Alain Michault

University of La Réunion, Saint-Denis, Réunion, Reunion

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Publications (142)333.64 Total impact

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    ABSTRACT: Objectives: To estimate the cumulative incidence rate (CIR) of Chikungunya virus (CHIKV)-associated Central Nervous System (CNS) disease during the La Réunion outbreak, and assess the disease burden and patient outcome after three years.Methods: CHIKV-associated CNS disease was characterized retrospectively in a cohort of patients with positive CHIKV RT-PCR or anti-CHIKV IgM antibodies in the cerebrospinal fluid and fulfilling International Encephalitis Consortium criteria for encephalitis or encephalopathy. Neurological sequelae were assessed after three years.Results: Between September 2005 and June 2006, 57 patients were diagnosed with CHIKV-associated CNS disease, including 24 with CHIKV-associated encephalitis, the latter corresponding to a CIR of 8.6 per 100,000 persons. Patients with encephalitis were observed at both extremes of age categories. CIR per 100,000 persons were 187 and 37 in patients below 1 year and over 65 years, respectively, both far superior to those of cumulated causes of encephalitis in the USA in these age categories. The case fatality rate of CHIKV-associated encephalitis was 16.6% and the proportion of children discharged with persistent disabilities estimated between 30% and 45%. Beyond the neonatal period, the clinical presentation and outcomes were less severe in infants than in adults.Conclusions: In the context of a large outbreak, CHIKV is a significant cause of CNS disease. As with other etiologies, CHIKV-associated encephalitis case distribution by age follows a U-shaped parabolic curve.
    No preview · Article · Jan 2016 · Neurology
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    DESCRIPTION: E-Q-RUN - Epidémiologie de la fièvre Q dans le Sud de La Réunion : séroprévalence, incidence, déterminants et aspects cliniques. Projet de PHRC interrégional sur l'épidémiologie des infections à Coxiella burnetii estimant la séroprévalence en population générale à partir des mesures réalisées chez la femme enceinte, de la structure de la population et des taux d'attaque. Projet non financé au PHRC-I 2012 mais financé l'année suivante à l'APIDOM 2013.
    Full-text · Research · Nov 2015
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    DESCRIPTION: EMERUN - Epidémiologie des méningo-encéphalites dans le Sud de La Réunion : incidence, étiologies, aspects cliniques et pronostiques Projet de PHRC national sur l'épidémiologie des infections neuro-invasives (méningite, encéphalite, méningo-encéphalite) à l'île de la Réunion, non financé.
    Full-text · Research · Sep 2015

