scholarly journals Rainfall Trends and Malaria Occurrences in Limpopo Province, South Africa

2019 ◽  
Vol 16 (24) ◽  
pp. 5156 ◽  
Author(s):  
Abiodun Adeola ◽  
Katlego Ncongwane ◽  
Gbenga Abiodun ◽  
Thabo Makgoale ◽  
Hannes Rautenbach ◽  
...  
Keyword(s):  
Time Series ◽  
Malaria Transmission ◽  
Daily Rainfall ◽  
Limpopo Province ◽  
P Value ◽  
Total Rainfall ◽  
Rainfall Trends ◽  
Monthly Total ◽  
Vhembe District ◽  
Spearman’S Correlation

This contribution aims to investigate the influence of monthly total rainfall variations on malaria transmission in the Limpopo Province. For this purpose, monthly total rainfall was interpolated from daily rainfall data from weather stations. Annual and seasonal trends, as well as cross-correlation analyses, were performed on time series of monthly total rainfall and monthly malaria cases in five districts of Limpopo Province for the period of 1998 to 2017. The time series analysis indicated that an average of 629.5 mm of rainfall was received over the period of study. The rainfall has an annual variation of about 0.46%. Rainfall amount varied within the five districts, with the northeastern part receiving more rainfall. Spearman’s correlation analysis indicated that the total monthly rainfall with one to two months lagged effect is significant in malaria transmission across all the districts. The strongest correlation was noticed in Vhembe (r = 0.54; p-value = <0.001), Mopani (r = 0.53; p-value = <0.001), Waterberg (r = 0.40; p-value =< 0.001), Capricorn (r = 0.37; p-value = <0.001) and lowest in Sekhukhune (r = 0.36; p-value = <0.001). Seasonally, the results indicated that about 68% variation in malaria cases in summer—December, January, and February (DJF)—can be explained by spring—September, October, and November (SON)—rainfall in Vhembe district. Both annual and seasonal analyses indicated that there is variation in the effect of rainfall on malaria across the districts and it is seasonally dependent. Understanding the dynamics of climatic variables annually and seasonally is essential in providing answers to malaria transmission among other factors, particularly with respect to the abrupt spikes of the disease in the province.

scholarly journals Parasite genetic diversity reflects continued residual malaria transmission in Vhembe District, a hotspot in the Limpopo Province of South Africa

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Hazel B. Gwarinda ◽  
Sofonias K. Tessema ◽  
Jaishree Raman ◽  
Bryan Greenhouse ◽  
Lyn-Marié Birkholtz
Keyword(s):  
South Africa ◽  
Genetic Diversity ◽  
Malaria Transmission ◽  
Limpopo Province ◽  
Parasite Population ◽  
High Genetic Diversity ◽  
Management Interventions ◽  
Imported Cases ◽  
Study Sites ◽  
Vhembe District

Abstract Background South Africa aims to eliminate malaria transmission by 2023. However, despite sustained vector control efforts and case management interventions, the Vhembe District remains a malaria transmission hotspot. To better understand Plasmodium falciparum transmission dynamics in the area, this study characterized the genetic diversity of parasites circulating within the Vhembe District. Methods A total of 1153 falciparum-positive rapid diagnostic tests (RDTs) were randomly collected from seven clinics within the district, over three consecutive years (2016, 2017 and 2018) during the wet and dry malaria transmission seasons. Using 26 neutral microsatellite markers, differences in genetic diversity were described using a multiparameter scale of multiplicity of infection (MOI), inbreeding metric (Fws), number of unique alleles (A), expected heterozygosity (He), multilocus linkage disequilibrium (LD) and genetic differentiation, and were associated with temporal and geospatial variances. Results A total of 747 (65%) samples were successfully genotyped. Moderate to high genetic diversity (mean He = 0.74 ± 0.03) was observed in the parasite population. This was ascribed to high allelic richness (mean A = 12.2 ± 1.2). The majority of samples (99%) had unique multi-locus genotypes, indicating high genetic diversity in the sample set. Complex infections were observed in 66% of samples (mean MOI = 2.13 ± 0.04), with 33% of infections showing high within-host diversity as described by the Fws metric. Low, but significant LD (standardised index of association, ISA = 0.08, P < 0.001) was observed that indicates recombination of distinct clones. Limited impact of temporal (FST range − 0.00005 to 0.0003) and spatial (FST = − 0.028 to 0.023) variation on genetic diversity existed during the sampling timeframe and study sites respectively. Conclusions Consistent with the Vhembe District’s classification as a ‘high’ transmission setting within South Africa, P. falciparum diversity in the area was moderate to high and complex. This study showed that genetic diversity within the parasite population reflects the continued residual transmission observed in the Vhembe District. This data can be used as a reference point for the assessment of the effectiveness of on-going interventions over time, the identification of imported cases and/or outbreaks, as well as monitoring for the potential spread of anti-malarial drug resistance.

