G. I. Parra and K. Y. Green

Background: Rapid, accurate and high-throughput identification of vector arthropods is of paramount importance in surveillance programmes that are becoming more common due to the changing geographic occurrence and extent of many arthropod-borne diseases. Protein profiling by MALDI-TOF mass spectrometry fulfils these requirements for identification, and reference databases have recently been established for several vector taxa, mostly with specimens from laboratory colonies. Methods: We established and validated a reference database containing 20 phlebotomine sand fly (Diptera: Psychodidae, Phlebotominae) species by using specimens from colonies or field-collections that had been stored for various periods of time. Results: Identical biomarker mass patterns (‘superspectra’) were obtained with colony- or field-derived specimens of the same species. In the validation study, high quality spectra (i.e. more than 30 evaluable masses) were obtained with all fresh insects from colonies, and with 55/59 insects deep-frozen (liquid nitrogen/-80 °C) for up to 25 years. In contrast, only 36/52 specimens stored in ethanol could be identified. This resulted in an overall sensitivity of 87% (140/161); specificity was 100%. Duration of storage impaired data counts in the high mass range, and thus cluster analyses of closely related specimens might reflect their storage conditions rather than phenotypic distinctness. A major drawback of MALDI-TOF MS is the restricted availability of in-house databases and the fact that mass spectrometers from 2 companies (Bruker, Shimadzu) are widely being used. We have analysed fingerprints of phlebotomine sand flies obtained by automatic routine procedure on a Bruker instrument by using our database and the software established on a Shimadzu system. The sensitivity with 312 specimens from 8 sand fly species from laboratory colonies when evaluating only high quality spectra was 98.3%; the specificity was 100%. The corresponding diagnostic values with 55 field-collected specimens from 4 species were 94.7% and 97.4%, respectively. Conclusions: A centralized high-quality database (created by expert taxonomists and experienced users of mass spectrometers) that is easily amenable to customer-oriented identification services is a highly desirable resource. As shown in the present work, spectra obtained from different specimens with different instruments can be analysed using a centralized database, which should be available in the near future via an online platform in a cost-efficient manner.

Background: Triatomine bugs are blood-sucking insects, vectors of Chagas disease. Despite their importance, their oviposition behavior has received relatively little attention. Some triatomines including Rhodnius prolixus stick their eggs to a substrate. It is known that mechanical cues stimulate oviposition in this species. However, it is not clear if chemical signals play a role in this behavior. We studied the role of host cues, including host odor, in the oviposition behavior of the triatomine R. prolixus. Methods: Tests were carried out in an experimental arena and stimuli consisted of a mouse or hen feathers. The number of eggs laid and the position of those eggs with respect to the stimulus source were recorded. Data were analyzed using the Mann-Whitney and Kruskal-Wallis tests. Results: Both a mouse and hen feathers stimulated oviposition. In addition, hen feathers evoked a particular spatial distribution of eggs that was not observed in the case of mouse. Conclusions: We propose that volatile chemical cues from the host play a role in the oviposition behavior of triatomines that stick their eggs. Thus, host odor would stimulate and spatially guide oviposition.

