Intradural extramedullary spinal masses treated at the Wits teaching hospitals between 2014 - 2017.

BACKGROUND: Intradural extramedullary (IDEM) spinal masses are common lesions with varying histological diagnoses often associated with significant neurological deficits. This study aimed to describe the epidemiology, management and perioperative outcome of IDEM tumours seen at the teaching hospitals of the University of the Witwatersrand, Johannesburg, between 2014 and 2017. RESULTS: 92 patients were included in the study. The ages ranged from 21 to 87 years, sex ratio was M:F 1:1.4, and duration of symptoms prior to diagnosis ranged between 3 days to 18 months. Local and radicular type pain as well as motor weakness were the commonest symptoms. 67% had severe neurological deficit McCormick Grade III and IV. Schwannoma (26) Neurofibromas (21) and Meningiomas (16) and were the most frequent tumour types. Meningiomas predominantly occurred at the cranio-cervical and thoracic levels. Nerve sheath tumours were mostly found at the cervical and lumbar levels while filum terminale ependymomas occurred at the thoracolumbar area. Laminectomy was the commonest surgical approach employed, and the extent of resection varied, with total excision in half the cases. Neurological function was regained in 3 patients, deteriorated in two and was unchanged in the remainder. CONCLUSION: IDEM tumours are an important subset of spinal cord compressive lesions Presentation with severe neurological deficit is common and though resection is feasible neurological deficit remains in the vast majority. Earlier detection should improve the results of surgery.

Characterization of ultrafiltration of undiluted and diluted stored urine.

Urine ultrafiltration (UF) was studied in terms of flux, permeability, resistance and fouling. Two types of samples were used: stored urine representing the feedstock obtained from urine diversion dry toilets; and diluted stored urine representing the feedstock obtained from urinals. Three different filtration experiment sets were adopted in this study. For the first case, pressure was set in an ascending order, i.e. from 10 to 60 kPa during filtration of stored urine. For the second case, pressure was set in a descending order, i.e. from 60 to 10 kPa for the same feed stream. The third case involved filtration of diluted urine with pressure in ascending order, i.e. from 10 to 60 kPa. The results indicated that diluted urine had higher flux than undiluted urine with maximum values of 43 and 26 L·m-2·h-1 respectively. Cake formation was the dominating fouling mechanism during urine filtration with a contribution of about 90% to the total hydraulic resistance. The contribution of chemically irreversible fouling was low (-2%), unless operating from high to low pressures. Indeed, irreversible fouling appeared to be greater during the experiments starting at higher pressure. Although undiluted urine had a higher fouling potential compared to diluted urine, the specific cake resistance was higher for diluted urine, probably due to a denser cake caused by lower particle sizes in that sample. The permeate obtained after urine filtration had much lower suspended solids content compared to the feedstock, with rejections up to 99%. The concentration of the ionic species remained unchanged, and 75% of the organic compounds and dissolved solids remained in the permeate. Urine UF could then be used as pre-treatment to remove suspended solids.

Urogenital schistosomiasis in women of reproductive age and pregnant mothers in Kwale County, Kenya.

Generally, women residing in areas endemic for urinary schistosomiasis may suffer from female genital schistosomiasis which is acquired during childhood. The objective of this cross-sectional study was to estimate the prevalence and intensity of infection of Schistosoma haematobium in women of reproductive age (16-45 years) and to investigate whether S. haematobium had any effect on kidney function. A total of 394 women of known pregnancy status (158 pregnant and 236 non-pregnant) were recruited from five villages (known for their high prevalence of infection of S. haematobium) in Kwale County. Serum samples were analysed to determine levels of urea and creatinine as proxy indicators of kidney function. Data revealed that pregnant women did not, on average, have a higher prevalence or intensity of infection of urinary schistosomiasis than non-pregnant women. During pregnancy, the level of prevalence and intensity of infection of S. haematobium was highest in the first trimester (0-13 weeks), dropped in the second trimester (14-26 weeks) and rose again in the third trimester (27-40 weeks). In addition, 24.8% of women were infected with hookworm, while none were diagnosed with malaria parasites. Of 250 samples analysed for serum urea and creatinine, none had significant levels of pathology, either in pregnant or non-pregnant women. Despite World Health Organization (WHO) recommendations that pregnant women should be treated with praziquantel after the first trimester, in practice this has not been the case in many countries, including Kenya. In view of this, healthcare providers should be informed to consider treatment of pregnant women infected with schistosomiasis during antenatal visits and whenever there is mass drug administration as recommended by the WHO.

