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M Diallo

Publications and source records attributed to M Diallo.

At least 37 records · Page 2Linked to original sources
PubMed2001

Preliminary lack of evidence for simian odour preferences of savanna populations of Anopheles gambiae and other malaria vectors.

The behavioural response to several culicine and anopheline mosquitoes to the odour of alternative hosts (human vs monkey) arranged in a choice set-up using odour-baited entry traps (OBETs) was assessed in a field experiment in south-eastern Senegal. The experimental protocol followed procedures analogous to those adopted in olfactometer laboratory tests. Two adult Cercopithecus aethiops and a child of similar mass slept inside separate tents and their odours were drawn to each one of two paired OBETs so that approaching mosquitoes could experience both odour-laden streams before "choosing" to fly against one of the two air currents and into the trap. The traps were set up in a riverine forest clearing near the town of Kedougou, where primates (Papio papio, Cercopithecus aethiops, and Erythrocebus patas) are common. A total of 192 mosquitoes belonging to 4 genera was captured during 8 trap nights. All major human malaria vectors including Anopheles gambiae sensu lato, An. funestus, and An. nili, which constituted the bulk of the trap catch (N = 153), clearly expressed a preference for human odour, with > 90% of captured mosquitoes caught in the human-baited trap. A sub-sample of specimens belonging to the An. gambiae complex caught in both traps was identified by rDNA-PCR and RFLP as An. gambiae sensu stricto molecular form S (7/10), and An. arabiensis (3/10). The only species that did not show a preference for the alternative odour-laden air streams, among those caught in significant numbers, were mosquitoes of the genus Mansonia, with both Ma. uniformis and Ma. africana weakly preferring human odour, but not at a statistically significant level. These results are in accordance with the hypothesis that the strongly anthropophilic feeding preferences of An. gambiae did not evolve from an ancestral association with non-human primates.

Aedes↗
PubMed2000

Vertical transmission of the yellow fever virus by Aedes aegypti (Diptera, Culicidae): dynamics of infection in F1 adult progeny of orally infected females.

Vertical transmission of yellow fever virus from orally infected females to their progeny was experimentally demonstrated in 2 Aedes aegypti colonies from the Dakar and Koungheul regions in Senegal. A total of 10,530 F1 adult mosquito progeny were tested. The overall vertical transmission rate was 0.97%, with no significant difference between the Dakar and Koungheul colonies. The infection rates were significantly higher in females (1.15%) than in males (0.74%) in both colonies. The virus was not isolated from the progeny of the first oviposition cycle (OVC1). The true infection rates were 0.27% and 1.99%, respectively, for the OVC2 and OVC3 progeny in the Dakar colony, and 1.1% and 1.48%, respectively, for the OVC2 and OVC3 progeny in the Koungheul colony. The infection rates increased with extrinsic incubation in both male and female offspring of the 2 colonies, reaching 5.2% in 20-day-old OVC3 female progeny in the Dakar colony. The epidemiologic consequences of these results are discussed.

Aedes↗
PubMed2000

First isolation of the Rift Valley fever virus from Culex poicilipes (Diptera: Culicidae) in nature.

Following the reemergence of Rift Valley fever (RVF) virus in southeastern Mauritania in 1998, an entomological survey was undertaken in the boundary area in Senegal to assess the extent of the virus circulation. During this study, RVF virus (36 strains) was isolated for the first time from Culex poicilipes in nature. The possible role of Cx. poicilipes as an RVF vector is discussed regarding its biology and ecology.

Animals↗
PubMed2000

[Reinfection with Schistosoma haematobium and mansoni despite repeated praziquantel office treatment in Niger, Mali].