scholarly journals Parasite genetic diversity reflects continued residual malaria transmission in Vhembe District, a hotspot in the Limpopo Province of South Africa

2021 ◽  
Author(s):  
Hazel B. Gwarinda ◽  
Sofonias K. Tessema ◽  
Jaishree Raman ◽  
Bryan Greenhouse ◽  
Lyn-Marie Birkholtz
Keyword(s):  
South Africa ◽  
Genetic Diversity ◽  
Malaria Transmission ◽  
Limpopo Province ◽  
Parasite Population ◽  
High Genetic Diversity ◽  
Management Interventions ◽  
Imported Cases ◽  
Study Sites ◽  
Vhembe District

Abstract Background: South Africa aims to eliminate malaria transmission by 2023. However, despite sustained vector control efforts and case management interventions, the Vhembe District remains a malaria transmission hotspot. To better understand Plasmodium falciparum transmission dynamics in the area, this study characterised the genetic diversity of parasites circulating within the Vhembe District.Methods: A total of 1153 falciparum-positive rapid diagnostic tests (RDTs) were randomly collected from seven clinics within the district, over three consecutive years (2016, 2017 and 2018) during the wet and dry malaria transmission seasons. Using 26 neutral microsatellite markers, differences in genetic diversity were described using a multiparameter scale of multiplicity of infection (MOI), inbreeding metric (Fws), number of unique alleles (A), expected heterozygosity (He), multilocus linkage disequilibrium (LD) and genetic differentiation, and were associated with temporal and geospatial variances. Results: A total of 747 (65%) samples were successfully genotyped. Moderate to high genetic diversity (mean He = 0.74 ± 0.03) was observed in the parasite population. This was ascribed to high allelic richness (mean A = 12.2 ± 1.2). The majority of samples (99%) had unique multi-locus genotypes, indicating high genetic diversity in the sample set. Complex infections were observed in 66% of samples (mean MOI = 2.13 ± 0.04), with 33% of infections showing high within-host diversity as described by the Fws metric. Low, but significant LD (standardised index of association, ISA = 0.08, P < 0.001) was observed that indicates recombination of distinct clones. Limited impact of temporal (FST range -0.00005 to 0.0003) and spatial (FST = –0.028 to 0.023) variation on genetic diversity existed during the sampling timeframe and study sites respectively. Conclusion: Consistent with the Vhembe District’s classification as a 'high' transmission setting within South Africa, P. falciparum diversity in the area was moderate to high and complex. This study showed that genetic diversity within the parasite population reflects the continued residual transmission observed in the Vhembe District. This data can be used as a reference point for the assessment of the effectiveness of on-going interventions over time, the identification of imported cases and/or outbreaks, as well as monitoring for the potential spread of antimalarial drug resistance.

scholarly journals Parasite Genetic Diversity Reflects Continued Residual Malaria Transmission in Vhembe District, A Hotspot in the Limpopo Province of South Africa

2020 ◽  
Author(s):  
Hazel B. Gwarinda ◽  
Sofonias K. Tessema ◽  
Jaishree Raman ◽  
Bryan Greenhouse ◽  
Lyn-Marié Birkholtz
Keyword(s):  
South Africa ◽  
Genetic Diversity ◽  
Malaria Transmission ◽  
Limpopo Province ◽  
Parasite Population ◽  
High Genetic Diversity ◽  
Host Diversity ◽  
Management Interventions ◽  
Study Sites ◽  
Vhembe District

Abstract Background: South Africa aims to eliminate malaria transmission by 2023. However, despite sustained vector control efforts and case management interventions, the Vhembe District in the Limpopo Province remains a malaria transmission hotspot. To better understand Plasmodium falciparum transmission dynamics in the area, this study characterised the genetic diversity of parasites circulating within the Vhembe District.Methods: A total of 1153 falciparum-positive rapid diagnostic tests (RDTs) were randomly collected from seven clinics within the district, over three consecutive years (2016, 2017 and 2018) during the wet and dry malaria transmission seasons. Parasite genomic material was isolated from the RDTs and parasite genetic diversity was characterised using 26 neutral microsatellite markers. Differences in genetic diversity were described using a multiparameter scale of multiplicity of infection (MOI), within-host diversity metric (Fws), number of unique alleles (A), expected heterozygosity (He), multilocus linkage disequilibrium (LD) and genetic differentiation (Wright's F-statistic, FST), and were associated with temporal and geospatial variances. Results: A total of 747 (65%) samples were successfully genotyped. High genetic diversity (mean heterozygosity, He = 0.74 ± 0.03) was observed in the parasite population. This was ascribed to high allelic richness (mean A = 12.2 ± 1.2). The majority of samples (99%) had unique multi-locus genotypes, indicating high genetic diversity in the sample set. Complex infections were observed in 66% of samples (mean MOI = 2.13 ± 0.04), with 33% of infections showing high within-host diversity as described by the Fws metric. Low, but significant LD (standardised index of association, ISA = 0.08, P < 0.001) was observed that indicates recombination of distinct clones. Limited impact of temporal (FST range -0.00005 to 0.0003) and spatial (FST = –0.028 to 0.023) variation on genetic diversity existed during the sampling timeframe and study sites respectively. Conclusion: Consistent with the Vhembe District’s classification as a 'high' transmission setting within South Africa, P. falciparum diversity in the area was high and complex. This study showed that genetic diversity within the parasite population reflects the continued residual transmission observed in the Vhembe District. This finding, together with continued surveillance of P. falciparum genetic diversity in South Africa, may influence future intervention strategies by targeting the parasite to decrease transmission intensity for the country to achieve its elimination goals.

