http://www.parasitesandvectors.com The latest research articles published by Parasites & Vectors 2012-02-02T00:00:00Z Background: A simple method called RAPLOA, to rapidly assess what proportion of people in a community are infected with L. loa and hence which communities are at high risk of severe adverse reactions following ivermectin treatment, was developed in Cameroon and Nigeria. The method needed further validation in other geographical and cultural contexts before its application in all endemic countries. The present study was designed to validate RAPLOA in two regions in the North East and South West of the Democratic Republic of Congo. Methods: In each study region, villages were selected from different bio-ecological zones in order to cover a wide range of loiasis endemicity. In each selected community, 80 persons above the age of 15 years were interviewed for a history of eye worm (migration of adult L.loa under the conjunctiva of the eye) and parasitologically examined for the presence and intensity of L.loa infection. In total, 8100 individuals from 99 villages were enrolled into the study. Results: The results confirmed the findings of the original RAPLOA study: i) the eye worm phenomenon was well-known in all endemic areas, ii) there was a clear relationship between the prevalence of eye worm history and the prevalence and intensity of L.loa microfilaraemia, and iii) using a threshold of 40%, the prevalence of eye worm history was a sensitive and specific indicator of high-risk communities. Conclusion: Following this successful validation, RAPLOA was recommended for the assessment of loiasis endemicity in areas targeted for ivermectin treatment by lymphatic filariasis and onchocerciasis control programmes. http://www.parasitesandvectors.com/content/5/1/25 Samuel Wanji Dowo Akotshi Maurice Mutro Tepage Floribert Tony Ukety Peter Diggle Jan Remme Parasites & Vectors 2012, null:25 2012-02-02T00:00:00Z doi:10.1186/1756-3305-5-25 This study was designed to validate RAPLOA in two regions in the North East and South West of the Democratic Republic of Congo. In each selected community, 80 people above the age of 15 years were interviewed for a history of eye and parasitologically examined for the presence and intensity of L. loa infection. The results confirmed the findings of the original RAPLOA study and the methodology is recommended for the assessment of loiasis endemicity in areas targeted for ivermectin treatment by lymphatic filariasis and onchocerciasis control programmes. Image: RAPLOA Interview; Field surveyor showing the picture of L. loa in the eye to a participant /content/figures/1756-3305-5-25-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 25 2012-02-02T00:00:00Z PDF Background: It is rare to find terrestrial nematode lineages parasitizing arthropods inhabiting the intertidal or littoral zone of the oceans. During an ecological study along the Oregon dunes, an allantonematid nematode (Tylenchomorpha: Allantonematidae) was discovered parasitizing the intertidal shore bug, Saldula laticollis (Reuter)(Hemiptera: Saldidae). This shore bug is adapted to an intertidal environment and can survive short periods of submergence during high tides. The present study describes the nematode parasite and discusses aspects of its development, ecology and evolution. Methods: Adults and last instar nymphs of S. laticollis (Hemiptera: Saldidae) were collected from the high intertidal zone among clumps of Juncus L. (Juncaceae) plants at Waldport, Oregon on October 3, 2011. The bugs were dissected in 1% saline solution and the nematodes killed in 1% Ringers solution and immediately fixed in 5% formalin (at 20o C). Third stage juveniles removed from infected hosts were maintained in 1% saline solution until they matured to the adult stage, molted and mated. Results: Halophilanema prolata n. gen., n. sp. (Nematoda: Allantonematidae) is described from last instar nymphs and adults of the intertidal bug, Saldula laticollis on the Oregon coast. The new genus can be distinguished from other genera in the Allantonematidae by a stylet lacking basal knobs in both sexes, an excretory pore located behind the nerve ring, ribbed spicules, a gubernaculum, the absence of a bursa and the elongate-tubular shape of the ovoviviparous parasitic females. Studies of the organogenesis of Halophilanema showed development to third stage juveniles in the uterus of parasitic females. Maturation to the free-living adults and mating occurred in the environment. The incidence of infection of