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Background: West Nile virus (WNV) is a mosquito-borne virus that causes a febrile disease and may cause a fatal neurological illness in humans. We aimed to investigate the geographic distribution of Culicinae mosquitoes and their possible infection with WNV in Hormozgan Province, southern Iran. Methods: Field studies were carried out from June 2017 to May 2019. Different mosquito sampling methods were used monthly to collect mosquitoes from 22 sites. The Real-Time PCR technique was used to detect the virus infection in the mosquitoes. Results: Overall, 6165 mosquitoes were caught. The species were Culex theileri (33.25%), Cx. pipiens (20.45%), Cx. quinquefasciatus (10.51%), Aedes caspius (6.33%), Cx. tritaeniorhynchus (5.82%), Ae. vexans (4.10%), Cx. sinaiticus (3.62%), Cx. antennatus (3.29%), Culiseta longiareolata (2.81%), Cx. perexiguus (2.03%), Cs. subochrea (1.95%), Cx. mimeticus (1.49%), Cx. pusillus (1.38%), Cx. univittatus (1.27%), Cx. modestus (1.14%), and Cx. sitiens (0.57%). The molecular detection of virus infection in mosquitoes found to be negative for WNV. Conclusion: The presence of many species of mosquito vectors and high population traffic increase the risk of disease transmission is very high. Therefore, the way to restrict WNV infection factors is increasing the knowledge for personal protection measures to prevent mosquito bites.

Malaria is the most important mosquito-borne disease, which is transmitted by Anopheles species. According to the recent report of World Health Organization, there were an estimated 229 million malaria cases in 2019 in 87 malaria endemic countries. There are several vector control method specially using pesticides. The aim of this study was to collect all the data about insecticide resistant of malaria vectors in the Eastern Mediterranean region countries. In this study, all the published papers related to insecticide resistance of malaria vectors in the region were collected and resistant status of vectors in the countries was mapped. Resistance to different insecticide classes such as pyrethroids, organophosphate, organochlorine and carbamates were evaluated using World Health Organization guidelines. Results showed a wide variety of susceptibility/resistance status to these chemicals according to the location, historical context of pesticide used, genetic background of vectors, age and abdominal conditions of adults may play a role in the susceptibility status of these species to different insecticides. The results of this study is providing a guideline for countries to manage their vector control activities against insecticide resistance of malaria vectors and provide novel approaches such as male sterility, using Wolbachia, using new insecticide with new mode of action.