scholarly journals Rainfall Trends and Extremes in Saudi Arabia in Recent Decades

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 964 ◽  
Author(s):  
Mansour Almazroui
Keyword(s):  
Saudi Arabia ◽  
Extreme Events ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Annual Rainfall ◽  
Economic Damage ◽  
Total Rainfall ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Rainfall Trends

The observed records of recent decades show increased economic damage associated with flash flooding in different regions of Saudi Arabia. An increase in extreme rainfall events may cause severe repercussions for the socio-economic sectors of the country. The present study investigated the observed rainfall trends and associated extremes over Saudi Arabia for the 42-year period of 1978–2019. It measured the contribution of extreme events to the total rainfall and calculated the changes to mean and extreme rainfall events over five different climate regions of Saudi Arabia. Rainfall indices were constructed by estimating the extreme characteristics associated with daily rainfall frequency and intensity. The analysis reveals that the annual rainfall is decreasing (5.89 mm decade−1, significant at the 90% level) over Saudi Arabia for the entire analysis period, while it increased in the most recent decade. On a monthly scale, the most significant increase (5.44 mm decade−1) is observed in November and the largest decrease (1.20 mm decade−1) in January. The frequency of intense rainfall events is increasing for the majority of stations over Saudi Arabia, while the frequency of weak events is decreasing. More extreme rainfall events are occurring in the northwest, east, and southwest regions of Saudi Arabia. A daily rainfall of ≥ 26 mm is identified as the threshold for an extreme event. It is found that the contribution of extreme events to the total rainfall amount varies from region to region and season to season. The most considerable contribution (up to 56%) is found in the southern region in June. Regionally, significant contribution comes from the coastal region, where extreme events contribute, on average, 47% of the total rainfall each month from October to February, with the largest (53%) in November. For the entire country, extreme rainfall contributes most (52%) in November and least (20%) in July, while contributions from different stations are in the 8–50% range of the total rainfall.

scholarly journals Parasite genetic diversity reflects continued residual malaria transmission in Vhembe District, a hotspot in the Limpopo Province of South Africa

2021 ◽  
Author(s):  
Hazel B. Gwarinda ◽  
Sofonias K. Tessema ◽  
Jaishree Raman ◽  
Bryan Greenhouse ◽  
Lyn-Marie Birkholtz
Keyword(s):  
South Africa ◽  
Genetic Diversity ◽  
Malaria Transmission ◽  
Limpopo Province ◽  
Parasite Population ◽  
High Genetic Diversity ◽  
Management Interventions ◽  
Imported Cases ◽  
Study Sites ◽  
Vhembe District

Abstract Background South Africa aims to eliminate malaria transmission by 2023. However, despite sustained vector control efforts and case management interventions, the Vhembe District remains a malaria transmission hotspot. To better understand Plasmodium falciparum transmission dynamics in the area, this study characterized the genetic diversity of parasites circulating within the Vhembe District.Methods A total of 1153 falciparum-positive rapid diagnostic tests (RDTs) were randomly collected from seven clinics within the district, over three consecutive years (2016, 2017 and 2018) during the wet and dry malaria transmission seasons. Using 26 neutral microsatellite markers, differences in genetic diversity were described using a multiparameter scale of multiplicity of infection (MOI), inbreeding metric (Fws), number of unique alleles (A), expected heterozygosity (He), multilocus linkage disequilibrium (LD) and genetic differentiation, and were associated with temporal and geospatial variances. Results A total of 747 (65%) samples were successfully genotyped. Moderate to high genetic diversity (mean He = 0.74 ± 0.03) was observed in the parasite population. This was ascribed to high allelic richness (mean A = 12.2 ± 1.2). The majority of samples (99%) had unique multi-locus genotypes, indicating high genetic diversity in the sample set. Complex infections were observed in 66% of samples (mean MOI = 2.13 ± 0.04), with 33% of infections showing high within-host diversity as described by the Fws metric. Low, but significant LD (standardised index of association, ISA = 0.08, P < 0.001) was observed that indicates recombination of distinct clones. Limited impact of temporal (FST range -0.00005 to 0.0003) and spatial (FST = –0.028 to 0.023) variation on genetic diversity existed during the sampling timeframe and study sites respectively. Conclusion Consistent with the Vhembe District’s classification as a 'high' transmission setting within South Africa, P. falciparum diversity in the area was moderate to high and complex. This study showed that genetic diversity within the parasite population reflects the continued residual transmission observed in the Vhembe District. This data can be used as a reference point for the assessment of the effectiveness of on-going interventions over time, the identification of imported cases and/or outbreaks, as well as monitoring for the potential spread of anti-malarial drug resistance.

