Publications by authors named "Naomi Maina"

26 Publications

  • Page 1 of 1

anticoccidial activity of nanoencapsulated bromelain against spp. oocysts isolated from goats in Kenya.

Vet World 2022 Feb 22;15(2):397-402. Epub 2022 Feb 22.

Department of Molecular Biology and Biotechnology, Pan-African University of Institute of Basic Science, Technology and Innovation, Nairobi, Kenya.

Background And Aim: The emergence of drug-resistant strains of spp. calls for the development of novel anticoccidial drugs. Plant extracts provide a possible natural source for such drugs. This study aimed to investigate the anticoccidial activity of encapsulated bromelain (EB) in chitosan nanocarriers on spp. oocysts isolated from goats kept by farmers in Kenya.

Materials And Methods: Bromelain was extracted from the peel of ripe pineapples using standard methods. spp. oocysts were isolated from the feces of goats using a flotation method. The inhibition of sporulation was assayed after exposing the oocysts to solutions of EB, non-EB (NEB), and diclazuril (positive control) at concentrations between 4 mg/mL and 0.125 mg/mL for 48 h. The oocysts were examined under a microscope (40x) to determine the effects of the drugs on the sporulation process. The percentage of sporulation inhibition was calculated after 48 h and the inhibition concentration 50% (IC) was determined by probit analysis.

Results: Bromelain manifested anticoccidial activity through the inhibition of the sporulation of coccidia oocysts. EB achieved inhibition with a lower dose compared with NEB. The IC values of diclazuril, EB, and NEB were 0.078 mg/mL, 0.225 mg/mL, and 0.575 mg/mL, respectively. There were significant differences (p<0.01) between the IC of EB and NEB compared with the standard treatment drug.

Conclusion: This preliminary study showed that EB has anticoccidial activity supporting further evaluation at an level to develop a novel drug for the management of coccidiosis in goats.
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http://dx.doi.org/10.14202/vetworld.2022.397-402DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8980396PMC
February 2022

Evaluation of Analgesic Activities of Extracts of Two Marine Molluscs: var radula (Linnaeus) and (Müller).

J Pain Res 2020 30;13:2739-2747. Epub 2020 Oct 30.

Biochemistry Department, Jomo Kenyatta University of Agriculture and Technology, Juja, Kenya.

Purpose And Methods: In this study, the analgesic activity of the crude alcohol (acetone-methanol) and aqueous (in PBS, pH 7.2) extracts of the marine molluscs, and has been evaluated using the formalin test (for chronic antinociceptive) and the tail-flick (acute antinociceptive) pain models in male swiss albino mice.

Results: The results show that the extracts of and demonstrated high safety margins as single doses of up to 2000 mg/kg bwt proved to be well tolerated and non-lethal, although the alcohol extract of caused necrosis in the liver and kidney when administered at a dose level of 2000 mg/kg bwt. In the formalin test, treatment with the aqueous extracts of and as well as the alcohol extract of 30 min before the subcutaneous injection of 5% formalin to the paw of the mice resulted in a significant time- and dose-dependent reduction in total and phase 2a pain-related behavior and thus nociception. The extracts had no analgesic effect in tail-flick test up to the highest dose tested.

Conclusion: Hence, the results from both models indicate that the site of their analgesic action is probably peripheral.
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http://dx.doi.org/10.2147/JPR.S271458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7608598PMC
October 2020

β-lactam resistance in bacteria associated with subclinical mastitis in goats in Thika Subcounty, Kenya.

Vet World 2020 Jul 25;13(7):1448-1456. Epub 2020 Jul 25.

Department of Animal Sciences, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.

Aim: This study determined the resistance pattern to β-lactam antibiotics of bacteria isolated from goats with subclinical mastitis in Thika subcounty, Kenya. We also administered a questionnaire to assess the risk factors associated with the occurrence of resistance to commonly used antibiotics.

Materials And Methods: We collected milk samples from 110 lactating dairy goats in Thika subcounty to screen for subclinical mastitis using the California mastitis test. Bacterial isolation and identification were performed according to colony morphology, the hemolytic pattern on sheep blood agar, lactose fermentation on MacConkey plates, Gram staining, and standard biochemical tests. The antibiotic susceptibility of the isolates was determined by the agar disk diffusion method using penicillin G, cephalexin, cefoxitin, and cefotaxime antibiotic disks. The double-disk synergy test using amoxicillin-clavulanic acid was employed as a confirmatory test for extended-spectrum β-lactamase (ESBL) production. Fisher's exact test was used to determine the risk factors associated with the occurrence of antibiotic resistance (p≤0.05 was considered significant).

Results: Of the 110 dairy goats sampled, 72.7% (80) were positive for subclinical mastitis. Isolation and identification of the bacteria from the positive samples yielded 149 bacteria isolates, including , , spp., spp., coagulase-negative staphylococci, and . A high percentage (76.5%, 114/149) of the bacterial isolates was resistant to at least one of the tested antibiotics. At least 56/106 isolates (52.8%) showing cross-resistance to the β-lactam antibiotics were resistant to all four of the tested antibiotics, while only one isolate was resistant to three antibiotics (penicillin G, cephalexin, and cefoxitin). The double-disk synergy test confirmed that none of the isolates possessed ESBLs. Pre- and post-milking practices (p=0.0336) were found to be significantly associated with the occurrence of antibiotic resistance.

Conclusion: A large proportion of the goats in our study cohort were infected with β-lactam-resistant bacteria associated with subclinical mastitis. Because the identified bacteria are of zoonotic importance, further studies should be undertaken to determine the transmission dynamics between humans and livestock and to identify novel intervention strategies.
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http://dx.doi.org/10.14202/vetworld.2020.1448-1456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7429379PMC
July 2020

A Review on the Present Advances on Studies of Toxoplasmosis in Eastern Africa.

Biomed Res Int 2020 6;2020:7135268. Epub 2020 Jul 6.

