Cell and Molecular Biology
https://repository.maseno.ac.ke/handle/123456789/77
2024-03-28T14:58:27ZMolecular determination of Plasmodium falciparum parasites with histidine-rich protein 2/3 gene deletions in a holoendemic area, Siaya county, western Kenya
https://repository.maseno.ac.ke/handle/123456789/5976
Molecular determination of Plasmodium falciparum parasites with histidine-rich protein 2/3 gene deletions in a holoendemic area, Siaya county, western Kenya
ACHIENG’, Sharley Wasena
Malaria remains endemic in western Kenya despite the various control interventions. Accurate diagnosis is key to the treatment and control of malaria. As such, the World Health Organization (WHO) recommends parasite-based confirmation of malaria prior to treatment. Plasmodium falciparum Histidine Rich Protein 2 (PfHRP2) based malaria Rapid Diagnostic tests (mRDTs) kits are commonly used throughout western Kenya as an alternative to microscopy in malaria diagnosis. However, the emergence of P. falciparum isolates with HRP2/3 deletions has threatened the sensitivity and performance of the mRDT kits. In western Kenya, a high transmission holoendemic area, polyclonal P. falciparum infection could be present but masked by the wild type gene. This may lead to both underestimation of deletion prevalence and increase in the spread of parasites with deletion. False negative mRDTs pose a public health threat towards malaria treatment and elimination progress. This is because the proportion of malaria infected patients having these gene deletions will go undetected by the PfHRP2-mRDTs, and therefore remain untreated. Siaya County borders western Uganda, an area where massive reports of HRP2/3 gene deletions have been reported and hence the need to conduct HRP2 surveillance in the study area. The study therefore investigated PfHRP2/3 deletions in a paediatric cohort from Siaya county, in western Kenya. Specifically, the study determined the prevalence of PfHRP2/3 deletion and the relative strain abundance of deleted strains in polyclonal infections, compared P. falciparum parasite densities estimated by qPCR and microscopy and evaluated the performance of the mRDT and microscopy techniques that routinely used for malaria diagnosis in Siaya County, western Kenya. The study being retrospective in nature, archived RBC pellets extracted from EDTA blood of children (n=219) who were previously enrolled in the study was used for DNA extraction. In order to achieve all the objectives, the study utilized one-step multiplex quantitative polymerase chain reaction (qPCR). The multiplex qPCR was designed using three differently labelled TaqMan assays detecting the PfHRP2 (PF3D7_0831800) and PfHRP3 (PF3D7_1372200) genes. Overall, PfHRP2/3 deletions were detected in 12 (5.6%) parasite isolates. The PfHRP2 monoclonal deleted strains were present in 2 isolates (1%) isolates while no parasite isolates harbored PfHRP3 single deletion. Further, 9 (4.1%) isolates had deleted PfHRP2 and 1 (0.5%) had PfHRP3 deleted but were masked in polyclonal infection. The average relative abundance of PfHRP2 deleted parasites was 9.6% while wild type was 90.4% in polyclonal infections. The multiplex qPCR demonstrated a higher ability in detecting malaria parasites compared to microscopy with median (IQR) of 8.28E4 (2.75E6) and 6.24E3 (2.45E4) respectively (P≤0.001). Further, there was a positive correlation between parasite detection by qPCR and microscopy
(r=0.59, P≤0.001). On evaluation of the performance of clinical diagnostic techniques used in Siaya County Referral Hospital (SCRH), microscopy demonstrated a higher diagnostic sensitivity of 97.6% (95%CI, 89.8-105.0) and specificity of 26.0% (95%CI, 22.4-29.6) as compared to mRDT. Cohen Kappa’s test revealed a fair agreement between microscopy and qPCR, (k=0.30, P≤0.001). The study provides evidence of PfHRP2 deleted strains including those that are masked in polyclonal infections and their relative abundance in Siaya County. Further the study highlights microscopy as a more sensitive and specific technique in detecting malaria infection as compared to mRDT test.
