Longitudinal follow-up of malaria transmission dynamics in two villages in a Sahelian area of Niger during a nationwide insecticide-treated bednet distribution programme.

Malaria transmission was monitored in two villages in the Sahel zone of Niger over 4 years. During this period, a nationwide vector control programme was carried out in which insecticide-treated bednets were distributed free to mothers of children aged <5 years. Anopheles gambiae and Anopheles arabiensis (Diptera: Culicidae) were found to be the major malaria vectors. The dynamics of An. gambiae s.l. did not vary dramatically over the study period although the proportion of female mosquitoes found resting indoors decreased in both villages and, in one village, the parity rate and sporozoite index were significantly reduced after bednet distribution. By contrast with An. gambiae, the dynamics of Anopheles funestus altered greatly after the bednet distribution period, when adult density, endophagous rate and sporozoite rates decreased dramatically. Our observations highlight the importance of quantifying and monitoring the dynamics and infections of malaria vectors during large-scale vector control interventions.

Anopheles hervyi in Niger: no evidence for a role in Plasmodium falciparum transmission.

Anopheles hervyi is an endemic mosquito species with a very limited spatial distribution in the south east of Niger. No new captures have been reported since the 1960s and its role in malaria transmission has not been studied. In the present study, the use of CDC light traps showed it to be much more abundant than previously found but there was no evidence to suggest it was a malaria vector in this region. The larval habitats have not been identified but the potential role of a saline lake in determining the distribution of this species is discussed.

[Plasmodium falciparum chloroquine and pyrimethamine resistance monitoring network with molecular tools in the Niger River valley, Republic of Niger]. / Réseau de surveillance moléculaire de la chimioré- sistance de Plasmodium falciparum a la chloroquine et a la pyriméthamine dans la vallée du fleuve Niger, au Niger.

Plasmodium falciparum resistance to chloroquine first arose in Africa 25 years ago. Nowadays most of African malaria control programmes have switched their first-line treatment of uncomplicated malaria cases towards artemisinin derivatives combination. After WHO guidelines, a survey network for malaria treatment resistance has been set up in the Niger valley around Niamey since December 2004. The association of the Niger national malaria control programme with the CERMES research center allowed collecting of samples from both health centers and hospitals of this region. Blood finger-pricks on filter papers were tested for detection of plasmodial antigen in health center without biological diagnosis capacity. Specimens found positive either in hospital laboratory or by using antigen method were tested by PCR/RFLP to detect K76T mutations on the pfcrt gene and S108N mutation on the pfdhfr gene. This simple procedure allows the screening of a large number of specimens. Moreover, a spatial distribution of mutations and evidence of resistance clusters were searched integrating the data in a geographic information system. The 76T mutation of pfcrt and 108N of pfdhfr were respectively found in 50.8% and 57% of the specimens tested. No statistically significant difference was found according to the level of sanitary formations or the age of the patients. No resistance cluster was identified and the prevalence of mutation seems homogeneous in the zone. By completing the clinical efficacy studies we think that our simple method for collecting and testing blood samples associated with clinical efficacy studies may be useful for building a network of malaria drug resistance in Africa.

[French language training course: malaria workshop organized by Institut Pasteur de Madagascar]. / Formation francophone Sud/Sud: l'atelier paludisme de l'Institut Pasteur de Madagascar.

The Malaria Workshop organized by Institut Pasteur de Madagascar is an original course that applies innovative concepts to training of health professionals involved in malaria control in endemic countries. Course objectives are to enhance the skills needed to fight malaria (transversal competencies, critical approach, and position statement), to reinforce project cycle management proficiency, and to demonstrate how the Internet can be used as a source of documentation to compensate for geographical isolation. The Malaria Workshop is a six-consecutive-week full-day course that has been presented once a year since 2003. Seventy-six researchers, physicians or health ministry officials have already benefited from this training. Teaching methods emphasize andragogy that facilitates a learner/mentor relationship promoting exchange rather than transmission of knowledge and problem-based learning that engages learners to take an active part in gathering information. These methods in combination with the diverse backgrounds and experience of course participants foster a positive dynamic environment for learning that is monitored by weekly progress evaluation. Follow-up surveys have confirmed the positive effect of this training on the professional performance of former participants who become more involved in program development and fund-raising efforts. A professional network is growing and learners are starting to their experience. In this report workshop organizers describe the course's origins and concepts and present the conclusions drawn based on the first five yearly sessions.

