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1.
Malar J ; 20(1): 32, 2021 Jan 09.
Artículo en Inglés | MEDLINE | ID: mdl-33422080

RESUMEN

BACKGROUND: Malaria remains highly endemic in Cameroon. The rapid emergence and spread of drug resistance was responsible for the change from monotherapies to artemisinin-based combinations. This systematic review and meta-analysis aimed to determine the prevalence and distribution of Plasmodium falciparum drug resistance markers within an evolving efficacy of anti-malarial drugs in Cameroon from January 1998 to August 2020. METHODS: The PRISMA-P and PRISMA statements were adopted in the inclusion of studies on single nucleotide polymorphisms (SNPs) of P. falciparum anti-malarial drug resistance genes (Pfcrt, Pfmdr1, Pfdhfr, Pfdhps, Pfatp6, Pfcytb and Pfk13). The heterogeneity of the included studies was evaluated using the Cochran's Q and I2 statistics. The random effects model was used as standard in the determination of heterogeneity between studies. RESULTS: Out of the 902 records screened, 48 studies were included in this aggregated meta-analysis of molecular data. A total of 18,706 SNPs of the anti-malarial drug resistance genes were genotyped from 47,382 samples which yielded a pooled prevalence of 35.4% (95% CI 29.1-42.3%). Between 1998 and 2020, there was significant decline (P < 0.0001 for all) in key mutants including Pfcrt 76 T (79.9%-43.0%), Pfmdr1 86Y (82.7%-30.5%), Pfdhfr 51I (72.2%-66.9%), Pfdhfr 59R (76.5%-67.8%), Pfdhfr 108 N (80.8%-67.6%). The only exception was Pfdhps 437G which increased over time (30.4%-46.9%, P < 0.0001) and Pfdhps 540E that remained largely unchanged (0.0%-0.4%, P = 0.201). Exploring mutant haplotypes, the study observed a significant increase in the prevalence of Pfcrt CVIET mixed quintuple haplotype from 57.1% in 1998 to 57.9% in 2020 (P < 0.0001). In addition, within the same study period, there was no significant change in the triple Pfdhfr IRN mutant haplotype (66.2% to 67.3%, P = 0.427). The Pfk13 amino acid polymorphisms associated with artemisinin resistance were not detected. CONCLUSIONS: This review reported an overall decline in the prevalence of P. falciparum gene mutations conferring resistance to 4-aminoquinolines and amino alcohols for a period over two decades. Resistance to artemisinins measured by the presence of SNPs in the Pfk13 gene does not seem to be a problem in Cameroon. Systematic review registration PROSPERO CRD42020162620.

2.
Malar J ; 19(1): 172, 2020 May 03.
Artículo en Inglés | MEDLINE | ID: mdl-32362282

RESUMEN

BACKGROUND: This study evaluated the effectiveness of improved housing on indoor residual mosquito density and exposure to infected Anophelines in Minkoameyos, a rural community in southern forested Cameroon. METHODS: Following the identification of housing factors affecting malaria prevalence in 2013, 218 houses were improved by screening the doors and windows, installing plywood ceilings on open eaves and closing holes on walls and doors. Monthly entomological surveys were conducted in a sample of 21 improved and 21 non-improved houses from November 2014 to October 2015. Mosquitoes sampled from night collections on human volunteers were identified morphologically and their parity status determined. Mosquito infectivity was verified through Plasmodium falciparum CSP ELISA and the average entomological inoculation rates determined. A Reduction Factor (RF), defined as the ratio of the values for mosquitoes collected outdoor to those collected indoor was calculated in improved houses (RFI) and non-improved houses (RFN). An Intervention Effect (IE = RFI/RFN) measured the true effect of the intervention. Chi square test was used to determine variable significance. The threshold for statistical significance was set at P < 0.05. RESULTS: A total of 1113 mosquitoes were collected comprising Anopheles sp (58.6%), Culex sp (36.4%), Aedes sp (2.5%), Mansonia sp (2.4%) and Coquillettidia sp (0.2%). Amongst the Anophelines were Anopheles gambiae sensu lato (s.l.) (95.2%), Anopheles funestus (2.9%), Anopheles ziemanni (0.2%), Anopheles brohieri (1.2%) and Anopheles paludis (0.5%). Anopheles gambiae sensu stricto (s.s.) was the only An. gambiae sibling species found. The intervention reduced the indoor Anopheles density by 1.8-fold (RFI = 3.99; RFN = 2.21; P = 0.001). The indoor density of parous Anopheles was reduced by 1.7-fold (RFI = 3.99; RFN = 2.21; P = 0.04) and that of infected Anopheles by 1.8-fold (RFI = 3.26; RFN = 1.78; P = 0.04). Indoor peak biting rates were observed between 02 a.m. to 04 a.m. in non-improved houses and from 02 a.m. to 06 a.m. in improved houses. CONCLUSION: Housing improvement contributed to reducing indoor residual anopheline density and malaria transmission. This highlights the need for policy specialists to further evaluate and promote aspects of house design as a complementary control tool that could reduce indoor human-vector contact and malaria transmission in similar epidemiological settings.

