Conceived and designed the experiments: FS FT. Performed the experiments: FS FT AS. Analyzed the data: FS PG ML AM. Contributed reagents/materials/analysis tools: IS KLR AM. Wrote the paper: FS ML AM.
The authors have declared that no competing interests exist.
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
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/mm3 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).
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.
Chikungunya virus (CHIKV) is a positive strand RNA enveloped alphavirus belonging to the
By including all patients referred to the Emergency Department (ED) with febrile arthralgia, the aim of this study was to describe prospectively the clinical and biological features of acute CHIKV infection and identify features to help differentiate CHIKV infection from other conditions. Using CHIKV-specific reverse transcription and polymerase chain reaction (RT-PCR) and serology, we also compared patients in the acute viremic phase and those in the post-viremic phase. We also investigated co-infections. Finally, we also identified clinical and biological markers for severity in acute CHIKV infection patients by comparing hospitalized patients to those who were not.
The prospective study was conducted in the ED of the Groupe Hospitalier Sud Réunion (GHSR) Regional Hospital. This hospital's standards are similar to those found in mainland France. It receives people living in the Southern part of the Island of La Réunion (350,000 inhabitants). The hospital has 1,154 beds and 316 physicians. The ED receives 41,000 patients annually; with adults being treated for medical and surgical conditions, and children for surgical conditions only.
We enrolled all patients over 15 years of age referred for febrile arthralgia at the ED between March 1st 2006 and May 31st 2006. A clinical examination, a blood sampling and a questionnaire were completed for all included subjects as the time of admission at the ED. This was the only time those patients were examined and interrogated for the purpose of this study.
The questionnaire was written after a 2-months observation period (January to February 2006, when the epidemic was at its peak, with an incidence of 45,000 cases per week). The questionnaire was created and validated after the medical file analysis of 1,030 consecutive patients referred to the ED with febrile arthralgia evocative of Chikungunya. The data collected included age, gender, medical history (co-morbidity, recent travels abroad), symptoms and date of their onset (1st day), the need for hospitalization and biological parameters.
Oral consent was obtained from each patient or a first-degree relative, as the investigations were carried out under the standard care procedure for this poorly characterized disease, in accordance with the recommendations of the Committee for Clinical Research of the GHSR. In France, written consent is mandatory only if the medical treatments or the products used are not standard for the diagnosis, treatment, or monitoring (
Chikungunya is known to evolve in successive phases: first, a viremic acute phase that lasts around 5 days, followed by a post-viremic acute phase defined by a negative CHIKV RT-PCR, presence of anti-CHIKV IgM antibodies but absence of IgG, that lasts about a week before the appearance of anti CHIKV IgG
Patients with positive anti-CHIKV IgG (
The study subjects were tested for other agents susceptible of causing fever and arthralgia. These include dengue and malaria (present in other islands of this area of the Indian Ocean) as well as leptospirosis, a prevalent infection in Reunion Island
Groups were compared using Chi-square or Fisher's exact test, when appropriate. Clinical and biological continuous parameters were compared with the Mann-Whitney test. Averages and standard deviation were calculated. A P value <0.05 was considered statistically significant.
In order to rationalize the choice of clinical and biological data for bivariate analysis, we looked for the sign with the highest correlation with a given group; the Yule coefficient was used to measure the strength of the link between the two variables (illness/sign). A Yule coefficient between 0.7 and 1 was considered as a very close link and 0.5–0.69 as a close link.
During the study (1st March 2006 - 31st May 2006), 9,656 patients were admitted at the ED; 274 displayed febrile arthralgia and were included in the study (
Among all patients admitted to the ED during the study, 2.21% were acutely infected by CHIKV and 1.86% were viremic. In acutely CHIKV-infected patients with fever and arthralgia (Group A), the positive predictive value of the presence of these two signs for CHIKV acute infection was 82.3%.
In Group A1, the average age did not significantly differ between men and women. Co-morbidity was more common in women (72.6 vs. 56.3%; p<0.05), particularly high blood pressure (50.0 vs. 33.3%; p<0.05) and diabetes mellitus (33.3 vs. 16.6%; p<0.05). Co-morbidity was more frequent in patients of 65 years and over (97.4 vs. 39.4%; p<0.001). No case of leptospirosis, dengue or malaria was diagnosed in this group.
