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Background Disease surveillance is a cornerstone of outbreak detection and control. Evaluation of a disease surveillance system is important to ensure its performance over time. The aim of this study was to assess the performance of the core and support functions of the Zanzibar integrated disease surveillance and response (IDSR) system to determine its capacity for early detection of and response to infectious disease outbreaks. Methods This cross-sectional descriptive study involved 10 districts of Zanzibar and 45 public and private health facilities. A mixed-methods approach was used to collect data. This included document review, observations and interviews with surveillance personnel using a modified World Health Organization generic questionnaire for assessing national disease surveillance systems. Results The performance of the IDSR system in Zanzibar was suboptimal particularly with respect to early detection of epidemics. Weak laboratory capacity at all levels greatly hampered detection and confirmation of cases and outbreaks. None of the health facilities or laboratories could confirm all priority infectious diseases outlined in the Zanzibar IDSR guidelines. Data reporting was weakest at facility level, while data analysis was inadequate at all levels (facility, district and national). The performance of epidemic preparedness and response was generally unsatisfactory despite availability of rapid response teams and budget lines for epidemics in each district. The support functions (supervision, training, laboratory, communication and coordination, human resources, logistic support) were inadequate particularly at the facility level. Conclusions The IDSR system in Zanzibar is weak and inadequate for early detection and response to infectious disease epidemics. The performance of both core and support functions are hampered by several factors including inadequate human and material resources as well as lack of motivation for IDSR implementation within the healthcare delivery system. In the face of emerging epidemics, strengthening of the IDSR system, including allocation of adequate resources, should be a priority in order to safeguard human health and economic stability across the archipelago of Zanzibar.

Background Effective control of emerging mosquito-borne viral diseases such as dengue, chikungunya, and Zika requires, amongst other things, a functional healthcare system, ready and capable of timely detection and prompt response to incipient epidemics. We assessed the readiness of Zanzibar health facilities and districts for early detection and management of mosquito-borne viral disease outbreaks. Methods A cross-sectional study involving all 10 District Health Management Teams and 45 randomly selected public and private health facilities in Zanzibar was conducted using a mixed-methods approach including observations, document review, and structured interviews with health facility in-charges and District Health Management Team members. Results The readiness of the Zanzibar healthcare system for timely detection, management, and control of dengue and other mosquito-borne viral disease outbreaks was critically low. The majority of health facilities and districts lacked the necessary requirements including standard guidelines, trained staff, real-time data capture, analysis and reporting systems, as well as laboratory diagnostic capacity. In addition, health education programmes for creating public awareness and Aedes mosquito surveillance and control activities were non-existent. Conclusions The Zanzibar healthcare system has limited readiness for management, and control of mosquito-borne viral diseases. In light of impending epidemics, the critical shortage of skilled human resource, lack of guidelines, lack of effective disease and vector surveillance and control measures as well as lack of laboratory capacity at all levels of health facilities require urgent attention across the Zanzibar archipelago.

Background. Bedbug infestation is the worldwide problem according to World Health Organization, and the infestation is characterized by biting reactions including systemic, cutaneous reactions and sometimes psychological disturbance. Prevalence of bedbug infestation is low (6%) in developed countries while in Sierra Leone is 98% and Tanzania is 56% in which is tremendously high. As the bedbug infestation is among neglected conditions and because of high prevalence in Tanzania, the studies to determine this burden, some risk factors (crowding) and awareness among specific populated communities especially schools is inevitable for planning strategies in eradication of bedbug.Objective. To determine the prevalence of bedbug infestation, crowding and awareness level among boarding government secondary school students in Moshi Urban.Methodology. A cross-sectional study was conducted from May to July 2018 at Moshi Urban in Kilimanjaro region. The structured standard questionnaire was used to obtain the demographics information of participants, asses awareness. Personal observation was used to determine prevalence and crowding in the corresponding student’s dormitories. Results. The prevalence of bedbug infestation was 58.1% (223) among 384 study participants. Logistic regression analysis showed that 72.6% of the students with bedbug infestation were found to be living in the overcrowded dormitories. There was association between overcrowd and bedbug infestation (OR=2.50, 95%CI (1.63-3.83) P=0.001. Only 32.7% of the infested students involved in this study were aware with bedbugs (OR=0.8795% CI (0.56-1.35) P=0.54. Conclusion. The overall prevalence of bedbug infestation was found to be high among students living in the overcrowded dormitories and those who were not aware on bedbug biology and behavior, transmission, control and prevention ways. Education concerning bedbugs is needed to increase the community awareness together with management of number of student in accordance to the available facilities and resources.

