Right ventricular dysfunction in patients with COVID-19 pneumonitis whose lungs are mechanically ventilated: a multicentre prospective cohort study.

Cardiovascular complications due to COVID-19, such as right ventricular dysfunction, are common. The combination of acute respiratory distress syndrome, invasive mechanical ventilation, thromboembolic disease and direct myocardial injury creates conditions where right ventricular dysfunction is likely to occur. We undertook a prospective, multicentre cohort study in 10 Scottish intensive care units of patients with COVID-19 pneumonitis whose lungs were mechanically ventilated. Right ventricular dysfunction was defined as the presence of severe right ventricular dilation and interventricular septal flattening. To explore the role of myocardial injury, high-sensitivity troponin and N-terminal pro B-type natriuretic peptide plasma levels were measured in all patients. We recruited 121 patients and 118 (98%) underwent imaging. It was possible to determine the primary outcome in 112 (91%). Severe right ventricular dilation was present in 31 (28%), with interventricular septal flattening present in nine (8%). Right ventricular dysfunction (the combination of these two parameters) was present in seven (6%, 95%CI 3-13%). Thirty-day mortality was 86% in those with right ventricular dysfunction as compared with 45% in those without (p = 0.051). Patients with right ventricular dysfunction were more likely to have: pulmonary thromboembolism (p < 0.001); higher plateau airway pressure (p = 0.048); lower dynamic compliance (p = 0.031); higher plasma N-terminal pro B-type natriuretic peptide levels (p = 0.006); and raised plasma troponin levels (p = 0.048). Our results demonstrate a prevalence of right ventricular dysfunction of 6%, which was associated with increased mortality (86%). Associations were also observed between right ventricular dysfunction and aetiological domains of: acute respiratory distress syndrome; ventilation; thromboembolic disease; and direct myocardial injury, implying a complex multifactorial pathophysiology.

Association between anaesthetic technique and unplanned admission to intensive care after thoracic lung resection surgery: the second Association of Cardiothoracic Anaesthesia and Critical Care (ACTACC) National Audit.

Unplanned intensive care admission is a devastating complication of lung resection and is associated with significantly increased mortality. We carried out a two-year retrospective national multicentre cohort study to investigate the influence of anaesthetic and analgesic technique on the need for unplanned postoperative intensive care admission. All patients undergoing lung resection surgery in 16 thoracic surgical centres in the UK in the calendar years 2013 and 2014 were included. We defined critical care admission as the unplanned need for either tracheal intubation and mechanical ventilation or renal replacement therapy, and sought an association between mode of anaesthesia (total intravenous anaesthesia vs. volatile) and analgesic technique (epidural vs. paravertebral) and need for intensive care admission. A total of 253 out of 11,208 patients undergoing lung resection in the study period had an unplanned admission to intensive care in the postoperative period, giving an incidence of intensive care unit admission of 2.3% (95%CI 2.0-2.6%). Patients who had an unplanned admission to intensive care unit had a higher mortality (29.00% vs. 0.03%, p < 0.001), and hospital length of stay was increased (26 vs. 6 days, p < 0.001). Across univariate, complete case and multiple imputation (multivariate) models, there was a strong and significant effect of both anaesthetic and analgesic technique on the need for intensive care admission. Patients receiving total intravenous anaesthesia (OR 0.50 (95%CI 0.34-0.70)), and patients receiving epidural analgesia (OR 0.56 (95%CI 0.41-0.78)) were less likely to have an unplanned admission to intensive care after thoracic surgery. This large retrospective study suggests a significant effect of both anaesthetic and analgesic technique on outcome in patients undergoing lung resection. We must emphasise that the observed association does not directly imply causation, and suggest that well-conducted, large-scale randomised controlled trials are required to address these fundamental questions.

A novel video-tracking system to quantify the behaviour of nocturnal mosquitoes attacking human hosts in the field.

