Geographic distribution and developmental sites of Aedes albopictus (Diptera: Culicidae) during a Chikungunya epidemic event.

Aedes albopictus is generally considered to have a low vectorial capacity because of its lack of host specificity. Nevertheless, it has been the sole vector of the Chikungunya virus in recent explosive epidemics on the islands of La Réunion and Mauritius. We report on investigations of the seasonal prevalence, container preferences, and geographic distribution of the species on La Réunion. Ae. albopictus showed strong ecological plasticity. In the warm wet season, small disposable containers were the principal urban breeding site, with 1939 positive containers in 750 houses. In the dry winter season, the species remained abundant throughout the island up to 800 m and was present to a maximum altitude of 1200 m. Natural containers were clearly important in this season, although productive sources were hard to find. The preferred natural developmental sites were bamboo stumps and rock holes, over 357 developmental sites observed in peri-urban and gully areas. Generalized logistic models indicated that the optimum sites contained clear water with high organic content and were situated in sites with moderate shade. Our data will provide input into the models of the epidemiology of the disease and design of vector control programs.

On a temporal model for the Chikungunya disease: modeling, theory and numerics.

Reunion Island faced two episodes of Chikungunya, a vector-borne disease, in 2005 and in 2006. The latter was of unprecedented magnitude: one third of the population was infected. Until the severe episode of 2006, our knowledge of Chikungunya was very limited. The principal aim of our study is to propose a model, including human and mosquito compartments, that is associated to the time course of the first epidemic of Chikungunya. By computing the basic reproduction number R(0), we show there exists a disease-free equilibrium that is locally asymptotically stable if the basic reproduction number is less than 1. Moreover, we give a necessary condition for global asymptotic stability of the disease-free equilibrium. Then, we propose a numerical scheme that is qualitatively stable and present several simulations as well as numerical estimates of the basic reproduction number for some cities of Reunion Island. For the episode of 2005, R(0) was less than one, which partly explains why no outbreak appeared. Using recent entomological results, we investigate links between the episode of 2005 and the outbreak of 2006. Finally, our work shows that R(0) varied from place to place on the island, indicating that quick and focused interventions, like the destruction of breeding sites, may be effective for controlling the disease.

Relapses in hepatoblastoma patients: clinical characteristics and outcome--experience of the International Childhood Liver Tumour Strategy Group (SIOPEL).

PURPOSE: To analyse the clinical characteristics and outcome of hepatoblastoma (HB) patients who relapsed after enrolment on SIOPEL studies 1-3. PATIENTS AND METHODS: Analysis of clinical data of all 59 patients (pts) registered in SIOPEL 1-3 studies, who relapsed after achieving complete remission (CR). RESULTS: The median time from the initial diagnosis to relapse was 12 months (4-115 m). The site of relapse was lung N=27, liver N=21, both liver and lung N=5 and other N=5 (missing data-MD: 1 patient). All but 9 pts had an alpha-fetoprotein level >10 ng/mL at the time of relapse. Treatment of the relapse included chemotherapy and surgery N=25, chemotherapy alone N=21, surgery alone N=7 and only palliative treatment N=5 (MD: 1 pt). Overall, 31 pts (52%) achieved a second CR. With a median follow-up of 83 months, 23 pts are alive, (18 in 2nd CR, 5 after a second relapse) and 36 pts have died (35 from disease and 1 from complications). Three-year event-free survival and overall survival are 34% and 43% respectively (95% confidence interval [CI] 0.28-0.69). The main factors associated with a good outcome were PRETEXT group I-III at diagnosis, a high AFP level at relapse and relapse treatment including both chemotherapy and surgery. CONCLUSION: Relapses in HB are rare events occurring in less than 12% of pts after CR. Combined treatment with chemotherapy and surgical removal of the tumour is essential for long-term survival.