3.
Parasit Vectors ; 12(1): 501, 2019 Oct 26.
Artículo en Inglés | MEDLINE | ID: mdl-31655608

RESUMEN

Malaria still has a devastating impact on public health and welfare in Cameroon. Despite the increasing number of studies conducted on disease prevalence, transmission patterns or treatment, there are to date, not enough studies summarising findings from previous works in order to identify gaps in knowledge and areas of interest where further evidence is needed to drive malaria elimination efforts. The present study seeks to address these gaps by providing a review of studies conducted so far on malaria in Cameroon since the 1940s to date. Over 250 scientific publications were consulted for this purpose. Although there has been increased scale-up of vector control interventions which significantly reduced the morbidity and mortality to malaria across the country from a prevalence of 41% of the population reporting at least one malaria case episode in 2000 to a prevalence of 24% in 2017, the situation is not yet under control. There is a high variability in disease endemicity between epidemiological settings with prevalence of Plasmodium parasitaemia varying from 7 to 85% in children aged 6 months to 15 years after long-lasting insecticidal nets (LLINs) scale-up. Four species of Plasmodium have been recorded across the country: Plasmodium falciparum, P. malariae, P. ovale and P. vivax. Several primate-infecting Plasmodium spp. are also circulating in Cameroon. A decline of artemisinin-based combinations therapeutic efficacy from 97% in 2006 to 90% in 2016 have been reported. Several mutations in the P. falciparum chloroquine resistance (Pfcrt) and P. falciparum multidrug resistance 1 (Pfmdr1) genes conferring resistance to either 4-amino-quinoleine, mefloquine, halofanthrine and quinine have been documented. Mutations in the Pfdhfr and Pfdhps genes involved in sulfadoxine-pyrimethamine are also on the rise. No mutation associated with artemisinin resistance has been recorded. Sixteen anopheline species contribute to malaria parasite transmission with six recognized as major vectors: An. gambiae, An. coluzzii, An. arabiensis, An. funestus, An. nili and An. moucheti. Studies conducted so far, indicated rapid expansion of DDT, pyrethroid and carbamate resistance in An. gambiae, An. coluzzii, An. arabiensis and An. funestus threatening the performance of LLINs. This review highlights the complex situation of malaria in Cameroon and the need to urgently implement and reinforce integrated control strategies in different epidemiological settings, as part of the substantial efforts to consolidate gains and advance towards malaria elimination in the country.


Asunto(s)
Malaria/epidemiología , Malaria/prevención & control , Animales , Anopheles/clasificación , Anopheles/genética , Anopheles/parasitología , Camerún/epidemiología , Humanos , Resistencia a los Insecticidas , Malaria/terapia , Malaria/transmisión , Control de Mosquitos/tendencias , Mosquitos Vectores/clasificación , Mosquitos Vectores/genética , Mosquitos Vectores/parasitología , Plasmodium/clasificación , Plasmodium/patogenicidad , Prevalencia , Salud Pública
4.
Biomed Res Int ; 2019: 9709013, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31139663

RESUMEN

Malaria endemicity in Cameroon greatly varies according to ecological environment. In such conditions, parasitaemia, which is associated with fever, may not always suffice to define an episode of clinical malaria. The evaluation of malaria control intervention strategies mostly consists of identifying cases of clinical malaria and is crucial to promote better diagnosis for accurate measurement of the impact of the intervention. We sought out to define and quantify clinical malaria cases in children from three health districts in the Northern region of Cameroon. A cohort study of 6,195 children aged between 6 and 120 months was carried out during the raining season (July to October) between 2013 and 2014. Differential diagnosis of clinical malaria was performed using the parasite density and axillary temperature. At recruitment, patients with malaria-related symptoms (fever [axillary temperature ≥ 37.5°C], chills, severe malaise, headache, or vomiting) and a malaria positive blood smear were classified under clinical malaria group. The malaria attributable fraction was calculated using logistic regression models. Plasmodium falciparum was responsible for over 91% of infections. Children from Pitoa health district had the highest number of asymptomatic infections (45.60%) compared to those from Garoua and Mayo Oulo. The most suitable cut-off for the association between parasite densities and fever was found among children less than 24 months. Overall, parasite densities that ranged above 3,200 parasites per µl of blood could be used to define the malaria attributable fever cases. In groups of children aged between 24 and 59 months and 60 and 94 months, the optimum cut-off parasite density was 6,400 parasites per µl of blood, while children aged between 95 and 120 months had a cut-off of 800 parasites per µl of blood. In the same ecoepidemiological zone, clinical malaria case definitions are influenced by age and location (health district) and this could be considered when evaluating malaria intervention strategies in endemic areas.


Asunto(s)
Malaria/epidemiología , Animales , Camerún/epidemiología , Niño , Estudios de Cohortes , Geografía , Humanos , Malaria/parasitología , Parásitos/fisiología , Prevalencia , Sensibilidad y Especificidad
5.
PLoS One ; 14(5): e0215825, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31042729

RESUMEN

Although mother-to-child transmission of HIV has dramatically declined, the number of in utero HIV-exposed, uninfected infants is on the increase. HIV-exposed infants are at an increased risk of mortality, morbidity and slower early growth than their non-HIV exposed counterparts. Maternal HIV increases the risk of having preterm deliveries, intrauterine growth restriction and low birth weight babies. However, the mechanism underlying dysregulation of fetal growth in HIV-infected pregnant women is unknown. We sought to determine whether maternal HIV is associated with dysregulation of the insulin-like growth factor (IGF) axis, some angiogenic factors or other related biomarkers that regulate fetal growth. A total of 102 normotensive pregnant women were enrolled in a small cross-sectional study. Amongst these were thirty-one HIV-1 positive women receiving combination antiretroviral therapy (cART) (Mean age: 30.0 ± 5.1 years; % on ART: 83.9%; median plasma viral load: 683 copies/ml; median CD4 count: 350 cells/ul) and 71 HIV uninfected women (mean age: 27.3 ± 5.8) recruited at delivery. A panel of biomarkers including IGF1 and IGF binding proteins (IGFBP1, IGFBP3), angiopoietins (ANG) 1 and 2, matrix metalloproteinases (MMP) 2 and 9, and galectin 13, was measured in plasma collected from the placental intervillous space. The levels of IGF1, IGFBP1, ANG1, ANG2, MMP2, MMP9 and Gal-13 were not affected by maternal HIV, even when adjusted for maternal factors in linear regression models (all p>0.05). It was observed that HIV-infection in pregnancy did not significantly affect key markers of the IGF axis and angiogenic factors. If anything, it did not affect women. These findings highlight the importance of the use of ART during pregnancy, which maintains factors necessary for fetal development closer to those of healthy women. However, decrease in IGF1 levels might be exacerbated in women con-infected with HIV and malaria.