Many vectors of malaria and other infections spend most of their adult life within human homes, the environment where they bloodfeed and rest, and where control has been most successful. Yet, knowledge of peri-domestic mosquito behaviour is limited, particularly how mosquitoes find and attack human hosts or how insecticides impact on behaviour. This is partly because technology for tracking mosquitoes in their natural habitats, traditional dwellings in disease-endemic countries, has never been available. We describe a sensing device that enables observation and recording of nocturnal mosquitoes attacking humans with or without a bed net, in the laboratory and in rural Africa. The device addresses requirements for sub-millimetre resolution over a 2.0 × 1.2 × 2.0 m volume while using minimum irradiance. Data processing strategies to extract individual mosquito trajectories and algorithms to describe behaviour during host/net interactions are introduced. Results from UK laboratory and Tanzanian field tests showed that Culex quinquefasciatus activity was higher and focused on the bed net roof when a human host was present, in colonized and wild populations. Both C. quinquefasciatus and Anopheles gambiae exhibited similar behavioural modes, with average flight velocities varying by less than 10%. The system offers considerable potential for investigations in vector biology and many other fields.

Critical care after lung resection: CALoR 1, a single-centre pilot study.

Lung resection is associated with significant perioperative morbidity, and a proportion of patients will require intensive care following surgery. We set out to characterise this population, assess their burden of disease and investigate the influence of anaesthetic and surgical techniques on their admission rate. Over a two-year period, 1169 patients underwent surgery, with 30 patients (2.6%) requiring unplanned intensive care. Patients requiring support had a higher mortality (0.2% vs 26.7%, p < 0.001). Logistic regression (following adjustment for Thoracoscore) revealed that an open surgical approach was associated with higher likelihood of admission (p = 0.025, odds ratio = 5.25). There was also a trend towards increased likelihood of admission in patients who received volatile anaesthesia (p = 0.061, odds ratio = 2.08). This topic has been selected for further investigation as part of the 2015 Association of Cardiothoracic Anaesthetists (ACTA) second national collaborative audit, with this study providing pilot data before a multi-centre study.

Efficacy and community effectiveness of larvivorous fish for dengue vector control.

OBJECTIVE: To evaluate the efficacy and community effectiveness of larvivorous fish for the control of dengue vectors and dengue transmission, when used as a single agent or in combination with other vector control methods. METHOD: Comprehensive literature search of published and grey literature using PubMed, EMBASE (DMDI), Web of Science, WHOLIS, WILEY, LILACS, GIFT, Cochrane Library, ELDIS, New York Academy of Medicine Grey Literature Report and Google. All results were checked for duplicates and examined for eligibility. Methodological quality of the studies was assessed using RoBANS. RESULTS: Thirteen articles were considered eligible for inclusion. Incorporating a wide range of interventions and outcome measures, three were efficacy studies and 10 assessed community effectiveness. None of the studies were randomised or cluster-randomised controlled trials. All three efficacy studies and seven community effectiveness studies investigated fish as a single agent. All efficacy studies reported elimination of Aedes larvae from treated containers, while community effectiveness studies reported reductions in immature vector stages, two of which also detected a continuous decline over 2 years. An impact on adult mosquitoes was shown in only two community effectiveness studies. Reductions in dengue cases following intervention were reported in two studies, but it was not possible to attribute this to the intervention. CONCLUSION: While the use of larvivorous fish as a single agent or in combination with other control measures could lead to reductions in immature vector stages, considerable limitations in all the studies restricted any conclusions with respect to the evaluation of community effectiveness. Evidence for the community effectiveness of larvivorous fish as a single agent remains minimal and cluster-randomised controlled studies that include the assessment of impact on dengue are recommended.

Dengue disease surveillance: an updated systematic literature review.

