Background. Tools that estimate recent and long-term malaria transmission in a population would b... more Background. Tools that estimate recent and long-term malaria transmission in a population would be highly useful for malaria elimination programs. Methods. The prevalence of antibodies to 11 Plasmodium falciparum antigens was assessed by cytometric bead assay or enzyme-linked immunosorbent assay in 1000 people in a highland area of Kenya over 14 months, during a period of interrupted malaria transmission. Results. Antibodies differed by antigen in acquisition with age: rapid (>80% antibody positive by age 20 years, 5 antigens), moderate (>40% positive by age 20 years, 3 antigens), or slow (<40% positive by age 20 years, 3 antigens). Antibody seroreversion rates in the 14 months between samples decreased with age rapidly (7 antigens), slowly (3 antigens), or remained high at all ages (schizont extract). Estimated antibody half-lives in individuals >10 years of age were long (40 to >80 years) for 5 antigens, moderate (5-20 years) for 3 antigens, and short (<1 year) for 3 antigens. Conclusions. Antibodies to P. falciparum antigens in malaria-endemic areas vary by age, antigen, and time since last exposure to P. falciparum. Multiplex P. falciparum antibody testing could provide estimates of long-term and recent malaria transmission and potentially of a population's susceptibility to future clinical malaria.
Background: The commonly accepted gold standard diagnostic method for detecting malaria is a micr... more Background: The commonly accepted gold standard diagnostic method for detecting malaria is a microscopic reading of Giemsa-stained blood films. However, symptomatic diagnosis remains the basis of therapeutic care for the majority of febrile patients in malaria endemic areas. This study aims to compare the discrepancy in malaria and anaemia burdens between symptomatic diagnosed patients with those diagnosed through the laboratory. Methods: Data were collected from Western Kenya during a follow-up study of 887 children with suspected cases of malaria visiting the health facilities. In the laboratory, blood samples were analysed for malaria parasite and haemoglobin levels. Differences in malaria prevalence between symptomatic diagnosis and laboratory diagnosis were analysed by Chi-square test. Bayesian probabilities were used for the approximation of the malaria and anaemia burdens. Regression analysis was applied to: (1) determine the relationships between haemoglobin levels, and malaria parasite density and (2) relate the prevalence of anaemia and the prevalence of malaria. Results: The prevalence of malaria and anaemia ranged from 10% to 34%, being highest during the rainy seasons. The predominant malaria parasite was P. falciparum (92.3%), which occurred in higher density in children aged 2-5 years. Fever, high temperature, sweating, shivering, vomiting and severe headache symptoms were associated with malaria during presumptive diagnosis. After conducting laboratory diagnosis, lower malaria prevalence was reported among the presumptively diagnosed patients. Surprisingly, there were no attempts to detect anaemia in the same cohort. There was a significant negative correlation between Hb levels and parasite density. We also found a positive correlation between the prevalence of anaemia and the prevalence of malaria after laboratory diagnosis indicating possible co-occurrence of malaria and anaemia. Conclusion: Symptomatic diagnosis of malaria overestimates malaria prevalence, but underestimates the anaemia burden in children. Good clinical practice dictates that a laboratory should confirm the presence of parasites for all suspected cases of malaria.
Objective: To establish the intensity, duration and frequency of exercise needed to achieve chang... more Objective: To establish the intensity, duration and frequency of exercise needed to achieve change in metabolic profiles of pre-diabetes at Moi Teaching and Referral Hospital, Eldoret, Kenya. Design: A randomized controlled experimental study Setting: Moi Teaching and Referral Hospital, Eldoret, Kenya Subjects: Two comparison groups Experimental Group (EG) and Control Group (CG) with both groups having the same size of subjects, 17 patients each Results: The results showed that training reduces FBG by 5% and 13%, in 6 and 12 weeks, respectively. HDL were significantly higher in the experimental than in the control group during post-training (z= -3.20.17, p=0.001). On the other hand the level of LDL decreased in the experimental group during both mid-training and post-training period relative to pre-training (z= -2.908.18, p=0.001). There was asignificant reduction of Hemoglobin A1c (HbA1c) (of 3%) after six weeks and an even more marked drop (8%) after 12 weeks in EG compared to CG...
Methods: This was a randomized experimental animal study in which twenty four reproductively matu... more Methods: This was a randomized experimental animal study in which twenty four reproductively mature non+ pregnant rats were kept in cages, fed on mice pellets and exposed to 12/12 hours of dark/light cycles. Reproductive cycles of each rat were monitored twice every day by vaginal smear cell profiling for two months before randomly dividing the rats into controls (4) and experimental (20) groups. Rectal temperatures were determined daily and screening for hemoparasites done fortnightly during the two months. Then the experimental rats were each infected with 2.0 x 10 Trypanosoma brucei brucei parasites and the vaginal smear profiling, rectal temperature and parasitaemia monitoring continued for one month. The animals were then sacrificed and the ovaries and brain tissues harvested and processed for histological examination.
