Department of Biociences

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Influence of mangrove deforestation on nutrition ecology and genetic diversity of uca annulipes along the Tanzania mainland and Zanzibar coast
(Vrije University Brussel, 2000) Alex, Nehemia; Dehairs, Frank; Marc, Kochzius
Management and utilisation of miombo biodiversity: impact of refugees influx in kasulu, Tanzania
(International Master Programme at the Swedish Biodiversity Centre, 2003) Andrew, Woiso Dino
his study was conducted in Kasulu district in Western Tanzania to assess the impact of refugees influx on the management and utilisation of miombo woodland biodiversity. Specifically, the objectives were to (a) assess the uses of and means of using forest resources by refugees and local Tanzanians, (b) compare the extent of impact resulting from harvesting woodland resources between refugees and local inhabitants and to recommend on how the means of utilisation affect sustainability issues of the forest resources. Questionnaire surveys, participant observation and forest inventories were used as tools for data collection. A total of two hundred and forty people were interviewed from two villages and two refugee camps using a pre-tested questionnaire form for the aim of getting baseline data. From each village and camp a nearby forest, which is currently a harvesting site for various Timber and Non-Timber Forest Products (NTFPs) by local Tanzanians or refugees, was used for the inventory. In addition a forest reserve was inventoried as a control site for the other forest areas surveyed. Commonly used tree species were counted and measured for Diameter at Breast Height (DBH). Other notes were made whenever activities such as charcoaling, chalk making, logging and grazing were observed. It was witnessed during participant observation that a huge area of formally miombo woodland and mostly village forest reserves had been converted to settlements and farmlands for refugees. It was found that refugees’ harvesting sites have fewer trees/ha and smaller diameter trees compared to villagers’ forests. The reserve, village and camp forests surveyed had 738, 474 & 351stems/ha. The village forests had a higher species diversity than the other forests at 95% CI (p=0.0008). Pterocarpus angolensis, which is a valuable timber species, was found almost locally depleted with exception of few juveniles found in the village forests. It was deduced from these findings that miombo woodlands in this area are experiencing rapid deforestation due to faster rate of utilisation, hence highlighting possibilities for degrading its biodiversity. Management of these forests, which locally doesn’t have any specific interventional plans and strategies, is facing challenges. The extent of these challenges become complicated since the time for refugees repatriation is not known with certainty. There is a need to assess and redefine present ownership and management patterns and strategies as one of ways to cope with current use pressure and rehabilitate the miombo woodlands in this area. Further studies to compare this influence of massive harvest of miombo resources with places practicing subsistence harvesting of miombo resources are recommended. It is also recommended to carryout population studies for Pterocarus angolensis in Kigoma region to come up with more detailed information about its status for it is highly demanded for furniture despite its threatened status.
Therapeutic efficacy of sulfadoxine-pyrimethamine and prevalence of resistance markers in Tanzania prior to revision of malaria treatment policy: Plasmodium falciparum dihydrofolate reductase and dihydropteroate synthase mutations in monitoring in vivo resistance
(The American Society of Tropical Medicine and Hygiene, 2004) Mugittu, Kefas; Ndejembi, Modesta; Malisa, Allen; Lemnge, Martha; Premji, Zulfikar; Mwita, Alex; Nkya, Watoky; Kataraihya, Johannes; Abdulla, Salim; Beck, Hans-Peter; Mshinda, Hassan
Prior to the 2001 malarial treatment policy change in Tanzania, we conducted trials to assess the efficacy of sulfadoxine-pyrimethamine (SP) and the usefulness of molecular markers in monitoring resistance. A total of 383 uncomplicated Plasmodium falciparum malaria patients (between 6 and 59 months old) were treated with SP and their responses were assessed. Mutations in the P. falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) genes in admission day blood samples were analyzed. Results indicated that 85.6% of the patients showed an adequate clinical response, 9.7% an early treatment failure, and 4.7% a late treatment failure. The quintuple mutant genotype (pfdhfr 51 Ile, 59 Arg, and 108 Asn and pfdhps 437 Gly and 540 Glu) showed an association with treatment outcome (odds ratio 2.1; 95% confidence interval 0.94–4.48, P 0.045). The prevalence of the triple pfdhfr mutant genotype (51 Ile, 59 Arg, and 108 Asn) at a site of high SP resistance (23.6%) was four times higher compared with that observed at sites of moderate SP resistance (6.8−14.4%) (P 0.000001). The genotype failure index calculated by using this marker was invariable (1.96−2.1) at sites with moderate SP resistance, but varied (3.4) at a site of high SP resistance. In conclusion, our clinical and molecular findings suggest that SP may have a short useful therapeutic life in Tanzania; thus, its adoption as an interim first-line antimalarial drug. The findings also point to the potential of the triple pfdhfr mutant genotype as an early warning tool for increasing SP resistance. These data form the baseline SP efficacy and molecular markers profile in Tanzania prior to the policy change.