Group A1 (n = 180) | Group A2 (n = 34) | Group B (n = 46) | |
55.7±21.7 | 54.5±19,8 | ||
15–96 | 17–89 | 16–93 | |
76 (42.2%) | 17 (50.0%) | ||
1,14 | 0.62 | 0.92 | |
115 (63.9%) | 24 (70.6%) | ||
74 (41.1%) | 15 (62.5%) | 3 (16.7%) | |
23 (12.8%) | 3 (12.5%) | 0 (0.0%) | |
17 (9.4%) | 0 (0.0%) | 1 (5.6%) | |
44 (24.4%) | 8 (33.3%) | 3 (16.7%) | |
27 (15.0%) | 3 (12.5%) | 1 (5.6%) | |
12 (6.7%) | 1 (2.9%) | 1 (5.6%) | |
21 (11.7%) | 2 (5.9%) | 2 (11.2%) | |
15 (8.3%) | 4 (16.7%) | 0 (0.0%) | |
14 (7.8%) | 4 (16.7%) | 1 (5.6%) | |
14 (7.8%) | 0 (0.0%) | 3 (16.7%) |
Group A1 (n = 180) | Group A2 (n = 34) | Group B (n = 46) | |
1.8±1.9 | |||
0–12 | 1–16 | 0–11 | |
39.1±0,86 | |||
35 (19.4%) | 6 (13.0%) | ||
23 (12.8%) | 3 (8.8%) | 5 (10.9%) | |
106 (58.9%) | 20 (58.8%) | 31 (67.4%) | |
126 (70.0%) | 20 (58.8%) | 36 (78.3%) | |
86 (47.8%) | 23 (67.7%) | ||
16 (8.9%) | 3 (6.5%) | ||
25 (13.9%) | 7 (15.2%) | ||
46 (25.6%) | 5 (10.9%) | ||
41(22.8%) | 6 (17.7%) | 6 (13.0%) | |
114 (63.3%) | |||
67 (58.8%) | 20 (69.0%) | 27 (73.0%) | |
49 (43.0%) | 11 (37.9%) | 22 (59.5%) | |
33 (28.9%) | 11 (37.9%) | 13 (35.1%) | |
80 (70.2%) | 25 (86.2%) | 23 (62.2%) | |
46 (40.4%) | 17 (58.6%) | 13 (35.1%) | |
36 (31.6%) | 5 (17.2%) | 15 (40.5%) | |
2 (1.1%) | 1 (2.2%) | ||
159 (88.3%) | 31 (91.2%) | ||
20 (11.1%) | 4 (11.8%) | 5 (10.9%) | |
9 (5.0%) | 0 (0.0%) | 2 (4.3%) | |
12 (6.7%) | 3(8.8%) | 1 (2.2%) | |
11 (6.1%) | 2 (5.9%) | 0 (0.0%) | |
14 (7.8%) | 0 (0.0%) | 5 (10.9%) |
Group A1 (n = 171) | Group A2 (n = 31) | Group B (n = 42) | |
155 (90.6%) | 26 (83.9%) | 36 (85.7%) | |
90 (52.6%) | 16 (51.6%) | 17 (40.5%) | |
81 (47.4%) | 19 (62.2%) | 12 (28.6%) | |
121 (59.7%) | 23 (74.2%) | ||
81 (47.4%) | 14 (45.2%) | 12 (28.6%) | |
86 (50.3%) | 17 (54.8%) | 23 (57.1%) | |
161 (94.1%) | 29 (93.4%) | 40 (95.2%) | |
83 (48.5%) | 18 (58.1%) | ||
130 (76.0%) | 26 (83.9%) | 28 (66.7%) | |
130 (76.0%) | 25 (80.6%) | 27 (64.3%) | |
29 (17.0%) | 2 (6.5%) | 7 (16.7%) | |
79 (46.2%) | 14 (45.2%) | 25 (59.5%) | |
37 (21.6%) | 5 (16.1%) | 11 (26.2%) | |
3 (1.8%) | 1 (3.2%) | 1 (2.4%) | |
169 (98.8%) | 30 (96.8%) | 40 (95.2%) | |
128 (74.8%) | 23 (74.2%) | 26 (61.9%) |
Group A1 (n = 180) | Group A2 (n = 34) | Group B (n = 46) | |
46 (25.6%) | 15 (44.1%)· | 5 (10.9%) | |
22 (47.8%) | 6 (40.0%) | 3 (60.0%) | |
12 (26.1%) | 5 (33.3%) | 2 (40.0%) | |
1 (2.2%) | 0 (0.0%) | 0 (0.0%) | |
10 (21.7%) | 3 (20.0%) | 1 (20.0%) | |
31 (67.4%) | 8 (53.3%) | 1 (20.0%) | |
4 (8.7%) | 0 (0.0%) | 0 (0.0%) |
Group A1 (n = 180) | Group A2 (n = 34) | Group B (n = 46) | |
86 (47.8%) | 23 (67.7%) | ||
16 (8.9%) | 1 (2.2%) | ||
70 (38.9%) | 12 (26.1%) | ||
26 (37.1%) | 3 (25.0%) | 4 (30.8%) | |
26 (37.1%) | 3 (25.0%) | 2 (15.4%) | |
45 (64.3%) | 8 (66.7%) | 7 (53.9%) | |
