Control techniques for Culicoides biting midges and their application in the U.K. and northwestern Palaearctic

The recent emergence of bluetongue virus (Reoviridae: Orbivirus) (BTV) in northern Europe, for the first time in recorded history, has led to an urgent need for methods to control the disease caused by this virus and the midges that spread it. This paper reviews various methods of vector control that have been employed elsewhere and assesses their likely efficacy for controlling vectors of BTV in northern Europe. Methods of controlling Culicoides spp. (Diptera: Ceratopogonidae) have included: (a) application of insecticides and pathogens to habitats where larvae develop; (b) environmental interventions to remove larval breeding sites; (c) controlling adult midges by treating either resting sites, such as animal housing, or host animals with insecticides; (d) housing livestock in screened buildings, and (e) using repellents or host kairomones to lure and kill adult midges. The major vectors of BTV in northern Europe are species from the Culicoides obsoletus (Meigen) and Culicoides pulicaris (L.) groups, for which there are scant data on breeding habits, resting behaviour and host-oriented responses. Consequently, there is little information on which to base a rational strategy for controlling midges or for predicting the likely impact of interventions. However, data extrapolated from the results of vector control operations conducted elsewhere, combined with some assessment of how acceptable or not different methods may be within northern Europe, indicate that the treatment of livestock and animal housing with pyrethroids, the use of midge-proofed stabling for viraemic or high-value animals and the promotion of good farm practice to at least partially eliminate local breeding sites are the best options currently available. Research to assess and improve the efficacy of these methods is required and, in the longer term, efforts should be made to develop better bait systems for monitoring and, possibly, controlling midges. All these studies will need better methods of analysing the ecology and behaviour of midges in the field than are currently in use. The paucity of control options and basic knowledge serve to warn us that we must be better prepared for the possible emergence of other midge-borne diseases, particularly African horse sickness.

Variant Creutzfeldt-Jakob [corrected] disease: the second case in Portugal and in the same geographical region

We present the second variant Creutzfeldt-Jacob patient in the same district of northwest Portugal as was previously reported. A 14-year-old previously healthy girl had unexplained pain in the left leg, as well as psychiatric disturbances. This was shortly followed by progressive cognitive impairment, ataxia and generalised choreoatethosis. Neuropsychological assessment revealed severe frontal and medial temporal dysfunction, the posterior cortices being spared. An electroencephalogram was normal. CSF 14.3.3 protein was slightly positive. Magnetic resonance imaging showed the "hockey stick sign" and hyperintensities in the periaquedutal grey matter and in the right parietal cortex, the last with restriction to water molecule movement. SPECT revealed perfusion defects in the left frontotemporal and right parietal regions. PRNP gene sequencing showed no mutations, the patient being homozygous to methionine in codon 129. Five months after onset, immunocytochemical and immunoblotting analysis confirmed deposition of prion protein and a PrP4t electrophoretic pattern. The patient never travelled outside Portugal or received blood transfusions. She had surgical herniorrhaphy in 1998 (when catgut was used) and 2003. This is the second case in Portugal in a 2-year period and 20 km apart from each other, with no known common exposure apart from ingestion of cow meat. We discuss these case peculiarities and underline its epidemiological significance.

Culicoides biting midges at the National Zoological Gardens of South Africa

Culicoides biting midges (Diptera: Ceratopogonidae) are responsible for the transmission of a large number of pathogens to livestock and wild animals. In this study the presence of the genus, using light traps based at four different sites within the National Zoological Gardens of South Africa, was investigated during 2002-2004. In total, 37 species were recorded, including large numbers of Culicoides imicola Kieffer, 1913, which is responsible for the transmission of economically important arboviruses in South Africa, Europe, Middle and Far East. These results are discussed with reference to the wider Culicoides fauna in the Onderstepoort area of South Africa, their vector competence as well as biosecurity at the National Zoological Gardens.