C. Reusken et al.

Background: Toxocara canis is a nematode that parasitizes dogs, while humans are paratenic hosts. When humans are infected the migrating larvae damage the liver, lungs and even the nervous system. Larva migrans diagnosis is based on immunological techniques; however, the commercial immunodiagnostic kits detect anti-T. canis antibodies which may cross-react with other parasites, mainly nematodes with extra-intestinal migration. Moreover, antibodies do not necessarily reflect an active infection; so detection and quantification of circulating antigens may provide appropriate and timely information for treatment, which prevents irreversible damage. Here we report the standardization of a monoclonal antibody based antigen capture ELISA to diagnose human toxocariasis without cross-reaction. Methods: We developed anti-T. canis polyclonal antibodies in rabbits and a monoclonal antibody in mouse which did not cross-react with 15 antigens from several parasites. The sandwich ELISA standardization was performed using sera from mice experimentally infected. We tested the method using 29 positive and 58 negative human sera previously typified with a commercial kit, which detects antibodies. Results: Only 5.0 μg/mL and 10 μg/mL polyclonal antibodies and monoclonal antibody, respectively, were needed in the sandwich ELISA standardization, detecting since 440 pg/mL larva antigens. Nine out of 29 antibody-positive sera were also positive for antigens and no false positive were found. Taking the antibody kit as the reference standard, the sensibility and specificity of the antigen test were 31% and 100%, respectively. Conclusions: With these tools we established a detection threshold as low as 440 pg/mL antigen. Monoclonal antibody is specific, and did not cross-react with antigens from other parasites. Detection of circulating antigens helps provide appropriate and timely treatment and prevents irreversible damage.

Background: In general, there was a large reduction in the occurrence of cases of Chagas disease in the last decades in Brazil. However, despite all of these efforts, there have been various reports of persistent reinfestations of T. sordida in a large part of the state of Minas Gerais, for reasons still little investigated. Thus, this purpose of this study was to characterize the deltamethrin susceptibility profile of peridomestic T. sordida populations from North of Minas Gerais – Brazil. Methods: Susceptibility to deltamethrin was assessed in seventeen peridomestic populations of T. sordida from North region of Minas Gerais, Brazil. Serial dilutions of deltamethrin in acetone (0.2 μL) were topically applied in first instar nymphs (F1, five days old, fasting, weight 1.2 ± 0.2 mg). Dose response results were analyzed with POLO program, determining the lethal doses, slope and resistance ratios (RR). Results: Susceptibility profile characterization of T. sordida populations revealed resistance ratios (RR50) ranging from 2.50 to 7.27. Conclusions: In fact, we know very little about the real impact of the resistance ratios obtained in the laboratory bioassays on the effectiveness of the vector control activities in the field. Thus, we prefer to refer to the populations with RR > 5 as populations with altered susceptibility. For these populations, the realization of laboratory and field trials, simultaneous and complementary, permitting the evaluation of both, is recommended.

Background: Newly recognized endemic foci for human babesiosis include Europe, where Ixodes ricinus, a vector for several species of Babesia, is the most commonly identified tick. Vector-based surveillance provides an early warning system for the emergence of human babesiosis, which is likely to be under-reported at emerging sites. In the present study, we set out to screen I. ricinus collected from Danish domestic dogs for Babesia, in order to identify whether humans in Denmark are exposed to the parasite.FindingsA total of 661 ticks (Ixodes spp.) were collected from 345 Danish domestic dogs during April-September 2011 and pooled, one sample per dog. DNA was extracted from each sample and examined by PCR and sequencing for Rickettsia spp., Borrelia burgdorferi sensu lato, Bartonella spp., Francisella tularensis, Candidatus Neoehrlichia mikurensis, and Babesia spp. In total, 34% of the samples were positive for tick-borne microorganisms potentially pathogenic to humans: Rickettsia spp. were detected in 16% of the pools, with 79% being R. helvetica. Borrelia burgdorferi sensu lato was found in 15%, with the main species identified as Borrelia afzelii (39%). Likewise, 8% of the samples were positive for Babesia spp. (Babesia microti, 82%; Babesia venatorum (‘EU1’), 18%). Lastly, 1% of the samples tested positive for Candidatus Neoehrlichia mikurensis, and 0.6% for Bartonella spp. No ticks were found to be infected with Francisella tularensis. Conclusions: Our data are in support of endemic occurrence of potentially zoonotic Babesia in Denmark and confirms I. ricinus as a vector of multiple pathogens of public health concern.

