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

Simultaneous detection and quantification of Chikungunya, Dengue and West Nile viruses by multiplex RT-PCR assays and Dengue virus typing using High Resolution Melting

International audienceChikungunya (CHIKV), Dengue (DENV) and West Nile (WNV) viruses are arthropod-borne viruses that are able to emerge or re-emerge in many regions due to climatic changes and increase in travel. Since these viruses produce similar clinical signs it is important for physicians and epidemiologists to differentiate them rapidly. A molecular method was developed for their detection and quantitation in plasma samples and a DENV typing technique were developed. The method consisted in performing two multiplex real-time one-step RT-PCR assays, to detect and quantify the three viruses. Both assays were conducted in a single run, from a single RNA extract containing a unique coextracted and coamplified composite internal control. The quantitation results were close to the best detection thresholds obtained with simplex RT-PCR techniques. The differentiation of DENV types was performed using a High Resolution Melting technique. The assays enable the early diagnosis of the three arboviruses during viremia, including cases of coinfection. The method is rapid, specific and highly sensitive with a potential for clinical diagnosis and epidemiological surveillance. A DENV positive sample can be typed conveniently using the High Resolution Melting technique using the same apparatus

Development of a sensitive real-time reverse transcriptase PCR assay with an internal control to detect and quantify chikungunya virus

International audienceBackground: The chikungunya virus (CHIKV; Alphavirus, Togaviridae) has emerged in the south Western Indian Ocean since early 2005. A major outbreak of CHIKV infection occurred in Reunion Island, where the virus is transmitted by Aedes albopictus mosquitoes. Facing an outbreak of unprecedented magnitude, we developed a rapid, sensitive, and reliable assay for the detection and quantification of CHIKV in plasma samples. Methods: A dual-color TaqMan 1-step reverse transcriptase PCR assay was developed in a LightCycler 2.0 system. A coextd. and coamplified chimerical RNA sequence was used as an internal control (IC) to eliminate false-neg. results. The CHIKV-specific and IC probes were labeled with 6-carboxyfluorescein (530 nm) and the wide span dye DYXL (705 nm), resp., eliminating the need for color compensation. A synthetic RNA was used as an external calibrator for CHIKV abs. quantification. Results: The detection limit was 350 copies/mL (3 copies/capillary). A further improvement to ∼40 copies/mL was obtained by use of a larger vol. of plasma. The assay specificity was confirmed in vitro and in silico. CHIKV in 343 patients was present at viral loads \textgreater108 copies/mL, mainly in newborns and seniors \textgreater60 years old. Long viremic phases of up to 12 days were seen in 6 patients. Conclusions: The assay is rapid, CHIKV-specific, and highly sensitive, and it includes an IC. It proved useful to detect and quantify CHIKV during the Reunion Island epidemic. The assay might be applicable to other CHIKV epidemics, esp. in the Indian subcontinent, where an extensive outbreak is ongoing. [on SciFinder(R)

Chikungunya virus-associated encephalitis: a cohort study on La Réunion island, 2005-2009

International audienceObjectives: 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

Biological parameters.

<p><b><i>Group A1: RT PCR CHIKV positive patients. Group A2: RT PCR CHIKV negative, IgM anti CHIKV positive, IgG anti CHIKV negative patients. Group B: RT PCR CHIKV negative, IgM anti CHIKV negative, IgG anti CHIKV negative patients.</i></b></p><p><b><i>Group A1 vs. Group A2: ^¤¤¤ p<0.001, ^¤¤ p<0.01, ^¤ p<0,05.</i></b></p><p><b><i>Group A1 vs. Group B:</i></b> *** <b><i>p<0.001, ** p<0.01, * p<0,05.</i></b></p><p><b><i>Average, standard deviation, percentage in parenthesis are indicated.</i></b></p><p>^#<b><i>Physiological ranges.</i></b></p

Clinical signs.