Development and initial evaluation of a real-time RT-PCR assay to detect bluetongue virus genome segment 1

Since 1998, multiple strains of bluetongue virus (BTV), belonging to six different serotypes (types 1, 2, 4, 8, 9 and 16) have caused outbreaks of disease in Europe, causing one of the largest epizootics of bluetongue ever recorded, with the deaths of >1.8 million animals (mainly sheep). The persistence and continuing spread of BTV in Europe and elsewhere highlights the importance of sensitive and reliable diagnostic assay systems that can be used to rapidly identify infected animals, helping to combat spread of the virus and disease. BTV has a genome composed of 10 linear segments of dsRNA. We describe a real-time RT-PCR assay that targets the highly conserved genome segment 1 (encoding the viral polymerase--VP1) that can be used to detect all of the 24 serotypes, as well as geographic variants (different topotypes) within individual serotypes of BTV. After an initial evaluation using 132 BTV samples including representatives of all 24 BTV serotypes, this assay was used by the European Community Reference Laboratory (CRL) at IAH Pirbright to confirm the negative status of 2,255 animals imported to the UK from regions that were considered to be at risk during the 2006 outbreak of BTV-8 in Northern Europe. All of these animals were also negative by competition ELISA to detect BTV specific antibodies and none of them developed clinical signs of infection. These studies have demonstrated the value of the assay for the rapid screening of field samples.

Clinical signs and pathology shown by British sheep and cattle infected with bluetongue virus serotype 8 derived from the 2006 outbreak in northern Europe

Four poll Dorset sheep and four Holstein-Friesian cattle were infected with the northern European strain of bluetongue virus (BTV), BTV-8, to assess its pathogenicity in UK breeds. The time course of infection was monitored in both species by using real-time reverse transcriptase-PCR (RT-PCR), conventional RT-PCR and serology. Two of the sheep developed severe clinical signs that would have been fatal in the field; the other two were moderately and mildly ill, respectively. The cattle were clinically unaffected, but had high levels of viral RNA in their bloodstream. Real-time RT-PCR detected viral RNA as early as one day after infection in the cattle and three days after infection in the sheep. Antibodies against BTV were detected by six days after infection in the sheep and eight days after infection in the cattle. Postmortem examinations revealed pathology in the cattle that was more severe than suggested by the mild clinical signs, but the pathological and clinical findings in the sheep were more consistent.

Culicoides biting midges at the National Zoological Gardens of South Africa : research communication

Culicoides biting midges (Diptera: Ceratopogonidae) are responsible for the transmission of a large number of pathogens to livestock and wild animals. In this study the presence of the genus, using light traps based at four different sites within the National Zoological Gardens of South Africa, was investigated during 2002-2004. In total, 37 species were recorded, including large numbers of Culicoides imicola Kieffer, 1913, which is responsible for the transmission of economically important arboviruses in South Africa, Europe, Middle and Far East. These results are discussed with reference to the wider Culicoides fauna in the Onderstepoort area of South Africa, their vector competence as well as biosecurity at the National Zoological Gardens.

Quantification of PCV2 capsid transcript in peripheral blood mononuclear cells (PBMCs) in vitro

The presence of PCV2 DNA or spliced capsid mRNA (Cap mRNA) for viral replication was assessed following addition of PCV2 to resting or concanavalin A (ConA) stimulated peripheral blood mononuclear cells (PBMCs). Real-time PCR or real-time RT-PCR assays were used to measure viral DNA or Cap mRNA, respectively. The study demonstrated that PCV2 replication increased in infected PBMCs over time. Replication within infected PBMCs was significantly (P<0.05) increased when PBMCs were stimulated with ConA, compared to unstimulated PBMCs. The data showed a strong correlation between the level of PCV2 Cap mRNA and the level of viral DNA in the ConA stimulated PBMCs. Replication of PCV2 was also assessed in T lymphocyte- and monocyte/macrophage-enriched or monocyte/macrophage-depleted PBMC populations which had been stimulated with ConA for 3 days. It was demonstrated that the enriched T lymphocytes and the monocyte/macrophage-depleted PBMCs had significantly higher Cap mRNA and viral DNA levels (P<0.05) compared to the monocyte/macrophage-enriched population, indicating that in addition to monocytes/macrophages, PCV2 replicates in lymphocytes, particularly T lymphocytes following stimulation. These results suggest that the presence of activated T lymphocytes may play an important role in PCV2 replication and potentially the development of clinical disease.

Will bluetongue come on the wind to the United Kingdom in 2007?