Aedes aegypti is the main vector for dengue, chikungunya, yellow fever, Zika, and other arboviruses of public health importance. The presence of Ae. aegypti has never been systematically assessed in Zanzibar, including its preferred larval habitats. In 2016 we conducted a cross-sectional entomological survey to describe the preferred larval habitats of Ae. aegypti in Zanzibar City, the main urban area of the Zanzibar archipelago. The surveys for container habitats were conducted for a 17-wk period beginning in January 2016. Immature stages (larvae and pupae) were collected, reared to adulthood, and identified to species. The positive and potential habitats were categorized on the basis of physical, biological, and chemical parameters. A total of 200 samples were collected, of which 124 (62.0%) were positive for immature stages of mosquitoes and 114 (92%) for Ae. aegypti larvae and pupae. Presence of vegetation (odds ratio [OR] = 2.11, 95% confidence interval [CI] = 1.19–3.74), organic matter (OR = 2.37, 95% CI = 1.21–4.60), inorganic matter (OR = 1.78, 95% CI = 1.01–3.13), and sun exposure (OR = 2.34, 95% CI = 1.24–4.36) were all significantly associated with the presence of immature stages of Ae. aegypti, suggesting that these conditions promote colonization of containers. Plastic containers supported 64% of the immature stages and produced approximately 50% of the pupae. Although immature counts were the highest in discarded artifacts, higher pupal counts were found in domestic water storage containers. Our observations suggest that effective control of Ae. aegypti in Zanzibar City must include improved solid waste management (collection and proper disposal of potential container habitats) and reliable supply of domestic water to minimize water-storing practices that provide larval habitats for Ae. aegypti.

Faraja D Ng’ida,1 Gladness L Kotoroi,2 Rose Mwangi,3 Mabula M Mabelele,1 Jovin Kitau,4 Michael J Mahande5,61Department of Epidemiology and Biostatistics, Institute of Public Health, Kilimanjaro Christian Medical University College, Moshi, Tanzania; 2Department of Reader Service, Mzumbe University, Morogoro, Tanzania; 3Department of Epidemiology and Biostatistics, Institute of Public Health, Kilimanjaro Christian Medical University, Moshi, Tanzania; 4Department of Parasitology, Kilimanjaro Christian Medical University College, Moshi, Tanzania; 5Department of Epidemiology & Biostatistics, Institute of Public Health, Kilimanjaro Christian Medical University College, Moshi, Tanzania; 6Department of Community Health, Institute of Public Health, Kilimanjaro Christian Medical Centre, Moshi, TanzaniaBackground: Breast cancer is the leading cause of cancer-related deaths among women globally including Tanzania. However, timely access to diagnosis remains a challenge due to lack of specialized facilities. Most patients presents with advanced stages of the disease making management impossible. This leads to an increase in breast cancer-related mortality. Little is known about knowledge and practices on breast cancer screening in Tanzania. This study described knowledge and practices on breast-cancer detection and associated challenges among women aged 35 years and above in Morogoro rural District in Tanzania.Methods: This descriptive cross-sectional study was conducted in Lubungo, Newland and Fulwe villages at Mikese ward in Morogoro rural District from June and July 2017. A standardized questionnaire was used to obtain information from 130 study participants regarding breast cancer knowledge and practices. Data were analyzed using (SPSS) software version 23 and descriptive statistics were summarized in frequencies and percentages.Results: One hundred and thirty women were studied, all participants have heard of breast cancer; 71.5% knew the effects of breast cancer; 37.7% knew about the signs and symptoms. The most frequently reported cause and risk factor of breast cancer were putting money under brassiere (30.8%) and fat diet (17.7%) respectively. The participants (73.8%) have never heard of breast self-examination (BSE) as an early detection method of breast cancer hence do not practice it. Lack of knowledge on early signs and symptoms of breast cancer was reported as the main challenge for breast cancer screening (73.8%). The frequently reported source of information about this disease was television/radio programs (83.1%).Conclusion: Most of the women have heard of breast cancer but they lack adequate knowledge on its risk factors, causes, symptoms and effects. The majority of the women do not practice BSE due to lack of knowledge. Efforts to improve women’s knowledge on breast cancer is warranted.Keywords: breast cancer detection, knowledge, practices, Tanzania

