[Leishmaniasis in Ecuador. 1. Incidence of cutaneous leishmaniasis on the Pacific coast]. / Leishmaniose en Equateur. 1. Incidence de la leishmaniose tégumentaire sur la façade pacifique.

A clinico-epidemiologic survey on cutaneous leishmaniasis, due to Leishmania panamensis, was carried out on 961 persons in two study areas of the Pacific coast of Ecuador, to estimate the prevalence and the incidence of the disease. In the preandean hills, at Paraiso Escondido, the prevalence of active lesions was 4.8%; in the hills of the coastal cordillera, at La Tablada, it was 3.6%. The incidence of new cases in 1991 was high: 147% in the first village, and 106% in the second. These data are far higher than the Health Ministry statistics. The cumulated prevalence, obtained by addition of the scars and active lesions of leishmaniasis, was as high as 66% at Paraiso Escondido, and 47% at La Tablada. Most of the patients (62%) had only one ulcer or scar. Most of the people are contaminated during the first five years they live in these endemic areas. Nevertheless, the incidence remains high in all the age groups, because large numbers of migrants coming from non endemic regions are continuously settling in these colonization areas. Interviews have shown that the contaminations had occurred in the dry season, between July and December. These findings were confirmed by passive case detection at the Hospital A. Egas of Santo Domingo which covered the region. Contamination of young children and position of the lesions on the face suggested a domiciliary transmission, like in Panama and on the Pacific coast of Colombia.

[Leishmaniasis in Ecuador. 3. Lutzomyia trapidoi, vector of Leishmania panamensis]. / Leishmaniose en Equateur. 3. Lutzomyia trapidoi, vecteur de Leishmania panamensis.

Lutzomyia trapidoi, the more abundant anthropophilic species, is a presumed leishmaniasis vector in the Pacific foothills of Ecuador. Three biotopes have been sampled (dwelling, and nearby coffee crop and primary forest) in the focus of Paraiso Escondido, by human bait catches, from August 1991 to October 1992. A large number of sandflies, 6,965 specimens, have been dissected to estimate peri and hypopyloric infections. All the peripyloric infections, characterized by isoenzyme electrophoresis, were Leishmania panamensis. The percentage of these infections was low, around 3%, but they were massive. They occurred only in dry season. Hypopyloric infections were observed in Lu. trapidoi all the year round in the three biotopes. Their percentage was high, reaching 40%. Despite of many trials to cultivate the parasite on NNN medium, no stain could be isolated. It is suggested that the parasite could be L. equatorensis.

[Leishmaniasis in Ecuador. 5. Leishmaniasis and anthropization on the Pacific coast]. / Leishmanoise en Equateur. 5. Leishmaniose et anthropisation sur la façade pacifique.

We have evaluated the impact of anthropization of the forest on the incidence of leishmaniasis, due to Leishmania panamensis, in three coastal study areas, Corriente Grande (primary forest), Paraiso Escondido and La Tablada (secondary forest). The situation of isolated dwellings, in deforested areas, has also been analysed in the last two stations. In each station, the study of the density of anthropophilic sand flies, specially Lutzomyia trapidoi, has been conducted in the domestic environment, coffee plantations and undergrowth. The incidence of leishmaniasis was nearly non existent in primary forest, though it ranged from 106 to 147% in the more or less cleared forest. At Corriente Grande, none Lu. trapidoi was caught in houses. In the undergrowth, catches were low (8% of the total). At Paraiso Escondido, Lu. trapidoi was the dominant species, with more than 83% of the catches in the undergrowth and in the coffee plantations (41 Man/hour), as well as in dwellings (10.6 M/h). At La Tablada, in the domestic environment, Lu. gomezi, was the dominant species: 2.8 M/h against 0.1 M/h for Lu. trapidoi. In the coffee plantations and in the undergrowth Lu. trapidoi was the main species, 21 M/h and 14 M/h. Thus in the primary rainforest, leishmaniasis transmission can be very low. In disturbed forest, coffee plantations near houses are good biotopes for Lu. trapidoi. The cycle of L. panamensis has been adapted to this new ecological situation, by being closer to the houses. The reservoirs live and circulate throughout coffee plantations. In deforested areas, neither aggressive sand flies have been observed, nor leishmaniasis transmission.

