Resistance to African swine fever virus among African domestic pigs appears to be associated with a distinct polymorphic signature in the RelA gene and upregulation of RelA transcription.

African swine fever virus (ASFV) is a highly contagious and fatal hemorrhagic disease of domestic pigs, which poses a major threat to the swine industry worldwide. Studies have shown that indigenous African pigs tolerate ASFV infection better than European pigs. The porcine v-rel avian reticuloendotheliosis viral oncogene homolog A (RelA) encoding a p65 kD protein, a major subunit of the NF-kB transcription factor, plays important roles in controlling both innate and adaptive immunity during infection with ASFV. In the present study, RelA genes from ASFV-surviving and symptomatic pigs were sequenced and found to contain polymorphisms revealing two discrete RelA amino acid sequences. One was found in the surviving pigs, and the other in symptomatic pigs. In total, 16 nonsynonymous SNPs (nsSNPs) resulting in codon changes were identified using bioinformatics software (SIFT and Polyphen v2) and web-based tools (MutPre and PredictSNP). Seven nsSNPs (P374-S, T448-S, P462-R, V464-P, Q478-H, L495-E, and P499-Q) were predicted to alter RelA protein function and stability, while 5 of these (P374-S, T448-S, P462-R, L495-E, and Q499-P) were predicted as disease-related SNPs.Additionally, the inflammatory cytokine levels of IFN-α, IL-10, and TNF-α at both the protein and the mRNA transcript levels were measured using ELISA and Real-Time PCR, respectively. The resulting data was used in correlation analysis to assess the association between cytokine levels and the RelA gene expression. Higher levels of IFN-α and detectable levels of IL-10 protein and RelA mRNA were observed in surviving pigs compared to healthy (non-infected). A positive correlation of IFN-α cytokine levels with RelA mRNA expression was also obtained. In conclusion, 7 polymorphic events in the coding region of the RelA gene may contribute to the tolerance of ASFV in pigs.

Genome characterization of Rift Valley fever virus isolated from cattle, goats and sheep during interepidemic periods in Kenya.

Rift Valley fever virus (RVFV) is a mosquito-borne RNA virus of the Phlebovirus genus in the phenuviridae family. Its genome is trisegmented with small (S), medium (M) and large (L) fragments. In nature, the virus exists as a single serotype that is responsible for outbreaks of Rift Valley fever (RVF), a zoonotic disease that often occurs in Africa and the Middle East. RVFV genomes are thought to undergo both recombination and reassortment and investigations of these events is important for monitoring the emergence of virulent strains and understanding the evolutionary characteristics of this virus. The aim of this study was to characterize the genomes of RVFV isolates from cattle, sheep, and goats collected during an interepidemic period in Kenya between June 2016 and November 2021. A total of 691 serum samples from cattle (n = 144), goats (n = 185) and sheep (n = 362) were analysed at the Central Veterinary Laboratories. The competitive IgM-capture ELISA, was used to screen the samples; 205 samples (29.67%) tested positive for RVFV. Of the 205 positive samples, 42 (20.5%) were from cattle, 57 (27.8%) from goats, and 106 (51.7%) from sheep. All the IgM-positive samples were further analyzed by qPCR, and 24 (11.71%) tested positive with Ct values ranging from 14.788 to 38.286. Two samples, 201808HABDVS from sheep and 201810CML3DVS from cattle, had Ct values of less than 20.0 and yielded whole genome sequences with 96.8 and 96.4 coverage, respectively. There was no statistically significant evidence of recombination in any of the three segments and also phylogenetic analysis showed no evidence of reassortment in the two isolated RVFV segments when compared with other isolates of different lineages from previous outbreaks whose genomes are deposited in the GenBank. No evidence of reassortment leaves room for other factors to be the most probable contributors of change in virulence, pathogenicity and emergence of highly virulent strains of the RVFV.

The first complete genome sequence of the African swine fever virus genotype X and serogroup 7 isolated in domestic pigs from the Democratic Republic of Congo.

