Structural motifs of pre-nucleation clusters

Structural motifs of pre-nucleation clusters prepared in single, optically levitated supersaturated aqueous aerosol microparticles containing CaBr2 as a model system are reported. Cluster formation is identified by means of X-ray absorption in the Br K-edge regime. The salt concentration beyond the saturation point is varied by controlling the humidity in the ambient atmosphere surrounding the 15–30 μm microdroplets. This leads to the formation of metastable supersaturated liquid particles. Distinct spectral shifts in near-edge spectra as a function of salt concentration are observed, in which the energy position of the Br K-edge is red-shifted by up to 7.1 ± 0.4 eV if the dilute solution is compared to the solid. The K-edge positions of supersaturated solutions are found between these limits. The changes in electronic structure are rationalized in terms of the formation of pre- nucleation clusters. This assumption is verified by spectral simulations using first-principle density functional theory and molecular dynamics calculations, in which structural motifs are considered, explaining the experimental results. These consist of solvated CaBr2 moieties, rather than building blocks forming calcium bromide hexahydrates, the crystal system that is formed by drying aqueous CaBr2 solutions

Status of Schistosoma mansoni prevalence and intensity of infection in geographically apart endemic localities of Ethiopia: A comparison

BACKGROUND: Schistosomiasis is one of the chronic and neglected tropical diseases affecting rural communities. Heavy infections contribute to anemia and can retard children's growth, physical activity and cognitive function. This study was conducted in order to determine the prevalence, intensity and variation of Schistosoma mansoni infection among human subjects in geographically apart localities. The prevalence and intensity of Schistosoma mansoni infection was assessed in three geographically apart endemic areas of Ethiopia from May to August 2010 through cross-sectional approach.METHODS: A total of 1073 individuals (528 males and 545 females) were found eligible for the study. Their age ranged from 5-60 years with mean age of 11 years in Wondo Genet, 22 years in Kemissie and 24 years in Sille-Elgo. Small plastic sheets were distributed to the study participants and sizable stool specimens were collected and examined using Kato-Katz method (41.7mg template).RESULT: The prevalence of Schistosoma mansoni infection among the study participants in Kemissie, Wondo Genet and Sille-Elgo was 89.6%, 59.9%, and 31.6%, respectively. The highest geometric mean of egg per gram of stool for Kemissie, Wondo Genet and Sille-Elgo was, 5208 and 346, 8472 and 252, 3960 and 91, respectively.CONCLUSION: It was observed that there was comparable variation in the prevalence and intensity of infection among the study localities. Moreover, it is indicated that S. mansoni is still an ongoing public health problem which requires integrated intervention activities in the country.KEYWORDS: Schistosoma mansoni; intensity of infection; geographic variation; Ethiopi

Status of onchocerciasis in Teppi area, Southwestern Ethiopia, after four years of annual community-directed treatment with ivermectin

Background: Information on the impact of annual community-directed treatment with ivermectin (CDTI) on the prevalence and intensity of onchocerciasis as well as its transmission following years of repeated ivermectin distribution is vital to monitor the impact of the control efforts.Objective: To determine the status of the prevalence and intensity of onchocerciasis after four years of ivermectin distribution in Teppi area.Methods: Skin snips were obtained from 390 study participants and kept in physiological saline at room temperature for 24 hours. The emerged microfilariae were counted under 10x microscope objective. The skin snips were weighed and the microfilarial load was expressed as the arithmetic mean of two skin snips per mg of skin snip.Results: Out of the total 390 examined subjects, 87 (22.3%) were found to be positive for microfilaridermia. Significant differences in the prevalence and microfilarial load of the disease were not found among untreated and treated subjects (p > 0.05). Significant reductions of the prevalence (25.5%) and intensity of infection (0.08 – 8mf, mean 1.3) were found compared to prevalence (81%) and intensity of infection ( 0-855, mean 33 ± 5.6) reported before the initiation of the CDTI programme in the study area.Conclusion: The overall results of the study showed a high reduction both in the prevalence and intensity of infection compared to prevalence and intensity of the disease before the initiation of the CDTI programme in the study area. Nevertheless, continued assessment of the long-term impact of repeated annual CDTI programme on onchocerciasis and identification of factors that could affect the sustainability of the programme in various CDTI areas of Ethiopia, could contribute towards the effective control of the programme. [Ethiop. J. Health Dev. 2010;24(1):51-56