[Leishmaniasis in Ecuador. 6. Epidemiological and entomological note on the focus of leishmaniasis in Zumba]. / Leishmaniose en Equateur. 6. Note épidémiologique et entomologique sur le foyer de leishmaniose de Zumba.

The Zumba focus of tegumentary leishmaniasis lies in the southwards Amazonian region of Ecuador. A clinico-epidemiological study has been carried out in the area on 83 patients attending health centers. All the biotopes suitable for sandflies, including dwellings, have been sampled from February to September 1992 by light trap and human bait catches. The number of sandflies caught amounts to 2,547. Anthropophilic sandfly fauna is poor and only three species have been recorded. Lutzomyia serrana abounds inside dwellings where it bites men even during daytime. The parasite was identified as an intermediate form between Leishmania panamensis and L. braziliensis. It will be described elsewhere. The high proportion of facial lesions suggests a domiciliary transmission for which Lu. serrana could be a good vector candidate.

[Introduction of onchocerciasis in Central America: the role of the French expeditionary corps to Mexico (1861-1867)]. / L'introduction de l'onchocercose en Amérique centrale: le rôle du corps expéditionnaire français au Mexique (1861-1867).

Close relationships between American and African strains (from savanna) of onchocerciasis have been confirmed by biochemical analysis. It is admitted that the parasite could have been introduced by slave trade. But in Mexico, Torroela supported the hypothesis that onchocerciasis was introduced by Nubian soldiers of the French troops between 1861 and 1867. Some of the 600 soldiers of the Egyptian bataillon, included in the French expeditionnary corps, could have been onchocerciasis carriers. But these troops caserned in Vera Cruz remained in the littoral plain and have not been in contact with the Oxoaca focus of onchocerciasis. It is very unlikely that they can have been at the origin of the disease focus.

Transmission factors in malaria epidemiology and control in Africa.

Genetic and environmental components of factors contributing in malaria transmission are reviewed. Particular attention is given to density dependent regulation of vector populations in relation to the survival rate of anophelines. The expectation of vector control activities are different according to the epidemiological characteristics of malaria, mainly its stability. In areas with perennial and high transmission (stable malaria) vector control could reduce malaria related morbidity and mortality, without any effect on the endemicity. However this need further investigations. In areas where the transmission period is very short (unstable malaria), vector control will have an important impact on the disease and on the endemicity. Control projects using indoor spraying with insecticide and impregnated bed nets are discussed.

Transmission factors in malaria epidemiology and control in Africa

Genetic and environmental components of factors contributing in malaria transmission are reviewed. Particular attention is given to density dependent regulation of vector populations in relation to the survival rate anophelines. The expectation of vector activities are different according to the epidemiological characteristics of malaria, mainly its stability. In areas with perennial and high transmission (stable malaria) vector control could reduce malaria related morbidity and mortality, whithout any effect on the endemicity. However this need further investigations. In areas where the transmission period is very short (unstable malaria), vector control will have an important impact on the disease and the endemicity. Control projects using indoor spraying with insecticide and impregnated bed nets are discussed

[Epidemiology of cutaneous leishmaniasis in Bolivia. 1. Description of study zone and prevalence of the disease]. / Epidémiologie de la leishmaniose tégumentaire en Bolivie. 1. Description des zones d'étude et fréquence de la maladie.