BACKGROUND: African swine fever (ASF), a highly contagious hemorrhagic disease, affects domestic pigs in the Democratic Republic of Congo (DRC) where regular outbreaks are reported leading to high mortality rates approaching 100% in the affected regions. No study on the characteristics of the complete genome of strains responsible for ASF outbreaks in the South Kivu province of DRC is available, limited a better understanding of molecular evolution and spread of this virus within the country. The present study aimed at determining the complete genome sequence of ASFV strains genotype X involved in 2018-2019 ASF disease outbreaks in South Kivu province of DRC. MATERIALS AND METHODS: Genomic DNA of a spleen sample from an ASFV genotype X-positive domestic pig in Uvira, during the 2018-2019 outbreaks in South Kivu, was sequenced using the Illumina HiSeq X platform. Obtained trimmed reads using Geneious Prime 2020.0.4 were blasted against a pig reference genome then contigs were generated from the unmapped reads enriched in ASFV DNA using Spades implemented in Geneious 2020.0.4. The assembly of the complete genome sequence of ASFV was achieved from the longest overlapping contigs. The new genome was annotated with the genome annotation transfer utility (GATU) software and the CLC Genomics Workbench 8 software was further used to search for any ORFs that failed to be identified by GATU. Subsequent analyses of the newly determined Uvira ASFV genotype X genome were done using BLAST for databases search, CLUSTAL W for multiple sequences alignments and MEGA X for phylogeny. RESULTS: 42 Gbp paired-end reads of 150 bp long were obtained containing about 0.1% of ASFV DNA. The assembled Uvira ASFV genome, termed Uvira B53, was 180,916 bp long that could be assembled in 2 contigs. The Uvira B53genome had a GC content of 38.5%, encoded 168 open reading frames (ORFs) and had 98.8% nucleotide identity with the reference ASFV genotype X Kenya 1950. The phylogenetic relationship with selected representative genomes clustered the Uvira B53 strain together with ASFV genotype X reported to date (Kenya 1950 and Ken05/Tk1). Multiple genome sequences comparison with the two reference ASFV genotype X strains showed that 130 of the 168 ORFs were fully conserved in the Uvira B53. The other 38 ORFs were divergent mainly due to SNPs and indels (deletions and insertions). Most of 46 multigene family (MGF) genes identified were affected by various genetic variations. However, 8 MGF ORFs present in Kenya 1950 and Ken05/Tk1 were absent from the Uvira B53 genome including three members of MGF 360, four of MGF 110 and one of MGF 100 while one MGF ORF (MGF 360-1L) at the left end of the genome was truncated in Uvira B53. Moreover, ORFs DP96R and p285L were also absent in the Uvira B53 genome. In contrast, the ORF MGF 110-5L present in Uvira B53 and Ken05/Tk1 was missing in Kenya 1950. The analysis of the intergenic region between the I73R and I329L genes also revealed sequence variations between the three genotype X strains mainly characterized by a deletion of 69 bp in Uvira B53 and 36 bp in Kenya 1950, compared to Ken05/Tk1. Assessment of the CD2v (EP402R) antigen unveiled the presence of SNPs and indels particularly in the PPPKPY tandem repeat region between selected variants representing the eight serogroups reported to date. Uvira B53 had identical CD2v variable region to the Uganda (KM609361) strain, the only other ASFV serogroup 7 reported to date. CONCLUSION: We report the first complete genome sequence of an African swine fever virus (ASFV) p72 genotype X and CD2v serogroup 7, termed Uvira B53. This study provides additional insights on genetic characteristics and evolution of ASFV useful for tracing the geographical spread of ASF and essential for improved design of control and management strategies against ASF.

First detection of African swine fever (ASF) virus genotype X and serogroup 7 in symptomatic pigs in the Democratic Republic of Congo.

BACKGROUND: African swine fever (ASF) is a highly contagious and severe hemorrhagic viral disease of domestic pigs. The analysis of variable regions of African swine fever virus (ASFV) genome led to more genotypic and serotypic information about circulating strains. The present study aimed at investigating the genetic diversity of ASFV strains in symptomatic pigs in South Kivu province of the Democratic Republic of Congo (DRC). MATERIALS AND METHODS: Blood samples collected from 391 ASF symptomatic domestic pigs in 6 of 8 districts in South Kivu were screened for the presence of ASFV, using a VP73 gene-specific polymerase chain reaction (PCR) with the universal primer set PPA1-PPA2. To genotype the strains, we sequenced and compared the nucleotide sequences of PPA-positive samples at three loci: the C-terminus of B646L gene encoding the p72 protein, the E183L gene encoding the p54 protein, and the central hypervariable region (CVR) of the B602L gene encoding the J9L protein. In addition, to serotype and discriminate between closely related strains, the EP402L (CD2v) gene and the intergenic region between the I73R and I329L genes were analyzed. RESULTS: ASFV was confirmed in 26 of 391 pigs tested. However, only 19 and 15 PPA-positive samples, respectively, were successfully sequenced and phylogenetically analyzed for p72 (B646L) and p54 (E183L). All the ASFV studied were of genotype X. The CVR tetrameric repeat clustered the ASFV strains in two subgroups: the Uvira subgroup (10 TRS repeats, AAAABNAABA) and another subgroup from all other strains (8 TRS repeats, AABNAABA). The phylogenetic analysis of the EP402L gene clustered all the strains into CD2v serogroup 7. Analyzing the intergenic region between I73R and I329L genes revealed that the strains were identical but contained a deletion of a 33-nucleotide internal repeat sequence compared to ASFV strain Kenya 1950. CONCLUSION: ASFV genotype X and serogroup 7 was identified in the ASF disease outbreaks in South Kivu province of DRC in 2018-2019. This represents the first report of ASFV genotype X in DRC. CVR tetrameric repeat sequences clustered the ASFV strains studied in two subgroups. Our finding emphasizes the need for improved coordination of the control of ASF.