In 2006, over 2000 cases of bluetongue were recorded in northern Europe. The disease, which has been more typically associated with Mediterranean areas, is believed to have become established hundreds of kilometres to the north of its traditional area, probably as a consequence of the hottest summer/autumn period since records began. In this special article, John Gloster and colleagues describe the meteorological conditions surrounding the 2006 outbreak, and investigate the possibility of bluetongue virus (BTV) spreading on the wind to the UK in 2007. For this to happen there would need to be a source of windborne virus, together with a susceptible population of ruminants in the vicinity of the coast. Evidence from outbreaks in the Mediterranean Basin suggests that long-distance transport of BTV-infected vectors has already occurred, at least in that region. The overall likelihood of this occurring in northern Europe depends critically on whether the virus overwinters on the near continent; this will not be known until around May 2007. The 2006 outbreak has highlighted the importance of understanding the impact of climate change on animal disease.

Spatial and temporal distribution of bluetongue and its Culicoides vectors in Bulgaria

Surveillance of Culicoides (Diptera: Ceratopogonidae) biting midges was carried out between 2001 and 2003, at 119 sites within a 50 x 50-km grid distributed across Bulgaria, using light trap collections around the time of peak adult midge abundance. Sentinel and ad hoc serum surveillance of hosts susceptible to bluetongue infection was carried out at around 300 sites between 1999 and 2003. Following the initial incursion of bluetongue virus 9 (BTV-9) into Bourgas province in 1999, affecting 85 villages along the southern border, a further 76 villages were affected along the western border in 2001, with outbreaks extending as far north as 43.6 degrees N. The BTV-9 strain in circulation was found to have a low pathogenicity for Bulgarian sheep populations, with less than 2% of susceptible individuals becoming sick and seroconversions detected up to 30 km from recorded outbreaks in the south. The major Old World vector Culicoides imicola Kieffer was not detected among over 70,000 Culicoides identified in summer collections, suggesting that BTV-9 transmission in Bulgaria was primarily carried out by indigenous European vectors. The most likely candidates, the Palaearctic species complexes - the Culicoides obsoletus Meigen and C. pulicaris L. complexes - were widespread and abundant across the whole country. The C. obsoletus complex represented 75% of all individuals trapped in summer and occurred in high catch sizes (up to 15,000 individuals per night) but was not found across all outbreak sites, indicating that both Palearctic complexes probably played a role in transmission. Within the C. pulicaris complex, only C. pulicaris s.s., C. punctatus Meigen and C. newsteadi Austen were sufficiently abundant and prevalent to have been widely involved in transmission, whilst within the C. obsoletus complex most trapped males were C. obsoletus s.s. Adult vectors were found to be largely absent from sites in west Bulgaria for a period of at least 3 months over winter, which, taken along with the spatiotemporal pattern of outbreaks in the region between years, indicates the virus may be overwintering here by an alternative mechanism - either by covert persistence in the vertebrate host or possibly by persistence in larval stages of the vector.

SANDO: Two novel mutations in POLG1 gene

Sensory ataxia with neuropathy, dysarthria and ophthalmoparesis represent the clinical triad of SANDO, a specific mitochondrial phenotype first reported in 1997 in association with multiple mitochondrial DNA deletions and mutations in POLG1 or more rarely in the C10orf2 (twinkle-helicase) gene. We report a 44-year-old man with SANDO who harboured two novel mutations (P648R/R807C) in the POLG1 gene.

Synthesis of hydroxy and methoxy perylene quinones, their spectroscopic and computational characterization, and their antiviral activity

Hydroxy and methoxy perylene quinones are synthesized in an attempt to isolate the essential spectroscopic and biological features of light-induced antiviral agents such as hypericin and hypocrellin. Unlike their naturally occurring counterparts, these synthetic quinones bear the carbonyl, hydroxyl, and methoxy groups in the "bay region." The hydroxy and methoxy compounds have rich absorption spectra with broad features in the visible (approximately 450-800 nm) and relatively more intense and narrow features at wavelengths < or = 350 nm. High-level ab initio quantum mechanical calculations assign the features in the absorption spectra to electronic transitions from S0 to S2 and to higher-lying electronic states. The calculations indicate that in the ground state the trans dihydroxy isomer is 12.5 kcal/mol lower in energy than the cis dihydroxy isomer and is thus the only species present. The lowest-energy trans methoxy ground state isomer and the lowest-energy cis methoxy ground state isomer are found to be degenerate. An additional cis methoxy isomer 6.3 kcal/mol higher in energy than the global minimum is assumed to contribute to the spectrum and is also considered. Finally, the synthetic compounds exhibit similar light-induced antiviral activity to each other, but significantly less than that of hypericin.