28 (40.0%) | 5 (41.7%) | 4 (30.8%) | |
19 (27.1%) | 3 (25.0%) | 1 (7.7%) | |
6 (8.6%) | 0 (0.0%) | 1 (7.7%) | |
9 (12.9%) | 4 (30.8%) | ||
18 (25.7%) | 5 (41.7%) | 2 (15.4%) | |
5 (7.1%) | 0 (0.0%) | 1 (7.7%) | |
4 (2.2%) | 3 (8.8%) | 0 (0.0%) | |
3 (1.7%) | 0 (0.0%) | 0 (0.0%) | |
25 (13,9%) | 7 (15.2%) | ||
8 (4.4%) | 2 (5.9%) | ||
7 (3.9%) | 0 (0.0%) | 0 (0.0%) | |
41 (22.8%) | 6 (17.7%) | 6 (13.0%) | |
0 (0.0%) | 1 (2.9%) | 0 (0.0%) | |
2 (1.1%) | 0 (0.0%) | 1 (7.7%) |
Most patients presented to the ED during the first 3 days after the onset of symptoms: 18.3% on the 1st day, 41.1% on the 2nd day, 18.3% on the 3rd day, and 10.0% on 4th day. The onset of symptoms was often described as abrupt, without prodromic phase. The highest body temperatures were recorded in patients who consulted within the 2 days that followed the onset of symptoms (1st day: 39.3±0.8°C; 2nd day: 39.2±0.9°C; 3rd day: 38.9±0.8°C; 4th day: 38.9±0.9°C; 5th day: 38.4±0.8°C; 1st day-2nd day vs. 5th day: p<0.05).
Data on osteoligamentous pain were available for 171 patients. The 9 remaining patients were disoriented, either acutely or chronically in the context of Alzheimer's disease, and although they complained from arthralgia, they were unable to describe them further. The joint symptoms were most often characterized by bilateral and symmetrical arthralgia (n = 165; 96.5%). In few cases, only 2 to 3 joints were affected (n = 4; 2.3%), and only two patients (1.2%) suffered from monoarthralgia. Impairment of the finger joints was more frequent in women than men (66.7 vs. 47.9%; p<0.01). Nineteen patients (10.5%) suffered from pain along previous bone fractures or ligaments injuries (tendinopathy, Achilles' tendon rupture) as well as increased arthrosic pain. Clinical examination revealed pain along ligament insertions (pubalgia, sternocleidomastoid and occipital insertions) in 3 patients (1.6%). Talalgia were observed in 24 patients (14.0%). Joint inflammatory signs were rare (n = 2; 1.1%) and peri-articular swellings were more frequent in women than men (36.9 vs. 15.6%; p<0.01).
Exanthema was either morbilliform, roseola-like, or more rarely maculopapular. An erysipela aspect of the lower limbs was reported in two patients (1.1%). Hemorrhagic signs were extremely rare and were not associated with clotting abnormalities or major thrombocytopenia. Uncommon neurological symptoms included cutaneous dysesthesia (n = 7; 3.9%) mostly of the sole of the feet, hallucinations (n = 2; 1.1%), paresthesia in the ulnar nerve territory (n = 1; 0.6%). Three patients (1.7%) presented with convulsion: one patient was epileptic, another one exhibited frequent comitial crises as stroke sequelae, and the last one suffered from alcohol withdrawal.