Blood feeding and resting behaviour of malaria vectors are the most influential factors in malaria transmission.To measure blood feeding and resting behaviour, conventional mosquito sampling methods were performed in an area with potential for malaria transmission.Adult mosquitoes were collected monthly from indoor/outdoor places by conventional sampling methods, and larval habitats were investigated. Enzyme-linked immunosorbent assay was used to measure the human blood index (HBI) of the mosquitoes.Anopheles stephensi, Anopheles culicifacies, Anopheles dthali and Anopheles fluviatilis, were collected. Overall, 1249 female Anopheles mosquitoes were captured on human and animal baits, but no human-vector contact occurred indoors. A. dthali, A. fluviatilis and A. culicifacies showed a greater tendency to outdoor resting places in contrast to A. stephensi, which had a propensity to indoor resting places. The seasonal biting activities of all species occurred at average temperatures between 23 and 27°C. HBI was measured as 27.2%, 20.7%, 19.1%, and 23.0% for A. fluviatilis, A. stephensi, A. culicifacies and A. dthali, respectively.Vector control strategy depends upon mosquito behaviour. Therefore, using appropriate sampling methods based on mosquito behaviour is critical for malaria control planning. Exophilic/exophagic habit of mosquito vectors leads to fewer human bites, resulting in biting protection. Exophilic behaviour also requires specific larvicidal operations in order to prevent and control malaria transmission.سلوك اللدغ والراحة لنواقل الملاريا في مقاطعة بندر عباس بجمهورية إيران الإسلامية.عبد الرسول مجاهدي، رضا سفاري، مسعود ياريان، عباس باكاري، أحمد رايسي، حميدة إدالات، موجغان بينيارديلان، عباس بودات، مرتضى زعيم، حميد رضا بصيري.يُعد سلوك الراحة وتغذية نواقل الملاريا على الدم أكثر العوامل تأثيراً في انتقال الملاريا.هدفت الدراسة إلى قياس سلوك الراحة والتغذية على الدم باستخدام طرق تقليدية لأخذ عينات البعوض في منطقة يحتمل فيها انتقال الملاريا.جرى جمع البعوض البالغ شهرياً من الأماكن المغلقة/ المفتوحة بطرق أخذ العينات التقليدية، كما جرى استقصاء موائل اليرقات. واستُخدمت مُقايسة المُمْتَزِّ المناعيّ المُرتبِط بالإِنزيم لقياس مؤشر الدم البشري للبعوض.جُعت الأنوفيلة الاصطفانية، والأنوفيلة البعوضية الوجه، وأنوفيلة دتالي، والأنوفيلة النهرية. وبصفة عامة، التُقط 1249 من أنثى بعوض الأنوفيلة على الطعوم البشرية والحيوانية، ولكن لم يحدث أي اتصال بين البشر والنواقل في الأماكن المغلقة. وأظهرت أنوفيلة دتالي والأنوفيلة النهرية والأنوفيلة البعوضية الوجه ميلاً أكبر إلى الخلود إلى الراحة في الأماكن المفتوحة على النقيض من الأنوفيلة الاصطفانية التي أظهرت ميلاً إلى الخلود إلى الراحة في الأماكن المغلقة. وتحدث أنشطة اللدغ الموسمية لجميع الأنواع في متوسط درجات حرارة تتراوح بين 23 و27 درجة مئوية. وتم قياس مؤشر الدم البشري عند 27.2٪ و20.7٪ و19.1٪ و23.0٪ للأنوفيلة النهرية والأنوفيلة الاصطفانية والأنوفيلة البعوضية الوجه وأنوفيلة دتالي على التوالي.تعتمد استراتيجية مكافحة النواقل على سلوك البعوض. ولذلك فإن اتباع طرق أخذ العينات المناسبة المستندة إلى سلوك البعوض أمر بالغ الأهمية في التخطيط لمكافحة الملاريا. ويؤدي ميل البعوض الناقل إلى التغذية والراحة في الأماكن المفتوحة إلى عدد أقل من اللدغات التي تصيب الإنسان، مما يؤدي إلى الحماية من اللدغ. كما يتطلب سلوك الراحة في الأماكن المفتوحة عمليات محددة لإبادة اليرقات من أجل الوقاية من انتقال الملاريا ومكافحته.Comportement de piqûre et de repos des vecteurs du paludisme dans le comté de Bandar-Abbas (République islamique d’Iran).L’alimentation en sang et le comportement de repos des vecteurs de paludisme sont les facteurs de transmission les plus importants de la maladie.Pour analyser les repas sanguins et le comportement de repos, on a utilisé des méthodes conventionnelles de collecte de moustiques dans une zone exposée au risque de transmission du paludisme.On a prélevé tous les mois des moustiques adultes à l’intérieur et à l’extérieur des habitations en recourant à des méthodes conventionnelles de collecte et des gîtes larvaires ont été étudiés. Un essai d’immuno-absorption enzymatique (ELISA) a été utilisé pour mesurer l’indice d'anthropophilie des moustiques.Les espèces suivantes d’anophèles ont été collectées : Anopheles stephensi, Anopheles culicifacies, Anopheles dthali et Anopheles fluviatilis. Au total, 1249 moustiques anophèles femelles ont été capturés à l’aide d’appâts humains et animaux, mais aucun contact homme-vecteur n’a été recensé à l’intérieur des habitations. A. dthali, A. fluviatilis et A. culicifacies avaient davantage tendance à choisir des lieux de repos extérieurs, contrairement à A. stephensi, qui avait tendance à se reposer à l’intérieur des habitations. Pour toutes les espèces, les activités de piqûres saisonnières ont eu lieu à des températures moyennes comprises entre 23 et 27 °C. L’indice d’anthropophilie a été évalué à 27,2 %, à 20,7 %, à 19,1 % et à 23,0 % pour A. fluviatilis, A. stephensi, A. culicifacies et A. dthali, respectivement.La stratégie de lutte antivectorielle dépend du comportement des moustiques. Par conséquent, il est essentiel d’utiliser des méthodes de collecte adaptées en fonction du comportement des moustiques pour la planification de la lutte antipaludique. L'exophilie et l’exophagie des vecteurs entraînent un nombre moins élevé de piqûres sur l’homme, ce qui se traduit par une protection contre les piqûres. Le comportement exophile nécessite également l’application de traitements larvicides particuliers pour prévenir la transmission du paludisme et lutter contre cette maladie.

Background While Iran is on the path to eliminating malaria, the disease with 4.9 million estimated cases and 9300 estimated deaths in 2018 remains a serious health problem in the World Health Organization (WHO) Eastern Mediterranean Region. Anopheles stephensi is the main malaria vector in Iran and its range extends from Iraq to western China. Recently, the vector invaded new territories in Sri Lanka and countries in the Horn of Africa. Insecticide resistance in An. stephensi is a potential issue in controlling the spread of this vector. Methods Data were collated from national and international databases, including PubMed, Google Scholar, Scopus, ScienceDirect, SID, and IranMedex using appropriate search terms. Results Indoor residual spaying (IRS) with DDT was piloted in Iran in 1945 and subsequently used in the malaria eradication programme. Resistance to DDT in An. stephensi was detected in Iran, Iraq, Pakistan, and Saudi Arabia in the late 1960s. Malathion was used for malaria control in Iran in 1967, then propoxur in 1978, followed by pirimiphos-methyl from 1992 to 1994. The pyrethroid insecticide lambda-cyhalothrin was used from 1994 to 2003 followed by deltamethrin IRS and long-lasting insecticidal nets (LLINs). Some of these insecticides with the same sequence were used in other malaria-endemic countries of the region. Pyrethroid resistance was detected in An. stephensi in Afghanistan in 2010, in 2011 in India and in 2012 in Iran. The newly invaded population of An. stephensi in Ethiopia was resistant to insecticides of all four major insecticide classes. Different mechanisms of insecticide resistance, including metabolic and insecticide target site insensitivity, have been developed in An. stephensi. Resistance to DDT was initially glutathione S-transferase based. Target site knockdown resistance was later selected by pyrethroids. Esterases and altered acetylcholinesterase are the underlying cause of organophosphate resistance and cytochrome p450s were involved in pyrethroid metabolic resistance. Conclusions Anopheles stephensi is a major malaria vector in Iran and many countries in the region and beyond. The species is leading in terms of development of insecticide resistance as well as developing a variety of resistance mechanisms. Knowledge of the evolution of insecticide resistance and their underlying mechanisms, in particular, are important to Iran, considering the final steps the country is taking towards malaria elimination, but also to other countries in the region for their battle against malaria. This systematic review may also be of value to countries and territories newly invaded by this species, especially in the Horn of Africa, where the malaria situation is already dire.

