How do people with chronic low back pain perceive specific and general exercise? A mixed methods survey.

PURPOSE: Exercise prescriptions for chronic low back pain (CLBP) often utilize reductionistic, trunk-focused exercise aimed at addressing proposed pain mechanisms. It is unknown if the use of these trunk-focused exercises imply beliefs to people with CLBP about the rationale for their use (e.g., etiology), even without concurrent biomedical narratives. This study aimed to explore people's perceptions of specific and general exercise without an accompanying narrative when experiencing CLBP. METHODS: An anonymous online survey was distributed. Mixed methods were utilized for analysis. Six-point Likert scales categorized people's beliefs about individual exercises. Open-ended questions were used to gather further beliefs which were then coded into themes. RESULTS: People with CLBP perceived specific exercise as more beneficial than general exercise. Eight themes and five subthemes were defined. A high volume of positive beliefs were centered around strengthening the low back and abdominal musculature, emphasizing the importance of correct technique. Negative beliefs were held against spinal flexion and external load. Both positive and negative beliefs were underpinned by spinal/pelvic stability being important as well as certain exercises being achievable or not. CONCLUSION: This study demonstrated that people with CLBP consider specific exercises to be more beneficial than general exercises for CLBP. Specific exercises irrespective of an accompanying narrative can imply meaning about the intent of an exercise. Understanding this requires practitioners to be mindful when prescribing and communicating exercise.

Conditioning of Leaf Detritus Modulates Density-Dependent Growth of Aedes triseriatus Larvae (Diptera: Culicidae).

Ration of food per capita of larval population is widely thought to limit mosquito production from container habitats, directly reflecting resource limitation. In this study, the importance of density-dependent resource limitation on larval Aedes triseriatus (Say) (Diptera: Culicidae) depended on the degree of microbial conditioning of senescent leaf detritus in surrogate tree holes. Density and ration strongly affected emergence, total female mass, and mean female mass of populations grown on leaves that had conditioned for 3 d, but had less impact when larval populations were grown on leaves that had conditioned for 1 mo. Ration per capita was a stronger predictor (50-94% of the variance) of all growth parameters measured for populations grown on leaves conditioned for 3 d compared with 1 mo (2-66% of variance), with the exception of development time. Larvae grew faster and to a larger body size on leaves conditioned for 3 d at low densities of larvae and a higher ration per capita. However, populations grown on leaves conditioned for 1 mo produced equal or more total mass and individuals of higher average mass than when grown on leaves conditioned for 3 d in treatments with low ration per capita. Well-conditioned detritus, representing the degree of microbial colonization of the organic material, must reflect the typical condition in tree holes with unconditioned leaves atypical. Therefore, results of this study suggest that experiments using well-conditioned leaves better estimate growth responses, including moderated density dependence and less importance of ration per capita, than experiments using unconditioned detritus.

Predicting West Nile Virus Infection Risk From the Synergistic Effects of Rainfall and Temperature.

Mosquito-based surveillance is a practical way to estimate the risk of transmission of West Nile virus (WNV) to people. Variations in temperature and precipitation play a role in driving mosquito infection rates and transmission of WNV, motivating efforts to predict infection rates based on prior weather conditions. Weather conditions and sequential patterns of meteorological events can have particularly important, but regionally distinctive, consequences for WNV transmission, with high temperatures and low precipitation often increasing WNV mosquito infection. Predictive models that incorporate weather can thus be used to provide early indications of the risk of WNV infection. The purpose of this study was first, to assess the ability of a previously published model of WNV mosquito infection to predict infection for an area within the region for which it was developed, and second, to improve the predictive ability of this model by incorporating new weather factors that may affect mosquito development. The legacy model captured the primary trends in mosquito infection, but it was improved considerably when calibrated with local mosquito infection rates. The use of interaction terms between precipitation and temperature improved model performance. Specifically, temperature had a stronger influence than rainfall, so that lower than average temperature greatly reduced the effect of low rainfall on increased infection rates. When rainfall was lower, high temperature had an even stronger positive impact on infection rates. The final model is practical, stable, and operationally valid for predicting West Nile virus infection rates in future weeks when calibrated with local data.