Background: Focal screening and treatment (FSAT) of malaria infections has recently been introduced in Peru to overcome the inherent limitations of passive case detection (PCD) and further decrease the malaria burden. Here, we used a relatively straightforward mathematical model to assess the potential of FSAT as elimination strategy for Plasmodium falciparum malaria in the Peruvian Amazon Region. Methods Methods: A baseline model was developed to simulate a scenario with seasonal malaria transmission and the effect of PCD and treatment of symptomatic infections on the P. falciparum malaria transmission in a low endemic area of the Peruvian Amazon. The model was then adjusted to simulate intervention scenarios for predicting the long term additional impact of FSAT on P. falciparum malaria prevalence and incidence. Model parameterization was done using data from a cohort study in a rural Amazonian community as well as published transmission parameters from previous studies in similar areas. The effect of FSAT timing and frequency, using either microscopy or a supposed field PCR, was assessed on both predicted incidence and prevalence rates. Results: The intervention model indicated that the addition of FSAT to PCD significantly reduced the predicted P. falciparum incidence and prevalence. The strongest reduction was observed when three consecutive FSAT were implemented at the beginning of the low transmission season, and if malaria diagnosis was done with PCR. Repeated interventions for consecutive years (10 years with microscopy or 5 years with PCR), would allow reaching near to zero incidence and prevalence rates. Conclusions Conclusions: The addition of FSAT interventions to PCD may enable to reach P. falciparum elimination levels in low endemic areas of the Amazon Region, yet the progression rates to those levels may vary substantially according to the operational criteria used for the intervention.

C. L. Althaus and M. Salathé

S. E. Smith et al.

Background: The pathogenesis of S. mansoni infection involves chronic inflammatory responses to parasite eggs which can be associated with a characteristic periportal fibrosis (PPF) and the progression to severe hepatosplenic disease. The effects of HIV-1 co-infection and the influence of CD4+ cell numbers on these clinical manifestations of chronic S. mansoni are not known. To understand the effects of HIV-1 co-infection on these morbidities, we examined S. mansoni ultrasound-detectable morbidities in relation to HIV-1 infection and CD4+ cell counts, and other factors in fishing communities where the two infections are present. Methods: Ultrasonographical examination was conducted during a cross-sectional study of 1,671 (aged 21–55 years) individuals in North-Western Tanzania. Blood samples were obtained for HIV-1 screening and CD4+ cell quantification. A single stool sample was examined for S. mansoni eggs using the Kato-Katz technique. A questionnaire was used to collect socio-demographic-economic information. Results: The prevalence of PPF (grade C-F) was 13.79% and 15.01% for the HIV-1 infected and non-infected individuals (P = 0.72). Male gender (P< 0.001), age group 21–30 years (P< 0.028) and, residential time of 11–20 (P< 0.01) and ≥21 years (P< 0.01) were associated with PPF in S. mansoni infected individuals. The height-adjusted measurements of the left liver lobe were significantly larger in HIV-1/S. mansoni co-infected compared to S. mansoni only-infected individuals (t = −2.0702, P< 0.039). Predictors of the height-adjusted measurements of the left liver lobe and spleen were age, male gender, malaria infection, fishing occupation, village of residence and heavy intensity of S. mansoni infection. After accounting for these factors, neither HIV-1 infection nor CD4+ cell counts predicted PPF, hepatosplenomegaly, measurements of the liver or spleen. Height-adjusted ultrasound measurements of the left liver lobe did not correlate with the CD4+ cells counts in co-infected individuals (r = −0.16, P = 0.084). Conclusion: S. mansoni-related PPF, liver and spleen enlargement are prevalent in the study population. The intensity of S. mansoni infection was associated with the enlargement of liver, spleen and hepatosplenomegaly. The PPF grades observed were similar in both HIV-1/S. mansoni co-infected and in those only infected with S. mansoni. There was no evidence that HIV-1 infection or CD4+ cells counts were associated with these S. mansoni morbidities.

H. Shen et al.

T. E. Taha et al.

B. Breedlove

L. Xin et al.

S. Cribbs

K. Okada et al.

C. McKnight

S. Lhomme et al.