RESUMEN
BACKGROUND: Methylene blue (MB) was the first synthetic antimalarial to be discovered and was used during the late 19th and early 20th centuries against all types of malaria. MB has been shown to be effective in inhibiting Plasmodium falciparum in culture, in the mouse model and in rhesus monkeys. MB was also shown to have a potent ex vivo activity against drug-resistant isolates of P. falciparum and P. vivax. In preclinical studies, MB acted synergistically with artemisinin derivates and demonstrated a strong effect on gametocyte reduction in P. falciparum. MB has, thus, been considered a potentially useful partner drug for artemisinin-based combination therapy (ACT), particularly when elimination is the final goal. The aim of this study was to review the scientific literature published until early 2017 to summarise existing knowledge on the efficacy and safety of MB in the treatment of malaria. METHODS: This systematic review followed PRISMA guidelines. Studies reporting on the efficacy and safety of MB were systematically searched for in relevant electronic databases according to a pre-designed search strategy. The search (without language restrictions) was limited to studies of humans published until February 2017. RESULTS: Out of 474 studies retrieved, a total of 22 articles reporting on 21 studies were eligible for analysis. The 21 included studies that reported data on 1504 malaria patients (2/3 were children). Older studies were case series and reports on MB monotherapy while recent studies were mainly controlled trials of combination regimens. MB was consistently shown to be highly effective in all endemic areas and demonstrated a strong effect on P. falciparum gametocyte reduction and synergy with ACT. MB treatment was associated with mild urogenital and gastrointestinal symptoms as well as blue coloration of urine. In G6PD-deficient African individuals, MB caused a slight but clinically non-significant haemoglobin reduction. CONCLUSIONS: More studies are needed to define the effects of MB in P. falciparum malaria in areas outside Africa and against P. vivax malaria. Adding MB to ACT could be a valuable approach for the prevention of resistance development and for transmission reduction in control and elimination programs. SYSTEMATIC REVIEW REGISTRATION: This study is registered at PROSPERO (registration number CRD42017062349 ).
Asunto(s)
Inhibidores Enzimáticos/uso terapéutico , Malaria Falciparum/tratamiento farmacológico , Azul de Metileno/uso terapéutico , Inhibidores Enzimáticos/farmacología , Femenino , Humanos , Masculino , Azul de Metileno/farmacologíaRESUMEN
Several life-threatening infections, a major risk to adult solid organ transplant (SOT) recipients on immunosuppressive therapy, can be prevented by immunization. We analyzed sociodemographic parameters and the immunization status of adult liver transplant recipients (LTX-R, n=267) and renal transplant recipients (RTX-R, n=197) SOT recipients at the Transplantation Center, Berlin, Germany. Date, number, and provider of recommended vaccines were recorded and seroprotection rates determined. The social status in both groups was similar. Most patients (89%) were not adequately informed about immunizations; and if informed, main sources were physicians (47%) and the media (40%). Vaccinations were predominantly provided by family doctors (LTX-R, 66%; RTX-R, 31%) or hemodialysis centers (RTX-R, 37%). Before transplantation, RTX-R had significantly more often received booster vaccinations against tetanus and diphtheria (P<0.005), and a primary hepatitis B immunization (55%); whereas in LTX-R, post-transplant vaccinations against hepatitis A (16%) and pneumococcal disease (13%) were more frequent. Seroprotection rates against tetanus were fairly high in LTX-R (85.3%) and RTX-R (86.8%), and considerably lower for diphtheria, hepatitis A, and influenza. Immunization rates are too low in SOT recipients. Improvement will depend on a more active role of health care providers.