Objective The aim of the study was to monitor the insecticide susceptibility status of malaria vectors in 12 sentinel districts of Tanzania. Methods WHO standard methods were used to detect knock-down and mortality in the wild female Anopheles mosquitoes collected in sentinel districts. The WHO diagnostic doses of 0.05% deltamethrin, 0.05% lambdacyhalothrin, 0.75% permethrin and 4% DDT were used. Results The major malaria vectors in Tanzania, Anopheles gambiae s.l., were susceptible (mortality rate of 98–100%) to permethrin, deltamethrin, lambdacyhalothrin and DDT in most of the surveyed sites. However, some sites recorded marginal susceptibility (mortality rate of 80–97%); Ilala showed resistance to DDT (mortality rate of 65% [95% CI, 54–74]), and Moshi showed resistance to lambdacyhalothrin (mortality rate of 73% [95% CI, 69–76]) and permethrin (mortality rate of 77% [95% CI, 73–80]). Conclusions The sustained susceptibility of malaria vectors to pyrethroid in Tanzania is encouraging for successful malaria control with Insecticide-treated nets and IRS. However, the emergency of focal points with insecticide resistance is alarming. Continued monitoring is essential to ensure early containment of resistance, particularly in areas that recorded resistance or marginal susceptibility and those with heavy agricultural and public health use of insecticides. Objectif: Surveiller l’etat de la sensibilite aux insecticides des vecteurs du paludisme dans 12 districts sentinelles de la Tanzanie. Methodes: Les methodes standard de l’OMS ont ete utilisees pour mesurer l’inhibition et la mortalite des moustiques anopheles femelles sauvages recueillis dans les districts sentinelles. Les doses diagnostiques OMS de 0,05% pour le deltamethrine, 0,05% pour le lambdacyhalothrine, 0,75% pour la permethrine et 4% pour le DDT ont ete utilisees. Resultats: Les vecteurs majeurs du paludisme en Tanzanie, Anopheles gambiae sl, etaient sensibles (taux de mortalite de 98–100%) a la permethrine, au deltamethrine, au lambdacyhalothrine et au DDT dans la plupart des sites etudies. Cependant, certains sites ont enregistre une sensibilite marginale (taux de mortalite de 80 a 97%). Une resistance au DDT (taux de mortalite de 65% [IC 95%: 54–74]) a ete observee a Ilala et une resistance au lambdacyhalothrine (taux de mortalite de 73% [IC 95%: 69–76]) et a la permethrine (taux de mortalite de 77% [IC 95%: 73–80]) a ete observee a Moshi. Conclusions: La sensibilite maintenue des vecteurs du paludisme aux pyrethrinoides en Tanzanie est encourageante pour la lutte efficace contre le paludisme avec les moustiquaires impregnees et les pulverisations de residus d’interieur. Cependant, l’emergence de foyers avec une resistance aux insecticides est alarmante. La surveillance continue est essentielle pour permettre le confinement precoce de la resistance, en particulier dans les zones qui ont enregistre une resistance ou une sensibilite marginale et celles avec un usage intensif d’insecticides dans la sante publique et agricole. Objetivo: Monitorizar el nivel de susceptibilidad frente a insecticidas de los vectores de malaria en 12 distritos centinela de Tanzania. Metodos: Se utilizaron metodos estandar de la OMS para detectar mosquitos abatidos y mortalidad en hembras anofeles recogidas en los distritos centinela. Se utilizaron las dosis diagnosticas de la OMS de Deltametrina0.05%, Lambdacialotrina 0.05%, Permetrina0.75%, y DDT 4%. Resultados: Los principales vectores de malaria en Tanzania, Anopheles gambiae s.l., eran susceptibles (tasa de mortalidad de 98–100%) a la permetrina, deltametrina, Lambdacialotrina y al DDT en la mayoria de los lugares estudiados. Sin embargo, en algunos de los emplazamientos se registro una susceptibilidad marginal (tasa de mortalidad de 80–97%); en Ilala se observo resistencia al DDT (tasa de mortalidad del 65% [95% IC: 54–74]); y en Moshi se observo resistencia a la Lambdacialotrina (tasa de mortalidad de 73% [95% IC: 69–76]) y permetrina (tasa de mortalidad del 77% [95% IC: 73–80]) Conclusiones: La susceptibilidad sostenida a piretroides de los vectores de malaria en Tanzania es esperanzadora para un control de malaria exitoso con mosquiteras impregnadas y rociamiento intradomiciliario. Sin embargo, la aparicion de puntos focales con resistencia a insecticidas es alarmante. Una monitorizacion continuada es esencial para asegurar el control temprano de la resistencia, particularmente en areas en las que se haya detectado resistencia o susceptibilidad marginal y aquellas con un uso intensivo de insecticidas en agricultura y salud publica.