Divergent host preferences of above- and below-ground Culex pipiens mosquitoes and their hybrid offspring.

Culex pipiens form pipiens and Cx. pipiens form molestus (Diptera: Culicidae) belong to a cosmopolitan taxonomic group known as the Pipiens Assemblage. Hybridization between these forms is thought to contribute to human transmission of West Nile virus (WNV) in North America. Complementary choice and no-choice landing assays were developed to examine host acceptance by North American Cx. pipiens in the laboratory. Populations collected from above- and below-ground sites in suburban Chicago were identified as forms pipiens and molestus using a polymerase chain reaction-based assay. Avian and human host acceptance was then quantified for the two populations, as well as for their hybrid and backcross offspring. No-choice tests were used to demonstrate that both the pipiens and molestus forms were capable of feeding on human and avian hosts. Choice tests were used to demonstrate that form pipiens females were strongly avian-seeking; an individual's probability of accepting the chick host was 85%. Form molestus females were more likely to accept the human host (87%). Rates of host acceptance by F1 and backcross progeny were intermediate to those of their parents. The results suggest that host preferences in Cx. pipiens are genetically determined, and that ongoing hybridization between above- and below-ground populations is an important contributor to epizootic transmission of WNV in North America.

Application of a reverse dot blot DNA-DNA hydridization method to quantify host-feeding tendencies of two sibling species in the Anopheles gambiae complex.

A DNA-DNA hybridization method, reverse dot blot analysis (RDBA), was used to identify Anopheles gambiae s.s. and Anopheles arabiensis (Diptera: Culicidae) hosts. Of 299 blood-fed and semi-gravid An. gambiae s.l. collected from Kisian, Kenya, 244 individuals were identifiable to species; of these, 69.5% were An. arabiensis and 29.5% were An. gambiae s.s. Host identifications with RDBA were comparable with those of conventional polymerase chain reaction (PCR) followed by direct sequencing of amplicons of the vertebrate mitochondrial cytochrome b gene. Of the 174 amplicon-producing samples used to compare these two methods, 147 were identifiable by direct sequencing and 139 of these were identifiable by RDBA. Anopheles arabiensis bloodmeals were mostly (94.6%) bovine in origin, whereas An. gambiae s.s. fed upon humans more than 91.8% of the time. Tests by RDBA detected that two of 112 An. arabiensis contained blood from more than one host species, whereas PCR and direct sequencing did not. Recent use of insecticide-treated bednets in Kisian is likely to have caused the shift in the dominant vector species from An. gambiae s.s. to An. arabiensis. Reverse dot blot analysis provides an opportunity to study changes in host-feeding by members of the An. gambiae complex in response to the broadening distribution of vector control measures targeting host-selection behaviours.

Diversity of fish-associated flavobacteria of Michigan.

Flavobacteriosis poses a serious threat to wild and propagated fish stocks alike, accounting for more fish mortality in Michigan and its associated state fish hatcheries than all other pathogens combined. Although this consortium of fish diseases has primarily been attributed to Flavobacterium psychrophilum, F. columnare, and F. branchiophilum, herein we describe a diverse assemblage of Flavobacterium and Chryseobacterium spp. isolates recovered from diseased as well as apparently healthy wild, feral, and farmed fish of Michigan. Among 254 fish-associated flavobacterial isolates recovered from 21 fish species during 2003-2010, 211 were identified as Flavobacterium spp., whereas 43 were identified as Chryseobacterium spp. according to ribosomal RNA partial gene sequencing and phylogenetic analysis. Although F. psychrophilum and F. columnare were indeed associated with multiple fish mortality events, many previously uncharacterized flavobacteria were recovered from systemically infected fish showing overt signs of disease, and in vitro protease assays demonstrated that these isolates were highly proteolytic to multiple substrates that comprise host tissues. Indeed, the majority of the isolates either (1) were most similar to recently described fish-associated Flavobacterium and Chryseobacterium spp. that have never before been reported in North America (e.g., F. oncorhynchi, F. araucananum, C. viscerum, C. piscicola, and C. chaponense) or (2) did not cluster with any described species and most likely represent novel flavobacterial taxa. This study highlights the extreme diversity of flavobacteria that are potentially associated with flavobacteriosis in Michigan.