Prevalence and Intensity of Intestinal Parasitic Infections and Factors Associated with Transmission among School going Children

Objective: To determine the prevalence and intensity of intestinal parasitic infections and factors associated with transmission among primary school going children.Design: Cross-sectional descriptive study.Setting: Muthithi Location situated in Murang'a County; Kenya.Subjects: Multi-stage sampling was used to select 418 children. Stool specimens were examined using Kato-katz technique to determine the number of helminthes eggs per gram of stool and formol ether concentration technique to detect the different protozoan cysts. Data were analysed using Statistical Package format (SPSS version 20.0). Pearson's Chi-square test was used to establish the association between categorical variables. Multivariate analysis was used to determine the factors associated with the infections.Results: The study established that 53.8% (225 out of 418) were infected with one or more of intestinal parasite. Five species of helminthes were identifiedwith prevalence of 11.5%; the predominant helminth parasite identified was Ascaris lumbricoides 9.1% (38 cases). Intestinal protozoan identified in this population was Entamoeba histolytica with prevalence of 42.3% (177 cases). The factors established to be independently associated with presence of intestinal parasitic infection were: age 11-15 years P0.001; use of plain water for hand washing P0.05; eating food without spoon P0.05; consuming raw vegetables P0.001; untrimmed finger nails P0.001 and source of drinking water [river P0.001 and mixed sources (river; well and tap) P0.05]. Conclusion: This study revealed that intestinal parasites still pose a public health problem to school going children. Despite lack of school based deworming programme in this area; treatment combined with health education and other interventions in school age children is recommended as a way of controlling transmission

Dextrose boluses versus burette dextrose infusions in prevention of hypoglycemia among preterms admitted at Mulago Hospital: an open label randomized clinical trial.

BACKGROUND: Hypoglycemia is a major cause of morbidity and mortality among preterm infants and its management remains a challenge in resource limited settings. Use of dextrose infusion by the recommended infusion pumps is not feasible in our environment due to their high costs and yet the current use of mini dextrose boluses with syringes as adapted at Mulago national referral and tertiary teaching hospital has unknown efficacy in prevention of hypoglycemia. OBJECTIVE: We determined the efficacy of dextrose infusions by burettes versus two hourly dextrose boluses in prevention of hypoglycemia among preterms admitted in the first 72 hours at Special Care Unit, Mulago Hospital. METHODS: One hundred and forty preterms aged 0 to 24 hours of life were randomized to receive 10% IV dextrose either as mini boluses or by infusion using burettes in an open label clinical trial. Blood glucose was measured at 0, two hourly for next 6 hours, 6 hourly for next 12 hours and thereafter 12 hourly until end of 72 hours following admission. Primary end point was incidence of hypoglycemia (random blood sugar (RBS) < 2.6 mmol/l) which was expressed as relative risk (RR). Efficacy of the dextrose infusion was computed using 1-RR. RESULTS: From February 2012 to April 2012, 68 preterms in the bolus arm and 72 in the infusion arm were studied. Hypoglycemia was detected in 34% (48/140). The incidence of hypoglycemia in the bolus arm was 59% (40/68) compared to 11% (8/72) in the infusion arm (RR; 0.19, 95% CI; 0.09-0.37). Efficacy (1-RR) of infusion by burettes versus boluses in prevention of hypoglycemia among preterms was 0.81 (95% CI; 0.63-0.90). CONCLUSION: Continuous 10% dextrose infusion by burettes reduced the incidence of hypoglycemia by 81% in the first 72 hours of admission compared to two hourly 10% mini dextrose boluses among preterms admitted at Special Care Unit, Mulago Hospital. (ClinicalTrials.gov Identifier: NCT01688674).