Reduced variatio around drug-resistant dhfr alleles in African plasmodium falciparum
(Oxford University Press, 2005-05-25) Pearce, Richard J; Malisa, Allen L; Kachur, Patrick; Barnes, Karen; Brian, Sharp; Roper, Cally
We have measured microsatellite diversity at 26 markers around the dhfr gene in pyrimethamine-sensitive and -resistant parasites collected in southeast Africa. Through direct comparison with diversity on sensitive chromosomes we have found significant loss of diversity across a region of 70 kb around the most highly resistant allele which is evidence of a selective sweep attributable to selection through widespread use of pyrimethamine (in combination with sulfadoxine) as treatment for malaria. Retrospective analysis through four years of direct and continuous selection from use of sulfadoxinepyrimethamine as first-line malaria treatment on a Plasmodium falciparum population in KwaZulu Natal, South Africa, has revealed how recombination significantly narrowed the margins of the selective sweep over time. A deterministic model incorporating selection coefficients measured during the same interval indicates that the transition was toward a state of recombination-selection equilibrium. We compared loss of diversity around the same resistance allele in two populations at either extreme of the range of entomological inoculation rates (EIRs), namely, under one infective bite per year in Mpumalanga, South Africa, and more than one per day in southern Tanzania. EIRs determine effective recombination rates and are expected to profoundly influence the dimensions of the selective sweep. Surprisingly, the dimensions were broadly consistent across both populations. We conclude that despite different recombination rates and contrasting drug selection histories in neighboring countries, the region-wide movement of resistant parasites has played a key role in the establishment of resistance in these populations and the dimensions of the selective sweep are dominated by the influence of high initial starting frequencies.
Dhfr and dhps mutations in plasmodium falciparum isolates in Mlandizi, Kibaha, Tanzania: association with clinical outcome
(Tanzania Health Research Bulletin, 2006-05) Kidima, W; Nkwengulila, G.; Premji, Z.; Malisa, A.; Mshinda, H
Sulfadoxine-pyrimethamine (SP), the current first line antimalarial drug in Tanzania, is compromised by evolution and spread of mutations in the parasite's dhfr and dhps genes. In the present study we established the baseline frequencies of Plasmodium falciparum dihydrofolate reductase (pfdhfr) and dihydropteroate synthase (pfdhps) mutant genotypes and their potential for predicting the in vivo efficacy of SP in Mlandizi, Tanzania. The efficacy of SP treatment was by following 116 children with uncomplicated falciparum malaria for 14 days after treatment. Infected blood samples were collected on filter paper at days 0, 3, 7 and 14. Parasite genomic DNA was extracted and point mutations at positions 51, 59, 108 and 164 of the dhfr gene and at 581, 540 and 437 of the dhps gene were analysed by nested Polymerase Chain Reaction/ Restriction Fragment Length Polymorphism. Out of 116 children enrolled, 98 (86%) of eligible children demonstrated an adequate clinical response by day 14. There were 7.3 % early and 6.7% late therapeutic failures. At day 0, only 8.0% (4/50) the parasites showed no mutation at the dhfr locus; for dhps this was 73%. Triple mutant dhfr alleles (Ile 51, Arg 59, Asn 108) occurred in 47%, double mutant dhps (Gly 437, Glu 540) alleles in 7.9%. No mutation was detected at codon 164 of the dhfr gene. The presence of triple dhfr mutant alleles was related to clinical failure, but did not show significant association (Fisher exact test, P=0.166, OR 2.15 0.776.20). The higher rates of mutation on the dhfr do not spell a bright future for SP treatment in Tanzania. It is rational to think of an alternative first line antimalarial drug, while retaining SP for malaria intermittent treatment in pregnancy.