Department of Public Health, Jomo Kenyatta University of Agriculture and Technology, College of Health Sciences, Nairobi, Kenya.

Toxoplasmosis is a zoonotic infection caused by the protozoan parasite, . It was discovered over 100 years ago and is credited as the most successful parasitic organism worldwide, able to infect and multiply in all warm blooded animals including an estimated 2.3 billion people. Toxoplasmosis is asymptomatic in immunocompetent individuals. Infection in the developing fetus and immunocompromised individuals can cause severe clinical disease. Toxoplasmosis is also a major cause of reproductive failure in livestock. The economic impact of toxoplasmosis is believed to be substantial. Factors associated with toxoplasmosis infection have been defined. Eastern Africa region is a high-risk area mainly due to the close association of humans and livestock as well as sociocultural practices, poor environmental hygiene, and poverty. The present paper provides a narrative review of published data on toxoplasmosis in Eastern Africa.
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http://dx.doi.org/10.1155/2020/7135268DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7364236PMC
April 2021

Toxicity and anthelmintic efficacy of chitosan encapsulated bromelain against gastrointestinal strongyles in Small East African goats in Kenya.

Vet World 2020 Jan 25;13(1):177-183. Epub 2020 Jan 25.

Department of Animal Sciences, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.

Background And Aim: The development of resistance to anthelmintic drugs has prompted research into alternative methods of controlling intestinal nematodes in ruminants. This study aimed at evaluating the and anthelmintic efficacy and toxicity of chitosan encapsulated bromelain in Small East African goats in Kenya.

Materials And Methods: Adult mortality assay was performed using live worms treated with encapsulated bromelain solution ranging from 0.125 mg/ml to 2 mg/ml. Percentage mortality of worms was calculated after 24 h and the lethal concentration 50% (LC) determined. For the study, 18 healthy male indigenous goats were divided into six groups of three goats each. The encapsulated bromelain was orally administered in increasing dosages (3-30 mg kg) once daily, for 14 days. The packed cell volume (PCV), aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, creatinine, and fecal egg count (FEC) were determined on a weekly basis. At the end of the study, the goats were sacrificed and gross pathology and histopathology of main organs assessed.

Results: Albendazole had the highest (p<0.05) anthelmintic effect on the worms. An LC of 0.05 mg/ml, 0.445 mg/ml, and 0.155 mg/ml was observed for albendazole, plain bromelain, and encapsulated bromelain, respectively. The PCV of treated and untreated goats did not show any significant difference (p>0.05), varied from 29.3% to 35.1%, and was within the normal range of the animal. Likewise, no significant differences (p>0.05) were observed between the AST, ALT, urea, and creatinine levels of treated and the control (non-treated) goats. No adverse clinical symptoms, toxicity of the main organs, and mortality in goats were associated with the chitosan encapsulated bromelain after administration of dose up to 30 mg/kg for 14 days. Therefore, the lethal dose 50 of encapsulated bromelain may be considered to be >30 mg/kg. On day 28 post-treatment, the encapsulated bromelain showed a higher FEC reduction (68.8%) as compared to the plain bromelain (32.4%).

Conclusion: Our results show that bromelain encapsulated in chitosan may be safe and effective in reducing the burden of gastrointestinal tract strongyle nematodes in goats. However, there is a need for further studies to establish the dosage of the encapsulated bromelain to be administered in a single dose for the treatment of goats against gastrointestinal strongyles. In addition, species-specific studies on the efficacy of encapsulated bromelain on strongyles are necessary to evaluate its effectiveness against the entire Strongyloididae family.
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http://dx.doi.org/10.14202/vetworld.2020.177-183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7020136PMC
January 2020

Development and Evaluation of Epitope-Blocking ELISA for Detection of Antibodies against Contagious Caprine Pleuropneumonia in Goat Sera.

Vet Sci 2019 Oct 18;6(4). Epub 2019 Oct 18.

Laboratoire Central Veterinaire, Laboratoire de Virologie, B.P. 206 Bingerville, Côte d'Ivoire.

Enzyme linked immunosorbent assays (ELISAs) have been developed for the detection of antibodies against contagious caprine pleuropneumonia (CCPP), the causative agent of which is subsp. (Mccp). The currently available commercial CCPP competitive ELISA (CCPP cELISA) kit produced and supplied by IDEXX Company (Westbrook, Maine, United States) is relatively expensive for most African laboratories. To address this issue and provide a variety of choices, a sensitive and specific blocking-ELISA (b-ELISA) test to detect antibodies against CCPP was developed. We describe the newly developed CCPP blocking-ELISA based on the blocking of an epitope of a monoclonal antibody (Mccp-25) by a positive serum sample against the Mccp protein coated on a plate. The Percentage Inhibition (PI) cut-off value for the CCPP b-ELISA was set at 50 using 466 CCPP negative and 84 CCPP positive small ruminant sera. Of the negative sera, 307 were obtained from the Botswana National Veterinary Laboratory (BNVL) and 159 from the Friedrich-Loeffler-Institute (FLI) Germany. The 84 positive sera samples came from experimentally vaccinated goats at the AU-PANVAC facility in Debre-Zeit, Ethiopia. The relative diagnostic sensitivity and specificity of the CCPP b-ELISA was 93% and 88%, respectively. This test result indicated good correlation with that of the commercial CCPP cELISA by IDEXX Company (Westbrook, Maine, United States) with a Cohen's κ agreement of κ agreement of 0.85. The newly developed CCPP b-ELISA will be useful in the detection of antibodies for the diagnosis CCPP and for sero-surveillance during vaccination campaigns.
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http://dx.doi.org/10.3390/vetsci6040082DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6958372PMC
October 2019

In vitro antiproliferative studies of extracts of the marine molluscs: Tympanatonus fuscatus Var radula (linnaeus) and Pachymelania aurita (muller).

Int J Biochem Mol Biol 2019 15;10(1):1-8. Epub 2019 Apr 15.