Background\ud Universal coverage with long-lasting insecticidal mosquito nets (LLIN) or indoor residual spraying (IRS) of houses remain the primary strategies for the control of mosquito vectors of malaria. Pyrethroid resistant malaria vectors are widespread throughout sub-Saharan Africa and new insecticides with different modes of action are urgently needed if malaria vector control is to remain effective. Indoxacarb is an oxadiazine insecticide that is effective as an oral and contact insecticide against a broad spectrum of agricultural pests and, due to its unique site of action, no cross-resistance has been detected through mechanisms associated with resistance to insecticides currently used in public health. \ud \ud Methods\ud WHO tunnel tests of host seeking mosquitoes were carried out as a forerunner to experimental hut trials, to provide information on dosage-dependent mortality, repellency, and blood-feeding inhibition. A dosage range of indoxacarb treated netting (100–1000 mg/m 2 ) was tested against a pyrethroid susceptible strain of Anopheles gambiae. In addition, efficacy of indoxacarb 500 mg/m 2 was compared with a standard pyrethroid formulation against pyrethroid susceptible and resistant Culex quinquefasciatus. Dosages between 25 and 300 mg/m 2 indoxacarb were tested in tunnel tests and in ball-frame bioassays as mixtures with alphacypermethrin 25 mg/m 2 and were compared with singly applied treatments against an insectary reared pyrethroid resistant strain of Cx. quinquefasciatus originally collected in Cotonou, Benin. \ud \ud Results\ud There was a dosage-dependent response in terms of indoxacarb induced mortality, with dosages >100 mg/m 2 producing the best mortality response. In tunnel tests indoxacarb 500 mg/m 2 exceeded WHOPES thresholds with >80 % mortality of adult An. gambiae and blood-feeding inhibition of 75 %. No cross-resistance to indoxacarb was detected through mechanisms associated with resistance to pyrethroid insecticides and was equally effective against susceptible and resistant strains of Cx. quinquefasciatus. Indoxacarb 500 mg/m 2 killed 75 % of pyrethroid resistant Cx. quinquefasciatus compared with only 21 % mortality with alphacypermethrin 40 mg/m 2 . Mixtures of indoxacarb with pyrethroid produced an additive response for both mortality and blood-feeding inhibition. The best performing mixture (indoxacarb 200 mg/m 2 + alphacypermethrin 25 mg/m 2 ) killed 83 % of pyrethroid resistant Cx. quinquefasciatus and reduced blood-feeding by 88 %, while alphacypermethrin only killed 36 % and inhibited blood-feeding by 50 %. \ud \ud Conclusions\ud New insecticides with different modes of action to those currently used in mosquito vector control are urgently needed. Indoxacarb shows great promise as a mixture with a pyrethroid and should be evaluated in experimental hut trials to determine performance against wild free-flying, pyrethroid resistant An. gambiae and wash-resistant formulations developed.