International trade of tires has been responsible for the introduction of invasive Aedes species into many countries. The present study aimed to determine the sources and volume of such trading in Iran and to establish and map points of entry for entomological surveillance.A list of tire importers, type and number of tires and source of their shipment was compiled, and the map of the main location(s) of their depot in the country was produced from 2017 to 2018. Contamination of imported tires with mosquito eggs or larvae was also determined. The samples from all parts of the warehouse were taken randomly from 4 to 20 tires every 15 days. In tires with a trace of water inside, the existence of the egg and larva of Aedes mosquitoes was investigated by sticking the glue band to the hot spot of left water inside the unpacked tires.Approximately one-third of the annual tire requirements of Iran were imported from 15 countries, most of which were endemic to Aedes aegypti and or Ae. albopictus. It is obligatory to import only wrapped tires. About 10% of total country consumption is imported through informal markets and smuggled. However, the unofficially imported tires are usually not wrapped. The majority of tire imports were made through the southern ports of the country. The main sites for depots of imported tires were located in four Iranian provinces, namely Tehran, Isfahan, Fars, and Sistan and Baluchestan. The latter is extremely important given its border with Pakistan. Depot locations were mostly unstructured, and tires were kept in the open air. All these depot locations were at the edge of towns and residential areas. Priority areas for routine entomological surveillance were established. Such as the previous studies, surveillance of imported tires for the presence of Aedes eggs or larvae was negative in this study.Mapping the entry points of imported tires and their origin is crucial to determine and prioritize sites for entomological surveillance of invasive mosquito species. Strengthening collaboration with customs authorities and the association of tire importers is imperative in this effort. The development of national rules and regulations for tire import is necessary to minimize the danger of the introduction of invasive vector species into the country.

In Iran, there are four pest domestic species of cockroaches: Periplaneta americana (Linnaeus, Blattodea: Blattidae), Blatta orientalis (Linnaeus, Blattodea: Blattidae), Blattella germanica (Linnaeus, Blattodea: Blattidae), and Supella longipalpa (Fabricius, Blattodea: Blattellidae). The aim of this study was to compile and review studies conducted on insecticide resistance of domestic cockroaches in Iran to assess the current knowledge and gaps. Twenty insecticides were used in susceptibility testing of cockroaches. The bioassay methods varied, and included surface contact (exposure tests), topical applications and feeding studies on baits. Resistance ratio (RR) stated in the reviewed studies showed that B. germanica was resistant (RR > 10) to DDT, permethrin, and cypermethrin, while P. americana and S. longipalpa were categorized as low levels of resistance (RR = 1-2). S. longipalpa is newly reported from houses in some areas of Iran, including Tehran, and there are very few studies on its' biology, ecology and insecticidal resistance. Most studies used adult cockroaches, while the susceptibility status of nymphs was evaluated only in few studies. Use of different test methods and lack of a World Health Organization (WHO) updated procedure, including revised/updated insecticide diagnostic dosages and test kits. The lack of susceptible strains of cockroaches was a major challenge in the assessment of data. A comprehensive national program for monitoring susceptibility of household pests to insecticides in Iran is of great concern and is highly recommended.

Background: West Nile Virus, a mosquito-borne flavivirus, causes a variety of symptoms in human, from asymptomatic infection to neuroinvasive disease. Several studies have been conducted on the seroprevalence of WNV infection in different areas from Iran. This study was performed to find the presence of antiviral antibodies in human serum among some high risk population and awareness of health care staff about symptom of the WNV infection. Methods: Study performed in five geographical districts based on high population of immigrant and domestic birds and prevalence of the antiviral antibodies in horses which was reported previously. Totally 150 human blood samples were collected during 2018. The samples collected from patients referred to the clinics. The ELISA method used to detect IgG and IgM antibody against WNV. Logistic regression models used to analyze the effect of sex, age, keeping birds and urban/rural residence on the risk of infection. The awareness of health care staff about symptom of infection surveyed. Results: From all blood donors, 41 samples (27.33%) showed positive to IgG antibody. From which 56.10% were males and remaining females. None of the mentioned factors had a significant relationship. Health care staff had less attention to the infection. Conclusions: Although the prevalence of antibodies was relatively high, due to the similarity to other viral diseases, health care staff had less attention to the disease. The study showed that people in these areas have been exposed to the virus. Further research activities are recommended for control of this arbovirus.

Background: Zika virus infection has recently attracted the attention of medical community. While clinical manifestations of the infection in adult cases are not severe and disease is not associated with high mortality rates, Zika virus infection can have an impact on fetal development and lead to severe neurodevelopmental abnormalities. Methods: To gain insight into different aspects of Zika virus infection, a comprehensive literature review was performed. With regard to epidemiology and geographical distribution of Zika virus infection, relevant information was extracted from CDC and WHO websites. Results: In this review, we discuss different basic and clinical aspects of Zika virus infection including virology, epidemiology and pathogenesis of disease. Laboratory methods required for the diagnosis of disease together with ethical issues associated with Zika virus infection will also be discussed in detail. Conclusion: Herein, we have tried to provide a multi-faceted view of Zika virus infection, with greater emphasis on disease status in Eastern Mediterranean Region.