Molecular characterization of human coronaviruses and their circulation dynamics in Kenya, 2009-2012.

BACKGROUND: Human Coronaviruses (HCoV) are a common cause of respiratory illnesses and are responsible for considerable morbidity and hospitalization across all age groups especially in individuals with compromised immunity. There are six known species of HCoV: HCoV-229E, HCoV-NL63, HCoV-HKU1, HCoV-OC43, MERS-CoV and SARS-HCoV. Although studies have shown evidence of global distribution of HCoVs, there is limited information on their presence and distribution in Kenya. METHODS: HCoV strains that circulated in Kenya were retrospectively diagnosed and molecularly characterized. A total of 417 nasopharyngeal specimens obtained between January 2009 and December 2012 from around Kenya were analyzed by a real time RT-PCR using HCoV-specific primers. HCoV-positive specimens were subsequently inoculated onto monolayers of LL-CMK2 cells. The isolated viruses were characterized by RT-PCR amplification and sequencing of the partial polymerase (pol) gene. RESULTS: The prevalence of HCoV infection was as follows: out of the 417 specimens, 35 (8.4 %) were positive for HCoV, comprising 10 (2.4 %) HCoV-NL63, 12 (2.9 %) HCoV-OC43, 9 (2.1 %) HCoV-HKU1, and 4 (1 %) HCoV-229E. The Kenyan HCoV strains displayed high sequence homology to the prototypes and contemporaneous strains. Evolution analysis showed that the Kenyan HCoV-OC43 and HCoV-NL63 isolates were under purifying selection. Phylogenetic evolutionary analyses confirmed the identities of three HCoV-HKU1, five HCoV-NL63, eight HCoV-OC43 and three HCoV-229E. CONCLUSIONS: There were yearly variations in the prevalence and circulation patterns of individual HCoVs in Kenya. This paper reports on the first molecular characterization of human Coronaviruses in Kenya, which play an important role in causing acute respiratory infections among children.

Genetic divergence of Chikungunya virus plaque variants from the Comoros Island (2005).

Chikungunya virus (CHIKV) from a human sample collected during the 2005 Chikungunya outbreak in the Comoros Island, showed distinct and reproducible large (L2) and small (S7) plaques which were characterized in this study. The parent strain and plaque variants were analysed by in vitro growth kinetics in different cell lines and their genetic similarity assessed by whole genome sequencing, comparative sequence alignment and phylogenetic analysis. In vitro growth kinetic assays showed similar growth patterns of both plaque variants in Vero cells but higher viral titres of S7 compared to L2 in C6/36 cells. Amino acids (AA) alignments of the CHIKV plaque variants and S27 African prototype strain, showed 30 AA changes in the non-structural proteins (nsP) and 22 AA changes in the structural proteins. Between L2 and S7, only two AAs differences were observed. A missense substitution (C642Y) of L2 in the nsP2, involving a conservative AA substitution and a nonsense substitution (R524X) of S7 in the nsP3, which has been shown to enhance O'nyong-nyong virus infectivity and dissemination in Anopheles mosquitoes. The phenotypic difference observed in plaque size could be attributed to one of these AA substitutions. Phylogenetic analysis showed that the parent strain and its variants clustered closely together with each other and with Indian Ocean CHIKV strains indicating circulation of isolates with close evolutionary relatedness in the same outbreak. These observations pave way for important functional studies to understand the significance of the identified genetic changes in virulence and viral transmission in mosquito and mammalian hosts.

Natural vertical transmission of ndumu virus in Culex pipiens (Diptera: Culicidae) mosquitoes collected as larvae.

