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Lekei E.E.,Tropical Pesticides Research Institute | Ngowi A.V.,Muhimbili University of Health and Allied Sciences
BMC Public Health | Year: 2014

Background: Pesticides in Tanzania are extensively used for pest control in agriculture. Their usage and unsafe handling practices may potentially result in high farmer exposures and adverse health effects.The aim of this study was to describe farmers' pesticide exposure profile, knowledge about pesticide hazards, experience of previous poisoning, hazardous practices that may lead to Acute Pesticide Poisoning (APP) and the extent to which APP is reported. Methods. The study involved 121 head- of-household respondents from Arumeru district in Arusha region. Data collection involved administration of a standardised questionnaire to farmers and documentation of storage practices. Unsafe pesticide handling practices were assessed through observation of pesticide storage, conditions of personal protective equipment (PPE) and through self-reports of pesticide disposal and equipment calibration. Results: Past lifetime pesticide poisoning was reported by 93% of farmers. The agents reported as responsible for poisoning were Organophosphates (42%) and WHO Class II agents (77.6%).Storage of pesticides in the home was reported by 79% of farmers. Respondents with higher education levels were significantly less likely to store pesticides in their home (PRR High/Low = 0.3; 95% CI = 0.1-0.7) and more likely to practice calibration of spray equipment (PRR High/Low = 1.2; 95% CI = 1.03-1.4). However, knowledge of routes of exposure was not associated with safety practices particularly for disposal, equipment wash area, storage and use of PPE. The majority of farmers experiencing APP in the past (79%) did not attend hospital and of the 23 farmers who did so in the preceding year, records could be traced for only 22% of these cases. Conclusions: The study found a high potential for pesticide exposure in the selected community in rural Tanzania, a high frequency of self-reported APP and poor recording in hospital records. Farmers' knowledge levels appeared to be unrelated to their risk. Rather than simply focusing on knowledge-based strategies, comprehensive interventions are needed to reduce both exposure and health risks, including training, improvements in labeling, measures to reduce cost barriers to the adoption of safe behaviours, promotion of control measures other than PPE and support for Integrated Pest Management (IPM). © 2014 Lekei et al.; licensee BioMed Central Ltd.


Lekei E.,Tropical Pesticides Research Institute | Ngowi A.V.,Muhimbili University of Health and Allied Sciences
NeuroToxicology | Year: 2014

Background and aim: Acute pesticide poisoning (APP), particularly with neurotoxic agents, is often under-reported in developing countries. This study aimed to estimate the burden of APP in Tanzania due to neurotoxic and other pesticides in order to propose a surveillance system. Methods: The study reviewed hospital admission data for APP retrospectively (2000-2005) in 30 facilities in four regions of Tanzania. A prospective follow-up over 12 months in 2006 focused on 10 facilities with the highest reporting of APP. Results: The majority of known poisoning agents were organophosphates or WHO class I and II pesticides. APP involving suicide was significantly more likely to be fatal in both retrospective (PRR fatal/non-fatal = 3.8; 95% CI = 1.8-8.0) and in prospective (PRR = 8.7; 95% CI = 1.1-65) studies. There was a significant association between suicide and gender (PRR female/male = 1.5; 95% CI = 1.1-2.0) in the prospective study. Occupational circumstances as a cause of APP, which was relatively small in both studies (8.5% in the retrospective and 10.2% in the prospective study) was less common amongst men compared to women (6.1% for males versus 12.0% for females) in the retrospective study but almost equal in prospective study (10.2% for males versus 10.1% for females). Contrasting retrospective to prospective studies, the annual incidence rate almost tripled (from 1.43 to 4.05 per 100,000) and mortality rate doubled (from 0.11 to 0.22 per 100,000). Case fatality declined accordingly from 7.8% to 5.6% in prospective study. The study revealed a substantial improvement in the completeness of data with prospective data collection. Missing data for circumstances and agents declined by 24.1% and 9.9%, respectively. Despite this improvement, routine reporting could only generate 33-50% of the information needed for a notification of banned or severely restricted chemicals under the Prior Informed Consent (PIC) convention. Conclusion: The two to threefold increase in rates with prospective data collection suggests significant under-reporting of APP by neurotoxic and other pesticides. Routine reporting is likely to under-estimate the burden from pesticides, particularly for women in occupational settings. The burden of APP and the specific pesticides causing serious problems in Tanzania would continue to be missed without improved surveillance systems. © 2014 Elsevier Inc.


