Ann Trop Med Parasitol
· 2010 Apr · PMID 20507698
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McMonnies' and Ocular Surface Disease Index (OSDI) questionnaires were used to estimate the prevalence of dry eye among 400 consecutive patients aged >40 years attending the ophthalmology outpatient department of the Lad...McMonnies' and Ocular Surface Disease Index (OSDI) questionnaires were used to estimate the prevalence of dry eye among 400 consecutive patients aged >40 years attending the ophthalmology outpatient department of the Lady Hardinge Medical College and associated Smt Sucheta Kriplani Hospital, in New Delhi, India. These estimates were then compared with the results of various clinical tests and examinations of the same patients, including Schirmer's tests, evaluations of tear-film breakup times and fluorescein staining of corneas. Although the overall prevalence of dry eye based on OSDI was 29.25%, there was considerable age- and gender-related variation in this parameter. Compared with the younger patients, those aged >or=80 years were more likely to have OSDI that were indicative of dry eye (41.2%), and the women investigated were more likely to have dry eye (as indicated by OSDI) than the men (27% v. 12%). Occupation, however, appeared to have no effect on the risk of dry eye (P=0.952). Grittiness was the commonest complaint reported. McMonnies' indices (MMI), OSDI and the values recorded in Schirmer's tests were all significantly and positively correlated with the probability of a clinical diagnosis of dry eye (P<0.001 for each). Only patients with a Schirmer's value of <8 mm showed fluorescein staining of the cornea (P<0.005). This appears to be the first report from India in which MMI and OSDI have been significantly correlated with the probability of a clinical diagnosis of dry eye. Although the subjects were recruited in an ophthalmology department and may not have been very representative of the general population of New Delhi, dry-eye syndrome is probably common in the study area and probably has a considerable socio-economic impact. The early detection and timely management of this syndrome is important, as they can help prevent long-term sequelae and sight-threatening complications.
Belardinelli M, Cocchi M, Raffaelli I
… +3 more, Guerra L, Tamburro A, Fausto AM
Ann Trop Med Parasitol
· 2010 Apr · PMID 20507697
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Leptoconops spp. are small midges, members of the family Ceratopogonidae, that are relatively widespread in wetlands with sandy or silty-clay soils, including many tourist sites. Although very few of the species are prov...Leptoconops spp. are small midges, members of the family Ceratopogonidae, that are relatively widespread in wetlands with sandy or silty-clay soils, including many tourist sites. Although very few of the species are proven vectors of pathogens, the blood-feeding females attack mammals, including humans, in large swarms and their painful bites may cause severe reactions, especially in children. Although Leptoconops spp. may limit the socio-economic development of an area, there are currently no effective methods for the control of their natural populations, and the repellents and netting used against mosquitoes are ineffective against these midges. The diurnal control of the adults with pesticides may have unacceptable impacts on non-target species, including humans, and be ineffective because the adult females can easily be carried, from untreated areas to treated, on the wind. In the present study, the use of a diflubenzuron-based insecticide against the larvae of Leptoconops (Holoconops) kerteszi Kieffer, 1908 - a sand-reproducing species that is widespread in certain coastal areas of the Italian province of Grosseto - was explored. In Grosseto, in summer, attacks by swarms of adult L. kerteszi create problems for the local people and the many tourists. The encouraging results of preliminary tests are discussed in relation to the potential use of diflubenzuron for the integrated control of L. kerteszi populations.
Imrie A, Roche C, Zhao Z
… +4 more, Bennett S, Laille M, Effler P, Cao-Lormeau VM
Ann Trop Med Parasitol
· 2010 Apr · PMID 20507696
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Full text
Dengue epidemic virulence is thought to be conferred by various factors, including the genotype of the virus involved. Increased or decreased epidemic virulence has been associated not only with the introduction of type-...Dengue epidemic virulence is thought to be conferred by various factors, including the genotype of the virus involved. Increased or decreased epidemic virulence has been associated not only with the introduction of type-2 (DENV-2) strains into the South Pacific, the Caribbean and South America, but also with newly emergent DENV-3 genotypes in Sri Lanka, and the year-to-year variation in the DENV-4 strains circulating in Puerto Rico. These observations indicate that there are inherent differences among viral genotypes in their capacity to induce severe disease, that is, their virulence potential. The present study involved a comparison of the complete genome sequences of DENV-1 viruses that had been isolated from cases of dengue fever (DF) or dengue haemorrhagic fever (DHF) that occurred in French Polynesia or Hawaii in 2001, when a virulent DHF-associated dengue epidemic was occurring throughout the Pacific region. Previous studies have identified putative virulence-associated motifs and substitutions in the DENV-2 genome, and the main aim of the present study was to identify similar changes in DENV-1 that may be associated with viral virulence. As no virulence determinants were seen, however, in any gene or untranslated region, it appears that genotype is not the sole determinant of virulence in DENV-1. Further studies, to compare DF- and DHF-associated strains of DENV-1 isolated from epidemics of variable virulence, in the same eco-biological context, are needed.
