Integrated control of ticks and tick-borne diseases

Integrated control of ticks and tick-borne diseases (ICTTD) is currently promoted by an international project, supported by the European Union, with the aim to increase livestock productivity through the development of improved strategies for tick control, vaccine delivery and integrated diagnostics for tickborne diseases. This paper gives a brief overview of the ICTTD project activities against the background of recent initiatives to assess the impact of ticks and tick-borne diseases in the Mediterranean region.     

菊花病虫害综合防治研究

系统调查了菊花病毒病、霜霉病、叶斑病、叶面害虫,蚜虫天敌种类及其流行规律,研究了组培脱毒苗,地膜覆盖移栽,与高秆作物套作、摘顶稍、利用昆虫天敌及化学防治等综合治理效果,测定了农药残留量,结果表明,菊花组培苗脱毒率在60％左右,脱毒苗增产50％以上,叶枯病,霜霉病病叶率下降28％－30％,虫口密度下降40％,在收菊花前1个月使用拟菊酯杀虫剂,农药残留量低于允许值,不会对菊花和和环境造成污染。     

Appropriate models for the management of infectious diseases

BackgroundMathematical models have become invaluable management tools for epidemiologists, both shedding light on the mechanisms underlying observed dynamics as well as making quantitative predictions on the effectiveness of different control measures. Here, we explain how substantial biases are introduced by two important, yet largely ignored, assumptions at the core of the vast majority of such models.ConclusionThis work aims to highlight that, when developing models for public health use, we need to pay careful attention to the intrinsic assumptions embedded within classical frameworks.     

Larval development of Aedes aegypti and Aedes albopictus in peri-urban brackish water and its implications for transmission of arboviral diseases

Aedes aegypti (Linnaeus) and Aedes albopictus Skuse mosquitoes transmit serious human arboviral diseases including yellow fever, dengue and chikungunya in many tropical and sub-tropical countries. Females of the two species have adapted to undergo preimaginal development in natural or artificial collections of freshwater near human habitations and feed on human blood. While there is an effective vaccine against yellow fever, the control of dengue and chikungunya is mainly dependent on reducing freshwater preimaginal development habitats of the two vectors. We show here that Ae. aegypti and Ae. albopictus lay eggs and their larvae survive to emerge as adults in brackish water (water with <0.5 ppt or parts per thousand, 0.5-30 ppt and >30 ppt salt are termed fresh, brackish and saline respectively). Brackish water with salinity of 2 to 15 ppt in discarded plastic and glass containers, abandoned fishing boats and unused wells in coastal peri-urban environment were found to contain Ae. aegypti and Ae. albopictus larvae. Relatively high incidence of dengue in Jaffna city, Sri Lanka was observed in the vicinity of brackish water habitats containing Ae. aegypti larvae. These observations raise the possibility that brackish water-adapted Ae. aegypti and Ae. albopictus may play a hitherto unrecognized role in transmitting dengue, chikungunya and yellow fever in coastal urban areas. National and international health authorities therefore need to take the findings into consideration and extend their vector control efforts, which are presently focused on urban freshwater habitats, to include brackish water larval development habitats.     

Lessons of Aedes aegypti control in Thailand

Abstract. The incidence of dengue haemorrhagic fever (DHF) in Thailand has increased cyclically since the first recognized outbreak in 1958. Without an effective vaccine against dengue, and considering the clinical difficulty of treating DHF cases, vector control is needed to prevent dengue transmission. Since the establishment of the WHO Aedes Research Unit in 1964, continued since 1973 as the WHO Collaborating Centre at the Department of Medical Research in Bangkok, much operational research has been carried out in Thailand on the bionomics and control of dengue vectors: Aedes aegypti and Ae.albopictus. This review shows that, as in most other countries, dengue vector control programmes in Thailand make little use of the procedures arising from research, nor have they reduced the upward trend of dengue or prevented DHF outbreaks. Implications of the reluctance to use results of operational research on vector control are considered and remedial suggestions made.     

Engineered exosomes: A new promise for the management of musculoskeletal diseases

Background

Exosomes are nanovesicles actively secreted by potentially all cell types, including tumour cells, with the primary role of extracellular systemic communication mediators, both at autocrine and paracrine levels, at short and long distances. Recently, different studies have used exosomes as a delivery system for a plethora of different molecules, such as drugs, microRNAs and proteins. This has been made possible thanks to the simplicity in exosomes engineering, their great stability and versatility for applications in oncology as well as in regenerative medicine.

