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Genotypic Characterization of Resistance to Neuraminidase Inhibitors amongst Influenza A viruses that circulated in Kenya from 2008 to 2011
No full textBackground: Vaccines and antivirals are the mainstay for mitigation and clinical management of influenza infections. However, due to the ever changing antigenic profile, vaccine formulations are revised every year to keep them efficacious. Neuraminidase (NA) inhibitors, mainly oseltamivir and zanamivir, function both as prophylactic and treatment agents. In neuraminidase inhibition, inhibitor molecules mimic NA’s natural substrate and bind to the active site, preventing NA from cleaving host cell receptors and releasing new virus. Currently there exists no data on antiviral susceptibility profile of influenza A isolates circulating within the Eastern African region. Here we characterized the antiviral susceptibility of the 2008-2011 influenza A viruses circulating in Kenya. Methodology: Nasopharyngeal swab specimen from consenting outpatients of ages greater than or equal to two months were obtained and transported under the cold chain to the National Influenza Center (NIC) and screened by real-time RT-PCR using primers targeted at the matrix, and hemagglutinin genes of influenza A subtypes. Positive specimens were inoculated onto MDCK monolayers to isolate virus. RNA was extracted from virus isolates followed by PCR amplification of NA gene segments using gene-specific primers. Nucleotide sequencing of the NA amplicons was carried out using the BigDye chemistry prior to analyses using a suite of bioinformatics tools. Results: 836 influenza A viruses were isolated. 108 (13%) isolates were analyzed for susceptibility to NA inhibitors. 64% (7/11) of the 2008 seasonal influenza A/H1N1 isolates depicted oseltamivir resistant marker H275Y while all 33 influenza A/H3N2 isolates had H at position 275 hence were sensitive to oseltamivir. Similarly, genetic analysis of the A(H1N1)pdm09 strains in 2009 showed that all had H275 hence sensitive to oseltamivir. The same pattern was duplicated in 2 of the pandemic influenza A/ H1N1 isolates analyzed in the year 2010. Thus all A(H1N1)pdm09 isolated were sensitive to oseltamivir. In 2011 we isolated 14 isolates belonging to influenza A/H3N2 subtype. All these had H 275 in the NA protein implying sensitivity to oseltamivir. Overall, our genotypic data demonstrate that there was oseltamivir resistance in seasonal influenza A (H1N1) viruses isolated in Kenya in 2008-2009. Conclusion: Our study shows that seasonal influenza A/H1N1 was displaced in 2010 and 2011 after introduction influenza A(H1N1)pdm09 which has since replaced the previous seasonal influenza A/H1N1
Molecular characterization of human parainfluenza virus type 1 in infants attending Mbagathi District Hospital, Nairobi, Kenya
No full textBackground. Human parainfluenza virus type 1 (HPIV-1), a Paramyxovirus, is a leading cause of paediatric respiratory hospitalizations globally. Currently, there is no HPIV-1 vaccine. Hence, there is need to characterize circulating strains of this virus to establish the feasibility of developing a vaccine against the virus. The variable HPIV-1 Hemagglutin-neuraminidase (HN) protein is found in the envelope of HPIV-1 where it initiates the infection process by binding to cellular receptors. HN is also the major antigen against which the human immune response is directed against. The present study focused on identifying mutations in the HN gene that would be useful in understanding evolution of HPIV-1. Methods. 21 HPIV-1 isolates were obtained after screening nasopharyngeal samples from patients with influenza-like-illness. The samples were collected from Mbagathi District Hospital Nairobi from the period June 2006- December 2010. RT-PCR was carried out on the isolates using HN-specific primers to amplify a 360nt in the most polymorphic region and the amplicons sequenced. Genomic data was analysed using a suite of bioinformatic software. Results. Forty-eight polymorphic sites with a total of 55 mutations were identified at the nucleotide level and 47 mutations at 23 positions at the amino acid level. There was more radical non-synonymous amino acid changes (7 positions) observed than conservative non-synonymous changes (1 position) on the HN gene fragment. No positively selected sites were found in the HN protein. Conclusion
Molecular Characterization of Human Enterovirus 68 Strains Circulating in Kenya between 2008 and 2010
