Differences in pathogenicity and virulence of Trypanosoma brucei gambiense field isolates in experimentally infected Balb/C mice.

Trypanosoma brucei gambiense (T. b. gambiense) is the major causative agent of human African trypanosomiasis (HAT). A great variety of clinical outcomes have been observed in West African foci, probably due to complex host-parasite interactions. In order to separate the roles of parasite genetic diversity and host variability, we have chosen to precisely characterize the pathogenicity and virulence of T. b. gambiense field isolates in a mouse model. Thirteen T. b. gambiense strains were studied in experimental infections, with 20 Balb/C infected mice per isolate. Mice were monitored for 30 days, in which mortality, parasitemia, anemia, and weight were recorded. Mortality rate, prepatent period, and maximum parasitemia were estimated, and a survival analysis was performed to compare strain pathogenicity. Mixed models were used to assess parasitemia dynamics, weight, and changes in Packed Cell Volume (PCV). Finally, a multivariate analysis was performed to infer relationships between all variables. A large phenotypic diversity was observed. Pathogenicity was highly variable, ranging from strains that kill their host within 9 days to a non-pathogenic strain (no deaths during the experiment). Virulence was also variable, with maximum parasitemia values ranging from 42 million to 1 billion trypanosomes/ml. Reduced PCV and weight occurred in the first two weeks of the infection, with the exception of two strains. Finally, the global analysis highlighted three groups of strains: a first group with highly pathogenic strains showing an early mortality associated with a short prepatent period; a second group of highly virulent strains with intermediate pathogenicity; and a third group of isolates characterized by low pathogenicity and virulence patterns. Such biological differences could be related to the observed clinical diversity in HAT. A better understanding of the biological pathways underlying the observed phenotypic diversity could thus help to clarify the complex nature of the host-parasite interactions that determine the resistance/susceptibility status to T. brucei gambiense.

Accuracy of individual rapid tests for serodiagnosis of gambiense sleeping sickness in West Africa.

BACKGROUND: Individual rapid tests for serodiagnosis (RDT) of human African trypanosomiasis (HAT) are particularly suited for passive screening and surveillance. However, so far, no large scale evaluation of RDTs has been performed for diagnosis of Trypanosoma brucei gambiense HAT in West Africa. The objective of this study was to assess the diagnostic accuracy of 2 commercial HAT-RDTs on stored plasma samples from West Africa. METHODOLOGY/PRINCIPAL FINDINGS: SD Bioline HAT and HAT Sero-K-Set were performed on 722 plasma samples originating from Guinea and Côte d'Ivoire, including 231 parasitologically confirmed HAT patients, 257 healthy controls, and 234 unconfirmed individuals whose blood tested antibody positive in the card agglutination test but negative by parasitological tests. Immune trypanolysis was performed as a reference test for trypanosome specific antibody presence. Sensitivities in HAT patients were respectively 99.6% for SD Bioline HAT, and 99.1% for HAT Sero-K-Set, specificities in healthy controls were respectively 87.9% and 88.3%. Considering combined positivity in both RDTs, increased the specificity significantly (p ≤ 0.0003) to 93.4%, while 98.7% sensitivity was maintained. Specificities in controls were 98.7-99.6% for the combination of one or two RDTs with trypanolysis, maintaining a sensitivity of at least 98.1%. CONCLUSIONS/SIGNIFICANCE: The observed specificity of the single RDTs was relatively low. Serial application of SD Bioline HAT and HAT Sero-K-Set might offer superior specificity compared to a single RDT, maintaining high sensitivity. The combination of one or two RDTs with trypanolysis seems promising for HAT surveillance.

[Knowledge and practices of health care workers in the area of healthcare-associated infection risks. A case study in a district hospital in Burkina Faso]. / Connaissances et pratiques des professionnels de santé sur le risque infectieux associé aux soins : étude dans un hôpital de district au Burkina Faso.

INTRODUCTION: Healthcare-associated infections are a common consequence of unsafe health care practices and are a major issue for patient safety. Health care workers play a key role in patient safety and the quality of care, with factors such as poor compliance with hygiene standards and poor knowledge of infection risks having a major impact. However, the role of health care workers in patient safety has been overlooked in the literature. The objectives of this study were i) to examine health care workers' awareness of infection risks and ii) to assess levels of hand hygiene compliance and barriers to patient safety. METHODS: A one-day cross-sectional survey was conducted in June 2011 at the Ziniaré health district hospital. The study focused on the health care workers present on the day of the survey in hospital care units and involved interviews and observations. RESULTS: The study found that 30.04% of the health care workers knew the definition of healthcare-associated infections. Only 44.4% of the health care workers reported that the hands of health care workers (in the event of poor hand hygiene compliance) were the main mode of transmission of germs between patients in a care facility. In addition, only 21.43% (12/56) of the participants were aware of the main factors that increase the risk of health care-associated infections. The level of compliance with hygiene protocols was low (36.85%). CONCLUSION: The promotion of patient safety and quality of care requires a focus on training and behavior change among health care workers.