OBJECTIVES: To review the evidence for the application of tools for dengue outbreak prediction/detection and trend monitoring in passive and active disease surveillance systems in order to develop recommendations for endemic countries and identify important research needs. METHODS: This systematic literature review followed the protocol of a review from 2008, extending the systematic search from January 2007 to February 2013 on PubMed, EMBASE, CDSR, WHOLIS and Lilacs. Data reporting followed the PRISMA statement. The eligibility criteria comprised (i) population at risk of dengue, (ii) dengue disease surveillance, (iii) outcome of surveillance described and (iv) empirical data evaluated. The analysis classified studies based on the purpose of the surveillance programme. The main limitation of the review was expected publication bias. RESULTS: A total of 1116 papers were identified of which 36 articles were included in the review. Four cohort-based prospective studies calculated expansion factors demonstrating remarkable levels of underreporting in the surveillance systems. Several studies demonstrated that enhancement methods such as laboratory support, sentinel-based reporting and staff motivation contributed to improvements in dengue reporting. Additional improvements for passive surveillance systems are possible by incorporating simple data forms/entry/electronic-based reporting; defining clear system objectives; performing data analysis at the lowest possible level (e.g. district); seeking regular data feedback. Six studies showed that serotype changes were positively correlated with the number of reported cases or with dengue incidence, with lag times of up to 6 months. Three studies found that data on internet searches and event-based surveillance correlated well with the epidemic curve derived from surveillance data. CONCLUSIONS: Passive surveillance providing the baseline for outbreak alert should be strengthened and appropriate threshold levels for outbreak alerts investigated. Additional enhancement tools such as syndromic surveillance, laboratory support and motivation strategies can be added. Appropriate alert signals need to be identified and integrated into a risk assessment tool. Shifts in dengue serotypes/genotype or electronic event-based surveillance have also considerable potential as indicator in dengue surveillance. Further research on evidence-based response strategies and cost-effectiveness is needed.

Assessing the relationship between vector indices and dengue transmission: a systematic review of the evidence.

BACKGROUND: Despite doubts about methods used and the association between vector density and dengue transmission, routine sampling of mosquito vector populations is common in dengue-endemic countries worldwide. This study examined the evidence from published studies for the existence of any quantitative relationship between vector indices and dengue cases. METHODOLOGY/PRINCIPAL FINDINGS: From a total of 1205 papers identified in database searches following Cochrane and PRISMA Group guidelines, 18 were included for review. Eligibility criteria included 3-month study duration and dengue case confirmation by WHO case definition and/or serology. A range of designs were seen, particularly in spatial sampling and analyses, and all but 3 were classed as weak study designs. Eleven of eighteen studies generated Stegomyia indices from combined larval and pupal data. Adult vector data were reported in only three studies. Of thirteen studies that investigated associations between vector indices and dengue cases, 4 reported positive correlations, 4 found no correlation and 5 reported ambiguous or inconclusive associations. Six out of 7 studies that measured Breteau Indices reported dengue transmission at levels below the currently accepted threshold of 5. CONCLUSIONS/SIGNIFICANCE: There was little evidence of quantifiable associations between vector indices and dengue transmission that could reliably be used for outbreak prediction. This review highlighted the need for standardized sampling protocols that adequately consider dengue spatial heterogeneity. Recommendations for more appropriately designed studies include: standardized study design to elucidate the relationship between vector abundance and dengue transmission; adult mosquito sampling should be routine; single values of Breteau or other indices are not reliable universal dengue transmission thresholds; better knowledge of vector ecology is required.

Multi-scale analysis of the associations among egg, larval and pupal surveys and the presence and abundance of adult female Aedes aegypti (Stegomyia aegypti) in the city of Merida, Mexico.

Despite decades of research, there is still no agreement on which indices of Aedes aegypti (Stegomyia aegypti) (Diptera: Culicidae) presence and abundance better quantify entomological risk for dengue. This study reports the results of a multi-scale, cross-sectional entomological survey carried out in 1160 households in the city of Merida, Mexico to establish: (a) the correlation between levels of Ae. aegypti presence and abundance detected with aspirators and ovitraps; (b) which immature and egg indices correlate with the presence and abundance of Ae. aegypti females, and (c) the correlations amongst traditional Aedes indices and their modifications for pupae at the household level and within medium-sized geographic areas used for vector surveillance. Our analyses show that ovitrap positivity was significantly associated with indoor adult Ae. aegypti presence [odds ratio (OR) = 1.50; P = 0.03], that the presence of pupae is associated with adult presence at the household level (OR = 2.27; P = 0.001), that classic Aedes indices are informative only when they account for pupae, and that window screens provide a significant level of protection against peridomestic Ae. aegypti (OR = 0.59; P = 0.02). Results reinforce the potential of using both positive collections in outdoor ovitraps and the presence of pupae as sensitive indicators of indoor adult female presence.