During the viremic phase of CHIKV infection, 3 patients (1.7%) decompensated a pre-existing cardiac insufficiency. Chest pain was associated with pericarditis (n = 2; 1.1%), acute coronary syndrome (n = 4; 2.2%), and myocarditis (n = 2; 1.1%). The registered cardiac arrhythmias (atrial fibrillation n = 4, ventricular extra systole n = 2) were pre-existing conditions. Dyspnoea was observed in 17 patients (9.4%), who were older than the average age (71 year-old) and affected with respiratory or cardiac disorders or complications (acute pneumopathy). Two patients of 15 and 18 year-old complained from abdominal pain and displayed clinical signs of mesenteric lymphadenitis associated with peripheral adenopathies.
The blood platelet counts were lower for patients examined on 5th day (134,143±33,354/mm3) than for patients examined on 1st day (195,813±51,859/mm3; p<0.01) or 2nd day (183,068±53,996/mm3; p<0.05). During the viremic phase, the average blood lymphocytes values were under the normal range, without significant difference compared to the onset of symptoms.
Groupe A1 (n = 180) | Groupe A2 (n = 34) | Groupe B (n = 46) | |
174288±55962 | 173735±62235 | 193444±92057 | |
(150000–500000/mm3) |
(38000–355000) | (46000–330000) | (26000–579000) |
5,431±2,139 | 5,199±2,554 | ||
(4500–13500/mm3) |
(1,900–14,800) | (1,400–12,400) | (1,700–16,600) |
608±314 | |||
(1000–4000/mm3) |
(100–2,360) | (300–2,500) | (200–3,400) |
6.8±4.9 | 6.1±3.2 | 5.8±4.401 | |
(2.5–7.5 mmol/L) |
(1.6–37.0) | (2.6–16.0) | (2.3–27.6) |
111,1±73,1 | 104.2±100.9 | ||
(50–100 mmol/L) |
(40.0–604.0) | (53.0–661.0) | (35.0–328.0) |
55.9±50.4 | 73.3±108.5 | ||
(<2.5 mg/L) |
(0.0–351.0) | 0.0–267.0) | (0.0–492.0) |
2.28±0.14 | 2.31±0.12 | ||
(2.25–2.65 mmol/L) |
(1.8–2.7) | (2.05–2.66) | (1.96–2.75) |
55.0±164.0 | 53.2±42.3 | 333.2±1952.8 | |
(<45 UI/L) |
(12.0–2177.0) | (16.0–195.0) | (13.0–13140.0) |
35.2±89.7 | 122.9±651.4 | ||
(<65 UI/L) |
(7.0–1189.0) | (11.0–125.0) | (8.0–4394.0) |
320.6±794.3 | 334.6±630.7 | 291.6±542.7 | |
(<210 UI/L) |
(22.0–7608.0) | (25.0–2901.0) | (28.0–3209.0) |
42.5±29.3 | 42.3±19.9 | ||
(<60 UI/L) |
(9.0–202.0) | (15.0–101.1) | (9.0–180.0) |
#
A significant difference for the blood biological parameters between genders was found for platelets (men 161,298±49,050/mm3; women 189,000±59,838/mm3; p<0.01), creatinine (men 117.4±60.9 mmol/L; women 104.1±84.5 mmol/L; p<0.001), alanine aminotransferase (men 31.8±22.4 UI/L; women 38.8±128.4 UI/L; p<0.01) and creatine phosphokinase (men 361±874 UI/L; women 275.0±696.0 UI/L; p<0.01).
Viral load was significantly higher in patients with comorbidity than those without (2.29 106±11.9 106 vs. 3.04 105±7.48 105 copies/mL; p<0.05). Viral load was also significantly higher in patients 65 year-old and older than in patients less than 65 year-old (3.86 105±11.99 105 vs. 3.19 106±14.55 106 copies/mL; p<0.001).
