Thérèse Dieng

Prevalence of Plasmodium falciparum pfcrt polymorphisms and in vitro chloroquine sensitivity in Senegal

Mutations in pfcrt K76T are associated with chloroquine resistance in Plasmodium falciparum. Previous studies of K76T mutations in Senegal reported the association of T76 with in vitro-resistant isolates, but this mutation was also prevalent in chloroquine-sensitive isolates. This suggests involvement of additional genetic loci in modulating chloroquine resistance. Additional pfcrt polymorphisms at codons A220S, Q271E, N326S and R371I have been found in chloroquine-resistant isolates. We wanted to test if sequential acquisition of mutations at these codons leads to in vitro chloroquine resistance. Stepwise accumulation of mutations was not detected, rather there was almost complete linkage between the pfcrt K76T mutation and polymorphisms in these codons. Therefore these additional polymorphisms do not enhance the correlation between pfcrt T76 and chloroquine resistance in Senegal. These data suggest that in vitro chloroquine resistance requires the genetic background of the pfcrt K76T mutation and additional mutations in genetic loci outside the pfcrt gene.

Acute kidney injury associated with Plasmodium malariae infection

According to current estimates, Plasmodium malariae is not very common in Senegal, as more than 98% of malaria cases are suspected to be due to Plasmodium falciparum. However, it is possible that other malarial species are being under-reported or misdiagnosed. This is a report of a case of P. malariae in a 30-year-old man previously hospitalized with acute kidney injury after treatment with quinine and re-hospitalized three months later. He was diagnosed with renal cortical necrosis post malaria treatment. Plasmodium malariae was identified with light microscope and confirmed using species-specific small-subunit rRNA (ssrRNA) amplification.The patient was treated for malaria with intravenous quinine for seven days, followed by three days of oral treatment; the bacterial infection was treated using ceftriaxone during the first hospitalization and ciprofloxacin associated with ceftriaxone the second time. He also had four rounds of dialysis after which he partially recovered the renal function. Given the complications that can be caused by P. malariae infection, it should be systematically looked for, even if the predominant species is P. falciparum in Senegal.

Performance of Real-Time Polymerase Chain Reaction Assays for the Detection of 20 Gastrointestinal Parasites in Clinical Samples from Senegal

Gastrointestinal parasite infections represent one of the biggest public health problems in the world. Therefore, appropriate innovative tools are needed for assessing interventions to control these infections. This study aims to compare the performance of real-time polymerase chain reaction (PCR) assays to microscopic examination for detection of intestinal parasites. A direct microscopic examination and stool concentration was performed on 98 stool samples from patients attending Senegalese hospitals. Negative microscopic control samples were also collected in Nice and Marseille (France). Species-specific primers/probes were used to detect 20 common gastrointestinal protozoans and helminths. Positive frequency and the sensitivity of each real-time PCR assay were compared with conventional microscopic examination. Real-time PCR was positive in 72 of 98 samples (73.5%), whereas microscopic examination was positive in 37 (37.7%) samples (P < 0.001). The real-time PCR assays were more sensitive than microscopy, with 57.4% (31/54) versus 18.5% (10/54), respectively, in the detection of parasites in asymptomatic patients (P < 0.05). In terms of polyparasitism, there were more coinfections detected by real-time PCR assays compared with microscopic methods (25.5% versus 3.06%). In comparison to parasite prevalence on individual samples, the results showed a perfect agreement (100%) between the two techniques for seven species, whereas discrepancies were observed for the others (agreement percentage varying from 64.2% to 98.9%). Real-time PCR appeared to be superior to microscopic examination for the detection of parasites in stool samples. This assay will be useful in diagnostic laboratories and in the field for evaluating the efficacy of mass drug administration programs.

Recherche des spores de microsporidies chez des patients sidéens au CHU de Fann à Dakar (Sénégal): résultats préliminaires

Summary Microsporidia are protozoan parasites which can cause chronicdiarrhea in immunocompromised patients. Two species were found in the intestines of male patient: Enterocytozoon bieneusi and Encephalitozoon intestinalis . A prospective study was made on 31 AIDS patients suffering from diarrhea: stool samples were screened for microsporidian spores. 19 of these patients were HIV1 positive, 6 were HIV2 positive, and 7 were both HIV1 and HIV2 positive. Among the 19 HIV1 positive cases, 2 patients had low CD4 counts and 1 of these 2 patients was also infected by cryptosporidiosis.

Amplification of blood smear DNA to confirm disseminated histoplasmosis

BackgroundThe prevalence of the Histoplasma capsulatum var. capsulatum (Hcc) histoplasmosis may be underestimated West Africa, both because the diagnosis is not mentioned in the early stages of the disease and due to limited biological resources available.Case ReportWe report a case of disseminated histoplasmosis due to Hcc in a Senegalese HIV patient. The diagnosis was suspected following the demonstration of small encapsulated yeasts within neutrophils on a thin blood smear. It was further confirmed using a specific real-time PCR applied on a DNA specimen extracted from the thin blood smear.Conclusion To the best of our knowledge, this is the first case of Hcc infection diagnosed in Senegal. Blood smear may be a valuable screening tool in the case of bloodstream dissemination and can be used for further molecular approaches to confirm the diagnosis.

Epidemiological Profile of Intestinal Parasitic Infection among Preschool and School Children Living in a Rural Community in Senegal: A Cross Sectional Survey

Introduction: Intestinal parasitic infection (IPI) remains major public health problem in worldwide, being most prevalent in developing countries. Mass drug administration with Mebendazole is an effective strategy for the control of these diseases in pre-school and schoolchildren. The aim of this study was to assess the prevalence of intestinal parasitic infections and established associated risk factors among pre-school and schoolchildren living in rural area in Senegal. Materials and method: A cross sectional survey was carried out between Novembers to December 2014. Children less than 10 years were randomly selected using a systematic random sampling method. Stool samples were examined by light microscopy for the detection of parasite using direct examination, Modified Ritchie Method and the modified Ziehl Neelsen staining method. Results: Among 392 children selected in the study, 137 were found with at least one intestinal parasite representing an overall prevalence of 34.95% [CI 95% (29.3–41.3)]. Protozoan infection was more frequent than helminthic infection (93.4% versus 2.2% respectively). Association between helminths and protozoa was 4.4%. Intestinal parasites identified were Giardia intestinales (72.48%), Entamoeba coli (13.76%), Blastocystis hominis (3.67%) and Hymenolepis nana (1.83%). Prevalence was higher among children aged over 5 years old (48.4%) (aOR= 5.39; 95% IC (2.06–13.9); p=0.001). Children living in family with more than 10 individuals and those drinking unsafe water were found most infected respectively 37.5%) (aOR= 1.24; 95% CI (0.65–2.38); p=0.51) and (42.3%) (aOR=1.45; 95% CI (0.83–2.52); p=0.18). Prevalence was higher in children with underweight 36.3% [aOR= 1.53; 95% IC (0.88–2.67); p=0.13). No correlation was found between sex and intestinal parasitic infection. Conclusion: This study showed that intestinal parasites remain prevalent in pre-school and schoolchildren with a changing of the epidemiological profile. Protozoan infection was more frequent than helminthic infection. Preventive measures including mass drug administration with Albendazole and water supply could reduce the prevalence of these diseases.