Routine implementation costs of larviciding with Bacillus thuringiensis israelensis against malaria vectors in a district in rural Burkina Faso.

BACKGROUND: The key tools in malaria control are early diagnosis and treatment of cases as well as vector control. Current strategies for malaria vector control in sub-Saharan Africa are largely based on long-lasting insecticide-treated nets (LLINs) and to a much smaller extent on indoor residual spraying (IRS). An additional tool in the fight against malaria vectors, larval source management (LSM), has not been used in sub-Saharan Africa on a wider scale since the abandonment of environmental spraying of DDT. Increasing concerns about limitations of LLINs and IRS and encouraging results from large larvicide-based LSM trials make a strong case for using biological larviciding as a complementary tool to existing control measures. Arguments that are often quoted against such a combined approach are the alleged high implementation costs of LSM. This study makes the first step to test this argument. The implementation costs of larval source management based on Bacillus thuringiensis israelensis (Bti) (strain AM65-52) spraying under different implementation scenarios were analysed in a rural health district in Burkina Faso. METHODS: The analysis draws on detailed cost data gathered during a large-scale LSM intervention between 2013 and 2015. All 127 villages in the study setup were assigned to two treatment arms and one control group. Treatment either implied exhaustive spraying of all available water collections or targeted spraying of the 50 % most productive larval sources via remote-sensing derived and entomologically validated risk maps. Based on the cost reports from both intervention arms, the per capita programme costs were calculated under the assumption of covering the whole district with either intervention scenario. Cost calculations have been generalized by providing an adaptable cost formula. In addition, this study assesses the sensitivity of per capita programme costs with respect to changes in the underlying cost components. RESULTS: The average annual per capita costs of exhaustive larviciding with Bti during the main malaria transmission period (June-October) in the Nouna health district were calculated to be US$ 1.05. When targeted spraying of the 50 % most productive larval sources is used instead, average annual per capita costs decrease by 27 % to US$ 0.77. Additionally, a high sensitivity of per capita programme costs against changes in total surface of potential larval sources and the number of spraying repetitions was found. DISCUSSION: The per capita costs for larval source management interventions with Bti are roughly a third of the annual per capita expenditures for anti-malarial drugs and those for LLINs in Burkina Faso which are US$ 3.80 and 3.00, respectively. The average LSM costs compare to those of IRS and LLINs for sub-Saharan Africa. The authors argue that in such a setting LSM based on Bti spraying is within the range of affordable anti-malarial strategies and, consequently, should deserve more attention in practice. Future research includes a cost-benefit calculation, based on entomological and epidemiological data collected during the research project.

Challenges of implementing a large scale larviciding campaign against malaria in rural Burkina Faso - lessons learned and recommendations derived from the EMIRA project.

BACKGROUND: Recent malaria control and elimination attempts show remarkable success in several parts of sub-Saharan Africa. Vector control via larval source management represents a new and to date underrepresented approach in low income countries to further reduce malaria transmission. Although the positive impact of such campaigns on malaria incidence has been researched, there is a lack of data on which prerequisites are needed for implementing such programs on a routine basis on large scale. Our objectives are to point out important steps in implementing an anti-malaria larviciding campaign in a resource and infrastructure restraint setting and share the lessons learned from our experience during a three-year intervention study in rural Burkina Faso. METHODS: We describe the approaches we followed and the challenges that have been encountered during the EMIRA project, a three-year study on the impact of environmental larviciding on vector ecology and human health. An inventory of all performed work packages and associated problems and peculiarities was assembled. RESULTS: Key to the successful implementation of the larviciding program within a health district was the support and infrastructure from the local research center run by the government. This included availability of trained scientific personnel for local project management, data collection and analysis by medical personnel, entomologists and demographers and teams of fieldworkers for the larviciding intervention. A detailed a priori assessment of the environment and vector breeding site ecology was essential to calculate personnel requirements and the need for larvicide and application apparel. In our case of a three-year project, solid funding for the whole duration was an important issue, which restricted the number of possible donors. We found the acquisition of qualified field personnel in fair numbers not to be always easy and training in application techniques and basic entomologic knowledge required several weeks of theoretical and practical formation. A further crucial point was to establish an effective quality control system that ensured the timely verification of larviciding success and facilitated in time data handling. While the experiences of running a larviciding campaign may vary globally, the experiences gained and the methods used in the Nouna health district may be employed in similar settings. CONCLUSIONS: Our observations highlight important components and strategies that should be taken into account when planning and running a similar larviciding program against malaria in a resource limited setting. A strong local partnership, meticulous planning with the possibility of ad-hoc adaption of project components and a reliable source of funding turned out to be crucial factors to successfully accomplish such a project.

Anopheles (Anopheles) petragnani Del Vecchio 1939-a new mosquito species for Germany.

