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Malar J. 2024 February 21; DOI:10.21203/rs.3.rs-3959166/v1
Fuente IMdl, Benito MJS, Gisbert FB, García L, González V, et al.
Malar J. 2024 February 21; DOI:10.21203/rs.3.rs-3959166/v1
BACKGROUND
Malaria genetic diversity is an important indicator of malaria transmission. Pfmsp1 and pfmsp2 are a frequent molecular epidemiology tool to assess the genetic diversity. This study aims to assess the genetic diversity and the description of multiplicity of infection (MOI) of P. falciparum in Yambio County, South Sudan. Additionally, it assesses the association of specific alleles or multiplicity of infection with antimalarial drugs resistance haplotypes and severity of infection, major challenges in malaria control strategies.
METHODS
There were collected 446 malaria samples from patients in Yambio county. After P. falciparum confirmation, pfmsp1 and pfmsp2 allelic families were genotyped. Frequencies of each alleles were described and multiplicity of infection was calculated. The association between MOI and complicated malaria was assessed using U-Mann Whitney test. The Kruskal-Wallis test was used to compare MOI between collection sites, age groups and antimalarial resistance haplotypes.
RESULTS
For pfmsp1, monomorphic K1 allele infection was predominant (37.0%) in every location and for pfmsp2 locus, monomorphic 3D7 was predominant (44.8%). 71.9% of samples were polyclonal infections (overall MOI = 1.96). The high diversity and polyclonal infections are associated with molecular markers of resistance, and high MOI has been related with a lower risk of severity of infections. There was not find evidence of association between a specific allele and an infection trait.
CONCLUSION
High genetic diversity and high level of polyclonal infections have been found in this study, confirming the general high transmission, and highlighting the need for control measures to be intensified in Yambio county, South Sudan.
Malaria genetic diversity is an important indicator of malaria transmission. Pfmsp1 and pfmsp2 are a frequent molecular epidemiology tool to assess the genetic diversity. This study aims to assess the genetic diversity and the description of multiplicity of infection (MOI) of P. falciparum in Yambio County, South Sudan. Additionally, it assesses the association of specific alleles or multiplicity of infection with antimalarial drugs resistance haplotypes and severity of infection, major challenges in malaria control strategies.
METHODS
There were collected 446 malaria samples from patients in Yambio county. After P. falciparum confirmation, pfmsp1 and pfmsp2 allelic families were genotyped. Frequencies of each alleles were described and multiplicity of infection was calculated. The association between MOI and complicated malaria was assessed using U-Mann Whitney test. The Kruskal-Wallis test was used to compare MOI between collection sites, age groups and antimalarial resistance haplotypes.
RESULTS
For pfmsp1, monomorphic K1 allele infection was predominant (37.0%) in every location and for pfmsp2 locus, monomorphic 3D7 was predominant (44.8%). 71.9% of samples were polyclonal infections (overall MOI = 1.96). The high diversity and polyclonal infections are associated with molecular markers of resistance, and high MOI has been related with a lower risk of severity of infections. There was not find evidence of association between a specific allele and an infection trait.
CONCLUSION
High genetic diversity and high level of polyclonal infections have been found in this study, confirming the general high transmission, and highlighting the need for control measures to be intensified in Yambio county, South Sudan.
Journal Article > ResearchFull Text
Am J Trop Med Hyg. 2023 September 25; Online ahead of print; tpmd230382.; DOI:10.4269/ajtmh.23-0382
Molina-de la Fuente I, Sagrado Benito MJ, Ousley J, Gisbert FdB, García L, et al.
Am J Trop Med Hyg. 2023 September 25; Online ahead of print; tpmd230382.; DOI:10.4269/ajtmh.23-0382
Artemisinin-combined treatments are the recommended first-line treatment of Plasmodium falciparum malaria, but they are being threatened by emerging artemisinin resistance. Mutations in pfk13 are the principal molecular marker for artemisinin resistance. This study characterizes the presence of mutations in pfk13 in P. falciparum in Western Equatoria State, South Sudan. We analyzed 468 samples from patients with symptomatic malaria and found 15 mutations (8 nonsynonymous and 7 synonymous). Each mutation appeared only once, and none were validated or candidate markers of artemisinin resistance. However, some mutations were in the same or following position of validated and candidate resistance markers, suggesting instability of the gene that could lead to resistance. The R561L nonsynonymous mutation was found in the same position as the R561H validated mutation. Moreover, the A578S mutation, which is widespread in Africa, was also reported in this study. We found a high diversity of other pfk13 mutations in low frequency. Therefore, routine molecular surveillance of resistance markers is highly recommended to promptly detect the emergence of resistance-related mutations and to limit their spread.
Journal Article > ResearchFull Text
Epidemiol Infect. 2013 July 18; Volume 142 (Issue 4); DOI:10.1017/S0950268813001696
Besa NC, Coldiron ME, Bakri A, Raji A, Nsuami MJ, et al.
Epidemiol Infect. 2013 July 18; Volume 142 (Issue 4); DOI:10.1017/S0950268813001696
SUMMARY A diphtheria outbreak occurred from February to November 2011 in the village of Kimba and its surrounding settlements, in Borno State, northeastern Nigeria. We conducted a retrospective outbreak investigation in Kimba village and the surrounding settlements to better describe the extent and clinical characteristics of this outbreak. Ninety-eight cases met the criteria of the case definition of diphtheria, 63 (64·3%) of whom were children aged <10 years; 98% of cases had never been immunized against diphtheria. None of the 98 cases received diphtheria antitoxin, penicillin, or erythromycin during their illness. The overall case-fatality ratio was 21·4%, and was highest in children aged 0-4 years (42·9%). Low rates of immunization, delayed clinical recognition of diphtheria and absence of treatment with antitoxin and appropriate antibiotics contributed to this epidemic and its severity.