The present and future disease burden of hepatitis C virus infections with today's treatment paradigm - volume 3.

The total number, morbidity and mortality attributed to viraemic hepatitis C virus (HCV) infections change over time making it difficult to compare reported estimates from different years. Models were developed for 15 countries to quantify and characterize the viraemic population and forecast the changes in the infected population and the corresponding disease burden from 2014 to 2030. With the exception of Iceland, Iran, Latvia and Pakistan, the total number of viraemic HCV infections is expected to decline from 2014 to 2030, but the associated morbidity and mortality are expected to increase in all countries except for Japan and South Korea. In the latter two countries, mortality due to an ageing population will drive down prevalence, morbidity and mortality. On the other hand, both countries have already experienced a rapid increase in HCV-related mortality and morbidity. HCV-related morbidity and mortality are projected to increase between 2014 and 2030 in all other countries as result of an ageing HCV-infected population. Thus, although the total number of HCV countries is expected to decline in most countries studied, the associated disease burden is expected to increase. The current treatment paradigm is inadequate if large reductions in HCV-related morbidity and mortality are to be achieved.

Strategies to manage hepatitis C virus infection disease burden - volume 3.

The hepatitis C virus (HCV) epidemic was forecasted through 2030 for 15 countries in Europe, the Middle East and Asia, and the relative impact of two scenarios was considered: increased treatment efficacy while holding the annual number of treated patients constant and increased treatment efficacy and an increased annual number of treated patients. Increasing levels of diagnosis and treatment, in combination with improved treatment efficacy, were critical for achieving substantial reductions in disease burden. A 90% reduction in total HCV infections within 15 years is feasible in most countries studied, but it required a coordinated effort to introduce harm reduction programmes to reduce new infections, screening to identify those already infected and treatment with high cure rate therapies. This suggests that increased capacity for screening and treatment will be critical in many countries. Birth cohort screening is a helpful tool for maximizing resources. Among European countries, the majority of patients were born between 1940 and 1985. A wider range of birth cohorts was seen in the Middle East and Asia (between 1925 and 1995).

Historical epidemiology of hepatitis C virus (HCV) in select countries - volume 3.

Detailed, country-specific epidemiological data are needed to characterize the burden of chronic hepatitis C virus (HCV) infection around the world. With new treatment options available, policy makers and public health officials must reconsider national strategies for infection control. In this study of 15 countries, published and unpublished data on HCV prevalence, viraemia, genotype, age and gender distribution, liver transplants and diagnosis and treatment rates were gathered from the literature and validated by expert consensus in each country. Viraemic prevalence in this study ranged from 0.2% in Iran and Lebanon to 4.2% in Pakistan. The largest viraemic populations were in Pakistan (7 001 000 cases) and Indonesia (3 187 000 cases). Injection drug use (IDU) and a historically unsafe blood supply were major risk factors in most countries. Diagnosis, treatment and liver transplant rates varied widely between countries. However, comparison across countries was difficult as the number of cases changes over time. Access to reliable data on measures such as these is critical for the development of future strategies to manage the disease burden.

Zoonotic origin and transmission of Middle East respiratory syndrome coronavirus in the UAE.

Since the emergence of Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012, there have been a number of clusters of human-to-human transmission. These cases of human-to-human transmission involve close contact and have occurred primarily in healthcare settings, and they are suspected to result from repeated zoonotic introductions. In this study, we sequenced whole MERS-CoV genomes directly from respiratory samples collected from 23 confirmed MERS cases in the United Arab Emirates (UAE). These samples included cases from three nosocomial and three household clusters. The sequences were analysed for changes and relatedness with regard to the collected epidemiological data and other available MERS-CoV genomic data. Sequence analysis supports the epidemiological data within the clusters, and further, suggests that these clusters emerged independently. To understand how and when these clusters emerged, respiratory samples were taken from dromedary camels, a known host of MERS-CoV, in the same geographic regions as the human clusters. Middle East respiratory syndrome coronavirus genomes from six virus-positive animals were sequenced, and these genomes were nearly identical to those found in human patients from corresponding regions. These data demonstrate a genetic link for each of these clusters to a camel and support the hypothesis that human MERS-CoV diversity results from multiple zoonotic introductions.