No full textBackground: Human enterovirus 68 (HEV-68) is a rarely detected viral pathogen associated with acute respiratory illness. It is unique among enteroviruses because it shares common biological properties with human rhinoviruses. In 2008-2010, an upsurge of acute respiratory illnesses associated with HEV-68 were reported in many parts of the world including Asia, Europe and the United States. Activity of human respiratory enterovirus infections have not been well characterized in the region including Kenya Objective: To molecularly characterize HEV-68 strains isolated in Kenya between 2008 and 2010, targeting the VP1 gene. Methods: A total of six (6) HEV-68 strains isolated in Kenya from nasopharyngeal specimens were analyzed. Viral RNA was extracted and partial VP1 gene amplified using RT-PCR followed by sequencing. The resulting VP1 sequences were compared to corresponding regions of prototype Fermon strain and other previously characterized EV-68 strains deposited in Genbank. Results: Pair-wise comparison of VP1 sequences of Kenyan EV-68 strains revealed 87.2-99.5% nucleotide identity. The Kenyan viruses shared 86.0-88.4% and 91-99% nucleotide identities with Fermon and recently characterized EV-68 strains reported in Gen Bank respectively. Alignment of partial VP1 sequences of Kenyan isolates with Fermon revealed 12 amino acid substitutions and one deletion in five of the isolates and 11 amino acid substitutions. Phylogenetic analysis showed that five of the Kenyan isolates clustered closely to EV-68 strains that circulated in New York City, USA and Yamagata, Japan. One Kenyan isolate clustered closely to viruses which circulated in Netherlands, Europe. All the Kenyan isolates clustered away from Fermon EV-68 strain indicating divergence from the prototype strain. Conclusions: This study confirms circulation of HEV-68 strains in Kenya during the period 2008 to 2010. Most Kenyan isolates were similar to viruses which circulated in New York City, USA and Yamagata, Japan. The viruses had genetically evolved from Fermon prototype reference strain but remained antigenically similar. Monitoring of evolution patterns of respiratory viruses such as HEV-68 is essential for early prediction of viruses with epidemic potential
Epidemiology and Molecular Characterization of Influenza Viruses Isolated From Children Admitted At the Kenyatta National Hospital in April-July 2008
No full textBackground: 20% of deaths in children are caused by respiratory infections. Acute respiratory infections (ARIs), have both bacterial and viral aetiologies. Influenza viruses cause highly contagious respiratory diseases. In Kenya, three studies focusing on influenza-like-illness and severe acute respiratory illness are ongoing. Despite these surveillance programmes, little is known regarding the epidemiology and molecular characteristics of influenza viruses found in children at the KenyattaNational Hospital (KNH). Objective: To determine the epidemiology and molecular characteristics of influenza viruses from children at the Kenyatta National Hospital during the April-July 2008 period. Methodology: Throat swabs were collected from 388 consenting patients. Swabs were inoculated onto monolayers of cultured MDCK cellsto isolate influenza viruses. The virus isolates were identified by HA/HAI assays. Viral RNA was extracted from isolates followed by RT-PCR amplification of the haemagglutinin gene.Nucleotide sequences were determined by the Sanger dideoxy termination method on an ABI 3500xL genetic analyzer. The nucleotide sequences were aligned to similar sequences from GenBank, and phylogeny inferred using Bayesian methods. Results: Twenty viruses consisting of 19 (95%) influenza B viruses and 1 (5%) seasonal influenza A/H1N1 were detected from the 388 patient samples. HAI titres for both A and B viruses ranged between 320-1280 with both vaccine strains showing a titre of 320. Viruses were detected mostly in 1year olds (11; 55%), patients with LRTI (14; 70%) and in the month of June (9; 45%). The nucleotide sequences displayed had 97-98%similarities to other 2008 influenza sequences. Phylogenetic analyses of seasonal influenza A/H1N1 clustered together with 2008 regional sequences while influenza B also clustered with 2008 sequences. Influenza A sequence showed substitutions at one antigenic site (198-Sb), while 3 antigenic sites (150loop, 160loop and 190 – Helix) on influenza B also had substitutions when compared to the 2008 vaccine strains. Conclusion: In 2008, influenza viruses were common in 1year oldsat KNH. Infection rates were highest in the month of June. Viruses isolated in the study period were genetically similar to those isolated elsewhere. Amino acid changes in the Kenyan isolates did not adversely affect the immunogenicity of the 2008 vaccine
Approaches in Identification of Putative Reservoirs/Hosts of Rift Valley Fever Virus (RVF) in Kenya
