Insecticide susceptibility status of human biting mosquitoes in Muheza, Tanzania

Background: There has been a rapid emergence in insecticide resistance among mosquito population to commonly used public health insecticides. This situation presents a challenge to chemicals that are currently used to control mosquitoes in sub-Saharan African. Furthermore, there is limited information on insecticide susceptibility status of human-biting mosquitoes in some areas of Tanzania. This study aimed to determine insecticide susceptibility status of human biting mosquitoes in a rural area of north-eastern Tanzania.Methods: The study was conducted in two villages in Muheza district, Tanzania. Insecticide susceptibility bioassays were performed according to the World Health Organization standard operating procedures on two to five-day old human biting mosquitoes. The mosquitoes of each species were exposed to four classes of insecticides commonly used for malaria vector control. Mosquito mortality rates (%) were determined after 24 hours post insecticide exposure.Results: Mosquito species tested were Anopheles gambiae s.l., An. funestus, Aedes aegypti, and Culex quinquefasciatus species. Real-time PCR have showed that the main sibling species of An. gambiae complex and An. funestus group were An. gambiae s. s. (58.2%) and An. funestus s. s. (91.1%), respectively. All mosquitoes, except Ae. aegypti formosus were susceptible to pirimiphos-methyl (0.25%). An. gambiae s. l. was found to be resistant to permethrin (0.75%) but showed possibility of resistance to DDT (4%) and bendiocarb (0.1%). Our findings have shown that, An. funestus was fully susceptible to all insecticide tested.Conclusion: The present study has revealed different levels of insecticide susceptibility status to four classes of commonly used insecticides in the most common mosquito vectors of human diseases in north-eastern Tanzania. The findings of the present study call for integrated vector control interventions.

La cultura dei materiali e il lato sensoriale del progetto / The material cultures and the sensory side of the project

L’ambito della cultura dei materiali per il design, oggi, si presenta quale disciplina variegata e multiforme: tale contesto, infatti, è studiato attraverso metodi, metodologie e approcci differenti, appartenenti a scienze e saperi spesso anche distanti tra loro, quali discipline delle aree tecnico-scientifiche e discipline umanistiche. I materiali (per il progetto) sono infatti indagati principalmente da due tipi di conoscenze, la prima più tecnica e la seconda più estetico-sensoriale. L’articolo si focalizzerà su quest’ultima, porgendo particolare attenzione ai sensi del tatto, dell’udito e dell’olfatto, quali “strumenti” per il progettista per la progettazione corretta della loro user experience, della percezione, emozione e reazione che una persona prova quando si interfaccia con essi. / Today, the field of the culture of materials for design is a variegated and multi-form discipline: this context, in fact, is investigated through different methods, methodologies and approaches, belonging to sciences and knowledge that are often very distant from each other, such as disciplines of technical-scientific areas and humanities. The materials (for the project) are, in fact, investigated mainly by two types of knowledge, a more technical one and a more aesthetic-sensorial one. The article will focus on the latter, paying particular attention to the senses of touch, hearing and smell, as “tools” for the designer looking for the correct design of their user experience, perception, emotion and reaction when interfacing with them

The Effectiveness of Non-pyrethroid Insecticide-treated Durable Wall Lining to Control Malaria in Rural Tanzania: Study Protocol for a Two-armed Cluster Randomized Trial.

Despite considerable reductions in malaria achieved by scaling-up long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS), maintaining sustained community protection remains operationally challenging. Increasing insecticide resistance also threatens to jeopardize the future of both strategies. Non-pyrethroid insecticide-treated wall lining (ITWL) may represent an alternate or complementary control method and a potential tool to manage insecticide resistance. To date no study has demonstrated whether ITWL can reduce malaria transmission nor provide additional protection beyond the current best practice of universal coverage (UC) of LLINs and prompt case management. A two-arm cluster randomized controlled trial will be conducted in rural Tanzania to assess whether non-pyrethroid ITWL and UC of LLINs provide added protection against malaria infection in children, compared to UC of LLINs alone. Stratified randomization based on malaria prevalence will be used to select 22 village clusters per arm. All 44 clusters will receive LLINs and half will also have ITWL installed on interior house walls. Study children, aged 6 months to 11 years old, will be enrolled from each cluster and followed monthly to estimate cumulative incidence of malaria parasitaemia (primary endpoint), time to first malaria episode and prevalence of anaemia before and after intervention. Entomological inoculation rate will be estimated using indoor CDC light traps and outdoor tent traps followed by detection of Anopheles gambiae species, sporozoite infection, insecticide resistance and blood meal source. ITWL bioefficacy and durability will be monitored using WHO cone bioassays and household surveys, respectively. Social and cultural factors influencing community and household ITWL acceptability will be explored through focus-group discussions and in-depth interviews. Cost-effectiveness, compared between study arms, will be estimated per malaria case averted. This protocol describes the large-scale evaluation of a novel vector control product, designed to overcome some of the known limitations of existing methods. If ITWL is proven to be effective and durable under field conditions, it may warrant consideration for programmatic implementation, particularly in areas with long transmission seasons and where pyrethroid-resistant vectors predominate. Trial findings will provide crucial information for policy makers in Tanzania and other malaria-endemic countries to guide resource allocations for future control efforts

