Leptospirosis in the western Indian Ocean islands: what is known so far?

International audience: In the past decade, leptospirosis has emerged as a major zoonosis with a worldwide distribution. The disease is caused by bacteria of the genus Leptospira. The western Indian Ocean includes more than one hundred tropical or subequatorial islands where leptospirosis constitutes a major public health problem. The clinical signs of the human disease are generally similar to an influenza-like syndrome, but acute forms of the disease are reported and mortality remains significant in this region. In animals, clinical forms are mainly asymptomatic but leptospirosis reduces the fertility of livestock, resulting in economic losses. The data available about human and animal leptospirosis in the western Indian Ocean islands are diverse: human leptospirosis has been extensively studied in Reunion Island, Mayotte, and the Seychelles, whereas the human clinical disease has never been described in Madagascar, Comoros, Mauritius, or Rodrigues, mainly because of the deficiency in appropriate medical and diagnostic structures. The rat is recognized as the major reservoir host for the bacteria on all islands, but recent data from Reunion Island indicates that almost all mammals can be a source of contamination. The incidence of leptospirosis in humans is highly seasonal, and linked to the rainy season, which is favorable for the environmental maintenance and transmission of the bacteria. The epidemiology of leptospirosis is fully island-dependent, related to the number of mammalian species, the origins of the introduced mammalian species, the relationships between humans and fauna, and environmental as well as cultural and socio-economic factors

Animal leptospirosis in small tropical areas

Leptospirosis is the most widespread zoonosis in the world. Humans become infected through contact with the urine of carrier animals, directly or via contaminated environments. This review reports available data on animal leptospirosis in ten tropical islands: Barbados, Martinique, Guadeloupe, Grenada, Trinidad, New Caledonia, Hawaii, French Polynesia, La Re´union and Mayotte. Leptospirosis is endemic in these insular wild and domestic fauna. Each island presents a specific panel of circulating serovars, closely linked with animal and environmental biodiversity, making it epidemiologically different from the mainland. Rats, mongooses and mice are proven major renal carriers of leptospires in these areas but dogs also constitute a significant potential reservoir. In some islands seroprevalence of leptospirosis in animals evolves with time, inducing changes in the epidemiology of the human disease. Consequently more investigations on animal leptospirosis in these ecosystems and use of molecular tools are essential for prevention and control of the human disease. (Résumé d'auteur

Emergence of Coxiella burnetii in Ruminants and Humans on Reunion Island: a new burden for public health? [P252]

Purpose Population growth, changes in food systems, urbanisation, and climate change linked in a web of global trade throw up new challenges for disease control. Animal health surveillance is widely recognized as an effective tool for disease management, but investment is often low and poorly targeted. For European decision-makers, economic criteria are important in decision-making for surveillance. Yet, economic evaluations of surveillance (EES) are sparse and available guidelines for the evaluation of surveillance fail to provide guidance on systematic economic appraisal. Methods The RISKSUR consortium (www.fp7-risksur.eu) that investigates novel approaches for cost-effective surveillance has developed a web-based surveillance design and evaluation tool directed at users with advanced surveillance knowledge and skills. A key innovative feature is the provision of user-friendly and practical guidance for the design and implementation of EES. Economic theory underpinning EES is explained and challenges that accrue from application of differing paradigms highlighted. In particular, the three-variable relationship between surveillance, intervention and loss avoidance; value of information, and non-monetary benefits are elaborated and linked to economic analysis methods commonly used in animal health. Results The application of the tool for EES for classical and African swine fever, bovine viral diarrhoea, avian influenza, and Salmonella Dublin infection in five European countries showed that cost-benefit, cost-effectiveness, and least-cost analyses were the methods of choice. Difficulties encountered include estimation of fixed and variable costs, non-monetary benefits, co-benefits resulting from using synergies, and the selection of meaningful effectiveness measures. Selected results will be presented. Conclusions and relevance The tool promotes understanding of critical concepts, suitable methods, data and time requirements and is expected to nurture the use of EES, which is still in its infancy. In the long term, this will increase professional capacity and help to address the problem of resource allocation for surveillance to the benefit of all. (Texte intégral

A Cross-Sectional Study of People with Epilepsy and Neurocysticercosis in Tanzania: Clinical Characteristics and Diagnostic Approaches.