Ndumu virus (NDUV) is a member of the family Togaviridae and genus Alphavirus. In Kenya, the virus has been isolated from a range of mosquito species but has not been associated with human or animal morbidity. Little is know about the transmission dynamics or vertebrate reservoirs of this virus. NDUV was isolated from two pools of female Culex pipiens mosquitoes, IJR37 (n = 18) and IJR73 (n = 3), which were collected as larvae on 15 April 2013 from two dambos near the village of Marey, Ijara District, Garissa County, Kenya, and reared to adults and identified to species. These results represent the first field evidence of vertical transmission of NDUV among mosquitoes.

Risk factors of African swine fever virus in suspected infected pigs in smallholder farming systems in South-Kivu province, Democratic Republic of Congo.

BACKGROUND: African swine fever (ASF) is an infectious viral disease of domestic pigs that presents as a hemorrhagic fever, and for which no effective vaccine is available. The disease has a serious negative social and economic impact on pig keepers. There is limited information on the potential risk factors responsible for the spread of ASF in South Kivu. OBJECTIVE: The aim of this study was to determine the potential risk factors associated with ASF infection in suspected ASF virus (ASFV)-infected pigs. METHODS: We sampled whole blood from 391 pigs. Additionally, 300 pig farmers were interviewed using a structured questionnaire. Viral DNA was detected by using the real-time polymerase chain reaction technique. RESULTS: The majority of pigs sampled, 78% (95% confidence interval [CI], 74.4-82.6), were of local breeds. Over half, 60.4% (95% CI, 55.5-65.2), were female, and most of them, 90.5% (95% CI, 87.6-93.4), were adult pigs (> 1 year old). Viral DNA was detected in 72 of the 391 sampled pigs, indicating an overall infection rate of 18.4% (95% CI, 14.5-22.4). Multivariable logistic regression analysis revealed several risk factors positively associated with ASFV infection: feeding with swill in pen (odds ratio [OR], 3.8; 95% CI, 2.12-6.77); mixed ages of pigs in the same pen (OR, 3.3; 95% CI, 1.99-5.57); introduction of new animals to the farm (OR, 5.4; 95% CI, 1.91-15.28). The risk factors that were negatively (protective) correlated with ASFV positivity were the presence of male animals and the use of an in-pen breeding system. CONCLUSION: Local pig farmers should be encouraged to adopt proper husbandry and feeding practices in order to increase the number of ASF-free farms.

Detection of circulating hepatitis B virus immune escape and polymerase mutants among HBV-positive patients attending Institut Pasteur de Bangui, Central African Republic.

BACKGROUND: Previous studies in the Central African Republic (CAR) have reported the presence of hepatitis B virus (HBV) recombinant genotype E/D and a suspicion of immune escape mutants (IEMs), without further investigation into their impact on prevention and diagnosis. Consequently, this study investigated HBV mutations among hepatitis B surface antigen (HBsAg)-positive patients attending Institut Pasteur de Bangui in the CAR. METHODS: Sera from a total of 118 HBsAg-positive patients with no previous history of HBV treatment or vaccination at the Institut Pasteur de Bangui, were sampled between 2017 and 2019. Subsequently, the region spanning the surface and polymerase genes of HBV was amplified by PCR and sequenced. HBV sequences were genotyped/subgenotyped by phylogenetic analysis and serotyped based on predicted amino acid residues at positions s122, s127, s140, s159, and s160. They were then analyzed for HBV IEMs and polymerase mutations. RESULTS: The region spanning the surface and polymerase genes was successfully amplified and sequenced for 51 samples. Of the HBV sequences, 49 were genotype E and two were genotype A subgenotype A1; these were serotyped as ayw4 and ayw1, respectively. Potential IEMs sY100C, sA128V, and sM133T, and several polymerase mutants were identified. CONCLUSIONS: This study raises awareness of the need for further studies to be conducted on a large scale to better understand HBV mutations for improved disease control and prevention strategies in the country.

Comparative Transcriptomics of the Bovine Apicomplexan Parasite Theileria parva Developmental Stages Reveals Massive Gene Expression Variation and Potential Vaccine Antigens.