Ann Trop Med Parasitol
· 2010 Apr · PMID 20507695
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Sri Lanka is the newest reported focus of human leishmaniasis within the Indian subcontinent. Over the last 8 years, more than 2000 cases of cutaneous leishmaniasis (CL), apparently caused by Leishmania donovani (a speci...Sri Lanka is the newest reported focus of human leishmaniasis within the Indian subcontinent. Over the last 8 years, more than 2000 cases of cutaneous leishmaniasis (CL), apparently caused by Leishmania donovani (a species usually associated with the visceral form of the disease), have been passively identified in the country. The clinical profiles of 401 suspected cases of CL in Sri Lanka were recently explored and some of the cases' immunological responses were investigated, in antibody-detection assays based on the rk39 antigen. These studies were followed by cross-sectional surveys, involving active case detection, in three areas of Sri Lanka, two of them known to be at relatively high risk for CL, with the aims of estimating the local prevalences of the disease and identifying the main risk factors for its acquisition. This appears to be the first detailed report on the prevalence, risk factors and human serological response associated with human leishmaniasis in Sri Lanka. Although the data collected indicated that the transmission of the parasite causing CL was mostly outdoor (and possibly zoonotic) in the north of the country, most of the transmission in the south seemed to be peridomestic. The CL was found to affect a wide age range, in both male and female subjects. Curiously, the 24 cases of CL that were investigated in the rk39 assays gave negative results whereas the single cases of mucosal or visceral leishmaniasis that were studied were found positive for antibodies reacting with the rk39 antigen. More programmes of active case detection need to be launched across Sri Lanka before the true national burden posed by human leishmaniasis can be accurately evaluated. General awareness of leishmaniasis needs to be raised. Hopefully, continued research and disease monitoring will allow the effective control of leishmaniasis in Sri Lanka.
Ann Trop Med Parasitol
· 2010 Apr · PMID 20507694
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Plasmodium falciparum malaria is a major global health problem, responsible for up to 1 million deaths each year. Major efforts have been made to develop an effective vaccine against this disease, to reduce the associate...Plasmodium falciparum malaria is a major global health problem, responsible for up to 1 million deaths each year. Major efforts have been made to develop an effective vaccine against this disease, to reduce the associated morbidity and mortality. There has already been considerable progress, with the first vaccine against the pre-erythrocytic stages of P. falciparum now en route to licensure. There remains, however, a strong scientific rationale for the development of a highly effective additional vaccine component against the blood stages of the parasite, which could be deployed in conjunction with partially effective control measures against the pre-erythrocytic stages. Here, recent progress in the clinical development of blood-stage vaccines is reviewed, including methods of antigen selection, the limitations of in-vitro assays for selecting vaccines for clinical development, and the results of recently published clinical trials. This review seeks to summarize recent developments in our understanding of immunity to blood-stage parasites, as well as the relevant key advances made in vaccine technologies over the last decade. The future challenges that face this field of vaccine research are also described.
Boussaa S, Neffa M, Pesson B
… +1 more, Boumezzough A
Ann Trop Med Parasitol
· 2010 Mar · PMID 20406583
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Since the 1970s, Azilal and Ouarzazat have been the main foci for human cutaneous leishmaniasis (CL) in Morocco. The sandflies along the main roads linking these two foci to Marrakech city, which is considered to be an a...Since the 1970s, Azilal and Ouarzazat have been the main foci for human cutaneous leishmaniasis (CL) in Morocco. The sandflies along the main roads linking these two foci to Marrakech city, which is considered to be an area at risk of CL, were recently surveyed. Among the 872 sandflies collected, in June 2005, on the Marrakech-Ouarzazat road, Sergentomyia fallax was the most common species (36.1%), followed by Phlebotomus sergenti (21.1%), P. papatasi (14.2%), S. minuta (11.7%), P. longicuspis (5.5%), P. alexandri (5.4%), P. perniciosus (4.1%), P. ariasi (0.9%), S. africana (0.6%) and S. dreyfussi (0.3%). On the Marrakech-Azilal road, however, S. minuta was by far the most prevalent species (63.5% of the 1983 sandflies that were collected in August 2006), followed by S. fallax (12.9%), P. perniciosus (12.4%), P. sergenti (4.0%), P. longicuspis (3.0%), P. papatasi (2.8%), S. dreyfussi (1.1%) and P. alexandri (0.2%). The distribution of potential vectors along the two transects, according to altitude and bioclimate, was explored.
