18 research outputs found

    Randomized controlled field trial to assess the immunogenicity and safety of rift valley fever clone 13 vaccine in livestock

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    BACKGROUND:Although livestock vaccination is effective in preventing Rift Valley fever (RVF) epidemics, there are concerns about safety and effectiveness of the only commercially available RVF Smithburn vaccine. We conducted a randomized controlled field trial to evaluate the immunogenicity and safety of the new RVF Clone 13 vaccine, recently registered in South Africa. METHODS:In a blinded randomized controlled field trial, 404 animals (85 cattle, 168 sheep, and 151 goats) in three farms in Kenya were divided into three groups. Group A included males and non-pregnant females that were randomized and assigned to two groups; one vaccinated with RVF Clone 13 and the other given placebo. Groups B included animals in 1st half of pregnancy, and group C animals in 2nd half of pregnancy, which were also randomized and either vaccinated and given placebo. Animals were monitored for one year and virus antibodies titers assessed on days 14, 28, 56, 183 and 365. RESULTS:In vaccinated goats (N = 72), 72% developed anti-RVF virus IgM antibodies and 97% neutralizing IgG antibodies. In vaccinated sheep (N = 77), 84% developed IgM and 91% neutralizing IgG antibodies. Vaccinated cattle (N = 42) did not develop IgM antibodies but 67% developed neutralizing IgG antibodies. At day 14 post-vaccination, the odds of being seropositive for IgG in the vaccine group was 3.6 (95% CI, 1.5 - 9.2) in cattle, 90.0 (95% CI, 25.1 - 579.2) in goats, and 40.0 (95% CI, 16.5 - 110.5) in sheep. Abortion was observed in one vaccinated goat but histopathologic analysis did not indicate RVF virus infection. There was no evidence of teratogenicity in vaccinated or placebo animals. CONCLUSIONS:The results suggest RVF Clone 13 vaccine is safe to use and has high (>90%) immunogenicity in sheep and goats but moderate (> 65%) immunogenicity in cattle

    Seroprevalence of Infections with Dengue, Rift Valley Fever and Chikungunya Viruses in Kenya, 2007.

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    Arthropod-borne viruses are a major constituent of emerging infectious diseases worldwide, but limited data are available on the prevalence, distribution, and risk factors for transmission in Kenya and East Africa. In this study, we used 1,091 HIV-negative blood specimens from the 2007 Kenya AIDS Indicator Survey (KAIS 2007) to test for the presence of IgG antibodies to dengue virus (DENV), chikungunya virus (CHIKV) and Rift Valley fever virus (RVFV).The KAIS 2007 was a national population-based survey conducted by the Government of Kenya to provide comprehensive information needed to address the HIV/AIDS epidemic. Antibody testing for arboviruses was performed on stored blood specimens from KAIS 2007 through a two-step sandwich IgG ELISA using either commercially available kits or CDC-developed assays. Out of the 1,091 samples tested, 210 (19.2%) were positive for IgG antibodies against at least one of the three arboviruses. DENV was the most common of the three viruses tested (12.5% positive), followed by RVFV and CHIKV (4.5% and 0.97%, respectively). For DENV and RVFV, the participant's province of residence was significantly associated (P≤.01) with seropositivity. Seroprevalence of DENV and RVFV increased with age, while there was no correlation between province of residence/age and seropositivity for CHIKV. Females had twelve times higher odds of exposure to CHIK as opposed to DENV and RVFV where both males and females had the same odds of exposure. Lack of education was significantly associated with a higher odds of previous infection with either DENV or RVFV (p <0.01). These data show that a number of people are at risk of arbovirus infections depending on their geographic location in Kenya and transmission of these pathogens is greater than previously appreciated. This poses a public health risk, especially for DENV

    Prevalence and factors associated with chikungunya virus among persons aged 15–64 years, Kenya, 2007.