Background\ud The rapid selection of pyrethroid resistance throughout sub-Saharan Africa is a serious threat to malaria vector control. Chlorfenapyr is a pyrrole insecticide which shows no cross resistance to insecticide classes normally used for vector control and is effective on mosquito nets under experimental hut conditions. Unlike neurotoxic insecticides, chlorfenapyr owes its toxicity to disruption of metabolic pathways in mitochondria that enable cellular respiration. A series of experiments explored whether standard World Health Organization (WHO) guidelines for evaluation of long-lasting insecticidal nets, developed through testing of pyrethroid insecticides, are suitable for evaluation of non-neurotoxic insecticides.\ud \ud Methods\ud The efficacy of WHO recommended cone, cylinder and tunnel tests was compared for pyrethroids and chlorfenapyr. To establish bioassay exposure times predictive of insecticide-treated net (ITN) efficacy in experimental hut trials, standard three-minute bioassays of pyrethroid and chlorfenapyr ITNs were compared with longer exposures. Mosquito behaviour and response to chlorfenapyr ITN in bioassays conducted at night were compared to day and across a range of temperatures representative of highland and lowland transmission.\ud \ud Results\ud Standard three-minute bioassay of chlorfenapyr produced extremely low levels of mortality compared to pyrethroids. Thirty-minute day-time bioassay produced mortality closer to hut efficacy of chlorfenapyr ITN but still fell short of the WHO threshold. Overnight tunnel test with chlorfenapyr produced 100% mortality and exceeded the WHO threshold of 80%. The endogenous circadian activity rhythm of anophelines results in inactivity by day and raised metabolism and flight activity by night. A model which explains improved toxicity of chlorfenapyr ITN when tested at night, and during the day at higher ambient temperature, is that activation of chlorfenapyr and disruption of respiratory pathways is enhanced when the insect is more metabolically and behaviourally active.\ud \ud Conclusions\ud Testing according to current WHO guidelines is not suitable for certain types of non-neurotoxic insecticide which, although highly effective in field trials, would be overlooked at the screening stage of evaluation through bioassay. Testing methods must be tailored to the characteristics and mode of action of each insecticide class. The WHO tunnel test on night-active anophelines is the most reliable bioassay for identifying the toxicity of novel insecticides.

BACKGROUND: The Stockholm Convention on Persistent Organic Pollutants (POPs) came into effect in 2004; the use of DDT for malaria control has been allowed to continue under exemption since then due to a perceived absence of equally effective and efficient alternatives. Alternative classes of insecticide for indoor residual spraying (IRS) have a relatively short residual duration of action (2-6 months according to WHO). In areas of year-round transmission multiple spray cycles are required, resulting in significantly higher costs for malaria control programs and user fatigue. This study evaluated performance of a new formulation of deltamethrin (pyrethroid) with polymer (SC-PE) to prolong the effective residual action to >6 months. METHODS: Deltamethrin SC-PE was evaluated alongside an existing water dispersible granule (WG) formulation and DDT water dispersible powder (WP) in laboratory and hut bioassays on mud, concrete, palm thatch and plywood substrates. An experimental hut trial was conducted in Lower Moshi Rice Irrigation Zone, Tanzania from 2008-2009 against wild, free-flying, pyrethroid susceptible An. arabiensis. Performance was measured in terms of insecticide-induced mortality, and blood-feeding inhibition. Bioassays were carried out monthly on sprayed substrates to assess residual activity. RESULTS: Bioassays in simple huts (designed for bioassay testing only) and experimental huts (designed for testing free flying mosquitoes) showed evidence that SC-PE improved longevity on mud and concrete over the WG formulation. Both deltamethrin SC-PE and WG outperformed DDT in bioassays on all substrates tested in the laboratory and simple huts. In experimental hut trials SC-PE, WG and DDT produced high levels of An. arabiensis mortality and the treatments were equivalent over nine months' duration. Marked seasonal changes in mortality were recorded for DDT and deltamethrin treatments, and may have been partly influenced by outdoor temperature affecting indoor resting duration of mosquitoes on sprayed surfaces, although no clear correlation was demonstrated. CONCLUSIONS: There is a limited range of alternative insecticides for IRS, and deltamethrin SC-PE is likely to have an important role as part of a rotation strategy with one or more different insecticide classes rotated annually, particularly in areas that currently have low levels of pyrethroid resistance or low LLIN coverage and year-round malaria transmission.

