Browsing by Author "Were, Tom"

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    Characterisation of natural immune responses to fal vac-l of plasmodium falciparumin children and adults from a holoendemic area of Western Kenya
    (Kenyatta University, 2000) Were, Tom
    Previous studies indicate that FAL VAC-1, a recombinant multistage and multicomponent Plasmodium falciparum candidate vaccine containing 12 B cell and 9 T cell epitopes from 9 different antigens of different life cycle stages is immunogenic in animal models and that FAL VAC-1-induced antibodies produced significant antiparasite activities against both sporozoite and blood stages of the parasite. In preparation for vaccine trials in humans, a community based cross-sectional study in a malaria holoendemic area of western Kenya was conducted during April-August 1999, to characterise in vitro natural humoral and cellular immune responses to this candidate vaccine and their association with clinical protection against malaria in young children < 2 years old (N= 180) and their non-pregnant mothers aged 15-48 years (N=139). FAL VAC-1 antigen was used in antibody measurement by ELISA and in lymphoproliferative experiments. Prevalence and level of antibodies were significantly higher in adults than in children when stratified by age groups: 0-6 months; 7-12 months, 13-18 months; 19-24 months; 15-25 years and 26-48 years. Total IgG, IgG1, IgG3 and IgM were the predominant antibodies. IgG2 responses were low and no IgG4 was detected. In children, there were higher IgG 1 levels in parasitaemic group than in the aparasitaemic 'group (F=3.459, p=0.024, t-test). Furthermore, total IgG, IgG1, IgG3 and IgM levels were inversely associated with .' . r '. haemoglobin levels at the time of sampling (total IgG, r=-0.215, p=0.005, IgG1, r=- 0.180, p=0.019; IgG3, r=-0.164, p=0.034; IgM, r=-0.216, p=O.OOl). Parasitaemic children had significantly higher IgG 1 levels at a month prior to sampling. In addition, IgG 1 was positively correlated to the rate of high density parasitaemia and to episodes of clinical malaria (r=0.218, p=0.029 and r=0.237, p=0.018), respectively. However, in adults, aparasitaemic individuals had high total IgG, IgG 1 and IgM levels than parasitaemic individuals (total IgG, F=3.856, p=O.007; IgGl, F=2.701, p=O.007; IgM, F=5.133, p=O.OOl,t-test). In addition, IgG2 was inversely associated with haemoglobin levels at the time of sampling. In contrast to antibody responses, lymphoproliferative responses were higher in children than in adults (one-way ANOV A, F=2.392, p=O.038). Generally, lymphocytes from adults responded at lower antigen concentrations, while those from children responded at higher antigen concentrations. There were no associations between lymphoproliferation and malaria infection or haemoglobin level in either young children or adults. The results of this study therefore indicate that: FAL VAC-l, a multistage multicomponent malaria vaccine candidate is recognised by individuals naturally exposed to malaria. The antibody responses increase whereas lymphoproliferative responses decrease with age. The higher IgG1 levels in children may indicate the presence of a current P. falciparum infection, but in adults from the same holoendemic area, IgG 1, may be associated with protection against parasitaemia.