Master's Thesis
2023-01-01T00:00:00ZPrevalence and antibiotic susceptibility patterns of cotrimoxazole resistant bacterial uropathogens from Hiv patients attending Maseno mission hospital, western kenya
https://repository.maseno.ac.ke/handle/123456789/5973
Prevalence and antibiotic susceptibility patterns of cotrimoxazole resistant bacterial uropathogens from Hiv patients attending Maseno mission hospital, western kenya
MUSASIA, Philip Sakwa
Urinary tract infections (UTI) are inflammatory disorders within the urinary system due to presence of pathogenic microorganisms. Taking advantage of lowered immunity in Human Immuno-deficiency Virus (HIV) patients, bacterial UTI globally contribute up to 60% of opportunistic infections (OI). Previous HIV related (OI) studies concentrated on malaria and sexually transmitted diseases ignoring UTI. Owing to its wide interceptive range, cotrimoxazole was recommended for prophylaxis by world health organization and has been standard against opportunistic infections. However, with prolonged use, bacterial resistance is being reported. Uncertainty of UTI management following rising reports of bacterial resistance to commonly used drugs in AIDS era is real. This hospital based descriptive study investigated prevalence and antibiotic susceptibility patterns of cotrimoxazole resistant bacterial uropathogens from HIV patients attending Maseno mission hospital in western Kenya where treatment is blindly based on chance and history during clinic visits without laboratory testing. Specifically described bacterial UTI prevalence, determined their response to cotrimoxazole and established antibiotic susceptibility patterns. At interval of six, 354 participants were systematically selected from population of 2000. Mid-stream urine was cultured on cysteine lactose electrolyte deficiency agar and samples obtaining >105 colony forming units determined by colony counters were biochemically characterized before being subjected to cotrimoxazole broth dilution sensitivity testing. Isolates not responding to cotrimoxazole were subjected to disc diffusion susceptibility testing in accordance with Clinical Laboratory Standards Institute’s guidelines. Tables, graphs and charts were used to present generated data which was analyzed alongside structured questionnaire captured demographic information. Prevalence of UTI among HIV patients was 117(33%) where 75.4% originated from females and 25.6% males with Escherichia coli (54.7%) being most encountered. Chi square analysis of bacterial responses to cotrimoxazole evaluated at 95 % confidence level was statistically significant at P<0.05 (x)2 (5)=14.3, p< 0.005 with an average susceptibility of 46.6%. Significantly, study results will serve as reference point for future researchers and medics, formed policy reevaluation for prophylaxis program and enhanced better OI management by establishing susceptibility patterns and suitable antibiograms. Study recommended for constant monitoring profile aetiological bacteria, periodic surveillance of for prophylactic drug and practicing scientifically determined treatment recommending most susceptible gentamicin (80.3%) empirical antibiotic for region with 53.4% resistance
Master's Thesis
2023-01-01T00:00:00ZSero-prevalence of Brucellosis and associated risk factors to Brucella pathogen in Tiaty, Baringo County, Kenya
https://repository.maseno.ac.ke/handle/123456789/5959
Sero-prevalence of Brucellosis and associated risk factors to Brucella pathogen in Tiaty, Baringo County, Kenya
OUMA, Dickens Oloo
Brucellosis is a global zoonotic disease caused by Brucella pathogen, which affects man and animals. The disease has been reported across the world including Kenya. Information regarding the sero-prevalence and risk factors of brucellosis in camels in the pastoral Tiaty is still scanty despite several reported loss of camels due to zoonotic diseases. The main objective of this study was to investigate sero-prevalence of brucellosis, and the Risk factors associated with Brucella pathogen infections in Tiaty Sub-county, Baringo County. Thus a cross-sectional study was conducted in the study area whereby a total of 105 sera samples were collected from camels i five study locations, dominated by camel farmers using a multi stage sampling technique. The samples were tested to detect antibodies against Brucella by competitive immunosorbent assay (cELISA) as per the manufacturer’s instructions. In addition, data, on location of camels, history of retained placenta or abortion, gender, and age was gathered using a questionnaire. DNA extraction and purification was done on the positive samples using the Norgen bacterial genomic DNA isolation kit, then the quality and quantity of DNA were determined according to the manufacturer’s instructions. The data on risk factors was analyzed using chi-squared test (X2) at 95% confidence interval (CI) to investigate the relationship between brucellosis and the risk factors. The overall sero-prevalence of 20.0% was reported in camels. The percentage sero-prevalence per study location indicated that Ribikwo had the highest seroprevalence of 38.1% while Silale recorded the least 14.3%. Chemolingot, Lolyamorok and Kollowa locations recorded 28.6%, 19.0% and 0.0% respectively. The proportions of seropositivity in the study locations were significantly higher which revealed a significant association between sero-positivity of camel brucellosis with the location, (p ═ 0.037). It was revealed that brucellosis was associated with age and gender of the camels, further logistic regression analysis on gender revealed that there was 4 times more likelihood of females being seropositive as compared to males (OR = 4.329, 95% CI = 0.971-19.307, P-value 0.050). Further, logistic regression analysis on age revealed that there was 5.8 times more likelihood of seropositivity of brucellosis occurring in camels < 2 years old compared to those aged 2-3 years and those over 3 years old (OR = 5.845, 95% CI = 1.340-25.489, P-value 0.019). History of abortion was found to have no significant association with camel brucellosis which implies that abortions in camels is mainly not linked to brucellosis. Further logistic regression analysis on the age of the camels found out that there is 0.5 times more likelihood of brucellosis occurring in camels with history of abortion (OR = 0.522, 95% CI = 0.118-2.305, P-value 0.391). The high sero-prevalence reported in this study incriminates cattle, sheep and goats as the source of infection since they are reared in close association with camels. The determinant of brucellosis seropositivity were gender and age of camels. Therefore, brucellosis control programs targeting multiple species cattle, goats’ sheep, and camel should be formulated to curb spread of the disease.