No full textBackground: Rift Valley Fever (RVF) is a mosquito borne viral zoonosis, first reported in the Rift Valley of Kenya in 1931. In the last major outbreak of 2006/2007 in Kenya, Baringo, Garissa, and Kilifi districts were major hotspots with mortality of approximately 300 human and 40,000 livestock. Methodology: Blood fed mosquitoes sampled during the outbreak were cryopreserved. Heads and abdomens of single cryopreserved blood fed mosquitoes (n = 213) (Aedes, Culex, Anopheles and Mansonia genera) were screened for RVF virus by cell culture, and RT-PCR. Putative vertebrate hosts of the virus were determined by amplification and sequencing of blood meal cytochrome c oxidase I (COI). The resultant sequences were annotated through a bioinformatic pipeline suite comprising of 1) BioEdit for initial cleaning and development of consensus sequences 2) Basic Local Alignment Search Tool (BLAST) searches against GenBank nr database to identify putative homologues of the sequences and 3) Barcode of Life Data Systems (BOLD) for COI. Results: The results of the in silico analyses implicated 3 species in 2 genera as putative vectors of the virus. Among 12 blood meal samples positive for RVFV 6 were drawn from Garissa samples and implicated goats, human and donkey while the rest were from Baringo and implicated sheep and goats as putative hosts. Conclusion: The analyses demonstrate the potential application of bioinformatics approaches when integrated to wet lab tools as accurate and effective in identification of the vertebrate hosts of RVF, with potential application in public health initiatives in understanding vector borne pathogen epidemiology, and enabling control
MATERNAL IMMUNE RESPONSES AND RISK OF INFANT INFECTION WITH HIV-1 AFTER A SHORT COURSE ZIDOVUDINE IN A COHORT OF HIV-1 INFECTED PREGNANT WOMEN IN RURAL KENYA
No full textABSTRACTObjective: To investigate the effects of short-course nucleoside reverse transcriptaseinhibitor (Zidovudine, ZDW/AZT) on maternal immune responses and risk of infantinfection with HIV-1 among rural-based mothers in western Kenya.Design: A prospective cohort study involving HIV-1 seropositive pregnant mothers andtheir infants.Subjects: One hundred and seven HIV-1 seropositive asymptomatic pregnant womenand their infants.Methods: After informed consent, the women were enrolled at gestation age between16-24 weeks. For cultural and economic reasons, all mothers were allowed to breastfeed their infants. Short-course antepartum regime of AZT was administered to allmothers starting at 36 weeks gestation until start of labour. Maternal absolute CD4+T cell subset assays were performed before 3rd trimester (about 36 weeks gestation)and after a 4-week therapy of AZT (at least one month post-nuptially). Infant HIV-1 status was determined by HIV-1 DNA polymerase chain reaction (PCR) on samplessequentially taken at 1, 2, 3, 4, 6 and 9 months and confirmed by serology at 18 monthsof age.Interventions: Antepartum short-course orally administered AZT: 300mg twice-dailystarting at 36 weeks gestation until start of labour, 300mg at labour onset and 300mgevery three hours during labour until delivery.Main Outcome Measures: Maternal CD4+ T cell counts before and after AZT treatment.Determination of infant HIV-1 infection status.Results: Among 107 women sampled, only 59 received full dose of AZT and thus qualifiedfor present analysis. Of these, 12 infected their children with HIV, while 47 did not.Comparison of CD4+ T cells before and after AZT treatment scored a significant risein all mothers (P = 0.01). This increase in CD4+ T cells was not significant amongmothers who infected their infants with HIV-1 (P = 0.474). However, a significant risein CD4+ T cells following AZT therapy was observed only in mothers who did nottransmit HIV-1 to their infants (P=0.014).Conclusion: These data suggest that a rise in the CD4+ T cell counts following shortAZT regimen, now widely in use in resource-weak countries, may be evidence of theactive suppression of the replication of HIV. However, further studies to examine themulti-factorial effect of CD4+ lymphocytes and pregnancy on MTCT of HIV need tobe carried out to help fully explain the effect of AZT on immune response and whetherthe CD4+T cell count can be used as a true test of immunological normalisation duringantiretroviral therapy
PREVALENCE AND INTENSITY OF URINARY SCHISTOSOMIASIS IN PRIMARY SCHOOL CHILDREN OF THE KOTTO BAROMBI HEALTH AREA, CAMEROON