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    Hepatitis B Virus Sero-profiles and Genotypes in HIV-1 Infected and Uninfected Injection and Non-injection Drug Users from Coastal Kenya
    (BioMed Central, 2015) Kilongosi, Mark W.; Budambula, Valentine; Lihana, Raphael; Musumba, Francis O.; Nyamache, Anthony K.; Budambula, Nancy L. M.; Ahmed, Aabid A.; Ouma, Collins; Were, Tom
    Background: Information about HBV sero-markers, infection stages and genotypes in HIV-1 infected and uninfected injection and non-injection drug users (IDUs) in Kenya remains elusive. Methods: A cross-sectional study examining HBV sero-marker, infection stages and genotypes was conducted among HIV-1 infected and uninfected, respectively, IDUs (n = 157 and n = 214) and non-IDUs (n = 139 and n = 48), and HIV-1 uninfected non-drug using controls (n = 194) from coastal, Kenya. HBV sero-marker and infection stages were based on HBV 5-panel rapid test plasma sero-reactivity. DNA was extracted from acute and chronic plasma samples and genotypes established by nested-PCR and direct sequencing. Results: HBsAg positivity was higher in HIV-1 infected IDUs (9.6 %) relative to HIV-1 uninfected IDUs (2.3 %), HIV-1 infected non-IDUs (3.6 %), HIV-1 uninfected non-IDUs (0.0 %) and non-drug users (2.6 %; P = 0.002). Contrastingly, HBsAb positivity was higher in HIV-1 uninfected IDUs (14.6 %) and non-IDUs (16.8) in comparison to HIV-1 infected IDUs (8.3 %), and non-IDUs (8.6 %), and non-drug users (8.2 %; P = 0.023). HBcAb positivity was higher in HIV-1 infected IDUs (10.2 %) compared to HIV-1 uninfected IDUs (3.3 %), HIV-1 infected non-IDUs (6.5 %), HIV-1 uninfected non-IDUs (2.1 %) and non-drug users (4.6 %; P = 0.038). Acute (5.7 %, 1.4 %, 0.0 %, 0.0 % and 1.5 %) and chronic (5.1 %, 0.9 %, 3.6 %, 0.0 % and 1.5 %) stages were higher in HIV-1 infected IDUs, compared to HIV-1 uninfected IDUs, HIV-1 infected and uninfected non-IDUs and non-drug users, respectively. However, vaccine type response stage was higher in HIV-1 uninfected IDUs (15.4 %) relative to HIV-1 infected IDUs (6.4 %), and HIV-1 infected (6.5 %), and uninfected (10.4 %) non-IDUs, and non-drug users (5.7 %; P = 0.003). Higher resolved infection rates were also recorded in HIV-1 uninfected IDUs (11.2 %) compared to HIV-1 infected IDUs (8.3 %), and HIV-1 infected (7.2 %), uninfected (6.3 %) non-IDUs, and non-drug users (6.7 %; P = 0.479), respectively. Only A1 genotype showing minimal diversity was detected among the study participants. Conclusion: HBV sero-markers and infection staging are valuable in diagnosis and genotyping of HBV infections. Among IDUs, higher HBsAg and HBcAb positivity in HIV-1 infected and higher HBsAb positivity in HIV-1 negative IDUs suggests frequent exposure. Additionally, HBV genotype A is the dominant circulating genotype in both high and low risk populations of Kenya.
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    HIV‑1 protease inhibitor drug resistance in Kenyan antiretroviral treatment‑naive and ‑experienced injection drug users and non‑drug users
    (BioMed Central, 2015) Budambula, Valentine; Musumba, Francis O.; Webale, Mark K.; Kahiga, Titus M.; Ongecha‑Owuor, Francisca; Kiarie, James N.; Sowayi, George A.; Ahmed, Aabid A.; Ouma, Collins; Were, Tom
    Background: Although injection drug use drives antiretroviral drug resistance, the prevalence of protease inhibitor (PI) resistance among Kenyan IDUs remains undetermined. We, therefore, explored PI resistance mutations and their association with viral load and CD4+ T cell counts in HIV-1 infected IDUs (ART-naive, n = 32; and -experienced, n = 47) and non-drug users (ART-naive, n = 21; and -experienced, n = 32) naive for PI treatment from coastal Kenya. Results: Only IDUs harboured major PI resistance mutations consisting of L90M, M46I and D30 N among 3 (6.4 %) ART-experienced and 1 (3.1 %) -naive individuals. Minor PI mutations including A71T, G48E, G48R, I13V, K20I, K20R, L10I, L10V, L33F, L63P, T74S, V11I, and V32L were detected among the ART-experienced (36.2 vs. 46.9 %) and -naive (43.8 vs. 66.7 %) IDUs and non-drug users, respectively. All the four IDUs possessing major mutations had high viral load while three presented with CD4+ T cell counts of <500 cells/ml. Among the ART-naive non-drug users, CD4+ T cell counts were significantly lower in carriers of minor mutations compared to non-carriers (P < 0.05). Conclusion: Transmitted drug resistance may occur in IDUs underscoring the need for genotyping resistance before initiating PI treatment.