Pyrethroid resistance in Anopheles gambiae s.s. and Anopheles arabiensis in western Kenya: phenotypic, metabolic and target site characterizations of three populations.

Field and laboratory investigations revealed phenotypic, target site and metabolic resistance to permethrin in an Anopheles gambiae s.s. (Diptera: Culicidae) population in Bungoma District, a region in western Kenya in which malaria is endemic and rates of ownership of insecticide-treated bednets are high. The sensitivity of individual An. gambiae s.l. females as indicated in assays using World Health Organization (WHO) test kits demonstrated reduced mortality in response to permethrin, deltamethrin and bendiocarb. Estimated time to knock-down of 50% (KDT50 ) of the test population in Centers for Disease Control (CDC) bottle bioassays was significantly lengthened for the three insecticides compared with that in a susceptible control strain. Anopheles arabiensis from all three sites showed higher mortality to all three insecticides in the WHO susceptibility assays compared with the CDC bottle assays, in which they showed less sensitivity and longer KDT50 than the reference strain for permethrin and deltamethrin. Microplate assays revealed elevated activity of ß-esterases and oxidases, but not glutathione-S-transferase, in An. gambiae s.s. survivors exposed to permethrin in bottle bioassays compared with knocked down and unexposed individuals. No An. arabiensis showed elevated enzyme activity. The 1014S kdr allele was fixed in the Bungoma An. gambiae s.s. population and absent from An. arabiensis, whereas the 1014F kdr allele was absent from all samples of both species. Insecticide resistance could compromise vector control in Bungoma and could spread to other areas as coverage with longlasting insecticide-treated bednets increases.

Senescent leaf exudate increases mosquito survival and microbial activity.

We conducted experiments to evaluate the effects of soluble components in senescent leaf material on the growth and development of the eastern tree hole mosquito, Aedes triseriatus (Say). Oak leaves that were either leached for three days to remove the labile nutrient fraction, or were not leached, served as basal nutrient inputs in each experiment.Mosquito performance in microcosms containing leachate only was significantly worse compared with microcosms containing leaf material in combination with either leachate or water, indicating the importance of leaf substrates to mosquito production.Adult mosquito biomass, emergence, and development time were significantly higher in microcosms containing unleached leaves compared with leached leaf material. Additions of leachate to leached leaf treatments enhanced adult production, but not to the level observed in unleached leaf treatments.Filtered and unfiltered leachate added substantial nitrogen and phosphorus to microcosms and significantly affected mosquito growth responses. Bacterial productivity and abundance were also significantly affected by leachate additions and filtering.Taken together, these results suggest that while leaves decline with respect to nutritional value during decomposition, they remain important components of the habitat as substrates for microbial growth and mosquito feeding, particularly when nutrients (here, leachate) enter the system. Our results also illustrate the importance of soluble leaf material, which enhances mosquito production through effects on microbial community dynamics.

An acute trophic cascade among microorganisms in the tree hole ecosystem following removal of omnivorous mosquito larvae.