Impact of non-pyrethroid insecticide treated durable wall lining on age structure of malaria vectors in Muheza, Tanzania

Abstract Objective Malaria vectors control interventions are designed to cause immediate killing or shorten mosquito lives, therefore does not allow enough time for the development of the parasites to infective stage. The wall lining is new malaria vectors control intervention in Tanzania where its impact on age structure is not well known. Therefore this study aimed at determining the impact of non-pyrethroid durable wall lining on the age structure of malaria vectors. Results Higher proportions of An. gambiae sensu lato (57.1%, z = 2.66, P = 0.0077) and An. funestus (64.8%, z = 3.38, P = 0.001) were collected in the control clusters. Unexpectedly, significantly higher proportion of parous An. gambiae s. l. were collected in the intervention clusters (z = − 2.78, P = 0.0054). The wall lining intervention has demonstrated low impact on age structure of An. gambiae s. l., this call for further studies on the efficacy of the intervention

Effect of physicochemical parameters on Anopheles and Culex mosquito larvae abundance in different breeding sites in a rural setting of Muheza, Tanzania

Abstract Background Malaria and lymphatic filariasis (LF) are diseases of great public health important in East Africa. Malaria is transmitted by Anopheles while LF is transmitted by both Anopheles and Culex mosquitoes. There is limited evidence on the effects of physicochemical parameters on these mosquitoes in rural settings of Tanzania. This study aimed at assessing the effects of physicochemical parameters on Anopheles and Culex larvae abundance in different breeding sites in a rural setting of Muheza district. Methods A cross-sectional study was conducted in 13 villages in Muheza district, between December 2015 and May 2016. Mosquito larvae were sampled using standard dipping techniques. Physicochemical parameters were measured by a Multi-parameter pH meter in different mosquito breeding sites. Mosquito larvae and pupa densities were compared between the ≤33th (lower) and ≥67th (upper) percentiles of physicochemical parameters. An. gambiae (s.l.) and An. funestus were identified by polymerase chain reaction (PCR) to reveal their sibling species. Results Abundance of Anopheles larvae was significantly higher (76.6%) than Culex (66.9%) χ 2 = 5.73, df = 1, P = 0.017). The presence of late instars of Anopheles was significantly higher (78.2%) than that of Culex (64.5%) (χ 2 = 0.984, df = 1, P = 0.017). A model adjusted for larval stage showed that the likelihood of finding Culex larvae was lower by 38.2% (95% CI: 16.9–54.1, df = 1, P = 0.001) compared to Anopheles. Upper percentiles of salinity (OR = 7.05; 95% CI: 1.19–41.88, P = 0.032) and conductivity (OR = 5.47; 95% CI: 1.01–29.67, P = 0.056) were significantly associated with the presence and with increased density of Anopheles larvae. PCR results showed that, within the gambiae complex, 53.3% (n = 136) were An. gambiae (s.s.) and 46.7% (n = 119) were An. arabiensis. In An. funestus group, 91.1% (n = 41) were An. funestus (s.s.), 4.4% (n = 2) were An. rivulorum, 2.2% (n = 1) were An. leesoni and 2.2% (n = 1) were An. parensis. Conclusion High salinity and conductivity were significantly associated with increased density of Anopheles larvae. To our knowledge, this is the first study to demonstrate the occurrence of Anopheles larvae in polluted breeding sites in rural settings of Tanzania. The study has found both Anopheles and Culex mosquito larvae co-existed in breeding sites. The possible reasons for tolerance to a higher level of physicochemical parameters among Anopheles mosquitoes need to be ascertained

Cross-sectional Survey on Antibiotic Prescription Practices Among Health Care Providers in Rombo District, Northern Tanzania

Background: Irrational and inappropriate antibiotic prescription is a worldwide phenomenon – increasing the threat of serious antibiotic resistance. A better understanding of health care providers’ knowledge, attitudes, and prescription practices related to antibiotics is essential for formulating effective antibiotics stewardship programmes. The aim of the present study was to assess knowledge, attitudes, and prescription practices toward antibiotics among health care providers.   Methods: A descriptive cross-sectional study was conducted between March and June 2017 to assess knowledge, attitudes, and prescription practices toward antibiotics among health care providers in the Rombo district of northern Tanzania. A total of 217 health care providers were interviewed using a structured questionnaire.   Results: Over half of health care providers (n=111, 51.2%) strongly agreed that the inappropriate prescription of antibiotics puts patients at risk. More than half (n=112, 51.6%) reported that their decision to start antibiotic therapy was influenced by a patient’s clinical condition, while 110 (50.7%) reported they were influenced by positive microbiological results in symptomatic patients. Almost two-thirds of the health care providers (n=136, 62.7%) reported that they had access to and used antibiotic therapy guidelines. Less than a quarter (n=52, 24.0%) received regular training and education in antibiotic prescription practice in their work place.   Conclusion: Knowledge and prescription practice of antibiotics among health care providers was generally unsatisfactory. Training and education for health care providers is needed in the area of prescribing antibiotics