[Phlebotomine sandflies (Diptera: Psychodidae) of French Guiana. I--Description of the male of Lutzomyia (Trichopygomyia) depaquiti n. sp]. / Les phlébotomes (Diptera: Psychodidae) de la Guyane française. I--Description du mâle de Lutzomyia (Trichopygomyia) depaquiti n. sp.

Description of a new tropical species of French Guiana: Lutzomyia (Trichopygomyia) depaquiti. The principal character is the aedeagus morphology that presents lateral expansions like a marine anchor. An other particularity is centered on the complex paramere with a lateral lobe. Holotype is deposited at the National Museum of Natural History of Paris.

Chronotherapy of malaria: improved efficacy of timed chloroquine treatment of patients with Plasmodium falciparum infections.

The effect of routine treatment with chloroquine (10 mg/kg on days 1 and 2 and 5 mg/kg on day 3) on parasitaemia and parasitaemic profile of patients infected with Plasmodium falciparum was studied. As with P. vinckei petteri, the mid-term trophozoites of P. falciparum were the most susceptible stages to chloroquine treatment. It is suggested that, in order to diminish the frequency of drug administration and to lower the risks of chemoresistance developing, treatment should be diversified, using the drug which is most effective on the parasite stages present in the peripheral blood.

[Anopheles mascarensis (De Meillon, 1947): main vector of malaria in the region of Fort-Dauphin (south-east of Madagascar)]. / Anopheles mascarensis (De Meillon, 1947): vecteur principal du paludisme dans la région de Fort-Dauphin (Sud-est de Madagascar).

Anopheles funestus and Anopheles gambiae s.l. have been considered until now the major vectors of malaria everywhere in Madagascar. Anopheles mascarensis, a mosquito native to Madagascar, has been identified in Sainte-Marie island as a secondary vector only. In 1997, an entomological study was carried out to identify the malaria vectors in the area of Fort-Dauphin, South-East of Madagascar. Every month, mosquitoes were collected from landing catches on human volunteers (from 7:00 am to 5:00 pm inside dwellings and from 7:00 am to 0:00 pm outside) and from knockdown spray-collections indoors. An mascarensis was the most abundant mosquito, the average number of An. mascarensis bites per man/night was 7.6. The sporozoite index was 0.89%. Despite the presence of An. funestus and An. gambiae s.l., An. mascarensis was found to be responsible for 2/3 of the infectious bites (25 infectious bites per man/year). An. mascarensis is widely distributed ih Madagascar but only specimens from the east coast have been found to carry sporozoites of human malaria. Further arguments are thus advanced for the hypothesis according to which a sibling species of An. mascarensis is present in Madagascar.

[The reconquest of the Madagascar highlands by malaria]. / La reconquête des Hautes Terres de Madagascar par le paludisme.

A strong malaria epidemic with a high mortality rate occurred on the Madagascar Highlands in 1986-88. Vector control and free access to antimalaria drugs controlled the disease. The authors have searched for the causes of the epidemic to propose a strategy avoiding such events. The Highlands on Madagascar were known as malaria free. In 1878 a very severe epidemic flooded all the country. Development of irrigated ricefields which house both An. arabiensis and An. funestus had created a new anthropic environment. Moreover manpower imported from malarious coastal areas for rice cultivation and also for building large temples, could have brought P. falciparum. After several outbreaks the disease became endemic up to 1949. In 1949 a malaria eradication programme based on DDT spraying and drug chemoprophylaxis and chemotherapy was launched. By 1960 malaria was eliminated and DDT spraying cancelled. Only 3 foci were kept under surveillance with irregular spraying until 1975. The prophylaxis and treatment centres ("centres de nivaquinisation") were kept open up to 1979. The catholic dispensary of Analaroa, 100 km N.E. of Tananarive, opened in 1971 and worked without interruption up to now. The malaria diagnosis has always been controlled by microscopy. Its registers are probably the more reliable source of information on malaria in the area. They show that malaria was already present on the Highlands in 1971 but at a low prevalence; in 1980 when the "centres de nivaquinisation" were closed the number of cases increased by three times the progressive increase of the number of cases became exponential from 1986 to 1988 which was the peak of the epidemic; malaria remained at a high level until the end of 1993; yearly DDT spraying since 1993 have decreased the number of malaria cases among the dispensary attendants by 90%. The epidemic peak of 1988 was well documented by the Pasteur Institute of Madagascar around Tananarive. Before the epidemic started it was observed a come back of An. funestus which had been previously eliminated of most of the villages by DDT spraying. More than an epidemic the malaria increase in 1988 was a reconquest by malaria of the land from which it had been eliminated in the years 1950. This episode became dramatic because the lack of immunity of the population and the shortage of medicaments. The global warming which was advocated to explain the epidemic has no responsibility because the temperature on the Madagascar Highlands has not changed during the last 30 years. Also the cyclones do not seem to have played any role. It is very likely that the gradual decline of control measures, first DDT spraying, later drug distributions, had the main responsibility in the Highlands drama. Everywhere An. funestus reached a high level during the time where the parasite reservoir was rebuilding. They synergised each other. These findings should be taken in account in drawing the strategy planning for the next years.