Master's Thesis
2023-01-01T00:00:00ZAssociation between hiv-1 subtypes and drug resistance to first line therapy among individuals with advanced disease in Homa bay county, Kenya
https://repository.maseno.ac.ke/handle/123456789/5958
Association between hiv-1 subtypes and drug resistance to first line therapy among individuals with advanced disease in Homa bay county, Kenya
NYAKUNDI, Nelson Mokay
Human Immunodeficiency Virus-1 remains a public health threat globally, and although antiretroviral therapy has greatly improved the lives of people living with HIV, challenges persist due to high HIV genetic diversity and drug resistance. Analysis of HIV-1 subtypes over time demonstrates high subtype diversity and dynamic changes with variations in drug resistance among different HIV-1 subtypes. Homa Bay County carries one of the highest HIV-1 burdens worldwide, yet up-to-date information on circulating subtypes and subtype-specific drug resistance is lacking. The general objective of this study was to determine the association between HIV-1 subtypes and drug resistance to first-line ART among individuals with advanced disease in Homa Bay County. The study specifically sought to characterize HIV-1 subtypes and recombinants, to determine HIV-1 subtype-specific drug-resistance mutations, and to determine HIV-1 subtype-specific polymorphisms associated with drug resistance among HIV-1 patients on first-line ART in Homa Bay County, Kenya. A facility-based, cross-sectional survey was conducted, enrolling individuals aged 15 years and above, with advanced HIV-1 disease, and who had been on first-line ART for at least 6 months. The sample size determined using Cochran's formula was 70 participants. Plasma samples were analyzed using CAP/CTM real-time PCR for HIV-1 viral load and genotyping was performed on dried blood spots for samples with a viral load ≥1000 copies/mL. A genetic analysis of a 1,084-bp fragment of the HIV-1 pol gene encoding amino acids 6-99 of the protease (PR) and 1-251 of the reverse transcriptase (RT) region from 65 participants was performed using an in-house assay. Drug resistance was determined using the Stanford University HIV Database. Subtypes were identified using phylogenetic analysis and REGA subtyping tool. Fisher’s exact test was used to assess the association between subtypes and drug-resistance mutations. Samples with a significant association were subjected to logistic regression analysis, controlling for regimen. The findings revealed that subtype A1 was most prevalent in 46 patients (70.8%), with lower prevalence rates for subtype D (n=9, 13.8%), recombinants (n=6, 9.2%) and A2 (n=4, 6.2%). No statistically significant association was observed between subtypes and nucleoside reverse transcriptase inhibitor (NRTI) mutations or polymorphisms. However, a notable finding was the lower likelihood of observing NNRTI mutations K101E/H and Y181C/I/V, associated with high-level resistance to Nevirapine (NVP) and Efavirenz (EFV), in subtype A1 than in other subtypes (OR=0.14, 95% CI=0.03-0.60 and OR=0.21, 95% CI=0.06-0.72, respectively). This analysis found that HIV-1 subtypes are associated with resistance mutations, with K101 and Y181 less likely in subtype A. This suggests that areas with a high prevalence of subtype A1 may experience reduced compromised efficacy of NVP and EFV as first-line ART options. This implies that ART choice may need to be tailored to the HIV-1 subtypes. However, further investigations with large sample sizes and longitudinal designs are warranted to confirm this and assess the clinical impact of these subtype-specific differences to inform ART regimen policies effectively.
