensis in French Polynesia to compute the length of the gonotrophic cycle. This mosquito species comes to bite approximately 3, 6-7 and 9 days after a first infectious blood-meal. Then the length of the gonotrophic cycle may be of 3-4 days.     

Endosymbiotic bacteria in the esophageal organ of glossiphoniid leeches

We characterized the intracellular symbiotic bacteria of the hematophagous glossiphoniid leeches Placobdelloides siamensis and a Parabdella sp. These leeches have a specialized structure called an "esophageal organ," the cells of which harbor bacterial symbionts. From the esophageal organ of each species, a 1.5-kb eubacterial 16S rRNA gene segment was amplified by PCR, cloned, and sequenced. Diagnostic PCR detected the symbiont in the esophageal organ and intestine. Phylogenetic analysis of the 16S rRNA gene(s) demonstrated that the symbionts from the leeches formed a monophyletic group in a well-defined clade containing endosymbiotic bacteria of plant sap-feeding insects in the gamma-subdivision of the Proteobacteria.The nucleotide compositions of the 16S rRNA gene from the leech symbionts were highly AT biased (53.7%).     

Change in composition of the Anopheles gambiae complex and its possible implications for the transmission of malaria and lymphatic filariasis in north-eastern Tanzania

ABSTRACT: BACKGROUND: A dramatic decline in the incidence of malaria due to Plasmodium falciparum infection in coastal East Africa has recently been reported to be paralleled (or even preceded) by an equally dramatic decline in malaria vector density, despite absence of organized vector control. As part of investigations into possible causes for the change in vector population density, the present study analysed the Anopheles gambiae s.l. sibling species composition in north-eastern Tanzania. METHODS: The study was in two parts. The first compared current species complex composition in freshly caught An. gambiae s.l. complex from three villages to the composition reported from previous studies carried out 2-4 decades ago in the same villages. The second took advantage of a sample of archived dried An. gambiae s.l. complex specimens collected regularly from a fourth study village since 2005. Both fresh and archived dried specimens were identified to sibling species of the An. gambiae s.l. complex by PCR. The same specimens were moreover examined for Plasmodium falciparum and Wuchereria bancrofti infection by PCR. RESULTS: As in earlier studies, An. gambiae s.s., Anopheles merus and Anopheles arabiensis were identified as sibling species found in the area. However, both study parts indicated a marked change in sibling species composition over time. From being by far the most abundant in the past An. gambiae s.s. was now the most rare, whereas An. arabiensis had changed from being the most rare to the most common. P. falciparum infection was rarely detected in the examined specimens (and only in An. arabiensis) whereas W. bancrofti infection was prevalent and detected in all three sibling species. CONCLUSION: The study indicates that a major shift in An. gambiae s.l. sibling species composition has taken place in the study area in recent years. Combined with the earlier reported decline in overall malaria vector density, the study suggests that this decline has been most marked for An. gambiae s.s., and least for An. arabiensis, leading to current predominance of the latter. Due to differences in biology and vectorial capacity of the An. gambiae s.l. complex the change in sibling species composition will have important implications for the epidemiology and control of malaria and lymphatic filariasis in the study area.     

Reproductive aspects of the mosquito Culex quinquefasciatus (Diptera:Culicidae) infected with Wuchereria bancrofti (Spirurida: Onchocercidae)

This study reports on the relationship between Wuchereria bancrofti infection and female body size, intake of blood and fecundity in the mosquito Culex quinquefasciatus, vector of this filarial parasite in Recife (Brazil). Adults from field collected larvae were infected via a membrane feeding procedure, using blood with parasitaemia ranging from 724-6,000 mf/ml. A positive correlation was observed between mosquito size (measured by wing length) and egg production in uninfected females. However, this relationship did not exist in W. bancrofti infected mosquitoes. This change is unlikely to be the result of changes in blood ingestion as no significant difference was found when infected and uninfected females were compared. Variation in egg production observed between trials could not be associated with parasite density in the blood. These results suggest infection with W. bancrofti may disrupt the relationship between mosquito size and egg production during the first gonotrophic cycle of C. quinquefasciatus such that fecundity is sometimes reduced. However, this overall affect is variable and many groups of mosquitoes do not respond in this way.     

Detection of Wuchereria bancrofti DNA in paired serum and urine samples using polymerase chain reaction-based systems

The Global Program for the Elimination of Lymphatic Filariasis (GPELF) aims to eliminate this disease by the year 2020. However, the development of more specific and sensitive tests is important for the success of the GPELF. The present study aimed to standardise polymerase chain reaction (PCR)-based systems for the diagnosis of filariasis in serum and urine. Twenty paired biological urine and serum samples from individuals already known to be positive for Wuchereria bancrofti were collected during the day. Conventional PCR and semi-nested PCR assays were optimised. The detection limit of the technique for purified W. bancrofti DNA extracted from adult worms was 10 fg for the internal systems (WbF/Wb2) and 0.1 fg by using semi-nested PCR. The specificity of the primers was confirmed experimentally by amplification of 1 ng of purified genomic DNA from other species of parasites. Evaluation of the paired urine and serum samples by the semi-nested PCR technique indicated only two of the 20 tested individuals were positive, whereas the simple internal PCR system (WbF/Wb2), which has highly promising performance, revealed that all the patients were positive using both samples. This study successfully demonstrated the possibility of using the PCR technique on urine for the diagnosis of W. bancrofti infection.     