Results of two field experiments showed that selective removal of omnivorous mosquito larvae (Aedes triseriatus (Say)) functioning as top predators in the food web of a temperate, tree hole ecosystem resulted rapidly in increased abundance of flagellate and then ciliate populations. Flagellate density increased from <1 per ml to >103 per ml within 4 days of omnivore removal, followed shortly thereafter by an increase in ciliate density from <1 per ml to >102 per ml, after which flagellate density declined, and flagellate and ciliate densities stabilized. Rod-shaped bacteria increased slightly in density after removal of larval mosquitoes, then declined as protist density increased. Cocciform bacteria did not vary in density with these changes, thus the trophic cascade dampened at the remotest trophic level. Concomitant with the increase in protist densities, some bacteria formed elongated filaments >10 µm in length, likely an anti-predation, morphological response stimulated by suddenly intensified grazing as protozoan density rose. Results suggest that feeding by omnivorous mosquito larvae exhibited strong top-down effects on flagellate and ciliate populations, depressing them to below their equilibrium densities and nearly to extinction in tree hole ecosystems.

Toxicity of bloodmeals from ivermectin-treated cattle to Anopheles gambiae s.l.

Two anthelmintic drugs used as cattle dewormers, ivermectin and moxidectin, were tested for their lethal and sublethal effects on the malarial vectors Anopheles gambiae s.s. and An. arabiensis. In the laboratory, direct addition of ivermectin to bovine blood reduced the survivorship and fecundity of mosquitoes fed on the blood. The median lethal concentration (LC(50)) of ivermectin in the bloodmeal, for the laboratory populations of An. gambiae s.l., was 19.8 ppb. In the field, commercially available formulations containing ivermectin or moxidectin were injected into cattle at three times the recommended dose. Most (90%) of the An. gambiae s.s. that fed on the ivermectin-treated cattle within 2 weeks of treatment failed to survive more than 10 days post-bloodmeal. No eggs were deposited by An. gambiae s.s. that fed on ivermectin-treated cattle within 10 days of treatment. In contrast, the survivorship and egg production of the mosquitoes that fed on the moxidectin-treated cattle were no different from those feeding on untreated cattle. These results indicate that treatment of cattle with ivermectin could be used, as part of an integrated control programme, to reduce the zoophilic vector populations that contribute to the transmission of the parasites responsible for human malaria.

A supervised land cover classification of a western Kenya lowland endemic for human malaria: associations of land cover with larval Anopheles habitats.

BACKGROUND: A supervised land cover classification was developed from very high resolution IKONOS satellite data and extensive ground truth sampling of a ca. 10 sq km malaria-endemic lowland in western Kenya. The classification was then applied to an investigation of distribution of larval Anopheles habitats. The hypothesis was that the distribution and abundance of aquatic habitats of larvae of various species of mosquitoes in the genus Anopheles is associated with identifiable landscape features. RESULTS AND DISCUSSION: The classification resulted in 7 distinguishable land cover types, each with a distinguishable vegetation pattern, was highly accurate (89%, Kappa statistic = 0.86), and had a low rate of omission and commission errors. A total of 1,198 habitats and 19,776 Anopheles larvae of 9 species were quantified in samples from a rainy season, and 184 habitats and 582 larvae from a dry season. Anopheles gambiae s.l. was the dominant species complex (51% of total) and A. arabiensis the dominant species. Agricultural land covers (mature maize fields, newly cultivated fields, and pastured grasslands) were positively associated with presence of larval habitats, and were located relatively close to stream channels; whilst nonagricultural land covers (short shrubs, medium shrubs, tall shrubs, and bare soil around residences) were negatively associated with presence of larval habitats and were more distant from stream channels. Number of larval habitats declined exponentially with distance from streams. IKONOS imagery was not useful in direct detection of larval habitats because they were small and turbid (resembling bare soil), but was useful in localization of them through statistical associations with specific land covers. CONCLUSION: A supervised classification of land cover types in rural, lowland, western Kenya revealed a largely human-modified and fragmented landscape consisting of agricultural and domestic land uses. Within it, larval habitats of Anopheles vectors of human malaria were associated with certain land cover types, of largely agricultural origin, and close to streams. Knowledge of these associations can inform malaria control to gather information on potential larval habitats more efficiently than by field survey and can do so over large areas.

