First detection of the malaria vector Anopheles arabiensis in Côte d'Ivoire: urbanization in question.

BACKGROUND: Previous studies have revealed high malaria transmission in Bouaké, Côte d'Ivoire. The sociopolitical crisis in the country and the resulting environmental changes have raised the need to update existing knowledge on mosquito vector species and malaria transmission. METHODS: Adult mosquitoes were caught using the human landing catch (HLC) sampling method in Bouaké. They were collected in six districts representative of the diversity in urban landscapes. Sampling points were selected along the water network crossing the city and monitored from 2020 to 2021 to detect the presence of anopheline larvae. PCR techniques were used to ascertain the species of the Anopheles gambiae complex, Plasmodium falciparum sporozoite infection in a subset of Anopheles vectors, and insecticide resistance mechanisms in Anopheles arabiensis only. RESULTS: A total of 4599 Anopheles mosquitoes were collected and then identified. Anopheles gambiae sensu lato (s.l.) made up the majority of the whole collection (99%) while Anopheles funestus (0.7%), Anopheles ziemanni (0.2%), Anopheles pharoensis (0.2%) represented the remaining proportion of collection. Among the Anopheles gambiae complex, three species were identified namely An. gambiae sensu stricto (45.9%), Anopheles coluzzii (52.2%), and Anopheles arabiensis (1.9%). The first two species had already been collected in Bouaké, however this is the first time that An. arabiensis is reported in Côte d'Ivoire. Anopheles arabiensis was also collected during the larval surveys in a similar proportion (1.1%) in the same areas as the adults. CONCLUSIONS: This study detected the presence of An. arabiensis for the first time in Côte d'Ivoire. This species was found quite far from its usual geographic area and its expansion could be linked to the urbanization process. Although no An. arabiensis was found to be infected by Plasmodium sp., its role in malaria transmission in Bouaké has to be explored, particularly since its exophagic behaviour raises the issue of control measures and the use of insecticide-impregnated nets. The spread of this species in Côte d'Ivoire should be assessed through further research in additional towns in the country.

Lessons learned for surveillance system strengthening through capacity building and partnership engagement in post-Ebola Guinea, 2015-2019.

The 2014-2016 Ebola outbreak in Guinea revealed systematic weaknesses in the existing disease surveillance system, which contributed to delayed detection, underreporting of cases, widespread transmission in Guinea and cross-border transmission to neighboring Sierra Leone and Liberia, leading to the largest Ebola epidemic ever recorded. Efforts to understand the epidemic's scale and distribution were hindered by problems with data completeness, accuracy, and reliability. In 2017, recognizing the importance and usefulness of surveillance data in making evidence-based decisions for the control of epidemic-prone diseases, the Guinean Ministry of Health (MoH) included surveillance strengthening as a priority activity in their post-Ebola transition plan and requested the support of partners to attain its objectives. The U.S. Centers for Disease Control and Prevention (US CDC) and four of its implementing partners-International Medical Corps, the International Organization for Migration, RTI International, and the World Health Organization-worked in collaboration with the Government of Guinea to strengthen the country's surveillance capacity, in alignment with the Global Health Security Agenda and International Health Regulations 2005 objectives for surveillance and reporting. This paper describes the main surveillance activities supported by US CDC and its partners between 2015 and 2019 and provides information on the strategies used and the impact of activities. It also discusses lessons learned for building sustainable capacity and infrastructure for disease surveillance and reporting in similar resource-limited settings.

A Sporadic and Lethal Lassa Fever Case in Forest Guinea, 2019.

Lassa fever is a rodent-borne disease caused by Lassa virus (LASV). It causes fever, dizziness, vertigo, fatigue, coughing, diarrhea, internal bleeding and facial edema. The disease has been known in Guinea since 1960 but only anectodical acute cases have been reported to date. In January 2019, a 35-year-old man, a wood merchant from Kissidougou, Forest Guinea, presented himself at several health centers with persistent fever, frequent vomiting and joint pain. He was repeatedly treated for severe malaria, and died three weeks later in Mamou regional hospital. Differential diagnosis identified LASV as the cause of death. No secondary cases were reported. The complete LASV genome was obtained using next-generation sequencing. Phylogenetic analysis showed that this strain, namely the Kissidougou strain, belongs to the clade IV circulating in Guinea and Sierra Leone, and is thought to have emerged some 150 years ago. Due to the similarity of symptoms with malaria, Lassa fever is still a disease that is difficult to recognize and that may remain undiagnosed in health centers in Guinea.

Vectorial Transmission of Malaria in Major Districts of Côte d'Ivoire.