Biochemistry Department, Jomo Kenyatta University of Agriculture and Technology Juja, Kenya.

This study aimed to investigate the antimitotic and antiproliferation activities of crude acetone-methanol and aqueous extracts of two marine molluscs commonly found in the Niger Delta region of Nigeria; and , against human cancerous cell lines (DU145, Hep-2, and HCC1395) cell lines . The antimitotic activity of the extracts was evaluated using cepa root meristematic cells. Antiproliferative activity of the plant extracts against the cancerous cell lines was compared with normal cell line (VeroE6). Doxorubicin was used as a positive control. Gene expression studies using qPCR for the proapoptotic genes, CASP3, CASP8 and P53 were also carried out. The alcohol extract of (TFAC) exhibited the most promising activity against all the cancer cell lines tested (DU145 IC = 96.48 ± 1.36 μg/ml, HCC 1395 IC = 61.44 ± 2.45 μg/ml, Hep2 IC = 0.52 ± 0.36 μg/ml) and also had the highest selectivity index of 4.94, 7.78 and 921.97 for DU145, HCC 1395 and Hep-2 cells respectively. Furthermore, TFAC was the only extract that significantly upregulated the expression of caspase 3, caspase 8 and P53. Thus, these findings suggest potential exploitation of TFAC as an anticancer agent.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6526377PMC
April 2019

Prevalence, Risk Factors, and Antibiogram of Bacteria Isolated from Milk of Goats with Subclinical Mastitis in Thika East Subcounty, Kenya.

J Vet Med 2018 11;2018:3801479. Epub 2018 Nov 11.

Department of Animal Sciences, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.

A cross-sectional study was carried out to determine the prevalence and risk factors of subclinical mastitis in dairy goats in Thika East Subcounty, Kenya. Further the bacterial pathogens and their antibiogram were investigated. Farm level data on risk factors were obtained from 41 farmers using questionnaires. Milk was obtained from 110 lactating dairy goats and tested for submastitis using California Mastitis Test (CMT). The prevalence of subclinical mastitis at goat level was estimated to be at 50.9% using CMT, out of which 86.5% yielded bacteria on culture. The significant risk factors associated with the occurrence of subclinical mastitis were cleaning schedule (p=0.022, OD=1.047) and parity of the goat (p=0048, OD=1.37). Higher prevalence of subclinical mastitis was observed for goats residing in houses cleaned at least once a fortnight. Does in the first parity were least affected. 169 bacterial isolates were obtained from culture, of which 52 isolates from major classes of isolated bacteria were tested for antibiotic sensitivity to six antibiotics. Fourteen different bacteria were isolated and identified from the milk samples. Coagulase-negative (20.7%), spp. (19.5%), spp. (16%), spp. (11%), (10.7%), spp. (6.5%), (5.9%), spp. (3%), spp. (1.8%), spp. (1.8%), spp. (1.2%), spp. (0.6%), spp. (0.6%), and (0.6%) were isolated and identified from the samples. All the isolates were resistant to Penicillin G, while 98% of the isolates were sensitive to Streptomycin. In conclusion, the study showed that a large proportion of goats were affected by subclinical mastitis, with the main bacteria being spp. and coliforms, and that most of the tested antibiotics can be used in the treatment of mastitis. Farmers need to be trained on improved control of mastitis through adoption of good dairy husbandry and milking practices.
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http://dx.doi.org/10.1155/2018/3801479DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6252223PMC
November 2018

Antimycoplasmal Activities of Compounds from and against Strains from the Cluster.

Front Pharmacol 2017 21;8:920. Epub 2017 Dec 21.

Biosciences Eastern and Central Africa, International Livestock Research Institute, Nairobi, Kenya.

Infections caused by species belonging to the cluster' negatively affect the agricultural sector through losses in livestock productivity. These strains are resistant to many conventional antibiotics due to the total lack of cell wall. Therefore, there is an urgent need to develop new antimicrobial agents from alternative sources such as medicinal plants to curb the resistance threat. Recent studies on extracts from and revealed interesting antimycoplasmal activities hence the motivation to investigate the antimycoplasmal activities of constituent compounds. The CHCl/MeOH extracts from the berries of yielded a new β-sitosterol derivative () along with six known ones including; lupeol (), two long-chain fatty alcohols namely undecyl alcohol () and lauryl alcohol (); two long-chain fatty acids namely; myristic acid () and nervonic acid () as well as a glycosidic steroidal alkaloid; (25R)-3β--α-L-rhamnopyranosyl-(1→2)--[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranosyloxy-22α-N-spirosol-5-ene () from the MeOH extracts. A new furan diglycoside, (2,5-D-diglucopyranosyloxy-furan) () was also characterized from the CHCl/MeOH extract of stem bark of . The structures of the compounds were determined on the basis of spectroscopic evidence and comparison with literature data. Compounds , and isolated in sufficient yields were tested against the growth of two subsp. (), two (), and one () using broth dilution methods, while the minimum inhibitory concentration (MIC) was determined by serial dilution. The inhibition of growth was determined by the use of both flow cytometry (FCM) and color change units (CCU) methods. Compounds and showed moderate activity against the growth of and but were inactive against the growth of . The lowest MIC value was 50 μg/ml for compound against . The rest of the compounds showed minimal or no activity against the strains of tested. This is the first report on the use of combined FCM and CCU to determine inhibition of growth of . The activity of these compounds against other bacterial strains should be tested and their safety profiles determined.
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http://dx.doi.org/10.3389/fphar.2017.00920DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5742823PMC
December 2017

Immunization of mice with soluble lysate of interferon gamma expressing ANKA induces high IFN-γ production.

Trop Dis Travel Med Vaccines 2017 6;3:11. Epub 2017 Jun 6.

Department of Tropical and Infectious Diseases, Institute of Primate Research (IPR), P.O. Box 24481-00502, Karen, Nairobi, Kenya.