UV crosslinked poly(acrylic acid): a simple method to bio-functionalize electrolyte-gated OFET biosensors.

A simple and time-saving wet method to endow the surface of organic semiconductor films with carboxyl functional groups is presented. A thin layer of poly(acrylic acid) (pAA) is spin-coated directly on the electronic channel of an electrolyte-gated organic FET (EGOFET) device and cross-linked by UV exposure without the need for any photo-initiator. The carboxyl functionalities are used to anchor phospholipid bilayers through the reaction with the amino-groups of phosphatidyl-ethanolamine (PE). By loading the membranes with phospholipids carrying specific functionalities, such a platform can be easily implemented with recognition elements. Here the case of biotinylated phospholipids that allow selective streptavidin electronic detection is described. The surface morphology and chemical composition are monitored using SEM and XPS, respectively, during the whole process of bio-functionalization. The electronic and sensing performance level of the EGOFET biosensing platform is also evaluated. Selective analyte (streptavidin) detection in the low pM range is achieved, this being orders of magnitude lower than the performance level obtained by the well assessed surface plasmon resonance assay reaching the nM level, at most.

Quantitative determination of free amino acids in the hemolymph of autogenous and anautogenous strains of Culex tarsalis (Diptera: Culicidae).

Autogenous and anautogenous strains were selected from the egg rafts of Culex tarsalis Coquillett collected from Coachella Valley, California. In autogenous (21-25 generations) and anautogenous (0-4 generations) strains used for hemolymph free amino acid analysis, the autogenous oviposition rates were 73.6-83.6% and 2.7-3.9%, the proportions of females undergoing autogenous ovarian development 120 h postemergence were 75.6 and 8.9%, respectively. To study the presence and quantities of free amino acids and explore their relationship to autogenous ovarian development, the 6 legs of females from both autogenous and anautogenous strains were removed at the coxo-femoral joints, and hemolymph was collected by centrifuging the bodies of 50-100 females. Proteins in the hemolymph were precipitated with 10% sulphosalicylic acid. On days 1, 4, 7, and 10 postemergence, a total of 17 free amino acids was found in females from the autogenous strain, and a total of 16 was found in females from the anautogenous strain in which asparagine (Asn) was absent. Comparisons of free amino acid concentrations between these 2 strains indicated that there were significant differences in total free amino acids and 13 individual free amino acids except Glu, Gln, Pro, and Met on day 1, total free amino acids and 14 individual free amino acids except Gln, Pro, and on day 4, and total free amino acids and 12 individual free amino acids except Asp, Glu, Gln, Pro, and Met on day 7 postemergence. There were no significant differences in the concentrations of individual and total free amino acids on day 10 postemergence. Female age affected free amino acid content in the autogenous strain, where total free amino acids and 14 individual free amino acid content in the autogenous strain, where total free amino acids and 14 individual free amino acids increased from day 1, peaked on day 4, declined on day 7, and declined further on day 10 postemergence. In the anautogenous strain, only total free amino acids and Ser, Gly, Ala, and Leu exhibited age-dependent changes in concentration, and the magnitude of changes in concentration was less than that in autogenous strain. Conclusively, autogenous ovarian development was the major reason for the changes in hemolymph free amino acid concentration postemergence. The current and previous findings indicate that the free amino acids, Arg, Gly, Ile, Leu, Lys, Phe, Ser, Thr, and Val putatively may be essential for vitellogenesis in mosquitoes.

Biological fitness of Culex quinquefasciatus (Diptera:Culicidae) susceptible and resistant to Bacillus sphaericus.

