Ecology of leishmaniasis in Southern France. 18. Enzymatic identification of Leishmania infantum Nicolle, 1908, isolated from Phlebotomus ariasi Tonnoir, 1921, spontaneously infected in the Cévennes

Out of 187 female Phlebotomus ariasi caught in the Cévennes focus of leishmaniasis 3 were found naturally infected with Leishmania. The infection in one of the three had spread from the midgut to the pharynx and proboscis. Stocks of Leishmania were isolated from two of the flies and 8 isoenzymes were examined. The newly isolated parasites were found to be indistinguishable from zymodeme 1 of Leishmania infantum s. st.     

Ecology of leishmaniasis in the south of France. -- 12. Horizontal dispersion of Phlebotomus ariasi Tonnoir, 1921. Preliminary experiments (author's transl)

By use of mark-release-recapture methods, evidence was obtained of the distance of the dispersion of Phlebotomus ariasi Tonnoir, 1021. Female flies, collected in a valley in the Cévennes mountains (at Roquedur, Gard), were marked with fluorescnt powders, released an then recaptured by searching with ultra-violet lamps. The majority of the flies recapture were among ones given a blood meal shortly before release. Recaptures were made from the second day after release. A number of females migrated with blood in the midgut; their ovaries were up to and including stage V. The distance between the extreme points of recapture was about 1 km, and the maximum recorded distance between points of release and recapture was 750 m. The epidemiological interest of these observations is that, at least in the Cévennes foci, the sandfly as well as the dog must now be considered as capable spreading the pathogenic agent of visceral leishmaniasis.     

Ecology of leishmaniasis in the south of France. 19. Determination of the hosts of Phlebotomus ariasi Tonnoir, 1921 in the Cévennes by bloodmeal analyses

Engorged sandflies were collected using 58 CDC light traps set up nightly for 5 weeks at 12 stations in the commune of Roquedur, Gard, France, in the Cévennes focus of leishmaniasis. Of 782 engorged females, 593 were Phlebotomus ariasi, 3 were P. mascittii and 186 were not identified. Using the precipitin ring test and counter-current immuno-electrophoresis, the bloodmeals were tested with antisera to man, leporids, rodents, canids, mustelids, equids, suids, bovids, birds, lizards and amphibia. Of 530 identified bloodmeals, 2 were avian blood, 26 were mixed meals of mammalian blood and 25 were meals taken from unidentified mammals. Of the 477 other sandflies, 211 (44.2%) had fed on canids, 107 (22.4%) on man, 70 (14.7%) on bovids (presumed to be cattle at one station and goats elsewhere), 33 (6.9%) on leporids (probably mostly domesticated rabbits), 26 (5.5%) on mustelids (probably badgers), 17 (3.6%) on horses and 13 (2.7%) on rodents (probably brown rat). The proportions of feeds on different mammals varied according to their availability at each station. When both man and dog were equally available, the dog was preferred. The finding that, away from human habitation, P. ariasi commonly feeds on mustelids suggests the need for a reappraisal of animals of this family as possible reservoirs of leishmaniasis in the Cévennes.     

Ecology of leishmaniasis in the south of France. 21. Influence of temperature on the development of Leishmania infantum Nicolle, 1908 in Phlebotomus ariasi Tonnoir, 1921. Experimental study

The influence of temperature on the life-cycle of Leishmania infantum Nicolle, 1908 (isolated from a dog in the Cévennes) in a known vector (Phlebotomus ariasi Tonnoir, 1921) was studied with special reference to the proportion of flies infected and the intensity and localization of parasites in the sandfly. Wild female sandflies were caught at night by active searches and were put with a heavily infected dog in a mosquito net on the night of capture. On the following morning, engorged females were tubed individually and were then maintained at 10, 15, 20, or 25 degrees C (+/- 1.5 degrees). The temperatures were chosen after preliminary experiments which showed that temperatures of 30 degrees C or less than 5 degrees C were lethal to both the sandfly and, usually, the parasite. Midguts of the flies were dissected and examined 6 to 10 days after the infective feed. Although there were no obvious differences in the proportions of infected sandflies at different temperatures, a statistical analysis of the finding (chi 2 test) showed that raising the temperature: significantly increased the overall proportion of infected sandflies; speeded up the multiplication of promastigotes in the midgut; controlled the movement of parasites forwards into the thoracic midgut (from 15 degrees C); encouraged the attachment of the flagellates to the wall of the stomodaeal valve (from 20 degrees C). The use of an exponential model to deduce the size of the parasite population at the different temperatures led to the conclusion that the optimum temperature for L. infantum is in the region of 25 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ecology of leishmaniasis in the south of France. 20. Dispersal of Phlebotomus ariasi Tonnoir, 1921 as a factor in the spread of visceral leishmaniasis in the Cévennes