Endosymbiotic Bacteria in the Esophageal Organ of Glossiphoniid Leeches

We characterized the intracellular symbiotic bacteria of the hematophagous glossiphoniid leeches Placobdelloides siamensis and a Parabdella sp. These leeches have a specialized structure called an “esophageal organ,” the cells of which harbor bacterial symbionts. From the esophageal organ of each species, a 1.5-kb eubacterial 16S rRNA gene segment was amplified by PCR, cloned, and sequenced. Diagnostic PCR detected the symbiont in the esophageal organ and intestine. Phylogenetic analysis of the 16S rRNA gene(s) demonstrated that the symbionts from the leeches formed a monophyletic group in a well-defined clade containing endosymbiotic bacteria of plant sap-feeding insects in the γ-subdivision of the Proteobacteria. The nucleotide compositions of the 16S rRNA gene from the leech symbionts were highly AT biased (53.7%).     

Development of loop-mediated isothermal amplification method for detecting Wuchereria bancrofti DNA in human blood and vector mosquitoes

We have developed loop-mediated isothermal amplification (LAMP) method to detect Wuchereria bancrofti DNA. The sensitivity and specificity of LAMP method were equivalent to those of PCR method which detects SspI repeat sequence in W. bancrofti genomic DNA: both methods detected one thousandth of W. bancrofti DNA from one microfilaria (Mf), and did not cross-react with DNAs of Brugia malayi, B. pahangi, Dirofilaria immitis, human and Culex quinquefasciatus. We also examined the sensitivity of LAMP using the mimic samples of patient's blood or blood-fed mosquitoes containing one W. bancrofti Mf per sample. The LAMP method was able to detect W. bancrofti DNA in 1000 μl of blood or in a pool of 60 mosquitoes, indicating its usefulness in detecting/monitoring W. bancrofti infection in humans and vector mosquitoes in endemic areas.     

Transmission efficiency of Culex quinquefasciatus and Aedes aegypti to Wuchereria bancrofti infection: an experimental study

Present study was undertaken to evaluate the suitability of natural (Culex quinquefasciatus) and experimental (Aedes aegypti) vectors for supporting the development of W. bancrofti larvae for onward transmission. Both the species permitted development of W. bancrofti mf to infective larvae (L3) within 11 to 13 days. The mf intake by both the species of mosquitoes was directly related to mf density in donor's blood. Culex exhibited higher L3 recovery than Aedes. In Aedes maximum percent L3 development occurred after ingesting 4 mf whereas Culex exhibited best establishment at an average mf intake of 11.5. Nevertheless wide variation in mf density in donor's blood did not significantly affect the larval establishment in Aedes mosquito while in Culex very high (> 400 mf/40 microliters) or low (< 50 mf/40 microliters) mf counts in donor's blood adversely affected the L3 recovery. The results reveals that A. aegypti has an edge over the natural vector, Culex in being a voracious feeder, their easy laboratory maintenance and better transmission potential.     

Helminth parasites of the western painted turtle, Chrysemys picta belli (Gray), including Neopolystoma elizabethae n. sp. (Monogenea: Polystomatidae), a parasite of the conjunctival sac

Neopolystoma elizabethae n. sp. is described from the conjunctival sac of the western painted turtle Chrysemys picta belli (Gray), from the Upper Peninsula of Michigan. This is the first species found in this location from chelonians in North America. The new species differs from all other species of Neopolystoma in possessing a circle of 8 genital spines that are recurved and possess a crescent-shaped base. Eight additional species of helminths were found in the 5 turtles examined in this study. All are common parasites of North American freshwater turtles. An additional species of Monogenea (Polystomoidespauli) was found in the oral cavity. Four species of Digenea (Eustomos chelydrae, Allassostomoides chelydrae, Spirorchis kirki, and Spirorchis parvus) and 3 species of Nematoda (Spiroxys contorta, Serpinema trispinosus, and Amphibiocapillaria serpentina) were also found. The following are reported from Michigan for the first time: P. pauli, S. kirki, and A. serpentina.     

Characterization of a muscle-associated antigen from Wuchereria bancrofti.

A recombinant clone, WbN1, isolated from a genomic expression library of Wuchereria bancrofti and showing restricted specificity at the DNA level (Southern and PCR analyses) for Wuchereria bancrofti and Brugia malayi has been previously described. Sequence analysis of WbN1 indicated that it had notable similarity to myosin. Further characterization using in situ hybridization has localized the mRNA in the muscle of the adult parasite and in the microfilariae. Rabbit polyclonal antiserum, raised against the recombinant WbN1 fused to the maltose-binding protein, recognized a 200-kDa polypeptide in immunoblots containing B. malayi antigen extracts. The same antibody also recognized myosin extracted from Brugia pahangi, Onchocerca volvulus, and Caenorhabditis elegans. Localization using the rabbit antiserum revealed the presence of the antigen in the adult muscle tissue and in the microfilariae; the same antibody inhibited the binding of a monoclonal antibody 28.2 (directed toward MHC B of C. elegans myosin) to the recombinant WbN1 antigen and also to purified C. elegans myosin. Based on homology data, structural location, competitive ELISA, and immunoblot we conclude that WbN1 is related to myosin or a similar myofibrillar protein.     