An alternative method of blood-feeding Culicoides imicola and other haematophagous Culicoides species for vector competence studies

The use of cotton wool pads saturated with blood/virus mixture for oral infection attempts was compared to membrane feeding for the assessment of vector competence in C. imicola Kieffer and C. bolitinos Meiswinkel (Diptera, Ceratopogonidae). Although lower infection rates were obtained using pad feeding, it was possible to clearly distinguish the levels of competence between species as well as differences in virus infection rates for various serotypes of bluetongue virus. Reduced infection rates with cotton pad feeding was partly due to a smaller volume of blood meals taken up. However, the method described is likely to be useful in situations where membrane feeding is not viable to separate populations with significant differences in vector competence.

Mathematical simulation of the diel O, S, and C biogeochemistry of a hypersaline microbial mat

The creation of a mathematical simulation model of photosynthetic microbial mats is important to our understanding of key biogeochemical cycles that may have altered the atmospheres and lithospheres of early Earth. A model is presented here as a tool to integrate empirical results from research on hypersaline mats from Baja California Sur (BCS), Mexico into a computational system that can be used to simulate biospheric inputs of trace gases to the atmosphere. The first version of our model, presented here, calculates fluxes and cycling of O(2), sulfide, and dissolved inorganic carbon (DIC) via abiotic components and via four major microbial guilds: cyanobacteria (CYA), sulfate reducing bacteria (SRB), purple sulfur bacteria (PSB) and colorless sulfur bacteria (CSB). We used generalized Monod-type equations that incorporate substrate and energy limits upon maximum rates of metabolic processes such as photosynthesis and sulfate reduction. We ran a simulation using temperature and irradiance inputs from data collected from a microbial mat in Guerrero Negro in BCS (Mexico). Model O(2), sulfide, and DIC concentration profiles and fluxes compared well with data collected in the field mats. There were some model-predicted features of biogeochemical cycling not observed in our actual measurements. For instance, large influxes and effluxes of DIC across the MBGC mat boundary may reveal previously unrecognized, but real, in situ limits on rates of biogeochemical processes. Some of the short-term variation in field-collected mat O(2) was not predicted by MBGC. This suggests a need both for more model sensitivity to small environmental fluctuations for the incorporation of a photorespiration function into the model.

Clotiapine for acute psychotic illnesses

BACKGROUND

Acute psychotic illnesses, especially when associated with agitated or violent behaviour, require urgent pharmacological tranquillisation or sedation. Clotiapine, a dibenzothiazepine neuroleptic, is being used for this purpose in several countries.

OBJECTIVES

To estimate the effects of clotiapine when compared to other 'standard' or 'non-standard' treatments for acute psychotic illnesses in controlling disturbed behaviour and reducing psychotic symptoms.

SEARCH STRATEGY

We updated previous searches by searching the Cochrane Schizophrenia Group Register (April 2004)

SELECTION CRITERIA

The review included randomised clinical trials comparing clotiapine with any other treatment for people with acute psychotic illnesses.

DATA COLLECTION AND ANALYSIS

Relevant studies were selected for inclusion, their quality was assessed and data extracted. Data were excluded where more than 50% of participants in any group were lost to follow up. For binary outcomes we calculated a standard estimation of the risk ratio (RR) and its 95% confidence interval (CI). For continuous outcomes, endpoint data were preferred to change data. Non-skewed data from valid scales were summated using a weighted mean difference (WMD).