Comparative efficacy of albendazole and three brands of mebendazole in the treatment of ascariasis and trichuriasis

Objective: To evaluate the comparative efficacy of 400 mg albendazole (Smith Kline Beecham) as a single dose and three brands of mebendazole (Janssen, Unibios and East African Pharmaceuticals) at doses of 100 mg twice a day for three consecutive days in the treatment of single or mixed infections with Ascaris lumbricoides and or Trichuris trichiura in four treatment groups of school children. Design: Randomized trial. Setting: Wondo-Genet, southern Ethiopia. Subjects: School children, aged six to nineteen years. Results: The percentage cure rate and egg reduction rate obtained with albendazole and mebendazole from the three brands were not significantly different in the treatment of ascariasis. However, significant differences were found among the percentage cure rates and egg reduction rates of the four treatment groups in the treatment of trichuriasis. Comparatively, high cure rate (89.8%) and egg reduction rate (99.1%) were observed in vermox (Janssen) treated group followed by Unibios (India) treated group (53.3% and 96.53% cure and egg reduction rates, respectively), whereas low cure rate (17.1%) and egg reduction rate (69.8%) were seen in the albendazole treated group. Conclusion: The results of this study suggest that in areas of single or mixed infections with Trichuris trichiura and/or Ascaris lumbricoides are common public health problems and where laboratory facilities are not available to make parasite identification, mebendazole (particularly vermox, a product of Janssen laboratory) would be the drug of choice to treat trichuriasis and ascariasis. However, either mebendazole from the different brands or albendazole is effective in the treatment of ascariasis in areas where trichuriasis is not prevalent. East African Medical Journal Vol. 81 No. 3 March 2004: 134-13

The burden of neglected tropical diseases in Ethiopia, and opportunities for integrated control and elimination

Background: Neglected tropical diseases (NTDs) are a group of chronic parasitic diseases and related conditions that are the most common diseases among the 2·7 billion people globally living on less than US$2 per day. In response to the growing challenge of NTDs, Ethiopia is preparing to launch a NTD Master Plan. The purpose of this review is to underscore the burden of NTDs in Ethiopia, highlight the state of current interventions, and suggest ways forward. Results: This review indicates that NTDs are significant public health problems in Ethiopia. From the analysis reported here, Ethiopia stands out for having the largest number of NTD cases following Nigeria and the Democratic Republic of Congo. Ethiopia is estimated to have the highest burden of trachoma, podoconiosis and cutaneous leishmaniasis in sub-Saharan Africa (SSA), the second highest burden in terms of ascariasis, leprosy and visceral leishmaniasis, and the third highest burden of hookworm. Infections such as schistosomiasis, trichuriasis, lymphatic filariasis and rabies are also common. A third of Ethiopians are infected with ascariasis, one quarter is infected with trichuriasis and one in eight Ethiopians lives with hookworm or is infected with trachoma. However, despite these high burdens of infection, the control of most NTDs in Ethiopia is in its infancy. In terms of NTD control achievements, Ethiopia reached the leprosy elimination target of 1 case/10,000 population in 1999. No cases of human African trypanosomiasis have been reported since 1984. Guinea worm eradication is in its final phase. The Onchocerciasis Control Program has been making steady progress since 2001. A national blindness survey was conducted in 2006 and the trachoma program has kicked off in some regions. Lymphatic Filariasis, podoconiosis and rabies mapping are underway. Conclusion: Ethiopia bears a significant burden of NTDs compared to other SSA countries. To achieve success in integrated control of NTDs, integrated mapping, rapid scale up of interventions and operational research into co implementation of intervention packages will be crucial