[Stability and chemosensitivity of Plasmodium falciparum to chloroquine in 1990 and 1991 in Ankazobe, a village in high plateau Madagascar]. / Stabilité de la chimiosensibilité de Plasmodium falciparum a la chloroquine en 1990 et 1991 a Ankazobe, village des hauts plateaux malgaches.

The in vivo and in vitro response of Plasmodium falciparum to chloroquine was conducted in Ankazobe, a village located in the high plateau area. These studies confirmed the low level of chloroquine-resistance. The in vivo data indicate the absence of increase resistance during the 2 years study. Chloroquine is still the drug of choice for the treatment of malaria attack in this area.

[Anopheles funestus and rice agriculture in the Madagascar highlands]. / Anopheles funestus et la riziculture sur les plateaux de Madagascar.

An exhaustive study of the potential habitats of Anopheles funestus was led during 1992 in Ankazobe on the Plateau of Madagascar, 95 km northwest of the capital Tananarive. The rice fields provide more than 90% of the positive habitats versus less than 10% for the nonhuman biotopes. Larva are especially abundant on the surfaces of the rice during grain head formation and maturation. The dense vegetation coverage provides them with shade and protection against predators. After harvesting, the follows can be filled with water and wild vegetation, and then also provide an important share of the habitats. The rice fields are omnipresent on the Plateau where they supply the basis of local alimentation. A. funestus then constitutes a serious risk for all of the villages. The role of the rice fields as habitats for A. funestus has already been noted in Kenya but in West Africa the rice fields do not host this species, even if this species is very abundant in the other types of habitats.

[The impact of curtains impregnated with deltamethrin on the vectors and morbidity of malaria: results in Ankazobe, on the plateaus of Madagascar]. / Impact des rideaux imprégnés de deltaméthrine sur les vecteurs et la morbidité palustre: résultats à Ankazobe, sur les plateaux de Madagascar.

To evaluate the efficacy of deltamethrin impregnated curtains on malaria morbidity in a low transmission area, we studied volunteer families in the village of Ankazobe in the Madagascar Highlands from February 1993 to June 1994. After randomization, we provided 46 houses having 244 inhabitants with impregnated curtains (I) and 45 others having 257 inhabitants with nonimpregnated curtains (NI) as controls. We first estimated the number of mosquito bites in the protected versus nonprotected households. Every month, we captured mosquitos on humans in 6 houses per night for 4 nights. For the I group compared to the NI group, the number of bites by the Anopheles funestus vector per human per night was reduced by 64% in 1993 and 39% in 1994. We also analyzed the malaria morbidity. Malaria morbidity was defined as patients having both temperatures greater than 37.5 degrees C and Plasmodium falciparum parasitemia greater than 1500/microliter with clinical symptoms. From February to July 1993, we observed no significant difference in morbidity: there were 103 cases of malaria among 244 inhabitants of the I group and 117 cases among 257 inhabitants of the NI group. However, during the period of highest transmission from March to May in 1993, there were significantly fewer cases in the I group (68) than in the NI group (94). From January to June 1994, the difference was clear: only 35 malaria cases were observed among the 208 inhabitants of the I group as compared to 65 cases among the 223 inhabitants of the NI group (Chi square = 9.17, p = 0.0024). Inhabitants of the I group could have been contaminated before the curtains were set up. After treatment of the cases and use of curtains during the second year, we observed a reduction in the number of mosquito bites and malaria cases. The small size of the trial made the interpretation of the data difficult. Nonetheless, the results tentatively support the use of impregnated curtains as an antimalaria tool in an integrated control program.