No full textObjective: To assess the prevalence and intensity of urinary schistosomiasis in school pupilsaged five to sixteen years.Setting: Barombi Kotto Health Area, southwest Cameroon.Design: A cross-sectional study.Subjects: Three hundred and forty seven primary school children.Intervention: All children found to be infected were treated with praziquantel (biltricide).Main outcome measures: The study would be able to provide baseline information on theepidemiology of schistosomiasis which is vital for control strategies.Results: The overall prevalence of Schistosoma haematobium in the study areas was 53.6%,with the highest prevalence of 73.9% recorded in Barombi Kotto village. Children residenton Barombi Kotto island were more significantly infected than those on the peripheralmainland (93.3% versus 46.2%, p < 0.01). Prevalence rate and intensity of infection did notvary significantly (p > 0.05) with sex, class or age of the pupils. The mean egg count variedsignificantly between schools (p < 0.001).Conclusion: Barombi Kotto village was identified as the focus of urinary schistosomiasis,with the highest recorded in children dwelling on the island, the surrounding lake being themain focus of transmission. Focal snail control as an adjunct of chemotherapy and intensivehealth education for the local population are strongly recommended as a means of reducingthe high infection rate in the area
ORTHODONTIC TREATMENT NEEDS AMONG 12-15 YEAR-OLDS IN MOSHI, TANZANIA
No full textABSTRACTObjective: To assess malocclusion and orthodontic treatment needs among 12-15-year-olds in Moshimunicipality, Tanzania.Design: A cross-sectional study.Setting: Moshi municipality, Tanzania.Subjects: Two hundred and eighty nine randomly selected primary school children in Moshimunicipality in the year 2003.Results: Maxillary median diastema occurred in 20.1% of the children. Crowding and spacing inthe incisor segments occurred in 41.2% and 28.4% respectively with significantly more crowdingin males than in females (p = 0.009). Anterior irregularities occurred in 46% of the sample in themaxilla and 51.6% in the mandible. These irregularities were significantly more common in thefemales than in males in the maxilla and mandible (p=0.014, p=0.037 respectively). Reverse overjetwas extremely rare (0.3%). Anterior openbite and antero-posterior molar relation discrepanciesoccurred in 6.2% and 32.5% of the sample, respectively. Crowding, irregularities in the incisorsegments and antero-posterior molar relation discrepancies were dominant malocclusion traitsin this population. The sample mean DAI score was 24.6 points (CI 95% 23.86–25.36). There wasno statistically significant gender difference of DAI scores (p = 0.473). About 65% of the subjectshad either no need or had slight need for treatment whereas 35.3% were found with orthodontictreatment needs ranging from elective (21.5%), highly desirable (6.9%) to mandatory (6.9%).There was no significant gender difference in the categories of treatment need (p = 0.942). Unmetorthodontic treatment needs were present in this population with a very small proportion ofsubjects exhibiting handicapping malocclusion.Conclusion: The information from this study forms part of the basis not only for further research,but also for planning orthodontic care in this community where unmet orthodontic treatmentneeds are present
SUICIDE ATTEMPTS IN A NIGERIAN MILITARY SETTING
No full textObjectives: To describe the characteristics of patients who attempted suicide in a militarysetting and to examine the differences between the suicide attempters and a group of nonsuicide,affective disorder patients.Design: Fifty one consecutive cases of suicide attempts were studied using a questionnairewhich inquired about demographic characteristics and suicide related issues such as methodof attempt used and giving a notice. The suicide attempt group was then compared with acontrol group who had no history of attempted suicide.Setting: Department of Psychiatry, Military Hospital, Yaba, Lagos, Nigeria, which is a 500-bed military general hospital.Subjects: Fifty one attempted suicide patients. Intervention reports on intervention methodsapplied were not within the scope of this report.Main outcome measures: These were also not within the scope of the present study.Results: Suicide attempt patients constituted 0.37% of all admissions during a five-yearperiod, and 60.8% of them were under the age of 30 years. The numbers of male and femalepatients were approximately the same. Depression and acute stress reaction were thecommonest diagnoses. While military dependants most commonly ingested substances intheir suicide attempts, military personnel most often used more violent methods includinghanging and self-stabbing, but none used firearms. Compared with non suicide patients,suicide attempt ones were more likely to be unmarried and to have a family history of mentaldisorder but less likdy to have lost a parent through death before the age of 18 years.Conclusions: The need for a more controlled access to substances capable of being used forself- destruction was highlighted. The need for emergency room doctors to become moreskilful in the identification and assessment of suicide attempt patients was also emphasised