斑氏丝虫感染Scid小鼠模型的建立

采用人工感染法,对严重联合免疫缺陷小鼠(Scid 小鼠) 进行夜现周期性斑氏丝虫实验感染研究。结果表明,斑氏丝虫经人工感染后能在Scid 小鼠体内发育成熟并产生微丝蚴,且虫体回收率较高为6～30% ,平均14-8% 。感染的10 只小鼠均在外周血中检获出微丝蚴,及解剖收集到成虫,感染成功率高达100% 。作者认为Scid 小鼠由于T、B淋巴细胞功能缺如,不能产生相应的抗丝虫感染抗体,是一种易于感染成功、潜伏期短、微丝蚴密度及成虫回收率高的较理想的实验动物。     

An ant species of the genus <Emphasis Type="Italic">Pyramica</Emphasis> (Hymenoptera,Formicidae) new for the fauna of Russia and the Northern Caucasus

Data on the location of the ant Pyramica argiola (Emery 1869) in Russia, in the territory of the Northern Caucasus (Nalchik), are presented for the first time. The species was previously known from Transcaucasia. The species chorology and ecology and morphological peculiarities of individuals from the regional population are considered.     

A proposal to regard the former family Naididae as a subfamily within Tubificidae (Annelida, Clitellata)

A new species of Placobdelloides is described from crocodiles and river turtles in the Singapore Zoological Gardens. Placobdelloides stellapapillosa is three annulate, has one pair of eyes on somite I or II, six pairs of testisacs, two annuli between the gonopores, one post anal annulus, seven pairs of lobed crop caeca and 12–14 unique star-shaped papillae on the dorsal surface of each annulus. Star-shaped papillae on annulus a2 are typically larger and more pronounced than on annuli a1 and a3. Additional minute cone-shaped papillae may occur between the larger star-shaped papillae or may replace these papillae on annuli a1 and a3. Eggs and young (100–200) are attached by their posterior suckers directly to the ventral surface of the parent.     

Treatment of co-infection with bancroftian filariasis and onchocerciasis: a safety and efficacy study of albendazole with ivermectin compared to treatment of single infection with bancroftian filariasis

BACKGROUND: In order to use a combination of ivermectin and albendazole for the elimination of lymphatic filariasis, it is important to assess the potential risk of increased adverse events in individuals infected with both lymphatic filariasis and onchocerciasis. We compared the safety and efficacy of albendazole (400 mg) in combination with ivermectin (150 micrograms/kg), for the treatment of co-infections of Wuchereria bancrofti and Onchocerca volvulus with single infection of W. bancrofti. METHODS: The safety study on co-infections was a crossover, double blind design, while for the single infection of bancroftian filariasis an open design comparing two treatments was used. For co-infection, one group was allocated a single dose of ivermectin (150 micrograms/kg) plus albendazole (400 mg) (Group A). The other group received placebo (Group B). Five days later the treatment regime was reversed, with the Group A receiving placebo and Group B receiving treatment. For the single bancroftian filariasis infection, one group received a single dose of albendazole (400 mg) plus ivermectin (150 microg/kg) (Group C) while the other group received a single dose of albendazole (400 mg) alone (Group D). Blood and skin specimens were collected on admission day, day 0, and on days 2, 3, and 7 to assess drug safety and efficacy. Thereafter, blood and skin specimens were collected during the 12 months follow up for the assessment of drug efficacy. Study individuals were clinically monitored every six hours during the first 48 hours following treatment, and routine clinical examinations were performed during the hospitalisation period and follow-up. RESULTS: In individuals co-infected with bancroftian filariasis and onchocerciasis, treatment with ivermectin and albendazole was safe and tolerable. Physiological indices showed no differences between groups with co-infection (W. bancrofti and O. volvulus) or single infection (W. bancrofti). The frequency of adverse events in co-infected individuals was 63% (5/8, Group A, albendazole + ivermectin) and 57% (4/7, Group B, placebo) and of mild or moderate intensity. In single W. bancrofti infection the frequency of adverse events was 50% (6/12, Group C, albendazole + ivermectin) and 38% (5/13, Group D, albendazole) and of a similar intensity to those experienced with co-infection. There were no differences in adverse events between treatment groups. There was no significant difference in the reduction of microfilaraemia following treatment with albendazole and ivermectin in groups with single or co-infection. CONCLUSION: Our findings suggest that ivermectin plus albendazole is a safe and tolerable treatment for co-infection of bancroftian filariasis and onchocerciasis.