Meningiomas among intracranial neoplasms in Johannesburg, South Africa: prevalence, clinical observations and review of the literature.

BACKGROUND: Worldwide there are varying reports on the prevalence of meningiomas among intracranial neoplasms. Different reports state intracranial meningiomas, gliomas or metastatic tumours as the most common tumour among intracranial neoplasms. We present our institutions' experience of patients with intracranial neoplasms and a comparison of our findings with those from the literature. OBJECTIVE: To determine the relative frequency of intracranial meningiomas among intracranial neoplasms in our environment. METHODS: Consecutive patients (151) seen at the CMJAH and CHBAH, Johannesburg, with histologically proven intracranial neoplasms over a 12 month period were analyzed. RESULTS: The commonest histological types were meningiomas, gliomas and pituitary tumours. Forty eight (31.8%) patients had histologically confirmed intracranial meningiomas during the study period, 35 (23.2%) had pituitary adenomas and 32 (21.2%) had gliomas. The mean age of the patients was 43 years with a female-to-male ratio of 1.3:1. The peak age range at presentation was in the fifth (27.1%) and sixth (26.5%) decades. CONCLUSION: The study showed that meningioma is the most common tumour among intracranial neoplasms in our environment.

Clinical practice guidelines for management of neuropathic pain: expert panel recommendations for South Africa.

Neuropathic pain (NeuP) is challenging to diagnose and manage, despite ongoing improved understanding of the underlying mechanisms. Many patients do not respond satisfactorily to existing treatments. There are no published guidelines for diagnosis or management of NeuP in South Africa. A multidisciplinary expert panel critically reviewed available evidence to provide consensus recommendations for diagnosis and management of NeuP in South Africa. Following accurate diagnosis of NeuP, pregabalin, gabapentin, low-dose tricyclic antidepressants (e.g. amitriptyline) and serotonin norepinephrine reuptake inhibitors (duloxetine and venlafaxine) are all recommended as first-line options for the treatment of peripheral NeuP. If the response is insufficient after 2 - 4 weeks, the recommended next step is to switch to a different class, or combine different classes of agent. Opioids should be reserved for use later in the treatment pathway, if switching drugs and combination therapy fails. For central NeuP, pregabalin or amitriptyline are recommended as first-line agents. Companion treatments (cognitive behavioural therapy and physical therapy) should be administered as part of a multidisciplinary approach. Dorsal root entry zone rhizotomy (DREZ) is not recommended to treat NeuP. Given the large population of HIV/AIDS patients in South Africa, and the paucity of positive efficacy data for its management, research in the form of randomised controlled trials in painful HIV-associated sensory neuropathy (HIV-SN) must be prioritised in this country.

Loop-mediated isothermal amplification test for Trypanosoma vivax based on satellite repeat DNA.

Trypanosoma vivax is major cause of animal trypanosomiasis and responsible for enormous economic burden in Africa and South America animal industry. T. vivax infections mostly run low parasitaemia with no apparent clinical symptoms, making diagnosis a challenge. This work reports the design and evaluation of a loop-mediated isothermal amplification (LAMP) test for detecting T. vivax DNA based on the nuclear satellite repeat sequence. The assay is rapid with results obtained within 35 min. The analytical sensitivity is ∼ 1 trypanosome/ml while that of the classical PCR tests ranged from 10 to 10(3)trypanosomes/ml. The T. vivax LAMP test reported here is simple, robust and has future potential in diagnosis of animal trypanosomiasis in the field.

Detection of Group 1 Trypanosoma brucei gambiense by loop-mediated isothermal amplification.