Asunto(s)
Angiopoyetinas/sangre , Antirretrovirales/uso terapéutico , Infecciones por VIH/tratamiento farmacológico , Factor I del Crecimiento Similar a la Insulina/metabolismo , Adulto , Biomarcadores/sangre , Camerún , Estudios Transversales , Femenino , Infecciones por VIH/complicaciones , Infecciones por VIH/metabolismo , Humanos , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/análisis , Proteína 1 de Unión a Factor de Crecimiento Similar a la Insulina/sangre , Factor I del Crecimiento Similar a la Insulina/análisis , Malaria/complicaciones , Malaria/diagnóstico , Metaloproteinasa 9 de la Matriz/sangre , Placenta/metabolismo , Placenta/patología , Embarazo , Adulto Joven
6.
PLoS One ; 14(2): e0212024, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-30779799

RESUMEN

The effectiveness of insecticide-based malaria vector control interventions in Africa is threatened by the spread and intensification of pyrethroid resistance in targeted mosquito populations. The present study aimed at investigating the temporal and spatial dynamics of deltamethrin resistance in An. gambiae s.l. populations from North Cameroon. Mosquito larvae were collected from 24 settings of the Garoua, Pitoa and Mayo Oulo Health Districts (HDs) from 2011 to 2015. Two to five days old female An. gambiae s.l. emerging from larval collections were tested for deltamethrin resistance using the World Health Organization's (WHO) standard protocol. Sub samples of test mosquitoes were identified to species using PCR-RFLP and genotyped for knockdown resistance alleles (Kdr 1014F and 1014S) using Hot Ligation Oligonucleotide Assay (HOLA). All the tested mosquitoes were identified as belonging to the An. gambiae complex, including 3 sibling species mostly represented by Anopheles arabiensis (67.6%), followed by Anopheles coluzzii (25.4%) and Anopheles gambiae (7%). Deltamethrin resistance frequencies increased significantly between 2011 and 2015, with mosquito mortality rates declining from 70-85% to 49-73% in the three HDs (Jonckheere-Terstra test statistic (JT) = 5638, P< 0.001), although a temporary increase of mortality rates (91-97%) was seen in the Pitoa and Mayo Oulo HDs in 2012. Overall, confirmed resistance emerged in 10 An. gambiae s.l. populations over the 24 field populations monitored during the study period, from 2011 to 2015. Phenotypic resistance was mostly found in urban settings compared with semi-urban and rural settings (JT = 5282, P< 0.0001), with a spatial autocorrelation between neighboring localities. The Kdr 1014F allelic frequencies in study HDs increased from 0-30% in 2011 to 18-61% in 2014-2015 (JT = 620, P <0.001), especially in An. coluzzii samples. The overall frequency of the Kdr 1014S allele was 0.1%. This study revealed a rapid increase and widespread deltamethrin resistance frequency as well as Kdr 1014F allelic frequencies in An. gambiae s.l. populations over time, emphasizing the urgent need for vector surveillance and insecticide resistance management strategies in Cameroon.


Asunto(s)
Anopheles/efectos de los fármacos , Proteínas de Insectos/genética , Resistencia a los Insecticidas , Nitrilos/farmacología , Piretrinas/farmacología , Animales , Anopheles/genética , Anopheles/crecimiento & desarrollo , Camerún , Femenino , Frecuencia de los Genes , Larva/efectos de los fármacos , Larva/genética , Larva/crecimiento & desarrollo , Malaria/prevención & control , Malaria/transmisión , Mosquitos Vectores/efectos de los fármacos , Mosquitos Vectores/genética , Mosquitos Vectores/crecimiento & desarrollo , Planificación Social , Análisis Espacio-Temporal , Remodelación Urbana
7.
Malar J ; 17(1): 450, 2018 Dec 04.
Artículo en Inglés | MEDLINE | ID: mdl-30514316

RESUMEN

BACKGROUND: Plasmodium falciparum infected erythrocytes sequestering in placental tissue release Plasmodium lactate dehydrogenase (pLDH) and histidine-rich protein-II (HRP-II). These proteins can be detected in peripheral blood using monoclonal antibody-based rapid diagnostic tests (RDTs). Nevertheless, studies to evaluate the reliability of RDTs in detecting placental malaria compared with microscopy of placental tissue impression smear (PTIS) as the gold standard are scarce. METHODS: Between August 2013 and January 2015, Giemsa-stained blood smears for peripheral blood smear (Pbs), placental intervillous space (IVS) blood smear and placental tissue impression smear (PTIS)] were prepared from HIV-negative women during delivery at the Marie Reine Medical Health Centre in Yaoundé, Cameroon. RDTs with monoclonal antibodies specific to HRP-II (P.f) or pLDH (Pan) antigens were used to screen maternal peripheral blood samples. RESULTS: The prevalence of malaria was 16%, 7.5%, 11.5%, 8% and 13% for One Step malaria HRP-II and pLDH RDTs, peripheral blood smear, IVS blood and placental tissue impression smears, respectively. The proportion of women positive by One Step malaria pLDH RDT and Pbs increased with parasite density in PTIS, while One Step malaria HRP-II RDT detected high proportion of infected women even with low parasite density. Although the prevalence of malaria infection by both microscopy and RDTs decreased significantly with mother age (0.0008 ≤ p ≤ 0.025), parity seemed to have very little influence. The sensitivity of One Step malaria HRP-II and pLDH RDTs were 96.15% and 61.53%, respectively, compared to 80.76% for Pbs (p = 0.014 and 0.0029, respectively). The specificity of these RDTs was 96.49% and 100%, respectively, compared to 100% for Pbs (p ≥ 0.12). In addition, the positive predictive values were 80.64% and 100% for HRP-II and pLDH-based RDTs, respectively, compared to 100% for Pbs (p < 0.0001 and 1, respectively), while the negative predictive values were 99.40% and 94.48%, respectively, compared to 97.16% for Pbs (p ≥ 0.49). The combination of One Step malaria HRP-II RDT and Pbs showed the similar performance as that observed with One Step malaria HRP-II RDT only. CONCLUSION: These results depict One Step malaria HRP-II RDT to be better in detecting placental P. falciparum infection in pregnant women compared to Giemsa-stained peripheral thick blood smear. This is important for better case management since microscopic examination of PTIS cannot be employed during pregnancy.