Ann Trop Med Parasitol
· 2010 Mar · PMID 20406582
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A new test for pathogenic Leptospira isolates, based on RAPD-PCR and high-resolution melt (HRM) analysis (which measures the melting temperature of amplicons in real time, using a fluorescent DNA-binding dye), has recent...A new test for pathogenic Leptospira isolates, based on RAPD-PCR and high-resolution melt (HRM) analysis (which measures the melting temperature of amplicons in real time, using a fluorescent DNA-binding dye), has recently been developed. A characteristic profile of the amplicons can be used to define serovars or detect genotypes. Ten serovars, of leptospires from the species Leptospira interrogans (serovars Australis, Robinsoni, Hardjo, Pomona, Zanoni, Copenhageni and Szwajizak), L. borgpetersenii (serovar Arborea), L. kirschneri (serovar Cynopteri) and L. weilii (serovar Celledoni), were typed against 13 previously published RAPD primers, using a real-time cycler (the Corbett Life Science RotorGene 6000) and the optimised reagents from a commercial kit (Quantace SensiMix). RAPD-HRM at specific temperatures generated defining amplicon melt profiles for each of the tested serovars. These profiles were evaluated as difference-curve graphs generated using the RotorGene software package, with a cut-off of at least 8 'U' (plus or minus). The results demonstrated that RAPD-HRM can be used to measure serovar diversity and establish identity, with a high degree of stability. The characterisation of Leptospira serotypes using a DNA-based methodology is now possible. As an objective and relatively inexpensive and rapid method of serovar identification, at least for cultured isolates, RAPD-HRM assays show convincing potential.
Gutiérrez-Cisneros MJ, Cogollos R, López-Vélez R
… +5 more, Martín-Rabadán P, Martínez-Ruiz R, Subirats M, Merino FJ, Fuentes I
Ann Trop Med Parasitol
· 2010 Mar · PMID 20406581
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In an effort to improve the diagnosis of intestinal amoebiasis, a real-time PCR has been used for the detection and differentiation of Entamoeba histolytica and E. dispar infections in African or South American immigrant...In an effort to improve the diagnosis of intestinal amoebiasis, a real-time PCR has been used for the detection and differentiation of Entamoeba histolytica and E. dispar infections in African or South American immigrants who live in Spain. Faecal samples from all of the 130 subjects had apparently been found to contain E. histolytica/E. dispar cysts by microscopical examination. Using the real-time PCR, E. histolytica DNA was detected in faecal samples from only 10 (7.7%) of the immigrants, with E. dispar DNA detected in the samples from another 117 (90.0%) of the subjects. The use of such PCR in the routine investigation of patients found positive for E. histolytica/E. dispar cysts (by microscopy) is recommended, especially in non-endemic areas.
da Silva RN, Amorim AC, Brandão RM
… +7 more, de Andrade HM, Yokoo M, Ribeiro ML, Bartchewsky W, Socorro-Silva A, de Castro JA, do Monte SJ
Ann Trop Med Parasitol
· 2010 Mar · PMID 20406580
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The performance of the less expensive SYBR-Green-based PCR assay, for quantifying Leishmania chagasi in smears of bone-marrow aspirates from naturally infected, mongrel dogs, was recently compared with that of a similar...The performance of the less expensive SYBR-Green-based PCR assay, for quantifying Leishmania chagasi in smears of bone-marrow aspirates from naturally infected, mongrel dogs, was recently compared with that of a similar PCR based on TaqMan chemistry. Aspirates were obtained from 36 infected dogs and examined for parasites by direct examination, culture, and quantitative PCR (qPCR) using specific primers (based on the parasite's kinetoplast DNA), DNA extracted from a smear, and either the SYBR-Green or TaqMan chemistries. Every aspirate smear was found PCR-positive for L. chagasi (whether the assay employed SYBR Green or TaqMan) but only 74% of the aspirates were found positive by culture and only 33% by direct, microscopical examination. There was no evidence of PCR inhibition when the DNA was collected from smears, and the parasite loads estimated using the SYBR-Green PCR were almost identical to those estimated using the TaqMan PCR (r=0.99). As a method for quantifying parasite loads in dogs infected with L. chagasi (and, probably, other mammals infected with other leishmanial parasites), PCR based on SYBR Green may therefore be an appropriate and inexpensive alternative to PCR based on TaqMan, and a reliable clinical tool.