Neurocysticercosis (NCC) is a major cause of epilepsy in regions where pigs are free-ranging and hygiene is poor. Pork production is expected to increase in the next decade in sub-Saharan Africa, hence NCC will likely become more prevalent. In this study, people with epilepsy (PWE, n=212) were followed up 28.6 months after diagnosis of epilepsy. CT scans were performed, and serum and cerebrospinal fluid (CSF) of selected PWE were analysed. We compared the demographic data, clinical characteristics, and associated risk factors of PWE with and without NCC. PWE with NCC (n=35) were more likely to be older at first seizure (24.3 vs. 16.3 years, p=0.097), consumed more pork (97.1% vs. 73.6%, p=0.001), and were more often a member of the Iraqw tribe (94.3% vs. 67.8%, p=0.005) than PWE without NCC (n=177). PWE and NCC who were compliant with anti-epileptic medications had a significantly higher reduction of seizures (98.6% vs. 89.2%, p=0.046). Other characteristics such as gender, seizure frequency, compliance, past medical history, close contact with pigs, use of latrines and family history of seizures did not differ significantly between the two groups. The number of NCC lesions and active NCC lesions were significantly associated with a positive antibody result. The electroimmunotransfer blot, developed by the Centers for Disease Control and Prevention, was more sensitive than a commercial western blot, especially in PWE and cerebral calcifications. This is the first study to systematically compare the clinical characteristics of PWE due to NCC or other causes and to explore the utility of two different antibody tests for diagnosis of NCC in sub-Saharan Africa

Séroprévalence de la cysticercose et facteurs de risque associés chez un groupe de patients vus au Centre Hospitalier Régional de Référence d’Antsirabe, Madagascar

Introduction: A Madagascar, la cysticercose, maladie causée par la forme larvaire de Taenia solium, demeure un problème de santé publique. En 2003, la séroprévalence de la cysticercose variait entre 7% et 21% avec un taux plus élevé dans les régions centrales de l’île. Toutefois, depuis une dizaine d’année, les données épidémiologiques concernant la cysticercose humaine restent limitées. Notre étude a pour objectif de déterminer, chez les patients issus de la région de Vakinankaratra et qui sont suspects cliniquement, la séroprévalence de la cysticercose par Western blot ainsi que les facteurs de risque associés. Méthodes: Il s’agit d’une étude descriptive transversale menée sur une période de 6 mois au sein du Centre Hospitalier Régional de Référence d’Antsirabe. Tous les patients inclus dans l’étude ont répondu à un questionnaire clinique recueillant leurs caractéristiques sociodémographiques et culturelles ainsi que leurs habitudes alimentaires et leurs symptômes cliniques. Résultats: La séroprévalence de la cysticercose retrouvée dans la population d’étude était de 14,8% (35/237). Ce taux ne diffère pas significativement selon le sexe, l’âge, la consommation de viande de porc ou le mode de préparation de la viande (p > 0,05). Par contre, une différence significative (p < 0,05) a été observée chez les sujets présentant des nodules sous-cutanés ou un résultat de cysticercose antérieur positif. Conclusion: L’index élevé d’exposition à Taenia solium retrouvé dans notre étude justifie le renforcement des mesures de contrôle et de prévention déjà implantés dans le pays

Prospective Study of Chikungunya Virus Acute Infection in the Island of La Réunion during the 2005–2006 Outbreak

BACKGROUND:Chikungunya virus (CHIKV) is a recently re-emerged arthropod borne virus responsible for a massive outbreak in the Indian Ocean and India, and extended to Southeast Asia as well as Italy. CHIKV has adapted to Aedes albopictus, an anthropophilic mosquito species widely distributed in Asia, Europe, Africa and America. Our objective was to determine the clinical and biological features of patients at the acute phase of CHIKV infection. METHODS AND FINDINGS:A prospective study enrolled 274 consecutive patients with febrile arthralgia recorded at the Emergency Department of the Groupe Hospitalier Sud-Réunion between March and May 2006. Three groups were defined: one group of 180 viremic patients (positive CHIKV RT-PCR), one group of 34 patients with acute post-viremic infection (negative CHIKV RT-PCR, positive anti-CHIKV IgM and negative IgG), and one group of 46 uninfected patients (negative CHIKV RT-PCR, anti-CHIKV IgM and IgG). Bivariate analyses of clinical and biological features between groups were performed. Patients with CHIKV viremia presented typically with asymmetrical bilateral polyarthralgia (96.5%) affecting the lower (98%) and small joints (74.8%), as well as asthenia (88.6%), headache (70%), digestive trouble (63.3%), myalgia (59%), exanthems (47.8%), conjunctival hyperhemia (23%) and adenopathy (8.9%). Vertigo, cutaneous dysesthesia, pharyngitis and haemorrhages were seldom observed. So far unreported symptoms such as chondrocostal arthralgia (20%), entesopathies (1.6%), talalgia (14%) were also noted. Prurit was less frequent during the viremic than post-viremic phase (13.9% vs. 41.2%; p<0.001), whereas lymphopenia was more frequent (87.6% vs. 39.4%; p<0.001). Others biological abnormalities included leukopenia (38.3%), thrombocytopenia (37.3%), increased ASAT and ALAT blood levels (31.6 and 7.3%, respectively) and hypocalcemia (38.7%). Lymphopenia <1,000/mm(3) was very closely associated with viremic patients (Yule coefficient 0.82, positive predictive value 92.3%). Age under 65 was associated with a benign course, as no patients younger than 65 had to be hospitalized (Yule coefficient 0.78). CONCLUSIONS:The diagnosis of CHIKV infection in acute phase is based on commonly accepted clinical criteria (fever and arthralgia), however clinical and biological diffrences exist in acute phase depending on whether or not the patient is within the viremic phase of the infection

Taenia solium porcine cysticercosis in Madagascar: Comparison of immuno-diagnostic techniques and estimation of the prevalence in pork carcasses traded in Antananarivo city

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. (Résumé d'auteur

Human leptospirosis on Reunion Island, Indian Ocean: are rodents the (only) ones to blame?