Asunto(s)
Malaria Falciparum/diagnóstico , Enfermedades Placentarias/diagnóstico , Plasmodium falciparum , Complicaciones Infecciosas del Embarazo/diagnóstico , Juego de Reactivos para Diagnóstico/parasitología , Adolescente , Adulto , Camerún , Estudios Transversales , Femenino , Humanos , Malaria Falciparum/sangre , Microscopía , Oportunidad Relativa , Placenta/parasitología , Embarazo , Reproducibilidad de los Resultados , Factores de Tiempo , Adulto Joven
8.
Lancet Infect Dis ; 18(6): 640-649, 2018 06.
Artículo en Inglés | MEDLINE | ID: mdl-29650424

RESUMEN

BACKGROUND: Scale-up of insecticide-based interventions has averted more than 500 million malaria cases since 2000. Increasing insecticide resistance could herald a rebound in disease and mortality. We aimed to investigate whether insecticide resistance was associated with loss of effectiveness of long-lasting insecticidal nets and increased malaria disease burden. METHODS: This WHO-coordinated, prospective, observational cohort study was done at 279 clusters (villages or groups of villages in which phenotypic resistance was measurable) in Benin, Cameroon, India, Kenya, and Sudan. Pyrethroid long-lasting insecticidal nets were the principal form of malaria vector control in all study areas; in Sudan this approach was supplemented by indoor residual spraying. Cohorts of children from randomly selected households in each cluster were recruited and followed up by community health workers to measure incidence of clinical malaria and prevalence of infection. Mosquitoes were assessed for susceptibility to pyrethroids using the standard WHO bioassay test. Country-specific results were combined using meta-analysis. FINDINGS: Between June 2, 2012, and Nov 4, 2016, 40 000 children were enrolled and assessed for clinical incidence during 1·4 million follow-up visits. 80 000 mosquitoes were assessed for insecticide resistance. Long-lasting insecticidal net users had lower infection prevalence (adjusted odds ratio [OR] 0·63, 95% CI 0·51-0·78) and disease incidence (adjusted rate ratio [RR] 0·62, 0·41-0·94) than did non-users across a range of resistance levels. We found no evidence of an association between insecticide resistance and infection prevalence (adjusted OR 0·86, 0·70-1·06) or incidence (adjusted RR 0·89, 0·72-1·10). Users of nets, although significantly better protected than non-users, were nevertheless subject to high malaria infection risk (ranging from an average incidence in net users of 0·023, [95% CI 0·016-0·033] per person-year in India, to 0·80 [0·65-0·97] per person year in Kenya; and an average infection prevalence in net users of 0·8% [0·5-1·3] in India to an average infection prevalence of 50·8% [43·4-58·2] in Benin). INTERPRETATION: Irrespective of resistance, populations in malaria endemic areas should continue to use long-lasting insecticidal nets to reduce their risk of infection. As nets provide only partial protection, the development of additional vector control tools should be prioritised to reduce the unacceptably high malaria burden. FUNDING: Bill & Melinda Gates Foundation, UK Medical Research Council, and UK Department for International Development.


Asunto(s)
Culicidae/efectos de los fármacos , Mosquiteros Tratados con Insecticida , Malaria/transmisión , Control de Mosquitos/métodos , Mosquitos Vectores/efectos de los fármacos , Piretrinas/farmacología , Adolescente , África del Sur del Sahara/epidemiología , Animales , Niño , Preescolar , Estudios de Cohortes , Humanos , India/epidemiología , Lactante , Resistencia a los Insecticidas , Internacionalidad , Malaria/epidemiología , Estudios Prospectivos , Organización Mundial de la Salud
9.
Parasit Vectors ; 10(1): 22, 2017 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-28077167

RESUMEN

BACKGROUND: As part of a study to determine the impact of insecticide resistance on the effectiveness of long-lasting insecticide treated nets (LLINs) in the north of Cameroon, the unexpectedly high density and anthropophilic behaviour of Anopheles rufipes lead us to investigate this species bionomics and role in human malaria parasite transmission. METHODS: For four consecutive years (2011-2014), annual cross-sectional sampling of adult mosquitoes was conducted during the peak malaria season (September-October) in three health districts in northern Cameroon. Mosquitoes sampled by human landing catch and pyrethrum spray catch methods were morphologically identified, their ovaries dissected for parity determination and Anopheles gambiae siblings were identified by molecular assay. Infection with P. falciparum and blood meal source in residual fauna of indoor resting anopheline mosquitoes were determined by enzyme-linked-immunosorbent assays. RESULTS: Anopheles gambiae (sensu lato) (s.l.) comprised 18.4% of mosquitoes collected with An. arabiensis representing 66.27% of the sibling species. The proportion of An. rufipes (2.7%) collected was high with a human-biting rate ranging between 0.441 and 11.083 bites/person/night (b/p/n) and an anthropophagic rate of 15.36%. Although overall the members of An. gambiae complex were responsible for most of the transmission with entomological inoculation rates (EIR) reaching 1.221 infective bites/person/night (ib/p/n), An. arabiensis and An. coluzzii were the most implicated. The roles of An. funestus, An. pharoensis and An. paludis were minor. Plasmodium falciparum circumsporozoite protein rate in Anopheles rufipes varied from 0.6 to 5.7% with EIR values between 0.010 and 0.481 ib/p/n. CONCLUSIONS: The study highlights the epidemiological role of An. rufipes alongside the members of the An. gambiae complex, and several other sympatric species in human malaria transmission during the wet season in northern Cameroon. For the first time in Cameroon, An. rufipes has been shown to be an important local malaria vector, emphasising the need to review the malaria entomological profile across the country as pre-requisite to effective vector management strategies.