[Malaria: research perspectives in medical entomology in Madagascar]. / Paludisme: perspectives des recherches en entomologie médicale a Madagascar.

The entomological studies on malaria in Madagascar had especially concerned the behavior of vectors in relation to insecticides. The cessation of spraying within the homes and the absence of chloroquine allowed a re-emergence of malaria on the Plateau in the 1980's. This phenomenon pointed out the heterogeneity of the transmission on the island. It was necessary to define the entomological characteristics of the four principal facies of transmission in Madagascar. These studies provided the services of public health with the epidemiological basis to organize the measures of the battle and prevention of malaria. In the very populated countryside of the Plateau, the nature of the vectors, their density and their vectorial competence present large local variations. The entomological studies search to define the different human and environmental factors which modulate the transmission and constitute the risk factors of epidemy. This micro-epidemiological approach will facilitate the analysis and comparison of the clinical and biological results obtained in the different residences. The research on medical entomology will equally enable the proposal of plans for the fight against malaria adapted to the different situations.

[Rice: source of life and death on the plateaux of Madagascar]. / Le riz source de vie et de mort sur les plateaux de Madagascar.

Since the 17th century, Europeans travelling in Madagascar described the contrast between the fever-free Plateau and the fever-ridden coasts. The former were inhabited by people of Asiatic origins and the latter by African migrants. At the end of the 18th century, "Merina" kings developed land irrigation and rice cultivation, using manpower from the coasts. Since then, rice has become a monoculture covering most of the arable lands of the Highlands. The first malaria epidemic occurred in the Tananarive area in 1878, and rapidly spread throughout the Plateau. The mortality rate was high. A second epidemic in 1895 may have been a resurgence of the previous one. Subsequently, malaria became meso-epidemic despite control measures, mainly consisting of larvivorous fishes, quinine treatment and prophylaxis. In 1949, an eradication program was launched based on DDT house-spraying and chloroquine prophylaxis in children. It was very successful on the Highlands where malaria disappeared, in 1962. Spraying was cancelled and only three small foci remained under surveillance. In 1987 and 1988, a malaria outbreak devastated the plateau. Subsequently, intensive spraying operations brought the situation under control by 1993. The main malaria vector on the Madagascar Highlands is An. funestus. More than 95% of its breeding sites are in the rice fields just before the harvest and afterwards in the fallow lands. The vector peak and the corresponding peak of malaria cases occur between February and May, depending on the farming calender. The second but less important vector, An. arabiensis, breeds in the rice fields just after seeding when the surface water is sunlit. Although rice fields remain the main source of this vector, it also breeds in rainwater pods and borow-pits. Malaria vectors on the plateau are products of human activities of rice cultivation, which is the basis of the economy. The epidemiological importance of rice fields varies greatly from one country to another. In Southeast Asia, the rice fields harbor several anopheline species most of which are only vectors of P. vivax. In West Africa where malaria is holoendemic, they produce large populations of An. gambiae; however, the malaria pattern is unaltered and remains at peak levels. In the dry areas of southern Madagascar, the vector An. funestus and meso-hyperendemic malaria are restricted to areas of cultivated rice. In West and Central Africa, An. funestus is never found in rice fields even though it is common in marshes. In Madagascar, this vector breeds in irrigated rice fields. Because it is practically impossible to control anophelines in rice fields by chemical, biological and ecological methods on the Highlands of Madagascar, house-spraying remains the best method for mass malaria control. Bed-nets impregnated with pesticides may offer an alternative, but their use is resisted by the local population.