The so far known species of the Anopheles Claviger Complex, Anopheles claviger s.s. and Anopheles petragnani, can only be distinguished by partial overlapping characteristics of immature stages and by nucleotide sequence variation of the genomic ribosomal DNA (rDNA) internal transcribed spacer 2 (ITS2) region. The known distribution of An. petragnani is so far restricted to the western Mediterranean region, whereas An. claviger s.s. occurs across most of Europe, up to the Middle East and North Africa. In our study, we investigated the larval mosquito fauna in rock pools of the Murg valley (Black Forest, Germany) once a month from April to December 2015.Among other species, larvae belonging to the Anopheles Claviger Complex were found. The fourth instar larvae were morphologically identified by chaetotaxy of the head and abdomen. The results were confirmed by a multiplex PCR and additional sequencing of the amplificates.Of the 1289 collected larvae from the rock pools, seven belonged to the Anopheles Claviger Complex. Five individuals were determined morphologically as An. petragnani and two as An. claviger s.s. The associated mosquito fauna comprised of Aedes japonicus japonicus (548 individuals), Culex pipiens s.l. and Culex torrentium (493 individuals) and Culex hortensis (241 individuals).This is the first record of An. petragnani north of the Alps. Further studies will reveal whether this is an isolated population of An. petragnani and if the investigated rock pool breeding sites represent typical habitats of this species in temperate regions in Central Europe.

Illustrated keys to the anopheline mosquitoes of Myanmar.

In the newly revised and illustrated keys to 4th instar larvae and adult female mosquitoes, the following 36 Anopheles species from Myanmar are included: Anopheles aconitus, An. aitkenii, An. annularis, An. argyropus, An. barbirostris, An. bengalensis, An. culicifacies, An. dirus, An. fluviatilis, An. gigas, An. insulaeflorum, An. jamesii, An. jeyporensis, An. karwari, An. kochi, An. kyondawensis, An. lindesayi, An. maculatus, An. majidi, An. minimus, An. nigerrimus, An. nitidus, An. pallidus, An. peditaeniatus, An. philippinensis, An. pseudojamesii, An. sinensis, An. splendidus, An. stephensi, An. subpictus, An. sundaicus, An. tessellatus, An. theobaldi, An. vagus, An. varuna, and An. willmori. The new keys presented in this paper will enable public health workers to rapidly identify mosquito vectors of malaria and to distinguish them from other species in the same genera.

Pilot longitudinal mosquito surveillance study in the Danube Delta Biosphere Reserve and the first reports of Anopheles algeriensis Theobald, 1903 and Aedes hungaricus Mihályi, 1955 for Romania.

BACKGROUND: Mosquito-borne viruses (moboviruses) are of growing importance in many countries of Europe. In Romania and especially in the Danube Delta Biosphere Reserve (DDBR), mosquito and mobovirus surveillance are not performed on a regular basis. However, this type of study is crucially needed to evaluate the risk of pathogen transmission, to understand the ecology of emerging moboviruses, or to plan vector control programmes. METHODS: We initiated a longitudinal mosquito surveillance study with carbon dioxide-baited Heavy Duty Encephalitis Vector Survey traps at four sampling sites to analyse the spatio-temporal pattern of the (i) mosquito species composition and diversity, (ii) functional groups of mosquitoes (oviposition sites, overwintering stage, and number of generations), and (iii) the occurrence of potential West Nile virus (WNV) vectors. RESULTS: During 2014, a total of 240,546 female mosquitoes were collected. All species were identified using morphological characteristics and further confirmed by mitochondrial cytochrome c oxidase subunit I (COI) gene analysis of selected specimens. The two most common taxa were Coquilettidia richiardii (40.9 %) and Anopheles hyrcanus (34.1 %), followed by Culex pipiens (sensu lato) (s.l.)/Cx. torrentium (7.7 %), Aedes caspius (5.7 %), Cx. modestus (4.0 %), An. maculipennis (s.l.) (3.9 %), and Ae. vexans (3.0 %). A further seven species were less common in the area studied, including two new records for Romania: An. algeriensis and Ae. hungaricus. Phylogenetic analysis of COI gene demonstrated the evolutionary relatedness of most species with specimens of the same species collected in other European regions, except Ae. detritus and An. algeriensis, which exhibited high genetic diversity. Due to the dominance of Cq. richiardii and An. hyrcanus (75 % of all collected specimens), the overall phenology and temporal pattern of functional groups basically followed the phenology of both species. A huge proportion of the mosquito population in the course of the entire sampling period can be classified as potential WNV vectors. With 40 % of all collected specimens, the most frequent species Cq. richiardii is probably the most important vector of WNV in the DDBR. CONCLUSION: This is the first DNA-barcoding supported analysis of the mosquito fauna in the DDBR. The detection of two new species highlights the lack of knowledge about the mosquito fauna in Romania and in the DDBR in particular. The results provide detailed insights into the spatial-temporal mosquito species composition, which might lead to a better understanding of mobovirus activity in Romania and thus, can be used for the development of vector control programs.

