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HIV-associated neurocognitive disorders (HANDs) are prevalent in older people living with HIV (PLWH) worldwide. HAND prevalence and incidence studies of the newly emergent population of combination antiretroviral therapy (cART)-treated older PLWH in sub-Saharan Africa are currently lacking. We aimed to estimate HAND prevalence and incidence using robust measures in stable, cART-treated older adults under long-term follow-up in Tanzania and report cognitive comorbidities.
A systematic sample of consenting HIV-positive adults aged ≥50 years attending routine clinical care at an HIV Care and Treatment Centre during March–May 2016 and followed up March–May 2017.
HAND by consensus panel Frascati criteria based on detailed locally normed low-literacy neuropsychological battery, structured neuropsychiatric clinical assessment, and collateral history. Demographic and etiological factors by self-report and clinical records.
In this cohort (n = 253, 72.3% female, median age 57), HAND prevalence was 47.0% (95% CI 40.9–53.2, n = 119) despite well-managed HIV disease (Mn CD4 516 (98-1719), 95.5% on cART). Of these, 64 (25.3%) were asymptomatic neurocognitive impairment, 46 (18.2%) mild neurocognitive disorder, and 9 (3.6%) HIV-associated dementia. One-year incidence was high (37.2%, 95% CI 25.9 to 51.8), but some reversibility (17.6%, 95% CI 10.0–28.6 n = 16) was observed.
HAND appear highly prevalent in older PLWH in this setting, where demographic profile differs markedly to high-income cohorts, and comorbidities are frequent. Incidence and reversibility also appear high. Future studies should focus on etiologies and potentially reversible factors in this setting.
The aerodynamic diameter, da, of conidia produced in vivo and in vitro by the entomopathogenic fungus Erynia neoaphidis were estimated using an impaction method. The estimated values of da for conidia produced in vivo were smaller than those produced in vitro: in vivo the values of da for primary and secondary conidia were between 16 and 18 μm (equivalent fall speed, Vs, 0·8–1·0 cm s−1); for in vitro produced conidia da values were between 28 and 31 μm (Vs, 2·4–3 cm s−1). For conidia produced by field collected cadavers the value of da, was estimated to be similar to that for conidia produced in vivo in the laboratory. The aerodynamic diameter of primary conidia of Conidiobolus obscurus (strain X39) and Zoophthora radicans (strain NW250) produced in vivo were also measured using the same method. The values of da for these two species were 45 and 17 μm (Vs, 6·2 and 0·9 cm s−1) respectively. Implications for dispersal of E. neoaphidis are discussed. The physical diameters of the test spores were measured microscopically and compared with the aerodynamic diameters.
The patterns of conidial discharge of Erynia neoaphidis were measured from three species of aphids: nettle aphid (Microlophium carnosum), grain aphid (Sitobion avenae) and pea aphid (Acyrthosiphon pisum). The effects of release height, morph of aphid and temperature on the horizontal and vertical discharge of conidia were studied. Numbers of conidia deposited in the dorsal and lateral directions were distributed with distance in truncated bell shaped patterns. Discharge distances ranged from 2 to 11 mm and half the conidia caught travelled further than 5 mm. There was little difference in the horizontal dispersal patterns of conidia when ejected from cadavers of different morphs of the same species, or from different species. The weight of infected aphids showed little correlation with discharge patterns. Values of maximum discharge distance, Dm, were generally between 6 and 9 mm. Temperature had a significant effect on conidia discharged from the dorsal surface of apterous A. pisum cadavers. Dm was greater at 18 °C than at 10 or 25 °. Vertical discharge distances for conidia released from A. pisum cadavers ranged between about 2 and 8 mm. The maximum height to which conidia were projected vertically was not affected by temperature. However, the average height tended to be greater at 18 °. Half of the conidia reached heights of about 3.5 mm while the maximum heights reached were about 8 mm. The initial speeds of conidia were estimated from measured discharge distances. The results suggest that conidia of E. neoaphidis may be ejected at speeds of about 8 ms−1.
The temporal pattern of release and dispersal of inoculum of plant and insect pathogenic fungi play an important role in the spread
of disease. Airborne concentrations of primary and secondary conidia of Erynia neoaphidis released from the rose-grain aphid
Metopolophium dirhodum were monitored at the edge of two winter wheat crops on IACR-Rothamsted Experimental Farm between
May and September in 1996 and 1997. Hourly average temperature and humidity were recorded at each spore trap site and daily
totals of rain and sunshine hours and daily average wind speed recorded about 1.6 km from the monitoring sites. No airborne
conidia were found in 1996, but large numbers were trapped at the two sites in 1997. They were present from mid-June until early
August, reaching peak concentrations on 17–18 July. Concentrations were usually highest during the night and in the early morning
(01:00–07:00 h GMT) and were generally low during the day. On the 3 days when significant numbers of conidia were caught in
the afternoon, daytime relative humidity was high (about 89%) and day-time temperature low (about 16 °C). Night-time conditions
nearly always favoured the production of conidia. This suggests day to day variation in airborne conidium concentrations may be
affected more by underlying biological factors than environmental conditions.
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