Department of Biological sciences

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Browsing Department of Biological sciences by Author "Asio, Santa Maria"

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    Analysis of the 24-h microfilarial periodicity of Mansonella perstans
    (Springerlink: Parasitology Research, 2008-12-24) Asio, Santa Maria; Simonsen, Paul E.; Onapa, Ambrose W.
    The Mansonella perstans microfilarial (mf) periodicity in peripheral blood was analysed in a group of 32 healthy individuals from an endemic community in Uganda. The majority of individuals had maximum mf intensity during the first and minimum during the last 12 h of the day. Mean mf ratios (i.e. time-specific counts in relation to mean count for the individual) indicated a weak but significant diurnal periodicity with peak intensity around 0800 h. Trigonometric analysis of the ratios, assuming a harmonic wave pattern of periodicity, gave a periodicity index of 11.1 and a peak time of 0645 h. The higher mf intensities in the early morning appeared to coincide with the preferred biting hour of the vectors. The observed weak pattern of mf periodicity indicates that the sampling time of blood specimens for diagnosis will have only minor effect on diagnostic sensitivity.
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    How water exchange and seasonality affect the eutrophication of Murchison bay, lake Victoria
    (Elsevier: Limnologica, 2015-07) Luyiga, Suzan; Haande, Sigrid; Semyalo, Ronald P.; Kizito, Yusuf S.; Miyingo-Kezimbira, Anne; Brettum, Pål; Solheim, Anne Lyche; Odong, Robinson; Asio, Santa Maria; Jensen, Knut Helge; Larsson, Petter
    Murchison Bay in the Northern part of Lake Victoria has for decades received a daily wastewater load of 0.2% of its volume from Kampala City, through the Nakivubo channel. In spite of this, the Water Treatment Works abstracts raw water from this bay and has been able to produce drinking water of sufficient quality for the capital. This study monitored various physical−chemical components within the bay during 2000−2003 to understand the processes responsible for the acceptable quality of raw water. Four sampling stations were located along a transect from the channel mouth towards the open lake. Results showed that the wastewater did not accumulate in the bay, instead was already strongly diluted 2.5 km from the channel mouth. This caused an abrupt reduction in conductivity and the concentrations of the nutrients total phosphorus (Tot-P), orthophosphate (PO4-P) and total nitrogen (Tot-N). Inshore−offshore exchange of water was mediated by flows from daily and sub-daily water level fluctuations and wind-driven currents. As a daily average, 2% of the Murchison Bay flowed in and out and the incoming wastewater was diluted 9.7 times. During the dry season from June to August (D2), when the weather was influenced by the south-east monsoon, the thermal stratification in the main lake disappeared and cooler and deoxygenated water from deeper depths entered the bay influencing its water quality. The daily flushing of water in and out of the bay due to water level variation was identified as the main factor diluting the bay water.
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    Mansonella perstans filariasis in Africa
    (Elsevier: Acta Tropica, 2011-09) Simonsen, Paul E.; Onapa, Ambrose W.; Asio, Santa Maria
    Mansonella perstans is a vector-borne human filarial nematode, transmitted by tiny blood-sucking flies (biting midges). It is widespread in many parts of Sub-Saharan Africa and also occurs in parts of Central and South America. Despite the commonness of this parasite very few studies have been carried out on its epidemiology and on the morbidity resulting from it, and only few thorough drug trials have been conducted to look for effective and suitable drugs and drug regimens for treatment and control. Here, we review currently available knowledge on M. perstans infections in Africa, including documented aspects of biology, vectors, transmission, diagnosis, epidemiology, morbidity and treatment. It is concluded that there is an urgent need for more research on this widespread but greatly neglected infection in order to properly assess its public health significance and as a background for identifying and recommending optimal means and strategies for treatment and control.
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    Mansonella perstans filariasis in Uganda: patterns of microfilaraemia and clinical manifestations in two endemic communities
    (Oxford Academic: Transactions of The Royal Society of Tropical Medicine and Hygiene, 2009-03-01) Asio, Santa Maria; Simonsen, Paul E.; Onapa, Ambrose W.
    Surveys for Mansonella perstans infection and potentially related clinical manifestations were undertaken in two endemic communities in Mukono and Luwero districts of Uganda where no other human filarial infections are transmitted. A sensitive and accurate counting chamber method was used for quantifying microfilaraemia in 100 μl of finger-prick blood. Among 575 and 991 examined individuals aged ≥1 year in the two communities, the overall microfilariae (mf) prevalence was significantly higher in Mukono (76.5%) than in Luwero (57.7%). As early as age 1–4 years, 40.6% and 20.5% of the children were mf-positive. Prevalences increased rapidly with increasing age to reach 89.2% and 81.4% in the 15–19 years age group and then remained high in subsequent age groups. The geometric mean mf intensity among mf-positive individuals was slightly higher in the Mukono community (32.4 mf/100 μl) than in the Luwero community (29.9 mf/100 μl), and this parameter increased with age in both communities. No obvious associations were observed between various clinical parameters and M. perstans microfilaraemia in any of the study communities. The observed patterns of microfilaraemia and the lack of obvious visible clinical manifestations suggest that the host's regulatory responses are downregulated in M. perstans infections. [ClinicalTrials.gov identifier:
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    A randomised, double-blind field trial of ivermectin alone and in combination with albendazole for the treatment of Mansonella perstans infections in Uganda
    (Oxford Academic: Transactions of The Royal Society of Tropical Medicine and Hygiene, 2009-03-01) Asio, Santa Maria; Simonsen, Paul E.; Onapa, Ambrose W.
    The effect of a single dose of ivermectin alone (150–200 μg/kg body weight) or in combination with albendazole (total of 400 mg) in Mansonella perstans infection was assessed in a randomised, double-blind field trial in two endemic communities in Mukono and Luwero districts of Uganda. No side effects were observed or reported during the first 7 days after treatment. The effect on microfilaraemia was analysed among individuals with ≥20 microfilariae (mf) per 100 μl of blood at baseline, who took the treatment and who attended follow-up examinations at 6 months and 12 months after treatment (48 and 46 in Mukono and 48 and 40 in Luwero for the ivermectin and combination treatment, respectively). In both communities, the combination treatment appeared slightly more effective than ivermectin alone, but the difference was not statistically significant. Both drug regimens were more effective in Luwero than in Mukono, probably owing to different diets in the two areas. However, in general both treatment regimens in both communities had limited effect on microfilarial intensities, and only one individual (given combination treatment in Luwero) was mf-negative at 6 months and 12 months after treatment. [ClinicalTrials.gov identifier