To better understand the influence of periodic mass distribution of Long-Lasting Insecticidal Nets (LLINs) on malaria transmission, a 1-yr entomological survey was conducted in three major districts of Côte d'Ivoire. Mosquitoes were sampled by Human Landing Catches (HLC) in urban and rural areas of San Pedro and Abidjan (coastal), and in Yamoussoukro (central). Mosquitoes were identified morphologically and by molecular methods. The Plasmodium falciparum circumsporozoite (CSP) indices were measured by ELISA, and the Entomological Inoculation Rates (EIR) were calculated for each species and area. Anopheles gambiae s.l. Giles (Diptera: Culicidae) and Anopheles nili Theobald (Diptera: Culicidae) were identified in coastal districts, while An. gambiae s.l. and Anopheles funestus Giles (Diptera: Culicidae) were reported in the central district. In urban areas, malaria vectors showed a low aggressiveness (<10 bites per person per night), except in Yamoussoukro, where up to 18.9 b/p/n were recorded. The annual EIR was higher in the central urban area (138.7 infected bites per person per year) than in coastal ones (10-62 ib/p/n). In rural areas, malaria vectors were highly aggressive with an average 13 b/p/n for An. gambiae s.l, 21.2 b/p/n for An. nili and 12 b/p/n for An. funestus. The annual EIR ranged between 94.9 and 193.4 infected bites per person per year. This work indicates that, despite repeated mass distribution of LLINs, malaria transmission remains high and heterogeneous across Côte d'Ivoire. Malaria transmission was lower in coastal urban areas than in the central one, and remains high rural areas where two additional Anopheles vectors are involved in malaria transmission.

Emergence of Vaccine-Derived Polioviruses during Ebola Virus Disease Outbreak, Guinea, 2014-2015.

During the 2014-2015 outbreak of Ebola virus disease in Guinea, 13 type 2 circulating vaccine-derived polioviruses (cVDPVs) were isolated from 6 polio patients and 7 healthy contacts. To clarify the genetic properties of cVDPVs and their emergence, we combined epidemiologic and virologic data for polio cases in Guinea. Deviation of public health resources to the Ebola outbreak disrupted polio vaccination programs and surveillance activities, which fueled the spread of neurovirulent VDPVs in an area of low vaccination coverage and immunity. Genetic properties of cVDPVs were consistent with their capacity to cause paralytic disease in humans and capacity for sustained person-to-person transmission. Circulation ceased when coverage of oral polio vaccine increased. A polio outbreak in the context of the Ebola virus disease outbreak highlights the need to consider risks for polio emergence and spread during complex emergencies and urges awareness of the challenges in polio surveillance, vaccination, and diagnosis.

Prevalence and awareness of diabetes in Guinea: findings from a WHO STEPS

Aims: The aim of the present study was to determine the prevalence of diabetes, and to assess its awareness and related risk factors among adult Guineans.Methods: A population-based cross-sectional survey was conducted on 1 100 adults (46.6% women) aged 35­64 years from Lower Guinea, during September to December 2009, using the WHO STEPwise approach of surveillance of chronic disease risk factors. Data were collected in three steps: demographic and behavioural risk factors, blood pressure and anthropometric measurements, and fasting blood cholesterol and glucose testing. A multi-stage cluster sample design was applied to generate nationwide representative data.Results: The mean age of all participants was 47.3 years (SD 8.8), similarly in Conakry, rural Lower Guinea and urban Lower Guinea. The prevalence of diabetes was 5.7% (95% CI 4.0­8.1). Among participants with diabetes, only 44.0% were aware of their status. In multivariable logistic regression analysis, determinants of diabetes prevalence were urban residency, male sex, age group 45­64 years, increased waist circumference, hypertension and hypercholesterolemia. Male sex, rural residency, age group 45­54 years, no formal education, waist circumference, hypertension and hypercholesterolemia were independent predictors of screen-detected diabetes.Conclusion: The present study found a high prevalence and low awareness of diabetes, suggesting the need for appropriate actions to strengthen primary healthcare approaches towards non-communicable diseases in Guinea

Ebola virus disease in West Africa--the first 9 months of the epidemic and forward projections.