Continuous health monitoring: integrating biomarkers for the management of chronic diseases

With the recent progresses of the information and communication technologies, biosensors and nanotechnologies, the access to continuing health monitoring is becoming real. The development of efficient, accurate and interactive solutions integrating biomarkers for continuing health monitoring might contribute to an improved care of some chronic diseases like hypertension, diabetes or heart failure. Continuing health monitoring might also enhance the efficiency and safety of patient’s treatments.     

Female-specific flightless (fsRIDL) phenotype for control of Aedes albopictus

Background

Aedes albopictus, the Asian tiger mosquito, is a vector of several arboviruses including dengue and chikungunya, and is also a significant nuisance mosquito. It is one of the most invasive of mosquitoes with a relentlessly increasing geographic distribution. Conventional control methods have so far failed to control Ae. albopictus adequately. Novel genetics-based strategies offer a promising alternative or aid towards efficient control of this mosquito.

Methodology/Principal Findings

We describe here the isolation, characterisation and use of the Ae. albopictus Actin-4 gene to drive a dominant lethal gene in the indirect flight muscles of Ae. albopictus, thus inducing a conditional female-specific late-acting flightless phenotype. We also show that in this context, the Actin-4 regulatory regions from both Ae. albopictus and Ae. aegypti can be used to provide conditional female-specific flightlessness in either species.

Conclusion/Significance

With the disease-transmitting females incapacitated, the female flightless phenotype encompasses a genetic sexing mechanism and would be suitable for controlling Ae. albopictus using a male-only release approach as part of an integrated pest management strategy.     

Drugs for the control of parasitic diseases: current status and development

The control of parasitic disease requires a complex interplay of activities in the fields of public health, education, political will and medical science. For every parasitic disease, the nature of the interplay is different because the essential factors vary greatly, including: (i) the presence or absence of a vector or animal reservoir; (ii) whether the available drugs are effective, acceptable or affordable to the patient; and (iii) whether the politico-economic climate supports or retards public health measures. But, throughout the whole spectrum of parasitic infections of humans, there is a need for treatment, and the search for better drugs is a perpetual process. Advances in science, especially in the field of parasite genomics and its attendant technology, have opened up possibilities for new drugs which were unimagined just a few years ago. By contrast, the escalating costs of drug discovery programmes make research and development particularly difficult to promote and sustain in today's global economy. Of the 1223 new drugs brought to the market between 1975 and 1996, 1% (11 new compounds and two reformulations) were treatments for tropical diseases [1]. This special issue of Trends in Parasitology and the accompanying poster examine some of the developments in this fascinating field.     

Biochemical and cytoimmunological evidence for the control of Aedes aegypti larval trypsin with Aea-TMOF

Trypsin and chymotrypsin-like enzymes were detected in the gut of Aedes aegypti in the four larval instar and pupal developmental stages. Although overall the amount of trypsin synthesized in the larval gut was 2-fold higher than chymotrypsin, both enzymes are important in food digestion. Feeding Aea-Trypsin Modulating Oostatic Factor (TMOF) to Ae. aegypti and Culex quinquefasciatus larvae inhibited trypsin biosynthesis in the larval gut, stunted larval growth and development, and caused mortality. Aea-TMOF induced mortality in Ae. aegypti, Cx. quinquefasciatus, Culex nigripalpus, Anopheles quadrimaculatus, and Aedes taeniorhynchus larvae, indicating that many mosquito species have a TMOF-like hormone. The differences in potency of TMOF on different mosquito species suggest that analogues in other species are similar but may differ in amino acid sequence or are transported differently through the gut. Feeding of 29 different Aea-TMOF analogues to mosquito larvae indicated that full biological activity of the hormone is achieved with the tetrapeptide YDPA. Using cytoimmunochemical analysis, intrinsic TMOF was localized to ganglia of the central nervous system in larvae and male and female Ae. aegypti adults. The subesophageal, thoracic, and abdominal ganglia of both larval and adult mosquitoes contained immunoreactive cells. Immunoreactive cells were absent in the corpus cardiacum of newly molted 4th instar larvae but were found in late 4th instar larvae. In both males and females, the intrinsic neurosecretory cells of the corpus cardiacum were filled with densely stained immunoreactive material. These results indicate that TMOF-immunoreactive material is synthesized in sugar-fed male and female adults and larvae by the central nervous system cells.