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.

The aim of this study is to highlight the recent progress in mapping vector-borne diseases in West Africa using modelling and field experiments. Based on climatic indicators, methods have been developed to map Rift Valley fever (RVF) and malaria risk. Modelling results corroborate that northern Senegal and southern Mauritania appear to be critical areas for RVF outbreaks and that the malaria epidemic fringe is located at the northern edge of the Sahel. Future projections highlight that the malaria risk decreases over northern Sahel. This is related to a southward shift of the potential epidemic belt in autumn. Copyright (C) 2010 Royal Meteorological Society

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 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.

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.

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.

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 2,000 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.

A comparative study of human-landing catches (HLCs) and odor-baited entry traps (OBETs) for sampling malaria vectors was conducted in two different bioclimatic areas of Senegal, the Sahelian and Sudano-Guinean phytogeographic zones, from September to December 2002. Mosquitoes were collected by the two methods both indoors and outdoors. The reliability of OBET samples was tested by comparing the two methods. Overall, HLC was more effective indoors and for surveying the anopheline fauna. Both methods were effective in sampling the four known malaria vectors in Senegal [Anopheles gambiae s.s., An. arabiensis Patton, An. funestus Giles, and An. nili (Theobald) ], and mosquito age structures and infectivity rates did not differ between methods.

Re-emergence of human cases of plague after decades of silence does not necessarily mean that plague foci are re-emerging. Most often, Yersinia pestis bacteria have been maintained and circulating at low levels in the rodent populations. It seems therefore more appropriate to speak in terms of expansion or regression phases for sylvatic rodent plague foci and to reserve the term re-emergence for human cases. From the analysis of well-documented human plague cases in Madagascar, we underline the causes of re-emergence that can be generalized to most world foci, and can help define environments at risk where the threat of new emergence lurks. In all recent plague outbreaks, usually more than one risk factor was at the origin of the re-emergence. The reduction or discontinuance of surveillance and control, as well as poverty and insalubrity are the main factors in the re-emergence of human cases, allowing increased contacts with infected rodents and fleas. Environment changes (i.e. climatic changes, deforestation, urbanization) induce changes in flea and rodent populations by (i) extension of rodent habitats (for example by replacing forests by steppes or farmlands); (ii) modifications in population dynamics (possible outbreaks due to an increase of available food resources); but also, (iii) emergence of new vectors, reservoirs and new Y. pestis genotypes. Numerous and spontaneous genomic rearrangements occur at high frequencies in Y. pestis, which may confer selective advantages, enhancing the ability of Y. pestis to survive, to be transmitted to new hosts, and to colonize new environments. Therefore, any environmental change should be taken as a warning signal and active surveillance programs should be initiated.

Les mâles de trois nouvelles espèces rares de Paractenopsyllus Wagner, 1938, genre endémique de Madagascar, sont décrits. Paractenopsyllus beaucournui, P. oconnori et P. raxworthyi ont été collectés à partir de micromammifères endémiques de Madagascar (excepté un rat noir) et, comme les autres espèces du genre, les biotopes de récolte se situent au sein des forêts des hautes terres centrales ou des massifs du Nord de l'île. Deux des trois espèces décrites ont été récoltées à des altitudes relativement basses pour le genre, à la limite de la zone écoclimatique des hautes terres. Les affinités morphologiques entre ces nouvelles espèces et celles déjà décrites permettent des rapprochements taxonomiques. Une clef de détermination des 20 espèces de Leptopsyllinae malgaches est présentée.

The Sahel is one of the African zones most exposed to climate change. Because of the obligatory aquatic phase of malaria mosquitoes, rainfall is thought to have a large effect on malaria prevalence, and drought seems to be associated with fewer mosquito bites. The disappearance of one the most dangerous African vectors, Anopheles funestus, from the Sahelian zone was imputed to the drought that has lasted three decades.1Mouchet J Faye O Juivez J Manguin S Drought and malaria retreat in the Sahel, west Africa.Lancet. 1996; 348: 1735-1736Summary Full Text Full Text PDF PubMed Scopus (55) Google Scholar In 1999, its comeback in Sahelian Senegal was suspected of being linked with the local development of irrigation systems.2Konate L Diop A Sy N et al.Comeback of Anopheles funestus in Sahelian Senegal.Lancet. 2001; 358: 336Summary Full Text Full Text PDF PubMed Scopus (14) Google Scholar We did a study in Niger during the 2003 rainy season to assess malaria vector presence and abundance across a south–north transect containing isohyet curves of 800–100 mm, corresponding to the most variable rainfall zone. 14 villages were sampled in the Soudanian, Sahelian, and Saharan regions. Members of Anopheles gambiae complex were found in all three zones, as expected. However, A funestus was also found in eight of the villages: all four of those in the Soudanian region and four of six in the Sahelian zone. This distribution is similar to that seen in the 1960s, but more recent studies have failed to show it. Irrigation is limited to the Niger valley and could not explain the comeback of A funestus in these regions. Although a global decrease in rainfall is still evident, groundwater levels are increasing in several areas of the Sahel.3Leduc C Favreau G Schroeter P Long-term rise in a Sahelian water-table: the continental Terminal in South-West Niger.J Hydrol. 2001; 243: 43-54Crossref Scopus (163) Google Scholar The clearing of natural wooded savannah and increases in cultivated areas have modified surface characteristics such that they tend to enhance water run-off. Temporary ponds are linked with groundwater recharge, and are now more numerous than they used to be and are present for longer. Many vectors are adapted to such breeding sites, which could lead to increase vector density. The greatest abundance of A funestus we found was in the Sahelian zone, in a village where this hydrological process is known to take place. Although the whole Sahel zone should not be concerned by the described hydrological process, the striking effect of local or subregional factors on transmission should be taken into account in malaria transmission models. At a time when transgenic mosquitoes are making the headlines in entomological malaria research, we would be wise to remember the interactions between anopheline populations and environmental factors.

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.