Ishengoma DR, Derua YA, Rwegoshora RT
… +4 more, Tenu F, Massaga JJ, Mboera LE, Magesa SM
Ann Trop Med Parasitol
· 2010 Mar · PMID 20406579
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Early laboratory diagnosis is critical for the optimal management of human malaria, particularly following the introduction of relatively expensive, artemisinin-combination therapies (ACT). The performance of the laborat...Early laboratory diagnosis is critical for the optimal management of human malaria, particularly following the introduction of relatively expensive, artemisinin-combination therapies (ACT). The performance of the laboratories and the quality of malaria diagnosis have recently been assessed in 36 healthcare facilities in six districts of Tanzania. Questionnaires, checklists and observations were used to collect information on the availability and functional status of equipment as well as on laboratory personnel and their performance in malaria diagnosis. Together, the surveyed facilities had 112 laboratory staff [almost half (41.1%) of whom were laboratory assistants] and 57 microscopes. Twenty-seven (75.0%) of the healthcare facilities included in the survey had only one functional microscope each. Only seven (12.3%) of the assessed microscopes had been serviced in the previous 2 years. Of the 38 microscopists who were assessed, 24 (63.2%) were re-using microscope slides, 29 (73.5%) were producing bloodsmears of low quality, and 30 (79.0%) were using Field's stain. Although the facility microscopists gave similar results to experienced research microscopists when reading bloodsmears prepared by the survey team, using high-quality reagents (kappa=0.769), they appeared far less competent when reading smears stained using the reagents from the study laboratories (kappa=0.265-0.489). The quality of malaria diagnosis at healthcare facilities in Tanzania, which is generally poor (largely because of inadequate supplies of consumables and the limited skills of laboratory staff in the preparation of bloodsmears), urgently needs to be improved if the utilization of ACT is to be sustainable.
Koudou BG, Doumbia M, Janmohamed N
… +4 more, Tschannen AB, Tanner M, Hemingway J, Utzinger J
Ann Trop Med Parasitol
· 2010 Mar · PMID 20406578
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The seasonality of malaria transmission was investigated in two villages in central Côte d'Ivoire: one usually with irrigated rice farming (Zatta) and one without (Tiémélékro). Adult mosquitoes were collected, from Febru...The seasonality of malaria transmission was investigated in two villages in central Côte d'Ivoire: one usually with irrigated rice farming (Zatta) and one without (Tiémélékro). Adult mosquitoes were collected, from February 2002 to August 2005, inside and outside sentinel houses. In Tiémélékro, the biting rate of Anopheles gambiae s.s. showed a significant difference between the dry and rainy season only in 2003 (P<0.001). The corresponding rates for An. funestus s.s. showed significant seasonal differences in both 2002 and 2003 (P<0.001 for each year). In Zatta in 2003-2004, when irrigated rice farming was interrupted, there was no significant difference between the An. gambiae s.s. biting rates recorded in the dry and rainy seasons. In both 2002 and 2005, however, when irrigated rice farming was practised, the An. gambiae s.s. biting rate recorded in Zatta during the rainy season was significantly higher than that seen in the dry season (P<0.001 for each year). With just one exception (in Tiémélékro in 2005, the prevalence of Plasmodium infection in the An. funestus was significantly higher in the rainy season than in the dry season), no significant seasonal differences were seen in the prevalences of Plasmodium infection among the An. gambiae or An. funestus. In conclusion, although malaria transmission is quite stable in central Côte d'Ivoire throughout the year, it can be distinctly modified by irrigated rice farming.
Wickramarachchi T, Premaratne PH, Dias S
… +2 more, Handunnetti SM, Udagama-Randeniya PV
Ann Trop Med Parasitol
· 2010 Mar · PMID 20406577
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The presence of genetically different strains of malarial parasites in cases of human malaria is a severe drawback in the successful control of the disease. In Sri Lanka, although this species accounts for 60%-80% of all...The presence of genetically different strains of malarial parasites in cases of human malaria is a severe drawback in the successful control of the disease. In Sri Lanka, although this species accounts for 60%-80% of all of the cases of clinical malaria that occur each year, the genetic complexity of Plasmodium vivax on the island remains to be elucidated. In recent studies based on PCR-RFLP and the parasites' merozoite-surface-protein-3alpha locus, the genetic structure of 201 clinical isolates of P. vivax, from two malaria-endemic areas and a non-endemic area of the island, was investigated. Although the PCR only produced amplicons of three sizes [1900 (72.6%), 1500 (25.9%) and 1200 (1.5%) bp], the RFLP analysis based on HhaI or AluI digestion yielded 22 and 26 restriction patterns, respectively, with 51 combined patterns recorded. The distribution of the prominent PCR-RFLP haplotypes was area-specific. The probability that an investigated case had a multiple-clone infection (MCI) was higher among the cases from the endemic areas (20.0%) than among those from the non-endemic area (13.8%) but this difference was not statistically significant. Since 17 single-clone isolates produced only 11 different PCR-RFLP haplotypes but (after sequencing) 13 distinct nucleotide haplotypes, it is clear that the results of the PCR-RFLP were not revealing all of the diversity that existed at the nucleotide level. Four mass blood surveys in a malaria-endemic area demonstrated that seasonal changes in the prevalences of human infection with P. vivax may influence the occurrence of MCI.