Biological fitness of laboratory and field-collected strains of southern house mosquito, Culex quinquefasciatus Say, susceptible and resistant (37- and 31-fold upon selection) to the microbial agent, Bacillus sphaericus, were compared in the absence of B. sphaericus. The resistant strains showed significantly lower fecundity and fertility, but they had significantly higher survival rates than the susceptible strains. The preadult stages from females of resistant strains developed at slightly faster rates than those of the susceptible strains, which could result in a shorter generation time. However, lower fecundity was likely to lead to overall lower population growth rates than in the susceptible strains. Data provided evidence that the resistant strains exhibited fitness disadvantages in the absence of B. sphaericus. We suggest that once resistance to B. sphaericus is detected in the field, its use should be discontinued until the mosquito population becomes susceptible again because of the decline in number of resistant individuals. A strategy of resistance management by rotation of insecticides is discussed.

Nutritional reserves, body weight, and starvation tolerance of autogenous and anautogenous strains of Culex tarsalis (Diptera:Culicidae).

The nutritional reserves and body weight of autogenous and anautogenous strains of Culex tarsalis Coquillett were determined for 4th instars, pupae, females, and males. Starvation tolerance and survivorship of adult females and males also were studied. The autogenous individuals contained significantly greater amounts of total lipids (except the total lipids in 4th instars), total carbohydrates, glycogen, and total proteins, which resulted in a heavier mean body weight of autogenous than anautogenous mosquitoes (except the fresh weight in pupae). Results of the body fluid coefficient determination were inconclusive. Nutritional reserves in the immature stages, especially the pupal stage, were significantly greater (except the total proteins in 4th instars and female adults) than those in the adult stage. There were no significant differences in median longevity between autogenous and anautogenous females, and between autogenous and anautogenous males, provided with distilled water alone after emergence. The median longevity of females and males was significantly different in both autogenous and anautogenous strains. Our findings strongly indicate a relationship between autogenous reproduction and differences in nutritional reserves of autogenous and anautogenous strains.

Comparative functional morphology of the mouth brushes of mosquito larvae (Diptera: Culicidae).

Structural and morphological features of the feeding brushes of fourth instars of four species of mosquitoes were studied using light and scanning electron microscopes. The fine structure of the elements of the lateral palatal brushes, anteromedian palatal brushes, mandibular brushes and combs, and maxillary brushes of each species was investigated and related to feeding behavior. The movement of the mouth brushes in living larvae was observed by stereomicroscopy under laboratory conditions. Mouth brush function and morphology varied among the species studied. The brushes of Culex quinquefasciatus Say, Cx. tarsalis Coquillett, and Aedes aegypti L. were more complex than those of Anopheles albimanus Wiedemann. The main role of the filaments of the lateral palatal brushes (LPB) was to generate and maintain water and particle flow around the larval head. In Ae. aegypti, most of the LPB filaments were provided with stout pointed teeth at the tips which were useful in the brushing of food material. In An. albimanus, the LPB filaments were simple and very closely packed and were used to stir the water surface film to direct the floating materials into the area of the mouth opening. The filaments of the anteromedian palatal brush (APBr) in the Culex species were branched. In Ae. aegypti, the APBr contained long bladelike filaments and short teethlike elements, whereas in An. albimanus, the APBr filaments were all long and bladelike. The morphological structure of the spicules and setae of the mandibular brushes and combs and the maxillary brushes are described. The main function of these brushes is to direct and concentrate particle flow.

Biological control of Culex mosquitoes (Diptera: Culicidae) by the tadpole shrimp, Triops longicaudatus (Notostraca: Triopsidae).

Laboratory oviposition choice tests and behavioral observations indicated that the activity of tadpole shrimp, Triops longicaudatus (LeConte), near the water surface deterred gravid Culex quinquefasciatus Say from ovipositing. In the cities of Oasis and Riverside, Calif., tadpole shrimp significantly reduced the abundance of immature mosquitoes (Cx. tarsalis Coquillett and Cx. quinquefasciatus) probably due to lowered oviposition rates, as well as tadpole shrimp predation. Generally, mosquito oviposition rates in field ponds with tadpole shrimp were lower than that of controls, except when tadpole shrimp were very young (4 d after flooding) or when their abundance had declined late in the flooding period. When analyzed by pond, tadpole shrimp size was correlated inversely with abundance; however, differences in size or abundance did not affect their capacity to reduce mosquito populations.