Zika virus is transmitted by Aedes mosquitoes, especially, Ae. aegypti and Ae. albopictus. About 80% of the cases do not manifest any symptoms, and it is a self-limiting, mild viral infection. In 20% of the cases and only in fraction of those who do show the symptoms, important complications including Guillaine Barre'syndrome and microcephaly may occur. The emergence of Zika in 2016 in Brazil spreading to about 70 other countries prompted the WHO officials to declare the disease a Public Health Emergency with International Concern (PHEIC). This has led to increased concerns in health authorities of almost all countries making them embark on the strengthened human and vector surveillance, vector control and clinical management of the disease. Although the main vectors of the disease have not yet been able to establish in Iran, because of their occurrence in neighboring countries as well as increased global travel and trade, the country established a national advisory committee for capacity building, vector and human surveillance and case management of Aedes-borne diseases. This study aims at performing a literature review about global situation of Zika and Aedes mosquitoes, their distribution, biology and ecology from the past to present and the threat posed to Iran. Aedes aegypti was historically present in the checklist of Iranian mosquitoes and Ae. albopictus has recently been collected from Southern Iran, however, the species has apparently failed to establish in the country as comprehensive follow up entomological surveillance could not reproduce the findings. Although Zika was not detected in Iran, considering the expansion in tourism, travel and trade to and from Zika infected and Aedes infested countries, suitable climate and favorable prediction for establishment of Aedes vectors, Iran may well be at risk of invasion of Aedes vector species and the diseases they carry. Therefore, this review is of value particularly to health authorities in Iran and other WHO Eastern Mediterranean countries for sustained vigilance and preparedness for early detection and response, including vector control.

Background: Data on insecticide use for vector control are essential for guiding pesticide management systems on judicious and appropriate use, resistance management, and reduction of risks to human health and the environment. Objective: We studied the global use and trends of insecticide use for control of vector-borne diseases for the period 2000 through 2009. Methods: A survey was distributed to countries with vector control programs to request national data on vector control insecticide use, excluding the use of long-lasting insecticidal nets (LNs). Data were received from 125 countries, representing 97% of the human populations of 143 targeted countries. Results: The main disease targeted with insecticides was malaria, followed by dengue, leishmaniasis, and Chagas disease. The use of vector control insecticides was dominated by organochlorines [i.e., DDT (dichlorodiphenyltrichloroethane)] in terms of quantity applied (71% of total) and by pyrethroids in terms of the surface or area covered (81% of total). Global use of DDT for vector control, most of which was in India alone, was fairly constant during 2000 through 2009. In Africa, pyrethroid use increased in countries that also achieved high coverage for LNs, and DDT increased sharply until 2008 but dropped in 2009. Conclusions: The global use of DDT has not changed substantially since the Stockholm Convention went into effect. The dominance of pyrethroid use has major implications because of the spread of insecticide resistance with the potential to reduce the efficacy of LNs. Managing insecticide resistance should be coordinated between disease-specific programs and sectors of public health and agriculture within the context of an integrated vector management approach.

BACKGROUND: Legislation and regulation of pesticides used in public health are essential for reducing risks to human health and the environment. OBJECTIVE: We assessed the global situation on legislation and regulatory control of public health pesticides. METHODS: A peer-reviewed and field-tested questionnaire was distributed to 142 member states of the World Health Organization (WHO); 113 states completed the questionnaire. RESULTS: Legislation on public health pesticides was absent in 25% of the countries. Where present, legislation often lacked comprehensiveness, for example, on basic aspects such as labeling, storage, transport, and disposal of public health pesticides. Guidelines or essential requirements for the process of pesticide registration were lacking in many countries. The capacity to enforce regulations was considered to be weak across WHO regions. Half of all countries lacked pesticide quality control laboratories, and two-thirds reported high concern over quality of products on the market. National statistics on production and trade of pesticides and poisoning incidents were lacking in many countries. Despite the shortcomings, WHO recommendations were considered to constitute a supportive or sole basis in national registration. Also, some regions showed high participation of countries in regional schemes to harmonize pesticide registration requirements. CONCLUSIONS: Critical deficiencies are evident in the legislative and regulatory framework for public health pesticides across regions, posing risks to human health and the environment. Recent experience in some countries with situational analysis, needs assessment, action planning, and regional collaboration has signaled a promising way forward.

In this study, the activity of cyromazine was evaluated following WHO standard procedures against susceptible and resistant mosquito strains of Anopheles gambiae, Culex quinquefasciatus, and Aedes aegypti. The dose for 50% and 90% inhibition of adult emergence (IE50 and IE90) ranged from 0.028 mg/liter to 0.17 mg/liter and from 0.075 mg/liter to 0.42 mg/liter, respectively. The effects of cyromazine were closer to that of chitin synthesis inhibitors rather than that of juvenile hormone analogues, with only 10-20% pupal mortality. The toxicity of cyromazine was not strongly affected by the presence of common resistance mechanism, i.e., Kdr mutation and Ace.1(R) (resistance ratio from 0.5 to 2.3). The absence of cross resistance with common insecticides (pyrethroids, carbamates, organophosphates) makes cyromazine a potential candidate for disease vector control, especially for the management of insecticide resistance.