Gilbreath T.M.,University of California at Irvine | Kweka E.J.,Tropical Pesticides Research Institute | Afrane Y.A.,Kenya Medical Research Institute | Githeko A.K.,Kenya Medical Research Institute | Yan G.,University of California at Irvine
Parasites and Vectors | Year: 2013

Background: In sub-Saharan Africa, malaria, transmitted by the Anopheles mosquito, remains one of the foremost public health concerns. Anopheles gambiae, the primary malaria vector in sub-Saharan Africa, is typically associated with ephemeral, sunlit habitats; however, An. gambiae larvae often share these habitats with other anophelines along with other disease-transmitting and benign mosquito species. Resource limitations within habitats can constrain larval density and development, and this drives competitive interactions among and between species. Methods. We used naturally occurring stable isotope ratios of carbon and nitrogen to identify resource partitioning among co-occurring larval species in microcosms and natural habitats in western Kenya. We used two and three source mixing models to estimate resource utilization (i.e. bacteria, algae, organic matter) by larvae. Results: Laboratory experiments revealed larval δ§ssup§13§esup§C and δ§ssup§ 15§esup§N composition to reflect the food sources they were reared on. Resource partitioning was demonstrated between An. gambiae and Culex quinquefasciatus larvae sharing the same microcosms. Differences in larval δ§ssup§13§esup§C and δ§ssup§15§ esup§N content was also evident in natural habitats, and Anopheles species were consistently more enriched in δ§ssup§13§esup§C when compared to culicine larvae. Conclusions: These observations demonstrate inter-specific resource partitioning between Cx. quinquefasciatus and An. gambiae larvae in natural habitats in western Kenya. This information may be translated into opportunities for targeted larval control efforts by limiting specific larval food resources, or through bio-control utilizing competitors at the same trophic level. © 2013 Gilbreath et al.; licensee BioMed Central Ltd.


Himeidan Y.E.,Kassala University | Kweka E.J.,Tropical Pesticides Research Institute
Frontiers in Physiology | Year: 2012

East African highlands are one of the most populated regions in Africa. The population densities in the highlands ranged between 158 persons/km 2 in Ethiopia and 410 persons/km 2 in Rwanda. According to the United Nations Population Fund, the region has the world's highest population growth rate. These factors are likely behind the high rates of poverty among the populations. As there were no employment opportunities other than agricultural, this demographic pressure of poor populations have included in an extensive unprecedented land use and land cover changes such as modification of bushland, woodland, and grassland on hillsides to farmland and transformation of papyrus swamps in valley bottoms to dairy pastures and cropland and changing of fallows on hillsides from short or seasonal to longer or perennial. Areas harvested for food crops were therefore increased by more than 100% in most of the highlands. The lost of forest areas, mainly due to subsistence agriculture, between 1990 and 2010 ranged between 8000 ha in Rwanda and 2,838,000 ha in Ethiopia. These unmitigated environmental changes in the highlands led to rise temperature and optimizing the spread and survival of malaria vectors and development of malaria parasites. Malaria in highlands was initially governed by low ambient temperature, trend of malaria transmission was therefore increased and several epidemics were observed in late 1980s and early 2000s. Although, malaria is decreasing through intensified interventions since mid 2000s onwards, these environmental changes might expose population in the highlands of east Africa to an increase risk of malaria and its epidemic particularly if the current interventions are not sustained. © 2012 Himeidan and Kweka.