Asunto(s)
Encuestas Epidemiológicas , Trasplante de Riñón , Trasplante de Hígado , Vacunación , Adolescente , Adulto , Anciano , Anticuerpos Antibacterianos/sangre , Anticuerpos Antivirales/sangre , Vacunas Bacterianas/administración & dosificación , Vacunas Bacterianas/inmunología , Femenino , Alemania , Humanos , Inmunización/estadística & datos numéricos , Trasplante de Riñón/inmunología , Trasplante de Hígado/inmunología , Masculino , Persona de Mediana Edad , Inmunología del Trasplante , Vacunación/normas , Vacunación/estadística & datos numéricos , Vacunas Virales/administración & dosificación , Vacunas Virales/inmunología , Adulto JovenRESUMEN
Genetic host factors play a substantial role in susceptibility to and severity of malaria, which continues to cause at least one million deaths per year. Recently, members of the toll-like receptor (TLR) family have been shown to be involved in recognition of the etiologic organism Plasmodium falciparum: The glycosylphosphatidylinisitol anchor induces signaling in host cells via TLR-2 and -4, while hemozoin-induced immune activation involves TLR-9. Binding of microbial ligands to the respective TLRs triggers the release of pro-inflammatory cytokines via the TLR/IL-1 receptor (TIR) domain and may contribute to the host response, including pro-inflammatory cytokine induction and malarial fever. In a case-control study among 870 Ghanaian children, we examined the influence of TLR-2, -4, and -9 polymorphisms in susceptibility to severe malaria. TLR-2 variants common in Caucasians and Asians were completely absent. However, we found a new, rare mutation (Leu658Pro), which impairs signaling via TLR-2. We failed to detect any polymorphisms within the TLR-9/interleukin-1 receptor domain. Two frequent TLR-9 promoter polymorphisms did not show a clear association with malaria severity. In contrast, the TLR-4-Asp299Gly variant occurred at a high rate of 17.6% in healthy controls, and was even more frequent in severe malaria patients (24.1%, p<0.05). Likewise, TLR-4-Thr399Ile was seen in 2.4% of healthy children and in 6.2% of patients (p=0.02). TLR-4-Asp299Gly and TLR-4-Thr399Ile conferred an 1.5- and 2.6-fold increased risk of severe malaria, respectively. These findings suggest TLR4-mediated responses to malaria in vivo and TLR-4 polymorphisms to be associated with disease manifestation. However some gray areas also suggest the scope for further improvements.
Asunto(s)
Inmunidad Innata/genética , Malaria Falciparum/inmunología , Polimorfismo de Nucleótido Simple/inmunología , Receptor Toll-Like 4/genética , Niño , Preescolar , Femenino , Predisposición Genética a la Enfermedad , Ghana , Humanos , Lactante , Malaria Falciparum/genética , Masculino , Receptor Toll-Like 2/genética , Receptor Toll-Like 2/inmunología , Receptor Toll-Like 4/inmunología , Receptor Toll-Like 9/genética , Receptor Toll-Like 9/inmunologíaRESUMEN
Staphylococcus aureus is emerging globally. Treatment of infections is complicated by increasing antibiotic resistance. We collected clinical data and swabs of returnees with skin and soft tissue infections (SSTI) at 13 travel-clinics in Europe (www.staphtrav.eu). Sixty-two percent (196/318) SSTI patients had S. aureus-positive lesions, of which almost two-thirds (122/196) were Panton-Valentine leukocidin (PVL) positive. PVL was associated with disease severity, including hospitalization for SSTI (OR 5.2, 95% CI 1.5-18.2). In returnees with SSTI, longer travel and more intense population contact were risk factors for nasal colonization with PVL-positive S. aureus. Imported S. aureus frequently proved resistant to trimethoprim-sulfamethoxazole (21%), erythromycin (21%), tetracycline (20%), ciprofloxacin (13%), methicillin (12%) and clindamycin (8%). Place of exposure was significantly (p < 0.05) associated with predominant resistance phenotypes and spa genotypes: Latin America (methicillin; t008/CC24/304), Africa (tetracycline, trimethoprim-sulfamethoxazole; t084/CC84, t314/singleton, t355/CC355), South Asia (trimethoprim-sulfamethoxazole, ciprofloxacin; t021/CC21/318), South-East Asia (clindamycin; t159/CC272). USA300-like isolates accounted for 30% of all methicillin-resistant S. aureus imported to Europe and were predominantly (71%) acquired in Latin America. Multi-resistance to non-ß-lactams were present in 24% of imports and associated with travel to South Asia (ORcrude 5.3, 95% CI 2.4-11.8), even after adjusting for confounding by genotype (ORadjusted 3.8, 95% 1.5-9.5). Choosing randomly from compounds recommended for the empiric treatment of severe S. aureus SSTI, 15% of cases would have received ineffective antimicrobial therapy. These findings call for the development of regionally stratified guidance on the antibiotic management of severe imported S. aureus disease and put the infected and colonized traveller at the centre of interventions against the global spread of multi-resistant S. aureus.