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    <p>cut off point to include factors in multivariate is pvalue <0.1</p><p>p value is the global p value for the bivariate variable</p><p>M_OR_CI is the multivariate odds ratio</p><p>M_p_value is the category multivariate p value</p><p>Ref- reference</p><p>+—and above</p><p>N, n = number of persons</p><p>Prevalence and factors associated with chikungunya virus among persons aged 15–64 years, Kenya, 2007.</p

    Prevalence and factors associated with RVF virus among persons aged 15–64 years, Kenya, 2007.

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    <p>cut off point to include factors in multivariate is pvalue <0.1</p><p>p value is the global p value for the bivariate variable</p><p>M_OR_CI is the multivariate odds ratio</p><p>M_p_value is the category multivariate p value</p><p>Ref- reference</p><p>+—and above</p><p>N, n = number of persons</p><p>Prevalence and factors associated with RVF virus among persons aged 15–64 years, Kenya, 2007.</p

    Etiologies of ARI by age group and pathogen, western Kenya. March 1, 2007,-February 28, 2010.

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    <p>All data presented as number and percentage in parentheses rounded to nearest integer.</p>a<p>Case-fatality ratios (CFR) are defined as death in the 30 days following clinic visit for ARI episode.</p>b<p>Denominator for all calculation of percent of positive blood cultures is the number after removing contaminants – coagulase-negative <i>Staphylococcus</i>, <i>Bacillus</i> species, and corynebacterium.</p>c<p>Only 841(25%) ARI patients total had urine collected for urine antigen testing for <i>S. pneumonia</i>, which started on May 21, 2007, and only 805 (24%) ARI patients had both blood culture and urine antigen testing for <i>S. pneumoniae</i> done. For HIV+and HIV−, 112 and 179 ARI patients had urine antigen testing, respectively, and 108 and 175 had both urine antigen and blood culture, respectively.</p>d<p>Other pathogenic bacteria include <i>E. coli, Pseudomonas species, Moraxella catarrhalis,</i> group B <i>Streptococcus, Salmonella typhi</i>.</p>e<p>Rhino/enterovirus and parechovirus were only tested for from January 1, 2009–February 28, 2010. 447 specimens were tested among persons ≥5 years old, of which 334 were from outpatients and 113 from inpatients, 290 among 5–17 year olds, 123 among 18–49 year olds and 34 among those ≥50 years old; 54 among HIV-positive individuals and 90 among HIV-negative persons.</p>f<p>Atypical bacteria were detected by qPCR of np/op specimens. 561 specimens were tested for atypical bacteria. Besides <i>Mycoplasma pneumoniae</i>, the other atypical bacteria tested for were <i>Legionella pneumophila, Legionella</i> other species and <i>Chlamydia pneumoniae</i>. No positives were detected for any of these atypical bacteria.</p

    Incidence rates of ARI for all persons ≥5 years of age, and among HIV-positive and HIV-negative persons ≥18 years from Lwak Hospital, western Kenya. March 1, 2007,-February 28, 2010.

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    <p>Incidence is given as episodes per 100 person-years of observation (pyo).</p>a<p>HIV status was known for 69% of the surveillance population ≥18 years old. Only those with known HIV status were included in the numerators and denominators for rate calculations by HIV status. For persons 5–12 years of age, HIV testing was not routinely done as part of home-based counseling and testing and therefore rates for 5–17 year olds is not included in rate calculations (see methods).</p>b<p>Adjusted clinic rates were calculated by extrapolating from persons with ARI defined at household visit who sought care at another clinic besides the designated referral clinic, Lwak Hospital (see methods). In the age categories 5–17 years, 18–34 years, 35–49 years, ≥50 years, ≥5 years and ≥18 years, the percentage of ARI patients who sought care at another clinic besides Lwak were 41%, 43%, 43%, 48%, 53%, 43%, and 46% respectively. Health-seeking at Lwak was similar among HIV-positive and HIV-negative persons, so the same adjustment percentages were used.</p
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