Designation of chemicals in terms of the locomotor responses they elicit from insects: an update of Dethier et al. (1960).

A scheme updating that of Dethier et al. (1960) (J. Econ. Entomol. 53: 134-136) for chemicals influencing insect locomotor behavior is introduced. Attractant, repellent, and arrestant retain their previous definitions. However, attractants or repellents are now recognized to operate both by kinetic and tactic mechanisms. Locomotor initiator is a new term for stimuli that activate normal levels of kinetic locomotion. Locomotor stimulant is reserved for activation of abnormally high kinetic locomotion, like that arising upon sublethal exposure to certain insecticides. The new terms engagent and disengagent apply to chemicals that, by their effects on locomotion, increase or decrease interaction with the source of stimulation, respectively. With these clarifications, insect behavioral terms unique to medical entomology but contradicting Dethier et al.'s classical scheme can be reconciled with the vocabulary of formal behavioral science.

Bacterial community structure in tree hole habitats of Ochlerotatus triseriatus: influences of larval feeding.

We investigated the bacterial community composition of tree holes in relation to the presence and absence of larvae of the mosquito Ochlerotatus triseriatus. Larvae were eliminated from a subset of natural tree holes with Bacillus thuringiensis serovar israelensis, and total bacterial numbers, slow- and fast-growing colony-forming units on minimal media, and 16S rRNA gene sequence data from water column and leaf material were obtained. Total bacterial counts did not change significantly with treatment; however, the number of slow-growing cultivable bacteria significantly increased in the absence of larvae. Sequence classifications and comparisons of sequence libraries using LIBSHUFF indicated that the elimination of larvae significantly altered bacterial community composition. Major groups apparently affected by larvae were Flavobacteriaceae, Rhodobacteraceae, Comamonadaceae, and Sphingomonadaceae. A clear dominance of Flavobacteriaceae in the water column after larval removal suggests members of this group are a major bacterial food source.

Characterization of strong promoters from an environmental Flavobacterium hibernum strain by using a green fluorescent protein-based reporter system.

We developed techniques for the genetic manipulation of Flavobacterium species and used it to characterize several promoters found in these bacteria. Our studies utilized Flavobacterium hibernum strain W22, an environmental strain we isolated from tree hole habitats of mosquito larvae. Plasmids from F. hibernum strain W22 were more efficiently (approximately 1,250-fold) transferred by electroporation into F. hibernum strain W22 than those isolated from Escherichia coli, thus indicating that an efficient restriction barrier exists between these species. The strong promoter, tac, functional in proteobacteria, did not function in Flavobacterium strains. Therefore, a promoter-trap plasmid, pSCH03, containing a promoterless gfpmut3 gene was constructed. A library of 9,000 clones containing chromosomal fragments of F. hibernum strain W22 in pSCH03 was screened for their ability to drive expression of the promoterless gfpmut3 gene. Twenty strong promoters were used for further study. The transcription start points were determined from seven promoter clones by the 5' rapid amplification of cDNA ends technique. Promoter consensus sequences from Flavobacterium were identified as TAnnTTTG and TTG, where n is any nucleotide, centered approximately 7 and 33 bp upstream of the transcription start site, respectively. A putative novel ribosome binding site consensus sequence is proposed as TAAAA by aligning the 20-bp regions upstream of the translational start site in 25 genes. Our primary results demonstrate that at least some promoter and ribosome binding site motifs of Flavobacterium strains are unusual within the bacterial domain and suggest an early evolutionary divergence of this bacterial group. The techniques presented here allow for more detailed genetics-based studies and analyses of Flavobacterium species in the environment.

Ovipositional site selection by Anopheles gambiae: influences of substrate moisture and texture.