The dynamics of reinfection by Schistosoma haematobium and Schistosoma mansoni after repeated treatment with praziquantel (40 mg/kg body weight, single dose) was studied in a cohort of schoolchildren living in an endemic area. A total of 214 urine and 220 stool samples were collected and examined at three different times, i.e., February 1989, July 1989 and February 1990. Mass chemotherapy was administered at the beginning of study (February 89). Treatment was repeated in children with positive tests at each subsequent sampling. Prevalence rates were 55.1 p. 100, 3.7 p. 100, and 35.0 p. 100 for Schistosoma haematobium and 62.7 p. 100, 46.3 p. 100 and 73.1 p. 100 for Schistosoma mansoni in February 1989, July 1989 and February 1990 respectively (p < 0.001). From July 1989 to February 1990, reinfection was observed in 84.5 p. 100 of children by Schistosoma haematobium versus 57.8 p. 100 by Schistosoma mansoni. The risk of reinfection by Schistosoma haematobium was higher in children between the ages of 7 and 10 years than in children between the ages of 11 and 15 years (p < 0.001), The incidence of intense Schistosoma haematobium egg excretion rose from 0 p. 100 in July 1989 to 6.0 p. 100 in February 1990. The incidence of intense Schistosoma mansoni excretion in February 1990 was 4.5 p. 100. The reinfection rate at 7 months was over 50 p. 100 for both parasite species despite repeated treatment. This finding demonstrates that additional measures such as proper sanitation and vector control are needed to control human schistosomiasis in irrigated rice paddies.

Adolescent↗
PubMed1999

Vectors of Chikungunya virus in Senegal: current data and transmission cycles.

Chikungunya fever is a viral disease transmitted to human beings by Aedes genus mosquitoes. From 1972 to 1986 in Kédougou, Senegal, 178 Chikungunya virus strains were isolated from gallery forest mosquitoes, with most of them isolated from Ae. furcifer-taylori (129 strains), Ae. luteocephalus (27 strains), and Ae. dalzieli (12 strains). The characteristics of the sylvatic transmission cycle are a circulation periodicity with silent intervals that last approximately three years. Few epidemics of this disease have been reported in Senegal. The most recent one occurred in 1996 in Kaffrine where two Chikungunya virus strains were isolated from Ae. aegypti. The retrospective analysis of viral isolates from mosquitoes, wild vertebrates, and humans allowed to us to characterize Chikungunya virus transmission cycles in Senegal and to compare them with those of yellow fever virus.

Aedes↗
PubMed1999

Pyrimethamine-sulfadoxine efficacy and selection for mutations in Plasmodium falciparum dihydrofolate reductase and dihydropteroate synthase in Mali.

To assess pyrimethamine-sulfadoxine (PS) efficacy in Mali, and the role of mutations in Plasmodium falciparum dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) in in vivo PS resistance, 190 patients with uncomplicated P. falciparum malaria were treated with PS and monitored for 56 days. Mutation-specific polymerase chain reactions and digestion with restriction endonucleases were used to detect DHFR and DHPS mutations on filter paper blood samples from pretreatment and post-treatment infections. Only one case each of RI and RII level resistance and no cases of RIII resistance or therapeutic failure were observed. Post-PS treatment infections had significantly higher rates of DHFR mutations at codons 108 and 59. No significant selection for DHPS mutations was seen. Pyrimethamine-sulfadoxine is highly efficacious in Mali, and while the low level of resistance precludes assessing the utility of molecular assays for in vivo PS resistance, rapid selection of DHFR mutations supports their role in PS failure.

Animals↗
PubMed1999

[Aspects of genital tuberculosis in women].

Thirteen cases of genital tuberculosis are reported to make emphasis onto the difficulties of diagnosis, management and prognosis of the disease. The average age of the patients is 31 years. Most of them were under 30. The circumstances of diagnosis were variable. The diagnosis was essentially made thanks to histology. The evolution was favorable under antibiotics. But clinical sequels as amenorrhea and infertility are frequent.

Adolescent↗
PubMed1999

[Chikungunya virus outbreak in Senegal in 1996 and 1997].