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    In Vitro Antioxidant Activity of Haloalkaliphilic Fungal Extracts from Lake Magadi, Kenya
    (Science Mundi, 2025) Kiboi, Nathan; Abonyo, Collins; Ouko, Nahashon; Kimani, James; Juma, Kelvin; Ngugi, Mathew Piero; Marera, Domnic; Were, Tom
    The wide-ranging saline-alkaline ecological setting is steadily acquiring appreciation as a rich source harbouring a repertoire of extremophilic fungal diversity exerting exclusive biological activities ranging from anti-inflammatory, antipyretic, analgesic among other varied medicinal capacities. However, studies characterizing biochemical functionalities from structurally unique haloalkaliphilic fungal biota remain scanty and undocumented. Importantly, saline emitting hot-springs situated in Rift valley soda lakes are gaining recognition as natural reservoirs with enormous fungal microbial community bearing potential for antioxidation capacity. Therefore, we conducted a cross-sectional laboratory based experimental study through random sampling aimed at characterizing in vitro antioxidant activity from haloalkaliphilic fungal strains of Lake Magadi in Kenya. Sample types comprising wet sediments, soils and surface water were cultured in sabouraud’s dextrose agar (SDA), potato dextrose agar (PDA) and malt extract agar (MEA) plates at temperatures of 250c and 410c respectively, for 1-3 weeks. Resulting pure isolates underwent molecular identification. PCR proceeded using ITS-1 & 4 universal primers followed by Sanger sequencing. NCBI’s nBLAST supported molecular identification with ≥90% identity cut-off values. Fermentation and extracts production progressed for 28 days at 250c accompanied by lyophilisation. Yielded freeze-dried extracts were profiled for antioxidant activity through hydroxyl, superoxide, DPPH, hydrogen peroxide, FRAP and lipid peroxidation inhibition assays. Extracts’ total phenolics and flavonoids content were also estimated. IC50 was tabulated based on dose-response curves against standards through linear regression. One-way ANOVA compared means across treatments and Tukey’s post hoc used for pairwise group comparisons. Statistical significance was considered at P≤0.05. Genera Cladosporium exhibited dominance (n=4) among sampled fungal biota. Samples P1, P6, P9 and P5 extracts exhibited maximal scavenging activity at higher concentrations against hydroxyl (76.53% ± 1.27), superoxide (78.90% ± 1.29), H202 (76.19% ± 0.40) and DPPH (80.19% ± 0.94) radicals, respectively. Ferric reductive (0.583 ± 0.005) and lipid peroxidation inhibitive (80.95% ± 1.07) activities for isolate P5 was statistically higher relative to other profiled extracts. Radical scavenging capacity of respective antioxidant standards was substantially higher against assayed extracts. Profound IC50 scavenging effect occurred at extract concentrations between 2.5 - 3.5 mg/ml. P7 extracts revealed peak total phenolic content of 3.61 ± 0.05 mg gallic acid equivalents/mg crude extract at 4mg/ml, while P6 expressed comparable total flavonoid content of 3.32 ± 0.04 mg quercetin equivalents/mg crude extract. Overally, fungi extracts showcased free radicals scavenging ability against reactive species in assorted antioxidant assays. Besides safety profile validation, our extracts demonstrate applicability for antioxidative potential that may further be discerned via comparative in vivo and ex vivo murine experimentation models.