Objectives: To investigate the metabolic parameters of pre-diabetes and to provide evidence of pr... more Objectives: To investigate the metabolic parameters of pre-diabetes and to provide evidence of prescribed physical therapy exercises that can be quantified and reproduced. Design: A controlled experimental study Setting: Moi Teaching and Referral Hospital and physical therapy gymnasium of Moi University orthopaedics and rehabilitation department in Uasin Gishu County, Kenya. Subjects: Two comparison groups, Experimental Group (EG) and Control Group (CG) with each group having the same size of subjects (17 each). Results: Exercise reduces Fasting Blood Glucose (FBG) by 5% and 13%, in 6 and 12 weeks, respectively. It also showed High Density Lipoprotein (HDL) were significantly higher in the experimental than in the control group during post-training (z= -3.20.17, p=0.001). On the other hand, the level of Low-Density Lipoprotein (LDL) decreased in the experimental group during both mid-training and post-training period relative to pre-training (z= -2.908.18, p=0.001). There was a sign...
Individuals naturally exposed to Plasmodium falciparum lose clinical immunity after a prolonged l... more Individuals naturally exposed to Plasmodium falciparum lose clinical immunity after a prolonged lack of exposure. P. falciparum antigen-specific cytokine responses have been associated with protection from clinical malaria, but the longevity of P. falciparum antigen-specific cytokine responses in the absence of exposure is not well characterized. A highland area of Kenya with low and unstable malaria transmission provided an opportunity to study this question. The levels of antigen-specific cytokines and chemokines associated in previous studies with protection from clinical malaria (gamma interferon [IFN-γ], interleukin-10 [IL-10], and tumor necrosis factor alpha [TNF-α]), with increased risk of clinical malaria (IL-6), or with pathogenesis of severe disease in malaria (IL-5 and RANTES) were assessed by cytometric bead assay in April 2008, October 2008, and April 2009 in 100 children and adults. During the 1-year study period, none had an episode of clinical P. falciparum malaria. ...
American Journal of Tropical Medicine and Hygiene, 2012
In highland areas of unstable, low malaria transmission, the extent to which immunity to uncompli... more In highland areas of unstable, low malaria transmission, the extent to which immunity to uncomplicated malaria develops with age and intermittent parasite exposure has not been well characterized. We conducted active surveillance for clinical malaria during April 2003-March 2005 in two highland areas of western Kenya (Kapsisiywa and Kipsamoite). In both sites, annual malaria incidence was significantly lower in persons 15 years of age than in persons 5 years of age (Kapsisiywa: incidence = 382.9 cases/1,000 persons among persons 1-4 years of age versus 135.1 cases/ 1,000 persons among persons 15 years of age; Kipsamoite: incidence = 233.0 cases/1,000 persons in persons 1-4 years of age versus 43.3 cases/1,000 persons in persons 15 years of age). In Kapsisiywa, among persons with malaria, parasite density and axillary body temperature were also significantly lower in persons 15 years of age than in persons 5 years of age. Even in highland areas of unstable and low malaria transmission, age is associated with development of clinical immunity to malaria.
Tools that estimate recent and long-term malaria transmission in a population would be highly use... more Tools that estimate recent and long-term malaria transmission in a population would be highly useful for malaria elimination programs. The prevalence of antibodies to 11 Plasmodium falciparum antigens was assessed by cytometric bead assay or enzyme-linked immunosorbent assay in 1000 people in a highland area of Kenya over 14 months, during a period of interrupted malaria transmission. Antibodies differed by antigen in acquisition with age: rapid (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;80% antibody positive by age 20 years, 5 antigens), moderate (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;40% positive by age 20 years, 3 antigens), or slow (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;40% positive by age 20 years, 3 antigens). Antibody seroreversion rates in the 14 months between samples decreased with age rapidly (7 antigens), slowly (3 antigens), or remained high at all ages (schizont extract). Estimated antibody half-lives in individuals &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;10 years of age were long (40 to &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;80 years) for 5 antigens, moderate (5-20 years) for 3 antigens, and short (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;1 year) for 3 antigens. Antibodies to P. falciparum antigens in malaria-endemic areas vary by age, antigen, and time since last exposure to P. falciparum. Multiplex P. falciparum antibody testing could provide estimates of long-term and recent malaria transmission and potentially of a population&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s susceptibility to future clinical malaria.