  • No preview · Article · Aug 2015

  • No preview · Article · Aug 2015 · Veterinary Parasitology
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    ABSTRACT: Taenia solium cysticercosis was reported in official veterinary and medical statistics to be highly prevalent in pigs and humans in Madagascar, but few estimates are available for pigs. This study aimed to estimate the seroprevalence of porcine cysticercosis among pigs slaughtered in Antananarivo abattoirs. Firstly, the diagnostic performance of two antigen-ELISA techniques (B158B60 Ag-ELISA and HP10 Ag-ELISA) and an immunoblotting method were compared with meat inspection procedures on a sample of pigs suspected to be infected with (group 1; n = 250) or free of (group 2; n = 250) T. solium based on direct veterinary inspection in Madagascar. Sensitivity and specificity of the antigen ELISAs were then estimated using a Bayesian approach for detection of porcine cysticercosis in the absence of a gold standard. Then, a third set of pig sera (group 3, n=250) was randomly collected in Antananarivo slaughterhouses and tested to estimate the overall prevalence of T. solium contamination in pork meat traded in Antananarivo. The antigen ELISAs showed a high sensitivity (>84%), but the B158B60 Ag-ELISA appeared to be more specific than the HP10 Ag-ELISA (model 1: 95% vs 74%; model 2: 87% vs 71%). The overall prevalence of porcine cysticercosis in Antananarivo slaughterhouses was estimated at 2.3% (95% credibility interval [95%CrI]: 0.09-9.1%) to 2.6% (95%CrI: 0.1-10.3%) depending on the model and priors used. Since the sample used in this study is not representative of the national pig population, village-based surveys and longitudinal monitoring at slaughter are needed to better estimate the overall prevalence, geographical patterns and main risk factors for T. solium contamination, in order to improve control policies.
    Full-text · Article · Aug 2015 · Veterinary Parasitology
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    ABSTRACT: We report herein the investigation of a leptospirosis outbreak occurring in triathlon competitors on Réunion Island, Indian Ocean. All participants were contacted by phone or email and answered a questionnaire. Detection and molecular characterization of pathogenic Leptospira was conducted in inpatients and in rodents trapped at the vicinity of the event. Of the 160 athletes competing, 101 (63·1%) agreed to participate in the study. Leptospirosis was biologically confirmed for 9/10 suspected cases either by real-time PCR or serological tests (MAT or ELISA). The total attack rate, children's attack rate, swimmers’ attack rate, and the attack rate in adult swimmers were respectively estimated at 8·1% [95% confidence interval (CI) 4·3–14·7], 0%, 12·7% (95% CI 6·8–22·4) and 23·1% (95% CI 12·6–33·8). Leptospirosis cases reported significantly more wounds [risk ratio (RR) 4·5, 95% CI 1·6–13], wore complete neoprene suits less often (RR 4·3, 95% CI 1·3–14·5) and were most frequently unlicensed (RR 6·6, 95% CI 2·9–14·8). The epidemiological investigation supported that some measures such as the use of neoprene suits proved efficient in protecting swimmers against infection. PCR detection in rats revealed high Leptospira infection rates. Partial sequencing of the 16S gene and serology on both human and animal samples strongly suggests that rats were the main contaminators and were likely at the origin of the infection in humans.
    No preview · Article · Jul 2015 · Epidemiology and Infection
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    ABSTRACT: Leptospirosis is a worldwide zoonosis that is endemic in tropical areas, such as Reunion Island. The species Leptospira interrogans is the primary agent in human infections, but other pathogenic species, such as L. kirschner and L. borgpetersenii, are also associated with human leptospirosis. In this study, a melting curve analysis of the products that were amplified with the primer pairs lfb1 F/R and G1/G2 facilitated an accurate species classification of Leptospira reference strains. Next, we combined an unsupervised high resolution melting (HRM) method with a new statistical approach using primers to amplify a two variable-number tandem-repeat (VNTR) for typing at the subspecies level. The HRM analysis, which was performed with ScreenClust Software, enabled the identification of genotypes at the serovar level with high resolution power (Hunter-Gaston index 0.984). This method was also applied to Leptospira DNA from blood samples that were obtained from Reunion Island after 1998. We were able to identify a unique genotype that is identical to that of the L. interrogans serovars Copenhageni and Icterohaemorrhagiae, suggesting that this genotype is the major cause of leptospirosis on Reunion Island. Our simple, rapid, and robust genotyping method enables the identification of Leptospira strains at the species and subspecies levels and supports the direct genotyping of Leptospira in biological samples without requiring cultures.
    Full-text · Article · Jul 2015 · PLoS ONE