Theileria parva is a protozoan parasite that causes East Coast fever (ECF), an economically important disease of cattle in Africa. It is transmitted mainly by the tick Rhipicephalus appendiculatus. Research efforts to develop a subunit vaccine based on parasite neutralizing antibodies and cytotoxic T-lymphocytes have met with limited success. The molecular mechanisms underlying T. parva life cycle stages in the tick vector and bovine host are poorly understood, thus limiting progress toward an effective and efficient control of ECF. Transcriptomics has been used to identify candidate vaccine antigens or markers associated with virulence and disease pathology. Therefore, characterization of gene expression throughout the parasite's life cycle should shed light on host-pathogen interactions in ECF and identify genes underlying differences in parasite stages as well as potential, novel therapeutic targets. Recently, the first gene expression profiling of T. parva was conducted for the sporoblast, sporozoite, and schizont stages. The sporozoite is infective to cattle, whereas the schizont is the major pathogenic form of the parasite. The schizont can differentiate into piroplasm, which is infective to the tick vector. The present study was designed to extend the T. parva gene expression profiling to the piroplasm stage with reference to the schizont. Pairwise comparison revealed that 3,279 of a possible 4,084 protein coding genes were differentially expressed, with 1,623 (49%) genes upregulated and 1,656 (51%) downregulated in the piroplasm relative to the schizont. In addition, over 200 genes were stage-specific. In general, there were more molecular functions, biological processes, subcellular localizations, and pathways significantly enriched in the piroplasm than in the schizont. Using known antigens as benchmarks, we identified several new potential vaccine antigens, including TP04_0076 and TP04_0640, which were highly immunogenic in naturally T. parva-infected cattle. All the candidate vaccine antigens identified have yet to be investigated for their capacity to induce protective immune response against ECF.

Evidence for the presence of African swine fever virus in apparently healthy pigs in South-Kivu Province of the Democratic Republic of Congo.

African swine fever (ASF) is the most important disease constraining smallholder pig production in the Democratic Republic of Congo, causing high mortality in domestic pigs with severe impacts on the livelihoods of local populations. This study was conducted with the aim of determining the prevalence of ASF and circulating virus genotypes in asymptomatic pigs raised on smallholder farms in the South Kivu province to understand the transmission dynamics of ASF and ultimately improving disease control. A cross-sectional survey was carried out in 5 districts where 267 pig blood were screened for both antibody and viral genome using indirect Enzyme Linked Immunosorbent Assay (ELISA) and polymerase chain reaction (PCR) respectively. Additionally, amplicons from PCR positive samples were sequenced by Sanger method for genetic analysis of ASF virus (ASFV) based on the C-terminal region of the B646L gene that encodes the major capsid protein p72 and the gene E183L encoding the p54 protein. The overall seroprevalence obtained based on antibody to p30 protein was 37 % and was significantly higher (P < 0.05) in adult (>1 year) animals (44.7 %) than in younger (<1 year) ones (33.5 %). Moreover, the seropositivity varied significantly (P < 0.05) according to the pig husbandry system practiced within the districts investigated with Uvira (55 %) and Mwenga (42.2 %) having the highest ASFV antibodies, while the lowest (10.5 %) were in Kalehe. Free-range pigs exhibited a higher level of seropositivity to ASFV antibody (68.9 %) than pigs kept in the pigsty housing system (21.6 %). However, no statistically significant differences (P > 0.05) were observed when sex of the animal and breed were factored. PCR detection of ASFV amplified a specific band of expected size (257 bp) in 61 out of 267 blood samples, confirming the presence of the viral DNA in 22.8 % of asymptomatic domestic pigs. Statistical analysis revealed that ASFV infection in domestic pigs varied significantly (p < 0.001) according to geographical location and breed, with the highest infection rate found in Walungu district (33.7 %) while the lowest was registered in Kalehe (15.8 %). Local pigs (27.2 %) were more infected than crosses (9.2 %). Phylogenetic analyses based on partial sequences of the p72 and p54 genes revealed that all the ASFV detected belonged to genotype IX, which has previously been reported in other parts of DR Congo, and was clustered together with isolates from Kenya, Uganda and Republic of Congo. This study avails the first evidence of the presence of ASF virus in domestic pigs in the absence of outbreaks in South Kivu province, eastern DR Congo, indicating a need to raise awareness among pig farmers and veterinary authorities on the application of biosecurity measures and good husbandry practices to control the disease.

Knowledge and practices regarding Middle East Respiratory Syndrome Coronavirus among camel handlers in a Slaughterhouse, Kenya, 2015.

Dromedary camels are implicated as reservoirs for the zoonotic transmission of Middle East Respiratory Syndrome coronavirus (MERS-CoV) with the respiratory route thought to be the main mode of transmission. Knowledge and practices regarding MERS among herders, traders and slaughterhouse workers were assessed at Athi-River slaughterhouse, Kenya. Questionnaires were administered, and a check list was used to collect information on hygiene practices among slaughterhouse workers. Of 22 persons, all washed hands after handling camels, 82% wore gumboots, and 65% wore overalls/dustcoats. None of the workers wore gloves or facemasks during slaughter processes. Fourteen percent reported drinking raw camel milk; 90% were aware of zoonotic diseases with most reporting common ways of transmission as: eating improperly cooked meat (90%), drinking raw milk (68%) and slaughter processes (50%). Sixteen (73%) were unaware of MERS-CoV. Use of personal protective clothing to prevent direct contact with discharges and aerosols was lacking. Although few people working with camels were interviewed, those met at this centralized slaughterhouse lacked knowledge about MERS-CoV but were aware of zoonotic diseases and their transmission. These findings highlight need to disseminate information about MERS-CoV and enhance hygiene and biosafety practices among camel slaughterhouse workers to reduce opportunities for potential virus transmission.