S. laticollis ranged from 0 % to 85% depending on the microhabitat in the intertidal zone. Conclusions: Based on the habitat and morphological characters, it is proposed that Halophilanema adapted a parasitic existence fairly recently, evolutionarily speaking. It was probably a free-living intertidal or shore nematode that fed on microorganisms, especially fungi, in the intertidal habitat and became parasitic after saldids entered the environment. Halophilanema represents the first described nematode parasite of an intertidal insect. http://www.parasitesandvectors.com/content/5/1/24 George Poinar Parasites & Vectors 2012, null:24 2012-02-01T00:00:00Z doi:10.1186/1756-3305-5-24 Halophilanema prolata (Nematoda: Allantonematidae) is described from the intertidal bug, Saldula laticollis on the Oregon coast. Infection rates ranged from 0 % to 85% depending on the microhabitat in the intertidal zone. Image: Parasitic female and juvenile stages of Halophilanema prolata removed from the hemocoel of the intertidal bug, Saldula laticollis on the Oregon coast. /content/figures/1756-3305-5-24-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 24 2012-02-01T00:00:00Z PDF No abstract required for an Editorial http://www.parasitesandvectors.com/content/5/1/23 David Molyneux Parasites & Vectors 2012, null:23 2012-01-30T00:00:00Z doi:10.1186/1756-3305-5-23 /content/figures/1756-3305-5-23-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 23 2012-01-30T00:00:00Z PDF Background: Giardia duodenalis is a widespread parasite of mammalian species, including humans. The prevalence of this parasite in children residing in Portugal is currently unknown. This study intended to estimate G. duodenalis infection prevalence and identify possible associated risk factors in a healthy paediatric population living in the District of the Portuguese capital, Lisbon. Methods: Between February 2002 and October 2008, 844 children were randomly selected at healthcare centres while attending the national vaccination program. A stool sample and a questionnaire with socio-demographic data were collected from each child. Giardia infection was diagnosed by direct examination of stools and antigen detection by ELISA. Results: The population studied revealed a gender distribution of 52.8% male and 47.2% female. Age distribution was 47.4% between 0-5 years and 52.6% between 6-15 years.The prevalence of Giardia infection was 1.9% (16/844) when estimated by direct examination and raised to 6.8% (57/844) when ELISA results were added. The prevalence was higher among children aged 0-5 years (7.8%) than among older children (5.8%), and was similar among genders (6.9% in boys and 6.5% in girls). The following population-variables showed to be associated risk factors for G. duodenalis infection: mother's educational level (odds ratio (OR)=4.49; confidence interval (CI): 1.20-16.84), father's educational level (OR=12.26; CI:4.08-36.82), presence of Helicobacter pylori infection (OR=1.82; CI:1.05-3.15), living in houses with owned drainage system (OR=0.10; CI: 0.02-0.64) and reported household pet contact, especially with dogs (OR=0.53; CI: 0.31-0.93). Conclusion: Giardiasis prevalence in asymptomatic children residing in the region of Lisbon is high. Several risk factors were associated with Giardia prevalence and highlight the importance of parents' education and sanitation condition in the children's well being. The association between G. duodenalis and H. pylori seems an important issue deserving further investigation in order to promote prevention or treatment strategies. http://www.parasitesandvectors.com/content/5/1/22 Claudia Julio Anabela Vilares Monica Oleastro Idalina Ferreira Salome Gomes Lurdes Monteiro Baltazar Nunes Rogerio Tenreiro Helena Angelo Parasites & Vectors 2012, null:22 2012-01-27T00:00:00Z doi:10.1186/1756-3305-5-22 We investigated the prevalence of Giardia duodenalis infection and identified possible associated risk factors in a healthy paediatric population from Portugal. We highlight the high prevalence of G.duodenalis in these children, as well as the parents¿ education level as the main risk factor. Of interest, we also found an association between G. duodenalis and Helicobacter pylori infections. Image: Giardia duodenalis cysts stained by FICT. /content/figures/1756-3305-5-22-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 22 2012-01-27T00:00:00Z PDF Background: During the last decades two dams were constructed along the Senegal River. These intensified the practice of agriculture along the river