The potential of mitochondrial DNA markers and polymerase chain reaction-restriction fragment length polymorphism for domestic and wild species identification
(Sokoine University of Agriculture, Tanzania., 2006-09-18) Malisa, A.L.; Gwakisa, P; Balthazary, S.; Wasser, S. K; Mutayoba, B. M.
Poaching is increasingly presenting challenge to conservational authorities in Africa. Accurate and reliable methods for the identification of poached wildlife meat when morphological features are missing, has been lacking in Africa. We describe a molecular based approach that has a potential of serving as a tool for game and domestic meat identification in Africa. A mitochondrial (mt246) marker and Rsa1 restriction enzyme were used in the PCR-RFLP species identification of game and domestic meat. Species-specific reference DNA fragment patterns were obtained using fresh meat from ten major wild herbivores, representing the highly targeted wild meat species in Tanzania and four domesticated animal species. With the exception of the zebra, all species produced unique monomorphic RFLP patterns that were species specific. These reference fragment patterns enabled identification of about 75% of unknown meat samples, demonstrating the ability of the technique in discriminating between and among wild and domestic species. The results provide preliminary promising fingerprints which need further validation for future use for the control of the up-surging bush meat trade in the continent.
Drug resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum malaria in Mlimba, Tanzania
(Malaria Journal, 2006-10) Mbugi, Erasto V; Mutayoba, Benezeth M; Malisa, Allen L; Balthazary, Sakurani T; Nyambo, Thomas B; Mshinda, Hassan
Background: Sulphadoxine-pyrimethamine (SP) has been and is currently used for treatment of uncomplicated Plasmodium falciparum malaria in many African countries. Nevertheless, the response of parasites to SP treatment has shown significant variation between individuals. Methods: The genes for dihydrofolate reductase (dhfr) and dihydropteroate synthase (dhps) were used as markers, to investigate parasite resistance to SP in 141 children aged less than 5 years. Parasite DNA was extracted by Chelex method from blood samples collected and preserved on filter papers. Subsequently, polymerase chain reaction (PCR) and restriction fragment length polymorphism (PCR-RFLP) were applied to detect the SP resistance-associated point mutations on dhfr and dhps. Commonly reported point mutations at codons 51, 59, 108 and 164 in the dhfr and codons 437, 540 and 581 in the dhps domains were examined. Results: Children infected with parasites harbouring a range of single to quintuple dhfr/dhps mutations were erratically cured with SP. However, the quintuple dhfr/dhps mutant genotypes were mostly associated with treatment failures. High proportion of SP resistance-associated point mutations was detected in this study but the adequate clinical response (89.4%) observed clinically at day 14 of follow up reflects the role of semi-immunity protection and parasite clearance in the population. Conclusion: In monitoring drug resistance to SP, concurrent studies on possible confounding factors pertaining to development of resistance in falciparum malaria should be considered. The SP resistance potential detected in this study, cautions on its useful therapeutic life as an interim firstline drug against malaria in Tanzania and other malaria-endemic countries.
The potentials of traditional African cultural practices in mitigating overexploitation of wildlife species and habitat loss: experience of Tanzania
(Taylor Francis, 2009-01) Kideghesho, Jafari R
Both colonial and post-colonial conservation policies ignored the potential role of traditional African cultural practices in contributing to conservation goals. Recently, there has been a growing global interest in these practices, although recognition in official conservation policies is still minimal in many countries. This global interest is enthused by the reality that although the use of wild species and their habitats remains the foundation for human survival all over the world, there is a huge risk of losing these species. Factors such as rapid human population increase, inadequate local support for conservation policies, limited strategies for survival among local communities and inadequate capacity of the government to fund law enforcement operations against illegal activities subject the species and habitats to unsustainable use. Traditional cultural practices, among other strategies, have promising potential to enhance sustainable resource use and conservation and, therefore, realize the desire for ecological and social sustainability. Using examples and data drawn from different parts of Tanzania, this paper attempts to uncover some of these potentials on which policy-makers and conservationists can capitalize to augment conservation work. The paper begins by reviewing the ecological impacts of two major conservation problems facing Tanzania – species overexploitation and habitat loss. Then the possible advantages of traditional cultural practices (compared to conventional conservation strategies) are outlined. The traditional practices are presented as more cost-effective, more socially acceptable and having minimal risk of failure. Furthermore, the idea of reviving these practices coincides with the philosophy of co-management approaches, which advocate sharing of power, rights and responsibilities between the state and local resource users. This is based on the idea that local communities constitute voices ‘from the ground’ that should be heard. In showing the efficacy of traditional African cultural practices, the paper specifically focuses on four elements: traditional institutions, taboos, sacred sites and totemic species.