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    Natural monocytic acquisition of haemozoin and rantes polymorphisms: association with malarial disease outcomes and functional changes in children from Western Kenya
    (2013-01-30) Were, Tom; Alloys Sigar S. Orago; Otieno, Micheal Frederick; Douglas Jay Perkins
    Plasmodium falciparum is an important cause of morbidity and mortality in children residing in holoendemic transmission areas largely from severe malarial anaemia (SMA). Although overproduction of inflammatory-derived cytokines are implicated in the immunopathogenesis of severe malaria, the chemokine regulated on activation, normal T-cell expressed and secreted (RANTES, CCL5) is largely unexplored in the context of malaria. Additionally, pro-inflammatory cytokines, such as tumour necrosis factor (TNF)-α, interleukin (IL)-1 and interferon (IFN)- promote increased RANTES production, while anti-inflammatory cytokines (e.g., IL-4, IL-10 and IL-13) down-regulate RANTES biosynthesis. However, the effect of these cytokines on RANTES production in children with malaria anaemia (MA) is poorly understood. Although genetic variation in RANTES is associated with inflammatory, autoimmune and infectious diseases, the role of single nucleotide polymorphisms (SNPs) in conditioning disease outcomes and RANTES production in malaria remains unexplored. These studies investigated the relationship between circulating RANTES with MA severity, thrombocytopaenia, suppression of erythropoiesis, and naturallyacquired haemozoin (pfHz) in monocytes. The functional influence of promoter (403G/A, -4120A/T, and -415]C/T) and intronic (+307A/G) SNPs on malaria outcomes was also examined. These hospital-based cross-sectional studies were performed in infants and young children (age <36mos.) enrolled at Siaya District Hospital, western Kenya. RANTES levels in circulation and from peripheral blood mononuclear cell (PBMC) cultures were measured by a 25-plex cytokine assay and enzyme-linked immunosorbent assay, respectively. Genotyping of -4120A/T, - 4151C/T and +307A/G polymorphisms was performed using Taqman® 5'-allelic discrimination assay, while -403G/A was genotyped by polymerase chain reactionrestriction fragment length polymorphism (PCR-RFLP) method. Results presented here show that suppression of circulating RANTES is associated with increasing severity of MA (p=0.002), decreased erythropoiesis (p=0.049), and malaria-induced thrombocytopaenia (p=0.036). Additional results demonstrate that suppression of circulating RANTES is associated with increasing levels of pigment-containing monocytes (PCM) (p=0.035). In vitro experiments indicate that monocytic acquisition of pfHz is associated with suppression of RANTES from PBMC under both baseline (p=0.001) and stimulated conditions (p=0.072). Although high levels of pfHz in monocytes caused reduced production of IFN- (p=0.003) and IL-10 (p=0.010), multivariate modelling revealed that only PCM (p=0.048, =-0.171) and IL-10 (p<0.0001, =-0.476) were independently associated with RANTES. Subsequent experiments in cultured PBMC from children with naturally-acquired Hz revealed that blockade of endogenous IL-10 caused significant increases in RANTES production (p=0.028). Haplotypic constructs of RANTES (+307/-403/-4120/-4151) revealed higher frequencies of SMA (Hb<5.0g/dL) in AGTC carriers (75.0% vs. 21.5%, p=0.010) and lower prevalence of thrombocytopaenia in AATC carriers (15.4% vs. 84.6%, p=0.036). Multivariate logistic regression analyses illustrated increased susceptibility to SMA (Hb<5.0g/dL) in AGTC carriers (OR, 13.4; 95% CI, 1.3-133.6; p=0.027) and protection from thrombocytopaenia in AATC carriers (OR, 0.2; 95% CI, 0.1-1.0; p=0.05). Moreover, circulating RANTES levels were lower in AGTC (p=0.049), and higher in AATC carriers (p=0.043). Taken together, these results demonstrate that thrombocytopaenia and natural monocytic acquisition of pfHz are a source of reduced RANTES that may contribute to suppression of erythropoiesis in children with MA. Additional results presented here demonstrate that genetic variation in RANTES is important for mediating SMA and thrombocytopaenia during P. falciparum infection. These findings have the potential to contribute to better understanding of SMA pathogenesis, and lead to better disease management modalities and/or vaccine development.