Evaluation of the effectiveness of insecticide treated materials for household level dengue vector control.

OBJECTIVE: To assess the operational effectiveness of long-lasting insecticide treated materials (ITMs), when used at household level, for the control of Aedes aegypti in moderately infested urban and suburban areas. METHODS: In an intervention study, ITMs consisting of curtains and water jar-covers (made from PermaNet) were distributed under routine field conditions in 10 clusters (5 urban and 5 suburban), with over 4000 houses, in Trujillo, Venezuela. Impact of the interventions were determined by comparing pre-and post-intervention measures of the Breteau index (BI, number of positive containers/100 houses) and pupae per person index (PPI), and by comparison with indices from untreated areas of the same municipalities. The effect of ITM coverage was modeled. RESULTS: At distribution, the proportion of households with ≥1 ITM curtain was 79.7% in urban and 75.2% in suburban clusters, but decreased to 32.3% and 39.0%, respectively, after 18 months. The corresponding figures for the proportion of jars using ITM covers were 34.0% and 50.8% at distribution and 17.0% and 21.0% after 18 months, respectively. Prior to intervention, the BI was 8.5 in urban clusters and 42.4 in suburban clusters, and the PPI was 0.2 and 0.9, respectively. In both urban and suburban clusters, the BI showed a sustained 55% decrease, while no discernable pattern was observed at the municipal level. After controlling for confounding factors, the percentage ITM curtain coverage, but not ITM jar-cover coverage, was significantly associated with both entomological indices (Incidence Rate Ratio = 0.98; 95%CI 0.97-0.99). The IRR implied that ITM curtain coverage of at least 50% was necessary to reduce A. aegypti infestation levels by 50%. CONCLUSION: Deployment of insecticide treated window curtains in households can result in significant reductions in A. aegypti levels when dengue vector infestations are moderate, but the magnitude of the effect depends on the coverage attained, which itself can decline rapidly over time.

Cohort trial reveals community impact of insecticide-treated nets on malariometric indices in urban Ghana.

The efficacy of insecticide-treated nets (ITNs) in prevention of malaria and anaemia has been shown in rural settings, but their impact in urban settings is unknown. We carried out an ITN intervention in two communities in urban Accra, Ghana, where local malaria transmission is known to occur. There was evidence for a mass or community effect, despite ITN use by fewer than 35% of households. Children living within 300 m of a household with an ITN had higher haemoglobin concentrations (0.5g/dl higher, P=0.011) and less anaemia (odds ratio 2.21, 95% CI 1.08-4.52, P=0.031 at month 6), than children living more than 300 m away from a household with an ITN, although malaria parasitaemias were similar. With urban populations growing rapidly across Africa, this study shows that ITNs will be an effective tool to assist African countries to achieve their Millennium Development Goals in urban settings. [Registered trial number ISRCTN42261314; http://www.controlled-trials.com/ISRCTN42261314].

The elimination of the onchocerciasis vector from the island of Bioko as a result of larviciding by the WHO African Programme for Onchocerciasis Control.