Spraying of canvas tents with residual pyrethroid insecticide is an established method of malaria vector control in tented refugee camps. In recent years, plastic sheeting (polythene tarpaulins) has replaced canvas as the utilitarian shelter material for displaced populations in complex emergencies. Advances in technology enable polythene sheeting to be impregnated with pyrethroid during manufacture. The efficacy of such material against mosquitoes when erected as shelters under typical refugee camp conditions is unknown. Tests were undertaken with free-flying mosquitoes on entomological study platforms in an Afghan refugee camp to compare the insecticidal efficacy of plastic tarpaulin sprayed with deltamethrin on its inner surface (target dose 30 mg/m2), tarpaulin impregnated with deltamethrin (initially > or = 30 mg/m2) during manufacture, and a tent made from the factory impregnated tarpaulin material. Preliminary tests done in the laboratory with Anopheles stephensi Liston (Diptera: Culicidae) showed that 1-min exposure to factory-impregnated tarpaulins would give 100% mortality even after outdoor weathering in a temperate climate for 12 weeks. Outdoor platform tests with the erected materials (baited with human subjects) produced mosquito mortality rates between 86-100% for sprayed or factory-impregnated tarpaulins and tents (average approximately 40 anophelines and approximately 200 culicines/per platform/night), whereas control mortality (with untreated tarpaulin) was no more than 5%. Fewer than 20% of mosquitoes blood-fed on human subjects under either insecticide-treated or non-treated shelters. The tarpaulin shelter was a poor barrier to host-seeking mosquitoes and treatment with insecticide did not reduce the proportion blood-feeding. Even so, the deployment of insecticide-impregnated tarpaulins in refugee camps, if used by the majority of refugees, has the potential to control malaria by killing high proportions of mosquitoes and so reducing the average life expectancy of vectors (greatly reducing vectorial capacity), rather than by directly protecting refugees from mosquito bites. Mass coverage with deltamethrin-sprayed or impregnated tarpaulins or tents has strong potential for preventing malaria in displaced populations affected by conflict.

Background Public health pesticides has been the mainstay control of vectors of malaria and other diseases, and public health pests, but there is increasing concern over how these pesticides are being managed. Poor pesticide management could lead to risks to human health and the environment, or diminish the effectiveness of interventions. Strategies for strengthening the management of public health pesticides, from manufacture to disposal, should be evaluated to propose future directions. Methods The process and outcomes of three strategies were studied in five regions of the WHO (African Region, Eastern Mediterranean Region, South-East Asia Region, Western Pacific Region, and American Region) and 13 selected countries. These strategies are: regional policy development, in-depth country support and thematic support across countries. Results Consensus, frameworks and action plans on public health pesticide management were developed at regional level. Country support for situation analysis and national action planning highlighted weaknesses over the entire spectrum of pesticide management practices, mainly related to malaria control. The thematic support on pesticide quality control contributed to structural improvements on a priority issue for malaria control across countries. Conclusions The three strategies showed promising and complementary results, but guidelines and tools for implementation of the strategies should be further improved. Increased national and international priority should be given to support the development of policy, legislation and capacity that are necessary for sound management of public health pesticides.

The Eastern Mediterranean Region of the World Health Organization is facing an increasing burden of vector-borne diseases. Progress in controlling these diseases is compromised by the limited number of vector control interventions, most of which rely on the use of pesticides. Seventeen countries of the Region participated in a global survey that aimed to map and document registration and management practices for public health pesticides. This paper aims to draw the attention of policy- and decision-makers to the challenges the Region is facing in managing public health pesticides properly to control disease vectors and, based on the outcome of the survey, recommends a set of actions to guide national policy and to strengthen national capacity for the sound management and judicious use of public health pesticides.

Most insecticides used against pests and vectors of human disease (e.g. fleas, flies and mosquitoes) are spin-offs from agrochemical research and development. The arsenal of safe and cost-effective public health insecticides is being depleted by restrictions for various reasons (e.g. insecticide resistance, unacceptable side effects and non re-registration) and the number of new products launched is dwindling. Mobilizing public resources and establishment of partnerships to support research and development of public health insecticides is crucial in the post-DDT and post-pyrethroid era.

Background It is critical that vector control pesticides are used for their acceptable purpose without causing adverse effects on health and the environment. This paper provides a global overview of the current status of pesticides management in the practice of vector control. Methods A questionnaire was distributed to WHO member states and completed either by the director of the vector-borne disease control programme or by the national manager for vector control. In all, 113 countries responded to the questionnaire (80% response rate), representing 94% of the total population of the countries targeted. Results Major gaps were evident in countries in pesticide procurement practices, training on vector control decision making, certification and quality control of pesticide application, monitoring of worker safety, public awareness programmes, and safe disposal of pesticide-related waste. Nevertheless, basic conditions of policy and coordination have been established in many countries through which the management of vector control pesticides could potentially be improved. Most countries responded that they have adopted relevant recommendations by the WHO. Conclusions Given the deficiencies identified in this first global survey on public health pesticide management and the recent rise in pesticide use for malaria control, the effectiveness and safety of pesticide use are being compromised. This highlights the urgent need for countries to strengthen their capacity on pesticide management and evidence-based decision making within the context of an integrated vector management approach.