Asunto(s)
Anopheles/parasitología , Insectos Vectores/parasitología , Malaria Falciparum/transmisión , Plasmodium falciparum/fisiología , Animales , Anopheles/clasificación , Anopheles/genética , Anopheles/fisiología , Camerún/epidemiología , Estudios Transversales , Femenino , Humanos , Mordeduras y Picaduras de Insectos/epidemiología , Mordeduras y Picaduras de Insectos/parasitología , Insectos Vectores/clasificación , Insectos Vectores/genética , Insectos Vectores/fisiología , Malaria Falciparum/epidemiología , Malaria Falciparum/parasitología , Control de Mosquitos , Estaciones del Año
10.
Malar J ; 15: 31, 2016 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-26791422

RESUMEN

BACKGROUND: All suspected cases of malaria should receive a diagnostic test prior to treatment with artemisinin-based combinations based on the new WHO malaria treatment guidelines. This study compared the accuracy and some operational characteristics of 22 different immunochromatographic antigen capture point-of- malaria tests (RDTs) in Cameroon to inform test procurement prior to deployment of artemisinin-based combinations for malaria treatment. METHODS: One hundred human blood samples (50 positive and 50 negative) collected from consenting febrile patients in two health centres at Yaoundé were used for evaluation of the 22 RDTs categorized as "Pf Only" (9) or "Pf + PAN" (13) based on parasite antigen captured [histidine rich protein II (HRP2) or lactate dehydrogenase (pLDH) or aldolase]. RDTs were coded to blind technicians performing the tests. The sensitivity, specificity, and predictive values of the positive and negative tests (PPV and NPV) as well as the likelihood ratios were assessed. The reliability and some operational characteristics were determined as the mean values from two assessors, and the Cohen's kappa statistic was then used to compare agreement. Light microscopy was the referent. RESULTS: Of all RDTs tested, 94.2 % (21/22) had sensitivity values greater than 90% among which 14 (63.6%) were 'Pf + PAN' RDTs. The specificity was generally lower than the sensitivity for all RDTs and poorer for "Pf Only" RDTs. The predictive values and likelihood ratios were better for non-HRP2 analytes for "Pf + PAN" RDTs. The Kappa value for most of the tests obtained was around 67% (95% CI 50-69%), corresponding to a moderate agreement. CONCLUSION: Overall, 94.2% (21/22) of RDTs tested had accuracy within the range recommended by the WHO, while one performed poorly, below acceptable levels. Seven "Pf + PAN" and 3 "Pf Only" RDTs were selected for further assessment based on performance characteristics. Harmonizing RDT test presentation and procedures would prevent mistakes of test performance and interpretation.


Asunto(s)
Antimaláricos/uso terapéutico , Artemisininas/uso terapéutico , Malaria/diagnóstico , Malaria/tratamiento farmacológico , Adolescente , Antígenos de Protozoos/análisis , Camerún , Niño , Preescolar , Pruebas Diagnósticas de Rutina/métodos , Femenino , Humanos , Lactante , Malaria/metabolismo , Masculino , Proteínas Protozoarias/análisis , Reproducibilidad de los Resultados
11.
Acta Trop ; 147: 23-30, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25861939

RESUMEN

Adverse pregnancy outcomes place the lives of mother and new born babies in jeopardy, especially in Sub Saharan Africa. Although a well-balanced network of the pregnancy-associated hormones and lipid fractions is necessary for healthy pregnancy, the profiles of some of these biomarkers alongside those of some cytokines in relation to placental malaria (PM) and poor pregnancy outcomes are unknown. Therefore between 2013 and 2014, paired peripheral and placental blood samples were collected from 135 Cameroonian women at delivery. Parasitaemia was determined microscopically and haemoglobin levels using Coulter counter. Plasma levels of cytokines (IFN-γ, IL-1ß and IL-7) and pregnancy-associated hormones (17ß oestradiol and progesterone) were measured by ELISA and the levels of lipid fractions: total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) determined by Colorimetric enzymatic methods. Parasitaemia was inversely related to parity, haemoglobin levels and birth weight (P≤0.019). While the levels of IFN-γ and cholesterol (total, HDL and LDL) were higher in peripheral plasma, those of IL-1ß, 17ß oestradiol, progesterone and triglyceride were higher in placental blood (P<0.001). Absence of PM was significantly associated with high plasma levels of IFN-γ, IL-7 and HDL-C and low plasma levels of 17ß oestradiol and TG. Moreover, IL-7 levels correlated positively and significantly with haemoglobin levels and with both peripheral and placental levels of progesterone. Baby birth weight increased with plasma levels of progesterone and HDL-C. Levels of IFN-γ correlated positively and significantly with HDL-C, but negatively with LDL-C; thus, might prevent pregnant women from atherogenic risk. Study of the inter-relationship between hormones, cytokines and lipids revealed that the association between IL-7 and progesterone and/or some lipid fractions followed inverse trends from that of IFN-γ. These results suggest that in PM, IFN-γ and IL-7 might protect against poor pregnancy outcomes, which decrease plasma levels of progesterone, maternal haemoglobin and HDL-C, leading to low birth weight. However, these cytokines may act differently with regards to progesterone and some lipid fractions. PM may also lower plasma levels of HDL-C and increase that of TG which is the most important risk factor for cardiovascular disorders and consequently poor pregnancy outcomes.