Trypanosoma brucei gambiense group 1 is the major causative agent of the Gambian human African trypanosomiasis (HAT). Accurate diagnosis of Gambian HAT is still challenged by lack of precise diagnostic methods, low and fluctuating parasitemia, and generally poor services in the areas of endemicity. In this study, we designed a rapid loop-mediated isothermal amplification (LAMP) test for T. b. gambiense based on the 3' end of the T. b. gambiense-specific glycoprotein (TgsGP) gene. The test is specific and amplifies DNA from T. b. gambiense isolates and clinical samples at 62°C within 40 min using a normal water bath. The analytical sensitivity of the TgsGP LAMP was equivalent to 10 trypanosomes/ml using purified DNA and ∼1 trypanosome/ml using supernatant prepared from boiled blood, while those of classical PCR tests ranged from 10 to 10(3) trypanosomes/ml. There was 100% agreement in the detection of the LAMP product by real-time gel electrophoresis and the DNA-intercalating dye SYBR green I. The LAMP amplicons were unequivocally confirmed through sequencing and analysis of melting curves. The assay was able to amplify parasite DNA from native cerebrospinal fluid (CSF) and double-centrifuged supernatant prepared from boiled buffy coat and bone marrow aspirate. The robustness, superior sensitivity, and ability to inspect results visually through color change indicate the potential of TgsGP LAMP as a future point-of-care test.

Tuberculosis and human immunodeficiency virus co-infections and their predictors at a hospital-based HIV/AIDS clinic in Uganda.

SETTING: Mulago Hospital, Uganda. OBJECTIVE: To evaluate the burden of TB-HIV (tuberculosis-human immunodeficiency virus) co-infections and their predictors in an urban hospital-based HIV programme. DESIGN: Prospective observational study. METHODS: Clinicians screened all patients with HIV/AIDS (acquired immune-deficiency syndrome) for previous and current TB treatment at enrolment and throughout follow-up. RESULTS: Of 10,924 patients enrolled between August 2005 and February 2009, co-prevalent TB was 157/10,924 (1.4%), which included 88/157 (56%) with TB confirmed at enrolment and 65/157 (41%) with TB diagnoses established during follow-up in whom symptoms were present at enrolment. Male sex (adjusted odds ratio [aOR] 2.3, 95%CI 1.6-3.2) and body mass index (BMI) ≤ 20 kg/m(2) (aOR 3.8, 95%CI 2.5-5.4) were associated with co-prevalent TB. Overall, 749/10,767 (7%) were diagnosed with incident TB at a higher rate among antiretroviral treatment (ART) patients (8/100 patient years of observation [PYO]) than non-ART patients (5/100 PYO, log rank P < 0.001). Female sex (adjusted hazard ratio [aHR] 1.4, 95%CI 1.2-1.7) and baseline BMI ≤ 20 (aHR 1.9, 95%CI 1.6-2.2) predicted incident TB. CONCLUSION: Routine TB screening in the HIV/AIDS care programme identified a significant number of TB-HIV co-infections among patients with and without ART, and is therefore a potential strategy to improve HIV treatment outcomes in resource-limited settings.

Transmission studies of intestinal schistosomiasis in Lake Albert, Uganda and experimental compatibility of local Biomphalaria spp.

Despite ongoing preventive chemotherapy campaigns, intestinal schistosomiasis is hyper-endemic in shoreline communities living along Lake Albert, Uganda. To provide a deeper insight into the local epidemiology of Schistosoma mansoni, a variety of field-based studies were undertaken focusing upon schistosome-snail interactions and confirmation of transmission foci. Cercarial shedding patterns of field-caught Biomphalaria spp., as identified by morphology, were hourly observed over a ten day period and showed that Biomphalaria stanleyi produced significantly more cercariae than Biomphalaria sudanica. Peak production times in both species were between 12.00 and 14.00h indicating greatest infection risk from lake water exposure is during the early afternoon. Laboratory-bred snails were exposed to locally hatched miracidia and susceptibility of Biomphalaria spp. was confirmed experimentally. Biomphalaria stanleyi was a more permissive host. After ascertaining appropriate conditions for infection of laboratory mice, 28 groups of between 5 and 6 naïve mice were placed in floatation cages at four suspected shoreline transmission sites for a 30 minute period of exposure. Eight weeks later, mice (n=142) were culled and S. mansoni adult worms were retrieved from 10 animals. Taken as a whole, these observations highlight the local importance of B. stanleyi in transmission of intestinal schistosomiasis and clearly demonstrate the risk of infection on the Lake Albert shoreline. To mitigate this risk local environmental modification(s), i.e. improvement in sanitation and hygiene and control of snail populations, is needed to bolster the impact of chemotherapy-based interventions.