Tablet (40 mg a.i./tablet) and granular (2% a.i.) formulations of diflubenzuron, a chitin synthesis inhibitor, insect growth regulator, were evaluated for larvicidal efficacy against the larvae of Aedes aegypti (L.) in water-storage containers under field conditions in Thailand. Each formulation was applied to 200-1 clay jars at 5 different dosages (0.02, 0.05, 0.1, 0.5 and 1 mg/l a.i.). The jars were covered with solid celocrete sheets and placed in the shade under a roof. Another experiment was also carried out using 3 different dosages (0.1, 0.5 and 1 mg/l) where half the water in each treated jar and the control was removed and refilled weekly. Each treatment was replicated four times. The treatments were challenged by adding 25 3rd instar larvae/jar weekly. Assessments were made of each treatment through emergence inhibition (%EI) by removing and counting pupal skins one week after larval addition. Using these assessment techniques, a high degree of larvicidal efficacy (96-100%EI) was achieved with 4 dosages (0.05, 0.1, 0.5 and 1 mg/l) of both (tablet and granular) formulations for a period of 23 weeks post-treatment. The efficacy of the lowest dosage (0.02 mg/l) of tablet and granular formulations lasted for 21 and 22 weeks post-treatment, respectively. Under the conditions of water removal and weekly refilling, a high degree of larvicidal efficacy (96-100%El) at the 3 dosages was obtained with the tablet formulation 18 to 21 weeks post-treatment, whereas the efficacy of the granular formulation persisted 15 to 23 weeks post-treatment depending on the dosage. This study clearly demonstrates a high level of residual activity with both formulations of diflubenzuron against larvae of Ae. aegypti in water-storage containers. Considering environmental factors and water-use conditions, it is likely that dosages of 0.05 to 0.1 mg a.i./l are effective dosages providing long-lasting control for 3 to 4 months in the field.

Toxic and feeding inhibition effect of cyfluthrin treated nets was assessed and compared with the activity of deltamethrin impregnated nets, before and after 2 and 4 washes against Phlebotomus papatasi. Impregnated cyfluthrin nets (50, 25, 12.5 mg active ingredient (a.i.)/m2) caused knock down and mortality rates higher than 90%, being of 100% at the highest dose, while the nets impregnated with deltamethrin (25, 12.5, 6.25 mg a.i./m2) showed low mortality rates (13.3-43.5%). Also after washing cyfluthrin at the dose of 50 mg a.i./m2 provided higher activity than deltamethrin (25 mg a.i./m2), being mortality rates within 24 hs of 66.7 and 48.9% for cyfluthrin and 38.0 and 2.1% for deltamethrin, respectively after 2 and 4 washes. Before washing, cyfluthrin (50 mg a.i./m2) significantly prevented blood feeding, with respect to both untreated (88.6%) and deltamethrin impregnated nets (56.8%). Deltamethrin (25 mg a.i./m2) showed low feeding inhibition (48.4%), although it was significantly higher than control. The washing of cyfluthrin impregnated nets (50 mg a.i./m2) produced a decrease of the feeding inhibition, being the reduction of 26.6% and 41.3%, respectively after 2 and 4 washes. Two washes of deltamethrin impregnated nets (25 mg a.i./m2) yielded a very high reduction of antifeeding inhibition (68.8%). These laboratory results if confirmed by field evaluation indicate cyfluthrin as good candidate for treatment of mosquito nets to be used against phlebotomine sandflies.

Two long-term experiments were carried out on the release profile and efficacy of temephos 1% GR (sand granules) against Aedes aegypti larvae in water-storage containers. In the first experiment, the efficacy of temephos 1% GR enclosed and tied in a muslin cloth and placed in water at the bottom of 200 L earthen water-storage jars was studied by exposing the packets for four to nine wk in one set ofjars and then transferring them sequentially to new sets ofjars four times successively. Temephos released slowly from the granules, the magnitude of release being adequate in the initial period of two to three wk after treatment. Following this period, the efficacy of the granules increased substantially where 92-100% inhibition of emergence even at the lowest dosage of 1 g/100 L (0.05 mg/L AI) was obtained for about another five mo or longer. On removal of the packets from a given set of jars, the released residues remaining in the jars and water lasted a maximum of one to six wk post-removal depending on the magnitude of prior release into the jars. This experiment provided clear evidence that temephos is released slowly over a long period of time in water-storage jars. In the second experiment, we compared the efficacy of temephos 1% GR at 1 and 10 g (0.05 and 0.5 mg/L AI) per 200-L water in jars painted and unpainted on the inside. The efficacy in the painted jars, although high, was consistently lower than that in the unpainted jars, where 99-100% control of larvae was achieved at both rates for a minimum of five mo after treatment. On the basis of this experimental evidence, it is desirable to study the efficacy of lower dosages of temephos than those currently used in Ae. aegypti control programs. The use of controlled release formulations or sachets that are retrievable during cleaning and washing will be more practical and desirable. Both of these interventions will make the program more cost effective.

Because pyrethroid, organophosphate, and carbamate resistance is more and more developed in mosquitoes of medical importance, there is an urgent need for alternative insecticides for vector control. Dinotefuran, a new neonicotinoid insecticide commercialized by Mitsui Chemicals (Tokyo, Japan), could be a useful candidate in public health because it shows low mammalian toxicity and great insecticidal activity against a broad range of pests. In this study, the intrinsic toxicity of dinotefuran was evaluated by larval bioassay and topical application against different mosquito strains of Anopheles gambiae Giles, Culex quinquefasciatus Say, and Aedes aegypti L. having none, one, or several resistance mechanisms, respectively, to insecticides. The results showed that dinotefuran was less toxic than most of the commonly used insecticides (e.g., deltamethrin, carbosulfan, and temephos) against the susceptible mosquitoes tested (between 6- and 100-fold at the LD50 level). However, the toxicity of dinotefuran was not strongly affected by the presence of common resistance mechanism, i.e., kdr mutation and insensitive acetylcholinesterase (resistance ratio [RR] from 1.3 to 2.3). More interestingly, the carbamate-resistant strain of Cx. quinquefasciatus was significantly more affected by dinotefuran than the susceptible strain (RR = 0.70), probably because the insensitive acetylcholinesterase is less efficient to degrade nicotinic substrates than normal acetylcholinesterase. Despite the relatively low toxicity of dinotefuran against susceptible mosquitoes, the absence of cross-resistance with common insecticides (pyrethroids, carbamates, and organophosphates) makes neonicotinoids potential candidates for disease vector control, especially in area where mosquitoes are resistant to insecticides.