scholarly journals Time Series Analysis of Trend and Variability of Monthly Total Rainfall

2021 ◽  
Vol 10 (2) ◽  
pp. 104-114
Author(s):  
R. Ramakrishna ◽  
◽  
R.Gautham Goud ◽  
Alemayehu Sbhat ◽  
◽  
...  
Keyword(s):  
Time Series ◽  
Arima Model ◽  
Monthly Rainfall ◽  
Descriptive Statistics ◽  
Total Rainfall ◽  
Tigray Region ◽  
Augmented Dickey Fuller ◽  
Monthly Total ◽  
Accumulated Rainfall ◽  
History Of

The long-term variation in rainfall, one of the most important conditions for the climate in a particular region. The purpose of this study was to analysis the total monthly rainfall in the Maychew, which is located in the Tigray region of Ethiopia. The monthly rainfall is on the Maychew meteorological station has been calculated for the period from 2007-2018. The data were analyzed with the help of Minitab-14, R-3.3.1 an Overview of the descriptive statistics and unvaried, Box-Jenkins method, The seasonal ARIMA model was built to analyze the observed data and forecast the total rainfall, after the detection of nonstationarity using the Augmented Dickey-Fuller Test is a Test, and time plot. Some of the main findings of the study indicated that the monthly total rainfall tends to increase. In addition, it was found that, on the basis of the data contained in the history of the last twelve years of age. In addition, the descriptive statistics show that the average amount of rainfall in the Maychew is 58.82. After non-seasonal the first-order differentiation and once seasonal series, differentiation, they will be moved. A time series model for the Maychew Station and was adapted to be processed, diagnostically tested, and ultimately, to be obtained by SARIMA (3, 2, 2)*(0, 2, 2)12 a model has been created, and this model was used to Forecast the two years monthly values of the total rainfall. The forecasted accumulated rainfall values showed a similar pattern to the previous reports.

scholarly journals An External Agribusiness Risk Analysis Using KBDI: A Case of Veldfires in the Northern Territory of Australia

2020 ◽  
Vol 3 (1) ◽  
pp. 37
Author(s):  
Toyi Maniki Diphagwe ◽  
Bernard Moeketsi Hlalele ◽  
Dibuseng Priscilla Mpakathi
Keyword(s):  
Time Series ◽  
Probability Distribution ◽  
Crop Production ◽  
Time Series Data ◽  
Northern Territory ◽  
Return Level ◽  
Series Data ◽  
Burned Area ◽  
Trend Test ◽  
P Value

The 2019/20 Australian bushfires burned over 46 million acres of land, killed 34 people and left 3500 individuals homeless. Majority of deaths and buildings destroyed were in New South Wales, while the Northern Territory accounted for approximately 1/3 of the burned area. Many of the buildings that were lost were farm buildings, adding to the challenge of agricultural recovery that is already complex because of ash-covered farmland accompanied by historic levels of drought. The current research therefore aimed at characterising veldfire risk in the study area using Keetch-Byram Drought Index (KBDI). A 39-year-long time series data was obtained from an online NASA database. Both homogeneity and stationarity tests were deployed using a non-parametric Pettitt’s and Dicky-Fuller tests respectively for data quality checks. Major results revealed a non-significant two-tailed Mann Kendall trend test with a p-value = 0.789 > 0.05 significance level. A suitable probability distribution was fitted to the annual KBDI time series where both Kolmogorov-Smirnov and Chi-square tests revealed Gamma (1) as a suitably fitted probability distribution. Return level computation from the Gamma (1) distribution using XLSTAT computer software resulted in a cumulative 40-year return period of moderate to high fire risk potential. With this low probability and 40-year-long return level, the study found the area less prone to fire risks detrimental to animal and crop production. More agribusiness investments can safely be executed in the Northern Territory without high risk aversion.

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