Chobu M.,University of Dar es Salaam | Nkwengulila G.,University of Dar es Salaam | Mahande A.M.,Tropical Pesticides Research Institute | Mwang'onde B.J.,Tropical Pesticides Research Institute | And 2 more authors.
Acta Tropica | Year: 2015

The increased insecticides resistance by vectors and the ecological harm imposed by insecticides to beneficial organisms drawback mosquitoes chemical control efforts. Biological control would reduce insecticides tolerance and yet biodiversity friend. The predatory and non-predatory effects of Gambusia affinis and Carassius auratus on gravid Anopheles gambiae sensu strict and larvae survivorship were assessed. In determining predation rate, a single starved predator was exposed to third instar larvae of An. gambiae s.s. in different densities 20, 60 and 100. Six replicates in each of the densities for both predators, G. affinis and C. auratus, were set up. The larvae densities were monitored in every12 and 24. h. In assessing indirect effects: An. gambiae s.s. first instar larvae of three densities 20, 60 and 100 were reared in water from a predator habitat and water from non-predator habitat. Larvae were monitored until they emerged to adults where larval survivorship and sex ratio (Female to total emerged mosquitoes) of the emerged adult from both water habitats were determined. Oviposition preference: twenty gravid females of An. gambiae s.s. were provided with three oviposition choices, one containing water from predator habitat without a predator, the second with water from a predator with a predator and the third with water from non-predatory habitat. The number of eggs laid on each container was counted daily. There were 20 replicates for each predator, G. affinis and C. auratus. Survivorship of An. gambiae s.s. larvae reared in water from non-predator habitat was higher than those reared in water from the predator habitats. Many males emerged in water from non-predatory water habitats while more females emerged from predator's habitats water. More eggs laid in tap water than in water from predator habitat and water from predator habitat with live predator. In 24. h, a starved C. auratus and G. affinis were able to consume 100% of the 3rd instar larvae. The findings from this study suggest that G. affinis and C. auratus may be useful in regulating mosquito populations in favour of beneficial insects. However, a small scale trial shall be needed in complex food chain system to ascertain the observed predation and kairomones effects. © 2014 Elsevier B.V.


Felix M.,Tropical Pesticides Research Institute
Renewable and Sustainable Energy Reviews | Year: 2015

Abstract Tanzania is among the lowest income countries with the majority of the people living below a poverty line of less than US$ 2/day. Its energy sector is dominated by wood fuel, mainly charcoal and firewood with over 75% dependency. Wood resources for charcoal and firewood production are collected from a wide variety of tree species. The country has no formal biofuel policies thus leaving biofuel producers (including charcoal and firewood producers) without a reliable framework. This poses a danger to the forest resources and the environment. Little is known about the empirical findings on future prospect and sustainability of charcoal and firewood resources. This study reviewed over 100 articles on the state of the art of wood fuel resources in Tanzania, and the extent and degree of forest resource utilization and sustainability is assessed. Forest loss is estimated at 0.4 million ha per year. Results suggest that it would take about 85 years for all forest resources to be destroyed completely. Assuming year 2005 as a reference year, generations from year 2090 would be left with no forest resources to meet their needs. The study concludes that future prospect and sustainability of charcoal production and firewood harvesting in the country is at stake. Before any irreversible changes occur, it is therefore necessary to protecting forest resources using proper management strategies such as the use of alternative fuel resources, improved conversion technologies and deployment of participatory forest management. © 2015 Elsevier Ltd.