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    Plasma interferon-gamma, interleukin-10 and adiponectin levels in HIV-1 and tuberculosis coinfected injection drug users at Bomu Hospital, Mombasa, Kenya
    (Kenyatta University, 2016-06) Kiboi, Nathan; Were, Tom; Juma, Gerald
    Sub-Saharan Africa accounts for high tuberculosis cases that result from widespread HIV infections, which is exacerbated by injection substance use. Immunologically, HIV critically impairs cell-mediated host responses to Mycobacterium tuberculosis. IFN-γ, IL-10 and Acrp30 are key mediators of systemic inflammation. Although circulating IFN- and IL-10 levels are increased, Acrp30 levels are lowered and associated with disease severity among HIV and TB co-infected non-susbstance users. In contrast, circulating IFN- and Acrp30 levels are decreased while IL-10 levels are upregulated among injecting heroin addicts. However, no studies to date have reported on these cytokine profiles among Kenyan HIV-1 and TB co-infected injection drug users. This study, therefore, investigated plasma IFN-γ, IL-10 and Acrp30 levels among IDUs, and their association with CD4+ T cell counts, HIV-1 viral load and BMI. A cross-sectional study was conducted from August, 2012-November, 2013 using 138 participants recruited at Bomu hospital; a major centre for rehabilitation of drug and substance users in Mombasa County. Following informed consent, IDUs were enrolled through respondent driven sampling, snowball and makeshift methods while convenience and purposive sampling were used for recruiting the control group. IDUs and controls were screened for HIV and TB respectively through Determine™ and Bioline™ rapid tests, and Ziehl Neelsen stained sputum smears. Subsequently, the study participants were categorised into: HIV-1/TB coinfected ART-naive (n=9) and -experienced (n=27); HIV-1 mono-infected ARTnaive (n=26) and -experienced (n=13); TB mono-infected (n=21), HIV-1 negative and TB uninfected (n=25) IDUs and controls (n=17). Demographic, drug use information and physical measurements were recorded using assisted interviews. EDTA venous blood samples were collected and used for preparing plasma and enumerating CD4+ T cell counts. Frozen plasma samples were used for determining cytokine concentrations, and HIV-1 viral load. CD4+ T cell counts were enumerated using flow cytometry; cytokine levels were measured using a sandwich ELISA technique, while HIV-1 viral load was determined by RT-PCR, respectively. Across-group comparisons in continuous data were performed using Kruskal Wallis followed by post-hoc Dunn’s tests. Plasma IFN-γ (P<0.0001), IL- 10 (P<0.0001) and Acrp30 (P=0.006) levels differed significantly across groups. IFN-γ levels were high in co-infected ART-naive (P<0.001) and -experienced (P<0.001), and HIV-1 mono-infected ART-experienced (P<0.001) IDUs relative to healthy controls. IL-10 levels were elevated in uninfected IDUs (P<0.001) compared to healthy controls. Acrp30 levels were lower in TB mono-infected (P<0.01) relative to controls. IFN-γ/IL-10 ratio varied across-groups (P<0.0001) and higher in co-infected ART-naive (P<0.001) and -experienced (P<0.001), and HIV-1 mono-infected ART-experienced (P<0.001) compared to uninfected IDUs. The IFN-γ/Acrp30 ratio also differed across groups (P<0.0001) with HIV-1 mono-infected ART-experienced (P<0.001), and co-infected ART-naive xii (P<0.001) and -experienced (P<0.001) IDUs exhibiting higher ratio relative to uninfected IDUs. CD4+ T cells correlated inversely with Acrp30 (=-0.717, P=0.030) levels in TB mono-infected IDUs whereas BMI correlated positively with Acrp30 (=0.523, P=0.022) among co-infected ART-naive IDUs, respectively. Altogether, circulating IFN-, IL-10 and Acrp30 production is altered in ART-naive and -experienced HIV-1 and TB co-infected IDUs, suggesting a role as disease markers in HIV and TB co-infection among IDUs.
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    Reproductive and Lifestyle Characteristics of Kenyan Women Presenting With Precancerous Cervical Lesions: A HospitalBased Case–Control Study
    (East African Health Research Commission, 2019) Muitta, Esther; Were, Tom; Kebira, Anthony N.