The influence of substrate moisture (hydration) and grain size (texture) on oviposition was quantified in choice tests using Anopheles gambiae sensu stricto Giles (Diptera: Culicidae) laboratory strains and gravid An. gambiae sensu lato from a natural population in Western Kenya. A strong, positive correlation was found between moisture content and the degree of egg-laying, which peaked at saturation with standing water. Soil moisture quantified as surface conductivity, was measured with an electronic leaf-wetness sensor slightly modified from a unit available commercially. Although An. gambiae females were sensitive to measurable differences in substrate moisture, they distributed eggs on both fully hydrated and less hydrated substrates. In contrast, An. gambiae females showed little response to substrate texture: they oviposited with equal frequency on all silica substrates of eight particle size classes, ranging from small pebbles (850 microm diameter) to very fine grains (< 38 microm diameter), when all were moist. Female An. gambiae laid more eggs on dark than white substrates against a light background, but did not discriminate between moist, pulverized black soapstone and moist black Kenyan soil taken from typical An. gambiae larval habitats. We conclude that hydration and visual contrast are critical ovipositional site qualities for An. gambiae, but substrate texture is not.

Canine surveillance system for Lyme borreliosis in Wisconsin and northern Illinois: geographic distribution and risk factor analysis.

A seroprevalence survey for Borrelia burgdorferi was conducted among the healthy canine pet population in selected counties of Wisconsin and northern Illinois to determine the distribution of Lyme disease and associated risk factors. Information obtained for each dog included place of residence, Lyme disease vaccination status, history of travel and tick exposure, signalment, and medical history. Serum samples were screened by enzyme-linked immunosorbent assay and confirmed by an immunoblot procedure. Seroprevalence by county ranged 0-40%, with the highest estimates from west-central Wisconsin. The spatial pattern was significantly correlated with human incidence of Lyme disease and with abundance of the tick vector, Ixodes scapularis. A geographic information system (GIS) was used to integrate environmental data with the location of the residences of the dogs to determine environmental risk factors. Seropositivity among dogs was positively associated with increased tick exposure and time spent outdoors and negatively associated with vaccination against Lyme disease. Seropositivity was also associated with living in forested and urban areas, and on sandy, fertile soils. A canine surveillance system is a useful method for assessing the geographic distribution of Lyme disease, and in combination with a GIS, it can be effective in determining environmental factors associated with I. scapularis endemicity.

Stercorarial shedding and transtadial transmission of hepatitis B virus by common bed bugs (Hemiptera: Cimicidae).

Transtadial persistence and stercorarial shedding of hepatitis B virus (HBV) in common bed bugs, Cimex lectularius L., was studied by using experimental infectious blood feedings, infectious intrathoracic inoculations, and virus detection by polymerase chain reaction and Southern hybridization. Results showed that HBV persisted after an infectious blood meal in bed bug bodies for up to 35 d after the infectious blood meal. It was passed transtadially through one molt regardless of instar, was shed in fecal droplets for up to 35 d after the infectious blood meal, but was not passed transovarially. In bugs inoculated intrathoracically, HBV was detected for 21 d postinoculation. Previous studies detected the hepatitis B surface antigen found on both infectious and noninfectious particles in bed bugs. In this study, the presence of nucleic acids amplified from a conserved core region of the viral genome in bodies and feces of C. lectularius suggests that the HBV virus may be mechanically transmitted in feces or when bugs are crushed, during feeding.

Bacterial and fungal biomass responses to feeding by larval Aedes triseriatus (Diptera: Culicidae).