An epidemiological survey of tegumentary leishmaniasis (Leishmania (Viannia) braziliensis) was carried out in three regions of Bolivia in the Andean foothill and Amazonian forest. It was based on the record of lesions and scars on all the inhabitants of selected representative villages. In the Yungas, an area cultivated from the XVIIth century, males and females are equally infested, mostly before they were 10 years old (65%); 48% of scars were on the head. In Alto Beni and Pando, areas covered with primary rain forest, males are significantly more affected than females. The majority of scars were on the legs. The males of the three areas were equally affected. These results suggest that: --in the Yungas, contamination takes place among children in villages during the night; --in the Alto Beni and in the Pando, the infection rate is linked to the professional activities of adults, and men are more at risk than women. Only 7% of the lesions are evolving in grave forms of mucocutaneous ulcers. These forms represent the main load of the disease from the public health point of view. It has been found heavier in the Yungas (1.32%) and in the Alto Beni (1.14%) than in the Pando (0.21%). It should be noted that the first infection can give raise to several lesions. But reinfections are rare, which supports the view that the first infection is protective against the following ones.

[Epidemiology of cutaneous leishmaniasis in Bolivia. 2. Transmission patterns]. / Epidémiologie de la leishmaniose tégumentaire en Bolivie. 2. Modalités de la transmission.

In Bolivia the transmission of tegumentary leishmaniasis due to Leishmania (V.) braziliensis depends both on environmental factors and human activities. In the Yungas, transmission takes place in the houses during the night. The vector is Lutzomyia nuneztovari anglesi Le Pont & Desjeux, which enters the houses after 10 p.m. and leaves them before 6 a.m. This transmission pattern explains why men and women are equally infected, generally before 10 years old. Some more adults are infected very likely in coffee plantations or in the relict forest where the same vector species abounds and bites in daytime. In the Alto Beni, pioneers, mainly males, are infected when clearing the forest. Three Psychodopygus species have been shown to be the vectors. The risk is drastically decreasing when people establish in plantations or nearby villages because sandfly vectors do not get easily out of the forest cover. In the Pando, forest people are infected when harvesting Brazil-nuts or bleeding the rubber-trees, the two main activities in the area. It is very likely that Ps. c. carrerai is one of the vectors. Pando and Alto Beni primary rain-forests are natural primary foci of Le. braziliensis. So far the mammalian reservoirs are unknown but the circulation of the parasite has been proven by the fast contamination of receptive people entering the forest. The Yungas primary forest may be also considered as a relict focus. The cultivated area of the Yungas is an anthropic secondary focus. The vector Lu. n. anglesi became adapted to coffee plantations from which it enters the houses and transmits the parasite to man.

[Impact of the spraying of deltamethrin in a focus of leishmaniasis in Bolivia]. / Impact de pulvérisations de deltaméthrine dans un foyer de leishmaniose de Bolivie.

After one month of entomological observations to record pretreatment data, a sub Andean village of Yungas, Bolivia (alt. 1500 m) was sprayed at the beginning of the rainy season (January 1987). Houses were treated inside and outside with deltamethrin at 0.025 g/sq.m.; kennels, hen-houses and stacks of adobe were also sprayed in the same way. As a result of the treatment, Lutzomyia longipalpis, the local vector of visceral leishmaniasis, disappeared from houses and animal shelters for 9 and 10 months respectively. The impact of the treatment on the populations of Lu. nuneztovari and anglesi, the presumed vector of tegumentary leishmaniasis, was not obvious. As compared with pretreatment data, the rate of engorged females in houses decreased by two, and their density was also reduced. But these data are difficult to interpret due to the natural seasonal variation in density in this species. Moreover, the information from the control village did not correspond as expected. Lu. n. anglesi is a highly exophilic species in this area, a behaviour which could explain the limited impact of the treatment on this sandfly.

[Leishmaniasis in Bolivia. IV. The dog in the cycles of leishmaniasis in Bolivia]. / Leishmaniose en Bolivie. IV. Le chien dans les cycles des leishmanioses en Bolivie.