EMIRA: Ecologic Malaria Reduction for Africa--innovative tools for integrated malaria control.

BACKGROUND: Malaria control is based on early treatment of cases and on vector control. The current measures for malaria vector control in Africa are mainly based on long-lasting insecticide treated nets (LLINs) and to a much smaller extent on indoor residual spraying (IRS). A third pillar in the fight against the malaria vector, larval source management (LSM), has virtually not been used in Africa since the ban of DDT in the 1960s. Within the light of recent WHO recommendations for Bacillus thuringiensis israelensis (Bti) use against malaria and other vector species, larval source management could see a revival in the upcoming years. In this project we analyze the ecologic and health impacts as well as the cost effectiveness of larval source management under different larviciding scenarios in a health district in Burkina Faso. METHODS: The project is designed as prospective intervention study with duration of three years (2013-2015). Its spatial scale includes three arms of interventions and control, comprising a total of 127 villages and the district capital Nouna in the extended HDSS (Health Demographic Surveillance System) of the Kossi province. Baseline data on mosquito abundance, parasitemia in U5 children, and malaria related morbidity and mortality are gathered over the project duration. Besides the outcome on ecologic and health parameters, the economic costs are seized and valued against the achieved health benefits. CONCLUSIONS: Risk map based, guided larvicide application might be a possibility to further decrease economic cost of LSM and facilitate its faster incorporation to integrated malaria control programs. Given the limited resources in many malaria endemic countries, it is of utmost importance to relate the costs of novel strategies for malaria prevention to their effect on the burden of the disease. Occurring costs and the impact on the health situation will be made comparable to other, existing intervention strategies, allowing stakeholders and policymakers decision making.

Efficacy of Bacillus thuringiensis var. israelensis against malaria mosquitoes in northwestern Burkina Faso.

BACKGROUND: In Sub Saharan Africa malaria remains one of the major health problems and its control represents an important public health measure. Integrated malaria control comprises the use of impregnated mosquito nets and indoor residual spraying. The use of drugs to treat patients can create additional pressure on the equation of malaria transmission. Vector control may target the adult mosquitoes or their aquatic larval stages. Biological larvicides such as Bacillus thuringiensis israelensis (Bti) represent a promising approach to support malaria control programs by creating additional pressure on the equation of malaria transmission. METHODS: In this study we examined the efficacy of a water-dispersible granule formulation (WDG) of the biological larvicide Bti (VectoBac®) against wild Anopheles spp. larvae. Different concentrations of the larvicide were tested in standardized plastic tubs in the field against untreated controls. In weekly intervals tubs were treated with fixed concentrations of larvicide and the percentage reduction of larvae and pupae was calculated. RESULTS: All used concentrations successfully killed 100 percent of the larvae within 24 hours, while the higher concentrations showed a slightly prolonged residual effect. Natural reconolization of larvae took place after two and three days respectively, late instar larvae were not found before 5 days after treatment. For the higher concentrations, up to three days no new larvae were found, implicating that the residual effect of WDG in tropical conditions is approximately one to two days. The overall pupae reduction in treated tubs was 98.5%. CONCLUSIONS: Biological larviciding with Bti can be a promising, additional tool in the fight against malaria in Africa. Environmental particularities in tropical Africa, first and foremost the rapid development of mosquitoes from oviposition to imago have to be taken into account before implementing such counter measures in national or international vector control programs. Nonetheless biological larviciding seems to be an appropriate measure for selected conditions, offering a significant contribution to the future of malaria control.

Mosquito fauna and perspectives for integrated control of urban vector-mosquito populations in Southern Benin (West Africa).

This study aims at an integrated vector management (IVM) concept of implementing biological control agents against vector mosquito larvae as a cost-effective and scalable control strategy. In the first step, the mosquito species composition fauna of southern Benin was studied using standard entomological procedures in natural and man-made habitats. Altogether, 24 species belonging to 6 genera of mosquitoes Aedes, Anopheles, Culex, Mansonia, Uranotaenia, Ficalbia were recorded. Five species, Cx. thalassius, Cx. nebulosus, Cx. perfuscus, Cx. pocilipes and Fi. mediolineata are described the first time for Benin. The local mosquito species showed high susceptibility to a Bacillus sphaericus formulation (VectoLex(R) WDG ) in a standardized field test. A dosage of 1 g/m(2) was effective to achieve 100 percent mortality rate for Cx. quinquefasciatus late instar larvae in a sewage habitat, with a residual effect of up to 7 days. After more than 1 year of baseline data collection, operational larviciding with B. thuringiensis var. israelensis and B. sphaericus was commenced in 2006 in selected areas. Microbial insecticides products for larval control show great potential within IVM programmes and may augment control efforts against adult insects, such as the use of insecticide-treated bed nets or indoor wall spraying in many parts of Africa.