    Background: Cervical cancer is a leading cause of cancer in women, accounting for 68% of cancer-related deaths among women in developing countries. Several reproductive, lifestyle and demographic risk factors are associated with increased risk for cervical cancer. This study examined the association of risk factors with precancerous cervical lesion grade in women attending Nakuru County Referral Hospital. Methods: This hospital-based, case-control study was conducted among women aged 20 to 70 years from January to December, 2017. A total of 142 women were recruited into the study and stratified based on precancerous cervical lesion grades based on the Bethesda System as: atypical glandular cells or adenocarcinoma in situ (AGC/AIS, n=8), high-grade squamous intraepithelial lesions (HSIL, n=59), low-grade squamous intraepithelial lesions (LSIL, n=35), and controls (n=40). Structured questionnaires were used to collect information on demographic, reproductive health, and lifestyle characteristics; anthropometric assessments were conducted. Endocervical swabs and scrapings were obtained from the study participants and used for human papillomavirus (HPV)-16/18, and Pap smear screening. Results: Age differed significantly among the study groups, with age rising with higher grade of precancerous lesion. Higher rates of HPV 16/18 infection was associated with presenting with AGC/AIS (n=8, 100.0%), HSIL (n=47, 79.7%), and (n= 29, 82.9%), compared to controls (n=4, 10.0%; P<.001). History of concomitant lower abdominal pain, vaginal bleeding and discharge was associated with higher risk of precancerous lesion in the HSIL group (odds ratio [OR] 8.9; 95% confidence interval [CI], 2.6 to 30.6) and the LSIL group (OR 5.8; 95% CI, 1.8 to 18.8). Bust circumference <99 cm was associated with higher risk of having AGC/AIS (OR 17.4; 95% CI, 1.1 to 276.0), HSIL (OR 5.9; 95% CI, 2.0 to 17.1), and LSIL (OR 2.7; 95% CI, 0.9 to 7.8). Waist circumference <86 cm was associated with higher risk of HSIL (OR, 5.4; 95% CI, 1.9 to 15.4) and LSIL (OR 2.9; 95% CI, 0.9 to 8.2). Having a healthy diet was associated with higher odds of LSIL (OR, 4.2; 95% CI, 1.4 to 12.9), but was not associated with HSIL or AGC/AIS. Conclusion: This study suggests that high-risk HPV 16/18 infection, chronic lower abdominal pain with vaginal bleeding, and decreased upper and lower trunk body mass, are associated with higher risk of precancerous cervical lesions. Integrating targeted cervical cancer screening in routine reproductive health-care services may reduce the risk of developing cervical cancer
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    Socio-demographic and sexual practices associated with HIV infection in Kenyan injection and non-injection drug users
    (BioMed Central, 2018) Budambula, Valentine; Matoka, Charles; Ouma, James; Ahmed, Aabid A.; Otieno, Michael F.; Were, Tom
    Background: Substance use is increasingly becoming prevalent on the African continent, fueling the spread of HIV infection. Although socio-demographic factors influence substance consumption and risk of HIV infection, the association of these factors with HIV infection is poorly understood among substance users on the African continent. The objective of the study was to assess socio-demographic and sexual practices that are associated with HIV infection among injection drug users (IDUs), non-IDUs, and non-drug users (DUs) at an urban setting of coastal Kenya. Methods: A cross-sectional descriptive study was conducted among 451 adults comprising HIV-infected and -uninfected IDUs (n = 157 and 39); non-IDUs (n = 17 and 48); and non-DUs (n = 55 and 135); respectively at coastal, Kenya. Respondent driven sampling, snowball and makeshift methods were used to enroll IDUs and non-IDUs. Convenience and purposive sampling were used to enroll non-DUs from the hospital’s voluntary HIV testing unit. Participant assisted questionnaire was used in collecting socio-demographic data and sexual practices. Results: Binary logistic regression analysis indicated that higher likelihood of HIV infection was associated with sex for police protection (OR, 9.526; 95% CI, 1.156-78.528; P = 0.036) and history of sexually transmitted infection (OR, 5.117; 95% CI, 1.924-13.485; P = 0.001) in IDUs; divorced, separated or widowed marital status (OR, 6.315; 95% CI, 1.334-29.898; P = 0.020) in non-IDUs; and unemployment (OR, 2.724; 95% CI, 1.049-7.070; P = 0.040) in non-drug users. However, never married (single) marital status (OR, 0.140; 95% CI, 0.030-0.649; P = 0.012) was associated with lower odds for HIV infection in non-drug users. Conclusion: Altogether, these results suggest that socio-demographic and sexual risk factors for HIV transmission differ with drug use status, suggesting targeted preventive measures for drug users. Keywords: HIV infection, Injection drug users (IDUs), Non-IDUs, Non-drug users, Socio-demographic and sexual risk practices