Background: Efforts in search of lasting malaria vaccine have led to the development of transgenic rodent malaria parasites. As a result, wild type ANKA (WTPbA) has recently been transformed to express mouse interferon gamma (mIFN-γ). The immunomodulatory effect of this transgenic parasite on WTPbA infection has been demonstrated. However, the protective immune responses after repeated immunization with soluble lysate of this parasite has not been investigated.

Methods: Soluble lysate of transgenic PbA (TPbA) was prepared and concentration of IFN-γ in lysate determined by ELISA. Four groups of 20 BALB/c mice each (two treatment groups and two control groups) were setup. Treatment Groups 1 and 2 were primed (at day 0) with lysate of TPbA containing 75 pg/ml IFN-γ and live TPbA parasites respectively. Infection in Group 2 mice was cured with Coartem™ at 450 mg/kg for 3 days. At day 14 post-priming, both groups were boosted twice at day 14 and day 28 with lysate of TPbA containing 75 pg/ml IFN-γ and 35 pg/ml IFN-γ respectively. Blood and spleen samples were collected at day 0, day 14, day 21 and day 28 for preparation of serum and cell cultures respectively. Serum IgG and cytokines (TNF-α and IFN-γ) levels in culture supernatant were measred by ELISA.Survivorship and parasitemia were daily monitored for 21 days. Data were statistically analyzed using ANOVA student's test. A value of <0.05 was considered significant.

Results: At day 28 post-priming, IFN-γ production in Group 1 was tenfold higher than in RBC control group ( = 0.070) There was significant difference in IFN-γ production among the groups at day 28 ( < 0.0001). TNF-α production in Group 1 mice increased fourfold in Group 2 mice from day 14 to day 28 post-immunization ( = 0.0005). There was no significant effect on serum IgG production. Mice in treatment groups survived 5 to 4 days longer compared to non-immunized group.

Conclusion: The study has demonstrated that, repeated immunization with soluble lysate of TPbA induces Th 1 response leading to increased IFN-γ and TNF-γ production.
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http://dx.doi.org/10.1186/s40794-017-0053-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5531070PMC
June 2017

Development of Neurological Mouse Model for Toxoplasmosis Using Isolated from Chicken in Kenya.

Patholog Res Int 2017 24;2017:4302459. Epub 2017 May 24.

Department of Public Health, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00200, Nairobi, Kenya.

Animal models for the toxoplasmosis are scarce and have limitations. In this study, a neurological mouse model was developed in BALB/c mice infected intraperitoneally with 15 cysts of a isolate. The mice were monitored for 42 days and euthanized at different time points. Another group of mice were orally treated with dexamethasone (DXM: 2.66 mg/kg daily, 5.32 mg/kg daily) at 42 days after infection and monitored for a further 42 days. A mortality rate of 15% and 28.6% was observed in mice given 2.66 mg/kg/day and 5.32 mg/kg/day of DXM, respectively. The mean cyst numbers in the brain of DXM treated mice increased up to twofold compared with chronically infected untreated mice. Infections up to 42 days were associated with an increase in both IgM and IgG levels but following dexamethasone treatment, IgM levels declined but IgG levels continued on rising. The brain of toxoplasmosis infected mice showed mononuclear cellular infiltrations, neuronal necrosis, and cuffing. The severity of pathology was higher in mice treated with dexamethasone compared to the positive control groups. The findings of this study demonstrate that DXM-induced reactivation of chronic toxoplasmosis may be a useful development of laboratory animal model in outbred mice used for studies.
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http://dx.doi.org/10.1155/2017/4302459DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5463144PMC
May 2017

Prevalence of Hepatitis C Virus Infection and Its Risk Factors among Patients Attending Rwanda Military Hospital, Rwanda.

Biomed Res Int 2017 26;2017:5841272. Epub 2017 Jan 26.

Department of Molecular Biology and Biotechnology, Institute of Basic Sciences, Technology and Innovation (PAUISTI), Pan African University, P.O. Box 6200-00200, Nairobi, Kenya; Department of Biochemistry, School of Biomedical Sciences, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000-00200, Nairobi, Kenya.

In Rwanda, the prevalence of viral hepatitis (HCV) is poorly understood. The current study investigated the prevalence and risk factors of HCV infection in Rwanda. A total of 324 patients attending Rwanda Military Hospital were randomly selected and a questionnaire was administered to determine the risk factors. Blood was collected and screened for anti-HCV antibodies and seropositive samples were subjected to polymerase chain reaction method. Hematology abnormalities in the HCV infected patients were also investigated. Anti-HCV antibody and active HCV infection were found in 16.0% and 9.6% of total participants, respectively. Prevalence was highest (28.4%; 19/67) among participants above 55 years and least (2.4%; 3/123) among younger participants (18-35 years). There was a significant ( = 0.031) relationship between place of residence and HCV infection with residents of Southern Province having significantly higher prevalence. The hematological abnormalities observed in the HCV infected patients included leukopenia (48.4%; 15/52), neutropenia (6.5%; 2/52), and thrombocytopenia (25.8%; 8/52). The HCV infection was significantly higher in the older population (>55 years) and exposure to injection from traditional practitioners was identified as a significant ( = 0.036) risk factor of infection. Further studies to determine the factors causing the high prevalence of HCV in Rwanda are recommended.
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http://dx.doi.org/10.1155/2017/5841272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5299157PMC
March 2017

IgM, lgG and IL-6 profiles in the Trypanosoma brucei brucei monkey model of human African trypanosomiasis.

Acta Trop 2017 Apr 15;168:45-49. Epub 2017 Jan 15.