BACKGROUND: Long-lasting insecticide treated blankets (LLIBs) may provide additional protection against malaria where use of long lasting insecticidal nets (LLIN) is low or impractical such as in disaster or emergency situations. METHODS: Initial efficacy testing of a new candidate LLIB was carried out at LSHTM and KCMUCo, before and after washing, in cone and ball bioassays and arm-in-cage tests against pyrethroid susceptible Anopheles gambiae. A small scale field trial was conducted using veranda-trap experimental huts in northern Tanzania against wild An. arabiensis and Culex quinquefasciatus mosquitoes. Treatments included unwashed and 5 times washed permethrin treated LLIB and blankets hand-treated with permethrin (ITB), untreated blankets, and a holed unwashed Olyset net. RESULTS: Cone test mortality was 75% for LLIB when unwashed, but decreased to 32% after 5 washes and 0.05). Percentage mortality of An. arabiensis in huts with LLIB unwashed (26%) was not statistically different to Olyset net (31%, p = 0.5). The 5 times washed LLIB reduced blood-feeding by 49% which was equivalent to Olyset net (p > 0.086). There was no significant difference in percentage blood-feeding between LLIB and ITB unwashed or 5 times washed (p = 0.147 and p = 0.346 respectively). The 5 times washed LLIB reduced blood-feeding of Culex quinquefasciatus by 40%, although the Olyset provided the greatest protection with 85% inhibition. ELISA analysis of a sub-sample of blood fed mosquitoes showed that not all had fed on humans in the huts, therefore blood-feeding inhibition may have been underestimated. CONCLUSIONS: This trial demonstrated the potential of LLIBs to provide substantial personal protection even against pyrethroid resistant mosquitoes. LLIBs may prove particularly useful where LLINs are unsuitable or net usage is low.

BACKGROUND: Pyrethroid-resistant mosquitoes are an increasing threat to malaria vector control. The Global Plan for Insecticide Resistance Management (GPIRM) recommends rotation of non-pyrethroid insecticides for indoor residual spraying (IRS). The options from other classes are limited. The carbamate bendiocarb and the organophosphate pirimiphos-methyl (p-methyl) emulsifiable concentrate (EC) have a short residual duration of action, resulting in increased costs due to multiple spray cycles, and user fatigue. Encapsulation (CS) technology was used to extend the residual performance of p-methyl. METHODS: Two novel p-methyl CS formulations were evaluated alongside the existing EC in laboratory bioassays and experimental hut trials in Tanzania between 2008-2010. Bioassays were carried out monthly on sprayed substrates of mud, concrete, plywood, and palm thatch to assess residual activity. Experimental huts were used to assess efficacy against wild free-flying Anopheles arabiensis, in terms of insecticide-induced mortality and blood-feeding inhibition. RESULTS: In laboratory bioassays of An. arabiensis and Culex quinquefasciatus both CS formulations produced high rates of mortality for significantly longer than the EC formulation on all substrates. On mud, the best performing CS killed >80% of An. arabiensis for five months and >50% for eight months, compared with one and two months, respectively, for the EC. In monthly bioassays of experimental hut walls the EC was ineffective shortly after spraying, while the best CS formulation killed more than 80% of An. arabiensis for five months on mud, and seven months on concrete. In experimental huts both CS and EC formulations killed high proportions of free-flying wild An. arabiensis for up to 12 months after spraying. There was no significant difference between treatments. All treatments provided considerable personal protection, with blood-feeding inhibition ranging from 9-49% over time. CONCLUSIONS: The long residual performance of p-methyl CS was consistent in bioassays and experimental huts. The CS outperformed the EC in laboratory and hut bioassays but the EC longevity in huts was unexpected. Long-lasting p-methyl CS formulations should be more effective than both p-methyl EC and bendiocarb considering a single spray could be sufficient for annual malaria control. IRS with p-methyl 300 CS is a timely addition to the limited portfolio of long-lasting residual insecticides.

INTRODUCTION: High coverage of conventional and long-lasting insecticide treated nets (ITNs and LLINs) in parts of E Africa are associated with reductions in local malaria burdens. Shifts in malaria vector species ratio have coincided with the scale-up suggesting that some species are being controlled by ITNs/LLINs better than others. METHODS: Between 2005-2006 six experimental hut trials of ITNs and LLINs were conducted in parallel at two field stations in northeastern Tanzania; the first station was in Lower Moshi Rice Irrigation Zone, an area where An. arabiensis predominates, and the second was in coastal Muheza, where An. gambiae and An. funestus predominate. Five pyrethroids and one carbamate insecticide were evaluated on nets in terms of insecticide-induced mortality, blood-feeding inhibition and exiting rates. RESULTS: In the experimental hut trials mortality of An. arabiensis was consistently lower than that of An. gambiae and An. funestus. The mortality rates in trials with pyrethroid-treated nets ranged from 25-52% for An. arabiensis, 63-88% for An. gambiae s.s. and 53-78% for An. funestus. All pyrethroid-treated nets provided considerable protection for the occupants, despite being deliberately holed, with blood-feeding inhibition (percentage reduction in biting rates) being consistent between species. Veranda exiting rates did not differ between species. Percentage mortality of mosquitoes tested in cone bioassays on netting was similar for An. gambiae and An. arabiensis. CONCLUSIONS: LLINs and ITNs treated with pyrethroids were more effective at killing An. gambiae and An. funestus than An. arabiensis. This could be a major contributing factor to the species shifts observed in East Africa following scale up of LLINs. With continued expansion of LLIN coverage in Africa An. arabiensis is likely to remain responsible for residual malaria transmission, and species shifts might be reported over larger areas. Supplementary control measures to LLINs may be necessary to control this vector species.