Asunto(s)
Farmacorresistencia Bacteriana Múltiple , Infecciones de los Tejidos Blandos/epidemiología , Infecciones de los Tejidos Blandos/microbiología , Infecciones Cutáneas Estafilocócicas/epidemiología , Infecciones Cutáneas Estafilocócicas/microbiología , Staphylococcus aureus/efectos de los fármacos , Viaje , Adulto , África , Antibacterianos/farmacología , Asia Sudoriental , Toxinas Bacterianas/genética , Portador Sano/epidemiología , Portador Sano/microbiología , Europa (Continente)/epidemiología , Exotoxinas/genética , Femenino , Genotipo , Humanos , América Latina , Leucocidinas/genética , Masculino , Persona de Mediana Edad , Tipificación Molecular , Mucosa Nasal/microbiología , Estudios Prospectivos , Infecciones de los Tejidos Blandos/patología , Proteína Estafilocócica A , Infecciones Cutáneas Estafilocócicas/patología , Staphylococcus aureus/genética , Staphylococcus aureus/aislamiento & purificación , Factores de Virulencia/genética , Adulto JovenRESUMEN
To investigate the global occurrence of trimethoprim-sulfamethoxazole resistance and the genetic mechanisms of trimethoprim resistance, we analysed Staphylococcus aureus from travel-associated skin and soft-tissue infections treated at 13 travel clinics in Europe. Thirty-eight per cent (75/196) were trimethoprim-resistant and 21% (41/196) were resistant to trimethoprim-sulfamethoxazole. Among methicillin-resistant S. aureus, these proportions were 30% (7/23) and 17% (4/23), respectively. DfrG explained 92% (69/75) of all trimethoprim resistance in S. aureus. Travel to South Asia was associated with the highest risk of acquiring trimethoprim-sulfamethoxazole-resistant S. aureus. We conclude that globally dfrG is the predominant determinant of trimethoprim resistance in human S. aureus infection.
Asunto(s)
Staphylococcus aureus/genética , Tetrahidrofolato Deshidrogenasa/genética , Resistencia al Trimetoprim , Proteínas Bacterianas/genética , Europa (Continente) , Humanos , Infecciones de los Tejidos Blandos/microbiología , Infecciones Estafilocócicas/microbiología , Infecciones Cutáneas Estafilocócicas/microbiología , Staphylococcus aureus/clasificación , Staphylococcus aureus/aislamiento & purificación , ViajeRESUMEN
Drug resistance in Plasmodium falciparum affects prevention of malaria in pregnancy. In a cross-sectional study of 530 pregnant Ghanaian women, P. falciparum dihydrofolate reductase (DHFR) gene mutations linked with pyrimethamine resistance were assessed and associations with pyrimethamine intake were analyzed. P. falciparum infected 69% of women without pyrimethamine use, 59% of those who had a history of pyrimethamine consumption but a negative urine test, and 53% of individuals with a positive urine test. Eighty-one percent, 43%, and 74% of the isolates contained the mutations Asn-108, Ile-51, and Arg-59, respectively. Thr-108 occurred in 8%. Pyrimethamine use was associated with increased frequencies of Asn-108 and Arg-59 but not of Ile-51 or Thr-108. In women with prophylaxis, wild-type parasites were absent and anemia tended to be more common with an increasing number of DHFR gene mutations. Pyrimethamine appears to be not adequately effective in this part of Ghana, most likely due to the predominance of resistant parasites. Selection for resistance following insufficient prophylaxis could possibly affect the efficacy of future intermittent sulfadoxine-pyrimethamine treatment.
Asunto(s)
Alelos , Antimaláricos/uso terapéutico , Malaria Falciparum/prevención & control , Plasmodium falciparum/enzimología , Complicaciones Parasitarias del Embarazo/prevención & control , Pirimetamina/uso terapéutico , Tetrahidrofolato Deshidrogenasa/genética , Animales , ADN Protozoario/química , ADN Protozoario/genética , ADN Protozoario/aislamiento & purificación , Resistencia a Medicamentos/genética , Femenino , Ghana , Humanos , Malaria Falciparum/parasitología , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/genética , Mutación Puntual , Reacción en Cadena de la Polimerasa , Embarazo , Complicaciones Parasitarias del Embarazo/parasitologíaRESUMEN
Little is known about the distribution and disease association of multiple Plasmodium falciparum infections in pregnant women. Genotyping of the merozoite surface protein-1 region was performed in 332 P. falciparum infected pregnant women in Ghana, and clinical and epidemiologic data were obtained. Overall, 68% of the women were infected with more than one strain (mean number of strains per carrier = 2.9). The multiplicity of infection decreased significantly with an increasing number of pregnancies, and infection with multiple P. falciparum strains was significantly associated with anemia. In logistic regression, women infected with four or more strains were 2.3 times more likely to be anemic than women harboring fewer strains. This association, however, was only observed in women with up to three pregnancies. The results suggest that with increasing gravidity and subsequent infections with multiple strains effective immune mechanisms against more and more strains develop. In pregnant women, the multiplicity of infection may be an important factor for the acquisition and maintenance of immunity against malaria.