Background: Although leptospirosis is a zoonosis of major concern on tropical islands, the molecular epidemiology of the disease aiming at linking human cases to specific animal reservoirs has been rarely explored within these peculiar ecosystems. Methodology/Principal Findings: Five species of wild small mammals (n = 995) as well as domestic animals (n = 101) were screened for Leptospira infection on Reunion Island; positive samples were subsequently genotyped and compared to Leptospira from clinical cases diagnosed in 2012–2013 (n = 66), using MLST analysis. We identified two pathogenic species in human cases, namely Leptospira interrogans and Leptospira borgpetersenii. Leptospira interrogans was by far dominant both in clinical samples (96.6%) and in infected animal samples (95.8%), with Rattus spp and dogs being its exclusive carriers. The genetic diversity within L. interrogans was apparently limited to two sequence types (STs): ST02, identified among most clinical samples and in all rats with complete MLST, and ST34, identified in six humans, but not in rats. Noteworthy, L. interrogans detected in two stray dogs partially matched with ST02 and ST34. Leptospira borgpetersenii was identified in two clinical samples only (3.4%), as well as in cows and mice; four haplotypes were identified, of which two seemingly identical in clinical and animal samples. Leptospira borgpetersenii haplotypes detected in human cases were clearly distinct from the lineage detected so far in the endemic bat species Mormopterus francoismoutoui, thus excluding a role for this volant mammal in the local human epidemiology of the disease. Conclusions/Significance: Our data confirm rats as a major reservoir of Leptospira on Reunion Island, but also pinpoint a possible role of dogs, cows and mice in the local epidemiology of human leptospirosis. This study shows that a comprehensive molecular characterization of pathogenic Leptospira in both clinical and animal samples helps to gaining insight into leptospirosis epidemiology within a specific environmental setting

A226V Strains of Chikungunya Virus, Réunion Island, 2010

International audienceChikungunya virus (CHIKV) first emerged in Indian Ocean islands off the eastern coast of Africa in 2005 and was responsible for large-scale epidemics on the islands of Réunion, Comoros, Mayotte, Mauritius, Madagascar, and Seychelles (1–4). On Réunion Island, a French overseas territory of 810,000 inhabitants, herd immunity reached 38% in October 2006 (5). Molecular epidemiology of the strain responsible for these outbreaks indicated that it had originated in Kenya (6). The epidemic on Réunion Island was associated with a mutation in the envelope protein gene (E1-A226V) that improves replication and transmission efficiency in Aedes albopictus mosquitoes (7)

A Mouse Model for Chikungunya: Young Age and Inefficient Type-I Interferon Signaling Are Risk Factors for Severe Disease

Chikungunya virus (CHIKV) is a re-emerging arbovirus responsible for a massive outbreak currently afflicting the Indian Ocean region and India. Infection from CHIKV typically induces a mild disease in humans, characterized by fever, myalgia, arthralgia, and rash. Cases of severe CHIKV infection involving the central nervous system (CNS) have recently been described in neonates as well as in adults with underlying conditions. The pathophysiology of CHIKV infection and the basis for disease severity are unknown. To address these critical issues, we have developed an animal model of CHIKV infection. We show here that whereas wild type (WT) adult mice are resistant to CHIKV infection, WT mouse neonates are susceptible and neonatal disease severity is age-dependent. Adult mice with a partially (IFN-α/βR+/−) or totally (IFN-α/βR−/−) abrogated type-I IFN pathway develop a mild or severe infection, respectively. In mice with a mild infection, after a burst of viral replication in the liver, CHIKV primarily targets muscle, joint, and skin fibroblasts, a cell and tissue tropism similar to that observed in biopsy samples of CHIKV-infected humans. In case of severe infections, CHIKV also disseminates to other tissues including the CNS, where it specifically targets the choroid plexuses and the leptomeninges. Together, these data indicate that CHIKV-associated symptoms match viral tissue and cell tropisms, and demonstrate that the fibroblast is a predominant target cell of CHIKV. These data also identify the neonatal phase and inefficient type-I IFN signaling as risk factors for severe CHIKV-associated disease. The development of a permissive small animal model will expedite the testing of future vaccines and therapeutic candidates