CONTRIBUTION TO LEPTOSPIROSIS SURVEILLANCE IN FRANCE IN 2003
INTRODUCTION
In 2003, 6074 serological and 104 bacteriological analyses have been performed at the National Reference Center for diagnosis of leptospirosis.
The total number of recorded cases is 671 (close to the 2002 653 cases). 319 of them (including 5 cases detected by PCR only and 2 bacteriological cases) were observed in continental France (Table 1)
.The incidence rate in continental France has been 0.55/100000h in 2003, which, taking in account the heat wave during summer, is rather reasonable (Table 2).
In overseas areas, in opposition to what is usual, the "Departements" are characerized by more cases than the "Territories": the maximum is reach in Guadeloupe (incidence 33.1) (Table 3) then in Martinique (20.4) (Table 4), La Reunion (11.9) (Table 5) and French Guyana (10.2) (Table 6)
.Table 8), the incidence is rather low: French Polynesia (6.9) (Table 7) and New Caledonia (9.5).
EPIDEMIOLOGICAL TRENDS AND SURVEILLANCE
Three distinct cases definitions are used according to the considered area. The aim is to not take into account the residual low titers in serology, the frequency of which is quite different from an area to another one.
*1) In New Caledonia, the incidence is so high (often > 100/100000) that, if considered, the prevalence of residual low titers would lead to overestimation of the disease. Confirmed cases are defined as bacteriologically or PCR confirmed ones and/or seroconverted patients (four fold increase in titer). Probable cases correspond to 2).
*2) In high endemicity area (usually < 50/100000) such as La Reunion and French Polynesia, a so-called "clinical" cut off (1/400 or more in Micro Agglutination Test: MAT against any of the pathogenic antigens) is used in order to prevent overestimation due to residual titers.
*3) In low endemicity areas, a so-called "epidemiological" cut off of 1/100 is considered. Indeed the low residual titers prevalence is unsignificant and, in opposition, if used, the 1/400 cut off would lead to underestimation of many cases due to the chronologically non-optimal sampling. It would also be the case for early treated leptospiroses or those due to Grippotyphosa serogroups (often characterized by low titers). This definition is used in French West Indies, French Guyana and continental France. In these conditions, the case definition is a compromise between (serological) prevalence and incidence rates.
The number of serological cases in continental France in 2003 (311) (Table 1) is slightly superior to the mean of the five last years (297)(Fig 1) (data restricted to those from CNR itself) due to an alert unopportunately published in newspapers at the end of August.
. The maximum is during August (56) and September (67) but the seasonal distribution is atypical with an unusually high number of cases in the first semester 2003 (114) in the continuation of the 2002 winter. In opposition, the 2003 4th trimester is rather low: 50 cases (Table 1).It is noticeable that the number of serological analyses requests particularly increased in September (
Fig 2) (data restricted to those from CNR itself) due to an alert unopportunately published in newspapers at the end of August.On the geographical point of view (
Table 2), the distribution of cases is again unusual: some usual foci such as Aquitaine or Champagne-Ardennes exhibit the expected high incidence rates, other have usual rates: Poitou-Charentes, Limousin and Basse Normandie although Franche Comte, Pays de Loire and Rhone Alpes exhibit rates under the mean.A more careful study at the "departement" (
Table 9) level shows that in 2003, Dordogne reach an incidence rate of 4.6, higher than the Ardennes' one (2.4) which usually is the highest of continental France. Conversely, "departements" usually among the top ten: Doubs, Sarthe, Loire Atlantique or Vendee have rather low incidence rates in 2003.The conclusion for continental France in 2003 which has been characterized by an exceptional heat wave is that french people swimmed a lot (increasing of 73% between 2002 and 2003 of deaths due to swimming) but in waters rather less infected by Leptospira than they usually are (with the exception of Ardennes and overall Aquitaine) (
Table 2).Concerning French overseas Territories, the climate cooler than usual (in spite of the occurrence of a hurricane) in Nouvelle Caledonie and the lack of access to a local diagnosis in Polynesia (
Table 7) both explain the numbers of cases exceptionally low in the Pacific area, in New Caledonia (19 cases: 11 confirmed and 8 probable) as well as in French Polynesia (Table 7).Conversely, in overseas french "departements", in La Reunion (
Table 5), the climate has been warm and humid (heavy rains) leading to numerous cases as those previously recorded in the nineties. In French West Indies, La Martinique (Table 4) exhibits an usual number of cases as well as Mayotte (Table 8) in the Indian Ocean (Table 8) although La Guadeloupe (Table 3) and French Guyana (Table 6) records unexpected numbers: respectively 140 and 16. In Guadeloupe, a more active surveillance due to an active sensibilisation of the physicians probably lead to more serologies requests. Additionally, the climate (heavy rains almost all over the year in 2003) explains the high number of cases and its distribution more homogeneous than usual.PUBLICATIONS CONCERNING LEPTOSPIRES (RESEARCH AND EXPERTISE)
IN PUBLICATIONS FROM THE WHOLE UNIT
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Publications 2003 of the unit on Pasteur's references database |
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Unique physiological and pathogenic features of Leptospira interrogans revealed by whole-genome sequencing. 
Inhibition by eicosapentaenoic acid of IL-1beta-induced
PGHS-2 expression in human microvascular endothelial cells: involvement of
lipoxygenase-derived metabolites and p38 MAPK pathway.
Construction and complementation of the first auxotrophic
mutant in the spirochaete Leptospira meyeri.
Toll-like receptor-mediated tumor necrosis factor and
interleukin-10 production differ during systemic inflammation.
Leptospira spp. possess a complete haem biosynthetic pathway
and are able to use exogenous haem sources.
Genetic evidence for the existence of two pathways for the
biosynthesis of methionine in the Leptospira spp.
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