Genetic diversity of Plasmodium falciparum infection among children with uncomplicated malaria living in Pointe-Noire, Republic of Congo

Introduction: molecular characterization of malaria parasites from different localities is important to improve understanding of acquisition of natural immunity to Plasmodium falciparum, to assist in identifying the most appropriate strategies for control and to evaluate the impact of control interventions. This study aimed to determine the genetic diversity and the multiplicity of infection in Plasmodium falciparum isolates from Pointe-Noire, Republic of Congo. Methods: Plasmodium falciparum isolates were collected from 71 children with uncomplicated malaria; enrolled into the study for evaluating the therapeutic efficacy of artemether-lumefantrine combination. Both msp-1 and msp-2 genes were genotyped. Results: from 296 distinct fragments detected, 13 msp-1 and 27 msp-2 different alleles were identified. For msp-1, RO33 family was poorly polymorphic. The K1 family has shown the trend of predominance (41%), followed by Mad20 (35%). Comparatively to msp-2, 49.6% and 48.8% fragments belonged to 3D7 and FC27 respectively. Taking together msp-1 and msp-2 genes, the overall multiplicity of infection has been increased to 2.64 and 86% harbored more than one parasite genotype. Parasite density was not influenced by age as well as the multiplicity of infection which was not influenced neither by age nor by parasite density. Conclusion: genetic diversity of Plasmodium falciparum in isolates from patients with uncomplicated malaria in Pointe-Noire is high and consisted mainly of multiple clones. The overall multiplicity of infection has been largely increased when considering msp-1 and msp-2 genes together. With the changes in malaria epidemiology, the use of both msp-1 and msp-2 genes in the characterization of Plasmodium falciparum infection is recommended

Genetic polymorphism of merozoite surface protein 2 and prevalence of K76T pfcrt mutation in Plasmodium falciparum field isolates from Congolese children with asymptomatic infections

<p>Abstract</p> <p>Background</p> <p>In order to prepare the field site for future interventions, the prevalence of asymptomatic <it>Plasmodium falciparum </it>infection was evaluated in a cohort of children living in Brazzaville. <it>Plasmodium falciparum </it>merozoite surface protein 2 gene (<it>msp</it>2) was used to characterize the genetic diversity and the multiplicity of infection. The prevalence of mutant <it>P. falciparum </it>chloroquine resistance transporter (<it>pfcrt</it>) allele in isolates was also determined.</p> <p>Methods</p> <p>Between April and June 2010, 313 children below 10 years of age enrolled in the cohort for malaria surveillance were screened for <it>P. falciparum </it>infection using microscopy and polymerase chain reaction (PCR). The children were selected on the basis of being asymptomatic. <it>Plasmodium falciparum msp2 </it>gene was genotyped by allele-specific nested PCR and the <it>pfcrt </it>K76T mutation was detected using nested PCR followed by restriction endonuclease digestion.</p> <p>Results</p> <p>The prevalence of asymptomatic <it>P. falciparum </it>infections was 8.6% and 16% by microscopy and by PCR respectively. Allele typing of the <it>msp2 </it>gene detected 55% and 45% of 3D7 and FC27 allelic families respectively. The overall multiplicity of infections (MOI) was 1.3. A positive correlation between parasite density and multiplicity of infection was found. The prevalence of the mutant <it>pfcrt </it>allele (T76) in the isolates was 92%.</p> <p>Conclusion</p> <p>This is the first molecular characterization of <it>P. falciparum </it>field isolates in Congolese children, four years after changing the malaria treatment policy from chloroquine (CQ) to artemisinin-based combination therapy (ACT). The low prevalence of asymptomatic infections and MOI is discussed in the light of similar studies conducted in Central Africa.</p

Molecular monitoring of plasmodium falciparum drug susceptibility at the time of the introduction of artemisinin-based combination therapy in Yaoundé, Cameroon: Implications for the future