Factors influencing ingestion of particulate materials by mosquito larvae (Diptera: Culicidae).

Relative ingestion rates of mosquito larvae, as indicated by the number of substrate-filled gut segments per unit time, were determined for Culex tarsalis Coquillett, Aedes aetypti L., and Anopheles albimanus Wiedemann. Among the three species, Ae. aegypti larvae were the most rapid feeders. F50 (median time for complete repletion of 50% of the larvae) was 61, 42, and 100 min for the three species feeding on a wheat flour suspension, respectively. Food particles with nutritive values (dried yeast, wheat flour, fishmeal, or dried blood) were ingested faster than inert particles (kaolin, talc, chalk, or charcoal). The addition of aqueous yeast extracts containing phagostimulants accelerated the ingestion of inert particles. Increasing the concentration of inert particles did not increase ingestion rates. Larval age, water temperature, and starvation, but not larval density, influenced rates of ingestion. Younger instars were more rapid feeders than older instars. First instars of the three species filled their guts with wheat flour approximately two times faster than fourth instars. Increasing water temperature from 18 to 31 degrees C accelerated wheat flour ingestion by fourth instars of Cx. tarsalis, Ae. aegypti, and An. albimanus by factors of 1.9, 1.5, and 1.7, respectively. After starvation for 12 h, fourth instars of Cx. tarsalis and Ae. aegypti increased ingestion of wheat flour about 1.6 and 1.8 times, respectively. In contrast, starvation of An. albimanus larvae for the same period resulted in decreased wheat flour ingestion by 2.2 times when compared with unstarved larvae. These results indicare that, in addition to the chemical factors associated with the food substances, the physiological and environmatal conditions of the larvae play an important role in regulating the ingestion rate of suspended particles by mosquito larvae.

Ecology of Culex tarsalis (Diptera: Culicidae): factors influencing larval abundance in mesocosms in southern California.

Colonization and succession of mosquitoes and macroinvertebrate predators were studied in 30-m2 ponds (mesocosms) during summer and fall 1987. Larval abundance of Cx. tarsalis Coquillette was lower during the hot, summer months than during the fall. In all studies, larval populations declined markedly 2-3 wk after habitat flooding. Although predator abundances differed in these studies, sometimes by an order of magnitude, the common predators colonized mesocosms in the following order: Triops, hydrophilid beetle larvae, dytiscid beetle larvae, mesoveliids, dragonfly and damselfly naiads, and notonectids. The similarity of the colonization phenologies probably resulted from the vagility of the adult insects and species-specific developmental rates. Stepwise multiple regression was used to identify factors potentially affecting larval mosquito populations. For most studies, coleopteran larvae were related inversely to per capita change in the entire larval population and the third- and fourth-instar subpopulation (i.e., large coleopteran larval populations were associated with large declines in the Cx. trasalis larval population). Maximum water temperatures and pond age (days after flooding) also were identified as significant factors affecting larval abundance and per capita change of mosquitoes. Potentially lethal water temperatures (greater than or equal to 35 degrees C) occurred during the summer; however, the declines in larval abundance of Cx. tarsalis were not restricted to (or obviously associated with) periods of high water temperature. Our results indicated that predation by coleopteran larvae and factor(s) associated with pond age, such as mosquito ovipositional preferences, significantly affected Cx. tarsalis larval populations.

Effect of water and artificial saliva on mechanical properties of some denture-base materials.

Two artificial saliva samples selected on the basis of being chemically and physically similar to natural saliva were used as saturation media so that we could investigate their effects on mechanical properties of four denture-base materials, and the results were compared with the effect of water on the same materials. Diffusion coefficients in the more viscous saliva were different from those in water but, in general, mechanical properties were similarly affected in all liquids, indicating that the aqueous phase of the artificial medium was a major factor influencing the results.

Effect of drying period and soil moisture on egg hatch of the tadpole shrimp (Notostraca: Triopsidae).