Knowledge and practices on malaria and its control among pastoralists in Simanjiro District, northern Tanzania
(Sokoine University of Agriculture, Tanzania., 2009-10-04) Malisa, A.L.; Ndukai, M.
Community knowledge and practice related to malaria is important for the implementation of appropriate, effective and sustainable interventions. This study was carried out to assess knowledge and practices on malaria and identify factors contributing to the low mosquito net coverage in Simanjiro District in northern Tanzania. A combination of direct observation, focus group discussion (FGD) and questionnaire were employed in data collection. A sample of 200 respondents was selected randomly from 5542 people from the study village. The findings show that, although most (75%) of the respondents were informed that mosquitoes transmit malaria, the remaining quarter of respondents reserved a considerable doubt on the link between mosquitoes and malaria. Sixty five percent of the respondents were aware of the use of insecticide treated nets (ITNs). However, the coverage of any mosquito net and ITN was 12.5% and 5%, respectively. Affordability, unavailability and gender inequality were identified to be major factors associated with the low ITN coverage. The study recommends that, an advocated pluralistic approach of ITN delivery which encourages a coordinated public private alliance is required to ensure equitable and large scale distribution of ITNs in the village.
Potentials of and threats to traditional institutions for community based biodiversity management in dryland areas of lower Moshi, Tanzania
(Journal of Forest Science, 2009-12) Woiso, Dino Andrew; Shemdoe, Riziki Silas; Kayeye, Heri
Dryland species and ecosystems have developed unique strategies to cope with low and sporadic rainfall. They are highly resilient and recover quickly from prevailing disturbances such as fires, herbivore pressure and drought. Dryland people have engineered pastoral and farming systems, which are adapted to these conditions and have sustained the livelihoods of dryland people for centuries. In this article, we present the status of potentials and threats to dryland biodiversity and explore options for its conservation and sustainable use. Findings of the research can be summarized as follows: (i) The ecosystem goods and services are highly valued by the community but mechanism for wise use of the resources has disappeared, (ii) forests are under the ownership of the government but the local community is the realistic custodian of the forests through village leaderships and environmental committees; (iii) the immediate major threat to dryland biodiversity held in the forests appears to be the degradation of ecosystems and habitats caused by new and powerful forces of environmental degradation such as large scale irrigation of rice farms, poverty-induced overexploitation of natural resources, and disappearance and ignorance of traditional institutions for management of dryland biodiversity. These new forms of disturbances often overpower the legendary resilience of dryland ecosystems and constitute potentially serious threats to dryland biodiversity. Forests, wetlands and oases all of which are micro hot spots of dryland biodiversity, appear to be particularly vulnerable hence the need to set up some rules and regulations for sustainable utilization of these resources.