Asunto(s)
Citocinas/inmunología , Malaria/inmunología , Placenta/parasitología , Complicaciones Parasitarias del Embarazo/inmunología , Adolescente , Adulto , Camerún , HDL-Colesterol/metabolismo , LDL-Colesterol/metabolismo , Estradiol/metabolismo , Femenino , Hemoglobinas , Humanos , Hipertrigliceridemia/metabolismo , Recién Nacido de Bajo Peso , Recién Nacido , Interferón gamma/inmunología , Interleucina-1beta/inmunología , Interleucina-7/inmunología , Malaria/metabolismo , Parasitemia/inmunología , Parasitemia/metabolismo , Paridad , Placenta/inmunología , Placenta/metabolismo , Embarazo , Complicaciones Parasitarias del Embarazo/metabolismo , Resultado del Embarazo , Progesterona/metabolismo , Pronóstico , Adulto Joven
12.
Acta Trop ; 141(Pt A): 97-102, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25447267

RESUMEN

Despite intensive research on the immunpathology of placental malaria (PM), the role of some ß-chemokines known to attract inflammatory cells is less known. This study sought to determine the role of CXCL-10, IL-10, IL-19, IL-17A and IL-23 in placental malaria in women at delivery. Between 2010 and 2011, paired peripheral and placental blood specimens were collected from 139 Cameroonian women at delivery. Differential white blood cell counts and malaria parasitaemia were determined microscopically while the accumulation of parasites in the placenta was investigated through histological studies. Plasma levels of CXCL-10, IL-10, IL-17A, IL-19 and Il-23 were determined by ELISA. The cytokines IL-10, IL-17A and IL-23 were predominant in peripheral plasma from both infected and non-infected women. While IL-10 associated negatively with parity, IL-23 showed a positive correlation (p<0.05). The production of CXCL-10 was independent of parity and higher in placental plasma. There was an association between the plasma levels of IL-10 and CXCL-10 with malaria parasitaemia in the placenta impression smears, placental and peripheral blood and the presence of malaria pigments in the placenta tissue. Leukocyte accumulation into the intervillous space correlated positively with plasma levels of placental IL-17A (p<0.001). Parity also associated with peripheral IL-17A (p=0.016). The peripheral and placental plasma levels of CXCL-10 and IL-10 also correlated positively with monocyte counts (p=0.011-0.042) while a negative correlation was found with lymphocyte counts (p=0.017 to <0.001) of the impression smear. However, the levels of IL-10 in both peripheral and placental plasma and CXCL-10 in placental plasma only, were higher in low birth weight baby. With regards to IL-17A, its placental plasma level correlated positively with lymphocyte counts of placental blood (p=0.045). During PM, CXCL-10 might attract monocytes and lymphocytes into the placenta where they produce inflammatory cytokines such as IL-10 and IL-17A to modulate the disease, which affect baby weight.


Asunto(s)
Citocinas/sangre , Malaria Falciparum/sangre , Parasitemia/sangre , Placenta/parasitología , Complicaciones Parasitarias del Embarazo/sangre , Adolescente , Adulto , Biomarcadores/sangre , Camerún , Estudios de Casos y Controles , Quimiocina CXCL10/sangre , Quimiocina CXCL10/inmunología , Citocinas/inmunología , Femenino , Hemoproteínas/metabolismo , Humanos , Interleucina-10/sangre , Interleucina-10/inmunología , Interleucina-17/sangre , Interleucina-17/inmunología , Interleucina-23/sangre , Interleucina-23/inmunología , Interleucinas/sangre , Interleucinas/inmunología , Malaria Falciparum/inmunología , Monocitos , Parasitemia/inmunología , Paridad , Placenta/metabolismo , Embarazo , Complicaciones Parasitarias del Embarazo/inmunología , Adulto Joven
13.
Parasit Vectors ; 7: 262, 2014 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-24903710

RESUMEN

BACKGROUND: Malaria transmission in Cameroon is mediated by a plethora of vectors that are heterogeneously distributed across the country depending on the biotope. To effectively guide malaria control operations, regular update on the role of local Anopheles species is essential. Therefore, an entomological survey was conducted between August 2010 and May 2011 to evaluate the role of the local anopheline population in malaria transmission in three villages of the Ndop health district in the northwest region of Cameroon where malaria is holoendemic, as a means to acquiring evidence based data for improved vector intervention. METHODS: Mosquitoes were sampled both indoor and outdoor for four consecutive nights in each locality during each month of survey. Sampling was done by the human landing catch method on volunteers. Anopheles species were identified morphologically and their ovaries randomly dissected for parity determination. Infection with Plasmodium falciparum was detected by Circumsporozoite protein ELISA. Members of An. gambiae complex were further identified to molecular level by PCR and RFLP PCR. RESULTS: An. ziemanni was the main malaria vector and whether outdoor or indoor. The man biting rate for the vectors ranged from 6.75 to 8.29 bites per person per night (b/p/n). The entomological inoculation rate for this vector species was 0.0278 infectious bites per person per night (ib/p/n) in Mbapishi, 0.034 ib/p/n in Mbafuh, and 0.063 ib/p/n in Backyit. These were by far greater than that for An. gambiae. No difference was observed in the parity rate of these two vectors. PCR analysis revealed the presence of only An. colluzzi (M- form). CONCLUSIONS: An. ziemanni is an important local malaria vector in Ndop health district. The findings provide useful baseline information on the anopheles species composition, their distribution and role in malaria transmission that would guide the implementation of integrated vector management strategies in the locality.


