Browsing by Author "Malisa, Allen L"

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Drug resistance to sulphadoxine-pyrimethamine in Plasmodium falciparum malaria in Mlimba, Tanzania
(Malaria Journal) Mbugi, Erasto V; Mutayoba, Benezeth M; Malisa, Allen L; Balthazary, Sakurani T; Nyambo, Thomas B; Mshinda, Hassan
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.
Media, health workers, and policy makers’ relationship and their impact on antimalarial policy adoption: a population genetics perspective
(Sokoine University of Agriculture, Tanzania.) Malisa, Allen L; Pearce, Richard J; Mutayoba, Benezeth; Abdullah, Salim; Mshinda, Hassan; Kachur, Patrick; Bloland, Peter; Roper, Cally
Multiplicity of infections and level of recrudescence in Plasmodium falciparum malaria in Mlimba, Tanzania
(Academic Journals) Mbugi, Erasto V.; Mutayoba, Benezeth M; Balthazary, Sakurani T; Malisa, Allen L; Nyambo, Thomas B; Mshinda, Hassan
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) Malisa, Allen L; Nyaki, Honest
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.
Reduced variatio around drug-resistant dhfr alleles in African plasmodium falciparum
(Oxford University Press) Pearce, Richard J; Malisa, Allen L; Kachur, Patrick; Barnes, Karen; Brian, Sharp; Roper, Cally
Species and gender differentiation between and among domestic and wild animals using mitochondrial and sex-linked DNA markers
Malisa, Allen L; Balthazary, Sakurani; Wasser, Sam; Mutayoba, Benezeth; Gwakisa, Paul
Species and gender differentiation between and among domestic and wild animals using mitochondrial and sex-linked DNA markers
(2005-11) Malisa, Allen L; Balthazary, Sakurani; Wasser, Sam; Mutayoba, Benezeth; Gwakisa, Paul
In many African countries accurate and reliable identification of poached wildlife products like carcasses or meat presents a big problem when morphological characters such as skin hair or bones are missing. We describe a molecular based approach that has a potential of serving as a forensic tool in game meat identification in Africa. A mitochondial DNA marker (mt700) and one restriction enzyme, Rsa1 were used in the PCR-RFLP species identification of game meat obtained from two National Parks in Tanzania. Species-specific reference DNA fragment patterns were obtained using fresh meat from ten wildlife and four domesticated species. All species except the zebra, produced unique monomorphic RFLP patterns. Collectively, these patterns demonstrate the potential ability of genetic techniques for discriminating between and among wildlife and domestic species. The reference PCR-RFLP fragments enabled species identification of about 79% of unknown meat samples. In addition, sex was also assigned to all of the samples following successful amplification of gender-specific, SRY and ZFY/X, chromosomal domains. Although the present study has been conducted on a limited range both in numbers and genetic diversity of wildlife species present in Africa, the results demonstrate the potential usefulness of the DNA approach in wildlife forensics in the continent.
The evolution of pyrimethamine resistant dhfr in Plasmodium falciparum of south-eastern Tanzania: comparing selection under SP alone vs SP +artesunate combination
(Malaria Journal) Malisa, Allen L; Pearce, Richard J; Mutayoba, Ben M; Abdullah, Salim; Mshinda, Hassan; Kachur, Patrick S; Bloland, Peter; Roper, Cally
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) Malisa, Allen L; Pearce, Richard J; Abdullah, Salim; Mshinda, Hassan; Kachur, Patrick; Bloland, Peter; Roper, Cally