Chippaux, Jean-Philippe

Theakston, R.D.G.

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Annals ofTropical Medicine and Parasitology, Vol. 81, No. 3,301-304 (1987)c~te. I 5 ~ 
Epidemiological studies of snake bite in French Guiana 
BY J. P, CHIPPAUX AND R. D. G. THEAKSTON 
Centre ORSTOM de Cayenne, French Guiana and Liverpool School Tropical Medicine, Liverpool, U.K. 
Received 6 November I985 
,. 
1.1 
The incidence of snake bite and the presence of venom antibody in previous snake bite victims was 
investigated in French Guiana. Theincidence proved to be highest (SOO/lOO 000) ininhabitants ofbush 
regions and lowest (45/100 000) in urban areas. Of43 sera tested for specific venom antibody 22 (51 %) 
were positive, and most of these individuals~suffered severe or moderate poisoning. The main species 
involved, as assessed by detection ofvenom antibody by ELISA, were Lachesis mula, Bothrops bra& B. 
bilineatus and B. atrox. The significance of these findings is discussed. 
Epidemiological data concerning the incidence of snake bite in South America are rare. To 
rectify the situation an attempt has been made to evaluate snake bite morbidity in French 
Guiana, using survey techniques combined with enzyme-linked immunosorbent assay 
(ELISA). The population comprises approximately 73 O00 inhabitants within an area of 
90 O00 km2 and is unevenly distributed in the study region; 93% inhabit the coastal area and 
less than 10% are involved with agriculture. Primary forest covers 95% of the territory and is 
inhabited by less than 5000 people. The population can be divided into three major groups 
consisting of (1) urban inhabitants (62 000) without any contact with primary forest areas; (2) 
villagers (7000) with minimal contact with forest regions; (3) inhabitants of bush regions 
(4000). The latter population constitutes the major group at risk from snake bite. 
The major ethnic groups are CTeoles, expatriate French, Indians, and various immigrant 
groups (e.g. Brazilians, Asians, West Indians and others). 
MATERIALS AND METHODS 
Seventeen localities were studied covering 97% of the total population of the territory. A 
retrospective study was made in all regions using details obtained from hospital records. A 
second prospective study was carried out in all localities using a standard questionnaire 
(recording name, age, sex, habitation, ethnic group, circumstances of bite, location of bite and 
clinical and therapeutic data) between January 1982 and May 1983. Finally, a detailed study 
was performed in four villages in which each inhabitant was asked to provide details of 
previous bites. Results obtained using the three methods were combined. 
An attempt was made to trace all individuals who either reported previous bites during the 
surveys or who were mentioned in hospital records. Only previous snake bite victims on whom 
adequate clinical data were available, or those bitten during the prospective survey, were 
considered. Only previous victims who had had definite clinical symptoms of envenoming 
were invited to donate blood samples for venom antibody determination. The samples were 
collected at periods ranging from one month to 35 years after the bite. Fifty microlitres (50 pl) 
ofwhole blood were collected by finger-prick into capillary tubes, the contents ofwhich were 
immediately expelled onto Whatman No. 1 filter paper, allowed to dry and stored in sealed 
polythene bags at room temperature. Samples were mailed to Liverpool and subsequently 
assayed using ELISA. Blood was eluted from the filter paper using PBS-Tween, pH 7.4 
(Theakston et al., 1981a) to a final dilution of 1/50. Each sample was then assayed in duplicate 
as described by Theakston et al. (1977). Because of difficulties in obtaining negative control 
0003-4983/87/030301 +O4 $03.00/0 O 1987 Liverpool School ofTropical Medicine 
302 SNAKE BITE IN FRENCH GUIANA 
samples from individuals in the same area, controls comprised 15 samples from Ecuadorians 
not previously exposed to snake bite. These were assayed simultaneously with the test samples 
and the mean control optical densities were subtracted. 
(Village) 
Inhabitants 
of bush 
areas 
RESULTS 
Details of the epidemiological findings have been published elsewhere (Chippaux et al., 1984). 
Of 210 previou, snake bite cases detected during the study period only 137 were witable 
because of loss o hospital records; 66 victims were not sampled because the records indicated 
few or no symptoms of envenoming, but 71 individuals exhibited clear clinical symptoms of 
envenomation a recorded by hospital staff. 
Only 43 out f the 7 1 individuals volunteered to donate a blood sample (none in the town 
group, 20 in th village group and 23 in the bush region group: Table 1); the remainder 
refused. All 43 victims had presented with at least minimum local symptoms (e.g. pain, 
sw'elling) suggesting viper bite poisoning. Eight previous victims suffered moderate paisoning, 
as defined by ither local bleeding and/or local necrosis, and 13 had severe poisoning 
TABLE 1 
snake bite victims 
Population distribution, incidence of snake bite, and venom antibody assay results in 43previous' 
* comprising mor 1 generalized haemorrhage and local necrosis (Table 2). 
3 3 
2 1 
Indians 1500 150 
Others 1500 
Creole 1000 2 1 
Indians 1000 600 17 9 
Others 20001 4 2 
Geographical Ethnic Incidence[ No. of sera No. of sera 
group group Population 100 O00 collected positive 
Number of samples 
TABLE 2 
positive for venom antibod3, at daferent times following envenoming in relation to the 
Severe viperine Moderate viperine M i l d  viperine 
poisoning poisoning poisoning (swelling) 
T ime from 
bite (years) No. sera No. positive Na. sera fio. positive fio. sera No.positive 
<5  9 7 4 3 9 3 
5-1 5 2 2 3 3 12 4 
> 15 2 O 1 O 1 O 
Total 13 9 8 6 22 7 
The overa 1 incidence off venom antibody is approximately 50:/, (22 out of 43 victims had 
ELISA-positi e samples). The incidence did not appear to be aEeeccted by either ethnic or 
ecological factors (Table 1). Antib'odies against Lachesis muta venom were detected in 15 
victims (five reoles, eight Indians and two others), against Bothrops brazilivenomin three (one 
Creole and t o Indians), against B. bilineatus venom in two (one Indian and one Laotian I 
CHIPPAUX AND THEAKSTON 303 
refugee), and against B. atrox venom in two (one Creole and one Indian). Occasional slight 
cross reactions were detected between different species of Bothrops, and in these cases the 
highest antibody titre was considered to reflect the biting species. 