BACKGROUND: On March 23, 2014, the World Health Organization (WHO) was notified of an outbreak of Ebola virus disease (EVD) in Guinea. On August 8, the WHO declared the epidemic to be a "public health emergency of international concern." METHODS: By September 14, 2014, a total of 4507 probable and confirmed cases, including 2296 deaths from EVD (Zaire species) had been reported from five countries in West Africa--Guinea, Liberia, Nigeria, Senegal, and Sierra Leone. We analyzed a detailed subset of data on 3343 confirmed and 667 probable Ebola cases collected in Guinea, Liberia, Nigeria, and Sierra Leone as of September 14. RESULTS: The majority of patients are 15 to 44 years of age (49.9% male), and we estimate that the case fatality rate is 70.8% (95% confidence interval [CI], 69 to 73) among persons with known clinical outcome of infection. The course of infection, including signs and symptoms, incubation period (11.4 days), and serial interval (15.3 days), is similar to that reported in previous outbreaks of EVD. On the basis of the initial periods of exponential growth, the estimated basic reproduction numbers (R0 ) are 1.71 (95% CI, 1.44 to 2.01) for Guinea, 1.83 (95% CI, 1.72 to 1.94) for Liberia, and 2.02 (95% CI, 1.79 to 2.26) for Sierra Leone. The estimated current reproduction numbers (R) are 1.81 (95% CI, 1.60 to 2.03) for Guinea, 1.51 (95% CI, 1.41 to 1.60) for Liberia, and 1.38 (95% CI, 1.27 to 1.51) for Sierra Leone; the corresponding doubling times are 15.7 days (95% CI, 12.9 to 20.3) for Guinea, 23.6 days (95% CI, 20.2 to 28.2) for Liberia, and 30.2 days (95% CI, 23.6 to 42.3) for Sierra Leone. Assuming no change in the control measures for this epidemic, by November 2, 2014, the cumulative reported numbers of confirmed and probable cases are predicted to be 5740 in Guinea, 9890 in Liberia, and 5000 in Sierra Leone, exceeding 20,000 in total. CONCLUSIONS: These data indicate that without drastic improvements in control measures, the numbers of cases of and deaths from EVD are expected to continue increasing from hundreds to thousands per week in the coming months.

Transmission of malaria in relation to distribution and coverage of long-lasting insecticidal nets in central Côte d'Ivoire.

BACKGROUND: The use of long-lasting insecticidal nets (LLINs) is an effective malaria control strategy. However, there are challenges to achieve high coverage, such as distribution sustainability, and coverage keep-up. This study assessed the effect of LLINs coverage and contextual factors on entomological indicators of malaria in rural Côte d'Ivoire. METHODS: The study was carried out between July 2009 and May 2012 in three villages (Bozi, N'Dakonankro and Yoho) of central Côte d'Ivoire. In Bozi and Yoho, LLINs were distributed free of charge by the national malaria control programme in 2008. In Bozi, an additional distribution was carried out in May 2011. No specific interventions were done in N'Dakonankro. Entomological surveys were conducted in July 2009 and July 2010 (baseline), and in August and November 2011 and in February 2012. Frequency of circumsporozoite protein was determined using an enzyme-linked immunosorbent assay. Regression models were employed to assess the impact of LLINs and changing patterns of irrigated rice farming on entomological parameters, and to determine associations with LLINs coverage and other contextual factors. RESULTS: In Bozi, high proportion of LLIN usage was observed (95-100%). After six months, 95% of LLINs were washed at least once and 79% were washed up to three times within one year. Anopheles gambiae was the predominant malaria vector (66.6% of all mosquitoes caught). From 2009 to 2012, in N'Dakonankro, the mean annual entomological inoculation rate (EIR) increased significantly from 116.8 infectious bites/human/year (ib/h/y) to 408.8 ib/h/y, while in the intervention villages, the EIR decreased significantly from 514.6 ib/h/y to 62.0 ib/h/y (Bozi) and from 83.9 ib/h/y to 25.5 ib/h/y (Yoho). The risk of an infectious bite over the three-year period was significantly lower in the intervention villages compared to the control village (p<0.001). CONCLUSION: High coverage and sensitization of households to use LLINs through regular visits (particularly in Bozi) and abandoning irrigated rice farming (in Yoho) resulted in highly significant reductions of EIR. The national malaria control programme should consider household sensitization and education campaigns and other contextual factors to maximize the benefit of LLINs.

Tinea capitis in schoolchildren in southern Ivory Coast.

OBJECTIVES: Fungal infections of the scalp commonly affect the pediatric population. These infections are caused by dermatophytes that are able to invade the keratinized structures of skin, hair, and nails. This study aimed to analyze the epidemiology of fungal scalp infections in southern Ivory Coast during 2008-2009. METHODS: From October 2008 to July 2009, 17,745 children ranging in age from 4-16 years, attending urban and rural primary schools in seven towns in Ivory Coast, were examined clinically for tinea capitis. Hair stumps and scales were collected from children who showed symptoms suggestive of scalp ringworm. Samples were exposed to direct microscopic examination using 30% potassium hydroxide solution and cultivation on Sabouraud's dextrose agar with or without actidione. RESULTS: Of the 17,745 children who were clinically examined, a total of 2645 exhibited symptoms suggestive of scalp ringworm. Positive cultures for fungi were found in 2458, yielding an overall prevalence of tinea capitis of 13.9%. The majority of infections occurred in males (74.0%). The most commonly affected age group involved children ranging from 9-12 years (n = 1335, 54.3%), followed by those in the range of 4-8 years (n = 936, 38.1%). Trichophyton soudanense, Microsporum langeronii, and Trichophyton mentagrophytes were the most prevalent etiologic agents (56.7%, 21.4% and 19.7%, respectively). Other species were occasionally isolated, including Trichophyton violaceum (1.4%) and Trichophyton rubrum (0.8%). CONCLUSIONS: Epidemiological surveys are an essential tool for developing strategies for infection control.

