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Molecular epidemiology of Plasmodium vivax and Plasmodium falciparum malaria among Duffy-positive and Duffy-negative populations in Ethiopia.

Lo E, Yewhalaw D, Zhong D, Zemene E, Degefa T, Tushune K, Ha M, Lee MC, James AA, Yan G - Malar. J. (2015)

Bottom Line: Parasite gene copy number was measured by quantitative real-time PCR and compared between symptomatic and asymptomatic samples, as well as between children/adolescents and adults from the local community.The prevalence of P. vivax and P. falciparum malaria is the highest in children compared to adolescents and adults.Samples from asymptomatic individuals show a significantly lower parasite gene copy number than those from symptomatic infections for P. vivax and P. falciparum.

View Article: PubMed Central - PubMed

Affiliation: Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92697, USA. eugenia.loyy@gmail.com.

ABSTRACT

Background: Malaria is the most prevalent communicable disease in Ethiopia, with 75% of the country's landmass classified as endemic for malaria. Accurate information on the distribution and clinical prevalence of Plasmodium vivax and Plasmodium falciparum malaria in endemic areas, as well as in Duffy-negative populations, is essential to develop integrated control strategies.

Methods: A total of 390 and 416 community and clinical samples, respectively, representing different localities and age groups across Ethiopia were examined. Malaria prevalence was estimated using nested PCR of the 18S rRNA region. Parasite gene copy number was measured by quantitative real-time PCR and compared between symptomatic and asymptomatic samples, as well as between children/adolescents and adults from the local community. An approximately 500-bp segment of the human DARC gene was amplified and sequenced to identify Duffy genotype at the -33rd nucleotide position for all the clinical and community samples.

Results: Plasmodium vivax prevalence was higher in the south while P. falciparum was higher in the north. The prevalence of P. vivax and P. falciparum malaria is the highest in children compared to adolescents and adults. Four P. vivax infections were detected among the Duffy-negative samples. Samples from asymptomatic individuals show a significantly lower parasite gene copy number than those from symptomatic infections for P. vivax and P. falciparum.

Conclusions: Geographical and age differences influence the distribution of P. vivax and P. falciparum malaria in Ethiopia. These findings offer evidence-based guidelines in targeting malaria control efforts in the country.

No MeSH data available.


Related in: MedlinePlus

Box plots of the log-transformed parasite gene copy number of the community and clinical samples. (A) Box plot of the log-transformed parasite gene copy number of Plasmodium vivax and Plasmodium falciparum measured by qPCR in children/adolescents of age under 18 and adults of age 18 and above. These samples represent the local community of Asendabo, Ethiopia. (B) Box plot showing the log-transformed parasite gene copy number of clinical Plasmodium vivax and Plasmodium falciparum cases in children/adolescents and adults from the six health centre/hospital sites in Ethiopia. The central box represents the interquartile range and the vertical lines represent the first and fourth quartiles of the data. The median is shown as a line through the centre of the box. Outlier samples are represented by open circles. P-values (above) are provided for the comparison of gene copy number between the two age groups with respect to P. vivax and P. falciparum. Numbers (bottom) indicate the number of individuals included.
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Fig2: Box plots of the log-transformed parasite gene copy number of the community and clinical samples. (A) Box plot of the log-transformed parasite gene copy number of Plasmodium vivax and Plasmodium falciparum measured by qPCR in children/adolescents of age under 18 and adults of age 18 and above. These samples represent the local community of Asendabo, Ethiopia. (B) Box plot showing the log-transformed parasite gene copy number of clinical Plasmodium vivax and Plasmodium falciparum cases in children/adolescents and adults from the six health centre/hospital sites in Ethiopia. The central box represents the interquartile range and the vertical lines represent the first and fourth quartiles of the data. The median is shown as a line through the centre of the box. Outlier samples are represented by open circles. P-values (above) are provided for the comparison of gene copy number between the two age groups with respect to P. vivax and P. falciparum. Numbers (bottom) indicate the number of individuals included.

Mentions: The overall parasite prevalence in children aged from 0–5 (31.9%) was the highest among the three age groups in the community samples (adolescents: 14.1%; adults: 15.8%; Table 2). The prevalence of P. vivax infections in children (13.9%) was > two-times higher than in adolescents (6.3%) and > five-times higher than in adults (2.6%; Table 2). Among the P. falciparum infected samples, prevalence was the highest in children (18.1%) followed by adults (14.2%) and adolescents (7%; Table 2). Despite the small sample size of P. vivax infection detected in the community samples (Table 2), the P. vivax gene copy number in children (mean GCN and standard deviation: 1.51 ± 1.23/μl) and adolescents (1.08 ± 0.24/μl) were significantly higher than that in adults (0.49 ± 0.80/μl) (P < 0.05; Figure 2A). For P. falciparum, no significant difference was found in the parasite GCN among the three age groups (Figure 2A). Among the infected community samples, only one individual (from the adolescent aged 6–18) was found to contain both P. vivax and P. falciparum (Table 2). The proportions of P. falciparum infection were slightly higher than P. vivax in both the children and adolescents; and this difference was substantial in adults where the majority of the infections are P. falciparum.Figure 2


Molecular epidemiology of Plasmodium vivax and Plasmodium falciparum malaria among Duffy-positive and Duffy-negative populations in Ethiopia.