Sixty-nine patients (32.2%) were hospitalized. Two patients (83 and 73 year-old) died while they were hospitalized because of a nosocomial
Age over 65 was the factor most associated with severity (Yule coefficient 0.78, sensitivity 74.6%, specificity 73.0%, positive predictive value 57.9% negative predictive value 85.6%).
The diagnoses in Group B differed, depending on whether the patients had to be hospitalized or not. For non-hospitalized patients (n = 33), suspicion of CHIKV infection was the diagnosis most frequently mentioned but not confirmed biologically later on (n = 25) (no alternative diagnosis was later obtained); other diagnoses were malaria (n = 2), pyelonephritis (n = 4), gastroenteritis (n = 1), pharyngitis (n = 1). Among hospitalized patients (n = 13), diagnoses were pneumopathy (n = 4), pyelonephritis (n = 3), leptospirosis (n = 2), gastroenteritis (n = 1), migraine (n = 1), fulminant hepatitis of unknown origin (n = 1), microcrystalline arthropathy (n = 1).
We carried out a prospective study of the clinical and biological features characterizing the acute viremic and post-viremic phases of human Chikungunnya infection in patients referred to the ED for febrile athralgia. The patients without Chikungunya entering the ED with fever and arthralgia during the study were used as a control group. The monthly numbers of newly admitted patients with CHIKV viremia in our study were consistent with the estimated incidence in La Réunion
To our knowledge, this is the first prospective study on the clinical and biological aspects of acute Chikungunya infections in adults with differentiation between the viremic and non-viremic phases during an outbreak. Previously published clinical and biological data were obtained from retrospective analyses, usually in the absence of virological confirmation of acute infection. Several studies have used anti-CHIKV IgM as an acute phase criterion but they are still present in more than 50% of patients a year after the onset of the disease
Moreover, most of these retrospective studies were carried out in countries where co-infections with arboviruses such as Dengue and Yellow-fever viruses are likely to occur
Since 1953, the classical clinical features of acute Chikungunya associate the triad fever, arthralgia and inconstant skin rash
Arthralgia is key to the clinical diagnosis of acute CHIKV infection. However, forms with secondary arthralgia or without arthralgia have been described in Asian studies
The frequency of skin rash ranged from 20% to 85%
Our study illustrates the variety of the other clinical manifestations that can be associated with CHIKV infection. Yet, these symptoms are non-specific as they can be present in a number of other viral infections. Some of these clinical symptoms may also correspond to decompensation of underlying conditions and to iatrogenic effects (e.g. paracetamol and hepatitis, non-steroidal anti-inflammatory and kidney failure).
Severe clinical forms with neurological
Neurological symptoms (vertigo or confusion) observed in our study may be attributable to fever and dehydration. However, a neurotropism of CHIKV has several times been suspected
Mazaud
Cases of severe acute hepatitis occurring during the CHIKV infection have already been described in La Réunion. While it was suggested that this virus may target the liver –a finding confirmed in our animal model in the first hours of infection–, acute hepatitis seems to be mainly promoted by chronic ethylism, denutrition and paracetamol toxicity
When using the two cardinal clinical signs in acute phase, fever and arthralgia, for the diagnosis, we found a specificity of 99,6% and a positive predictive value of 84.6%. Leucopenia and lymphopenia could be used to aid in the diagnosis of CHIKV infection in acute phase, but not for formal diagnosis. The positive predictive values for these parameters, found in our work, are inappropriate. Indeed, the high number of CHIKV-infected patients compared to controls tends to artificially raise the positive predictive values and decrease the negative predictive value. So, leucopenia/lymphopenia values are suggested as only one parameter that could be a part of a diagnosis algorithm. Other mosquito-transmitted viruses with overlapping geographic distributions, specifically Dengue Fever, can have similar hematologic abnormalities. However because of the risk of transmission of the Chikungunya fever in European countries free of Dengue Fever, these hematologic abnormalities are of interest and value.
Factors influencing disease severity are dominated by age and comorbidities. However, these two criteria are strongly linked. Among viremic patients, age under 65 was an excellent predictor of non-severity (severity negative predictive value 85.6%), with only functional impotence due to lower limbs pain and inability to walk leading to hospitalization in this group.
Little is known about the pathophysiology of CHIKV infection, in contrast to better characterized alphaviruses such as Sindbis and Ross River viruses. Sourisseau
The worldwide distribution of