[Distribution of species and kdr gene frequency among Anopheles gambiae s.s. and Anopheles coluzzii populations in five agricultural sites in Côte d'Ivoire]. / Distribution des espèces et de la fréquence du gène Kdr chez les populations d'Anopheles gambiae s.s. et d'Anopheles coluzzii dans cinq sites agricoles de la Côte d'Ivoire.

The resistance of Anopheles gambiae s.l. to insecticides constitutes a concern for the programs of malaria control because it can be an obstacle to effective control of the vectors. The follow-up of this resistance is a priority to work out strategies of management and to preserve the means of that major malaria vector control activities. The general objective of this study is to identify the species within An. gambiae s.l., and to determine the frequency of the Kdr gene in An. gambiae s.s. and An. coluzzii in five agricultural sites in Ivory Coast: an urban site, two semirural sites (coffee-trees/cacao-trees, orchard) and two rural sites (rice site and a traditional village without agricultural insecticide). During this study, 2285 specimens of An. gambiae s.l. were analyzed for this purpose. An. gambiae s.s. (in the past called molecular form S) and An. coluzzii (in the past called molecular form M) were the only species of the complex An. gambiae identified in all the sites. The frequency of the Kdr mutation varied from 0.37 in the site without agricultural insecticide to 0.95 in the urban site where there is an intense use of insecticides. Three areas of these species distribution were observed: an area where the species An. gambiae s.s. is dominant (sites located in savanna), an area with predominance of An. coluzzii (in the southern forested area) and an intermediate area where the two species were in a same proportion (pre-forested site).The Kdr mutation was identified in the two species in all the sites in savanna and forest, except in the site without agricultural insecticide where only An. gambiae was resistant. It shows the increase of the receptive potential of An. gambiae s.l. with respect to the Kdr gene and the extension of the resistance to insecticide of this species in Ivory Coast.

Avoiding missed opportunities for immunization in the Central African Republic: potential impact on vaccination coverage.

Quantified in the study are the extent of missed opportunities for immunization and the potential increases in vaccination coverage and timeliness that could be achieved by using all health centre visits to administer childhood vaccinations in the Central African Republic. The data were collected during a national vaccination coverage survey of 642 children aged 12-23 months from three areas: rural, urban, and the capital, Bangui. Dates of all vaccination visits and other health centre visits were obtained from combined vaccination/health cards. Nationwide, 70% of all opportunities for valid measles vaccination were missed. Of these, 28% occurred at visits when at least one vaccine was given, while 72% occurred at other health centre visits. If there had been no missed opportunities to administer all vaccinations due when at least one vaccine was given, the coverage would have increased from 53% to 67% for the diphtheria-pertussis-tetanus series, from 54% to 70% for measles, and from 34% to 59% for all antigens. If there had been no missed opportunities at any visit, the corresponding increases would have been to 70%, 76%, and 65%. For measles, 46% of the potential increase depends on recognizing that an earlier dose of the vaccine was invalid and on revaccinating. Days-at-risk for measles (after the age of 270 days) would have been reduced by a mean of 74 days per subject with a health card had no opportunities been missed. The method used serves as a valuable adjunct to evaluations of missed opportunities based on exit interviews at health facilities.(ABSTRACT TRUNCATED AT 250 WORDS)

PIP: The Central African Republic in 1986 initiated an accelerated immunization program which became fully operational in 1988. As part of the program, a policy of vaccinating eligible children at all health facility contacts was adopted. National surveys conducted in 1985 and 1989 indicated that there had been a substantial increase in vaccination coverage, but that immunizations were not being given at all visits on a widespread basis. The authors quantify the extent of these missed opportunities for immunization and the potential increases in vaccination coverage and timeliness which could be achieved if all health center visits were used to administer childhood vaccinations in the Central Africa Republic. Study data were collected during a national vaccination coverage survey of 642 children aged 12-23 months from rural and urban areas as well as Bangui, the capital. Dates of all vaccination and other health center visits were obtained from combined vaccination/health cards. Analysis found that 70% of all opportunities nationwide for valid measles vaccination were missed. Of these, 28% occurred at visits when at least one vaccine was given and 72% occurred at other health center visits. If there had been no missed opportunities to administer all vaccinations due when at least one vaccine was given, coverage would have increased from 53% to 67% for the diphtheria-pertussis-tetanus series, from 54% to 70% for measles, and from 34% to 59% for all antigens. If there had been no missed opportunities at any visit, the corresponding increases would have been 70%, 76%, and 65%, respectively. For measles, 46% of the potential increase depends on recognizing that an earlier dose of the vaccine was invalid and on revaccinating. Days at risk for measles after the age of 270 days would have been reduced by a mean of 74 days per subject with an health card had no opportunities been missed.