Tadpole shrimp (Triops spp.) are potential biological control agents against larval mosquitoes in temporary ponds and flood-irrigated fields. In some rice field situations, however, they may become pests that uproot and eat young rice plants. In cursory observations, it has been reported that tadpole shrimp eggs do not readily hatch on flooding when the soil or substrate containing eggs is moist before flooding. The relationship between drying (moisture content) of soil and tadpole shrimp hatch was determined in studies conducted in mesocosms at the University of California Aquatic and Vector Control Research facilities at Riverside and at Oasis in the Coachella Valley of southern California. In laboratory hatching trials, an increase in hatch of Triops longicaudatus (LeConte) with declining soil moisture content was demonstrated (t = 8.4, P less than 0.001; r2 = 0.76). In field trials in mesocosms at Riverside, egg hatch increased with increased drying period and declining soil moisture content (G = 29.8, P less than 0.01). No hatch of eggs occurred after 3 d of drying, when soil moisture content was high, but a high level of hatching occurred after 7 and 14 d of drying, when soil moisture declined to low levels. At Oasis, soil moisture did not decrease with drying time because of porous soil and capillary action of water from adjacent flooded mesocosms and thick vegetation covering the pond bottoms. Therefore, hatch rates at Oasis were not associated with the length of the drying period (G = 35, P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

The future of insect growth regulators in vector control.

Insect growth regulators (IGRs) are diverse groups of chemical compounds that are highly active against larvae of mosquitoes and other insects. The IGRs in general have a good margin of safety to most nontarget biota including invertebrates, fish, birds, and other wildlife. They are also relatively safe to man and domestic animals. The IGR compounds do not induce quick mortality in the preimaginal stages treated. Mortality occurs many days later after treatment. This is indeed a desirable feature of a control agent because larvae of mosquitoes and other vectors are an important source of food for fish and wildlife. On account of these advantages of IGRs and the high level of activity against target species, it is likely that IGRs will play an important role in vector control programs in the future.

Mosquito control then, now, and in the future.

This is a memorial lecture honoring the late Professor Stanley B. Freeborn of the University of California. In the spirit of his life-long academic and research interests in mosquitoes and mosquito-borne diseases, I am presenting here the evolution of vector control technology, especially that pertaining to mosquitoes and mosquito-borne diseases during the 20th century. Vector control technology in the first half of this century was relatively simple, utilizing source reduction, larvivorous fish, petroleum hydrocarbon oils, and some simple synthetic and botanical materials. During the 2nd half of this century, however, various classes of synthetic organic chemicals, improved petroleum oil formulations, insect growth regulators, synthetic pyrethroids, and microbial control agents were developed and employed in mosquito control and control of other disease-vectoring insects. Among these groups of control agents, petroleum oil formulations have endured to be used through the whole century. It is likely that petroleum oil formulations, insect growth regulators, and microbial control agents will provide the main thrust against vectors at least during the first quarter of the 21st century. It is also possible that effective tools through the development of vaccines and molecular entomology techniques might become available for the control of vectors and vector-borne diseases during this period of the 21st century.

Efficacy of new insect growth regulators against mosquito larvae in dairy wastewater lagoons.

Four new insect growth regulators (IGRs) and a slow-release formulation of a currently-used IGR were evaluated for the control of Culex peus and Cx. quinquefasciatus in dairy wastewater lagoons. The IGR AC-291898 (CME 13406) proved highly efficacious, producing 100% control for one week and about 98% control for two weeks at the rate of 0.05 lb AI/acre (0.056 kg/ha). The IGR XRD-473 produced similar results at this rate. The effective rate of these two compounds seems to be in the range of 0.05 to 0.1 lb AI/acre (0.056-0.11 kg/ha). A granular formulation of S-31183 (0.5 G) applied at 0.05 lb AI/acre (0.056 kg/ha) yielded mediocre reduction whereas fenoxycarb EC 1 at up to 0.25 lb AI/acre (0.28 kg/ha) and methoprene 4% slow release pellets at up to 1.0 lb AI/acre (1.12 kg/ha) produced little or no control of Culex in the dairy wastewater lagoons. These compounds need to be applied at higher rates or suitable formulations will have to be developed to achieve satisfactory control.