The island of Bioko is part of the Republic of Equatorial Guinea and is the only island in the World to have endemic onchocerciasis. The disease is hyperendemic and shows a forest-type epidemiology with low levels of blindness and high levels of skin disease, and the whole population of 68,000 is estimated to be at risk. Control of onchocerciasis began in 1990 using ivermectin and this yielded significant clinical benefits but transmission was not interrupted. Feasibility and preparatory studies carried out between 1995 and 2002 confirmed the probable isolation of the vector on the island, the high vectorial efficiency of the Bioko form of Simulium yahense, the seasonality of river flow, blackfly breeding and biting densities, and the distribution of the vector breeding sites. It was proposed that larviciding should be carried out from January to April, when most of the island's rivers were dry or too low to support Simulium damnosum s.l., and that most rivers would not need to be treated above 500 m altitude because they were too small to support the breeding of S. damnosum s.l. Larviciding (with temephos) would need to be carried out by helicopter (because of problems of access by land), supplemented by ground-based delivery. Insecticide susceptibility trials showed that the Bioko form was highly susceptible to temephos, and insecticide carry was tested in the rivers by assessing the length of river in which S. damnosum s.l. larvae were killed below a temephos dosing point. Regular fly catching points were established in 1999 to provide pre-control biting densities, and to act as monitoring points for control efforts. An environmental impact assessment concluded that the proposed control programme could be expected to do little damage, and a large-scale larviciding trial using ground-based applications of temephos (Abate 20EC) throughout the northern (accessible) part of the island was carried out for five weeks from 12 February 2001. Following this, a first attempt to eliminate the vectors was conducted using helicopter and ground-based applications of temephos from February to May 2003, but this was not successful because some vector populations persisted and subsequently spread throughout the island. A second attempt from January to May 2005 aimed to treat all flowing watercourses and greatly increased the number of treatment points. This led to the successful elimination of the vector. The last biting S. damnosum s.l. was caught in March 2005 and none have been found since then for more than 3 years.

Community knowledge, attitudes and practices related to tick-borne relapsing fever in dodoma rural district, central Tanzania.

Tick-borne Relapsing Fever (TBRF) is a vector-borne disease of humans which causes serious illness, primarily for children under five years old and pregnant women. Understanding people's knowledge, attitude and practices on the disease is important in designing appropriate interventions. This study was conducted to explore community knowledge, attitudes and practices regarding TBRF transmission and control to provide baseline data for the planned scaling up of intervention in Dodoma rural District in central Tanzania. A total of 198 heads of households were interviewed using a semi-structured questionnaire. Of these, 94.5% were aware of TBRF. Fever of unknown origin (69.5%), body pain (8.5%), headache (8.5%), chills (4.5%) and vomiting (3.5%) were the most commonly mentioned symptoms. The domestic tick-infestation and tick-bites was known to 82.8%. High domestic tick infestation reported to occur during dry season (85.4%). The majority believed that the disease spreads through tick-bites (85.9%). Regular plastering of house floors and walls was the most common method used by the community to control domestic tick infestation (96.5 %). Majority (84.3%) of the respondents preferred public healthcare facilities for treatment. Only a small proportion (15.7%) preferred using traditional medicines. Poor knowledge of the study subjects about the disease and its control underscores the need for health educational campaigns if any control and/or elimination programme is to succeed.

Development and application of a simple colorimetric assay reveals widespread distribution of sodium channel mutations in Thai populations of Aedes aegypti.

Dengue fever and its more serious complications dengue haemorrhagic fever and dengue shock syndrome are growing public health problems in tropical and subtropical countries. In the absence of a vaccine, most dengue control programmes rely heavily on the use of insecticides to target the Aedes mosquito vectors. As a limited number of insecticides are routinely used in control, monitoring for the presence of resistance is an essential component of dengue prevention programmes. The pyrethroid insecticides target the voltage-gated sodium channel on the insects' neurons. Substitutions at residue 1016 of this protein have been associated with pyrethroid and DDT resistance in Aedes aegypti populations from Latin America and Asia. Here we report on the development of a simple colorimetric assay to detect these mutations in individual mosquitoes. Evaluation of this diagnostic assay on 180 Ae. aegypti individuals from Thailand revealed the presence of high frequencies of the Val1016Gly mutation throughout the country. The assay requires no specialised equipment and will enable monitoring for insecticide resistance associated alleles to be routinely incorporated into dengue surveillance operations.

Insecticide-treated bednets to control dengue vectors: preliminary evidence from a controlled trial in Haiti.