Malaria morbidity and mortality data from clinical records provide essential information towards defining disease burden in the area and for planning control strategies, but should be augmented with data on transmission intensity and serological data as measures for exposure to mala ria. Theobjective of this study was to estimate the malaria burden based on serological data and prevalence of malaria, and compare it with existing self -treatment practices in Magugu in Babati District of northern Tanzania. Prospectively, 470 individuals were selected for the study. Both microscopy and Rapid Diagnostic Test (RDT) were used for malaria diagnosis. Seroprevalence of antibodies to merozoite surface proteins ( MSP - 119) and apical membrane antigen (AMA-1) was performed and the entomologicalinoculation rate (EIR) was estimated. To complement this information, retrospective data on treatment history, prescriptions by physicians and use of bed nets were collected. Malaria prevalence in the area was 6.8% (32/470). Of 130 individuals treated with art emisinin combination therapy (ACT), 22.3 % (29/130) were slide confirmed while 75.3% (98/130) of them were blood smear negative. Three of the slides confirmed individuals were not treated with ACT. Fever was reported in 38.2% of individuals, ofwhom 48.8 % (88/180) were given ACT. Forty-two (32.3%) of those who received ACT had no history of fever. About half (51.1%) of those treated with ACT were children

A 1-year longitudinal study was conducted in Magugu in Babati district, northern Tanzania to determine malaria vector population structure and malaria transmission indices. Mosquitoes were sampled using the Centre for Disease Control (CDC) light traps. A total of 110,357 adult female mosquitoes were collected. Anopheles gambiae s.1. accounted 25% of the total female mosquito collected. Relatively fewer An. funestus were collected. Other mosquito species collected were An. pharoensis, An. coustani, An. maculipalpis, An. marshallii, Culex quinquefasciatus, Cx unnivittatus, Mansonia uniformis and Ma. africana. An analysis by Polymerase Chain Reaction revealed that An. arabiensis was the only member of the An. gambiae complex in the collected samples. The number of mosquito collected correlated with the increasing mean rainfall. Blood meal analysis showed a higher human enzymatic reaction among An. gambiae s.1. (63.5%) followed by An. funestus (42.9%). Bovine enzymatic reaction was higher among An. coustani (73.7%) followed by the An. pharoensis (66.7%). The Enzyme Linked Immunosorbent Assay (ELISA) was used to detect Plasmodium falciparum circumsporozoites proteins in 10,000 female Anopheles mosquitoes. Only two An. arabiensis were found to be infected. The entomological inoculation rate (EIR) was estimated at 0.51 infectious bites per person per year. This EIR was considered to be relatively low, indicating that malaria transmission in this area is low. Variability in mosquito blood meal shows availability of variety of preferred blood meal choices and impact of other factors inhibiting mosquito-human host contact. The study has provided information considered useful in the mapping of the vector distribution and population structure in the country. Such information is considered to be among the essential tools for planning malaria control interventions.