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    ABSTRACT: Objective: To estimate the cumulative incidence rate (CIR) of Chikungunya virus (CHIKV)-associated CNS disease during the La Réunion outbreak, and assess the disease burden and patient outcome after 3 years. Methods: CHIKV-associated CNS disease was characterized retrospectively in a cohort of patients with positive CHIKV reverse transcriptase PCR or anti-CHIKV immunoglobulin M antibodies in the CSF and fulfilling International Encephalitis Consortium criteria for encephalitis or encephalopathy. Neurologic sequelae were assessed after 3 years. Results: Between September 2005 and June 2006, 57 patients were diagnosed with CHIKV-associated CNS disease, including 24 with CHIKV-associated encephalitis, the latter corresponding to a CIR of 8.6 per 100,000 persons. Patients with encephalitis were observed at both extremes of age categories. CIR per 100,000 persons were 187 and 37 in patients below 1 year and over 65 years, respectively, both far superior to those of cumulated causes of encephalitis in the United States in these age categories. The case-fatality rate of CHIKV-associated encephalitis was 16.6% and the proportion of children discharged with persistent disabilities estimated between 30% and 45%. Beyond the neonatal period, the clinical presentation and outcomes were less severe in infants than in adults. Conclusions: In the context of a large outbreak, CHIKV is a significant cause of CNS disease. As with other etiologies, CHIKV-associated encephalitis case distribution by age follows a U-shaped parabolic curve.
    No preview · Conference Paper · Jun 2015
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    ABSTRACT: Background: Leptospirosis is a widespread but underreported cause of morbidity and mortality. It has rarely been reported in either humans or animals in Madagascar. Methods: We conducted a cross-sectional survey of the inhabitants in Moramanga, Madagascar, in June 2011, to estimate the prevalence of human infection using the microscopic agglutination test (MAT). This activity was carried out as part of a workshop implemented by the Pasteur Institute of Madagascar, focusing on surveillance with a one week field study and targeting the health staff of the district level. Results: In total, we sampled 678 inhabitants from 263 households. The sex ratio (M/F) was 0.65 and the mean age 26.7 years. We obtained a value of 2.9% for the first recorded seroprevalence of this disease in the human community of Moramanga. Questionnaire responses revealed frequent contacts between humans and rodents in Moramanga. However, activities involving cattle were identified as a risk factor significantly associated with seropositivity (OR=3). Conclusion: Leptospirosis remains a neglected disease in Madagascar. This study highlights the need to quantify the public health impact of this neglected disease in a more large scale, in all the country and to establish point-of-care laboratories in remote areas.
    Full-text · Article · Apr 2015 · PLoS ONE
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    ABSTRACT: This report describes the first known laboratory-confirmed case of Mycobacterium fortuitum breast infection related to the hospital water supply. The source of the M fortuitum infection was identified by repetitive extragenic palindromic sequence-based polymerase chain reaction genotyping. In addition, we discuss appropriate infection control measures to minimize patient exposure to waterborne pathogens, in particular, in the context of nontuberculous mycobacteria, which is difficult to eradicate from the water supply network. Copyright © 2015 Association for Professionals in Infection Control and Epidemiology, Inc. Published by Elsevier Inc. All rights reserved.
    No preview · Article · Apr 2015 · American journal of infection control
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    Full-text · Dataset · Mar 2015
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    ABSTRACT: The 2014 seasonal influenza in Réunion, a French overseas territory in the southern hemisphere, was dominated by influenza B. Resulting morbidity impacted public health. Relative to the total number of all-cause consultations over the whole season, the rate of acute respiratory infection (ARI) consultations was 6.5%. Severe disease occurred in 32 laboratory-confirmed influenza cases (31.7 per 100,000 ARI consultations), 16 with influenza B. The observed disease dynamics could present a potential scenario for the next European influenza season.
    No preview · Article · Oct 2014 · Eurosurveillance: bulletin europeen sur les maladies transmissibles = European communicable disease bulletin