Asunto(s)
Malaria Falciparum/parasitología , Complicaciones Parasitarias del Embarazo/parasitología , Anemia/etiología , Femenino , Número de Embarazos , Humanos , Modelos Logísticos , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/inmunología , Embarazo , Complicaciones Parasitarias del Embarazo/tratamiento farmacológico , Complicaciones Parasitarias del Embarazo/inmunologíaRESUMEN
The influence of alpha(+)-thalassemia on malaria in pregnancy was assessed in a cross-sectional study of 530 women in Ghana. Plasmodial infections, alpha(+)-thalassemia, serum levels of C-reactive protein, and antimalarial drugs in urine were determined. The alpha-globin genotypes did not correlate with the prevalence of Plasmodium falciparum-infection and parasite densities. However, Plasmodium malariae tended to be more frequent in alpha(+)-thalassemic women (P = 0.05). Excluding women with residual antimalarials, a significant excess of P. malariae was observed in alpha(+)-thalassemic individuals. Febrile responses (P = 0.05) and inflammation (CRP > 0.6 mg/dl, P = 0.06) appeared to be less common in infected alpha(+)-thalassemic women and were also comparatively rare in parasitemic individuals who harbored double species infections with P. falciparum and P. malariae. Plasmodium malariae may influence the pathogenesis of falciparum malaria leading to a low prevalence of inflammation and febrile responses in alpha(+)-thalassemic women.
Asunto(s)
Malaria/epidemiología , Malaria/genética , Plasmodium/aislamiento & purificación , Complicaciones Hematológicas del Embarazo/epidemiología , Complicaciones Parasitarias del Embarazo/epidemiología , Talasemia alfa/genética , Adulto , Animales , Estudios Transversales , Ensayo de Inmunoadsorción Enzimática , Femenino , Predisposición Genética a la Enfermedad , Ghana/epidemiología , Humanos , Malaria/patología , Plasmodium/clasificación , Plasmodium malariae/aislamiento & purificación , Reacción en Cadena de la Polimerasa , Embarazo , Índice de Severidad de la Enfermedad , Talasemia alfa/sangreRESUMEN
Resistance of Plasmodium falciparum to pyrimethamine is associated with a non-silent point mutation of the parasite dihydrofolate reductase (DHFR) gene (Ser108 --> Asn108). Wide-scale use of antimalarials is thought to contribute to the emergence of drug resistance. In 131 P. falciparum-infected children in rural Nigeria, the frequency of the resistant Asn108 genotype was assessed by enzymatic restriction digestion of polymerase chain reaction-amplified DHFR sequences and compared with residual pyrimethamine blood levels. The prevalence of the Asn108 variant was 41.2%. In 18.3% of the isolates, both the Asn108 and the wild-type alleles were present. In contrast to the high prevalence of resistant genotypes, residual pyrimethamine blood levels were detected in only 4%. Furthermore, age was found to be a determinant of the parasite genotype since the proportion of Asn108 variants decreased with age (P < 0.05). These findings indicate that additional, unidentified factors, rather than selection by residual drug levels alone, might be responsible for the emergence of pyrimethamine-resistant parasite genotypes.
Asunto(s)
Antimaláricos/uso terapéutico , Malaria Falciparum/parasitología , Plasmodium falciparum/genética , Mutación Puntual , Pirimetamina/uso terapéutico , Tetrahidrofolato Deshidrogenasa/genética , Distribución por Edad , Animales , Antimaláricos/sangre , Antimaláricos/farmacología , Niño , Preescolar , Estudios Transversales , ADN Protozoario/análisis , Resistencia a Medicamentos/genética , Genes Protozoarios , Genotipo , Humanos , Lactante , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/epidemiología , Nigeria/epidemiología , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/enzimología , Reacción en Cadena de la Polimerasa/métodos , Prevalencia , Pirimetamina/sangre , Pirimetamina/farmacologíaRESUMEN
The rate of malarial parasitemia in children and adults was assessed by microscopy and the polymerase chain reaction in a holoendemic area in Nigeria. A high rate of subpatent Plasmodium falciparum parasitemia (19.6%) was found. Plasmodium malariae and P. ovale infections were common in a rural area (26.1% and 14.8%) but were observed sporadically in individuals from an urban area. Simultaneous infections with P. falciparum, P. malariae, and P. ovale were frequent in the rural area (11.7% triple infections). The rate of triple infections was higher than expected from the prevalences of each species (P < 0.00001). Spleen enlargement was associated with mixed infections of P. falciparum and P. malariae (odds ratio [OR] = 5.9, 95% confidence interval [CI] 3.0-11.7) and less frequently observed in individuals without detectable parasitemia (OR = 0.06, 95% CI = 0.01-0.3). Spleen enlargement and titers of antibodies to schizonts were positively correlated with parasite densities. The results also suggest that in some individuals a long-lasting subpatent parasitemia might occur.