Novaluron, a new chitin synthesis inhibitor type of insect growth regulator, was evaluated in the laboratory and field against larvae of the mosquito Aedes aegypti (L.). In the laboratory, the technical material showed a high level of activity against 2nd and 4th instar larvae. The inhibition of emergence (IE) was 100% at concentrations of 0.25 to 1.0 microg/L. Second instars were slightly more susceptible than fourth instars. At the high concentration (1 ppb), most of the mortality occurred in the larvae, but at sublethal concentrations (for larvae) mortality also occurred in pupae and adults (incomplete eclosion). An EC10 (emulsifiable concentrate containing 10% active ingredient) formulation of novaluron was evaluated against Ae. aegypti in water-storage containers in the field in Thailand. Two tests at high (0.05 to 1 mg/L) and low (1 to 20 microg/L) concentrations were carried out in clay jars (200 L) and plastic pails (75 L). At high concentrations in clayjars, we obtained 86-96% inhibition of emergence (IE) for about 190 d, but the mortality declined at low concentrations after 190 d. At much lower concentrations, in jars and plastic pails in the second experiment, the IE was 80-100% for 2 mo. The highest concentrations of this series (10 microg/L in jars and 20 microg/L in pails) were active for 75 and 68 d respectively, losing efficacy by 82 d post-treatment. In the experiment using low concentrations, all treatments in jars and plastic pails failed to provide adequate control 90 d after treatment. These studies show that novaluron, even as EC10, has exceptional long-term activity against Ae. aegypti in water-storage containers, with higher concentrations yielding greater long-term control than low concentrations.

Limited laboratory and field studies have indicated that the insect growth regulator (IGR) novaluron exhibits good activity against larvae of pest species in the orders Coleoptera, Hemiptera (suborder Heteroptera), and Lepidoptera by both ingestion and contact. We completed laboratory and field studies to evaluate activity and efficacy of novaluron against Culex mosquitoes. In laboratory studies, novaluron was highly active against Cx. quinquefasciatus, as indicated by low levels of inhibition of emergency (IE), at the 50% level, IE50 (0.159 ppb for 2nd-stage larvae and 0.118 ppb for 4th-stage larvae) and IE90, at the 90% level, (0.604 ppb for 2nd-stage larvae and 0.595 ppb for 4th-stage larvae). In outdoor microcosm and mesocosm studies against natural populations, novaluron yielded excellent control of immature Culex mosquitoes for up to 14 days at 1.25, 2.5, and 5 ppb in microcosms, and for up to 7 days at the dosages of 1, 5, and 10 mg/m2 in mesocosms. Based on qualitative observations, novaluron seemed to have a favorable margin of safety for nontarget aquatic invertebrates cohabiting with mosquito larvae. Further large-scale field studies are warranted to evaluate initial efficacy and longevity of novaluron against various mosquito species, as well as its safety for nontarget biota.

OBJECTIVE: To compare the efficacy of seven pyrethroid insecticides for impregnation of mosquito nets, six currently recommended by WHO and one candidate (bifenthrin), under laboratory conditions. METHODS: Tests were conducted using pyrethroid-susceptible and pyrethroid-resistant strains of Anopheles gambiae and Culex quinquefasciatus. Knock-down effect, irritancy and mortality were measured using standard WHO cone tests. Mortality and blood-feeding inhibition were also measured using a baited tunnel device. FINDINGS: For susceptible A. gambiae, alpha-cypermethrin had the fastest knock-down effect. For resistant A. gambiae, the knock- down effect was slightly slower with alpha-cypermethrin and much reduced following exposure to the other insecticides, particularly bifenthrin and permethrin. For susceptible C. quinquefasciatus, the knock-down effect was significantly slower than in A. gambiae, particularly with bifenthrin, and no knock-down effect was observed with any of the pyrethroids against the resistant strain. Bifenthrin was significantly less irritant than the other pyrethroids to susceptible and resistant A. gambiae but there was no clear ranking of pyrethroid irritancy against C. quinquefasciatus. In tunnels, all insecticides were less toxic against C. quinquefasciatus than against A. gambiae for susceptible strains. For resistant strains, mortality was significant with all the pyrethroids with A. gambiae but not with C. quinquefasciatus. Inhibition of blood-feeding was also high for susceptible strains of both species and for resistant A. gambiae but lower for resistant C. quinquefasciatus; bifenthrin had the greatest impact. CONCLUSIONS: Efficacy for impregnation of mosquito nets against A. gambiae was greatest with alpha-cypermethrin. Bifenthrin is likely to have a significant comparative advantage over other pyrethroids in areas with pyrethroid resistance because of its much stronger impact on the nuisance mosquito, C. quinquefasciatus, despite its slower knock-down effect and irritancy. Selection of pyrethroids for mosquito vector control and personal protection should take into account the different effects of these insecticides, the status of pyrethroid resistance in the target area, and the importance of nuisance mosquitoes, such as C. quinquefasciatus.