Phenetic and genetic structure of tsetse fly populations (Glossina palpalis palpalis) in southern Ivory Coast.

BACKGROUND: Sleeping sickness, transmitted by G. p. palpalis, is known to be present in the Ivory Coast. G. p. palpalis has recently been reported to occur in several places within the town of Abidjan, including: (i) the Banco forest, (ii) the Abobo Adjamé University campus and (iii) the zoological park. Could these three places be treated sequentially, as separate tsetse populations, or should they be taken as one area comprising a single, panmictic population? METHODS: The amount of gene flow between these places provides strategic information for vector control. It was estimated by the use of both microsatellite DNA and morphometric markers. The idea was to assess the interest of the faster and much less expensive morphometric approach in providing relevant information about population structure. Thus, to detect possible lack of insect exchange between these neighbouring areas of Abidjan, we used both genetic (microsatellite DNA) and phenetic (geometric morphometrics) markers on the same specimens.Using these same markers, we also compared these samples with specimens from a more distant area of south Ivory Coast, the region of Aniassué (186 km north from Abidjan). RESULTS: Neither genetic nor phenetic markers detected significant differentiation between the three Abidjan G. p. palpalis samples. Thus, the null hypothesis of a single panmictic population within the city of Abidjan could not be rejected, suggesting the control strategy should not consider them separately. The markers were also in agreement when comparing G. p. palpalis from Abidjan with those of Aniassué, showing significant divergence between the two sites. CONCLUSIONS: Both markers suggested that a successful control of tsetse in Abidjan would require the three Abidjan sites to be considered together, either by deploying control measures simultaneously in all three sites, or by a continuous progression of interventions following for instance the "rolling carpet" principle. To compare the geometry of wing venation of tsetse flies is a cheap and fast technique. Agreement with the microsatellite approach highlights its potential for rapid assessment of population structure.

Update on resistance status of Anopheles gambiae s.s. to conventional insecticides at a previous WHOPES field site, "Yaokoffikro", 6 years after the political crisis in Côte d'Ivoire.

BACKGROUND: At Yaokoffikro field site near Bouaké, in central Côte d'Ivoire, a group of experimental huts built in 1996 served over many years for the evaluation of insecticides against highly resistant mosquitoes. Breeding sites of mosquitoes and selection pressure in the area were maintained by local farming practices until a war broke out in September 2002. Six years after the crisis, we conducted bioassays and biochemical analysis to update the resistance status of Anopheles gambiae s.s. populations and detect other potential mechanisms of resistance that might have evolved. METHODS: An. gambiae s.s. larvae from Yaokoffikro were collected in breeding sites and reared to adults. Resistance status of this population to insecticides was assessed using WHO bioassay test kits for adult mosquitoes with seven insecticides: two pyrethroids, a pseudo-pyrethroid, an organochloride, two carbamates and an organophosphate.Molecular and biochemical assays were carried out to identify the L1014F kdr and ace-1R alleles in individual mosquitoes and to detect potential increase in mixed function oxidases (MFO), non-specific esterases (NSE) and glutathione S-transferases (GST) activity. RESULTS: High pyrethroids, DDT and carbamate resistance was confirmed in An. gambiae s.s. populations from Yaokoffikro. Mortality rates were less than 70% with pyrethroids and etofenprox, 12% with DDT, and less than 22% with the carbamates. Tolerance to fenitrothion was observed, with 95% mortality after 24 h.PCR analysis of samples from the site showed high allelic frequency of the L1014F kdr (0.94) and the ace-1R (0.50) as before the crisis. In addition, increased activity of NSE, GST and to a lesser extent MFO was found relative to the reference strain Kisumu. This was the first report detecting enhanced activity of these enzymes in An. gambiae s.s from Yaokoffikro, which could have serious implications in detoxification of insecticides. Their specific roles in resistance should be investigated using additional tools. CONCLUSION: The insecticide resistance profile at Yaokoffikro appears multifactorial. The site presents a unique opportunity to evaluate its impact on the protective efficacy of insecticidal products as well as new tools to manage these complex mechanisms. It calls for innovative research on the behaviour of the local vector, its biology and genetics that drive resistance.

Comparative study of the efficacy and tolerability of dihydroartemisinin-piperaquine-trimethoprim versus artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in Cameroon, Ivory Coast and Senegal.