valley basin. We conducted a study to assess malaria vector diversity, dynamics and malaria transmission in the area. Methods: A cross-sectional entomological study was performed in September 2008 in 20 villages of the middle Senegal River valley to evaluate the variations of Anopheles density according to local environment. A longitudinal study was performed, from October 2008 to January 2010, in 5 selected villages, to study seasonal variations of malaria transmission. Results: Among malaria vectors, 72.34% of specimens collected were An. arabiensis, 5.28% An. gambiae of the S molecular form, 3.26% M form, 12.90% An. pharoensis, 4.70% An. ziemanni, 1.48% An. funestus and 0.04% An. wellcomei. Anopheles density varied according to village location. It ranged from 0 to 21.4 Anopheles/room/day and was significantly correlated with the distance to the nearest ditch water but not to the river.Seasonal variations of Anopheles density and variety were observed with higher human biting rates during the rainy season (8.28 and 7.55 Anopheles bite/man/night in October 2008 and 2009 respectively). Transmission was low and limited to the rainy season (0.05 and 0.06 infected bite/man/night in October 2008 and 2009 respectively). During the rainy season, the endophagous rate was lower, the anthropophagic rate higher and L1014F kdr frequency higher. Conclusions: Malaria vectors are present at low-moderate density in the middle Senegal River basin with An. arabiensis as the predominant species. Other potential vectors are An. gambiae M and S form and An. funestus. Nonetheless, malaria transmission was extremely low and seasonal. http://www.parasitesandvectors.com/content/5/1/21 Mamadou Ndiath Jean-Biram Sarr Lobna Gaayeb Catherine Mazenot Seynabou Sougoufara Lassana Konate Franck Remoue Emmanuel Hermann Jean-Francois Trape Gilles Riveau Cheikh Sokhna Parasites & Vectors 2012, null:21 2012-01-23T00:00:00Z doi:10.1186/1756-3305-5-21 This study, conducted in the Middle Senegal River basin demonstrates that, although various malaria vectors are present all the year round in this region, malaria transmission remains low and limited to the short rainy season. Image: Senegal River in Guede village. /content/figures/1756-3305-5-21-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 21 2012-01-23T00:00:00Z PDF Background: Sandflies are vectors of Leishmania, the causative agent of leishmaniasis in mammalian hosts, including humans. The protozoan parasite is transmitted by the sandfly bite during salivation that occurs at the moment of blood feeding. The components of vector saliva include anticlotting and vasodilatory factors that facilitate blood flow and immunomodulatory factors that inhibit wound healing and quell the immune response. Not surprisingly, these factors also play important roles in the establishment of Leishmania infection. To date, the majority of knowledge that has been generated regarding the process of Leishmania infection, including L. infantum chagasi transmission has been gathered by using intradermal or subcutaneous inoculation of purified parasites.FindingsThis study presents the establishment of a transmission model of Leishmania infantum chagasi by the bite of Lutzomyia longipalpis, the vector of American visceral leishmaniasis. The parasites were successfully transmitted by infected sandfly bites to mice and hamsters, indicating that both animals are good experimental models. The L. infantum chagasi dose that was transmitted in each single bite ranged from 10 to 10, 000 parasites, but 75% of the sandflies transmitted less than 300 parasites. Conclusions: The strategy for initiating infection by sandfly bite of experimental animals facilitates future investigations into the complex and dynamic mechanisms of visceral leishmaniasis. It is important to elucidate the transmission mechanism of vector bites. This model represents a useful tool to study L. infantum chagasi infection transmitted by the vector. http://www.parasitesandvectors.com/content/5/1/20 Nagila Secundino Vanessa Freitas Carolina Monteiro Ana Clara Pires Bruna David Paulo Pimenta Parasites & Vectors 2012, null:20 2012-01-19T00:00:00Z doi:10.1186/1756-3305-5-20 We established a transmission model of Leishmania infantum chagasi by the bite of Lutzomyia longipalpis, the vector of American visceral leishmaniasis. The parasites were successfully transmitted to mice and hamsters indicating that both animals are good experimental models.Image: An infected sandfly biting a mouse ear (transmission experiment). Inset: The mouse ear after bite (red dot). /content/figures/1756-3305-5-20-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 20 2012-01-19T00:00:00Z PDF Background: Rickettsioses are among both the longest known and most recently recognized infectious diseases. Although new spotted fever group rickettsiae have been isolated in many parts of the world including China, Little is known about the epidemiology of Rickettsia pathogens in ticks from Xinjiang Autonomous Region of China. Methods: In an attempt to assess the potential risk of rickettsial infection after exposure to ticks in Xinjiang Uygur Autonomous Region of China, a total of 200 Dermacentor silvarum ticks collected in Xinyuan district were screened by polymerase chain reaction based on the outer membrane protein A gene. Results: 22 of the 200 specimens (11%) were found to be positive by PCR. Phylogenetic analysis of OmpA sequences identified two rickettsial species, Rickettsia raoultii (4.5%) and Rickettsia slovaca (6.5%). Conclusions: This study has reported the occurrence of Rickettsia raoultii and Rickettsia slovaca in Xinjiang Autonomous Region of China and suggests that Dermacentor silvarum could be involved in the transmission of rickettsial agents in China. Further studies on the characterization and culture of rickettsial species found in Dermacentor silvarum should be performed to further clarify this. Additionally, the screening of human specimens for rickettsial disease in this region will define the incidence of infection. http://www.parasitesandvectors.com/content/5/1/19 Zhan Tian Guang Liu Hui Shen Jun Xie Jin Luo Mei Tian Parasites & Vectors 2012, null:19 2012-01-19T00:00:00Z doi:10.1186/1756-3305-5-19 This study reported the occurrence of R. raoultii and R. slovaca in XUAR, China and suggests that D. silvarum could be involved in the transmission of rickettsial agents in China. Image: An stereomicroscope view of a Dermacentor silvarum adult female. /content/figures/1756-3305-5-19-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 19 2012-01-19T00:00:00Z PDF Taenia solium is a zoonotic cestode that causes taeniasis and cysticercosis in humans. The parasite is traditionally found in developing countries where undercooked pork is consumed under poor sanitary conditions and/or as part of traditional food cultures. However, the recent increase in international tourism and immigration is spreading the disease into non-endemic developed countries such as the United States. Although there has been concern that the number of cysticercosis cases is increasing in Japan, the current situation is not clear. This is largely because taeniasis and cysticercosis are not notifiable conditions in Japan and because there have been no comprehensive reviews of T. solium infections in Japan conducted in the last 15 years. Herein, we provide an overview of the status of T. solium infection in Japan over the past 35 years and point out the potential risks to Japanese society. http://www.parasitesandvectors.com/content/5/1/18 Tetsuya Yanagida Yasuhito Sako Minoru Nakao Kazuhiro Nakaya Akira Ito Parasites & Vectors 2012, null:18 2012-01-17T00:00:00Z doi:10.1186/1756-3305-5-18 This paper provides an overview of the status of T. solium infection in Japan over the past 35 years and point out the potential risks to Japanese society. Image: Egg of Taenia solium in feces. /content/figures/1756-3305-5-18-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 18 2012-01-17T00:00:00Z PDF Background: Chagas disease transmission risk is a function of the presence of triatomines in domestic habitats. Rhodnius ecuadoriensis is one of the main vectors implicated in transmission of Trypanosoma cruzi in Ecuador. This triatomine species is present in domestic, peridomestic and sylvatic habitats in the country. To determine the distribution of sylvatic populations of R. ecuadoriensis and the factors related to this distribution, triatomine searches were conducted between 2005 and 2009 in southern Ecuador. Methods: Manual triatomine searches were conducted by skilled bug collectors in 23 communities. Sylvatic searched sites were selected by a) directed sampling, where microhabitats were selected by the searchers and b) random sampling, where sampling points where randomly generated. Domiciliary triatomine searches were conducted using the one man-hour method. Natural trypanosome infection was determined by microscopic examination and PCR. Generalized linear models were used to test the effect of environmental factors on the presence of sylvatic