Drug coverage in treatment of malaria and the consequences for resistance evolution – evidence from the use of sulphadoxine/ pyrimethamine
(Malaria Journal, 2010) Malisa, Allen L.; Pearce, Richard J.; Abdulla, Salim; Mshinda, Hassan; Kachur, Patrick S.; Bloland, Peter; Roper, Cally
Background: It is argued that, the efficacy of anti-malarials could be prolonged through policy-mediated reductions in drug pressure, but gathering evidence of the relationship between policy, treatment practice, drug pressure and the evolution of resistance in the field is challenging. Mathematical models indicate that drug coverage is the primary determinant of drug pressure and the driving force behind the evolution of drug resistance. These models show that where the basis of resistance is multigenic, the effects of selection can be moderated by high recombination rates, which disrupt the associations between co-selected resistance genes. Methods: To test these predictions, dhfr and dhps frequency changes were measured during 2000-2001 while SP was the second-line treatment and contrasted these with changes during 2001-2002 when SP was used for first-line therapy. Annual cross sectional community surveys carried out before, during and after the policy switch in 2001 were used to collect samples. Genetic analysis of SP resistance genes was carried out on 4,950 Plasmodium falciparum infections and the selection pressure under the two policies compared. Results: The influence of policy on the parasite reservoir was profound. The frequency of dhfr and dhps resistance alleles did not change significantly while SP was the recommended second-line treatment, but highly significant changes occurred during the subsequent year after the switch to first line SP. The frequency of the triple mutant dhfr (N5 ,C59R,S108N) allele (conferring pyrimethamine resistance) increased by 37% - 63% and the frequency of the double A437G, K540E mutant dhps allele (conferring sulphadoxine resistance) increased 200%-300%. A strong association between these unlinked alleles also emerged, confirming that they are co-selected by SP. Conclusion: The national policy change brought about a shift in treatment practice and the resulting increase in coverage had a substantial impact on drug pressure. The selection applied by first-line use is strong enough to overcome recombination pressure and create significant linkage disequilibrium between the unlinked genetic determinants of pyrimethamine and sulphadoxine resistance, showing that recombination is no barrier to the emergence of resistance to combination treatments when they are used as the first-line malaria therapy.
Media, health workers, and policy makers’ relationship and their impact on antimalarial policy adoption: a population genetics perspective
(Sokoine University of Agriculture, Tanzania., 2010-04) Malisa, Allen L; Pearce, Richard J; Mutayoba, Benezeth; Abdullah, Salim; Mshinda, Hassan; Kachur, Patrick; Bloland, Peter; Roper, Cally
Drug resistance negatively impacts malaria treatments, making treatment policy revision unavoidable. So far, studies relating sociopolitical and technical issues on policy change with malaria parasite genetic change are lacking.We have quantified the effect of malaria treatment policy on drug pressure and the influence of the media, policy makers, and health worker relationship on parasite population genetic change in Kilombro/Ulanga district. Cross-sectional surveys of asymptomatic infections conducted before, during and after the switch from chloroquine to sulphadoxine/pyrimethamine were used for genetic analysis of SP resistance genes in 4,513 asymptomatic infections identified, and their frequency change was compared with retrospective study of the documented process of policy change. Highly significant changes of dhfr and dhps resistance alleles occurred within one year of switch to SP first line, followed by a decline of their rate of selection caused by reduction of SP usage, as a result of negative media reports on SP usage and lack of adequate preparations.
Prevalence and constraints of typhoid fever and its control in an endemic area of Singida region in Tanzania: Lessons for effective control of the disease
(Journal of Public Health and Epidemiology, 2010-08) Malisa, Allen L; Nyaki, Honest
Typhoid fever (TF) is an important communicable disease that is endemic to Tanzania, quite often complicated with malaria co-infection leading to diagnostic complications and significant mortality. Despite considerable control efforts, the disease continues to persist in Singida urban leading to significant morbidity and mortality. This paper retrospectively examines morbidity and mortality trend of typhoid infection for the past five years in Singida urban. By using questionnaire, Focus Group Discussion (FGD) and direct observational methods, the authors report interview results of 120 respondents from the study community, regarding their awareness of TF and its control methods. Results showed that, the TF prevalence records revealed a fluctuating trend with annual incidence rate of 580 – 1,400/100,000 persons, and an overall increase from 771 – 942 cases/100,000 persons (p _ 0.0001) between 2003 and 2007. While 88% of the respondents were aware of TF disease, 53% were unaware of its control methods. The study also revealed an acute shortage of diagnostic laboratory services which indicated that, 75% of health facilities had no such services. In adequate knowledge about personal hygiene, scarcity or lack of access to safe water, improper drainage systems and problems of unsanitary toilets in Singida urban were some of the obstacles to effective TF control. Effective TF control measures in the study district, as in other areas in the tropics, requires integration of intensive health education as a public health tool, provision and access to safe water supply and adequate strengthening of health systems.