Asunto(s)
Malaria Falciparum/epidemiología , Malaria/epidemiología , Adolescente , Adulto , Animales , Anticuerpos Antiprotozoarios/aislamiento & purificación , Antígenos de Protozoos/aislamiento & purificación , Niño , Preescolar , Estudios Transversales , Femenino , Humanos , Lactante , Malaria/parasitología , Masculino , Persona de Mediana Edad , Nigeria/epidemiología , Plasmodium/inmunología , Plasmodium/aislamiento & purificación , Plasmodium falciparum/inmunología , Plasmodium falciparum/aislamiento & purificación , Plasmodium malariae/inmunología , Plasmodium malariae/aislamiento & purificación , Prevalencia , Salud Rural , Bazo/parasitología , Salud UrbanaRESUMEN
In sub-Saharan Africa, anaemia in pregnancy results from multiple causes including malaria, iron deficiency and haemoglobinopathies. In a cross-sectional study among 530 pregnant women in Ghana in November-December 1998, red blood cell indices were analysed with respect to malaria, serum concentrations of ferritin and C-reactive protein (CRP), and the haemoglobin and alpha-globin genotypes. Anaemia (haemoglobin [Hb] < 11 g/dL) was found in 54% of the women; 63% harboured malaria parasites at predominantly low numbers. Ferritin levels were considerably influenced by malaria and inflammatory processes (CRP > 0.6 mg/dL). Depending on the definition applied, the prevalence of iron deficiency ranged between 5% and 46%. The HbAS trait was observed in 14%, HbAC and elevated HbF in 7% each, and sickle cell disease in 1%. Heterozygous beta-thalassaemia was present in 1% of the women and alpha(+)-thalassaemia in 33% (29% heterozygous, 4% homozygous). Women with HbAS had higher malaria parasite densities than those with HbAA. In individuals with highly elevated HbF (> 10%), parasitaemia occurred in 27% only. Low gravidity, second trimester of pregnancy, malaria, raised CRP levels, and homozygous alpha(+)-thalassaemia were independent risk factors for anaemia in multivariate analysis. alpha(+)-Thalassaemia, however, was associated with a lesser degree of malarial anaemia when compared to non-thalassaemic women. Iron deficiency appears not to be a major health problem in this population. Haemoglobinopathies are common but, except for homozygous alpha(+)-thalassaemia, do not substantially contribute to anaemia in pregnancy. alpha(+)-Thalassaemia ameliorates malarial anaemia in pregnant women.
Asunto(s)
Hemoglobinopatías/epidemiología , Malaria/epidemiología , Complicaciones Hematológicas del Embarazo/epidemiología , Complicaciones Parasitarias del Embarazo/epidemiología , Anemia Ferropénica/sangre , Anemia Ferropénica/epidemiología , Proteína C-Reactiva/análisis , Estudios Transversales , Femenino , Ferritinas/sangre , Ghana/epidemiología , Número de Embarazos , Hemoglobinopatías/sangre , Hemoglobinas/análisis , Humanos , Malaria/sangre , Embarazo , Complicaciones Hematológicas del Embarazo/sangre , Complicaciones Parasitarias del Embarazo/sangre , Análisis de Regresión , Factores de RiesgoRESUMEN
Childhood anaemia in sub-Saharan Africa is often caused by Plasmodium falciparum malaria. The influence of subpatent, multi-species and polyclonal infections with malaria parasites on haematological parameters was assessed in 1996/97 in clinically healthy children in Nigeria. Of the 228 children studied, 64% were anaemic by the WHO age-dependent criteria. A univariate analysis of risk factors indicated that the prevalence of anaemia was dependent on the number of Plasmodium species detected by species-specific PCR (P < 0.0001). Furthermore, the prevalence of anaemia increased gradually with the complexity (P < 0.003) as well as with the extent of P. falciparum parasitaemia (P < 0.0001). A logistic regression analysis revealed that individuals with an enlarged spleen tended to be anaemic. The number of Plasmodium species by which an individual was infected was independently associated with anaemia (P < 0.03). ANOVA revealed that the age-corrected values for haemoglobin (Hb) and red blood cells (RBCs) were mainly influenced by the occurrence of mixed infections. Haematological parameters were also influenced by the number of different P. falciparum clones by which an individual was infected. Hb levels and RBC counts were further diminished by additional infections with P. malariae and/or P. ovale. However, the effect of multi-species infections on haematological parameters exceeded that of multi-clonal infections.