Master's Thesis
2023-01-01T00:00:00ZEvaluation of anti-leishmanial activities of Olea europaea, Kigelia africana, Terminalia mollis, Croton macrostachyus, and Bridella micrantha extracts
https://repository.maseno.ac.ke/handle/123456789/5914
Evaluation of anti-leishmanial activities of Olea europaea, Kigelia africana, Terminalia mollis, Croton macrostachyus, and Bridella micrantha extracts
WAFULA, Dennis Mukhwana
Leishmaniasis pose a significant medical concern worldwide which if left untreated, can be fatal. Although expensive and toxic, pentavalent antimonial drugs are the first-line treatment for leishmaniasis raising the need to find an alternative. Plants extracts contain several bioactive compounds that may offer alternative therapeutic signifcance to already developed antileismanial drugs. Based on folkloric information, a number of plants such as Olea europaea, Kigelia africana, Terminalia mollis, Croton macrostachyus, and Bridella micrantha are used to cure Leishmaniasis in the endemic regions in Baringo County. However, no studies have been done to find out the phytochemical compounds, as well as the anti-leishmanial properties. The aim of this study was to investigate the anti-leishmanial activity of Olea europaea, Kigelia africana, Terminalia mollis, Croton macrostachyus, and Bridella micrantha extracts. The plants were collected from Marigat in Baringo County (Kenya), air-dried, ground into fine particles, and extracted at the KEMRI Center for Traditional Medicine and Drug Research. Completely randomized design (CRD) was used in the in vivo studies. In vitro investigations were carried on L. major promastigotes to determine inhibitory concentrations (IC50) and Minimum Inhibition Concentrations (MIC) and toxicity on Vero cells. A total of 35 mice, 6 in each experimental group were used. For in vivo bioassays, the mice were injected intradermally on the left posterior footpad with 1×106 stationary phase flagellate forms of cultured L. major, and then housed for 4 weeks to allow disease manifestation. Differences between treatment groups exposed to different drugs were examined using logistic regression for each parameter studied. Phytochemical components of bark of the plants contain glycoside, terpenoids, tannins, flavonoids, steroids, and saponins. T. mollis contaned higher concentration of tannins, phenols, alkaloids, and anthraquinone. The crude extracts from the plants significantly inhibited promastogote and amastigote growth (P ˂ 0.05) after 24 hours of exposure, with the standard drug (Amphotericin B) being the most effective, while T. mollis was highly potent on amastigote among the plant extracts, then, C. macrostachyus, while O. europeae was least effective. Among the plant extracts, T. mollis had the highest efficacy (IC50 = 85.5 mg/l) in promastigote, while the least effective was O. europaea. In amastigotes, T. mollis exhibited the highest anti-amastigote activity (IC50 = 96.5 mg/l). The Leishman Donovan Units (LDU) of the L. major infection was lowest (0.12 × 106) in L. major-infected mice treated with T. mollis, while that of O. europeae was highest (4.12 × 106). After four weeks, mice administered with T. mollis demonstrated the greatest decrease in lesion diameter (0.68 ± 0.07 mm). Therapy with T. mollis, resulted in a considerably greater lesion reduction in mice. After 4 weeks of treatment, mice administered with O. europeae had the smallest reduction in lesion diameters of all the drugs examined. After 24 hours of treatment, the different drugs significantly influenced mammalian cell survival (P ˂ 0.05), with percentage cell viability of herbal medications, B. microstachyus, and O. africana causing the most toxic effects. It is concluded that among the extracts from the back of the five test plants, T. mollis at concentraton 85.5 to 96 mg/l was the most effective against Leishmania infection. Over all, the results obtained from the crude extracts screening, suggest that these may be promising sources for the development of new drugs for controlling leishmaniasis. The study recommends the use of T. mollis as the most effective plant extract in management of leishmaniases.