Asunto(s)
Anopheles/clasificación , Anopheles/parasitología , Insectos Vectores/parasitología , Malaria/transmisión , Distribución Animal , Animales , Biodiversidad , Camerún/epidemiología , Conducta Alimentaria , Humanos , Mordeduras y Picaduras de Insectos , Insectos Vectores/fisiología , Malaria/epidemiología
14.
Acta Trop ; 124(3): 210-4, 2012 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-22935317

RESUMEN

Anti-vector intervention remains the most effective way of controlling malaria. Although in Cameroon and elsewhere focus is on the use of long-lasting insecticidal nets and indoor residual spraying, the efficacy of both methods greatly depends on the continuing susceptibility of the vectors to the insecticides used. The emergence and spread of insecticide resistance in the major malaria vectors constitute a huge challenge to control programmes. Consequently, routine monitoring and evaluation of vector resistance status to insecticides are mandatory for early detection of resistance should it arise, and effectively planning future anti-vector interventions especially in areas reputed for routine application in agriculture. The WHO bioassay kit was used to determine the susceptibility status of Anopheles gambiae s.l. populations to seven insecticides belonging to four classes (organochlorine, organophosphate, carbamate and pyrethroids) in Niete, an area of intense rubber cultivation in southern forested Cameroon. Species and molecular forms of An. gambiae s.l. as well as the presence of knock down resistance (kdr) mutations were determined using polymerase chain reaction (PCR) techniques. All Anopheles tested was identified as An. gambiae s.s. and of the M molecular form. Based on WHO classification, while the mosquitoes were fully (100%) susceptible to malathion and bendiocarb, resistance was confirmed to DDT and the pyrethroids, permethrin and lambda-cyhalothrin. The other pyrethroids (deltamethrin and cyfluthrin) showed signs of developing resistance. Resistance to DDT and pyrethroids is indicative of existing cross resistance mechanisms between these insecticides. The increase in knockdown times was greater than twofold that of the reference susceptible strain, suggesting the possible involvement of kdr mutations, also confirmed in this study. The findings highlight the need for constant evaluation, re-evaluation and monitoring of the insecticides for malaria vector control in Cameroon. However, bendiocarb and malathion can be used and may require alternation or combination with insecticides of other classes to better manage the occurrence and spread of resistance in Niete.


Asunto(s)
Anopheles/efectos de los fármacos , Resistencia a los Insecticidas , Insecticidas/farmacología , Piretrinas/farmacología , Agricultura , Animales , Anopheles/clasificación , Anopheles/genética , Camerún , Entomología/métodos , Femenino , Humanos , Reacción en Cadena de la Polimerasa/métodos , Goma
15.
Parasit Vectors ; 5: 197, 2012 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-22963986

RESUMEN

BACKGROUND: Development of large scale agro-industries are subject to serious environmental modifications. In malaria endemic areas this would greatly impact on the transmission paradigm. Two cross-sectional entomological surveys to characterize the Anopheles fauna and their entomological inoculation rates were conducted during May 2010 (peak rainy season) and December 2010 (peak dry season) in the intense rubber cultivated area of Niete in southern forested Cameroon. METHODS: Mosquitoes were sampled by night collections on human volunteers, identified morphologically and members of the Anopheles gambiae complex further identified to species and molecular form. Parity status was determined following the dissection of the ovaries. Plasmodium falciparum circumsporozoite antigen indices were estimated after the identification of CS antigen by ELISA and the average entomological inoculation rates determined. RESULTS: A total of 1187 Anopheles was collected, 419 (35.3%) in the rainy season and 768 (64.7%) in the dry season. Species found were the M molecular form of An. gambiae s.s (66.8%), An. ziemanni (28.3%), An. paludis (4.7%), An. smithii (0.2%). An. gambiae M-form was the principal species in the dry (56.2%) and wet (86.2%) seasons. Average overall entomological inoculation rate for the malaria vectors varied between the dry season (1.09 ib/p/n) and the rainy season (2.30 ib/p/n). CONCLUSIONS: Malaria transmission in Niete occurs both in the dry and rainy season with the intensities peaking in the dry season. This is unlike previous studies in other areas of southern forested Cameroon where transmission generally peaks in the rainy season. Environmental modifications due to agro-industrial activities might have influenced vector distribution and the dynamics of malaria transmission in this area. This necessitates the possible implementation of control strategies that are related to the eco-geography of the area.


Asunto(s)
Anopheles/crecimiento & desarrollo , Anopheles/parasitología , Plasmodium falciparum/aislamiento & purificación , Agricultura , Animales , Anopheles/clasificación , Camerún , Ecosistema , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Plasmodium falciparum/química , Dinámica Poblacional , Prevalencia , Proteínas Protozoarias/análisis , Goma , Estaciones del Año
16.
Am J Trop Med Hyg ; 84(2): 276-84, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21292899

RESUMEN

The malaria vaccine candidate antigens erythrocyte binding antigen 175 (EBA-175), merozoite surface protein 3 (MSP-3), and apical membrane antigen (AMA-1) from Plasmodium falciparum isolates from countries in central and west Africa were assessed for allelic diversity. Samples were collected on filter paper from 600 P. falciparum-infected symptomatic patients in Cameroon, Republic of Congo, Burkina Faso, Ghana, and Senegal and screened for class-specific amplification fragments. Genetic diversity, assessed by mean heterozygosity, was comparable among countries. We detected a clinical increase in eba 175 F-allele frequency from west to east across the study region. No statistical difference in msp-3 allele distribution between countries was observed. The ama-1 3D7 alleles were present at a lower frequency in central Africa than in West Africa. We also detected little to no genetic differentiation among sampling locations. This finding indicates that, at least at the level of resolution offered by restriction fragment length polymorphism analysis, these antigens showed remarkable genetic homogeneity throughout the region sampled, perhaps caused by balancing selection to maintain a diverse array of antigen haplotyes.