The genetic change in P. falciparum populations of rural Tanzania resulting from national policy on firstline malaria treatment and pilot Sulfadoxine/pyrimethamine and Artesunate combination
(Malaria Journal, 2010-10) Malisa, Allen L; Pearce, Richard J; Abdullah, Salim; Mshinda, Hassan; Kachur, Patrick; Bloland, Peter; Roper, Cally
Theory predicts that we can protect the efficacy of future antimalarials by changing treatment practice or drug formulation, but the potential success of such interventions rests upon their impact on drug pressure in the field. So far, gathering field data on the relationship between policy, drug pressure, recombination and the evolution of resistance has been entirely challenging. To test these predictions, dhfr and dhps frequency changes were measured in two rural districts of Rufiji and Kilombero/Ulanga during 2000-2006, and the frequencies of the two genes compared prior, during and after antimalarial policy change from first line CQ to first line SP in 2001. Furthermore, while SP first line was maintained in Kilombero/Ulanga, pilot combination therapy of SP+Artesunate (ART) was introduced in Rufiji in 2002 to replace SP and dhfr and dhps frequency changes compared between the two districts. Size polymorphisms at three sets of microsatellite loci linked to dhfr and three other sets of unlinked microsatellite loci were analysed. Genetic analysis of SP resistance genes was carried out on 9,662 Plasmodium falciparum infections identified in a series of annual cross sectional surveys conducted in the two districts between 2000-2006. The frequency of dhfr and dhps resistance alleles did not change significantly while SP was the recommended second-line treatment, but highly significant changes occurred during the subsequent year after the switch to first line SP. The frequency of the triple mutant dhfr allele increased by 37% -63% and that of double mutant dhps allele increased 200%-300%. A strong association between these unlinked alleles also emerged; confirming that they are co-selected by SP. Distribution of major lineages indicates that there is extensive genetic exchange among the geographic regions. Combination therapy had visible effect on the frequencies of dhfr and dhps resistance alleles. The findings of this study provide insight on the interplay between policy, drug pressure, recombination and the evolution of resistance.
Molecular monitoring of resistant dhfr and dhps allelic haplotypes in Morogoro and Mvomero districts in south eastern Tanzania
(African Health Sciences, 2011) Malisa, Allen L.; Pearce, R.; Abdullah, S.; Mutayoba, B.; Mshinda, H.; Kachur, P.; Bloland, P.; Roper, C.
Background: Resistance to the antimalarial drug sulfadoxine-pyrimethamine (SP) emerged in Plasmodium falciparum from Asia in the 1960s and subsequently spread to Africa. In Tanzania, SP use as a national policy began in 1983 as a second line to chloroquine (CQ) for the treatment of uncomplicated malaria, until August 2001 when it was approved to replace CQ as a national first line. Objective: The present study assesses the frequency of resistant dhfr and dhps alleles in Morogoro-Mvomero district in south eastern Tanzania and contrast their rate of change during 17 years of SP second line use against five years of SP first line use. Methodology: Cross sectional surveys of asymptomatic infections were carried out at the end of rainy season during July- September of 2000, when SP was the national second line (CQ was the first line) and 2006 when SP was the national first line antimalarial treatment. Genetic analysis of SP resistance genes was carried out on 1,044 asymptomatic infections and the effect of the two policies on SP evolution compared. Results: The frequency of the most resistant allele, the double dhps-triple dhfr mutant genotype, increased by only 1% during 17 years of SP second line use, but there was a dramatic increase by 45% during five years of SP first line use. Conclusion: We conclude that National policy change from second line to first line SP, brought about an immediate shift in treatment practice and this in turn had a highly significant impact on drug pressure. The use of SP in specific programs only such as intermittent preventive treatment of infants (IPTi) and intermittent preventive treatment of pregnant women (IPTp) will most likely reduce substantially SP selection pressure and the SP resistance alleles alike.