PhD Theses
2023-01-01T00:00:00ZRelationship between the concentration of microcystin in serum and primary liver cancer in patients attending JOOTRH, Kisumu, Kenya
https://repository.maseno.ac.ke/handle/123456789/5605
Relationship between the concentration of microcystin in serum and primary liver cancer in patients attending JOOTRH, Kisumu, Kenya
CHEMUTAI, Evaline
Microcystins (MCs) are toxins released by unicellular micro-organism known as cyanobacteria. These unicellular micro-organisms flourish in aquatic habitats with warm temperatures and nutrients rich water bodies. Microcystins are known to cause Liver cancer via inhibition of serine-threonine protein phosphatases (PP1 & 2A). Previous studies in China and Serbia have shown an association between MCs and occurrence of primary liver cancer (PLC). However, in Kenya, there is no data that links MCs and occurrence of PLC in humans despite there being an existence of harmful cyanobacteria within Nyanza gulf. This cross- sectional study was therefore carried out to investigate the association of serum microcystins to occurrence of PLC. The specific objectives were to determine the levels of MCs and nutrients within the Nyanza gulf; to determine the levels of serum serine-threonine protein phosphatases (PP 1 & 2A) in PLC patients and controls and to determine the correlation between mcyE and mlrA genes. A total of 40 study participants were enrolled; 20 PLC patients confirmed from JaramogiOgingaOdinga Teaching and Referral Hospital were recruited and 20 controls obtained from the source population giving rise to PLC cases. Their demographic information was obtained through questionnaire. Blood samples were collected and analyzed for total serum-serine-threonine PP1 and 2A levels using enzyme-linked immunosorbent assay. Water samples were collected from three sites along Nyanza gulf; Dunga, Homabay, Mbita; and filtration was done using 0.45 μmmembrane filter using vacuum pump to concentrate phytoplanktons. MC-toxin levels in water were measured using MC-ELISA Kit, whereas Nutrients analysis was done using photometric methods. Total RNA was extracted and quantification of mlrA and mcyE gene expression was done using RT-PCR software. MCs levels were detected using ELISA reader, Nutrients levels were quantified using spectrophotometer; whereas total serine-threonine protein phosphatase quantification were done using ELISA reader and analyzed using independent t-test, while correlation of gene expression analysis was done using Pearson correlation. RESULTS: MCs toxins were present in all samples sites, and their levels exceeded recommended WHO guidelines of 1.0µg/l for quality water safety. Highest MCs levels were detected in Homa/Bay B site (21.4 µg/L) which corresponded to high nitrogen and phosphorus levels within the same station (498.64 µg/L: 136.145 µg/L) respectively. This was followed by Mbita A (13.1 µg/L; TP = 46.14 µg/L; TN = 327.32 µg/L), Homa/Bay A (7.9 µg/L; TP = 100 µg/L; TN = 395.21 µg/L), as well as Dunga B (7.1 µg/L; TP = 84.71 µg/L; TN = 308.37 µg/L) and Mbita B (5.9µg/L; TP = 59 µg/L; TN = 330.47 µg/L). However, Dunga site A had the low level of toxin detection of about (2.2 µg/L, TP = 71.14 µg/L; TN = 247.58 µg/L) despite having high levels of nitrogen. Higher levels of serine-threonine protein phophatase activities were observed in liver cancer patients (103.9 ± 17.83 µg/ml) than in controls (25.91 ± 3.342 µg/ml). The variation was statistically significant (P < 0.05; t38 = 4.298;). Water sample analysis provided evidence of expression of MC-synthesizing gene (mcyE) and MC-biodegrading gene (mlrA). Pearson correlation revealed an insignificant moderate positive relationship between mcyE and mlrA genes, (r = 0.625, P (two-tailed) = 0.053). In conclusion, Nyanza gulf presented a high levels of MCs beyond recommended WHO values (1 µg/L) hence posing a great health risk to riparian communities. This could be attributed to variations in the levels of serine-threonine liver enzyme in PLC patients in the study, due to consumption of MC-contaminated water. Therefore, it is necessary to strengthen the protection and monitoring of drinking water source for effective control of water pollution and safeguarding of human health.
Masters Thesis
2022-01-01T00:00:00ZHEMATOLOGICAL AND BIOCHEMICAL PARAMETERS AS ALTERNATIVE MARKERS OF STOCKING DENSITY- INDUCED STRESS IN CULTURED NILE TILAPIA, (Oreochromis niloticus Linnaeus, 1758) UNDER CULTURE CONDITIONS.
https://repository.maseno.ac.ke/handle/123456789/5548
HEMATOLOGICAL AND BIOCHEMICAL PARAMETERS AS ALTERNATIVE MARKERS OF STOCKING DENSITY- INDUCED STRESS IN CULTURED NILE TILAPIA, (Oreochromis niloticus Linnaeus, 1758) UNDER CULTURE CONDITIONS.