Felix M.,Tropical Pesticides Research Institute
International Journal of Life Cycle Assessment | Year: 2016

Purpose: Life cycle assessment (LCA) has become a standard for assessing what impacts do products and/or services have throughout their entire life cycle. Since the inception of LCA technique, studies have been conducted in different parts of the world, including Tanzania. This study describes the current status of LCA, capacities, and networking in Tanzania. The study has identified what has already been done and potential research gaps that could be explored in future LCA studies. Methods: A state-of-the-art review was conducted on published articles, reports, and other materials on LCA in Tanzania (covering a time frame of 1990–2015) which were searched on databases of scientific research and the general internet using a combination of keywords: “life cycle assessment and Tanzania,” “LCA and Tanzania,” and “life cycle assessment and LCA and Tanzania.” Reviews were on current status, research gaps, and the need for future research. Information related to education or training activities and networking were also gathered and reviewed. Results and discussion: Literature review has revealed that in Tanzania the first LCA study was published in 2007. Few articles and reports were identified in which LCA technique was used mainly for academic research in agriculture, electricity generation, charcoal, biodiesel production from jatropha oil, bioethanol production from sugarcane molasses, production of biofuels from pyrolysis of wood, and production of charcoal from sawmill residues. The very small number of LCA studies conducted in the country could be due to the lack of skilled personnel, lack of local data, and lack of research funds. Tanzania Life Cycle Assessment Network was created to link LCA practitioners and to promote and support further development of LCA in the country. Also, LCA potential is huge yet to be fully explored. Conclusions: This state-of-the-art review is the first of its kind that summarizes and puts together all LCA studies in Tanzania. Most studies faced the challenge of lack of local data, which resulted to the use of secondary data from the literature. In LCA, the use of data from different geographical conditions could cause bias of the results and consequently could affect the decision made or to be made from the study. In this regard, the study recommends the establishment of national LCI database to solve this problem. Also, most studies covered only few impact categories prompting for full LCA studies in future studies. The study also found that there is a need to establish regular LCA training and courses for capacity development. © 2016 Springer-Verlag Berlin Heidelberg


Kweka E.J.,Tropical Pesticides Research Institute | Mwang'Onde B.J.,Tropical Pesticides Research Institute | Mahande A.M.,Tropical Pesticides Research Institute
Parasites and Vectors | Year: 2010

Background. Odour baited resting boxes are simple, reliable and important tools for sampling malaria vector mosquitoes in surveillance and control programmes in different parts of Africa. To optimize the use of cow urine baited resting boxes for sampling An. arabiensis, a community-based study was conducted in Mabogini hamlet in the Lower Moshi irrigation scheme area. Method. Experimental designs using 3 by 3 Latin square were conducted for twenty days to evaluate the following: i) the effect of different parameters in the sampling of mosquitoes using odour baited resting boxes; ii) the performance of odour baited traps under indoor and outdoor conditions and the effect of people sleeping indoors on mosquito density; iii) the effect of position in the placement of traps on collection of mosquitoes; and, iv) the efficiency of the trap outdoors at three different distances from the house wall. One extra house served as the sentinel house to monitor species abundance using a CDC-miniature light trap. Results. 8581 mosquitoes were sampled by odour baited resting boxes of which, 8051 (93.82%) were An. arabiensis and 530 (6.18%) Cx. quinquefasciatus. The light trap collected 12,420 mosquitoes, of which 9442 (76.02%) were An. arabiensis, 126 (1.01%) An. funestus group, 230 (1.85%) An. rufipes and 2622 (21.11%) Cx. quinquefasciatus. The best height for outdoor mosquitoes sampling was 15 cm and 220 cm while indoors was 105 cm. The difference in mosquito collection between different outdoor and indoor heights was statistically significant (p < 0.0001). The optimal outdoor location of odour baited resting boxes from the wall of the house was 3 m. Conclusions. The results of these studies demonstrate an optimal method for sampling during surveillance and control programmes in rural villages of highlands and arid areas of Africa using inexpensive baits and boxes. © 2010 Kweka et al; licensee BioMed Central Ltd.