Jomo Kenyatta University of Agriculture and Technology, College of Agriculture and Natural Resources, Animal Sciences Department, P.O. Box 62000-00200, Nairobi, Kenya. Electronic address:

Human African trypanosomiasis (HAT) patients manifest immunological profiles, whose variations over time can be used to indicate disease progression. However, monitoring of these biomarkers in human patients is beset by several limitations which can be offset by using chronic animal models. A recent improved monkey model of HAT using a Trypanosoma brucei brucei isolate has been developed but the immunological profile has not been elucidated. The objectives of the current study was to determine the IgM, IgG and IL-6 profiles in blood and cerebrospinal fluid (CSF) in vervet monkeys infected with T. b. brucei. Three vervet monkeys were infected intravenously with 10T. b. brucei, monitored for disease development and subsequently treated 28days post infection (dpi) sub-curatively using diminazene aceturate (DA) to induce late stage disease and curatively treated with melarsoprol (Mel B) at 119 dpi, respectively. Matched serum and cerebrospinal fluid (CSF) samples were obtained at regular intervals and immunospecific IgM, immunoglobulin G (IgG) were quantified by ELISA while IL-6 was assayed using a cytometric bead array (CBA) kit. Results showed that following infection, CSF IgM, IgG, IL-6 and serum IL-6 were significantly (p<0.05) elevated with peak levels coinciding with relapse parasitaemia. The IgG levels increased to reach OD peak levels of 0.442±0.5 at 126 dpi. After curative treatment with MelB, the serum IgM and Ig G levels fell rapidly to attain pre-infection levels within 35 and 49days, respectively. This shows that the profile of these immunoglobulins can be used as an indicator of curative treatment. CSF IL-6 concentrations of infected vervet monkeys showed no significant change (P>0.05) between infection and 35 dpi but levels increased significantly (P<0.05) with the highest level of 55.53pg/ml recorded at112 dpi. IL-6 elevation from 35 dpi may be indicative of parasite neuroinvasion hence can be used as possible candidate marker for late stage disease in the monkey model. Further, the marker can also be used in conjunction with IgG and IgM as markers for development of test of cure for HAT.
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http://dx.doi.org/10.1016/j.actatropica.2017.01.012DOI Listing
April 2017

Detection of Natural Infection in Chicken in Thika Region of Kenya Using Nested Polymerase Chain Reaction.

Biomed Res Int 2016 17;2016:7589278. Epub 2016 Nov 17.

Department of Biochemistry, JKUAT, P.O. Box 62000, Nairobi 00200, Kenya.

The detection of in free-range chickens is a good indicator of possible risk to human beings. The aim of this study was to investigate the occurrence of in free-range chicken using polymerase chain reaction (PCR). Brain samples from 105 free-range chickens from three administrative areas in Thika region, Kenya, were collected, DNA-extracted, and analyzed using PCR to detect presence of . The overall prevalence of in all the three areas was 79.0% (95% CI: 70.0-86.4%) and the prevalence across the three areas was not significantly different ( = 0.5088; = 1.354). Female chickens had higher (79.4%) prevalence than males (78.6%), although the difference was not significant ( = 0.922, = 0.01). However, chickens that were more than 2 years old had significantly ( = 0.003; = 11.87) higher prevalence compared to younger ones. The study indicates that there was a high occurrence of infection in free-range chickens from Thika region and that the infection rate is age dependent. Further studies should be carried out to determine the possible role of roaming chickens in the epidemiology of the disease among humans in the area.
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http://dx.doi.org/10.1155/2016/7589278DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5131234PMC
February 2017

Selected ethno-medicinal plants from Kenya with in vitro activity against major African livestock pathogens belonging to the "Mycoplasma mycoides cluster".

J Ethnopharmacol 2016 Nov 17;192:524-534. Epub 2016 Sep 17.

Biosciences Eastern & Central Africa - International Livestock Research Institute, Old Naivasha Road, PO Box 30709, 00100 Nairobi, Kenya. Electronic address:

Ethnopharmocological Relevance: Members of 'Mycoplasma mycoides cluster' are important ruminant pathogens in Africa. Diseases caused by these Mycoplasma negatively affect the agricultural sector especially in developing countries through losses in livestock productivity, mortality and international trade restrictions. There is therefore urgent need to develop antimicrobials from alternative sources such as medicinal plants to curb these diseases. In Kenya, smallholder farmers belonging to the Maasai, Kuria and Luo rely on traditional Kenyan herbals to treat respiratory symptoms in ruminants. In the current study extracts from some of these plants were tested against the growth of members of Mycoplasma mycoides cluster.

Aim: This study aimed at identifying plants that exhibit antimycoplasmal activities using an ethnobotanical approach.

Materials And Methods: Kenyan farmers of Maasai, Luo and Kuria ethnic groups were interviewed for plant remedies given to livestock with respiratory syndromes. The plant materials were thereafter collected and crude extracts prepared using a mixture of 50% of methanol (MeOH) in dichloromethane (CHCl), neat methanol (MeOH), ethanol (EtOH) and water to yield four crude extracts per plant part. The extracts were tested in vitro against five strains of Mycoplasma mycoides subsp. capri, five strains of Mycoplasma mycoides subsp. mycoides and one strain of Mycoplasma capricolum subsp capricolum using broth micro-dilution assays with an initial concentration of 1mg/ml. Minimum inhibitory concentration (MIC) of the most active extracts were determined by serial dilution.

Results: Extracts from five plants namely: Solanum aculeastrum, Albizia coriaria, Ekebergia capensis, Piliostigma thonningii and Euclea divinorum exhibited the highest activities against the Mycoplasma strains tested. Mycoplasma mycoides subsp. mycoides were more susceptible to these extracts than Mycoplasma mycoides subsp. capri and Mycoplasma capricolum susp. capricolum. The activities of the crude extracts varied with the solvent used for extraction. The MICs mean values of the active extracts varied from 0.02 to 0.6mg/ml.