ONYANGO, ELIJA ODHIAMBO
Fish and fisheries play a significant role in meeting nutritional food security, more so of the poor communities in the low and middle income countries (LMIC).Oreochromis niloticusisone the most valuable warm water fishes used in aquaculture systems. Various stressors trigger specific stress responses in O. niloticus. High stocking density (HSD) causes persistent stress response, which brings about inhibited fish breeding, growth, and decreased immune capacity thus decreased yield. Studies have been done in other regions of the world to evaluate the various hematological and biochemical parameters in O. niloticus as markers of stress, thus this study evaluated four specific parameters and to customize them for use by O. niloticus farmers in the Counties boardering Lake Victoria in Kenya. Two specific objectives were evaluated in this study namely; to determine the relative hematological parameter; erythrocyte count in cultured O. niloticus, subjected to stocking density induced stress and to determine the relative biochemical parameters; plasma cortisol, whole blood glucose, and blood electrolytes concentrations in cultured O. niloticus, subjected to stocking density induced stress. Stocking rates for the aquaria was done by matching all the fish for body weight/standard mass, Mean± SD (15 ± 1 g) thus, 150 g and 300 g of body weight/ 0.05 m3aquarium for low stocking density (LSD) and HSD respectively both in triplicates. The fish were cultured for 21 days following 3 days of acclimatization to the laboratory conditions after being obtained from the University`s fish rearing facility by seining technique. The fish were fed on a carbohydrate based feed of chick mash at 18 % protein supplemented with crushed Rastrineobola argentea to 25 % protein at a feed portion of 10 g/kg of life body weight. Blood samples were drawn using cardiac puncture technique from fish anaestethised with 2 – phenoxyethanol at 0.30 ml.l-1 from each aquarium (n = 5) using a large sieve. Erythrocyte counts (n = 18) were assayed for using hemocytometer. Plasma cortisol concentration (ng/ml) (n =18) levels were assayed for by use of Enzyme-Linked Immunosorbent Assay. Whole blood glucose concentration levels (n = 30) were determined using a hand-held One Touch Ultra glucose meter (MD-300) and test strips. Electrolyte concentrations (n =18) were assayed using Sherwood Flame Photometer 410. Whole blood glucose analysis revealed statistical (P< 0.05) difference in the means in HSD and LSD O. niloticus groups. Mean plasma glucose concentration was statistically significantly (P ≤ 0.01) higher for HSD than LSD O. niloticus groups at mean ± SD, 96.84 ± 5.28mgd-1 and 76.80 ± 5.92 mgd-1respectively. One-way Analysis of Variance (ANOVA) was done on the data collected and comparison of significant differences in means done between LSD and HSD at 0.01%. Plasma cortisol levels revealed statistically (P ≤ 0.01) significant values of HSD at mean ± SD, 6.35 ± 0.89ng/ml and 4.49 ± 1.08 ng/ml respectively. One way ANOVA analysis of the true electrolyte means for the LSD and HSDO. niloticus groups revealed significantly (P ˂ 0.05) higher mean at mean ± SD (1.63 ± 0.18 mmol/l) HSD and (1.11 ± 0.08 mmol/l)LSD for Na+, (0.73 ± 0.03 mmol/l)HSD and (0.42 ± 0.02 mmol/l)LSD for K+ with no statistical (P˂ 0.05) difference at mean ± SD (0.13 ± 0.00)HSD and (0.13 ± 0.00)LSD for Ca++.One-Way ANOVA analysis revealed significant (P ˂ 0.05) difference in the erythrocyte count means in LSD and HSD O. niloticus groups at mean ± SD, 7.01 ± 0.77 x 106 mm-3 and 3.36 ± 0.63 x 106 mm-3 respectively. Overally, the findings of this study demonstrate that high HSD increase erythrocyte count, plasma cortisol, whole blood glucose, and Na+ and K+ concentration in O. niloticus fish indicating a marked increase in stress levels. Elevated erythrocyte count, plasma cortisol, whole blood glucose, and Na+ and K+ concentrations can be used as alternative biomarkers for acute stress in O. niloticus produced under aquaculture systems. The findings of this study can help improve aquaculture practices on management of chronic stress in O. niloticus and related Cichlids under industrial aquaculture production through timely diagnosis and deployment of appropriate mitigation measures.