Serotype and genetic diversity of human rhinovirus strains that circulated in Kenya in 2008.

BACKGROUND: Human rhinoviruses (HRVs) are a well-established cause of the common cold and recent studies indicated that they may be associated with severe acute respiratory illnesses (SARIs) like pneumonia, asthma, and bronchiolitis. Despite global studies on the genetic diversity of the virus, the serotype diversity of these viruses across diverse geographic regions in Kenya has not been characterized. OBJECTIVES: This study sought to characterize the serotype diversity of HRV strains that circulated in Kenya in 2008. METHODS: A total of 517 archived nasopharyngeal samples collected in a previous respiratory virus surveillance program across Kenya in 2008 were selected. Participants enrolled were outpatients who presented with influenza-like (ILI) symptoms. Real-time RT-PCR was employed for preliminary HRV detection. HRV-positive samples were amplified using RT-PCR and thereafter the nucleotide sequences of the amplicons were determined followed by phylogenetic analysis. RESULTS: Twenty-five percent of the samples tested positive for HRV. Phylogenetic analysis revealed that the Kenyan HRVs clustered into three main species comprising HRV-A (54%), HRV-B (12%), and HRV-C (35%). Overall, 20 different serotypes were identified. Intrastrain sequence homology among the Kenyan strains ranged from 58% to 100% at the nucleotide level and 55% to 100% at the amino acid level. CONCLUSION: These results show that a wide range of HRV serotypes with different levels of nucleotide variation were present in Kenya. Furthermore, our data show that HRVs contributed substantially to influenza-like illness in Kenya in 2008.

Seroepidemiology of selected arboviruses in febrile patients visiting selected health facilities in the lake/river basin areas of Lake Baringo, Lake Naivasha, and Tana River, Kenya.

INTRODUCTION: Arboviruses cause emerging and re-emerging infections affecting humans and animals. They are spread primarily by blood-sucking insects such as mosquitoes, ticks, midges, and sandflies. Changes in climate, ecology, demographic, land-use patterns, and increasing global travel have been linked to an upsurge in arboviral disease. Outbreaks occur periodically followed by persistent low-level circulation. AIM: This study was undertaken to determine the seroepidemiology of selected arboviruses among febrile patients in selected lake/river basins of Kenya. METHODS: Using a hospital-based cross-sectional descriptive survey, febrile patients were recruited and their serum samples tested for exposure to immunoglobulin M (IgM) and IgG antibodies against Crimean-Congo hemorrhagic fever virus (CCHFV), Rift Valley fever virus (RVFV), West Nile virus (WNV), and chikungunya virus (CHIKV). Samples positive for CHIKV and WNV were further confirmed by the plaque reduction neutralization test (PRNT). RESULTS: Of the 379 samples examined, 176 were IgG positive for at least one of these arboviruses (46.4%, 95% confidence interval [CI] 41.4-51.5%). Virus-specific prevalence for CCHF, RVF, WN, and CHIK was 25.6%, 19.5%, 12.4%, and 2.6%, respectively. These prevalences varied significantly with geographical site (p<0.001), with Tana recording the highest overall arboviral seropositivity. PRNT results for Alphaviruses confirmed that the actual viruses circulating in Baringo were Semliki Forest virus (SFV) and CHIKV, o'nyong nyong virus (ONNV) in Naivasha, and SFV and Sindbis virus (SINDV) in Tana delta. Among the flaviviruses tested, WNV was circulating in all the three sites. CONCLUSION: There is a high burden of febrile illness in humans due to CCHFV, RVFV, WNV, and CHIKV infection in the river/lake basin regions of Kenya.

Development and Evaluation of an in-House IgM-Capture ELISA for the Detection of Chikungunya and Its Application to a Dengue Outbreak Situation in Kenya in 2013.