Asunto(s)
Anemia/parasitología , Malaria/parasitología , Distribución por Edad , Análisis de Varianza , Anemia/epidemiología , Animales , Niño , Preescolar , Estudios Transversales , Humanos , Lactante , Modelos Logísticos , Malaria/epidemiología , Nigeria/epidemiología , Parasitemia/epidemiología , Parasitemia/parasitología , Plasmodium/clasificación , Factores de RiesgoRESUMEN
We evaluated the performance of an immunochromatographic assay (ICA) in comparison with light microscopy and PCR for the detection of Giardia duodenalis in stool samples from 558 Rwandan children. The association of infection with clinical symptoms was similar for the three diagnostic tools. The ICA equally detected parasites of assemblages A and B and was more sensitive than light microscopy (50.4 versus 29.5% of PCR-positive samples considered true positive; p <0.0001). Hence, the ICA shows superior sensitivity compared with microscopy but still misses half of the G. duodenalis infections detected by PCR in this hyperendemic area.
Asunto(s)
Cromatografía de Afinidad/métodos , Giardia lamblia/clasificación , Giardia lamblia/aislamiento & purificación , Giardiasis/diagnóstico , Heces/parasitología , Giardiasis/epidemiología , Humanos , Microscopía , Reacción en Cadena de la Polimerasa , Rwanda/epidemiología , Sensibilidad y EspecificidadRESUMEN
Although chloroquine (CQ) monotherapy is now generally inadequate for the treatment of Plasmodium falciparum malaria in northern Ghana--recently, 58% of 225 children failed treatment by day 14--use of the drug continues because of its low cost and wide availability. The risk factors associated with CQ-treatment failure in this region of Africa, including the T76 mutation in the chloroquine resistance transporter (pfcrt) gene and the Y86 mutation in the multidrug resistance (pfmdr1) gene of P. falciparum, have now been investigated, and genotype-failure indices (GFI) have been calculated. Treatment failure was found to be associated with young age, poor nutritional status, pfcrt T76 and pfmdr1 Y86, and early treatment failure (ETF) was also associated with high parasitaemia. The presence and concentration of 'residual' CQ in the blood of patients immediately before they were treated with CQ for the present study appeared to have no effect on outcome. Presence at recruitment of pfcrt T76 or pfmdr1 Y86 or both mutations increased the risk of treatment failure by 3.2-, 2.4- and 4.5-fold, and the risk of ETF by 9.8-, 2.7- and 10.2-fold, respectively. The pfcrt T76 GFI for clinical and all treatment failures were 2.8 and 1.4, respectively. These indices were relatively low in the younger children, those with malnutrition, and those with high parasitaemias when treated. Residual CQ did not affect the GFI substantially. Both pfcrt T76 and, to a lesser extent, pfmdr1 Y86 would be useful tools for the surveillance of CQ resistance in northern Ghana. In the current transition phase to alternative first-line treatment for P. falciparum malaria, it should be possible to provide estimates of the level of CQ resistance by monitoring the prevalences of these mutations.
Asunto(s)
Transportadoras de Casetes de Unión a ATP/genética , Antimaláricos/uso terapéutico , Cloroquina/uso terapéutico , Malaria Falciparum/tratamiento farmacológico , Proteínas de la Membrana/genética , Proteínas Protozoarias/genética , Animales , Niño , Preescolar , Farmacorresistencia Microbiana , Femenino , Humanos , Lactante , Recién Nacido , Malaria Falciparum/complicaciones , Malaria Falciparum/parasitología , Masculino , Desnutrición/complicaciones , Proteínas de Transporte de Membrana , Mutación , Parasitemia/tratamiento farmacológico , Plasmodium falciparum/genética , Insuficiencia del TratamientoRESUMEN
Mefloquine resistance in Plasmodium falciparum, the most dangerous of the four pathogenic malaria parasites of humans, is established in several endemic regions of the world. After a promising start, resistance has developed to disturbing extents in some areas, whereas in many regions it remains an effective drug. In this article, Frank Mockenhaupt reviews the factors that are likely to influence the development of mefloquine resistance, its possible mechanism and its geographical spread.