[Drug resistance and therapeutic strategy]. / Chimiorésistance et stratégie thérapeutique.

In Madagascar, Plasmodium falciparum resistance to chloroquine was clinically suspected in 1975 by Goasguen and demonstrated in 1981 by Arronson et al. Since then, many studies were conducted throughout the island, in the North, South, East and West, on the high Plateau and on the coasts. Two methods were used, including an in vivo method similar to the therapeutic standard protocol of the WHO, and an in vitro method employing the semi-microtest of Le Bras and Deloron. From 1982 to 1986, the 291 in vivo tests performed showed that 20% of the strains were of the types R1 or R2 (SR1 included). From 1987 to 1994, of the 621 in vivo tests performed, 369 (59.4%) of the cases responded to treatment. The deterioration of the situation observed in 1988 (Lepers et al.) seemed to be stabilized (Ringwald et al.). No strain of the type R3 was found. In conclusion, we report the absence of strain type R3 and also the clinical efficacy of chloroquine. The action of chloroquine was spectacular on the fevers and there was remarkable reduction of the parasitaemia. Thus, for treating outbreaks of simple malaria in Madagascar, chloroquine remains the best choice if it is administered at an efficacious dose.

Zoophily of Anopheles arabiensis and An. gambiae in Madagascar demonstrated by odour-baited entry traps.

In Madagascar we used odour-baited entry traps (OBETs) for host choice tests of wild female anopheline mosquitoes (Diptera: Culicidae) at representative localities on the East and West sides of the island (villages Fenoarivo and Tsararano, respectively) and at the southern margin of the central plateau (Zazafotsy village, 800 m altitude). No insecticide house-spraying operations have been undertaken at these villages. Odours from a man and a calf of similar mass, concealed in different tents, were drawn by fans into separate OBETs set side by side. Traps were alternated to compensate for position effects, and different pairs of individual baits were employed for successive replicates. Totals of 266 An. funestus Giles sensu stricto and 362 An. gambiae Giles sensu lato were collected in 48 trap nights during March-June 1999. For each mosquito species the 'index of anthropophily' was defined as the proportion of females caught in the human-baited trap. For An. funestus this index was found to be consistently greater than 0.5 (value for random choice between traps/hosts), indicating that this species 'preferred' human to calf odour (index=0.83). Conversely, the index of anthropophily for An. gambiae s.l. indicated they 'chose' calf in preference to human odour (index=0.26). No significant differences of relative preference for calf or man were detected between villages; geographical variance accounted for <8% of the total experimental variance. Molecular identifications of 181 specimens of the An. gambiae complex (approximately 50% of the samples) revealed only An. arabiensis Patton at Tsararano and Zazafotsy, but >97% An. gambiae Giles sensu stricto at Fenoarivo, in accordance with prior knowledge of the differential distributions of these sibling species on the island. Predominant zoophily (i.e. intrinsic 'preference' for cattle odours) by both An. arabiensis and An. gambiae s.s. in Madagascar contrasts with their greater anthropophily in continental Africa.

[Insecticide sensitivity in malaria vectors in high altitude Madagascar after five years of vector control]. / Sensibilité aux insecticides des vecteurs du paludisme sur les Hautes terres de Madagascar après cinq années de lutte antivectorielle.

In 1991, Anopheles gambiae and Anopheles funestus, the main malaria vectors in the Highlands of Madagascar, were reported to be fully susceptible to DDT; nevertheless a slight decrease in the susceptibility levels was recorded when compared with previous assays carried out in 1962. From 1993 to 1997, five cycles of indoor residual spraying have been carried out in the Highlands: a total of 1,482,000 kg of 70% wp DDT have been used for the treatment of houses and animal shelters. From 1996 to 1999, adult mosquito susceptibility tests to DDT and to some pyrethroids (lambdacyalothrine, deltamethrine, permethrine and cyfluthrine) have been carried out on samples collected in 20 areas of the Highlands. Bioassays were carried out following the WHO standard method. All tested populations of An. funestus showed a full susceptibility to DDT. An. gambiae showed a widespread decrease in the susceptibility to DDT, particularly marked in the region of the capital city Antananarivo. Both species were susceptible to pyrethroids.