Chikungunya disease is generally recognized in Africa by serosurveys conducted in rural areas. Epidemics are rarely documented. We report two outbreaks in Senegal: one having occurred near Kaffrine in 1996 during an epidemic of yellow fever (YF), the second in Niakhar in 1997. Both diagnoses were conducted by IgM antibodies captures and confirmed by virus isolations. In Kaffrine, a randomised study was carried out on 447 blood donors whose serum was systematically tested for the most frequently encountered arboviruses in Senegal. The incidence rate was higher for the unrecognized Chikungunya infection (35.3%) than for the notified YF infection (21%). In Niakhar, Chikungunya infection was initially detected through three cases having occurred in health workers. A serosurvey was then conducted to define the area of prevalence. We report the clinical forms of Chikungunya virus infections, the interest in detecting IgM for recent arbovirus infections and the duration of these IgM. The difficulties of diagnosis of Chikungunya infection in malaria endemic areas are stressed. The occurrence of arbovirus infections, Yellow fever and Chikungunya viruses, transmitted by the same vectors (Aedes aegypti) in Kaffrine are also discussed.

Aedes↗
PubMed1998

Yellow fever outbreak in Kaffrine, Senegal 1996: epidemiological and entomological findings.

In November 1996 a yellow fever (YF) outbreak occurred near Kaffrine in the central part of Senegal. Thirty-six deaths were notified, all children under 15 years of age. The YF diagnosis was confirmed by MAC-ELISA or by virus isolation. The immune status against YF virus of a sample population of 449 individuals was determined, and 31 confirmed cases and 69 asymptomatic cases were reported. Distribution of YF cases and incidence rate decreased with age, while the attack rate was stable in all age groups. Larva indices were high and Aedes aegypti was common in all villages, causing man-to-man transmission. The greatest risk of YF disease was lack of immunity, especially in individuals <20 years of age. The outbreak was rapidly controlled by an emergency immunization campaign. YF epidemics occurred in Senegal over two consecutive years. The last outbreak reached the main road to Dakar and the risk of spread to urban areas has increased.

Adolescent↗
PubMed1998

Odor-mediated host preferences of West African mosquitoes, with particular reference to malaria vectors.

The role of odors in mosquito host preferences was studied in a village near Ouagadougou, Burkina Faso. Two odor-baited entry-traps were put beside one another and a choice of host odor-laden air was blown out of them. Odors of a human and a calf (of similar mass) were drawn from two tents in which each was separately concealed. Allowances were made for trap position, differences in human-subject attractiveness, CO2 levels, and trap contamination with alternative host odors. Choices for the human-baited trap greater than the 0.5 random expectation were made by Anopheles gambiae s.l. (0.96) and An. pharoensis (0.68). The choices for the human-baited trap of Culex antennatus were significantly lower than 0.5 (0.25), whereas for the Cx. decens species group (0.56), the difference was not significant. Interpretation of the latter result was complicated by the significant effect of CO2 levels on the index. Species caught in low numbers but whose trap distribution showed a bias towards the human-baited trap were An. funestus (total numbers in the human-baited trap to the calf-baited trap = 9:0), Mansonia africana (17: 1), Aedes dalzieli (22:4), and Ae. hirsutus (13:1); species showing bias towards the calf-baited trap were An. rufipes (0:11), Cx. duttoni (0:17), and Cx. nebulosus (2:35). Mansonia uniformis was the only species distributed randomly between the two traps. Molecular identification of the An. gambiae s.l. samples revealed a marked difference in trap distribution: for the human-baited trap the ratio was 52% An. arabiensis to 48% An. gambiae s.s.; for the calf-baited trap, it was 92% An. arabiensis to 8% An. gambiae s.s.

Animals↗
PubMed1998

Re-emergence of yellow fever in Senegal in 1995.

An outbreak of yellow fever (YF) occurred in the central part of Senegal during October 1995. Thirty-one probable cases were detected and 79 cases were confirmed either by IgM ELISA or by virus isolation (30 strains isolated). The case fatality rate was 18.9%. Incidence of the infection was evaluated by a serosurvey in the area. Males 10-29 years old belonging to the Peul ethnic group were more affected. Moreover, 28 YF virus strains were isolated from mosquitoes and larvae pools and vertical transmission of YF virus by Aedes aegypti was also demonstrated for the first time in the field. This outbreak occurred after the major amplification of the wild cycle of YF virus in 1993 in West Africa. This epidemic represented a typical example of intermediate transmission of YF: both humans and wild vertebrates are involved in the virus cycle through wild mosquitoes with semidomestic habits, mainly Ae. furcifer, Ae. luteocephalus, and domestic vector Ae. aegypti. It was controlled by a prompt immunization campaign. The impact of inclusion of YF vaccine in the Expanded Program of Immunization, which has been conducted in Senegal for eight years, is discussed.