In Bolivia, the dog is involved in the cycle of visceral leishmaniasis (Leishmania (Le.) chagasi) in the Yungas (alt. 1,000-2,000 m), and also in the cycle of cutaneous leishmaniasis (Le. (V.) braziliensis) in the Alto Beni (alt. 400-600 m). But it plays a different role in the two cycles. In the Yungas focus, it is the main reservoir of Le. (Le.) chagasi and the source of contamination for man. In the Alto Beni focus, it is only a "victim-host", like man, of Le. (V.) braziliensis; the reservoir of which is unknown. Wild mammals are very likely to be involved.

[Malaria in Guiana. I. General status of the endemic]. / Le paludisme en Guyane. I. Situation générale de l'endémie.

Before 1949 malaria was highly prevalent in the whole territory of French Guiana. When malaria control based on house-spraying and drug prophylaxis was implemented in 1950 the disease sharply dropped below 20 cases per year. Since 1976 despite vector control malaria is rising again. In 1987, 3,269 cases have been notified giving an incidence of 37.6 per thousand for the whole country population; only four deaths were recorded. All the age groups were concerned but the transmission was restricted to some foci along the Oyapock river (prevalence rate 25%), along the Maroni river (prevalence 2.3%) and in a few places of the coastal area. The main cities remain malaria free. In vivo resistance to chloroquine was observed in 22% of the cases which could be cleared by amodiaquine or quinine.

[Malaria in Guiana. II. The characteristics of different foci and antimalarial control]. / Le paludisme en Guyane. II. Les caractéristiques des différents foyers et la lutte antipaludique.

In French Guiana, the distribution of malaria in foci inhabited by quite different ethnic groups calls for specific studies. Along the Oyapock on the Brasilian border and along the Litani on the Surinam border, incidence among American Indians and Creoles ranges from 300 and 900 per thousand; Plasmodium falciparum accounts for 65% and P. vivax for 35%. Along the middle and lower Maroni on the Surinam border, the Boni and Ndjukas Negroes move freely through the frontier and since the civil strife Surinamese used to attend health centres of Guiana. Therefore it is difficult to find the sources of contamination and the incidence among French citizens; P. falciparum is the only parasite recorded in this focus. In 1987 a small outbreak mainly due to P. vivax, occurred in a Lao refugees village in the hinterland. The coastal foci harbour large communities of Haitian and Brazilian migrants. The vector is Anopheles darlingi and up to now there is no evidence that other species could be involved. The rise of malaria despite of control measures involves several factors: the house spraying is no more accepted by a large percentage of house holders and the alternative larviciding has only a limited efficacy; the houses of American Indians have no walls to be sprayed; there is a continuous introduction of parasites by migrants. It has been said that vectors have change their behaviour toward exophily but such a statement has not yet been supported by evidence. All these factors should be taken in account to improve malaria control.

[Arbovirus diseases in South America and Caribbean Islands (author's transl)]. / Arboviroses en Amérique du sud et dans les Caraibes.

Historically, yellow fever has dominated arboviral diseases in South America and the Caribbean and sylvatic cases still occur every year (more than 200 in 1979). The dengue, by the very large number of cases occurring in the area during successive epidemics--the most important being the last one in 1977-1978--is a serious problem for public health, an epidemic of hemorrhagic dengue being a constant threat. Encephalitides are the third syndrome of arboviral etiology observed in the South American subcontinent. Some which preferably attack horses have been known for a long time whereas the one due to the Rocio virus of an even graver prognosis, was recently discovered. These diseases present a large range of epidemiological forms. Dengue is an example of an urban illness transmitted from man to man through the mosquito, Aedes aegypti. But most of the viruses circulate between vectors and wild vertebrates in sylvatic cycle. For some viruses, both mechanisms can be involved. It is the case for Oropouche virus and yellow fever even if at present the urban form is the only recorded for the latter.