ELISA study of oocyst-sporozoite transition in malaria vectors.

Intrinsic vector characteristics and environmental factors affect the sporogonic development of P. falciparum in Anopheles mosquitoes. We tested for the presence of the circumsporozoite protein, as a marker of the oocyst to sporozoite transition in naturally infected Anopheles gambiae s.l. and Anopheles funestus. Malaria vectors were collected in a village in the Sahel of Niger during the rainy and dry seasons. ELISA-CSP was carried out on abdomen and head/thorax portions from more than 2000 samples. No significant difference was found in the overall rates of infection of An. gambiae s.l. (4.13%) and An. funestus (3.58%). Given the differences in duration of the two parasite stages, P. falciparum CSP antigen prevalence was nearly as high in the abdomen as in the head/thorax, and did not differ significantly between An. gambiae s.l. and An. funestus. These preliminary results suggest that development from oocysts to salivary gland sporozoites is similar in the two vectors. However, these developmental indices varied as a function of the season in which samples were collected, particularly for An. gambiae s.l. This simple method may be useful for field studies assessing the effect of environmental and genetic factors on parasite survival.

[Fleas and diseases transmissible to man]. / Les puces et les maladies transmises à l'homme.

Fleas are wingless insects that parasitize mammals and more rarely birds. They are able to jump and may bite people. Adult fleas are hematophagous. The impact of fleas on public health is related to their ability to act as vectors for transmission of infectious agents during blood meals. The purpose of this article is to describe fleas and the diseases that they transmit to humans. Special focus is placed on epidemiological aspects.

[Description of three new species of Paractenopsyllus genus (Siphonaptera: Leptopsyllinae) from Madagascar]. / Description de trois nouvelles especes de Paractenopsyllus (Siphonaptera: Leptopsyllinae) de Madagascar.

The males of three new and rare species of the Malagasy endemic genus Paractenopsyllus Wagner, 1938 are described. Paractenopsyllus beaucournui, P. oconnori and P. raxworthyi have been collected on endemic small mammals and the black rat. As for others species of the genus, biotopes are rain-forests of the central highlands or the northern mountains of Madagascar. Two of the described species were collected at elevations lower than typical for the genus and below the limits of the highland bioclimatic zone. Morphological affinities between these new species and those already described provide taxonomic framework for the genus. An updated identification key is provided for the diagnosis of all the 20 Malagasy species of Leptopsyllinae.

Leptopsyllines from Madagascar (Insecta: Siphonaptera: Ceratophyllidae): description of five new species of Paractenopsyllus Wagner, 1938.

Five new species of the malagasy endemic genus Paractenopsyllus Wagner, 1938, are described. Paractenopsyllus rouxi, P. ratovonjatoi, P. duplantieri, P. juliamarinus and P. gemelli have been collected on endemic small mammals and the black rat. Biotopes are mid-elevation rain-forests of the central highlands or the northern mountains of Madagascar. Morphological affinities between these new species and those already known provide taxonomic links within the genus. Differences in the spatial and altitudinal distributions and host ranges allow discussion of the potential factors important in the species distribution of this genus.

Malaria transmission in Southern Madagascar: influence of the environment and hydro-agricultural works in sub-arid and humid regions. Part 1. Entomological investigations.

A 4-year entomological study was carried out in Southern Madagascar to identify malaria vectors, evaluate the transmission and compare the influence of irrigation in the sub-arid and adjacent humid regions. Three villages were involved in this entomological survey: Androvasoa (located in the natural sub-arid ecosystem), Pépiniére (sited at the centre of an irrigated rice scheme in the sub-arid region) and Esana (bordered with rice fields in the humid region). Mosquitoes were collected inside and outside dwellings when landing on human beings, with light traps and with knockdown indoor sprays. Anopheles arabiensis, Anopheles merus and Anopheles funestus were found in every village while Anopheles gambiae s.s. was only found in the village bordering the rice-fields (Pépiniére) and Anopheles mascarensis, a mosquito native to Madagascar, was only found in the humid region (Esana). In Pépiniére, the annual entomological inoculation rate (EIR) was low (EIR=0.4 infective bites/man/year (IBM)). In the irrigated scheme of the sub-arid region, malaria transmission was 150 times higher (mean EIR=63 IBM) than in the natural ecosystem and A. funestus was the main vector, responsible for 90% of infective bites. In Esana, the level of malaria transmission was high (EIR=41 IBM) and 2/3 of the infective bites were due to A. mascarensis, despite the presence of A. gambiae s.s. and A. funestus. These results are discussed with reference to the impact of irrigation on malaria in Africa ("the paddies paradox").