Effects of enforcement of the traffic act on injury severity among patients admitted at the Rift Valley Provincial General Hospital, Nakuru.

BACKGROUND: The Traffic Act was enforced in Kenya from 1st February 2004. Systematic evaluations of the effects of this enforcement on injury severity are unavailable. OBJECTIVE: To compare injury severity among victims of public service vehicle (PSV) crashes in the periods one year before and one year after the enforcement of the Traffic Act. DESIGN: A retrospective pre and post-intervention survey. SETTING: Rift Valley Provincial General Hospital, Nakuru. RESULTS: There were no changes in injury severity levels among the sampled patients before and after the enforcement of the Traffic Act (Most Absolute difference = 0.087, Kolmogorov-Smimov Z = 0.722, p > 0.05). The patients stayed in hospital for a median of three days in both policy periods. The mean age of the patients was 31.49 years (SD = 14.58) while three quarters of the patients were males. The age and sex profiles of the admitted patients did not change with the enforcement of the Traffic Act. CONCLUSION: The enforcement of the Traffic Act did not have any effect on injury severity among admitted PSV crash victims. Measures to lessen the burden of road traffic injury deserve greater attention.

Hepatosplenomegaly associated with chronic malaria exposure: evidence for a pro-inflammatory mechanism exacerbated by schistosomiasis.

In sub-Saharan Africa, chronic hepatosplenomegaly, with palpable firm/hard organ consistency, is common, particularly among school-aged children. This morbidity can be caused by long-term exposure to malaria, or by Schistosoma mansoni, and it is exacerbated when these two occur together. Although immunological mechanisms probably underlie the pathogenic process, these mechanisms have not been identified, nor is it known whether the two parasites augment the same mechanisms or induce unrelated processes that nonetheless have additive or synergistic effects. Kenyan primary schoolchildren, living in a malaria/schistosomiasis co-transmission area, participated in cross-sectional parasitological and clinical studies in which circulating immune modulator levels were also measured. Plasma IL-12p70, sTNF-RII, IL-10 and IL-13 levels correlated with relative exposure to malaria, and with hepatosplenomegaly. Soluble-TNF-RII and IL-10 were higher in children infected with S. mansoni. Hepatosplenomegaly caused by chronic exposure to malaria was clearly associated with increased circulating levels of pro-inflammatory mediators, with higher levels of regulatory modulators, and with tissue repair cytokines, perhaps being required to control the inflammatory response. The higher levels of regulatory modulators amongst S. mansoni infected children, compared to those without detectable S. mansoni and malarial infections, but exposed to malaria, suggest that S. mansoni infection may augment the underlying inflammatory reaction.

Structure of some East African Glossina fuscipes fuscipes populations.

Glossina fuscipes fuscipes Newstead 1910 (Diptera: Glossinidae) is the primary vector of human sleeping sickness in Kenya and Uganda. This is the first report on its population structure. A total of 688 nucleotides of mitochondrial ribosomal 16S2 and cytochrome oxidase I genes were sequenced. Twenty-one variants were scored in 79 flies from three geographically diverse natural populations. Four haplotypes were shared among populations, eight were private and nine were singletons. The mean haplotype and nucleotide diversities were 0.84 and 0.009, respectively. All populations were genetically differentiated and were at demographic equilibrium. In addition, a longstanding laboratory culture originating from the Central African Republic (CAR-lab) in 1986 (or before) was examined. Haplotype and nucleotide diversities in this culture were 0.95 and 0.012, respectively. None of its 27 haplotypes were shared with the East African populations. A first approximation of relative effective population sizes was Uganda > CAR-lab > Kenya. It was concluded that the structure of G. f. fuscipes populations in East Africa is localized.