Lo E, Yewhalaw D, Zhong D, Zemene E, Degefa T, Tushune K, Ha M, Lee MC, James AA, Yan G - Malar. J. (2015)

Box plots of the log-transformed parasite gene copy number of the community and clinical samples. (A) Box plot of the log-transformed parasite gene copy number of Plasmodium vivax and Plasmodium falciparum measured by qPCR in children/adolescents of age under 18 and adults of age 18 and above. These samples represent the local community of Asendabo, Ethiopia. (B) Box plot showing the log-transformed parasite gene copy number of clinical Plasmodium vivax and Plasmodium falciparum cases in children/adolescents and adults from the six health centre/hospital sites in Ethiopia. The central box represents the interquartile range and the vertical lines represent the first and fourth quartiles of the data. The median is shown as a line through the centre of the box. Outlier samples are represented by open circles. P-values (above) are provided for the comparison of gene copy number between the two age groups with respect to P. vivax and P. falciparum. Numbers (bottom) indicate the number of individuals included.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4340780&req=5

Fig2: Box plots of the log-transformed parasite gene copy number of the community and clinical samples. (A) Box plot of the log-transformed parasite gene copy number of Plasmodium vivax and Plasmodium falciparum measured by qPCR in children/adolescents of age under 18 and adults of age 18 and above. These samples represent the local community of Asendabo, Ethiopia. (B) Box plot showing the log-transformed parasite gene copy number of clinical Plasmodium vivax and Plasmodium falciparum cases in children/adolescents and adults from the six health centre/hospital sites in Ethiopia. The central box represents the interquartile range and the vertical lines represent the first and fourth quartiles of the data. The median is shown as a line through the centre of the box. Outlier samples are represented by open circles. P-values (above) are provided for the comparison of gene copy number between the two age groups with respect to P. vivax and P. falciparum. Numbers (bottom) indicate the number of individuals included.
Mentions: The overall parasite prevalence in children aged from 0–5 (31.9%) was the highest among the three age groups in the community samples (adolescents: 14.1%; adults: 15.8%; Table 2). The prevalence of P. vivax infections in children (13.9%) was > two-times higher than in adolescents (6.3%) and > five-times higher than in adults (2.6%; Table 2). Among the P. falciparum infected samples, prevalence was the highest in children (18.1%) followed by adults (14.2%) and adolescents (7%; Table 2). Despite the small sample size of P. vivax infection detected in the community samples (Table 2), the P. vivax gene copy number in children (mean GCN and standard deviation: 1.51 ± 1.23/μl) and adolescents (1.08 ± 0.24/μl) were significantly higher than that in adults (0.49 ± 0.80/μl) (P < 0.05; Figure 2A). For P. falciparum, no significant difference was found in the parasite GCN among the three age groups (Figure 2A). Among the infected community samples, only one individual (from the adolescent aged 6–18) was found to contain both P. vivax and P. falciparum (Table 2). The proportions of P. falciparum infection were slightly higher than P. vivax in both the children and adolescents; and this difference was substantial in adults where the majority of the infections are P. falciparum.Figure 2

Bottom Line: Parasite gene copy number was measured by quantitative real-time PCR and compared between symptomatic and asymptomatic samples, as well as between children/adolescents and adults from the local community.The prevalence of P. vivax and P. falciparum malaria is the highest in children compared to adolescents and adults.Samples from asymptomatic individuals show a significantly lower parasite gene copy number than those from symptomatic infections for P. vivax and P. falciparum.

View Article: PubMed Central - PubMed

Affiliation: Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA, 92697, USA. eugenia.loyy@gmail.com.

ABSTRACT

Background: Malaria is the most prevalent communicable disease in Ethiopia, with 75% of the country's landmass classified as endemic for malaria. Accurate information on the distribution and clinical prevalence of Plasmodium vivax and Plasmodium falciparum malaria in endemic areas, as well as in Duffy-negative populations, is essential to develop integrated control strategies.

Methods: A total of 390 and 416 community and clinical samples, respectively, representing different localities and age groups across Ethiopia were examined. Malaria prevalence was estimated using nested PCR of the 18S rRNA region. Parasite gene copy number was measured by quantitative real-time PCR and compared between symptomatic and asymptomatic samples, as well as between children/adolescents and adults from the local community. An approximately 500-bp segment of the human DARC gene was amplified and sequenced to identify Duffy genotype at the -33rd nucleotide position for all the clinical and community samples.

Results: Plasmodium vivax prevalence was higher in the south while P. falciparum was higher in the north. The prevalence of P. vivax and P. falciparum malaria is the highest in children compared to adolescents and adults. Four P. vivax infections were detected among the Duffy-negative samples. Samples from asymptomatic individuals show a significantly lower parasite gene copy number than those from symptomatic infections for P. vivax and P. falciparum.

Conclusions: Geographical and age differences influence the distribution of P. vivax and P. falciparum malaria in Ethiopia. These findings offer evidence-based guidelines in targeting malaria control efforts in the country.

No MeSH data available.


Related in: MedlinePlus