The evolution of pyrimethamine resistant dhfr in Plasmodium falciparum of south-eastern Tanzania: comparing selection under SP alone vs SP +artesunate combination
(Malaria Journal, 2011) Malisa, Allen L; Pearce, Richard J; Mutayoba, Ben M; Abdullah, Salim; Mshinda, Hassan; Kachur, Patrick S; Bloland, Peter; Roper, Cally
Background: Sulphadoxine-pyrimethamine (SP) resistance is now widespread throughout east and southern Africa and artemisinin compounds in combination with synthetic drugs (ACT) are recommended as replacement treatments by the World Health Organization (WHO). As well as high cure rates, ACT has been shown to slow the development of resistance to the partner drug in areas of low to moderate transmission. This study looked for evidence of protection of the partner drug in a high transmission African context. The evaluation was part of large combination therapy pilot implementation programme in Tanzania, the Interdisciplinary Monitoring Programme for Antimalarial Combination Therapy (IMPACT-TZ) Methods: The growth of resistant dhfr in a parasite population where SP Monotherapy was the first-line treatment was measured for four years (2002-2006), and compared with the development of resistant dhfr in a neighbouring population where SP + artesunate (SP+AS) was used as the first-line treatment during the same interval. The effect of the differing treatment regimes on the emergence of resistance was addressed in three ways. First, by looking at the rate of increase in frequency of pre-existing mutant dhfr alleles under monotherapy and combination therapy. Second, by examining whether de-novo mutant alleles emerged under either treatment. Finally, by measuring diversity at three dhfr flanking microsatellite loci upstream of the dhfr gene Results: The reduction in SP selection pressure resulting from the adoption of ACT slowed the rate of increase in the frequency of the triple mutant resistant dhfr allele. Comparing between the two populations, the higher levels of genetic diversity in sequence flanking the dhfr triple mutant allele in the population where the ACT regimen had been used indicates the reduction in SP selection pressure arising from combination therapy. Conclusion: The study demonstrated that, alleles containing two mutations at the dhfr have arisen at least four times independently while those containing triple mutant dhfr arose only once, and were found carrying a single unique Asian-type flanking sequence, which apparently drives the spread of pyrimethamine resistance associated dhfr alleles in east Africa. SP+AS is not recommended for use in areas where SP cure rates are less than 80% but this study reports an observed principle of combination protection from an area where pyrimethamine resistance was already high.
Low sensitivity of paraHIT-f rapid malaria test among patients with fever in rural health centers, Northern Tanzania
(J Infect Dev Ctries, 2011) Kweka, Eliningaya J.; Lowassa, Asanterabi; Msangi, Shandala; Kimaro, Epiphania E.; Lyatuu, Ester E.; Mwang’onde, Beda J.; Mahande, Aneth M.; Mazigo, Humphrey D.
Introduction: Several rapid diagnostic tools for malaria are currently available in local markets. However, diagnostic accuracy varies widely. The present study was conducted to evaluate a cheaply and easily available rapid diagnostic malaria test (ParaHIT-f) in rural Tanzania. Methodology: Participants presenting with fever at health centers in the Kilimanjaro and Manyara regions were eligible. Parasitological thin and thick smears were examined from finger-prick blood samples and compared to ParaHIT-f test results. Sensitivity, specificity and predictive values were calculated using microscopic parasitological examination as the gold standard. Results: In total, 236/743 (31.8%) individuals had a positive malaria microscopy, and 25/715 (3.4%) were positive in the rapid diagnostic test. The sensitivity of ParaHIT-f was 10.7% (95% CI, 6.7-14.7) and specificity was 100% (95% CI, 97.4-102), with positive and negative predictive values (PPV and NPV) of 100% (95% CI, 99.1-100.2) and 70.9% (95% CI, 66.9-74.9) respectively. Sensitivity of ParaHIT-f increased with increasing P. falciparum density (P > 0.003) from 5.8% (95% CI, 0-12.9) at < 100 parasites/μl to 20.5% (95% CI, 13.5-27) at ≥ 100 parasites/μl. Conclusions: Sensitivity of the ParaHIT-f rapid test was very low in this setting, therefore concomitant use of rapid diagnostic tests and microscopy is recommended. In the case of positive test results, confirmation by parasitological techniques is not necessary. Further monitoring of ParaHIT-f in various epidemiological settings in Tanzania is warranted.