Kweka E.J.,Tropical Pesticides Research Institute | Kweka E.J.,P.A. College | Nyindo M.,P.A. College | Mosha F.,P.A. College | Silva A.G.,Centro Universitario Vila Velha Uvv Rua Comissario Jose
Parasites and Vectors | Year: 2011

Background: Alternative insecticides for the control of malaria and filarial vectors are of paramount need as resistance is increasing among classes of insecticides currently in use in the public health sector. In this study, mosquitocidal activity of Schinus terebinthifolia essential oil against Anopheles gambiae s.s., An. arabiensis and Culex quinquefasciatus was assessed in laboratory, semi- field and full- field conditions. Method. Twenty third instar larvae of both Anopheles gambiae s.s. and Cx. quinquefasciatus were exposed to different dosages of plant extract in both laboratory and semi- field environments. Observation of the mortality response was assessed at intervals of 12, 24, 48 and 72 hours. Adult semi- gravid female mosquitoes were exposed to papers treated with S. terebinthifolia and compared with WHO standard paper treated with alphacypermethrin (0.05%). Results: Gas chromatography, coupled to mass spectrometry, identified 15 compounds from S. terebinthifolia extracts, the most abundant identified compound was -3-carene (55.36%) and the least was -elemene (0.41%). The density of the oil was found to be 0.8086 g/ml. The effective dosages in the insectary ranged from 202.15 to 2625.20 ppm and were further evaluated in the semi- field situation. In the laboratory, the mortality of Cx. quinquefasciatus ranged from 0.5 to 96.75% while for An. gambiae s.s it was from 13.75 to 97.91%. In the semi- field experiments, the mortality rates observed varied for both species with time and concentrations. The LC 50and LC95value in the laboratory was similar for both species while in the semi- field they were different for each. In wild, adult mosquitoes, the KT50for S. terebinthifolia was 11.29 minutes while for alphacypermethrin was 19.34 minutes. The 24 hour mortality was found to be 100.0% for S. terebinthifolia and 75.0% for alphacypermethrin which was statistically significant (P < 0.001). Conclusion: The efficacy shown by essential oils of fruits and seeds of S. terebinthifolia has given an opportunity for further investigation of individual components of these plant extracts and to evaluate them in small- scale field trials. © 2011 Kweka et al; licensee BioMed Central Ltd.


Kweka E.J.,Tropical Pesticides Research Institute | Senthilkumar A.,Annamalai University | Venkatesalu V.,Annamalai University
Parasites and Vectors | Year: 2012

Background: Essential oils are currently studied for the control of different disease vectors, because of their efficacy on targeted organisms. In the present investigation, the larvicidal potential of essential oil extracted from Indian borage (Plectranthus amboinicus) was studied against the African anthropophagic malaria vector mosquito, Anopheles gambiae. The larvae of An. gambiae s.s laboratory colony and An. gambiae s.l of wild populations were assayed and the larval mortality was observed at 12, 24 and 48 h after exposure period with the concentrations of 3.125, 6.25, 12.5, 25, 50 and 100 ppm. Findings. Larval mortality rates of the essential oil was entirely time and dose dependent. The LC50 values of the laboratory colony were 98.56 (after 12h) 55.20 (after 24 h) and 32.41 ppm (after 48 h) and the LC 90 values were 147.40 (after 12h), 99.09 (after 24 h) and 98.84 ppm (after 48 h). The LC50 and LC90 values of the wild population were 119.52, 179.85 (after 12h) 67.53, 107.60 (after 24 h) and 25.51, 111.17 ppm (after 48 h) respectively. The oil showed good larvicidal potential after 48 h of exposure period against An. gambiae. The essential oil of Indian borage is a renowned natural source of larvicides for the control of the African malaria vector mosquito, An. gambiae. Conclusion: The larvicidal efficacy shown by plant extracts against An. gambiae should be tested in semi field and small scale trials for effective compounds to supplement the existing larval control tools. © 2012 Kweka et al.; licensee BioMed Central Ltd.

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