Effectiveness and residual activity tests of granular formulations of 2 insect growth regulators (IGRs), s-methoprene and pyriproxyfen, against laboratory-reared larvae of 5 colonized mosquitoes, Aedes aegypti, Aedes albopictus, Aedes taeniorhynchus, Anopheles quadrimaculatus, and Culex nigripalpus, were conducted in the laboratory and outdoors in plastic tubs. Culex quinquefasciatus was exposed to these two IGRs in the laboratory only. Each IGR formulation was applied at 0.02 and 0.05 ppm active ingredient (Al) against 5 of the 6 mosquito species both in the laboratory and the outdoor evaluations, whereas Cx. quinquefasciatus was exposed to 0.2 and 0.4 ppm AI of s-methoprene, and 0.1 and 0.2 ppm AI of pyriproxyfen in the laboratory. s-Methoprene at 0.02 and 0.05 ppm AI resulted in variable levels (39-100%) of inhibition of adult emergence in the 5 species monitored for 6 weeks after treatment under both test conditions. Aedes taeniorhynchus was the most susceptible to s-methoprene in terms of initial and residual activity. Culex quinquefasciatus and Ae. albopictus were the most tolerant to s-methopene, with maximum emergence inhibitions amounting to 84% in Cx. quinquefasciatus at 0.4 ppm and 44.3% in Ae. albopictus at 0.05 ppm during the 1st week in the laboratory. Pyriproxyfen at comparable treatment rates to s-methoprene caused very high levels (80-100% in most cases) of initial and residual emergence inhibitions of the tested species in the laboratory as well as outdoors. In several species, pyriproxyfen induced complete inhibition of adult emergence for several weeks after treatment, even at the lower rate of 0.02 ppm. The World Health Organization has recently recommended the use of pyriproxyfen for the control of some mosquito species at specified rates in certain habitats.

Bifenthrin, a pyrethroid insecticide already used in agriculture was evaluated in laboratory conditions against susceptible and pyrethroid resistant mosquitoes, as a potential insecticide for treatment of mosquito nets. Two laboratory strains of Anopheles gambiae s.s. Giles, the major malaria vector in Africa, and two of Culex quinquefasciatus Say, a major pest mosquito in urban areas, were used. Compared with other pyrethroids such as permethrin and deltamethrin, the intrinsic toxicity of bifenthrin, measured by topical application with susceptible strains, was intermediate. By forced tarsal contact on filter papers (cylinder tests) or on netting materials (cone tests), bifenthrin was found slightly more effective against A. gambiae than against C. quinquefasciatus, in terms of mortality and knock-down effect. With free flying mosquitoes (tunnel tests), bifenthrin was very efficient in killing mosquitoes and inhibiting blood feeding. Against the two pyrethroid resistant strains, bifenthrin was relatively efficient against A. gambiae but the impact of resistance was greater with C. quinquefasciatus. In tunnel tests, blood feeding remained almost entirely inhibited with the two species despite resistance. The high mortality of susceptible mosquitoes and excellent blood feeding inhibition of susceptible and resistant strains makes bifenthrin a good candidate for treatment of netting materials, particularly in areas where C. quinquefasciatus, the main nuisance in urban areas, is resistant to pyrethroids. The slower knock-down and lower irritant effect also makes this insecticide especially attractive when a mass killing effect on mosquito populations is expected.

The use of insecticide treated nets (ITNs) for personal protection against malaria vector Anopheles mosquitoes (Diptera: Culicidae) has become popular during the past decade. With the precautions outlined in this paper, field use of pyrethroids--at concentrations recommended for treatment of mosquito nets--poses little or no hazard to people treating the nets or to users of the treated nets. With frequent exposure to low concentrations of pyrethroids, the risk of toxicity of any kind is remote. Pyrethroids entering the systemic circulation are rapidly metabolized to much less toxic metabolites. Toxicologically, pyrethroids have a useful characteristic--the production of skin paraesthesia--which gives an early indication of exposure. This reversible symptom of exposure is due to transient stimulation of peripheral sensory nerves and not a toxic effect. In the retail market, for home use, the provision of proper packaging and labelling, with clear instructions on safe and effective use of the product are most important. Because many domestic users of pyrethroid 'home treatment kits' for ITNs may not be fully literate, it is essential that 'instructions for use' should be portrayed via pictograms with supporting text in appropriate local language(s).

Pyrethroid resistant mosquitoes are becoming increasingly common in parts of Africa. It is important to identify alternative insecticides which, if necessary, could be used to replace or supplement the pyrethroids for use on treated nets. Certain compounds of an earlier generation of insecticides, the organophosphates may have potential as net treatments. Comparative studies of chlorpyrifos-methyl (CM), an organophosphate with low mammalian toxicity, and lambdacyhalothrin (L), a pyrethroid, were conducted in experimental huts in Cote d'Ivoire, West Africa. Anopheles gambiae and Culex quinquefasciatus mosquitoes from the area are resistant to pyrethroids and organophosphates (kdr and insensitive acetylcholinesterase Ace.1 R ). Several treatments and application rates on intact or holed nets were evaluated, including single treatments, mixtures, and differential wall/ceiling treatments. All of the treatments were effective in reducing blood feeding from sleepers under the nets and in killing both species of mosquito, despite the presence of the kdr and Ace.1 R genes at high frequency. In most cases, the effects of the various treatments did not differ significantly. Five washes of the nets in soap solution did not reduce the impact of the insecticides on A. gambiae mortality, but did lead to an increase in blood feeding. The three combinations performed no differently from the single insecticide treatments, but the low dose mixture performed encouragingly well indicating that such combinations might be used for controlling insecticide resistant mosquitoes. Mortality of mosquitoes that carried both Ace.1 R and Ace.1 S genes did not differ significantly from mosquitoes that carried only Ace.1 S genes on any of the treated nets, indicating that the Ace.1 R allele does not confer effective resistance to chlorpyrifos-methyl under the realistic conditions of an experimental hut.