BACKGROUND: The ACT recommended by WHO is very effective and well-tolerated. However, these combinations need to be administered for three days, which may limit adherence to treatment.The combination of dihydroartemisinin-piperaquine phosphate-trimethoprim (Artecom®, Odypharm Ltd), which involves treatment over two days, appears to be a good alternative, particularly in malaria-endemic areas. This study intends to compare the efficacy and tolerability of the combination dihydroartemisinin-piperaquine phosphate-trimethoprim (DPT) versus artemether-lumefantrine (AL) in the treatment of uncomplicated Plasmodium falciparum malaria in Cameroon, Ivory Coast and Senegal. METHODS: This was a randomized, controlled, open-label clinical trial with a 28-day follow-up period comparing DPT to AL as the reference drug. The study involved patients of at least two years of age, suffering from acute, uncomplicated Plasmodium falciparum malaria with fever. The WHO 2003 protocol was used. RESULTS: A total of 418 patients were included in the study and divided into two treatment groups: 212 in the DPT group and 206 in the AL group. The data analysis involved the 403 subjects who correctly followed the protocol (per protocol analysis), i.e. 206 (51.1%) in the DPT group and 197 (48.9%) in the AL group. The recovery rate at D14 was 100% in both treatment groups. The recovery rate at D28 was 99% in the DPT and AL groups before and after PCR results with one-sided 97.5% Confidence Interval of the rates difference > -1.90%. More than 96% of patients who received DPT were apyrexial 48 hours after treatment compared to 83.5% in the AL group (p < 0.001). More than 95% of the people in the DPT group had a parasite clearance time of 48 hours or less compared to approximately 90% in the AL group (p = 0.023). Both drugs were well tolerated. No serious adverse events were reported during the follow-up period. All of the adverse events observed were minor and did not result in the treatment being stopped in either treatment group. The main minor adverse events reported were vomiting, abdominal pain and pruritus. CONCLUSION: The overall efficacy and tolerability of DPT are similar to those of AL. The ease of taking DPT and its short treatment course (two days) may help to improve adherence to treatment. Taken together, these findings make this medicinal product a treatment of choice for the effective management of malaria in Africa.

Multicentric assessment of the efficacy and tolerability of dihydroartemisinin-piperaquine compared to artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in sub-Saharan Africa.

BACKGROUND: The choice of appropriate artemisinin-based combination therapy depends on several factors (cost, efficacy, safety, reinfection rate and simplicity of administration). To assess whether the combination dihydroartemisinin-piperaquine (DP) could be an alternative to artemether-lumefantrine (AL), the efficacy and the tolerability of the two products for the treatment of uncomplicated falciparum malaria in sub-Saharan Africa have been compared. METHODS: A multicentric open randomized controlled clinical trial of three-day treatment of DP against AL for the treatment of two parallel groups of patients aged two years and above and suffering from uncomplicated falciparum malaria was carried out in Cameroon, Côte d'Ivoire and Senegal. Within each group, patients were randomly assigned supervised treatment. DP was given once a day for three days and AL twice a day for three days. Follow-up visits were performed on day 1 to 4 and on day 7, 14, 21, 28 to evaluate clinical and parasitological results. The primary endpoint was the recovery rate by day 28. RESULTS: Of 384 patients enrolled, 197 were assigned DP and 187 AL. The recovery rates adjusted by genotyping, 99.5% in the DP group and 98.9% in the AL group, were not statistically different (p=0.538). No Early Therapeutic Failure (ETF) was observed. At day 28, two patients in the DP group and five in AL group had recurrent parasitaemia with Plasmodium falciparum. In the DP group, after PCR genotyping, one of the two recurrences was classified as a new infection and the other as recrudescence. In AL group, two recurrences were classified after correction by PCR as recrudescence. All cases of recrudescence were classified as Late Parasitological Failure (LPF). In each group, a rapid recovery from fever and parasitaemia was noticed. More than 90% of patients did no longer present fever or parasitaemia 48 hours after treatment. Both drugs were well tolerated. Indeed, no serious adverse events were reported during the follow-up period. Most of the adverse events which developed were moderate and did not result in the treatment being stopped in either treatment group. CONCLUSIONS: Dihydroartemisinin-piperaquine was as effective and well-tolerated as artemether-lumefantrine in the treatment of uncomplicated falciparum malaria. In addition, dihydroartemisinin-piperaquine, a single daily dose, could be an advantage over artemether-lumefantrine in Africa because of better treatment observance.

Coverage of intermittent prevention treatment with sulphadoxine-pyrimethamine among pregnant women and congenital malaria in Côte d'Ivoire.

