A survey of tick species on cattle and African buffaloes in the Tsavo Conservation Area, Kenya

The objective of this study was to compare the tick species that infest African buffaloes (Syncerus caffer) with those that infest domestic cattle in the Tsavo Conservation Area in Kenya. To this end ticks were collected from cattle and African buffaloes within the study locality. Fourteen tick species belonging to the genera Amblyomma, Hyalomma and Rhipicephalus were collected. Eight species, namely Amblyomma gemma, Amblyomma lepidum, Hyalomma albiparmatum, Hyalomma rufipes, Hyalomma truncatum, Rhipicephalus evertsi evertsi, Rhipicephalus pravus and Rhipicephalus pulchellus, were collected from cattle and from buffaloes sampled during the study period. Three species, namely Hyalomma impeltatum, Rhipicephalus humeralis and Rhipicephalus praetextatus, were present only on buffaloes, and three, Rhipicephalus (Boophilus) sp., Rhipicephalus kochi, and Rhipicephalus muehlensi, were collected only from cattle. Of all the ticks collected, those of the genus Amblyomma are associated with the highest risk of disease and possibly with severe losses in cattle in the area. New locality records for H. impeltatum and H. truncatum were determined and the first locality records for R. praetextatus sensu stricto in Kenya are reported.Dissertation (MSc)--University of Pretoria, 2011.Veterinary Tropical DiseasesMScUnrestricte

Expressed centromere specific histone 3 (CENH3) variants in cultivated triploid and wild diploid bananas (Musa spp.)

Open Access JournalCentromeres are specified by a centromere specific histone 3 (CENH3) protein, which exists in a complex environment, interacting with conserved proteins and rapidly evolving satellite DNA sequences. The interactions may become more challenging if multiple CENH3 versions are introduced into the zygote as this can affect post-zygotic mitosis and ultimately sexual reproduction. Here, we characterize CENH3 variant transcripts expressed in cultivated triploid and wild diploid progenitor bananas. We describe both splice- and allelic-[Single Nucleotide Polymorphisms (SNP)] variants and their effects on the predicted secondary structures of protein. Expressed CENH3 transcripts from six banana genotypes were characterized and clustered into three groups (MusaCENH-1A, MusaCENH-1B, and MusaCENH-2) based on similarity. The CENH3 groups differed with SNPs as well as presence of indels resulting from retained and/or skipped exons. The CENH3 transcripts from different banana genotypes were spliced in either 7/6, 5/4 or 6/5 exons/introns. The 7/6 and the 5/4 exon/intron structures were found in both diploids and triploids, however, 7/6 was most predominant. The 6/5 exon/introns structure was a result of failure of the 7/6 to splice correctly. The various transcripts obtained were predicted to encode highly variable N-terminal tails and a relatively conserved C-terminal histone fold domain (HFD). The SNPs were predicted in some cases to affect the secondary structure of protein by lengthening or shorting the affected domains. Sequencing of banana CENH3 transcripts predicts SNP variations that affect amino acid sequences and alternatively spliced transcripts. Most of these changes affect the N-terminal tail of CENH3

Physiological response to chemical immobilization: a case study of etorphine-azaperone in free-ranging plains zebra (Equus quagga) in Kenya

Predictable immobilization of wild zebras is challenging and there is massive variation in opiate response within different species.Etorphine combined with azaperone is considered the protocol of choice, but no studies have investigated the physiological response to this procedure of immobilization in plains zebras. Eleven free-ranging plains zebras (Equus quagga) were immobilized in Kenya using a combination of etorphine 0.019 ± 0.003 mg/kg and azaperone 0.27 ± 0.05 mg/kg administered intramuscularly with a projectile dart. After recumbency, an arterial sample was performed for blood gas analysis and physiological parameters were recorded every five minutes.Descriptive scores were given to the exertion resulting from high-speed chasing and to the quality of induction, immobilization and recovery. Diprenorphine or naltrexone were used for opioid antagonism. In all zebras, the combination induced quick inductions within 3.5 ± 0.8 minutes and provided reliable recumbencies without attempts to stand for the entire duration of the immobilization.The average heart rates, respiratory rates and mean arterial blood pressure recorded were 102 ± 42 beats/minute, 18 ± 4 breaths/minute and 145 ± 28 mmHg respectively. Arterial gas analyses demonstrated mild to severe and partially compensated metabolic acidosis and hypoxia, while electrolytes were within equids range. In particular, higher exertion levels during the chasing were significantly correlated to worse immobilization scores (p=0.008) and hyperthermia occurrence (p=0.0012) and non-significantly to more severe acidosis. Recoveries from anaesthesia were smooth, on average 121 ± 38 seconds after diprenorphine/naltrexone administration.           Etorphine-azaperone combination produced physiological alterations in free-ranging plains zebra such as tachycardia, hypertension, metabolic acidosis and hypoxemia. However, these preliminary results indicate that high-speed chase might be responsible for the physiological imbalance and that this drug combination does not suppress the compensatory response. Regardless of the metabolic status, recover from immobilization was uneventful and all zebras went back to normal behavior thereafter