triatomines. Results: In total, 1,923 sylvatic individuals were collected representing a sampling effort of 751 man-hours. Collected sylvatic triatomines were associated with mammal and bird nests. The 1,219 sampled nests presented an infestation index of 11.9%, a crowding of 13 bugs per infested nest, and a colonization of 80% of the nests. Triatomine abundance was significantly higher in squirrel (Sciurus stramineus) nests located above five meters from ground level and close to the houses. In addition, 8.5% of the 820 examined houses in the same localities were infested with triatomines. There was a significant correlation between R. ecuadoriensis infestation rates found in sylvatic and synanthropic environments within communities (p = 0.012). Parasitological analysis revealed that 64.7% and 15.7% of the sylvatic bugs examined (n = 300) were infected with Trypanosoma cruzi and T. rangeli respectively, and 8% of the bugs presented mixed infections. Conclusions: The wide distribution of sylvatic R. ecuadoriensis populations may jeopardize the effectiveness of control campaigns conducted to eliminate domestic populations of this species. Also, the high T. cruzi infection rates found in sylvatic R. ecuadoriensis populations in southern Ecuador could constitute a risk for house re-infestation and persistent long-term Chagas disease transmission in the region. http://www.parasitesandvectors.com/content/5/1/17 Mario Grijalva Victoria Suarez-Davalos Anita Villacis Sofia Ocana-Mayorga Olivier Dangles Parasites & Vectors 2012, null:17 2012-01-13T00:00:00Z doi:10.1186/1756-3305-5-17 Searches conducted in 23 localities in southern Ecuador show an abundance of sylvatic triatomines associated with squirrel, bird and rat nests, which may jeopardize the effectiveness of Chagas disease control campaigns. Image: Nests of the squirrel Sciurus stramineus are frequently infested with R. ecuadoriensis. /content/figures/1756-3305-5-17-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 17 2012-01-13T00:00:00Z PDF Background: RNA interference (RNAi) is an efficient reverse genetics technique for investigating gene function in eukaryotes. The method has been widely used in model organisms, such as the free-living nematode Caenorhabditis elegans, where it has been deployed in genome-wide high throughput screens to identify genes involved in many cellular and developmental processes. However, RNAi techniques have not translated efficiently to animal parasitic nematodes that afflict humans, livestock and companion animals across the globe, creating a dependency on data tentatively inferred from C. elegans. Results: We report improved and effective in vitro RNAi procedures we have developed using heterogeneous short interfering RNA (hsiRNA) mixtures that when coupled with optimized immunostaining techniques yield detailed analysis of cytological defects in the human parasitic nematode, Brugia malayi. The cellular disorganization observed in B. malayi embryos following RNAi targeting the genes encoding gamma-tubulin, and the polarity determinant protein, PAR-1 faithfully phenocopy the known defects associated with gene silencing of their C. elegans orthologs. Targeting the B. malayi cell junction protein, AJM-1 gave a similar but more severe phenotpye than that observed in C. elegans. Cellular phenotypes induced by our in vitro RNAi procedure can be observed by immunofluorescence in as little as one week. Conclusions: We observed cytological defects following RNAi targeting all seven B. malayi transcripts tested and the phenotypes mirror those documented for orthologous genes in the model organism C. elegans. This highlights the reliability, effectiveness and specificity of our RNAi and immunostaining procedures. We anticipate that these techniques will be widely applicable to other important animal parasitic nematodes, which have hitherto been mostly refractory to such genetic analysis. http://www.parasitesandvectors.com/content/5/1/16 Frederic Landmann Jeremy Foster Barton Slatko William Sullivan Parasites & Vectors 2012, null:16 2012-01-13T00:00:00Z doi:10.1186/1756-3305-5-16 This manuscript demonstrates the efficient use of heterogeneous short interfering RNA mixes for performing RNAi in the parasitic nematode Brugia malayi and immunofluorescence-based analysis of cellular phenotypes. Image: Defective 2 cell embryo of Brugia malayi following RNAi targeting the polarity-determining gene, par-1. /content/figures/1756-3305-5-16-toc.gif Parasites & Vectors 1756-3305 ${item.volume} 16 2012-01-13T00:00:00Z PDF