DISCUSSION 
These findings are in agreement with recent publications. The extent of ELISA venom anti- 
body positives in individuals claiming previous snake bite experience changes from area to 
area. Positivity was 35% in a survey carried out in Nigeria (Pugh and Theakston, 1980) and 
78% in Waorani indians of eastern Ecuador (Theakston et al., 1981b). Differences can be 
explained by variation in ecological situations and epidemiological methods. South American 
Indians certainly appear to be frequently exposed to snake bite, and this is confirmed by a 
higher snake bite incidence and mortality rate than so far recorded in any other population 
studied. 
The method of selection of individuals used in this study probably results in a better 
response in the ELISA test, although it is not quite as subjective as methods used previously 
(Theakston et al., 198 1 a). We consider that in this survey all subjects tested had suffered mild to 
records in which accurate clinical symptoms had been reported. The degree ofpositivity of the 
ELISA and the intensity of the response is influenced by the amount of venom introduced at 
the time of the bite and the time from bite to sample collection. Up to 15 years after the bite 
well-documented victims who suffered severe to moderate systemic poisoning by vipers 
showed an 83% (15/18) positive venom antibody reaction in the ELISA test. I n  mild poison- 
ing seven out of 22 (32%) of victims had detectable venom antibody. In  this survey no 
antibody was discernible at periods greater than 15 years after envenomation. Elsewhere, 
Theakston et al. (1981~) and Pugh et al. (1980) have reported the occasional persistence of 
venom antibody up to 40 years after systemic envenoming. 
Only about 10% of envenomed individuals show a specific response to B. atrox antigens, 
which is surprising as this is the most common venomous species found in the study area 
(Chippaux, 1987). Bothrops brazili and B. bilineatus, which are relatively difficult to find in the 
study area, accounted for about 20% of the positives on the ELISA (10% each), and this figure 
appears to be a genuine reflection oftheir frequency. Finally, L. muta constitutes almost 70% of 
the positive responses, and this species represents less than 10% of the venomous snakes 
collected. In  an earlier study (Chippaux and Bressy, 1981) a method was proposed for the 
evaluation of species of medical-importance to man in the region; during the prospective study 
all snakes encountered in the work area were collected, and it was shown that the number of 
different species collected appears to be related to the species responsible for bites. In French 
Guiana the two methods (ELISA and snake collection) show a wide variation, which may be 
explained by the following hypotheses. First, snake collection may be selective in that some 
species (e.g. L. muta) may be more difficult to catch, possibly because of the temerity or size of 
the individual species. Second, snake collection may be reliable in terms of bites but not in 
terms of actually causing envenomation. For example, B. atrox may be less aggressive than, or 
may not inject venom as frequently as, other species such as L. muta. 
ACKNOWLEDGEMENTS. We thank Dr. J. Galtier and Dr. J. F. Lefait for their technical help in 
the field survey, Dr. Y .  Robin for his encouragements during the epidemiological study and 
Mrs. J. Friend for laboratory assistance. 
i 
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J severe poisoning by venomous snakes, as the selection of individuals was based on medical 
$ 
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REFERENCES 
CHIPPAUX, J. P. (1987). Les serpents de la Guyane française. Faune Tropicale, No. 27.ORSTOM;Paris. 
CHIPPAUX, J. P. & BRESSY, G. (1981). L'endemie ophidienne des plantations de Cote D'Ivoire. Bulletin de la Sociifide 
Pathologie Exotique, 74,458467. 
304 SNAKE BITE IN FRENCH GUIANA 
CHIPPAUX, J. P., GALTIER, J. & LEFAIT, J. F. (1984). Epidemiologie des envenimations en Guyane francaise. Bulletin de 
la Socit2i de Pathologie Exotique, 77,206-2 15. 
PUGH, R. N. H. & THEAKSTON, R. D. G. (1980). The incidence and mortality ofsnake bite in savanna Nigeria. Lancet, 
ii, 1181-1183. 
PUGH, R. N. H., THEAKSTON, R. D. G., REID, H. A. & BAHR, I. S. (1980). Malufashi Endemic Diseases Research 
Project XIII. Epidemiology ofhuman encounters with the spitting cobra, Na@ nigricollis, in the Malumfashi area of 
northern Nigeria. Annals of Tropical Medicine and Parasitolou, 74,523-530. 
THEAKSTON, R. D. G., LLOYD-JONES, M. J. & REID, H. A. (1977). Micro-ELISA for detecting and assaying snake 
venom and venom antibody. Lancet, ii, 639-641. 
THEAKSTON, R. D. G., PUGH, R. N. H. & REID, H. A. (1981~). Enzyme-linked immunosorbent assay of venom- 
antibodies in human victims ofsnake bite. Journal of Tropical Medicine and Hygiene, 84,109-U 12. 
THEAKSTON, R. D. G., REID, H. A., LARRICK, J. W., KAPLAN, J. & YosT,J. A. (19816). Snake venom antibodies in 
Ecuadorian Indians. Journal of Tropical Medicine and Hygiene, 84, 199-202. 
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