Asunto(s)
Antígenos de Protozoos/genética , Vacunas contra la Malaria/genética , Plasmodium falciparum/genética , Proteínas Protozoarias/genética , África Central , África Occidental , Alelos , Antígenos de Protozoos/inmunología , ADN Protozoario/genética , Variación Genética/genética , Heterocigoto , Humanos , Malaria Falciparum/genética , Malaria Falciparum/parasitología , Malaria Falciparum/prevención & control , Plasmodium falciparum/inmunología , Reacción en Cadena de la Polimerasa , Proteínas Protozoarias/inmunología
17.
Acta Trop ; 115(1-2): 131-6, 2010.
Artículo en Inglés | MEDLINE | ID: mdl-20206111

RESUMEN

Knowledge of baseline malaria transmission intensity in a given environment is important to guide malaria control interventions. In Cameroon, recent information on malaria transmission intensity is insufficient. Therefore, an entomological study was conducted in four ecologically different sites throughout the country to assess the seasonal patterns in malaria transmission intensity. Anopheles arabiensis was the main vector in six of the nine study sites, while An. gambiae sensu stricto was the most important vector in the other three sites. Clear differences in entomological inoculation rates (EIR) were observed between the study sites, ranging from 0.1 infective bites per person per night in the sahelian zone of the country to 5.5 infective bites per person per night in the forest zone. Based on the observed behaviour of the vectors, insecticide-treated bed nets will be highly effective in controlling malaria. However, in the high transmission areas, additional measures will be needed to reduce the malaria burden to acceptable levels.


Asunto(s)
Anopheles/clasificación , Anopheles/crecimiento & desarrollo , Insectos Vectores , Malaria/epidemiología , Malaria/transmisión , Animales , Camerún/epidemiología , Femenino , Humanos , Mosquiteros Tratados con Insecticida , Malaria/prevención & control , Control de Mosquitos/métodos
18.
J Ethnopharmacol ; 112(2): 271-7, 2007 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-17428630

RESUMEN

The methanolic extract (DAT), fractions (FRS) and four flavonoids, namely Gancaonin Q (1), Stipulin (2), Angusticornin B (3) and Bartericin A (4), isolated from the twigs of Dorstenia angusticornis (Moraceae), were tested for their in vitro antimicrobial activity. A total of 22 microbial cultures belonging to three Candida species, 6 Gram-positive and 13 Gram-negative bacterial species were used in this study. The inhibition zones (IZ) of the test samples against the pathogens were determined by the Agar Hole Diffusion test while the Liquid dilution method was used to determine their minimal inhibition concentrations (MIC) and their minimal microbicidal concentrations (MMC). Results indicate that DAT, compounds 3 and 4 inhibited the growth of all test pathogens. DAT, FRS 3-6, compounds 3 and 4 were both antibacterial and anticandidal. A single-dose oral toxicity performed in accordance with the OPPTS 870.1100 and OECD 401guideline showed that DAT was not toxic. Our findings provide a possible basis for the potential use of twigs from Dorstenia angusticornis in the treatment of infectious diseases.


Asunto(s)
Antiinfecciosos/farmacología , Flavonoides/farmacología , Moraceae/química , Animales , Antiinfecciosos/química , Antiinfecciosos/toxicidad , Bacterias/efectos de los fármacos , Chalconas/química , Chalconas/farmacología , Difusión , Flavonoides/toxicidad , Hongos/efectos de los fármacos , Metanol , Pruebas de Sensibilidad Microbiana , Tamaño de los Órganos/efectos de los fármacos , Extractos Vegetales/química , Extractos Vegetales/farmacología , Extractos Vegetales/toxicidad , Tallos de la Planta/química , Ratas , Ratas Wistar , Solventes , Aumento de Peso/efectos de los fármacos
19.
Malar J ; 6: 5, 2007 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-17233883

RESUMEN

BACKGROUND: Malaria is a major public health problem in Cameroon. Unlike in the southern forested areas where the epidemiology of malaria has been better studied prior to the implementation of control activities, little is known about the distribution and role of anophelines in malaria transmission in the coastal areas. METHODS: A 12-month longitudinal entomological survey was conducted in Tiko, Limbe and Idenau from August 2001 to July 2002. Mosquitoes captured indoors on human volunteers were identified morphologically. Species of the Anopheles gambiae complex were identified using the polymerase chain reaction (PCR). Mosquito infectivity was detected by the enzyme-linked immunosorbent assay and PCR. Malariometric indices (plasmodic index, gametocytic index, parasite species prevalence) were determined in three age groups (<5 yrs, 5-15 yrs, >15 yrs) and followed-up once every three months. RESULTS: In all, 2,773 malaria vectors comprising Anopheles gambiae (78.2%), Anopheles funestus (17.4%) and Anopheles nili (7.4%) were captured. Anopheles melas was not anthropophagic. Anopheles gambiae had the highest infection rates. There were 287, 160 and 149 infective bites/person/year in Tiko, Limbe and Idenau, respectively. Anopheles gambiae accounted for 72.7%, An. funestus for 23% and An. nili for 4.3% of the transmission. The prevalence of malaria parasitaemia was 41.5% in children <5 years of age, 31.5% in those 5-15 years and 10.5% in those >15 years, and Plasmodium falciparum was the predominant parasite species. CONCLUSION: Malaria transmission is perennial, rainfall dependent and An. melas does not contribute to transmission. These findings are important in the planning and implementation of malaria control activities in coastal Cameroon and West Africa.


Asunto(s)
Anopheles , Mordeduras y Picaduras de Insectos , Insectos Vectores , Malaria/transmisión , Parasitemia/transmisión , Adolescente , Animales , Anopheles/clasificación , Anopheles/genética , Anopheles/crecimiento & desarrollo , Anopheles/parasitología , Camerún/epidemiología , Niño , Preescolar , Humanos , Insectos Vectores/clasificación , Insectos Vectores/crecimiento & desarrollo , Insectos Vectores/parasitología , Malaria/epidemiología , Malaria/parasitología , Parasitemia/epidemiología , Parasitemia/parasitología , Reacción en Cadena de la Polimerasa , Prevalencia , Lluvia , Estaciones del Año
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