[Epidemiological malaria surveillance in 3 villages of the Madagascar highlands]. / Surveillance épidémiologique du paludisme dans trois villages des Hautes Terres Malagaches.

Results of the epidemiological surveillance of falciparum malaria carried out since 1987 in three villages of the malagasy Highlands are reported. They clearly show the unsteady endemo-epidemic characteristic of the disease with highly variable transmission levels according to foci. At Manarintsoa, a south-western village 20km away from the Capital, the disease has now fully disappeared after the ravage of 1986. But it might reappear with new imported cases and by lack of antivectorial measures. Although Anopheles arabiensis had been rare and its aggressivity rate weak (0.91-2 infecting bites per year per man), surveillance is indispensable for the future. An Ankazobe and Mahavelona, two north-western localities respectively 100km and 65km away from Antananarivo, malaria is endemic with periodic outbreaks during rainy season. At Ankazobe, Anopheles funestus is the main vector maintaining endemic in this area while the role of Anopheles gambiae l.s. is only secondary. At Mahavelona, because of the weak presence of vectors, the treatment protocol by Quinimax has been applied in order to study transmission. This study obviously shows that contrary to set ideas in the Highlands, backward transmission is possible up to the first months of the austral winter (June-July). In these two last villages, adults have acquired some premunition.

[Aspects of Plasmodium falciparum sensitivity to chloroquine in Madagascar from 1982 to 1993]. / Aspects de la sensibilité de Plasmodium falciparum à la chloroquine à Madagascar de 1982 à 1993.

According to pharmaco-sensitivity studies, about 20% of local Plasmodium falciparum strains showed a certain degree of resistance to chloroquine. No resistance of R3 type has never been observed. During this whole period, the decrease of sensitivity phenomenon remains stable. Because of its remarkable action on parasitemia and fever, chloroquine remains the best antimalaria in simple malarial attacks in madagascar.

Parasite virulence factors during falciparum malaria: rosetting, cytoadherence, and modulation of cytoadherence by cytokines.

To determine virulence factors of isolates of Plasmodium falciparum and the potential role of cytokines in cerebral malaria, 46 Malagasy patients presenting with cerebral (n = 10), severe (n = 10), and uncomplicated (n = 26) malaria were enrolled in a study. The capacity of 21 of 46 P. falciparum isolates to form rosettes in vitro and to adhere to human umbilical vein endothelial cells (HUVECs) that express intercellular adhesion molecule-1 receptors and to C32 amelanotic melanoma cells that express mainly CD36 receptors was investigated together with the effects of tumor necrosis factor alpha (TNF-alpha), granulocyte macrophage-colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-6 alone and in two-by-two combinations on the cytoadherence of infected erythrocytes to HUVECs. Plasma levels of these cytokines were also measured in the patients at admission. The percentage of rosette formation was higher for the isolates from patients with cerebral (n = 6; 19.5%) and severe (n = 6; 30.5%) malaria than for those from patients with uncomplicated malaria (n = 9; 5%) (P < 0.002). The cytoadherence properties of the isolates did not differ among the three groups whatever the target cell used, but adherence to melanoma cells was systematically higher than that to HUVECs. Adhesion to HUVECs was increased more after TNF-alpha stimulation than after GM-CSF, IL-3, or IL-6 stimulation (P < 0.01). Only the combination of TNF-alpha and IL-3 enhanced cytoadherence more than TNF-alpha used alone (P < 0.02). No difference in the modulation of cytoadherence by cytokines was found in relation to the severity of the disease. TNF-alpha and IL-6 levels in peripheral blood were higher in the patients with cerebral and severe malaria than in the patients with uncomplicated malaria (P < 0.005). Most of the patients' sera contained little or no IL-3 or GM-CSF. Our results challenge the role of intercellular adhesion molecule-1 as the principal receptor mediating the cytoadherence of P. falciparum-infected erythrocytes and contrast with data obtained in the murine model.