Chikungunya (CHIK) is a mosquito-borne viral disease. In the 2004 CHIK outbreak in Kenya, diagnosis was delayed because of the lack of accurate diagnostics. Therefore, this study aimed to develop and evaluate an in-house IgM-capture enzyme linked immunosorbent assay (ELISA) (in-house ELISA) for the detection of chikungunya virus (CHIKV) infections. Anti-CHIKV antibodies were raised in rabbits, purified and conjugated to horseradish peroxidase. These anti-CHIKV antibodies and cell-culture derived antigen were used to develop the ELISA. To validate the in-house ELISA, 148 patient sera from the 2005 Comoros CHIK outbreak were tested with centers for disease control and prevention (CDC) IgM-capture ELISA (CDC ELISA) and focus reduction neutralization test (FRNT) as reference assays. The in-house ELISA had a sensitivity of 97.6% and specificity of 81.3% compared to the CDC ELISA and a sensitivity of 91.1% and specificity of 96.7% compared to FRNT. Furthermore, 254 clinically suspected dengue patient samples from Eastern Kenya, collected in 2013, were tested for CHIKV IgM using the in-house ELISA. Out of the 254 samples, 26 (10.2%) were IgM positive, and of these 26 samples, 17 were further analyzed by FRNT and 14 (82.4%) were positive. The in-house ELISA was able to diagnose CHIKV infection among suspected dengue cases in the 2013 outbreak.

Blood meal analysis and virus detection in blood-fed mosquitoes collected during the 2006-2007 Rift Valley fever outbreak in Kenya.

BACKGROUND: Rift Valley fever (RVF) is a zoonosis of domestic ruminants in Africa. Blood-fed mosquitoes collected during the 2006-2007 RVF outbreak in Kenya were analyzed to determine the virus infection status and animal source of the blood meals. MATERIALS AND METHODS: Blood meals from individual mosquito abdomens were screened for viruses using Vero cells and RT-PCR. DNA was also extracted and the cytochrome c oxidase 1 (CO1) and cytochrome b (cytb) genes amplified by PCR. Purified amplicons were sequenced and queried in GenBank and Barcode of Life Database (BOLD) to identify the putative blood meal sources. RESULTS: The predominant species in Garissa were Aedes ochraceus, (n=561, 76%) and Ae. mcintoshi, (n=176, 24%), and Mansonia uniformis, (n=24, 72.7%) in Baringo. Ae. ochraceus fed on goats (37.6%), cattle (16.4%), donkeys (10.7%), sheep (5.9%), and humans (5.3%). Ae. mcintoshi fed on the same animals in almost equal proportions. RVFV was isolated from Ae. ochraceus that had fed on sheep (4), goats (3), human (1), cattle (1), and unidentified host (1), with infection and dissemination rates of 1.8% (10/561) and 50% (5/10), respectively, and 0.56% (1/176) and 100% (1/1) in Ae. mcintoshi. In Baringo, Ma. uniformis fed on sheep (38%), frogs (13%), duikers (8%), cattle (4%), goats (4%), and unidentified hosts (29%), with infection and dissemination rates of 25% (6/24) and 83.3% (5/6), respectively. Ndumu virus (NDUV) was also isolated from Ae. ochraceus with infection and dissemination rates of 2.3% (13/561) and 76.9% (10/13), and Ae. mcintoshi, 2.8% (5/176) and 80% (4/5), respectively. Ten of the infected Ae. ochraceus had fed on goats, sheep (1), and unidentified hosts (2), and Ae. mcintoshi on goats (3), camel (1), and donkey (1). CONCLUSION: This study has demonstrated that RVFV and NDUV were concurrently circulating during the outbreak, and sheep and goats were the main amplifiers of these viruses respectively.

The viral aetiology of influenza-like illnesses in Kampala and Entebbe, Uganda, 2008.

BACKGROUND: As the threat of zoonoses and the emergence of pandemic-prone respiratory viruses increases, there is a need to establish baseline information on the incidence of endemic pathogens in countries worldwide. OBJECTIVES: To investigate the presence of viruses associated with influenza-like illnesses (ILI) in Uganda. METHODS: A cross-sectional study was conducted in which nasopharyngeal swab specimens were collected from patients diagnosed with ILI in Kampala and Entebbe between 14 August 2008 - 15 December 2008. A multiplex polymerase chain reaction assay for detecting 12 respiratory viruses was used. RESULTS: A total of 369 patients (52.3% females) was enrolled; the median age was 6 years (range 1-70). One or more respiratory viruses were detected in 172 (46.6%) cases and their prevalence were influenza A virus (19.2%), adenovirus (8.7%), human rhinovirus A (7.9%), coronavirus OC43 (4.3%), parainfluenza virus 1 (2.7%), parainfluenza virus 3 (2.7%), influenza B virus (2.2%), respiratory syncytial virus B (2.2%), human metapneumovirus (1.4%), respiratory syncytial virus A (1.1%), parainfluenza virus 2 (0.5%) and coronavirus 229E (0.5%). There were 24 (14.0%) mixed infections. CONCLUSIONS: This study identified some of the respiratory viruses associated with ILI in Uganda. The circulation of some of the viruses was previously unknown in the study population. These results are useful in order to guide future surveillance and case management strategies involving respiratory illnesses in Uganda.