BACKGROUND: The World Health Organization (WHO) recommends using insecticide-treated mosquito nets (ITNs) and intermittent preventive treatment with sulphadoxine-pyrimethamine (IPT-SP) to prevent malaria in sub-Saharan Africa. Data on IPT-SP coverage and factors associated with placental malaria parasitaemia and low birth weight (LBW) are scarce in Côte d'Ivoire. METHODS: A multicentre, cross-sectional survey was conducted in Côte d'Ivoire from March to September 2008 at six urban and semi-urban antenatal clinics. Standardized forms were used to collect the demographic information and medical histories of women and their offspring. IPT-SP coverage (≥2 doses) as well as placental and congenital malaria prevalence parasitaemia were estimated. Regression logistics were used to study factors associated with placental malaria and LBW (birth weight of alive babies < 2,500 grams). RESULTS: Overall, 2,044 women with a median age of 24 years were included in this study. Among them 1017 (49.8%) received ≥2 doses of IPT-SP and 694 (34.0%) received one dose. A total of 99 mothers (4.8%) had placental malaria, and of them, four cases of congenital malaria were diagnosed. Factors that protected from maternal placental malaria parasitaemia were the use of one dose (adjusted odds ratio (aOR), 0.32; 95%CI: 0.19-0.55) or ≥2 doses IPT-SP (aOR: 0.18; 95%CI: 0.10-0.32); the use of ITNs (aOR: 0.47; 95%CI: 0.27-0.82). LBW was associated with primigravidity and placental malaria parasitaemia. CONCLUSION: IPT-SP decreases the rate of placental malaria parasitaemia and has a strong dose effect. Despite relatively successful IPT-SP coverage in Côte d'Ivoire, substantial commitments from national authorities are urgently required for such public health campaigns. Strategies, such as providing IPT-SP free of charge and directly observing treatment, should be implemented to increase the use of IPT-SP as well as other prophylactic methods.

Distribution of ace-1R and resistance to carbamates and organophosphates in Anopheles gambiae s.s. populations from Côte d'Ivoire.

BACKGROUND: The spread of pyrethroid resistance in Anopheles gambiae s.s. is a critical issue for malaria vector control based on the use of insecticide-treated nets. Carbamates and organophosphates insecticides are regarded as alternatives or supplements to pyrethroids used in nets treatment. It is, therefore, essential to investigate on the susceptibility of pyrethroid resistant populations of An. gambiae s.s. to these alternative products. METHODS: In September 2004, a cross sectional survey was conducted in six localities in Côte d'Ivoire: Toumbokro, Yamoussoukro, Toumodi in the Southern Guinea savannah, Tiassalé in semi-deciduous forest, then Nieky and Abidjan in evergreen forest area. An. gambiae populations from these localities were previously reported to be highly resistant to pyrethroids insecticides. Anopheline larvae were collected from the field and reared to adults. Resistance/susceptibility to carbamates (0.4% carbosulfan, 0.1% propoxur) and organophosphates (0.4% chlorpyrifos-methyl, 1% fenitrothion) was assessed using WHO bioassay test kits for adult mosquitoes. Then, PCR assays were run to determine the molecular forms (M) and (S), as well as phenotypes for insensitive acetylcholinesterase (AChE1) due to G119S mutation. RESULTS: Bioassays showed carbamates (carbosulfan and propoxur) resistance in all tested populations of An. gambiae s.s. In addition, two out of the six tested populations (Toumodi and Tiassalé) were also resistant to organophosphates (mortality rates ranged from 29.5% to 93.3%). The M-form was predominant in tested samples (91.8%). M and S molecular forms were sympatric at two localities but no M/S hybrids were detected. The highest proportion of S-form (7.9% of An. gambiae identified) was in sample from Toumbokro, in the southern Guinea savannah. The G119S mutation was found in both M and S molecular forms with frequency from 30.9 to 35.2%. CONCLUSION: This study revealed a wide distribution of insensitive acetylcholinesterase due to the G119S mutation in both M and S molecular forms of the populations of An. gambiae s.s. tested. The low cross-resistance between carbamates and organophosphates highly suggests involvement of other resistance mechanisms such as metabolic detoxification or F290V mutation.

[In vitro susceptibility of P. falciparum isolates from Abidjan (Côte d'Ivoire) to quinine, artesunate and chloroquine]. / Sensibilité in vitro de P. falciparum à la quinine, l'artésunate et la chloroquine à Abidjan (Côte d'Ivoire).