[Molecular characterization of mosquitoes of the Anopheles gambiae complex from Mayotte and Great Comoro]. / Caractérisation moléculaire des moustiques du complexe Anopheles gambiae à Mayotte et à Grande Comore.

The mosquitoes of the Anopheles gambiae complex have been characterised at specific and sub-specific levels in two islands of the Comoros archipelago: the island of Mayotte (French departmental collectivity) and the island of Grande Comore (Comoros Union). Results are similar in the two islands and are presented together. The species An. gambiae s.s. was observed alone (determination performed on 149 specimens by PCR product of IGS of rDNA). The molecular form observed alone was S, and corresponds in this geographic area to the chromosomal form Savanna (determination performed on 123 specimens by another PCR product of IGS of rDNA). The haplotype IB was observed alone (determination performed on ten specimens, by sequencing the ITS of rDNA, with special attention at the position 871 of ITS), as previously observed by other authors in East Africa. Finally, in Mayotte and Grande Comore the An. gambiae complex is only composed by An. gambiae s.s. from the molecular form S/type IB.

[Systematics and biology of Anopheles vectors of Plasmodium in Africa, recent data]. / Systématique et biologie des anophèles vecteurs de Plasmodium en Afrique, données récentes.

Renewed interest in research on Plasmodium vectors in Africa and development of genetic and molecular biology techniques has been spearheaded by the WHO and the PAL+ program of the French research ministry. New findings have led to a better understanding of the systematics and biology of the main vector groups. The purpose of this article is to describe the newest data on the Anopheles gambiae complex and the M and S forms of An. gambiae s.s., on species in the An. funestus group and genetic polymorphism of An. funestus, on the two probable species in the An. moucheti complex, and on An. mascarenesis.

[Plague control in Madagascar: evaluation of the efficacy of Kartman baitboxes in urban areas]. / Lutte contre ia peste à Madagascar: évaluation de l'efficacité des boîtes de Kartman en milieu urbain.

A method associating an anticoagulant rodenticide and an insecticide called Kartman bait-box aimed both at fighting reservoir and vectors of plague. It was evaluated in two neighbourhoods of Antananarivo (Madagascar) from October 2002 to May 2003. It involved the local community in the control. The study was carried out in Ambodirano-Ampefiloha refered as treated neighbourhood in which the Kartman bait box were laid out with an anticoagulant rodenticide and an insecticide with a rapid action versus a "pilot neighbourhood", Ankorondrano-Andranomahery in which the boxes were provided with non poisoning bait and non insecticidal white powder. The rodenticide used was Baraki (difethialone 25 ppm) and the insecticide was a powder of Propoxur 3%. The evaluation of effectiveness of this method was based on the four following parameters: (1) the number of dead rats collected daily inside and in the vicinity of the houses, (2) the daily number of baits non consumed in the Kartman bait box, (3) the cheopis index of the rats trapped using the BTS trap, and (4) the flea carrier index of the rats captured monthly with BTS trap. The cheopis index and the flea carrier index of the rats were calculated monthly. The number of rats that died in the treated neighbourhood was of 968 versus 3 in the pilot neighbourhood. The other parameters reached a stable level after 3 months. Between days 120 and 180, the mean number of unconsumed baits was 2.79 in the treated neighbourhood versus 0.14 in the pilot neighbourhood, the flea carriage (percentage of parasitized hosts) was 0% versus 61% in the pilot neighbourhood, and the cheopis index was 0.0 versus 5.0 in the pilot neighbourhood. This study demonstrates that Kartman bait-boxes reached the rat borne and the vectors of plague found in urban area. We propose to use this method extensively both during epidemic and inter-epidemic contexts.