Artemisinin combination therapies price disparity between government and private health sectors and its implication on antimalarial drug consumption pattern in Morogoro Urban District, Tanzania
(BMC Research Notes, 2012) Malisa, Allen Lewis; Kiriba, Deodatus
Universal access to effective treatments is a goal of the Roll Back Malaria Partnership. However, despite official commitments and substantial increases in financing, this objective remains elusive, as development assistance continue to be routed largely through government channels, leaving the much needed highly effective treatments inaccessible or unaffordable to those seeking services in the private sector. To quantify the effect of price disparity between the government and private health systems, this study have audited 92 government and private Drug Selling Units (DSUs) in Morogoro urban district in Tanzania to determine the levels, trend and consumption pattern of antimalarial drugs in the two health systems. A combination of observation, interviews and questionnaire administered to the service providers of the randomly selected DSUs were used to collect data. ALU was the most selling antimalarial drug in the government health system at a subsidized price of 300 TShs (0.18 US$). By contrast, ALU that was available in the private sector (coartem) was being sold at a price of about 10,000 TShs (5.9 US$), the price that was by far unaffordable, prompting people to resort to cheap but failed drugs. As a result, metakelfin (the phased out drug) was the most selling drug in the private health system at a price ranging from 500 to 2,000 TShs (0.29–1.18 US$). In order for the prompt diagnosis and treatment with effective drugs intervention to have big impact on malaria in mostly low socioeconomic malaria-endemic areas of Africa, inequities in affordability and access to effective treatment must be eliminated. For this to be ensued, subsidized drugs should be made available in both government and private health sectors to promote a universal access to effective safe and affordable life saving antimalarial drugs.
Length-Weight relationship and condition factor of tilapia species grown in marine and fresh water ponds
(Agriculture and Biology Journal of North America, 2012) Nehemia, Alex; Maganira, Justin D.; Rumisha, Cyrus
The aim of this study was to describe the differences in Length-Weight relationship and condition factor of Tilapia zillii and Oreochromis urolepis urolepis reared in full strength sea water (FSSW) and fresh water (FW) ponds. The environmental condition in FSSW and FW ponds were also analyzed to determine their impacts on Length-Weight relationship and condition factor on both species. The regression coefficient "b" exhibit negative allometric growth in FW and positive allometric growth in FSSW for both species. The value of exponent "b" and condition factor (K) for T. zillii in FW and FSSW (in the bracket) were found to be 2.94 (3.3) and 2.07 (0.74) respectively. On the other hand the value of exponent "b" and condition factor (K) for O. urolepis urolepis in FW and FSSW (in the bracket) were found to be 2.81 (3.46) and 0.86 (0.53) respectively. Though both species performed well in FW, the study also revelead that farming of these tilapia species in FSSW can be feasible if water quality parameters are properly monitored.
Quantification of markers of antimalarial drug resistance from an area of high malaria transmission: Comparing frequency with prevalence
(Academic Journals, 2012-08-28) Malisa, Allen L.; Pearce, Richard J.; Mutayoba, Ben; Abdullah, Salim; Mshinda, Hassan; Kachur, Patrick; Bloland, Peter; Roper, Cally
Molecular monitoring of markers of antimalarial drug resistance offers an affordable alternative to the in vivo method for the detection of resistance, and has the potential to guide public health policy in a timely manner. However, the optimal way of analyzing and reporting these data, particularly those emanating from areas of moderate to high malaria transmission, has never been fully explored or agreed upon, given the potential of being confounded by coinfections. By using large number of real field samples, we quantified the difference between prevalence and frequency when reporting field data on antimalarial drug resistance obtained by direct counting of haplotypes. Polymerase chain reaction (PCR) and sequence specific oligonucleotide probing was used to generate point mutations which were used to construct haplotypes. Results indicate that frequency underestimates haplotypes present at low levels while also amplifying haplotypes present at high levels; prevalence on the other hand behaved in a vice versa manner. Both prevalence and frequency are therefore essential, as each may have relevance in different contexts in high malaria transmission settings. Frequency is essential to gauge the impact of intervention on antimalarial drug resistance while prevalence may be more relevant when the aim is to determine parasite clearance

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