BACKGROUND: Evolution of insecticide resistance in Anopheles gambiae complex necessitates evaluation of alternative chemical classes to complement existing insecticides for long lasting insecticidal nets (LLIN) and indoor residual spraying (IRS). Microencapsulated (MC) DEET (N, N-diethyl-m-toluamide) is a formulation of the popular repellent, which gives long lasting activity when applied to nets. Its suitability for IRS use has not been evaluated before. This study assessed the efficacy of DEET MC, for IRS in experimental huts. METHODS: DEET MC was tested alongside standard repellent and non-repellent residual insecticides: lambdacyhalothrin, permethrin, pirimiphos methyl and DDT. Residual formulations of these compounds were sprayed on plywood panels attached to walls of experimental huts to assess efficacy against pyrethroid resistant, wild free-flying Anopheles arabiensis and Culex quinquefasciatus. The panel treatments were rotated weekly between huts. RESULTS: The overall mortalities of An. arabiensis induced by the various treatments (range: 76-86%) were significantly greater than mortality in the untreated control (8%, P

Pyrethroid resistant Anopheles gambiae malaria vectors are widespread throughout sub-Saharan Africa and continued efficacy of pyrethroid ITNs is under threat. Chlorfenapyr is a promising pyrrole insecticide with a unique mechanism of action conferring no cross-resistance to existing public health insecticides. Mixtures of chlorfenapyr (CFP) and alphacypermethrin (alpha) may provide additional benefits over chlorfenapyr or alphacypermethrin used alone. An ITN mixture of CFP 100 mg/m(2)+alpha 25 mg/m(2) was compared with CFP 100 mg/m(2) and alpha 25 mg/m(2) in a small-scale experimental hut trial in an area of wild An. arabiensis. The same treatments were evaluated in tunnel tests against insectary-reared pyrethroid susceptible and resistant Culex quinquefasciatus. Performance was measured in terms of insecticide-induced mortality, and blood-feeding inhibition. Tunnel tests showed that mixtures of CFP 100+ alpha 25 were 1.2 and 1.5 times more effective at killing susceptible Cx. quinquefasciatus than either Alpha 25 (P = 0.001) or CFP 100 (P = 0.001) ITNs. Mixtures of CFP100+ alpha 25 were 2.2 and 1.2 times more effective against resistant Cx. quinquefasciatus than either alpha 25 (P = 0.001) or CFP100 (P = 0.003) ITNs. CFP 100+ alpha 25 produced higher levels of blood-feeding inhibition than CFP alone for susceptible (94 vs 46%, P = 0.001) and resistant (84 vs 53%, P = 0.001) strains. In experimental huts the mixture of CFP 100+ Alpha 25 killed 58% of An. arabiensis, compared with 50% for alpha and 49% for CFP, though the differences were not significant. Blood-feeding inhibition was highest in the mixture with a 76% reduction compared to the untreated net (P = 0.001). ITN mixtures of chlorfenapyr and alphacypermethrin should restore effective control of resistant populations of An. gambiae malaria vectors, provide protection from blood-feeding, and may have benefits for resistance management, particularly in areas with low or moderate frequency of pyrethroid resistance. A wash-resistant mixture should be developed urgently.

Background Development of resistance to different classes of insecticides is a potential threat to malaria control. With the increasing coverage of long-lasting insecticide-treated nets in Tanzania, the continued monitoring of resistance in vector populations is crucial. It may facilitate the development of novel strategies to prevent or minimize the spread of resistance. In this study, metabolic-based mechanisms conferring permethrin (pyrethroid) resistance were investigated in Anopheles arabiensis of Lower Moshi, Kilimanjaro region of north-eastern Tanzania. Methods WHO susceptibility test kits were used to detect resistance to permethrin in An. arabiensis. The levels and mechanisms of permethrin resistance were determined using CDC bottle bioassays and microplate (biochemical) assays. In bottle bioassays, piperonyl butoxide (PBO) and s,s,s-tributyl phosphorotrithioate (DEF) were used as synergists to inhibit mixed function oxidases and non-specific esterases respectively. Biochemical assays were carried out in individual mosquitoes to detect any increase in the activity of enzymes typically involved in insecticide metabolism (mixed function oxidases, α- and β-esterases). Results Anopheles arabiensis from the study area was found to be partially resistant to permethrin, giving only 87% mortality in WHO test kits. Resistance ratios at KT50 and KT95 were 4.0 and 4.3 respectively. The permethrin resistance was partially synergized by DEF and by PBO when these were mixed with permethrin in bottle bioassays and was fully synergized when DEF and PBO were used together. The levels of oxidase and β-esterase activity were significantly higher in An. arabiensis from Lower Moshi than in the laboratory susceptible strain. There was no difference in α-esterase activity between the two strains. Conclusion Elevated levels of mixed function oxidases and β-esterases play a role in detoxification of permethrin in the resistant An. arabiensis population of Lower Moshi.