MAIN RESULTS

We identified five relevant trials. None compared clotiapine with placebo, but control drugs were either antipsychotics (chlorpromazine, perphenazine, trifluoperazine and zuclopenthixol acetate) or benzodiazepines (lorazepam). Versus the antipsychotics, the results for 'no important global improvement' did not suggest clotiapine to be superior, or inferior, to chlorpromazine, perphenazine, or trifluoperazine (n = 83, 3 RCTs, RR 0.82 CI 0.22 to 3.05, I-squared 58%). Use of clotiapine when compared with chlorpromazine did change the proportion of people ready for hospital discharge by the end of the study (n = 49, 1 RCT, RR 1.04 95%CI 0.96 to 2.12). Overall, attrition rates were low. No significant difference was found for those allocated to clotiapine compared with people randomised to other antipsychotics (n = 121, RR 2.26 95%CI 0.40 to 13). Weak data suggests that clotiapine may result in less need for antiparkinsonian treatment compared with zuclopenthixol acetate (n = 38, RR 0.43 95%CI 0.02 to 0.98). Compared with lorazepam, clotiapine, when used to control aggressive/violent outbursts for people already treated with haloperidol, did not significantly improve mental state (WMD -3.36 95%CI -8.09 to 1.37). We could not pool much data due to skew or inadequate presentation of results. Economic outcomes and satisfaction with care were not addressed.

REVIEWERS' CONCLUSIONS

We found no evidence to support the use of clotiapine in preference to other 'standard' or 'non-standard' treatments for management of people with acute psychotic illness. All trials in this review have important methodological problems. We do not wish to discourage clinicians from using clotiapine in the psychiatric emergency, but well-designed, conducted and reported trials are needed to properly determine the efficacy of this drug.

Droperidol for acute psychosis

BACKGROUND

People suffering from acute psychotic illnesses, especially those associated with agitated or violent behaviour, may require urgent pharmacological tranquillisation or sedation. Droperidol, a butyrophenone neuroleptic, has been used for this purpose in several countries.

OBJECTIVES

To estimate the effects of droperidol compared to other treatments for controlling disturbed behaviour and reducing psychotic symptoms for people with suspected acute psychotic illnesses.

SEARCH STRATEGY

We updated previous searches by searching the Cochrane Schizophrenia Group Register (September 2003). References of all identified studies were searched for further trial citations and authors of trials were contacted. Twenty-one other databases were also searched as part of a broader project and this composite database was searched for this review. This was supplemented by hand searching reference lists and contacting both the pharmacological industry and relevant authors.

SELECTION CRITERIA

The review included randomised controlled trials comparing droperidol to any other treatment for people with suspected acute psychotic illnesses, including schizophrenia, schizoaffective disorder, mixed affective disorders, the manic phase of bipolar disorder or a brief psychotic episode.

DATA COLLECTION AND ANALYSIS

Relevant studies were selected for inclusion, their quality was assessed and data extracted. Data were excluded when more than 50% of participants were lost to follow up. For binary outcomes, standard estimates of risk ratio (RR) and the corresponding 95% confidence intervals (CI) were calculated. Where possible, weighted number needed to treat or harm statistics (NNT, NNH), and the corresponding 95% confidence intervals (CI), were calculated.

MAIN RESULTS

We identified only two relevant trials. One additional study focused on outcomes at 30 days rather than at a few hours. One small (n = 41) randomised trial compared intravenous (iv) droperidol (10 mg) with iv placebo and found that people allocated to droperidol were significantly less likely to need additional injections of another drug, haloperidol, in the first few minutes (n = 41, RR 0.37 CI 0.2 to 0.7, NNT 2 CI 1 to 10) compared to those given placebo. By 90 minutes this difference was still evident but not statistically significant (RR 0.46 CI 0.2 to 1.2). When 5 mg intramuscular (im) droperidol was compared with 5 mg im haloperidol, those given droperidol were also less likely to need additional injections by 30 minutes, than those given haloperidol, but this result was not statistically significant (n = 27, RR 0.45 CI 0.2 to 1.01). One person out of the 16 given haloperidol experienced a mild dystonic reaction (muscle spasms or abnormal contractions), while none of the 11 people allocated to droperidol were reported to have experienced adverse effects.

REVIEWERS' CONCLUSIONS

This is an important, and surprisingly under-researched, area. To date, use of droperidol for emergency situations has been justified by experience rather than evidence from well conducted and reported randomised trials, but, as world reserves diminish, droperidol will no longer be a treatment option.