RESUMEN
The Plasmodium falciparum chloroquine resistance transporter gene (pfcrt) T76 and multidrug resistance gene analogue (pfmdr1) Y86 mutations are associated with chloroquine(CQ)-resistance. In isolates from 172 pregnant women living in the area of Agogo, Ghana, pfcrt T76 was detected in 69% and pfmdr1 Y86 in 66%. Pfcrt T76 but not pfmdr1 Y86 was more prevalent in samples from women with residual CQ in urine or serum. Parasite densities and multiplicity of infection of pfmdr wild type but not of resistant isolates were reduced by CQ. Adjusted for CQ and pyrimethamine (PYR) in urine, the P. falciparum dihydrofolate reductase (pfdhfr) N108 mutation which confers PYR-resistance was 3.1 and 3 times, respectively, more likely to be detected in isolates containing pfcrt and pfmdr1 mutations than in those comprising wild type alleles. Pfcrt, pfmdr, and pfdhfr mutations are frequent in P. falciparum from this part of Ghana which may limit the choice of drugs for the prevention of malaria in pregnancy. The association of CQ- and PYR-resistance mutations independent of recent drug use could indicate accelerated development of resistance to structurally unrelated drugs. Alternatively, it may reflect selection of resistance in persisting infections due to no longer detectable drug pressure.
Asunto(s)
Transportadoras de Casetes de Unión a ATP , Malaria Falciparum/epidemiología , Proteínas de la Membrana/genética , Plasmodium falciparum/genética , Complicaciones Parasitarias del Embarazo/epidemiología , Proteínas Protozoarias/genética , Tetrahidrofolato Deshidrogenasa/genética , Adolescente , Adulto , Animales , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Antimaláricos/orina , Cloroquina/farmacología , Cloroquina/uso terapéutico , Cloroquina/orina , ADN Protozoario/sangre , ADN Protozoario/genética , Resistencia a Medicamentos , Femenino , Ghana/epidemiología , Humanos , Transmisión Vertical de Enfermedad Infecciosa/prevención & control , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/transmisión , Proteínas de Transporte de Membrana , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/enzimología , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Embarazo , Complicaciones Parasitarias del Embarazo/tratamiento farmacológico , Prevalencia , Pirimetamina/farmacología , Pirimetamina/uso terapéutico , Pirimetamina/orinaRESUMEN
The in vitro antiplasmodial activities of 14 plant species traditionally used in Central America for the treatment of malaria or fever were evaluated. Lipophilic extracts of Piper hispidum, Siparuna andina, S. pauciflora, S. tonduziana, and Xylopia cf. frutescens, proved to be active against both a chloroquine-sensitive and a resistant strain of Plasmodium falciparum. IC50 values ranged between 3.0 microg/ml and 21.9 microg/ml; however, moderate cytotoxicity of active extracts was observed. Bioactivity-guided fractionation of Piper hispidum yielded 2',4, 6'-trihydroxy-4'-methoxydihydrochalcone (asebogenin) as an active compound.
Asunto(s)
Antimaláricos/farmacología , Fitoterapia , Plantas Medicinales/uso terapéutico , Plasmodium falciparum/efectos de los fármacos , Animales , Antimaláricos/química , América Central , Técnicas In Vitro , Plantas Medicinales/químicaRESUMEN
Alpha-thalassaemia is common in malaria-endemic regions and is considered to confer protection from clinical disease due to infection with Plasmodium falciparum. In vitro, sensitivity to chloroquine (CQ) of P. falciparum infecting alpha-thalassaemic erythrocytes is reduced. We examined, in a cross-sectional study of 405 Nigerian children, associations between alpha-globin genotypes, blood concentrations of CQ, and P. falciparum parasitaemia. Of the children, 44% were alpha+-thalassaemic (36.8% heterozygous, 7.6% homozygous). CQ in blood and P. falciparum-infection were observed in 52 and 80%, respectively. CQ was more frequently found in homozygous alpha+-thalassaemic (71%) than in non-thalassaemic children (50%; odds ratio, 2.42; 95% confidence interval, 1.01-5.8). Among children with CQ in blood and despite similar drug concentrations, alpha+-thalassaemic individuals had fewer infections below the threshold of microscopy which were detectable by PCR only, and they had a higher prevalence of elevated parasitaemia than non-thalassaemic children. No such differences were discernible among drug-free children. CQ displays a lowered efficacy in the suppression of P. falciparum parasitaemia in alpha+-thalassaemic children; hence protection against malaria due to alpha+-thalassaemia may be obscured in areas of intense CQ usage. Moreover, alpha+-thalassaemia may contribute to the expansion of CQ resistance.