Background. Tools that estimate recent and long-term malaria transmission in a population would b... more Background. Tools that estimate recent and long-term malaria transmission in a population would be highly useful for malaria elimination programs. Methods. The prevalence of antibodies to 11 Plasmodium falciparum antigens was assessed by cytometric bead assay or enzyme-linked immunosorbent assay in 1000 people in a highland area of Kenya over 14 months, during a period of interrupted malaria transmission. Results. Antibodies differed by antigen in acquisition with age: rapid (>80% antibody positive by age 20 years, 5 antigens), moderate (>40% positive by age 20 years, 3 antigens), or slow (<40% positive by age 20 years, 3 antigens). Antibody seroreversion rates in the 14 months between samples decreased with age rapidly (7 antigens), slowly (3 antigens), or remained high at all ages (schizont extract). Estimated antibody half-lives in individuals >10 years of age were long (40 to >80 years) for 5 antigens, moderate (5-20 years) for 3 antigens, and short (<1 year) for 3 antigens. Conclusions. Antibodies to P. falciparum antigens in malaria-endemic areas vary by age, antigen, and time since last exposure to P. falciparum. Multiplex P. falciparum antibody testing could provide estimates of long-term and recent malaria transmission and potentially of a population's susceptibility to future clinical malaria.
Background: The commonly accepted gold standard diagnostic method for detecting malaria is a micr... more Background: The commonly accepted gold standard diagnostic method for detecting malaria is a microscopic reading of Giemsa-stained blood films. However, symptomatic diagnosis remains the basis of therapeutic care for the majority of febrile patients in malaria endemic areas. This study aims to compare the discrepancy in malaria and anaemia burdens between symptomatic diagnosed patients with those diagnosed through the laboratory. Methods: Data were collected from Western Kenya during a follow-up study of 887 children with suspected cases of malaria visiting the health facilities. In the laboratory, blood samples were analysed for malaria parasite and haemoglobin levels. Differences in malaria prevalence between symptomatic diagnosis and laboratory diagnosis were analysed by Chi-square test. Bayesian probabilities were used for the approximation of the malaria and anaemia burdens. Regression analysis was applied to: (1) determine the relationships between haemoglobin levels, and malaria parasite density and (2) relate the prevalence of anaemia and the prevalence of malaria. Results: The prevalence of malaria and anaemia ranged from 10% to 34%, being highest during the rainy seasons. The predominant malaria parasite was P. falciparum (92.3%), which occurred in higher density in children aged 2-5 years. Fever, high temperature, sweating, shivering, vomiting and severe headache symptoms were associated with malaria during presumptive diagnosis. After conducting laboratory diagnosis, lower malaria prevalence was reported among the presumptively diagnosed patients. Surprisingly, there were no attempts to detect anaemia in the same cohort. There was a significant negative correlation between Hb levels and parasite density. We also found a positive correlation between the prevalence of anaemia and the prevalence of malaria after laboratory diagnosis indicating possible co-occurrence of malaria and anaemia. Conclusion: Symptomatic diagnosis of malaria overestimates malaria prevalence, but underestimates the anaemia burden in children. Good clinical practice dictates that a laboratory should confirm the presence of parasites for all suspected cases of malaria.
Objective: To establish the intensity, duration and frequency of exercise needed to achieve chang... more Objective: To establish the intensity, duration and frequency of exercise needed to achieve change in metabolic profiles of pre-diabetes at Moi Teaching and Referral Hospital, Eldoret, Kenya. Design: A randomized controlled experimental study Setting: Moi Teaching and Referral Hospital, Eldoret, Kenya Subjects: Two comparison groups Experimental Group (EG) and Control Group (CG) with both groups having the same size of subjects, 17 patients each Results: The results showed that training reduces FBG by 5% and 13%, in 6 and 12 weeks, respectively. HDL were significantly higher in the experimental than in the control group during post-training (z= -3.20.17, p=0.001). On the other hand the level of LDL decreased in the experimental group during both mid-training and post-training period relative to pre-training (z= -2.908.18, p=0.001). There was asignificant reduction of Hemoglobin A1c (HbA1c) (of 3%) after six weeks and an even more marked drop (8%) after 12 weeks in EG compared to CG...
Methods: This was a randomized experimental animal study in which twenty four reproductively matu... more Methods: This was a randomized experimental animal study in which twenty four reproductively mature non+ pregnant rats were kept in cages, fed on mice pellets and exposed to 12/12 hours of dark/light cycles. Reproductive cycles of each rat were monitored twice every day by vaginal smear cell profiling for two months before randomly dividing the rats into controls (4) and experimental (20) groups. Rectal temperatures were determined daily and screening for hemoparasites done fortnightly during the two months. Then the experimental rats were each infected with 2.0 x 10 Trypanosoma brucei brucei parasites and the vaginal smear profiling, rectal temperature and parasitaemia monitoring continued for one month. The animals were then sacrificed and the ovaries and brain tissues harvested and processed for histological examination.