Adolescent↗
PubMed1998

Gametocyte infectivity by direct mosquito feeds in an area of seasonal malaria transmission: implications for Bancoumana, Mali as a transmission-blocking vaccine site.

Infectivity of gametocytemic volunteers living in Bancoumana, a village 60 km from Bamako, Mali, was determined by direct feeds of laboratory-reared Anopheles gambiae s. l. Gametocytemic adolescents (10-18 years old) were as infectious to mosquitoes as younger volunteers and appear to be a more suitable population for testing transmission-blocking efficacy as compared with adults (> 18 years old). To begin to validate the membrane-feeding assay, sera collected from these same volunteers were subjected to a standard membrane-feeding assay. The data suggest that areas with intense but seasonal transmission might be feasible sites for testing transmission-blocking vaccines because of the high gametocytemic rates, high mosquito infectivity rates, and lack of pre-existing humoral-mediated transmission-blocking activity. The differences observed between field-based direct mosquito feeds and laboratory-based membrane feeding assays suggests that caution be used in interpreting Phase I study results in which laboratory-based membrane-feeding assays are used as a surrogate for vaccine efficacy.

Adolescent↗
PubMed1997

Increasing resistance of Neisseria gonorrhoeae in west and central Africa. Consequence on therapy of gonococcal infection.

BACKGROUND AND OBJECTIVES: Antimicrobial resistant strains of Neisseria gonorrhoeae have spread with remarkable rapidity in many African countries. Chromosomal resistance to penicillin, tetracycline, and thiamphenicol is frequent now, and reported prevalences of penicillinase-producing N. gonorrhoeae isolates vary between 15% and 80%. Plasmid-mediated tetracycline-resistant N. gonorrhoeae isolates have been observed in several African countries. GOALS: To characterize gonococcal isolates from three sites in West and Central Africa, to determine antimicrobial susceptibility patterns, to document the spread of plasmid-mediated resistance to penicillin and tetracycline in these three sites, and to discuss the consequences of rising antimicrobial resistance on the management of gonococcal infection in Africa. STUDY DESIGN: Over time, a total of 2,288 gonococcal isolates were obtained from Abidjan, Ivory Coast (1992-1993, n = 251), from Kigali, Rwanda (1988-1993, n = 952), and from Kinshasa, Zaire (1988-1990, n = 1,085). The isolates were characterized by auxotyping and serotyping. Plasmid-mediated resistance to penicillin and to tetracycline was determined. Antimicrobial susceptibility testing to ceftriaxone, ciprofloxacin, penicillin, spectinomycin, tetracycline, and thiamphenicol was performed with an agar dilution method. RESULTS: The prevalence of penicillinase-producing N. gonorrhoeae increased significantly over time from 44% to 57% in Kigali and remained stable at a high level in Abidjan (73%) and in Kinshasa (67%). The frequency of tetracycline-resistant N. gonorrhoeae increased significantly during the observation periods in all three sites: from 20% to 65% in Abidjan, from 0% to 64% in Kigali, and from 14% to 41% in Kinshasa. Chromosomal resistance to penicillin was common in Kigali and Kinshasa, and chromosomal resistance to tetracycline and thiamphenicol was frequent in all three sites. All gonococcal isolates were susceptible to ceftriaxone, ciprofloxacin, and spectinomycin. Prototrophic and proline requiring strains were predominant, and IA-6 was the most common serovar in the three sites. IB-specific serovars were more common among penicillinase-producing N. gonorrhoeae and IA-specific serovars were more frequent among tetracycline-resistant N. gonorrhoeae, but there was no evidence for a clonal spread of resistant strains. CONCLUSIONS: This study illustrates the high frequency of resistant gonococci in Africa and shows that tetracycline-resistant N. gonorrhoeae have become highly endemic in different geographic areas of the continent. The use of effective drugs is essential to reduce gonorrhea transmission. Surveillance of temporal changes in antimicrobial resistance in gonococcal strain populations should be part of sexually transmitted diseases control programs.

