Bernard Marcel Diop

A Reliable Diagnosis of Human Rabies Based on Analysis of Skin Biopsy Specimens

BACKGROUND The number of human deaths due to rabies is currently underestimated to be 55,000 deaths per year. Biological diagnostic methods for confirmation of rabies remain limited, because testing on postmortem cerebral samples is the reference method, and in many countries, sampling brain tissue is rarely practiced. There is a need for a reliable method based on a simple collection of nonneural specimens. METHODS A new reverse-transcription, heminested polymerase chain reaction (RT-hnPCR) protocol was standardized at 3 participating centers in Cambodia, Madagascar, and France. Fifty-one patients from Cambodia, Madagascar, Senegal, and France were prospectively enrolled in the study; 43 (84%) were ultimately confirmed as having rabies. A total of 425 samples were collected from these patients during hospitalization. We studied the accuracy of the diagnosis by comparing the results obtained with use of biological fluid specimens (saliva and urine) and skin biopsy specimens with the results obtained with use of the standard rabies diagnostic procedure performed with a postmortem brain biopsy specimen. RESULTS The data obtained indicate a high specificity (100%) of RT-hnPCR and a higher sensitivity (>/=98%) when the RT-hnPCR was performed with skin biopsy specimens than when the test was performed with fluid specimens, irrespective of the time of collection (i.e., 1 day after the onset of symptoms or just after death). Also, a sensitivity of 100% was obtained with the saliva sample when we analyzed at least 3 successive samples per patient. CONCLUSIONS Skin biopsy specimens should be systematically collected in cases of encephalitis of unknown origin. These samples should be tested by RT-hnPCR immediately to confirm rabies; if the technique is not readily available locally, the samples should be tested retrospectively for epidemiological purposes.

Enhanced Basophil Reactivities during Severe Malaria and Their Relationship with the Plasmodium falciparum Histamine-Releasing Factor Translationally Controlled Tumor Protein

ABSTRACT Recent studies suggest shared pathogenic pathways during malaria and allergy. Indeed, IgE, histamine, and the parasite-derived Plasmodium falciparum histamine-releasing factor translationally controlled tumor protein (PfTCTP) can be found at high levels in serum from patients experiencing malaria, but their relationship with basophil activation remains unknown. We recruited P. falciparum-infected patients in Senegal with mild malaria (MM; n = 19) or severe malaria (SM; n = 9) symptoms and healthy controls (HC; n = 38). Levels of serum IgE, PfTCTP, and IgG antibodies against PfTCTP were determined by enzyme-linked immunosorbent assays (ELISA). Basophil reactivities to IgE-dependent and -independent stimulations were measured ex vivo using fresh blood by looking at the expression level of the basophil activation marker CD203c with flow cytometry. Unstimulated basophils from MM had significantly lower levels of CD203c expression compared to those from HC and SM. After normalization on this baseline level, basophils from SM showed an enhanced reactivity to calcimycin (A23187) and hemozoin. Although SM reached higher median levels of activation after anti-IgE stimulation, great interindividual differences did not allow the results to reach statistical significance. When primed with recombinant TCTP before anti-IgE, qualitative differences in terms of a better ability to control excessive activation could be described for SM. IgE levels were very high in malaria patients, but concentrations in MM and SM were similar and were not associated with basophil responses, which demonstrates that the presence of IgE alone cannot explain the various basophil reactivities. Indeed, PfTCTP could be detected in 32% of patients, with higher concentrations for SM. These PfTCTP-positive patients displayed significantly higher basophil reactivities to any stimulus. Moreover, the absence of anti-PfTCTP IgG was associated with higher responses in SM but not MM. Our results show an association between basophil reactivity and malaria severity and suggest a pathogenic role for plasmodial PfTCTP in the induction of this allergy-like mechanism.

Parasite polymorphism and severe malaria in Dakar (Senegal): a West African urban area.

Background Transmission of malaria in West African urban areas is low and healthcare facilities are well organized. However, malaria mortality remains high. We conducted a survey in Dakar with the general objective to establish who died from severe malaria (SM) in urban areas (particularly looking at the age-groups) and to compare parasite isolates associated with mild or severe malaria. Methodology/Principal Findings The current study included mild- (MM) and severe malaria (SM) cases, treated in dispensaries (n = 2977) and hospitals (n = 104), We analysed Pfdhfr/Pfcrt-exon2 and nine microsatellite loci in 102 matched cases of SM and MM. Half of the malaria cases recorded at the dispensaries and 87% of SM cases referred to hospitals, occurred in adults, although adults only accounted for 26% of all dispensary consultations. This suggests that, in urban settings, whatever the reason for this adult over-representation, health-workers are forced to take care of increasing numbers of malaria cases among adults. Inappropriate self treatment and mutations in genes associated with drug resistance were found associated with SM in adults. SM was also associated with a specific pool of isolates highly polymorphic and different from those associated with MM. Conclusion In this urban setting, adults currently represent one of the major groups of patients attending dispensaries for malaria treatment. For these patients, despite the low level of transmission, SM was associated with a specific and highly polymorphic pool of parasites which may have been selected by inappropriate treatment.

Profil actuel de la toxoplasmose cérébrale en milieu hospitalier à Dakar

OBJECTIVE To describe the current epidemiologic, clinical, diagnostic, and prognostic characteristics of cerebral toxoplasmosis in a hospital setting in Dakar. METHODS This descriptive and analytic study examined the records of all HIV-positive patients with cerebral toxoplasmosis hospitalized at the infectious disease department at Fann (teaching) Hospital from January 2007 through December 2010. The diagnosis was based on clinical and computed tomography criteria completed by a therapeutic test with Cotrimoxazole. RESULTS There were 26 cases of cerebral toxoplasmosis during the study period. The sex ratio (F/M) was 1.4. The mean age was 41.5 ± 11.2 years. The clinical signs were predominantly fever (88.5%), headache (77.5%), focal signs (64.5%), and disorders of consciousness (61.5%). Brain lesions were most often multiple (64.3%), with mass effects (54.1%) and peripheral edema (77.8%). Seven of the 26 patients died (lethality rate: 29.1%). Impaired consciousness (p = 0.023), high CD8 T-cell counts (p = 0.009), and anemia (p = 0.003) were significantly associated with a higher mortality rate. CONCLUSION Cerebral toxoplasmosis remains a complication of AIDS in Dakar. Anemia, impaired consciousness, and high CD8(+) T cell counts were factors indicative of poor prognosis.