The dispersal of Phlebotomus ariasi was studied in mark-release-recapture experiments in the summer of 1980 in a valley on the north-eastern slopes of the Oiselette range in the Cévennes mountains, in the commune of Roquedur, Gard, 50 km north of Montpellier, France. More than 5,000 specimens of P. ariasi were marked with fluorescent powders and released in 9 batches at 3 different places. Seven batches were engorged females and two were unengorged females and males. From 1-29 days after release, 497 marked sandflies (approximately 9%) were recaptured by active searches with UV lamps or in 58 CDC light traps set up in groups of 4 or 5 at 12 recapture stations. Females released engorged generally remained within 250 m of the release point for the first eight days while the bloodmeal was being digested after which there was a tendency to disperse to distances greater than 350 m presumably in a search for oviposition sites or another bloodmeal. The furthest distance to which a female released engorged was shown to move was 925 m; it was caught 12 days after release. Some of the females released unfed quickly moved away from release points, sometimes to distances of 1,000 m or more. One of these was caught 68.5 hrs after release at a station 2,200 m from the release point. Male sandflies tended to stay near the point of release and were not recaptured at distances greater than 600 m. There was no evidence that the movement of the sandflies was assisted by wind. Observations on the dispersal of female sandflies confirm that leishmaniasis can be more widely spread than generally assumed by the movements of the vector.     

Ecology of leishmaniasis in the south of France. 11. Canine leishmaniasis: successful experimental transmission from dog to dog by the bite of Phlebotomus ariasi Tonnoir, 1921 (author's transl)

As part of a study of visceral leishmaniasis in the Cévennes in southern France, an infection was transmitted from dog to dog by the bite of a single sandfly, Phlebotomus ariasi Tonnoir, 1921. The role of this species as a vector, suspected from earlier studies, is, therefore, confirmed. Twenty female sandflies, which had engorged on a naturally infected dog 23 +/- 2 days previously were put with a healthy dog which, after an incubation period of 15 months, developed viscero-cutaneous leishmaniasis. In dissections of the sandflies immediately after contact with the experimental dog, it was found that only one had engorged. All of 17 sandflies dissected had midgut infections: 10 of these also had infections in the pharynx. The engorged specimen additionally had parasites in the proboscis, a condition thought by many workers to be necessary for the parasite to be transmitted by bite.     

Cutaneous leishmaniases in French Guiana

Cutaneous leishmaniases are endemic over the entire territory of French Guiana. At least 5 distinct Leishmania species coexist in the sylvatic ecotopes of this French territory. The present paper checks the advances in the ecological research field during the past 5 years. The current epidemiological situation and trends are detailed successively Links between the recrudescence of leishmaniases and gold-mining are highlighted. The potential adaptation of the pathogenic complexes to the newly anthropized habitats is also described.     

Situational analysis of leishmaniases research in Kenya

Leishmania spp are protozoan parasites of the Trypanosomatidae family that cause disease in humans and animals. In general, infections with these parasites can be divided into three main forms namely, cutaneous, mucocutaneous, and visceral leishmaniases. The disease is prevalent in many tropical and subtropical regions of the world, where it is transmitted via the bite of an infected sand fly. Leishmaniasis has been known to be endemic in parts of Kenya from as far back as early in the 20th century. These endemic areas include Turkana, Baringo, Kitui, Machakos, Meru, West Pokot and Elgeyo Marakwet districts which have been reported to be endemic for kala-azar. Recent outbreaks of VL have been reported in the previously non-endemic districts of Wajir and Mandera in North Eastern Kenya between May 2000 and August 2001. The vector for VL in Kenya is Phlebotomus martini though other vectors including P. orientalis have been reported. Baringo district is the only foci reported where both VL and CL are known to occur in Kenya. The aetiological agents for CL which include L. major which has been reported in Baringo; L. tropica in Laikipia, Samburu, Isiolo, Nakuru and Nyandarua districts while L. aethiopica has been reported in the Mt Elgon area. In Kenya, P. duboscqi, P. guggisbergi have been shown to be the vectors of L. major and L. tropica, respectively, while P. pediffer, P. longipes and P. elgonensis have been implicated as vectors of L. aethiopica. Since 1980, the Kenya Medical Research Institute (KEMRI) has spearheaded research on leishmaniases research in Kenya focusing on various aspects including characterization of Leishmania species, biology, and ecology of sand fly vectors, development of biological strategies for sand fly control, identification of animal reservoirs, diagnosis, new treatment strategies, new chemotherapeutic agents, and vaccine-related studies. KEMRI, a founding partner of the Drugs for Neglected Disease Initiative (DNDi), whose overall aim is to address lack of new or improved drugs for neglected diseases (which include leishmaniases, malaria, trypanosomiasis and Chagas disease) has made major contributions in leishmaniases research and control in Kenya and the eastern Africa region.     

Presence of Phlebotomus bergeroti, Phlebotomus chabaudi, Phlebotomus chadlii and Sergentomyia christophersi in Morocco]

The authors indicate the presence at Morocco of the four following sandflies: Phlebotomus bergeroti Parrot, 1934, Phlebotomus chabaudi Croset, Abonnenc et Rioux, 1970, Phlebotomus chadlii Rioux, Juminer et Gibily, 1966 and Sergentomyia christophersi (Sinton, 1927). Among them, Phlebotomus bergeroti, an element of eremitic affinity, is found at the north of the Atlas under a sub-humide bioclimat.