CONTRIBUTION
TO LEPTOSPIROSIS SURVEILLANCE IN FRANCE IN 2004
Introduction
In 2004, the CNR received 5967 serological and 76 bacteriological
analyses.
The total number of recorded leptospirosis cases is 679 (close to the
671 cases observed in 2003. Among them,
only 236 (including 7 PCR alone and 1 culture alone diagnosed cases)
have been recorded in continental France (Table 1).
As in 2003 although in opposition to what is usually noticed, more
cases have been in recorded in DOMs (overseas « departments
») than in TOMs (overseas territories). The highest serological
incidence rate is observed inFrench West Indies : Guadeloupe (41.2) (Table 3),
Martinique (18.9) (Table 4), then in Indian Ocean : La Reunion (9.2)
(Table 5) and
finally South America : Guyane (3.8) (Table 6). Concerning TOMs, in 2004 as in 2003, the
incidence is unusuallly low : Mayotte in Indian Ocean (12.2) (Table 7) and in
Pacific Ocean : New Caledonia (6.1) (Table 8) and Tahiti (6) (Table 9).
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.
In French West Indies, we used this definition N°3. However the
analyses recently dramatically increased (for instance they increased
from 233 in 2003 to 571 in 2004). In these conditions, the
spectrum of demands for analyses has been enlarging. In this less
precisely targetted context, serological scares were increasingly
detected : Guadeloupe 2004 : 183 cases with definition one and 121 with
definition 2 (Table 3), and Martinique respectively 72 and 33 (Table 4). We
decided to use in the future the definition 2 for French West Indies.
The number of cases in 2004 in Continental France (236 serological
and/or bacteriological cases) (Table 1) is lower to the mean nuber of the last five years
(300). Such a low number has not been recorded since 1992. The
decreasing trend is dispatched on the whole year. The maximum is
observed in september (44 cases) and October (34 cases) (Table 1).
On the geographical point of view (continental France), the 2004
decreasing incidence is general (0.38 instead of 0.5 last years) (Table 2). It is
observed as well in high incidence areas (only 2 of them are over
1/100000 : Basse Normandie :1.2 and Poitou Charentes: 1.16)
(Table 2), than in normal incidence areas. Only low incidence
areas such as PACA, Picardie or Languedoc Roussillon, kept their
usual rates which in contrast to others, in 2004 seem higher.
When considering the "departments" in continental France (Table 10) (Fig
1), contrasts are sharper. Five reach
or even are over 10 cases, but if for 3 of them it is usual: Nord,
Paris and Ardennes with incidence rates respectively of 0.6, 0.7 and
3.4, concerning Seine Maritime and Calvados they do increase their
usual incidence rates: respectively 0.93 and 1.54 in 2004.
On the whole, in the 2 Normandie regions, has been observed a
recrudescence of Grippotyphosa cases in autumn. It also the cas for Poitou Charentes. (Table 1) (Table 2).
Concerning TOMs, in New Caledonia (Table 8), as in 2003
the climate dry and cool and in Tahiti (Table 7) the lack of local access
to leptospirosis biological confirmation could explain the low number
of cases recorde in the French Territories of the Pacific Ocean (Table 2).
Concerning DOMs, the French West Indies and mainly Guadeloupe recorded
very high numbers of cases. This could be due to a quite rainy year.
For instance in may in Guadeloupe, heavy rains have fallen ten days
long.
Publications in 2004 concerning Leptospira
(research and CNR)
A methylated phosphate group and four amide-linked acyl
chains in
Leptospira interrogans lipid A - The membrane anchor of an unusual
lipopolysaccharide that activates TLR2 - Authors :
Que-Gewirth, NLS, Ribeiro, AA, Kalb, SR, Cotter, RJ, Bulach, DM, Adler,
B, Saint Girons, I, Werts, C, Raetz, CRH
- Source :
Journal of Biological Chemistry. 279(24):25420-25429, 2004
- Risk factors for leptospirosis in metropolitan France:
Results of a
national case-control study, 1999-2000
- Authors :
Nardone, A, Capek, I, Baranton, G, Campese, C, Postic, D, Vaillant, R,
Lienard, M, Desenclos, JC
- Source :
Clinical Infectious Diseases. 39(5):751-753, 2004