<p>Abstract</p> <p>Background</p> <p>Regular monitoring of the levels of anti-malarial resistance of <it>Plasmodium falciparum </it>is an essential policy to adapt therapy and improve malaria control. This monitoring can be facilitated by using molecular tools, which are easier to implement than the classical determination of the resistance phenotype. In Cameroon, chloroquine (CQ), previously the first-line therapy for uncomplicated malaria was officially withdrawn in 2002 and replaced initially by amodiaquine (AQ) monotherapy. Then, artemisinin-based combination therapy (ACT), notably artesunate-amodiaquine (AS-AQ) or artemether-lumefantrine (AL), was gradually introduced in 2004. This situation raised the question of the evolution of <it>P. falciparum </it>resistance molecular markers in Yaoundé, a highly urbanized Cameroonian city.</p> <p>Methods</p> <p>The genotype of <it>pfcrt </it>72 and 76 and <it>pfmdr1 </it>86 alleles and <it>pfmdr1 </it>copy number were determined using real-time PCR in 447 <it>P. falciparum </it>samples collected between 2005 and 2009.</p> <p>Results</p> <p>This study showed a high prevalence of parasites with mutant <it>pfcrt </it>76 (83%) and <it>pfmdr1 </it>86 (93%) codons. On the contrary, no mutations in the <it>pfcrt </it>72 codon and no samples with duplication of the <it>pfmdr1 </it>gene were observed.</p> <p>Conclusion</p> <p>The high prevalence of mutant <it>pfcrt </it>76T and <it>pfmdr1 </it>86Y alleles might be due to the choice of alternative drugs (AQ and AS-AQ) known to select such genotypes. Mutant <it>pfcrt </it>72 codon was not detected despite the prolonged use of AQ either as monotherapy or combined with artesunate. The absence of <it>pfmdr1 </it>multicopies suggests that AL would still remain efficient. The limited use of mefloquine or the predominance of mutant <it>pfmdr1 </it>86Y codon could explain the lack of <it>pfmdr1 </it>amplification. Indeed, this mutant codon is rarely associated with duplication of <it>pfmdr1 </it>gene. In Cameroon, the changes of therapeutic strategies and the simultaneous use of several formulations of ACT or other anti-malarials that are not officially recommended result in a complex selective pressure, rendering the prediction of the evolution of <it>P. falciparum </it>resistance difficult. This public health problem should lead to increased vigilance and regular monitoring.</p

Strategies for monitoring zoonotic diseases in the Republic of the Congo

International audienceEmerging viruses, both zoonotic and vector-borne, pose a significant threat to global health due to a complex confluence of events involving the role of pathogen reservoirs and exposure risks, including their facili- tating and intrinsic host factors. The implementation of strategies allowing early detection, and thus anticipation of these events, represents one of the major keys to the control of these diseases. We describe here the strategy implemented in the early detection of zoonotic events in the Republic of the Congo. One of the weaknesses identified in the country’s zoonotic surveillance is the lack of an information relay system between the central level and the populations living at the wildlife interface. In addition, there is a lack of training of community and/or health workers in taking appropriate samples and transporting them, as well as an absence of appropriate diagnostic means. The main focus was the implementation of wildlife mortality surveillance combined with seroprevalence surveys and public education on the human-animal interface. The aim was to set up a network for reporting wildlife mortality in an area covering 1/6th of the national territory, coupled with specific immunoglobulin G (IgG) detection in at-risk populations and educational actions aimed at promoting behavioral change among people living at the human-animal interface. In addition, training of indigenous populations in reporting animal carcasses, collecting specimens and transferring them to laboratories were conducted. As a result, more than 6,600 people were trained and collected 58 carcasses. The second component was the establishment of a rapid response team of 30 people trained in field epidemiology, and the final part included the strengthening of diagnostic capacities in the country. The establishment of this strategy can serve as a model for early warning and highlights the importance of involving local populations, veterinary services through ecoguards, and human health services in the same health surveillance dynamic. Future seroprevalence surveys will add valuable information on spatial distribution and risk factors of contamination

Viral and Bacterial Etiology of Common Respiratory Infections in Sub-Saharan Africa: A Review

Background: Respiratory infections are a major public health problem worldwide, with potentially serious consequences. Indeed, these infections remain one of the main causes of morbidity and mortality in children under 5 years old in developing countries. Etiological information on respiratory infections is crucial for prevention and case management strategies. This systematic review aims to describe the etiology of respiratory infections reported in studies carried out in sub-Saharan African countries; (2) Methods: Using PubMed, HINARI and Google scholar search engines, a systematic search was carried out to identify published articles on the etiology of viral and/or bacterial respiratory infections in sub-Saharan Africa in patients of all ages. We have only considered data from sub-Saharan Africa. Papers published from 2010 to 2021, in English or French have been included in this review; (3) Results: After reviewing 115 articles reporting studies carried out in the African continent, only 32 articles were selected of which, studies were conducted in 15 sub-Saharan African countries, including 6/32 (18.75%) in Cameroon. Twenty (62.5%) were cross-sectional studies, and twenty-four (75%) were hospital-based investigations. In these studies, RT-PCR and culture methods were respectively used for viruses and bacteria investigations. Respiratory syncytial virus was the most frequently identified, with prevalence ranging from 0.6% to 59%, followed by rhinovirus (9.3% -73%), influenza virus (flu) A/B (0.9%-69.1%), and human adenovirus (0.9% - 30.8%). Streptococcus pneumoniae (14.2% - 96%), followed by Haemophilus influenzae type b (2.5% - 54%), and Klebsiella pneumoniae (1.4% - 49.9%) were the most frequently detected bacteria; (4) Conclusions: This review has reported that many pathogens, mainly viruses, are associated with acute respiratory infections in sub-Saharan Africa in both children and adults. Unfortunately, the limited geographical distribution of data across sub-Saharan Africa does not allow most of countries to develop an effective strategy for the prevention and treatment of respiratory infections