Current status of intestinal Schistosomiasis and soiltransmitted helminthiasis among primary school children in Adwa Town, Northern Ethiopia

Background: Epidemiological baseline information on the prevalence and intensity of parasitic infections in a given locality is a prerequisite for development and evaluation of sound control strategies.Objective: To determine the current status of schistosomiasis and soil-transmitted helminthiasis among primary school children in Adwa Town, northern Ethiopia.Methods: A cross-sectional epidemiological study was carried out in eight primary schools in Adwa Town between October and November 2007. Fecal samples of 386 school children in the age group 7-18 were collected andmicroscopically examined using the Kato-Katz and formol-ether concentration methods. A questionnaire was used to identify determinants for Schistosoma mansoni and soil-transmitted helminth infections.Results: The most prevalent intestinal parasitic infection among primary school children in Adwa Town as determined by Kato-Katz (58.7%) and formol ether concentration (60.6%) methods was intestinal schistosomiasis, with an overall intensity of 95.8 eggs per gram of stool. The prevalence of S. mansoni infection was higher in males (70.7%) than in females (57%), as determined by both methods. Less common parasites observed included Ascaris lumbricoides, hookworm species, Hymenolepis nana, Strongyloides stercoralis, and Entamoeba histolytica/dispar.Conclusion: The residents of Adwa Town represent a high-risk community with respect to intestinal schistosomiasis. Hence, mass praziquantel administration to school-age children and all adults considered to be at risk is required once a year until the level of infection falls below the level of public health importance. There is also a need to supplement chemotherapy with other measures such as environmental sanitation and health education to make the impact of chemotherapy sustainable

Interpreting ambiguous ‘trace’ results in Schistosoma mansoni CCA Tests: Estimating sensitivity and specificity of ambiguous results with no gold standard

Background The development of new diagnostics is an important tool in the fight against disease. Latent Class Analysis (LCA) is used to estimate the sensitivity and specificity of tests in the absence of a gold standard. The main field diagnostic for Schistosoma mansoni infection, Kato-Katz (KK), is not very sensitive at low infection intensities. A point-of-care circulating cathodic antigen (CCA) test has been shown to be more sensitive than KK. However, CCA can return an ambiguous ‘trace’ result between ‘positive’ and ‘negative’, and much debate has focused on interpretation of traces results. Methodology/Principle findings We show how LCA can be extended to include ambiguous trace results and analyse S. mansoni studies from both Côte d’Ivoire (CdI) and Uganda. We compare the diagnostic performance of KK and CCA and the observed results by each test to the estimated infection prevalence in the population. Prevalence by KK was higher in CdI (13.4%) than in Uganda (6.1%), but prevalence by CCA was similar between countries, both when trace was assumed to be negative (CCAtn: 11.7% in CdI and 9.7% in Uganda) and positive (CCAtp: 20.1% in CdI and 22.5% in Uganda). The estimated sensitivity of CCA was more consistent between countries than the estimated sensitivity of KK, and estimated infection prevalence did not significantly differ between CdI (20.5%) and Uganda (19.1%). The prevalence by CCA with trace as positive did not differ significantly from estimates of infection prevalence in either country, whereas both KK and CCA with trace as negative significantly underestimated infection prevalence in both countries. Conclusions Incorporation of ambiguous results into an LCA enables the effect of different treatment thresholds to be directly assessed and is applicable in many fields. Our results showed that CCA with trace as positive most accurately estimated infection prevalence

Sensitivity and Specificity of Multiple Kato-Katz Thick Smears and a Circulating Cathodic Antigen Test for Schistosoma mansoni Diagnosis Pre- and Post-repeated-Praziquantel Treatment