<p><b><i>Group A1: RT PCR CHIKV positive patients. Group A2: RT PCR CHIKV negative, IgM anti CHIKV positive, IgG anti CHIKV negative patients. Group B: RT PCR CHIKV negative, IgM anti CHIKV negative, IgG anti CHIKV negative patients.</i></b></p><p><b><i>Group A1 vs Group A2: ^¤¤¤ p<0.001, ^¤¤ p<0.01, ^¤ p<0,05.</i></b></p><p><b><i>Group A1 vs. Group B:</i></b> *** <b><i>p<0.001, ** p<0.01, * p<0,05.</i></b></p><p><b><i>Average, standard deviation, percentage in parenthesis are indicated.</i></b></p

Demographic data.

<p><b><i>Group A1: RT PCR CHIKV positive patients. Group A2: RT PCR CHIKV negative, IgM anti CHIKV positive, IgG anti CHIKV negative patients. Group B: RT PCR CHIKV negative, IgM anti CHIKV negative, IgG anti CHIKV negative patients.</i></b></p><p><b><i>Group A1 vs. Group A2: ^¤¤¤ p<0.001, ^¤¤ p<0.01, ^¤ p<0,05.</i></b></p><p><b><i>Group A1 vs. Group B:</i></b> *** <b><i>p<0.001, ** p<0.01, * p<0,05.</i></b></p><p><b><i>Average, standard deviation, percentage in parenthesis are indicated.</i></b></p

Arthralgia location.

<p><b><i>Group A1: RT PCR CHIKV positive patients. Group A2: RT PCR CHIKV negative, IgM anti CHIKV positive, IgG anti CHIKV negative patients. Group B: RT PCR CHIKV negative, IgM anti CHIKV negative, IgG anti CHIKV negative patients.</i></b></p><p><b><i>Group A1 vs. Group A2: ^¤¤¤ p<0.001, ^¤¤ p<0.01, ^¤ p<0,05.</i></b></p><p><b><i>Group A1 vs. Group B:</i></b> *** <b><i>p<0.001, ** p<0.01, * p<0,05.</i></b></p><p><b><i>Average, standard deviation, percentage in parenthesis are indicated.</i></b></p

Cutaneomucosal signs.

<p><b><i>Group A1: RT PCR CHIKV positive patients. Group A2: RT PCR CHIKV negative, IgM anti CHIKV positive, IgG anti CHIKV negative patients. Group B: RT PCR CHIKV negative, IgM anti CHIKV negative, IgG anti CHIKV negative patients.</i></b></p><p><b><i>Group A1 vs. Group A2: ^¤¤¤ p<0.001, ^¤¤ p<0.01, ^¤ p<0,05.</i></b></p><p><b><i>Group A1 vs. Group B:</i></b> *** <b><i>p<0.001, ** p<0.01, * p<0,05.</i></b></p><p><b><i>Average, standard deviation, percentage in parenthesis are indicated.</i></b></p

A review of the dynamics and severity of the pandemic A(H1N1) influenza virus on Réunion Island, 2009

International audienceClin Microbiol Infect 2010; 16: 309–316 Abstract On Reunion Island, in response to the threat of emergence of the pandemic influenza A(H1N1)2009 virus, we implemented enhanced influenza surveillance from May 2009 onwards in order to detect the introduction of pandemic H1N1 influenza and to monitor its spread and impact on public health. The first 2009 pandemic influenza A(H1N1) virus was identified in Réunion on July 5, 2009, in a traveller returning from Australia; seasonal influenza B virus activity had already been detected. By the end of July, a sustained community pandemic virus transmission had been established. Pandemic H1N1 influenza activity peaked during week 35 (24–30 August 2009), 4 weeks after the beginning of the epidemic. The epidemic ended on week 38 and had lasted 9 weeks. During these 9 weeks, an estimated 66 915 persons who consulted a physician could have been infected by the influenza A(H1N1)2009 virus, giving a cumulative attack rate for consultants of 8.26%. Taking into account the people who did not consult, the total number of infected persons reached 104 067, giving a cumulative attack rate for symptomatics of 12.85%. The crude fatality rate (CFR) for influenza A(H1N1)2009 and the CFR for acute respiratory infection was 0.7/10 000 cases. Our data show that influenza pandemic did not have a health impact on overall mortality on Réunion Island. These findings demonstrate the value of an integrated epidemiological, virological and hospital surveillance programme to monitor the scope of an epidemic, identify circulating strains and provide some guidance to public health control measures