Ticks (Acari : Ixodidae) infesting cattle and African buffaloes in the Tsavo conservation area, Kenya

Several ixodid tick species are shared between domestic cattle and African buffaloes (Syncerus caffer). So too, are a number of tick-borne diseases. The aim of the study was to compare the species composition of ticks that infest cattle and buffaloes utilising the same habitat within the Tsavo Conservation Area, Kenya. To this end, 25 cattle and 62 buffaloes were each opportunistically sampled for ticks on a single occasion in February 2010. Eight species, namely Amblyomma gemma, Amblyomma lepidum, Hyalomma albiparmatum, Hyalomma rufipes, Hyalomma truncatum, Rhipicephalus evertsi evertsi, Rhipicephalus pravus and Rhipicephalus pulchellus infested both cattle and buffaloes. Three species, Rhipicephalus (Boophilus) sp., Rhipicephalus kochi, and Rhipicephalus muehlensi were collected only from cattle, and three species, Hyalomma impeltatum, Rhipicephalus humeralis and Rhipicephalus praetextatus were present only on buffaloes. The attachment sites of the various tick species were also recorded. New locality records for H. impeltatum and H. truncatum and the first confirmed locality record for Rhipicephalus praetextatus sensu stricto in Kenya were documented.Grants from the National Research Foundation to BLP and IGHhttp://www.ojvr.orgam2013ab201

The threat of root-knot nematodes (Meloidogyne spp.) in Africa : a review

Meloidogyne species pose a significant threat to crop production in Africa due to the losses they cause in a wide range of agricultural crops. The direct and indirect damage caused by various Meloidogyne species results in delayed maturity, toppling, reduced yields and quality of crop produce, high costs of production and therefore loss of income. In addition, emergence of resistance-breaking Meloidogyne species has partly rendered various pest management programmes already in place ineffective, therefore putting food security of the continent at risk. It is likely that more losses may be experienced in the future due to the on-going withdrawal of nematicides. To adequately address the threat of Meloidogyne species in Africa, an accurate assessment and understanding of the species present, genetic diversity, population structure, parasitism mechanisms and how each of these factors contribute to the overall threat posed by Meloidogyne species is important. Thus, the ability to accurately characterize and identify Meloidogyne species is crucial if the threat of Meloidogyne species to crop production in Africa is to be effectively tackled. This review discusses the use of traditional versus molecular-based identification methods of Meloidogyne species and how accurate identification using a polyphasic approach can negate the eminent threat of root knot nematodes in crop production. The potential threat to Africa posed by highly damaging and resistance-breaking populations of ‘emerging’ Meloidogyne species is also examinedNational Research Foundation (NRF) and the University of Pretoria.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-3059hb201

表紙、標題紙

2017年2月2日(木) 於:早稲田大学 小野記念講

DIGOXIN AND RISK OF DEATH IN ADULTS WITH ATRIAL FIBRILLATION: THE ATRIA-CVRN STUDY

PCR primer sequences for each gene marker amplified and their corresponding annealing temperatures. (DOCX 15 kb

Assessment of molecular markers for anti-malarial drug resistance after the introduction and scale-up of malaria control interventions in western Kenya