OBJECTIVES: Insecticide-treated bednets (ITNs) are effective in preventing nocturnally transmitted vector-borne diseases, but their effect on diurnally active dengue vectors has never been studied. We investigated the efficacy of ITNs in reducing Aedes aegypti populations and dengue transmission. METHODS: A cluster-randomized trial was carried out in Leogane, Haiti between July 2003 and July 2004. The study area (1017 houses) was divided into 18 sectors (clusters): nine received ITNs (Olyset(R) long-lasting insecticidal bednets) and nine were untreated controls. Entomological surveys [measuring Breteau (BI), house (HI), container (CI) and pupae per person (PPI) indices and oviposition activity] were undertaken at baseline and at 1 and 5 months post-intervention. All houses were georeferenced to enable spatial analysis. Control sectors received ITNs at 6 months, and a final entomological and attitudinal survey was undertaken at 12 months after baseline. Anti-dengue IgM seropositivity rates were measured at baseline and after 12 months. Efficacy of ITNs was assessed by WHO cone bioassays. RESULTS: At 1-month post-intervention, entomological indices fell in all sectors, with HI and BI in the bednet sectors reduced by 6.7 (95% CI -10.6, -2.7; P < 0.01) and 8.4 (95% CI -14.1, -2.6; P < 0.01) respectively. Moreover at 1 month, ovitraps in control sectors were significantly more likely to be positive than in bednet sectors (P < 0.01). By 5 months, all indices remained low and HI, CI and BI were also significantly lower than that of baseline in the control arm. Curiously, at 5 months, HI, CI and BI were lower in the control arm than that in the bednet arm. A final survey, 12 months after the initial baseline study (5 months after bednets had been given to all households) indicated that all indices were significantly lower than that at baseline (P < 0.001). Control houses located within 50 m of a bednet house had significantly lower CI (Z = -2.67, P = 0.008) and PPI (Z = -2.19, P = 0.028) at 1 month, an effect that extended to 100 m by 5 months (Z = -2.03, P = 0.042 and Z = -2.37, P = 0.018 respectively), suggesting a spill-over effect of the bednets. An IgM serosurvey showed a 15.3% decrease (95% CI 5.0-25.5%, P < 0.01) in the number of IgM-positive individuals from baseline to12 months later. CONCLUSIONS: Insecticide-treated bednets had an immediate effect on dengue vector populations after their introduction, and over the next 5-12 months, the presence of ITNs may have continued to affect vector populations and dengue transmission.

A mutation in the voltage-gated sodium channel gene associated with pyrethroid resistance in Latin American Aedes aegypti.

Pyrethroids are commonly used as mosquito adulticides and evolution of resistance to these compounds is a major threat to public health. 'Knockdown resistance' to pyrethroids (kdr) is frequently caused by nonsynonymous mutations in the voltage-gated sodium channel transmembrane protein (para) that reduce pyrethroid binding. Early detection of kdr is critical to the development of resistance management strategies in mosquitoes including Aedes aegypti, the most prevalent vector of dengue and yellow fever viruses. Brengues et al. described seven novel mutations in hydrophobic segment 6 of domain II of para in Ae. aegypti. Assays on larvae from strains bearing these mutations indicated reduced nerve sensitivity to permethrin inhibition. Two of these occurred in codons Iso1011 and Val1016 in exons 20 and 21 respectively. A transition in the third position of Iso1011 encoded a Met1011 replacement and a transversion in the second position of Val1016 encoded a Gly1016 replacement. We have screened this same region in 1318 mosquitoes in 32 additional strains; 30 from throughout Latin America. While the Gly1016 allele was never detected in Latin America, we found two new mutations in these same codons. A transition in the first position of codon 1011 encodes a Val replacement while a transition in the first position of codon 1016 encodes an Iso replacement. We developed PCR assays for these four mutations that can be read either on an agarose gel or as a melting curve. Selection experiments, one with deltamethrin on a field strain from Santiago de Cuba and another with permethrin on a strain from Isla Mujeres, Mexico rapidly increased the frequency of the Iso1016 allele. Bioassays of F(3) offspring arising from permethrin susceptible Val1016 homozygous parents and permethrin resistant Iso1016 homozygous parents show that Iso1016 segregates as a recessive allele in conferring kdr. Analysis of segregation between alleles at the 1011 and 1016 codons in the F(3) showed a high rate of recombination even though the two codons are only separated by a ~250 bp intron. The tools and information presented provide a means for early detection and characterization of kdr that is critical to the development of strategies for resistance management.