Cote d'Ivoire↗
PubMed1996

Surveillance for yellow fever virus in eastern Senegal during 1993.

During the 1993 rainy season, 15,806 mosquitoes, including 14,304 Aedes ssp., were collected and tested for virus infection in 702 and 547 pools, respectively. Aedes furcifer (Edwards) was the most abundant species collected throughout the survey period. Yellow fever (YF) virus was detected in 187 pools: Ae. furcifer (123 isolates), Ae. taylori (Edwards) (41 isolates), and Ae. luteocephalus (Newstead) (23 isolates). A high prevalence of immunoglobulin (IgG) antibodies was found in human and simian populations. Results clearly indicated that increased sylvatic YF activity in eastern Senegal has the increased the risk of YF transmission among rural populations in West Africa. Our results showed that a minimal survey period may be effective in detecting the circulation of YF in the Kedougou area.

Aedes↗
PubMed1996

[Ngari virus (Bunyaviridae: Bunyavirus). First isolation from humans in Senegal, new mosquito vectors, its epidemiology].

Ngari virus (NRI) (Bunyaviridae, genus Bunyavirus) was isolated first from male Aedes simpsoni mosquitoes in Southeastern Senegal in 1979. Then, it was recovered from several mosquito species in Senegal, Burkina Faso, Central African Republic and Madagascar. A potential pathogenicity of NRI virus in humans was suspected when the virus was isolated from two patients in Dakar in October and November 1993. The large diversity of Culicidae vectors and feeding patterns showed a large heterogeneity of vertebrate hosts. The wide geographical distribution of NRI virus in different bioclimatic areas indicated an important adaptability of the virus. Ngari virus epidemiology will need further investigations in order to approach the real pathogenicity of such emerging virus.

Animals↗
PubMed1994

Neonatal thrombocytopenia in HLA-DR, -DQ, -DP-typed mother due to rare anti-HPA-1b (PLA2) (Zwb) fetomaternal immunization.

A new case of rare neonatal alloimmune thrombocytopenia, due to an IgG anti-HPA-1b in a mother HPA-1 (a+, b-), was diagnosed using monoclonal antibody-specific immobilization of platelet antigens. Clinically, it was similar to the 2 previously reported observations and confirmed that, in this particular case of anti-HPA-1b, the treatment with random platelet pools may be as effective as selected single-donor platelet units when maternal platelets are unusable. The HLA-DR, -DQ, -DP genotypes of the family were obtained by PCR-SSO. The mother's typing, compared to the HLA-DR of the 6 similar cases reported in Europe, suggests that a combined effect of two rare HLA haplotypes might enhance this immunization.

Adult↗
PubMed1993

Analysis of the human antibody response to thrombospondin-related anonymous protein of Plasmodium falciparum.

Thrombospondin-related anonymous protein (TRAP) of the malaria parasite Plasmodium falciparum shares two sequence motifs with other proteins which possess adhesive properties. Recently, findings indicate that TRAP is an antigen which contributes to antisporozoite immunity. We have cloned and expressed the TRAP coding sequences in Escherichia coli to investigate the human humoral immune response against this protein in a region of malaria endemicity of West Africa characterized by a seasonal transmission. Our results show that antibodies against TRAP are present in infected individuals. The anti-TRAP antibodies were analyzed in both a longitudinal and a prospective study. The longitudinal analysis shows seasonal fluctuations of the levels of specific antibodies as well as age-dependent quantitative differences. The immune response is long-lived in most of the adults and some of the older children but short-lived in young children. More importantly, the prospective analysis suggests that the presence of anti-TRAP antibodies in older children before the beginning of malaria transmission correlates with the subsequent control of parasite densities.

Adolescent↗