Conclusions: The results suggested that these plants could potentially contain antimicrobial compounds that might be useful for the treatment of respiratory diseases in ruminants. Future work should focus on the isolation and identification of the active compounds from the plant extracts that showed interesting activities and evaluation of their antimicrobial and cytotoxic potential.
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http://dx.doi.org/10.1016/j.jep.2016.09.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5081062PMC
November 2016

Loop Mediated Isothermal Amplification for Detection of Trypanosoma brucei gambiense in Urine and Saliva Samples in Nonhuman Primate Model.

Biomed Res Int 2015 4;2015:867846. Epub 2015 Oct 4.

Biochemistry Department, College of Health Sciences, Jomo Kenyatta University of Agriculture and Technology (JKUAT), P.O. Box 62000, Nairobi 00200, Kenya.

Human African trypanosomiasis (HAT) is a vector-borne parasitic zoonotic disease. The disease caused by Trypanosoma brucei gambiense is the most prevalent in Africa. Early diagnosis is hampered by lack of sensitive diagnostic techniques. This study explored the potential of loop mediated isothermal amplification (LAMP) and polymerase chain reaction (PCR) in the detection of T. b. gambiense infection in a vervet monkey HAT model. Six vervet monkeys were experimentally infected with T. b. gambiense IL3253 and monitored for 180 days after infection. Parasitaemia was scored daily. Blood, cerebrospinal fluid (CSF), saliva, and urine samples were collected weekly. PCR and LAMP were performed on serum, CSF, saliva, and urine samples. The detection by LAMP was significantly higher than that of parasitological methods and PCR in all the samples. The performance of LAMP varied between the samples and was better in serum followed by saliva and then urine samples. In the saliva samples, LAMP had 100% detection between 21 and 77 dpi, whereas in urine the detection it was slightly lower, but there was over 80% detection between 28 and 91 dpi. However, LAMP could not detect trypanosomes in either saliva or urine after 140 and 126 dpi, respectively. The findings of this study emphasize the importance of LAMP in diagnosis of HAT using saliva and urine samples.
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http://dx.doi.org/10.1155/2015/867846DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4609394PMC
August 2016

Parasite accumulation in placenta of non-immune baboons during Plasmodium knowlesi infection.

Malar J 2015 Mar 18;14:118. Epub 2015 Mar 18.

Department of Tropical and Infectious Diseases, Institute of Primate Research, PO Box 24481-00502, Karen, Nairobi, Kenya.

Background: Placental malaria (PM) causes adverse pregnancy outcomes in the mother and her foetus. It is difficult to study PM directly in humans due to ethical challenges. This study set out to bridge this gap by determining the outcome of PM in non-immune baboons in order to develop a non-human primate model for the disease.

Methods: Ten pregnant baboons were acquired late in their third trimester (day 150) and randomly grouped as seven infected and three non-infected. Another group of four nulligravidae (non-pregnant) infected was also included in the analysis of clinical outcome. Malaria infection was intravenously initiated by Plasmodium knowlesi blood-stage parasites through the femoral vein on 160(th) day of gestation (for pregnant baboons). Peripheral smear, placental smear, haematological samples, and histological samples were collected during the study period. Median values of clinical and haematological changes were analysed using Kruskal-Wallis and Dunn's Multiple Comparison Test. Parasitaemia profiles were analysed using Mann Whitney U test. A Spearman's rank correlation was run to determine the relationship between the different variables of severity scores. Probability values of P <0.05 were considered significant.

Results: Levels of white blood cells increased significantly in pregnant infected (34%) than in nulligravidae infected baboons (8%). Placental parasitaemia levels was on average 19-fold higher than peripheral parasitaemia in the same animal. Infiltration of parasitized erythrocytes and inflammatory cells were also observed in baboon placenta. Malaria parasite score increased with increase in total placental damage score (rs = 0.7650, P <0.05) and inflammatory score (rs = 0.8590, P <0.05). Although the sample size was small, absence of parasitized erythrocytes in cord blood and foetal placental region suggested lack of congenital malaria in non-immune baboons.

Conclusion: This study has demonstrated accumulation of parasitized red blood cells and infiltration of inflammatory cells in the placental intravillous space (IVS) of baboons that are non-immune to malaria. This is a key feature of placental falciparum malaria in humans. This presents the baboon as a new model for the characterization of malaria during pregnancy.
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http://dx.doi.org/10.1186/s12936-015-0631-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4372046PMC
March 2015

Development of a safer laboratory vervet monkey model for the study of human African trypanosomiasis.

Afr J Lab Med 2014 29;3(1):100. Epub 2014 Oct 29.

Department of Land Resources Planning Management, Jomo Kenyatta University of Agriculture and Technology, Kenya.

Background: There are three subspecies of : and . The first two are infectious to humans, whilst is not. Identifying an animal model of that mimics human African trypanosomiasis (HAT) would enable researchers to study HAT without subjecting themselves to undue risks such as accidental infection.

Objectives: This study assessed the sequential clinical, parasitological and haematological changes in vervet monkeys infected with .

Methods: Three vervet monkeys were infected with a 10 inoculum of (isolate GUTat 1). Late-stage disease was induced by subcurative treatment with diminazene aceturate 28 days post-infection. The animals were treated curatively with melarsoprol upon relapse. Parasitaemia and clinical signs were monitored daily and, at weekly intervals, the monkeys' blood and cerebrospinal fluid (CSF) were sampled for haematology and parasitosis assessments, respectively.

Results: The first-peak parasitaemia was observed between seven and nine days post-infection. Clinical signs associated with the disease included fever, dullness, pallor of mucous membranes, lymphadenopathy, splenomegaly and oedema. Late-stage signs included stiffness of joints and lethargy. The monkeys developed a disease associated with microcytic hypochromic anaemia. There was an initial decline, followed by an increase, in total white blood cell counts from early- to late-stage disease. Trypanosomes were detected in the CSF and there was a significant increase in white cell counts in the CSF during late-stage disease. Infected vervet monkeys displayed classical clinical symptoms, parasitological and haematological trends that were similar to monkeys infected with .