We investigated the effect of different densities (0, 20, or 40) of developing larval Aedes triseriatus (Say) on bacterial abundance, bacterial productivity, and leaf fungal biomass in a microcosm experiment. Larvae in the low-density treatment developed normally, but larvae at the high density were significantly slower to develop. Both bacterial abundance (direct microscopic counts) and bacterial productivity (3H-leucine incorporation rates) on leaf material were significantly lower in the presence of larvae. Bacterial abundance in the water column did not change significantly with treatment, but bacterial productivity varied with time and declined significantly at both larval densities. Bacteria on the walls and bottom of the containers also were less abundant and significantly less productive in the presence of larvae. Aside from presence/absence effects, there was no clear evidence that larval impacts were density-dependent. Leaf-associated fungal biomass, as measured by ergosterol levels, varied with time but was not significantly affected by any treatment, suggesting most fungal tissue was incorporated in the leaf matrix and unavailable to larvae. Based upon estimated biomass accrual and respiration of larvae, it appears that bacterial biomass and production were insufficient to account for carbon demands of growing larvae. Because fungal biomass and leaf mass likely contributed little to gross larval demands, other carbon sources (e.g., protozoa and extracellular microbial components) were probably used by larvae. Although apparently insufficient for all larval carbon demands, bacterial and leaf fungal biomass may be adequate for other larval nutritional needs (i.e., nitrogen and essential lipids).

Toxicity of ozonated animal manure to the house fly, Musca domestica.

Swine manure slurries were ozonated at a dosage of 1 g/L and tested for their toxicity to the house fly (Musca domestica). The observed toxicity of ozonated swine manure was consistent and independent of origin of the swine manure. A dose (dilution) response curve was performed. A 50% dilution in the ozonated swine manure slurry resulted in 90% reduction in toxicity. Neither the synthetic nor ozonated synthetic swine manure, both of which contained higher concentrations of formaldehyde and three other unidentified carbonyl compounds than the ozonated swine manure, were toxic to the flies. Ozonated swine manure slurry was centrifuged and passed through a 0.45-microm filter. The liquid phase was as toxic as the unfiltered slurry; as such, the toxicant appears to be present in liquid phase. Neither ammonia, hydrogen sulfide, formaldehyde, nor other simple aldehydes appeared to be the toxic agent. The toxic agent appears to be a polar chemical compound and is concentrated in the urine. Several possible compounds have been identified. The toxicity of untreated and ozonated manure slurries from different livestock was compared. Six animal manure slurries (beef and dairy cattle, horse, poultry, sheep, and swine) were ozonated (dosage of 1 g/L) and tested for toxicity to the house fly. Ozonated dairy cattle manure slurry showed 78% mortality after 72 h, whereas ozonated swine manure slurry achieved a 100% mortality rate in 48 h. Neither the unozonated dairy nor swine manure slurries, nor any of the other raw or ozonated manure slurries, were toxic to the flies.

Assessment of hepatitis B virus DNA and hepatitis C virus RNA in the common bedbug (Cimex lectularius L.) and kissing bug (Rodnius prolixus).

OBJECTIVE: Historical clinical studies suggest the potential for insect-borne transmission of human hepatitis viruses. Studies of hepatitis B virus (HBV) persistence in insects were performed before the advent of molecular techniques, and studies to assess possible insect-borne transmission of hepatitis viruses have not yet been performed. The aim of this study was to determine, using molecular techniques, whether HBV and hepatitis C virus (HCV) persist in and are excreted in the feces of the bedbug Cimex lectularius L. and kissing bug Rodnius prolixus after an infectious meal. METHODS: Blood-feeding insects from the insect order Hemiptera (Cimex lectularius L. and Rhodnius prolixus) were fed on blood from infected patients with high titers of HBV, HCV, and control uninfected patients. Insects and insect excrement were collected at weekly intervals and tested for HBV DNA and HCV RNA using the polymerase chain reaction. RESULTS: HBV DNA was detected in bedbugs and excrement up to 6 wk after feeding on an infectious meal. HBV DNA was also detected in most kissing bugs and excrement up to 2 wk after feeding. HCV RNA was not detected in bedbugs at any time after feeding. CONCLUSIONS: We did not detect HCV RNA in bedbugs after feeding on an infectious meal. Our data provide molecular evidence to suggest that HBV may persist in Hemiptera. Additional studies are ongoing to determine whether this viral persistence is capable of infection.