Two Kato-Katz thick smears (Kato-Katzs) from a single stool are currently recommended for diagnosing Schistosoma mansoni infections to map areas for intervention. This ‘gold standard’ has low sensitivity at low infection intensities. The urine point-of-care circulating cathodic antigen test (POC-CCA) is potentially more sensitive but how accurately they detect S. mansoni after repeated praziquantel treatments, their suitability for measuring drug efficacy and their correlation with egg counts remain to be fully understood. We compared the accuracies of one to six Kato-Katzs and one POC-CCA for the diagnosis of S. mansoni in primary-school children who have received zero to ten praziquantel treatments. We determined the impact each diagnostic approach may have on monitoring and evaluation (M&E) and drug-efficacy findings

Transmission of Schistosoma mansoni in Tikur Wuha area, Southern Ethiopia

Background: Although the epidemiology of schistosomiasis is well established and the disease distribution has also been mapped in Ethiopia, discovery of new foci has continuously been reported.Objectives: The objective of this study was to assess the establishment of transmission of schistosomiasis mansoni in Tikur Wuha area, southern Ethiopia.Methods: A cross-sectional epidemiological study involving 375 school children in Tikur Wuha Elementary School was conducted in December 2007 and January 2008. Stool specimens were collected and microscopically examined using Kato-Katz method. Snail survey was also conducted using scoop in Tikur Wuha River and littoral zone of Lake Awassa on the side of Tikur Wuha Kebele (administrative unit). The snails collected were checked for trematode infection by shedding. Laboratory-bred mice were exposed to schistosome cercariae and definite identification of the schistosome was made using eggs and adult worm morphology.Results: The prevalence and intensity of schistosomiasis mansoni was 12% and 69 eggs per gram (epg) of stool, respectively. Biomphalaria sudanica collected in Tikur Wuha River shed schistosome cercariae. Adult S. mansoni worms were harvested from laboratory-bred mice after 6 weeks of laboratory maintenance.Conclusion: The prevalence and intensity of schistosomiasis mansoni among school children was low and the area represents low-risk community. The finding of S. mansoni infected young children, the collection of B. sudanica infected with schistosome cercariae, and the establishment of infection in lab-bred mice all confirmed the transmissionof schistosomiasis mansoni in Tikur Wuha area. Appropriate intervention measures need to be in place to reduce morbidity and transmission of intestinal schistosomiasis in the area

Performance of CareStart™ Malaria Pf/Pv Combo test for the diagnosis of Plasmodium falciparum and Plasmodium vivax infections in the Afar Region, North East Ethiopia

Background: CareStart™ Malaria Pf/Pv Combo test has shown encouraging results for the diagnosis of P. falciparum and P. vivax infections in Ethiopia. Nevertheless, the performance of the test could be affected by different factors like gene polymorphisms, excess heat and humidity. Hence, evaluation of the performance of the test in different settings in Ethiopia is vital for the routine diagnosis of malaria.Objective: To evaluate the diagnostic performance of CareStartTM Malaria Pf/Pv Combo test for the diagnosis of P. falciparum and P. vivax infections in the Afar Region, Northeast Ethiopia.Methods: Finger prick blood samples were collected from a total of 1092 patients who had malaria symptoms and visited three different health facilities in the Afar Region. Giemsa-stained thin and thick blood smears were prepared and microscopically examined under 100 × magnifications for Plasmodium species identification and determination of parasitaemia. CareStart Malaria Pf/Pv Combo test was also performed as per the manufacturer's instructions. The sensitivity and the specificity of the test was determined using microscopy as gold standard.Results: The sensitivity and specificity of the test were 98.5% and 98.0% respectively, with a positive predictive value (PPV) of 91.7% and a negative predictive value (NPV) of 99.7% for the diagnosis of P. falciparum infection. The corresponding sensitivity and specificity for the diagnosis of P. vivax infection were 100% and 99.6% respectively, with PPV and NPV of 86.2% and 100%, respectively.Conclusion: The results of this study revealed high sensitivity and specificity of CareStartTM Malaria Pf/Pv Combo test for the diagnosis of both P. falciparum and P. vivax infections in the study area, though additional study may be needed in the most peripheral hottest areas of the region. [Ethiop. J. Health Dev. 2011;25(3):206-211