Conclusion: The vervet monkey model can be used for studying HAT without putting laboratory technicians and researchers at high risk of accidental infection.
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http://dx.doi.org/10.4102/ajlm.v3i1.100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5637759PMC
October 2014

Questionnaire survey on the occurrence of risk factors for Toxoplasma gondii infection amongst farmers in Thika District, Kenya.

J S Afr Vet Assoc 2013 Apr 18;84(1):E1-6. Epub 2013 Apr 18.

Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenia.

A survey was conducted to determine the occurrence of risk factors for Toxoplasma gondii infection amongst farmers in Thika District, Kenya. Interviews were conducted in a total of 385 households using a structured questionnaire. The water consumed at household level originated from taps (74.3%), rivers or streams (15.1%), wells (5.4%) and boreholes (5.2%). A number of households (46.8%) consumed water without boiling or applying any form of treatment. All respondents washed vegetables before cooking, whilst 99.0% washed fruits before eating. Boiled milk was preferred by 99.5% of the farmers. The majority (85.2%) consumed beef more often, whilst 1.6% consumed pork. The majority (98.7%) consumed thoroughly cooked meat. Meat was preserved by 17% of farmers. Only four farmers (1.2%) who practised mixed farming used gloves when handling livestock manure. Five farmers (1.6%) reported the occurrence of abortion in ruminants and pigs on their farms within the last two years before the study. Almost half (44.9%) of the households owned cats, which were kept mainly as pets (79.8%) and for deterring rodents (20.2%). The majority of households (91.3%) fed the cats on leftovers, whilst 8.1% fed cats with raw offal. Sixteen households (9.2%) provided housing for cats. Only five households (2.8%) had litter boxes, but none of the households with litter boxes used gloves when cleaning them out. Disposal of cat faeces was done mainly by women (55.5%). Only one farmer (0.3%) had some knowledge about toxoplasmosis, but was not aware of the transmission mechanism. The study highlights the need for public health education to raise awareness of risk factors for toxoplasmosis.
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http://dx.doi.org/10.4102/jsava.v84i1.191DOI Listing
April 2013

Influence of trypanocidal therapy on the haematology of vervet monkeys experimentally infected with Trypanosoma brucei rhodesiense.

Acta Trop 2011 Jul 21;119(1):14-8. Epub 2011 Mar 21.

Institute of Primate Research, Nairobi, Kenya.

The aim of this study was to characterise the sequential haematological changes in vervet monkeys infected with Trypanosoma brucei rhodesiense and subsequently treated with sub-curative diminazene aceturate (DA) and curative melarsoprol (MelB) trypanocidal drugs. Fourteen vervet monkeys, on a serial timed-kill pathogenesis study, were infected intravenously with 10(4) trypanosomes of a stabilate T. b. rhodesiense KETRI 2537. They were treated with DA at 28 days post infection (dpi) and with MelB following relapse of infection at 140 dpi. Blood samples were obtained from the monkeys weekly, and haematology conducted using a haematological analyser. All the monkeys developed a disease associated with macrocytic hypochromic anaemia characterised by a reduction in erythrocytes (RBC), haemoglobin (HB), haematocrit (HCT), mean cell volume (MCV), platelet count (PLT), and an increase in the red cell distribution width (RDW) and mean platelet volume (MPV). The clinical disease was characteristic of human African trypanosomiasis (HAT) with a pre-patent period of 3 days. Treatment with DA cleared trypanosomes from both the blood and cerebrospinal fluid (CSF). The parasites relapsed first in the CSF and later in the blood. This treatment normalised the RBC, HCT, HB, PLT, MCV, and MPV achieving the pre-infection values within two weeks while RDW took up to 6 weeks to attain pre-infection levels after treatment. Most of the parameters were later characterised by fluctuations, and declined at one to two weeks before relapse of trypanosomes in the haemolymphatic circulation. Following MelB treatment at 140 dpi, most values recovered within two weeks and stabilised at pre-infection levels, during the 223 days post treatment monitoring period. It is concluded that DA and MelB treatments cause similar normalising changes in the haematological profiles of monkeys infected with T. b. rhodesiense, indicating the efficacy of the drugs. The infection related changes in haematology parameters, further characterise the vervet monkey as an optimal induced animal model of HAT. Serial monitoring of these parameters can be used as an adjunct in the diagnosis and prognosis of the disease outcome in the vervet monkey model.
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http://dx.doi.org/10.1016/j.actatropica.2011.02.013DOI Listing
July 2011

Genotypic and phenotypic characterization of Trypanosoma brucei gambiense isolates from Ibba, South Sudan, an area of high melarsoprol treatment failure rate.

Acta Trop 2007 Nov-Dec;104(2-3):84-90. Epub 2007 Aug 1.

Trypanosomiasis Research Institute (TRC), PO Box 362, Kikuyu, Kenya.

Resistance of trypanosomes to melarsoprol is ascribed to reduced uptake of the drug via the P2 nucleoside transporter. The aim of this study was to look for evidence of drug resistance in Trypanosoma brucei gambiense isolates from sleeping sickness patients in Ibba, South Sudan, an area of high melarsoprol failure rate. Eighteen T. b. gambiense stocks were phenotypically and only 10 strains genotypically characterized. In vitro, all isolates were sensitive to melarsoprol, melarsen oxide, and diminazene. Infected mice were cured with a 4 day treatment of 2.5mg/kg bwt melarsoprol, confirming that the isolates were sensitive. The gene that codes for the P2 transporter, TbATI, was amplified by PCR and sequenced. The sequences were almost identical to the TbAT1(sensitive) reference, except for one point mutation, C1384T resulting in the amino acid change proline-462 to serine. None of the described TbAT1(resistant)-type mutations were detected. In a T. b. gambiense sleeping sickness focus where melarsoprol had to be abandoned due to the high incidence of treatment failures, no evidence for drug resistant trypanosomes or for TbAT1(resistant)-type alleles of the P2 transporter could be found. These findings indicate that factors other than drug resistance contribute to melarsoprol treatment failures.
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http://dx.doi.org/10.1016/j.actatropica.2007.07.007DOI Listing
February 2008

Isolation and propagation of Trypanosoma brucei gambiense from sleeping sickness patients in south Sudan.