INTRODUCTION: Malaria is still a major public health problem in Côte d'Ivoire. Both treatment and control there are hampered by the spread of resistance to common antimalarial drugs, especially in the south where multidrug-resistant malaria is highly prevalent. Recent treatment guidelines require in vitro tests and the adaptation of drug policies according to local resistance rates. In addition to performing clinical assays in the field, we sought to establish a national map of drug resistance by using in vitro tests with clinical surveys. These make it possible to detect changes in susceptibility and are expected to prevent the emergence of resistance against the most recently introduced combined therapy. MATERIALS AND METHODS: Isolates of Plasmodium falciparum. Isolates of P. falciparum were collected from symptomatic adults and paediatric patients seen at Anonkoua-Kouté Hospital or at the Pasteur Institute of Côte d'Ivoire. Venous blood samples were collected in heparinized vacutainer tubes (Becton Dickinson, Rutherford, NJ, USA). Giemsa-stained thin and thick blood smears were examined for infection by P. falciparum and parasite density was determined. Only blood samples with a parasite density>4,000 parasites/microL of blood were used. When parasite density exceeded 10,000 parasites/microL, freshly washed uninfected red blood cells were added to adjust parasite density to this level. All drug susceptibility assays were performed within 48 h after blood samples were taken. DRUGS: Stock solutions of chloroquine, quinine and artesunate were prepared in methanol. The final concentration of methanol did not exceed 0.05%. The concentrations of the solutions tested ranged from 12.5 to 1,600 nM for chloroquine, 25 to 2 400 nM for quinine and 0.12 to 100 nM for artesunate. In vitro assays The in vitro drug sensitivity of the Ivorian isolates was assessed with a standard 48-h isotope test. Briefly, fresh blood samples were washed three times with RPMI 1640 medium (GibcoTM, Invitrogen Corporation, France) and centrifuged (1,500xg, 5 minutes). The parasites were then tested directly without culture adaptation. If parasitemia > 0.5%, fresh uninfected erythrocytes were added to adjust it to 0.3%. The infected erythrocytes (1.5% hematocrit, 0.1-1% parasitemia) were suspended in complete RPMI medium supplemented with 10% decomplemented human AB+ serum (Biomedia, France) and buffered with 25 mM/L HEPES and 25 mM/L NaHCO3. The mixture was distributed (200 microL per well) into 96-well test plates pre-coated with antimalarial agents. Each plate included two drug-free control wells and one control well without parasites. The culture plates were incubated for 48 h at 37 degrees C in a 5% CO2 atmosphere. [3H]Hypoxanthine (0.5 mCi/well; Amersham Biosciences, France) was used to assess parasite growth. Each isolate was tested once in duplicate in the microplates with serial drug dilutions. Drug response was quantified by monitoring [3H] hypoxanthine uptake in a Wallac MicroBeta Trilux counter (Perkin-Elmer, France). DATA ANALYSIS: The IC50 values (defined as the drug concentration that resulted in a level of 3H-hypoxanthine uptake 50% lower than that measured in the drug-free control wells) were determined by nonlinear regression analysis of the plot of the concentration logarithm against growth inhibition. Data were adapted to fit the log-probit model (Excel, Microsoft; Redmond, WA, USA). The threshold IC50 values for in vitro resistance to chloroquine, quinine and artésunate have previously been estimated to be >100 nM, >800 nM and >19.81 nM respectively. RESULTS: In all 23, 21 and 19 P. falciparum isolates grew satisfactorily in quinine, artésunate and chloroquine, respectively, and yielded interpretable results for these drugs. The geometric mean IC50 for quinine was 272.12 nM with values ranging from 2.08 to 660.28. For artésunate, the IC50 values ranged from 0.03 to 43.84 nM and the geometric mean was 7.49 nM. The IC50 values for chloroquine ranged from 17.71 to 359.19 nM, with a geometric mean for the 23 isolates of 93.72 nM. The proportions of resistant isolates were 26.10% for chloroquine (IC50>100 nM), 9.5% for artesunate (IC50>9.66 nM) and 0% for quinine. No multidrug-resistant isolates (resistant to more than three drugs) were found. CONCLUSION: The decreased susceptibility to artesunate of isolates collected in Abidjan justifies an improved surveillance program for drug resistance to malaria in Côte d'Ivoire.

Antiplasmodial activity and cytotoxicity of plants used in West African traditional medicine for the treatment of malaria.

Eighteen plants originating from Ivory Coast were selected by ethnobotanical survey as plants commonly used by traditional healers for the treatment of malaria. Extracts of these plants were tested on two strains of Plasmodium falciparum: FcM29-Cameroon (chloroquine-resistant strain) and a Nigerian chloroquine-sensitive strain. The powdered plants were used to prepare three kinds of extracts: by decoction in water, in ethanol (95%) and in pentane. A radioactive micromethod allowed the evaluation of the antiplasmodial in vitro activity of the extracts on P. falciparum. Concentrations inhibiting 50% of the parasite growth (IC50) ranged from 18 microg/ml to more than 500 microg/ml for aqueous and ethanol extracts and from 4.3 microg/ml to more than 500 microg/ml for pentane extracts. Cytotoxicity was estimated on A375 melanoma cells and a cytotoxicity/antiplasmodial index (CAR) was calculated for each extract, ranging from 1 to 10. The pentane extracts of Cola caricaefolia and Uvaria afzelii, which revealed the strongest antiplasmodial activity had CAR values of about 10.