[Anopheles mascarensis of Meillon 1947, a malaria vector in the middle west of Madagascar?]. / Anopheles mascarensis de Meillon 1947, vecteur de paludisme dans le Moyen-Ouest de Madagascar?

Anopheles mascarensis has been demonstrated to be a vector of human malaria in the East coast of Madagascar. Here, we present original data obtained from 1996 to 2003 on the distribution, biology and vectorial capacity of An. mascarensis in the Middle-West of Madagascar. This species is consistently exophilic both for its trophic and resting behaviour. This accounts for the absence of clear impact of any indoor insecticide spraying. This species is mainly zoophilic, but can occasionally bite humans, which explains a low sporozoitic index (1/2218 = 0.045%). The densities of human landing mosquitoes are most of the time very low, with the exception of a peak between May and August at the beginning of the dry season. It implies that the vector's efficiency is very low but not insignificant in the Middle-West of Madagascar, a situation opposite to what is observed on the East coast. The vectorial efficiency of An. mascarensis and An. arabiensis would enable to maintain a low malarial endemicity in the Middle-West, even in the complete absence of An. funestus.

Two new fleas (Siphonaptera: Ceratophyllidae: Leptopsyllinae) of Madagascar: Tsaractenus rodhaini n. sp. and Paractenopsyllus (Consobrinopsyllus n. subgen.) goodmani n. sp.

Following considerable sampling in Malagasy forests, two new species of endemic fleas from Madagascar are described. These are T. rodhaini n. sp. and P. goodmani n. sp., collected on small mammals. The material of T. rodhaini allows us to describe the previously unknown female of the genus Tsaractenus. We also complete the initial description of the genus with new diagnostic characters. Although it belongs to Paractenopsyllus, P. goodmani shows many unique characteristics. To help resolve certain systematic issues involving Malagasy Leptopsyllinae we introduce the new subgenus Consobrinopsyllus of Paractenopsyllus for P. goodmani. Its particular condition makes us consider valuable characters of the genus Tsaractenus. Carrying several traits of this genus, P. goodmani could constitute an intermediate step between the two endemic Malagasy leptopsylline genera. Considering these new findings the actual taxonomic position of the Malagasy genera among the Leptopsyllinae is discussed.

Lutte contre la peste à Madagascar : évaluation de l'éfficacité des boîtes de Kartman en milieu urbain

La boîte de Kartman associe, dans un même réceptacle, un rodenticide à action lente et un insecticide à action rapide. Elle offre l'opportunité de lutter contre les réservoirs et contre les vecteurs de la peste. Cette méthode a été évaluée dans deux quartiers de la ville d'Antananarivo en associant la communauté à cette lutte. Le rodenticide utilisé a été le diféthialone 25 ppm (Baraki®) et l'insecticide, un carbamate en poudre à une concentration de 3% (Propoxur ®). Le schéma de l'étude réalisée d'octobre 2002à mai 2003 repose sur une comparaison entre un "quartier traité" et un "quartier témoin".L'analyse a porté sur 4 variables : (1) le nombre quotidien de rats trouvés morts, (2) le nombrequotidien d'appâts non consommés restant dans les boîtes, (3) la prévalence des rats porteurs de puces, et (4) l'index pulicidien des rats. Les variables 3 et 4 ont été obtenues à partir de rats piégés vivants à une fréquence mensuelle. Le nombre de rats morts dans le quartier traité a été de 968 versus 3 dans le quartier témoin. Les autres variables étudiées ont atteint un niveau d'équilibre à partir du 4 ème mois. Ainsi, entre J120 et J180, la moyenne quotidienne du nombre d'appâts non consommés a été de 2,79 dans le quartier traité versus 0,14 dans le quartier témoin, la prévalence des rats porteurs de puces a été de 0% dans le quartier traité (n=2 rats) versus 61% dans le quartier témoin(n=42 rats), et l'index pulicidien de ces rats dans le quartier traité a été 0 versus 5,0 dans le quartier témoin. Cette étude démontre l'efficacité de cette méthode pour atteindre les réservoirs et les vecteurs de la peste urbaine. Sous réserve d'utilisation correcte, la boîte de Kartman a sa place parmi les moyens de lutte contre la peste dans les contextes inter-épidémiques ou épidémiques

[Value of HPLC and fluorescent pteridines in estimating the age of Anopheles gambiae adults]. / Intérêt de l'HPLC et des ptéridines fluorescentes pour estimer l'âge d'anophèles adultes de l'espèce Anopheles gambiae.