2022-01-01T00:00:00ZPhenotypic and genotypic characterization of salmonella Isolated from Nile tilapia (Oreochromis ni/otics, L.) Along lake Victoria beaches in western Kenya
https://repository.maseno.ac.ke/handle/123456789/5262
Phenotypic and genotypic characterization of salmonella Isolated from Nile tilapia (Oreochromis ni/otics, L.) Along lake Victoria beaches in western Kenya
WANDILl, Sarah Awuor
Enteritis induced by nontyphoidal Salmonella represents major economic and social
problems. Chemotherapeutic selection may have additional consequences for
virulence evolution through acquisition of linked virulence genes. . Various foods have <..-
been implicated as sources of Salmonellosis to humans. These include poultry, eggs,
pork, and fish. Although prevalence of Salmonellosis is high in Western Kenya
around Lake Victoria region, no particular food source has been identified to be
associated with its transmission. Fish is the main source of protein for people living
around the lake. Poor sanitary facilities at fishing beaches are likely to contaminate
the lake waters. In Kenya, established quality control measures exist for export
oriented but not locally consumed fish. The main objective of this study was to
identify Samonella species and to perform their phenotypic and genotypic
characterization in Winam gulf of L. Victoria .. A total of 120 fish specimens were
collected of which 63 were positive for various bacteria isolates as determined by
standard culture techniques and serotyping. Twenty-five (39.7%) were Shigella sp.,
9 (14.3%) Salmonella enterica serotype typhimurium, 4 (6.3%) S. enterica serotype
enteritidis, 7 (11.1 %) S. typhi, 16 (25.4%) Escherichia coli, 1 (1.6%) Proteus sp., and
E. aerogenes respectively. Molecular typing of Salmonella involved the amplification
of the house keeping gene for malic acid dehydogenase (mdh) with specific primers.
Twenty Salmonella isolates had a gel ladder head resolved at 261 bp, which
confirmed presence of malic acid dehydrogenase gene. Bands of 429 bp amplified
regions using random sequence primers STll - STl5 further confirmed presence of
Salmonella species in the isolates. Presence of Salmonella in Oreochromis niloticus
was as a result of contamination of the fish during offloading but not during loading
offshore.This study has provided vital data that is critical in assessing and controlling
the risk associated with the presence of Salmonella in O. niloticus in the study area.
For absolute safety, elimination of initial contamination of fish by enteric pathogens
from the source should be ensured. Hence landing and marketing of fish from beaches
with essential sanitary facilities can reduce the risk of cross contamination. Additional
safety measures should include training in personal hygiene, sanitation and ensuring
water quality.
2009-01-01T00:00:00ZBinding of opsonized immune complexes to Erythrocyte crlicd35 inhibits TNF-a production by restricting immune complex uptake by macro phages
https://repository.maseno.ac.ke/handle/123456789/5259
Binding of opsonized immune complexes to Erythrocyte crlicd35 inhibits TNF-a production by restricting immune complex uptake by macro phages
ODERA, Michael Malenya
Previous studies have shown that children suffering from severe malaria have elevated
concentrations of TNF-a, increased levels of circulating immune complexes (ICs) and
decreased levels of complement regulatory proteins (mainly CRl /CD35 and DAF/
CD55) on their erythrocytes. The cross-linking of FcR on the macrophages has been
shown to cause activation and subsequently induce release of pro-inflammatory cytokines
which could lead to malarial anemia, a major complication of P. falciparum and an
important cause of child mortality and morbidity. In this study, it was postulated that the
erythrocytes of individuals suffering from or at the risk of severe malarial anemia have
reduced levels of complement regulatory proteins and this compromises their ability to
mop out circulating ICs. As a result, a lot of ICs remain in circulation, engage the
macrophages and induce the secretion of TNF-a which is associated with malarial
anemia. Using anti-CRI monoclonal antibody, erythrocyte CRI copy numbers were
determined by flow cytometry and cryopreserved erythrocytes from a cross sectional
study in Kombewa were categorized as low, medium 'and high expressers. 15 individuals
from each cohort were selected and IC binding capacity determined by flow cytometry.
Using an in vitro model system, macrophages were stimulated with a cocktail of
erythrocytes and pre-opsonized BSA-anti-BSA ICs, loaded erythrocytes, supernatants
and relevant controls. At the end of 8-hour incubation period, the supernatants were
harvested and ELISA done to determine the levels of TNF-a present. The data generated
in this study indicated that the IC binding capacity was influenced by the CRI copy
number and it was complement dependent. The data did show that the erythrocytes
inhibit IC-induced TNF-a production by macrophages and that the buffering capacity was
in a manner proportional to the level of CRI. Also, the erythrocytes soaked with ICs
stimulated macrophages more than plain erythrocytes though the stimulation was not in a
manner proportional to CRI. Based on the findings it was concluded that erythrocyte
CRI may act as a dynamic buffering system which prevents ICs from stimulating
macrophages to release TNF-a which is implicated in the pathogenesis of severe malaria.