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    ABSTRACT: Unlabelled: Chikungunya virus (CHIKV) is a reemerging alphavirus that causes a debilitating arthritic disease and infects millions of people and for which no specific treatment is available. Like many alphaviruses, the structural targets on CHIKV that elicit a protective humoral immune response in humans are poorly defined. Here we used phage display against virus-like particles (VLPs) to isolate seven human monoclonal antibodies (MAbs) against the CHIKV envelope glycoproteins E2 and E1. One MAb, IM-CKV063, was highly neutralizing (50% inhibitory concentration, 7.4 ng/ml), demonstrated high-affinity binding (320 pM), and was capable of therapeutic and prophylactic protection in multiple animal models up to 24 h postexposure. Epitope mapping using a comprehensive shotgun mutagenesis library of 910 mutants with E2/E1 alanine mutations demonstrated that IM-CKV063 binds to an intersubunit conformational epitope on domain A, a functionally important region of E2. MAbs against the highly conserved fusion loop have not previously been reported but were also isolated in our studies. Fusion loop MAbs were broadly cross-reactive against diverse alphaviruses but were nonneutralizing. Fusion loop MAb reactivity was affected by temperature and reactivity conditions, suggesting that the fusion loop is hidden in infectious virions. Visualization of the binding sites of 15 different MAbs on the structure of E2/E1 revealed that all epitopes are located at the membrane-distal region of the E2/E1 spike. Interestingly, epitopes on the exposed topmost and outer surfaces of the E2/E1 trimer structure were neutralizing, whereas epitopes facing the interior of the trimer were not, providing a rationale for vaccine design and therapeutic MAb development using the intact CHIKV E2/E1 trimer. Importance: CHIKV is the most important alphavirus affecting humans, resulting in a chronic arthritic condition that can persist for months or years. In recent years, millions of people have been infected globally, and the spread of CHIKV to the Americas is now beginning, with over 100,000 cases occurring in the Caribbean within 6 months of its arrival. Our study reports on seven human MAbs against the CHIKV envelope, including a highly protective MAb and rarely isolated fusion loop MAbs. Epitope mapping of these MAbs demonstrates how some E2/E1 epitopes are exposed or hidden from the human immune system and suggests a structural mechanism by which these MAbs protect (or fail to protect) against CHIKV infection. Our results suggest that the membrane-distal end of CHIKV E2/E1 is the primary target for the humoral immune response to CHIKV, and antibodies targeting the exposed topmost and outer surfaces of the E2/E1 trimer determine the neutralizing efficacy of this response.
    Full-text · Article · Oct 2014 · Journal of Virology
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    ABSTRACT: Author Summary Q fever is a disease that could be transmitted from animals (cattle, sheep and goats) to humans and caused by a bacterium called Coxiella burnetii (C. burnetii). Some human cases exhibiting characteristic clinical signs of that disease have been detected on Reunion Island, a tropical island in the Indian Ocean, but to date, we did not know if these animals could be seen as potential sources of the disease. Thus, a study was undertaken from March 2011 to August 2012 to detect the presence of that bacterium in these animals and to understand how they could get infected themselves. A total of 516 ruminants (245 cattle, 137 sheep and 134 goats) belonging to 71 farms and localized in different environments of the island were selected. Samples of blood, vaginal mucus and milk were concomitantly collected from females, and a questionnaire was submitted to the farmers. Ticks from positively detected farms were also collected. We observed 11.8% of cattle, 1.4% of sheep and 13.4% of goats had already been in contact with the bacterium. Coxiella burnetii was also directly detected in some vaginal and milk samples. None of the ticks were detected to be positive for C. burnetii. We found that the ruminants could be infected when their farm was exposed to prevailing winds because the bacterium can be transported by the wind, and when there were no specific precautions for visitors before entering the farm, because they could act as mechanical carriers of Coxiella. Conversely, keeping new animals under surveillance for some days to detect any signs of the disease before they enter the farm or keeping the animals in the barn at night limit the risk of infection.
    Full-text · Article · Aug 2014 · PLoS Neglected Tropical Diseases
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    ABSTRACT: Abstract BACKGROUND: Little is known about the neurocognitive outcome in children exposed to perinatal mother-to-child Chikungunya virus (p-CHIKV) infection. METHODS: The CHIMERE ambispective cohort study compared the neurocognitive function of 33 p-CHIKV-infected children (all but one enrolled retrospectively) at around two years of age with 135 uninfected peers (all enrolled prospectively). Psychomotor development was assessed using the revised Brunet-Lezine scale, examiners blinded to infectious status. Development quotients (DQ) with subscores covering movement/posture, coordination, language, sociability skills were calculated. Predictors of global neurodevelopmental delay (GND, DQ ≤ 85), were investigated using multivariate Poisson regression modeling. Neuroradiologic follow-up using magnetic