Trans R Soc Trop Med Hyg 2007 Jun 1;101(6):540-6. Epub 2007 Feb 1.

Trypanosomiasis Research Centre (TRC) of KARI, PO Box 362, Kikuyu, Kenya.

This study aimed at isolating Trypanosoma brucei gambiense from human African trypanosomiasis (HAT) patients from south Sudan. Fifty HAT patients identified during active screening surveys were recruited, most of whom (49/50) were in second-stage disease. Blood and cerebrospinal fluid samples collected from the patients were cryopreserved using Triladyl as the cryomedium. The samples were stored at -150 degrees C in liquid nitrogen vapour in a dry shipper. Eighteen patient stabilates could be propagated in immunosuppressed Mastomys natalensis and/or SCID mice. Parasitaemia was highest in SCID mice. Further subpassages in M. natalensis increased the virulence of the trypanosomes and all 18 isolates recovered from M. natalensis or SCID mice became infective to other immunosuppressed mouse breeds. A comparison of immunosuppressed M. natalensis and Swiss White, C57/BL and BALB/c mice demonstrated that all rodent breeds were susceptible after the second subpassage and developed a parasitaemia >10(6)/ml by Day 5 post infection. The highest parasitaemias were achieved in C57/BL and BALB/c mice. These results indicate that propagation of T. b. gambiense isolates after initial isolation in immunosuppressed M. natalensis or SCID mice can be done in a range of immunosuppressed rodents.
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http://dx.doi.org/10.1016/j.trstmh.2006.11.008DOI Listing
June 2007

IL-10 is up regulated in early and transitional stages in vervet monkeys experimentally infected with Trypanosoma brucei rhodesiense.

Parasitol Int 2006 Dec 8;55(4):243-8. Epub 2006 Aug 8.

KARI-Trypanosomiasis Research Centre, Kikuyu, Kenya.

IL-10 has been suggested as a possible parameter for human African trypanosomiasis stage determination. However, conclusive experimental studies have not been carried out to evaluate this, which is a prerequisite before a potential test can be validated in humans for diagnostic purposes. We used the vervet monkey model of trypanosomiasis to scrutinize IL-10 in blood and cerebrospinal fluid (CSF). Five adult males were experimentally infected with T. b. rhodesiense. The infected animals became anemic and exhibited weight loss. Parasitemia was patent after 3 days and fluctuated around 3.7 x 10(7) trypanosomes/ml throughout the experimental period. The total CSF white cell counts increased from pre-infection means around 3 cells/micro l to a peak of 30 cells/micro l, 42 days post-infection (DPI). IL-10 was not detectable (<2 pg/ml) in serum prior to infection. IL-10 serum concentrations increased to 273 pg/ml 10 DPI coinciding with the first peak of parasitemia. Thereafter the levels declined to a mean value of 77 pg/ml 34 DPI followed by a significant rise to a second peak of 304 pg/ml (p<0.008) 42 DPI. There was no detectable IL-10 in CSF. IL-10 synthesis is thus stimulated both in the early and transitional stages of experimental trypanosomiasis. That IL-10 is produced in early stage disease is an interesting finding unlikely to be detected in humans where it is difficult to determine the exact time of infection. The IL-10 peak observed on day 42 of infection might indicate onset of parasite neuroinvasion coinciding with a peak in white blood cell counts in the blood and CSF.
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http://dx.doi.org/10.1016/j.parint.2006.06.004DOI Listing
December 2006

Cryopreservation of Trypanosoma brucei gambiense in a commercial cryomedium developed for bull semen.

Acta Trop 2006 Jul 27;98(3):207-11. Epub 2006 Jun 27.

Trypanosomiasis Research Institute (TRC), P.O. Box 362, Kikuyu, Kenya.

There have been major advances in the formulation of cryomedia for spermatozoa owing to their economic importance. In this study, the suitability of the commercial cryomedium Triladyl developed for bull semen was evaluated for the cryopreservation of Trypanosoma brucei gambiense. Cryopreservation efficacy was determined by direct counting of motile trypanosomes and by viability assessment using in vitro and in vivo methods. Culture medium containing 10% glycerol was used as the control. Trypanosomes cryopreserved in Triladyl demonstrated a higher in vitro viability than those in culture medium with 10% glycerol. Similar results were obtained in vivo in immunosuppressed Mastomys natalensis. Trypanosomes cryopreserved in Triladyl showed better growth characteristics than those in culture medium with glycerol. It can be concluded that the use of Triladyl in the cryopreservation of T. b. gambiense leads to a better survival of the trypanosomes which could lead to an improved isolation of T. b. gambiense from sleeping sickness patients.
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http://dx.doi.org/10.1016/j.actatropica.2005.11.011DOI Listing
July 2006

Proinflammatory cytokine expression in the early phase of Trypanosoma brucei rhodesiense infection in vervet monkeys (Cercopithecus aethiops).

Infect Immun 2004 May;72(5):3063-5

Primate Division, Kenya Trypanosomiasis Research Institute, Kikuyu, Kenya. Department of Zoology, University of Aberdeen, Aberdeen AB29 2TZ, Scotland, United Kingdom.

A vervet monkey model of trypanosomiasis was used to study inflammatory cytokine responses in serum and cerebrospinal fluid (CSF). Gamma interferon levels were transiently up-regulated in serum between days 6 and 8 of infection, followed by a sustained up-regulation of tumor necrosis factor alpha (TNF-alpha) and soluble TNF receptor 1. At no time were these cytokines detectable in the CSF.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC387871PMC
http://dx.doi.org/10.1128/IAI.72.5.3063-3065.2004DOI Listing
May 2004
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