Background Although it is well known that drug pressure selects for drug-resistant parasites, the role of transmission reduction by insecticide-treated bed nets (ITNs) on drug resistance remains unclear. In this study, the drug resistance profile of current and previous first-line anti-malarials in Kenya was assessed within the context of drug policy change and scale-up of ITNs. National first-line treatment changed from chloroquine (CQ) to sulphadoxine-pyrimethamine (SP) in 1998 and to artemether-lumefantrine (AL) in 2004. ITN use was scaled-up in the Asembo, Gem and Karemo areas of western Kenya in 1997, 1999 and 2006, respectively. Methods Smear-positive samples (N = 253) collected from a 2007 cross-sectional survey among children in Asembo, Gem and Karemo were genotyped for mutations in pfcrt and pfmdr1 (CQ), dhfr and dhps (SP), and at pfmdr-N86 and the gene copy number in pfmdr1 (lumefantrine). Results were compared among the three geographic areas in 2007 and to retrospective molecular data from children in Asembo in 2001. Results In 2007, 69 and 85% of samples harboured the pfmdr1-86Y mutation and dhfr/dhps quintuple mutant, respectively, with no significant differences by study area. However, the prevalence of the pfcrt-76T mutation differed significantly among areas (p <0.02), between 76 and 94%, with the highest prevalence in Asembo. Several 2007 samples carried mutations at dhfr-164L, dhps-436A, or dhps-613T. From 2001 to 2007, there were significant increases in the pfcrt-76T mutation from 82 to 94% (p <0.03), dhfr/dhps quintuple mutant from 62 to 82% (p <0.03), and an increase in the septuple CQ and SP combined mutant haplotype, K 76 Y 86 I 51 R 59 N 108 G 437 E 540 , from 28 to 39%. The prevalence of the pfmdr1-86Y mutation remained unchanged. All samples were single copy for pfmdr1. Conclusions Molecular markers associated with lumefantrine resistance were not detected in 2007. More recent samples will be needed to detect any selective effects by AL. The prevalence of CQ and SP resistance markers increased from 2001 to 2007 in the absence of changes in transmission intensity. In 2007, only the prevalence of pfcrt-76T mutation differed among study areas of varying transmission intensity. Resistant parasites were most likely selected by sustained drug pressure from the continued use of CQ, SP, and mechanistically similar drugs, such as amodiaquine and cotrimoxazole. There was no clear evidence that differences in transmission intensity, as a result of ITN scale-up, influenced the prevalence of drug resistance molecular markers

Effects of transmission reduction by insecticide-treated bed nets (ITNs) on parasite genetics population structure: I. The genetic diversity of Plasmodium falciparum parasites by microsatellite markers in western Kenya

<p>Abstract</p> <p>Background</p> <p>Insecticide-treated bed nets (ITNs) reduce malaria transmission and are an important prevention tool. However, there are still information gaps on how the reduction in malaria transmission by ITNs affects parasite genetics population structure. This study examined the relationship between transmission reduction from ITN use and the population genetic diversity of <it>Plasmodium falciparum </it>in an area of high ITN coverage in western Kenya.</p> <p>Methods</p> <p>Parasite genetic diversity was assessed by scoring eight single copy neutral multilocus microsatellite (MS) markers in samples collected from <it>P. falciparum-</it>infected children (< five years) before introduction of ITNs (1996, baseline, n = 69) and five years after intervention (2001, follow-up, n = 74).</p> <p>Results</p> <p>There were no significant changes in overall high mixed infections and unbiased expected heterozygosity between baseline (%M_A= 94% and H_e= 0.75) and follow up (%M_A= 95% and H_e= 0.79) years. However, locus specific analysis detected significant differences for some individual loci between the two time points. Pfg377 loci, a gametocyte-specific MS marker showed significant increase in mixed infections and H_ein the follow up survey (%M_A= 53% and H_e= 0.57) compared to the baseline (%M_A= 30% and H_e= 0.29). An opposite trend was observed in the erythrocyte binding protein (EBP) MS marker. There was moderate genetic differentiation at the Pfg377 and TAA60 loci (F_ST= 0.117 and 0.137 respectively) between the baseline and post-ITN parasite populations. Further analysis revealed linkage disequilibrium (LD) of the microsatellites in the baseline (14 significant pair-wise tests and <it>I^S_A</it>= 0.016) that was broken in the follow up parasite population (6 significant pairs and <it>I^S_A</it>= 0.0003). The locus specific change in H_e, the moderate population differentiation and break in LD between the baseline and follow up years suggest an underlying change in population sub-structure despite the stability in the overall genetic diversity and multiple infection levels.</p> <p>Conclusions</p> <p>The results from this study suggest that although <it>P. falciparum </it>population maintained an overall stability in genetic diversity after five years of high ITN coverage, there was significant locus specific change associated with gametocytes, marking these for further investigation.</p