African trypanosomiasis: sensitive and rapid detection of the sub-genus Trypanozoon by loop-mediated isothermal amplification (LAMP) of parasite DNA.

Control of human African trypanosomiasis (HAT) is dependent on accurate diagnosis and treatment of infected patients. However, sensitivities of tests in routine use are unsatisfactory, due to the characteristically low parasitaemias in naturally infected individuals. We have identified a conserved sequence in the repetitive insertion mobile element (RIME) of the sub-genus Trypanozoon and used it to design primers for a highly specific loop-mediated isothermal amplification (LAMP) test. The test was used to analyse Trypanozoon isolates and clinical samples from HAT patients. The RIME LAMP assay was performed at 62 degrees C using real-time PCR and a water bath. DNA amplification was detectable within 25min. All positive samples detected by gel electrophoresis or in real-time using SYTO-9 fluorescence dye could also be detected visually by addition of SYBR Green I to the product. The amplicon was unequivocally confirmed through restriction enzyme NdeI digestion, analysis of melt curves and sequencing. The analytical sensitivity of the RIME LAMP assay was equivalent to 0.001 trypanosomes/ml while that of classical PCR tests ranged from 0.1 to 1000 trypanosomes/ml. LAMP detected all 75 Trypanozoon isolates while TBR1 and two primers (specific for sub-genus Trypanozoon) showed a sensitivity of 86.9%. The SRA gene PCR detected 21 out of 40 Trypanosoma brucei rhodesiense isolates while Trypanosoma gambiense-specific glycoprotein primers (TgsGP) detected 11 out of 13 T. b. gambiense isolates. Using clinical samples, the LAMP test detected parasite DNA in 18 out of 20 samples which included using supernatant prepared from boiled blood, CSF and direct native serum. The sensitivity and reproducibility of the LAMP assay coupled with the ability to detect the results visually without the need for sophisticated equipment indicate that the technique has strong potential for detection of HAT in clinical settings. Since the LAMP test shows a high tolerance to different biological substances, determination of the appropriate protocols for processing the template to make it a user-friendly technique, prior to large scale evaluation, is needed.

Patterns of genetic diversity and differentiation in the tsetse fly Glossina morsitans morsitans Westwood populations in East and southern Africa.

Genetic diversity and differentiation within and among nine G. morsitans morsitans populations from East and southern Africa was assessed by examining variation at seven microsatellite loci and a mitochondrial locus, cytochrome oxidase (COI). Mean COI diversity within populations was 0.63+/-0.33 and 0.81 taken over all populations. Diversities averaged over microsatellite loci were high (mean number of alleles/locus>or=7.4; mean HE>or=65%) in all populations. Diversities averaged across populations were greater in East Africa (mean number of alleles=22+/-2.6; mean he=0.773+/-0.033) than in southern Africa (mean number of alleles=18.7+/-4.0; mean he=0.713+/-0.072). Differentiation among all populations was highly significant (RST=0.25, FST=0.132). Nei's Gij statistics were 0.09 and 0.19 within regions for microsatellites and mitochondria, respectively; between regions, Gij was 0.14 for microsatellites and 0.23 for mitochondria. GST among populations was 0.23 for microsatellite loci and 0.40 for mitochondria. The F, G and R statistics indicate highly restricted gene flow among G. m. morsitans populations separated over geographic scales of 12-917 km.

Visual deterioration 1(1/2) years after wrapping an un-clippable anterior communicating artery aneurysm: report of a case and review of the literature regarding opto-chiasmatic arachnoiditis.