resonance imaging (MRI) scans was proposed for most of the children with severe forms. RESULTS: The mean DQ score was 86.3 (95%CI: 81.0-91.5) in infected children compared to 100.2 (95%CI: 98.0-102.5) in uninfected peers (P<0.001). Fifty-one percent (n = 17) of infected children had a GND compared to 15% (n = 21) of uninfected children (P<0.001). Specific neurocognitive delays in p-CHIKV-infected children were as follows: coordination and language (57%), sociability (36%), movement/posture (27%). After adjustment for maternal social situation, small for gestational age, and head circumference, p-CHIKV infection was found associated with GND (incidence rate ratio: 2.79, 95%CI: 1.45-5.34). Further adjustments on gestational age or breastfeeding did not change the independent effect of CHIKV infection on neurocognitive outcome. The mean DQ of p-CHIKV-infected children was lower in severe encephalopathic children than in non-severe children (77.6 versus 91.2, P<0.001). Of the 12 cases of CHIKV neonatal encephalopathy, five developed a microcephaly (head circumference <-2 standard deviations) and four matched the definition of cerebral palsy. MRI scans showed severe restrictions of white matter areas, predominant in the frontal lobes in these children. CONCLUSIONS: The neurocognitive outcome of children exposed to perinatal mother-to-child CHIKV infection is poor. Severe CHIKV neonatal encephalopathy is associated with an even poorer outcome.
    Full-text · Article · Jul 2014 · PLoS Neglected Tropical Diseases
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    Full-text · Article · Jun 2014 · Médecine et Maladies Infectieuses
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    Full-text · Article · Apr 2014 · Emerging Infectious Diseases
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    ABSTRACT: Since 1953, leptospirosis has been recognized as a public health problem on Reunion Island. In 2004, was implemented a specific surveillance system that included systematic reporting and the realization of environmental investigations around hospitalized cases. Here, we present the synthesis of historical data and the assessment of 9 years of leptospirosis surveillance. From 2004 to 2012, 414 hospitalized cases were reported. Cases of leptospirosis occurred mostly during the rainy season from December to May. Approximately 41% of infections occurred at home, 12% of infections occurred during aquatic leisure and 5% of cases were linked to professional activities. Furthermore, for 41% of cases, the place of infection could not be determined due to the accumulation of residential and non-residential exposure. Most of the cases of leptospirosis were linked to rural areas or traditional, rural occupations. We did not observe a shift to recreational leptospirosis as described in some developed countries. According to the new surveillance system, the number of reported cases has regularly increased since 2004. This situation is in part due to the improvement of the system in the first years but also to a real increase in the number of detected cases due to the introduction of molecular methods and to increased biological investigation into the Dengue-like syndrome by medical practitioners on the island since the Chikungunya crisis in 2006. This increase is probably due to surveillance and diagnosis biases but need to be carefully monitored. Nevertheless, the possibility of an outbreak is always present due to climatic events, such as after the "hyacinth" hurricane in 1980.
    Full-text · Article · Jan 2014 · International Journal of Environmental Research and Public Health
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    ABSTRACT: Immunity against dengue virus (DENV) on Reunion Island could play an important role in the risk of dengue outbreaks but is rather unknown. A study was performed to estimate seroprevalence of antibodies against DENV among blood donors. An age- and sex-stratified sample of 1825 sera was randomly selected. Overall seroprevalence was 3.1% (95% CI: 2.2-3.9%); seroprevalence increased with age and was much higher in women than in men. The low level of herd immunity is consistent with the absence of an endemic circulation of DENV, and makes it probable that Reunion Island will face future outbreaks.
    No preview · Article · Dec 2013 · Transactions of the Royal Society of Tropical Medicine and Hygiene

Publication Stats

3k Citations
333.64 Total Impact Points

Institutions

  • 2010-2015
    • University of La Réunion
      • • Infectious Diseases Research Group (GRI)
      • • Plant Communities and Biological Invaders in Tropical Environment (PVBMT)
      Saint-Denis, Réunion, Reunion
    • Centre Hospitalier Universitaire de la Réunion
      Saint-Paul, Réunion, Reunion
    • Centre Hospitalier de Saint Denis
      Saint-Denis-de Pilles, Aquitaine, France
  • 2014
    • University Hospital Estaing of Clermont-Ferrand
      Clermont, Auvergne, France
  • 2006-2014
    • Groupe Hospitalier Est Réunion (GHER)
      Санкт-Бенуа, Réunion, Reunion
  • 2013
    • Centre Hospitalier Universitaire de Dijon
      Dijon, Bourgogne, France