Urban agricultural land use and characterization of mosquito larval habitats in a medium-sized town of Côte d'Ivoire.

Urban agriculture is common across Africa and contributes to the livelihoods of urban dwellers. Some crop systems create suitable mosquito breeding sites and thus might affect malaria transmission. The purpose of this study was to identify, map, and characterize potential mosquito breeding sites in agricultural land use zones in a medium-sized town of western Côte d'Ivoire and to assess risk factors for productive Anopheles breeding sites. Two surveys were carried out; one toward the end of the rainy season and the second one during the dry season. In all identified potential mosquito breeding sites, two experienced entomologists searched for the presence of Anopheles larvae and pupae with a standardized technique. Totals of 369 and 589 sites were found in the rainy and dry seasons, respectively, mainly in vegetable gardens and irrigated rice fields. Anopheles larvae were present in 50.7% and 42.4% of the sites investigated during the rainy and dry seasons, respectively. Typical Anopheles larval habitats were characterized by the presence of algae, the absence of floating vegetation, and the co-occurrence of Culex larvae. The highest Anopheles larval productivity was observed in rice paddies, agricultural trenches between vegetable patches, and irrigation wells. An indirect link could be established between the occurrence of productive Anopheles breeding sites and agricultural land use through specific man-made habitats, in particular agricultural trenches, irrigation wells, and rice paddies. Our findings have important bearings for the epidemiology and control of urban malaria in sub-Saharan Africa.

[Intestinal helminthiasis among school children: preliminary results of a prospective study in Agboville in Southern Côte d'Ivoire]. / Helminthiases intestinales chez les enfants d'âge scolaire: résultats préliminaires d'une étude prospective à Agboville dans le sud de la Côte d'Ivoire.

Intestinal helminthiasis affects the health and academic performance of children in developing countries. To highlight a few socio-economic factors that impact the presence and upholding of intestinal helminthiasis, a cohort study was performed from February to June 2001. This study took place in Agboville in Southern Côte d'Ivoire on 363 children, under the age of 15, regularly enrolled in school and selected by two-step clustered sampling. After the survey was completed, their stools were examined using 3 methods: direct exam, Kato's technique, and Graham's anal scotch-test. Infected students received an appropriate anti-helminthic treatment. After performing a test two weeks later, a new sample of 348 parasite-free children was made up and re-examined after three months, through the aforementioned techniques. In this sample, we assumed that students who were infested in the initial exam were "exposed", while those who were not infested in the first place were deemed to be "not exposed". The results showed that 135 students out of the 360 admitted for the first exam were infested; or a 37.5% of intestinal helminthiasis prevalence (IC95%=30.5-45). The prevalent parasite species were Necator americanus (15%), Trichuris trichiura (13.6%), Schistosoma mansoni (10%). Twenty-eight per cent of 135 infested students were infected by more than one parasite. After three months, the incidence rate of intestinal helminthiasis calculated out of the remaining 336 students was 7.7% (IC95%=4.4-13.1). The likelihood of re-infestation amounted to 3.4 (IC95%=1.5-7.3). The pattern of re-infestation rates according to socio-economic factors differed from that of infested prevalence. The prevalent parasites in re-infested patients were Trichuris trichiura (16.3%), Schistosoma mansoni (12.5%). All intestinal nematodes and Schistosoma mansoni were observed. The most frequent parasites species where those transmitted cutaneously. The high re-infestation rate suggests that intestinal helminthiasis in this region affects roughly the same children. These results show the necessity to continue our investigations in order to highlight essential hygienic factors in our long-term fight against intestinal helminthiasis.

[Antimalaria drug delivery in pharmacies in non-severe malaria treatment. A survey on the quality of the treatment: the case of Bouaké (Côte d'Ivoire)]. / Délivrance des antipaludiques en officine dans le traitement de l'accès palustre simple. Etude de la qualité du traitement: cas de la ville de Bouaké (Côte d'Ivoire).

In order to assess the action scheme of the National Program against Malaria, a study has been conducted in 25 pharmacies in Bouaké an area of high malaria transmission. The kind and quality of malaria treatments suggested by medical personnel, pharmacy sellers and used in automedication have been studied. The results proved that chloroquine is the molecule most delivered (25.7%) in private pharmacies. The parasitological diagnosis is scarcely requested by medical personnel. As in automedication, posological mistakes are relatively frequent with medical and pharmacy personnel (29.3%). The duration of the treatment is not specified in 14.2% of cases. Training and information actions must be reinforced for a better care of malaria.