Prey-size selection by Triops longicaudatus (Notostraca: Triopsidae) feeding on immature stages of Culex quinquefasciatus.

The tadpole shrimp, Triops longicaudatus, was found to be a size-dependent predator of Culex quinquefasciatus larvae in the laboratory. However, changes in tadpole shrimp size were accompanied by changes in prey-size preference: larger-sized predators consumed an increasing proportion of larger prey items. Very large tadpole shrimp may be nonselective predators of this mosquito species. Quantified behavioral observations indicated that while second instar mosquito larvae were encountered significantly less frequently than were fourth instar larvae or pupae, they were captured at significantly greater rates and with shorter handling times. It is hypothesized that prey vulnerability has an important influence on tadpole shrimp prey size "preferences."

Ovicidal activity of neem products (azadirachtin) against Culex tarsalis and Culex quinquefasciatus (Diptera: Culicidae).

Bioactive compounds contained in the seed kernel and other parts of the neem tree (Azadirachta indica A. Juss) have been found to show insecticidal activities and other effects in many species of insects. These activities include antifeedancy, growth regulation, fecundity suppression, male sterility, oviposition repellency, changes in biological fitness such as loss of flying ability, immunodepression, enzyme inhibition, splitting of biological rhythms, and so forth. We investigated the ovicidal effects of various formulations of azadrirachtin (AZ) against the mosquitoes Culex tarsalis Coquillett and Culex quinquefasciatus Say. The formulations tested were wettable powder Azad WP10, emulsifiable concentrate Azad EC4.5, and technically pure AZ. The ovicidal activity of the test neem products was influenced by concentration of AZ, age of the egg rafts, and age of the neem preparations. Other factors such as formulation and mosquito species were also involved in the degree of ovicidal activity. When the egg rafts were deposited directly in fresh neem suspension and left there for 4 h before transfer to untreated water, 1 ppm of AZ produced almost 100% mortality in eggs. When egg rafts aged for 0, 4, 8, 12, and 24 h were exposed to 10 ppm neem suspensions for 36 h, the ovicidal activity was only attained in the egg rafts deposited directly (0 h old) in the neem suspension, not in those with ages of 4-24 h. On aging, depending on the formulations and mosquito species, the neem suspensions at 1 ppm completely lost ovicidal activity within 7-20 days. The egg rafts of Cx. quinquefasciatus were more susceptible to the test neem products than those of Cx. tarsalis. The formulated neem products were more persistent and effective than the technical AZ. The wettable powder (WP) formulation was slightly more persistent and effective than the emulsifiable concentrate (EC). The ovicidal activity of the neem products against mosquitoes from the current research clearly demonstrated the potential of neem products as possible ovicides against Culex mosquitoes.

Influence of tadpole shrimp, Triops longicaudatus (Notostraca:Triopsidae), stocking rate on Culex tarsalis development in experimental field microcosms.

The effectiveness of 5 tadpole shrimp (TPS) stocking rates to reduce cohorts of Culex tarsalis was studied in field microcosms (0.81-m2). Larval/pupal abundance in microcosms containing greater than 5 TPS/m2 was significantly (P less than 0.05) lower than that of controls lacking tadpole shrimp due to predation. Adult mosquito abundances captured in emergence units above the microcosms stocked with tadpole shrimp were significantly (P less than 0.05) lower than that of controls at rates greater than or equal to 10 TPS/m2. Tadpole shrimp growth during 17 days of this study was inversely proportional to their stocking rate, and a linear relationship between size and stocking rate was plotted. Tadpole shrimp stocking rates also influenced rate of mosquito development, causing significantly (P less than 0.05) shorter periods for 50% emergence where shrimp were present when compared with that of controls. Adult male Cx. tarsalis emerged significantly earlier then females in microcosms stocked at 5 TPS/m2, while no significant (P greater than 0.05) differences were detected between the sexes at the remaining predator stocking rates.