Objectives: To investigate the metabolic parameters of pre-diabetes and to provide evidence of pr... more Objectives: To investigate the metabolic parameters of pre-diabetes and to provide evidence of prescribed physical therapy exercises that can be quantified and reproduced. Design: A controlled experimental study Setting: Moi Teaching and Referral Hospital and physical therapy gymnasium of Moi University orthopaedics and rehabilitation department in Uasin Gishu County, Kenya. Subjects: Two comparison groups, Experimental Group (EG) and Control Group (CG) with each group having the same size of subjects (17 each). Results: Exercise reduces Fasting Blood Glucose (FBG) by 5% and 13%, in 6 and 12 weeks, respectively. It also showed High Density Lipoprotein (HDL) were significantly higher in the experimental than in the control group during post-training (z= -3.20.17, p=0.001). On the other hand, the level of Low-Density Lipoprotein (LDL) decreased in the experimental group during both mid-training and post-training period relative to pre-training (z= -2.908.18, p=0.001). There was a sign...
Individuals naturally exposed to Plasmodium falciparum lose clinical immunity after a prolonged l... more Individuals naturally exposed to Plasmodium falciparum lose clinical immunity after a prolonged lack of exposure. P. falciparum antigen-specific cytokine responses have been associated with protection from clinical malaria, but the longevity of P. falciparum antigen-specific cytokine responses in the absence of exposure is not well characterized. A highland area of Kenya with low and unstable malaria transmission provided an opportunity to study this question. The levels of antigen-specific cytokines and chemokines associated in previous studies with protection from clinical malaria (gamma interferon [IFN-γ], interleukin-10 [IL-10], and tumor necrosis factor alpha [TNF-α]), with increased risk of clinical malaria (IL-6), or with pathogenesis of severe disease in malaria (IL-5 and RANTES) were assessed by cytometric bead assay in April 2008, October 2008, and April 2009 in 100 children and adults. During the 1-year study period, none had an episode of clinical P. falciparum malaria. ...
American Journal of Tropical Medicine and Hygiene, 2012
In highland areas of unstable, low malaria transmission, the extent to which immunity to uncompli... more In highland areas of unstable, low malaria transmission, the extent to which immunity to uncomplicated malaria develops with age and intermittent parasite exposure has not been well characterized. We conducted active surveillance for clinical malaria during April 2003-March 2005 in two highland areas of western Kenya (Kapsisiywa and Kipsamoite). In both sites, annual malaria incidence was significantly lower in persons 15 years of age than in persons 5 years of age (Kapsisiywa: incidence = 382.9 cases/1,000 persons among persons 1-4 years of age versus 135.1 cases/ 1,000 persons among persons 15 years of age; Kipsamoite: incidence = 233.0 cases/1,000 persons in persons 1-4 years of age versus 43.3 cases/1,000 persons in persons 15 years of age). In Kapsisiywa, among persons with malaria, parasite density and axillary body temperature were also significantly lower in persons 15 years of age than in persons 5 years of age. Even in highland areas of unstable and low malaria transmission, age is associated with development of clinical immunity to malaria.
Tools that estimate recent and long-term malaria transmission in a population would be highly use... more Tools that estimate recent and long-term malaria transmission in a population would be highly useful for malaria elimination programs. The prevalence of antibodies to 11 Plasmodium falciparum antigens was assessed by cytometric bead assay or enzyme-linked immunosorbent assay in 1000 people in a highland area of Kenya over 14 months, during a period of interrupted malaria transmission. Antibodies differed by antigen in acquisition with age: rapid (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;80% antibody positive by age 20 years, 5 antigens), moderate (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;40% positive by age 20 years, 3 antigens), or slow (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;40% positive by age 20 years, 3 antigens). Antibody seroreversion rates in the 14 months between samples decreased with age rapidly (7 antigens), slowly (3 antigens), or remained high at all ages (schizont extract). Estimated antibody half-lives in individuals &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;10 years of age were long (40 to &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;80 years) for 5 antigens, moderate (5-20 years) for 3 antigens, and short (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;1 year) for 3 antigens. Antibodies to P. falciparum antigens in malaria-endemic areas vary by age, antigen, and time since last exposure to P. falciparum. Multiplex P. falciparum antibody testing could provide estimates of long-term and recent malaria transmission and potentially of a population&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s susceptibility to future clinical malaria.
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