Differing burden and epidemiology of non-Typhi Salmonella bacteremia in rural and urban Kenya, 2006-2009.

BACKGROUND: The epidemiology of non-Typhi Salmonella (NTS) bacteremia in Africa will likely evolve as potential co-factors, such as HIV, malaria, and urbanization, also change. METHODS: As part of population-based surveillance among 55,000 persons in malaria-endemic, rural and malaria-nonendemic, urban Kenya from 2006-2009, blood cultures were obtained from patients presenting to referral clinics with fever ≥38.0°C or severe acute respiratory infection. Incidence rates were adjusted based on persons with compatible illnesses, but whose blood was not cultured. RESULTS: NTS accounted for 60/155 (39%) of blood culture isolates in the rural and 7/230 (3%) in the urban sites. The adjusted incidence in the rural site was 568/100,000 person-years, and the urban site was 51/100,000 person-years. In both sites, the incidence was highest in children <5 years old. The NTS-to-typhoid bacteremia ratio in the rural site was 4.6 and in the urban site was 0.05. S. Typhimurium represented >85% of blood NTS isolates in both sites, but only 21% (urban) and 64% (rural) of stool NTS isolates. Overall, 76% of S. Typhimurium blood isolates were multi-drug resistant, most of which had an identical profile in Pulse Field Gel Electrophoresis. In the rural site, the incidence of NTS bacteremia increased during the study period, concomitant with rising malaria prevalence (monthly correlation of malaria positive blood smears and NTS bacteremia cases, Spearman's correlation, p = 0.018 for children, p = 0.16 adults). In the rural site, 80% of adults with NTS bacteremia were HIV-infected. Six of 7 deaths within 90 days of NTS bacteremia had HIV/AIDS as the primary cause of death assigned on verbal autopsy. CONCLUSIONS: NTS caused the majority of bacteremias in rural Kenya, but typhoid predominated in urban Kenya, which most likely reflects differences in malaria endemicity. Control measures for malaria, as well as HIV, will likely decrease the burden of NTS bacteremia in Africa.

Detection and localisation of picorna-like virus particles in tissues of Varroa destructor, an ectoparasite of the honey bee, Apis mellifera.

Virus-like particles, 27 nm in diameter, were observed in extracts of individual Varroa destructor mites and in sections of mite tissue. Application of a purification procedure resulted in virus preparations that were used to prepare an antiserum to detect the virus in individual mites. Immunohistology studies showed that the gastric caecae were heavily infected, whereas no immunostaining could be detected in other mite tissues or organs, like the salivary glands, brain, rectum or reproductive organs. By electron microscopy large aggregates of virus-like particles in para-crystalline lattices were found in cells of the gastric caecae. The particles, reminiscent to picorna-like viruses, occurred mainly in the cytoplasm, whereas some virus particles were sparsely scattered in vacuoles. Occasionally, particles were observed in membrane-bound vesicles or in long tubular membrane structures in the cytoplasm. The accumulation of the picorna-like virus particles in the cytoplasm and the presence of the virus in membrane structures give a strong indication that the virus replicates in the mite.

The 5' non-translated region of Varroa destructor virus 1 (genus Iflavirus): structure prediction and IRES activity in Lymantria dispar cells.

Structure prediction of the 5' non-translated region (NTR) of four iflavirus RNAs revealed two types of potential internal ribosome entry site (IRES), which are discriminated by size and level of complexity, in this group of viruses. In contrast to the intergenic IRES of dicistroviruses, the potential 5' IRES structures of iflaviruses do not have pseudoknots. To test the activity of one of these, a bicistronic construct was made in which the 5' NTR of Varroa destructor virus 1 (VDV-1) containing a putative IRES was cloned in between two reporter genes, enhanced green fluorescent protein and firefly luciferase (Fluc). The presence of the 5' NTR of VDV-1 greatly enhanced the expression levels of the second reporter gene (Fluc) in Lymantria dispar Ld652Y cells. The 5' NTR was active in a host-specific manner, as it showed lower activity in Spodoptera frugiperda Sf21 cells and no activity in Drosophila melanogaster S2 cells.