Also, the CRI enables the erythrocytes to soak in ICs and in the process makes the
erythrocytes to become stimulatory leading to secretion of TNF-a by the macrophages
2008-01-01T00:00:00ZThe functional associations between il-4 -589t/c and Il-6 -636g/c promoter polymorphisms and paediatric Severe malarial anaemia in a holoendemic area of Western Kenya
https://repository.maseno.ac.ke/handle/123456789/5256
The functional associations between il-4 -589t/c and Il-6 -636g/c promoter polymorphisms and paediatric Severe malarial anaemia in a holoendemic area of Western Kenya
NDEGE, Henry Onyango
Plasmodium falciparum, the most virulent and lethal human malaria parasite, IS
responsible for most malaria-related morbidity and mortality in sub-Saharan Africa. It
manifests mainly as severe malarial anaemia (SMA) in children in malaria holoendemic
areas such as western Kenya. So far, few studies have investigated genetic
polymorphism in cytokines, which are important determinants of immune response
regulation. Since previous studies have suggested that interleukin-4 (IL-4) and IL-6
production and their interactions seem to playa significant role in the pathogenesis of
severe malaria, this study investigated the fuctional effects of IL-4 -589T/C and IL-6 -
636G/C gene promoter single nucleotide polymorphisms (SNPs) on IL-4 and IL-6
cytokine production and their associations with SMA and high-density parasitaemia
(HDP) during malaria infections. This was a cross-sectional study based at Siaya District
Hospital (SDH) and a total of 618 and 602 study participants were studied for IL-4 -
589T/C and IL-6 -636G/C SNPs, respectively. The study participants were grouped as
aparasitaemic controls (AC), low density parasitaemia (LDP), HDP, SMA and nonsevere
malarial anaemia (Non-SMA). This was after the study participants had met the
inclusion criteria which considered their natural exposure to P. falciparum, prior
hospitalisation, intended relocation, being P. falciparum positive or negative and signing
of the consent forms by parents/guardians, amongst others. Three millilitres of venous
blood samples were collected (in ethylene diamine tetracetic acid (EDT A) vacutainer
tubes and tubes without anticoagulants) from aparasitaemic children and malaria
parasitemic children presenting at SDH and were used for clinical, immunological, and
molecular evaluations, including haemogl~ electrophoresis, genotyping, full
haemogram and cytokine profile anal~es. The IL-4 -589T/C and IL-6 -636G/C
genotyping was carried out using a Taqman S' allelic discrimination by real time PCR.
Human Cytokine Twenty-Five Plex Antibody Bead Kit and a haematological analyzer
were used to determine the cytokine levels and blood cell indices, respectively. The data
were analysed by SPSS software. Kruskal Wallis test and the Marin-Whitney U tests
were used for across group and pairwise comparisons, respectively. Proportionality was
tested by X2 tests, while multivariate logistic regression analysis was used for determining
the associations between the genotypes and malaria clinical outcomes, in a model
controlling for the confounders (age, gender, sickle-cell trait, bacteremia and HIV status).
Results showed that IL-4 -589T/C SNP was significantly associated with increased
susceptibility to HDP (OR; 1.64, 95%CI; 1.01-2.65, P=0.044); however, the IL-6 -
636G/C SNP was not associated with any malaria disease outcome. In addition, the IL-4
-589T/C and IL-6 -636G/C SNPs were not functionally associated with circulating IL-4
and IL-6 levels, respectively. The significant departure from the Hardy-Weinberg
equilibrium (HWE) shown by the IL-4 -589T/C and IL-6 -636G/C genotypic
distributions, implicate the action of evolutionary forces on the genes, possibly through
the exposure of the population to malaria. In conclusion, the variation in the IL-4
promoter region as found in this tudy seems to be conditioning the clinical outcomes of
fa1ciparum malaria and as a result, should be useful in the development of novel
interventions for the control and management of severe malaria. The results of IL-6 -
636G/C SNP from this study, .on the other hand; has shown that the polymorphism
neither conditions malaria disease outcomes nor circulating IL-6 levels in this population,
thus necessitating studies on additional IL-6 SNPs.
2009-01-01T00:00:00Z