Fluorescent pteridines are photosensitive pigments of mosquito cuticle. Their quantity decreases with time during the adult life of mosquitoes. In order to test the feasibility of the reversed-phase HPLC (High Pressure Liquid Chromatography) technique, to measure pteridine fluorescence and to estimate the calendar age, reared Anopheles gambiae of known age are used. Head and thorax were studied on mosquitoes aged 0, 5, 10, 20 days after emergence. There was significant difference between male and female of 0 and 5 days of age; the difference was not significant at 10 days of age. The level of fluorescence between a female's head and thorax non separated does not differ from the sum of fluorescence level of separated head and thorax. Pteridin fluorescent of female's head and thorax does not correlate. It decreases significantly with chronological age between 0 and 5 days either for head + thorax or for head alone. Conversely, this fluorescence quantity is weak and maintained constant beyond 5 days. The use of thorax alone of the female mosquito allows the differentiation of mosquito aged less than 5 days, between 5 and 10 days and aged more than 10 days. Reversed-phase HPLC technique, at least in the way we have demonstrated, does not appear sensitive enough to estimate the age of the species An. gambiae reared in an insectarium. It seems that this technique, relatively complex to manage, does not bring a substantial advantage compared to the method of Detinova, which allows the separation of nulliparous and parous females (i.e. < or = 3 days versus > 3 days).

[Review of genus Coquilletidia (Diptera: Culicidae) in Madagascar and description of the larva of Cq. grandidieri (Blanchard, 1905)]. / Revue du genre Coquilletidia (Diptera: Culicidae) à Madagascar et description de la larve de Cq. grandidieri (Blanchard, 1905).

The genus Coquilletidia includes some of the mosquitoes involved in the transmission of numerous arbovirosis. Adults are locally abundant and very aggressive for men. In Madagascar, thus genus concerns 3 species among which 2 are endemic and had not been described at larval stage this far. The authors describe a single larva of Coquilletidia collected at Ankazobe in the Middle West of Madagascar, at an altitude of 1200 meters. The geographical distribution of Coquilletidia adults collected in various bio-climatic zones in Madagascar, combined with observed morphological characters, permit us to attribute this larva to Cq. grandidieri.

[Malaria study in the cyclone risk zone: entomological , diagnostic and therapeutic approach in the southeastern region of Madagascar]. / Etude du paludisme en zone de risque cyclonique: approche entomologique, diagnostique et thérapeutique dans la région Sud-Est de Madagascar.

Madagascar is a tropical island affected by many natural disasters. The eastern coastal zone--an area of perennial malaria transmission--is regularly exposed to cyclones. Few malaria studies have been done in this area of Madagascar, and none have examined the potential relationship between malaria and natural disasters. A mobile team spent six weeks in the fields doing three lines of research: an entomological study by catching mosquitoes and determining their species: a therapeutic study of chloroquine (CQ) and sulphadoxine-pyrimethamine (SP) according to a 14 days WHO protocol and also a study of physician's diagnostic ability. Physicians were asked to make a presumptive clinical diagnosis of all febrile patients, and these results were compared to those obtained from blood smear examinations. The entomological study found three major vectors species: Anopheles gambiae, An. funestus and An. mascarensis. The therapeutic study showed that SP was 100% effective (n = 13) and only one case of CQ treatment failure was recorded (1/15). Finally the diagnostic study demonstrated that presumptive diagnosis of malaria based on the only clinical signs leads to an over-estimation of malaria frequency. Over 68% (102/149) of febrile patients were diagnosed by physicians to have malaria while only 52 (34.9%) were proven positive. Of the 47 patients diagnosed clinically as malaria-negative, 12 (25.5%) turned out to be positive. Outbreaks of malaria during or after natural disasters in Madagascar can be successfully treated with either CQ or SP, but compliance may be better with SP since it requires only one dose. Perhaps equally important in the context of natural disasters is to have the capacity to make a definitive diagnosis, and the dipsticks should be made available.