OBJECTIVE: Optochiasmatic arachnoiditis (OCA) is a serious complication that can occur after wrapping of aneurysms in the proximity of the optic pathways. This paper seeks to illustrate one such case with a view to drawing attention to the dangers of this practice. METHOD: Single case report and review of the literature. RESULTS: The clinical and radiological features of OCA are presented and discussed, which in this patient involved failing visual acuity as well as an inflammatory mass of the suprasellar area with oedema of the optic apparatus. CONCLUSION: Optochiasmatic arachnoiditis and its attendant visual morbidity is a serious condition. In the setting described, it arose as a result of wrapping an unclippable aneurysm. The tide of aneurysm management has turned, and presently more and more of them are being obliterated by endovascular techniques. Among other benefits, this reduces the likelihood of such complications as OCA.

New polymorphic microsatellites in Glossina pallidipes (Diptera: Glossinidae) and their cross-amplification in other tsetse fly taxa.

We report the development and characterization of three new microsatellite markers in the tsetse fly, Glossina pallidipes (Diptera: Glossinidae). Fifty-eight alleles were scored in 192 individuals representing six natural populations. Allelic diversity ranged from 9 to 28 alleles per locus (mean 19.3 +/- 5.5). Averaged across loci, observed heterozygosity was 0.581 +/- 0.209, and expected heterozygosity was 0.619 +/- 0.181. Cross-species amplifications of the G. pallidipes loci in other tsetse fly taxa are reported.

Glossina swynnertoni (Diptera: Glossinidae): effective population size and breeding structure estimated by mitochondrial diversity.

Nucleotide diversity was examined at mitochondrial COI and r16S2 loci in eight Glossina swynnertoni Austen collections from northern Tanzania and from a culture maintained by the International Atomic Energy Agency. Eighteen composite haplotypes were observed among 149 flies, two of which were common to all samples and 10 were private. Mean haplotype diversity was 0.59 and nucleotide diversity was 0.0013. There were excess singular haplotypes and mutation-drift disequilibrium suggesting that populations had experienced an earlier bottleneck and subsequent expansion. Factorial correspondence analysis showed that haplotype frequencies varied much more temporally (G ST=0.18) than spatially (G ST=0.04). The estimate of effective population size N e in Tarangire was a harmonic mean approximately 50 reproductive flies averaged over approximately 47 generations. The mean rate of gene flow was estimated to be approximately 5+/-1 reproducing females per generation but inflated because of mutation-drift disequilibrium arising from likely earlier bottlenecks.

Microgeographical breeding structure of the tsetse fly, Glossina pallidipes in south-western Kenya.

The origins of extant Glossina pallidipes Austen (Diptera: Glossinidae) populations in the ecologically well-studied Lambwe and Nguruman valleys in Kenya are controversial because populations have recovered after seemingly effective attempts to achieve high levels of control. The microgeographical breeding structure of the tsetse fly, G. pallidipes, was investigated by analysing spatial and temporal variation at eight microsatellite loci to test hypotheses about endemism and immigration. Samples were obtained at seasonal intervals from trap sites separated by 200 m to 14 km and arranged into blocks. G. pallidipes populations nearest to Lambwe and Nguruman also were sampled. Spatial analysis indicated that genetic differentiation by genetic drift was much less among trapping sites within Lambwe and Nguruman (F(ST) < or = 0.049) than between them (F(ST) = 0.232). F(ST) between Serengeti and Nguruman was 0.16 and F(ST) between Kodera Forest and Lambwe was 0.15. The genetic variance in G. pallidipes explained by dry and wet seasons (0.33%) was about one-fifth the variance among collection dates (1.6%), thereby indicating reasonable temporal stability of genetic variation. Gene frequencies in Kodera and Serengeti differed greatly from Lambwe and Nguruman, thereby falsifying the hypothesis that Lambwe and Nguruman were repopulated by immigrants. Harmonic mean effective (= breeding) population sizes were 180 in Lambwe and 551 in Nguruman. The genetic data suggest that G. pallidipes in Lambwe and Nguruman have been endemic for long intervals.