Asunto(s)
Antimaláricos/uso terapéutico , Cloroquina/uso terapéutico , Malaria Falciparum/tratamiento farmacológico , Parasitemia/tratamiento farmacológico , Talasemia alfa/complicaciones , Animales , Antimaláricos/sangre , Antimaláricos/farmacología , Niño , Preescolar , Cloroquina/sangre , Cloroquina/farmacología , Estudios Transversales , Resistencia a Medicamentos , Femenino , Genotipo , Humanos , Lactante , Malaria Falciparum/sangre , Malaria Falciparum/complicaciones , Masculino , Nigeria/epidemiología , Oportunidad Relativa , Parasitemia/sangre , Parasitemia/complicaciones , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/aislamiento & purificación , Reacción en Cadena de la Polimerasa , Prevalencia , Estudios Retrospectivos , Sensibilidad y Especificidad , Resultado del Tratamiento , Talasemia alfa/sangre , Talasemia alfa/genéticaRESUMEN
BACKGROUND AND OBJECTIVE: The serum transferrin receptor (sTfR) concentration in an individual reflects the extent of erythropoietic activity and is considered a useful marker of iron deficiency independent of concurrent inflammation or infection. However, data on the impact of malaria on this parameter are ambiguous. We have examined potential associations of asymptomatic and mild Plasmodium falciparum-infections and of several erythrocyte variants with sTfR values in South West Nigeria. DESIGN AND METHODS: In a cross-sectional study among 161 non-hospitalized children, sTfR concentrations and P. falciparum parasitemia were assessed. In addition, hemoglobin (Hb) and serum ferritin values, Hb-types, glucose-6-phosphate dehydrogenase (G6PD)deficiency and a-globin genotypes were determined and the effects of these factors on sTfR levels were analyzed by univariate and multivariate statistical methods. RESULTS: P. falciparum-infection was present in 77% of the children. Mean sTfR levels were higher in infected than in non-infected children (geometric mean, 3.68, 95% confidence interval [3.5-3.9] vs. 2.99 [2.7-3.3] mg/L; p = 0.0009). There was a significant trend for higher sTfR values with increasing parasite density. sTfR values decreased continuously with age. Hb-types, G6PD-, and a-globin genotypes did not correlate with sTfR levels. In the multivariate analysis, age, Hb and log ferritin values, and parasite density of P. falciparum were independently associated with log sTfR values. INTERPRETATION AND CONCLUSIONS: sTfR concentrations are increased in asymptomatic and mild P. falciparum-infections suggesting adequate bone marrow response in this condition. The diagnostic value of sTfR levels for iron deficiency may be impaired in areas where stable malaria occurs.
Asunto(s)
Malaria Falciparum/sangre , Receptores de Transferrina/sangre , Factores de Edad , Animales , Niño , Preescolar , Femenino , Ferritinas/sangre , Deficiencia de Glucosafosfato Deshidrogenasa/parasitología , Hemoglobina C , Hemoglobina Falciforme , Humanos , Lactante , Recién Nacido , Malaria Falciparum/epidemiología , Malaria Falciparum/patología , Masculino , Análisis Multivariante , Nigeria/epidemiología , Talasemia alfa/parasitologíaRESUMEN
In a study performed in Tamale, in the Northern region of Ghana, cystatin C, a new and sensitive indicator of the glomerular filtration rate (GFR), was used to estimate the frequency of renal dysfunction in 78 children with uncomplicated, Plasmodium falciparum malaria. The excretion in urine of albumin, immunoglobulin G and alpha1-microglobulin was also investigated. Plasma concentrations of cystatin C were found to be elevated in 17% of the children, indicating subclinical impairment of renal function. As most (85%) of the children had glomerular as well as tubular patterns of proteinuria, it appears that both glomerulonephritis and damage to tubular cells often occur in P. falciparum malaria.