Does tick-borne relapsing fever have an animal reservoir in East Africa?

Tick-borne relapsing fevers (TBRF) are caused by infection with Borrelia spirochetes and transmitted to humans by ticks. All except East African TBRF, caused by Borrelia duttonii, are known zoonoses. This widespread, endemic and pathogenic infection has only been found in humans and the Ornithodoros sp. soft tick vectors. We investigated the role of domestic animals as possible reservoirs of infection in a TBRF endemic region. Tick infestations in households and pigpens were investigated in the villages near Mvumi hospital in central Tanzania. Blood from chickens and pigs was examined by PCR and flagellin gene sequencing was performed on any Borrelia sp. infections detected. A mark-recapture experiment investigated tick movement between pigpens and houses. The acceptability of chickens as tick hosts was also investigated. Tick infestation of the 122 houses investigated was high (47%). Pigpens also were tick infested (16%) and were more likely to be so if they were located close to tick infested households (p<0.001). PCR screening of peripheral blood found Borrelia infections in both chickens and pigs (11% and 8.9% respectively). Sequencing of a subset of positive samples revealed that the amplified Borrelia sp. flagellin gene fragments shared greatest homology with B. duttonii. In a mark-recapture experiment, ticks released in pigpens were recaptured inside human bedrooms. When offered chickens as hosts, over 20% of ticks fed. For the first time in East Africa, we record natural infections of Borrelia in domestic animals and show that tick populations may act as bridging vectors between animals and humans. These results, from villages where B. duttonii is already known to be prevalent and a major cause of illness in humans, and where it has been found at high levels in ticks, strongly support the case that it is a zoonosis. This increases understanding of the epidemiology and control of this important but neglected human disease.

Delivery of insecticide-treated net services through employer and community-based approaches in Kenya.

BACKGROUND AND OBJECTIVES: Many approaches have been used to deliver insecticide-treated nets (ITNs) to African communities in different settings. Between 1992 and 2002, the African Medical and Research Foundation (AMREF), Kenya, used two ITN delivery models: the employer-based approach and the community-based approach. These two approaches have never been compared in order to inform their potential for future ITN delivery. We aimed to (1) compare the extent of ITN ownership, use and retreatment coverage in different population groups in the employer and community-based models and (2) identify options for improving people's acceptance and use of treatment/retreatment services. METHODS: Qualitative and quantitative methods for data collection and analysis. A total of 2095 household heads were interviewed in the quantitative study, while purposively selected groups and key informants participated in the qualitative study. RESULTS: Net coverage (both treated and untreated nets) and retreatment rates with insecticides were significantly higher at employer-based sites (54.3%) than at community-based sites (35.0%). Bed net ownership has increased significantly since the start of AMREF interventions in 1998 in employer-based sites (from 27% to 61.1%); in community-based sites, it has either decreased (urban area, from 29.0% to 16.5%) or increased (rural area, from 17.0% to 49.1%). Retreatment rates in all sites were negatively influenced by the lack of information, cash and availability of insecticides. Satisfaction with the form of payment and services delivered was higher in employer-based sites. This was attributed to employers providing credit for the purchase of nets and retreatment kits and the employers' medical teams giving information on malaria and making follow-up visits on workers who fell ill. CONCLUSIONS: Employer-based delivery of ITNs was more successful than community-based delivery in attaining both high coverage with ITNs and higher rates of net retreatment. Methods used for the retreatment of nets, forms of payment and communication strategies should be convenient to communities. Organized community groups may continue to play an important role in remote rural areas.