Acute human leptospirosis in a Caribbean region of Colombia: From classic to emerging risk factors.

BACKGROUND: Leptospirosis is a zoonosis of worldwide incidence, with a broad spectrum of health risk factors. AIM: The objective was to determine risk factors associated with acute human leptospirosis and to explore predictive variables of risk to human leptospirosis. METHODS: The study was carried out in the Department of Córdoba, in the north of Colombia. We conducted a longitudinal prospective descriptive study with non-probabilistic sampling, which included 339 patients suspected of leptospirosis. Positive cases were confirmed by MAT and PCR. The determination of social and environmental risk factors was done with a survey on epidemiological and environmental variables to establish an association between cases of leptospirosis and risk factors as well as predictive variables. RESULTS: We found 19.8% (67/339) cases of acute leptospirosis, and the seroprevalence was 27.1% (92/339). The most frequent serogroups were Sejroe, Australis, Pomona, Batavie, Pyrogenes and Grippotyphosa. We identified the following risk factors: age between 10 and 19 years (OR = 2.571; 95% CI); pig ownership (OR = 2.019; 95% CI); bathing or recreational activities in lake/lagoon (OR = 3.85; 95% CI) and in dams (OR = 3.0; 95% CI); floodings 30 days before the onset of symptoms (OR = 2.019; 95% CI), and a mean temperature of 28°C (p 0.044; 95%CI). As significant predictor variables, we identified age (10-19 years), bathing or recreational activities in the lake/lagoon, and flooding 30 days before symptoms were again evidenced. This region presents classic risk factors (pig ownership) and emerging environmental risk factors (recreational practice or bathing in a lake/lagoon and flooding 30 days before the onset of symptoms), and demographic factors such as young age (10-19 years). CONCLUSIONS: These factors are also predictors of human cases of acute leptospirosis and provide contextual information on environmental and public health that should be considered for epidemiological surveillance in this endemic area.

Transcriptional Reprogramming of Candida tropicalis in Response to Isoespintanol Treatment.

Candida tropicalis, an opportunistic pathogen, ranks among the primary culprits of invasive candidiasis, a condition notorious for its resistance to conventional antifungal drugs. The urgency to combat these drug-resistant infections has spurred the quest for novel therapeutic compounds, with a particular focus on those of natural origin. In this study, we set out to evaluate the impact of isoespintanol (ISO), a monoterpene derived from Oxandra xylopioides, on the transcriptome of C. tropicalis. Leveraging transcriptomics, our research aimed to unravel the intricate transcriptional changes induced by ISO within this pathogen. Our differential gene expression analysis unveiled 186 differentially expressed genes (DEGs) in response to ISO, with a striking 85% of these genes experiencing upregulation. These findings shed light on the multifaceted nature of ISO's influence on C. tropicalis, spanning a spectrum of physiological, structural, and metabolic adaptations. The upregulated DEGs predominantly pertained to crucial processes, including ergosterol biosynthesis, protein folding, response to DNA damage, cell wall integrity, mitochondrial activity modulation, and cellular responses to organic compounds. Simultaneously, 27 genes were observed to be repressed, affecting functions such as cytoplasmic translation, DNA damage checkpoints, membrane proteins, and metabolic pathways like trans-methylation, trans-sulfuration, and trans-propylamine. These results underscore the complexity of ISO's antifungal mechanism, suggesting that it targets multiple vital pathways within C. tropicalis. Such complexity potentially reduces the likelihood of the pathogen developing rapid resistance to ISO, making it an attractive candidate for further exploration as a therapeutic agent. In conclusion, our study provides a comprehensive overview of the transcriptional responses of C. tropicalis to ISO exposure. The identified molecular targets and pathways offer promising avenues for future research and the development of innovative antifungal therapies to combat infections caused by this pathogenic yeast.

Antigen Discovery in Circulating Extracellular Vesicles From Plasmodium vivax Patients.

Plasmodium vivax is the most widely distributed human malaria parasite with 7 million annual clinical cases and 2.5 billion people living under risk of infection. There is an urgent need to discover new antigens for vaccination as only two vaccine candidates are currently in clinical trials. Extracellular vesicles (EVs) are small membrane-bound vesicles involved in intercellular communication and initially described in reticulocytes, the host cell of P. vivax, as a selective disposal mechanism of the transferrin receptor (CD71) in the maturation of reticulocytes to erythrocytes. We have recently reported the proteomics identification of P. vivax proteins associated to circulating EVs in P. vivax patients using size exclusion chromatography followed by mass spectrometry (MS). Parasite proteins were detected in only two out of ten patients. To increase the MS signal, we have implemented the direct immuno-affinity capture (DIC) technique to enrich in EVs derived from CD71-expressing cells. Remarkably, we identified parasite proteins in all patients totaling 48 proteins and including several previously identified P. vivax vaccine candidate antigens (MSP1, MSP3, MSP7, MSP9, Serine-repeat antigen 1, and HSP70) as well as membrane, cytosolic and exported proteins. Notably, a member of the Plasmodium helical interspersed sub-telomeric (PHIST-c) family and a member of the Plasmodium exported proteins, were detected in five out of six analyzed patients. Humoral immune response analysis using sera from vivax patients confirmed the antigenicity of the PHIST-c protein. Collectively, we showed that enrichment of EVs by CD71-DIC from plasma of patients, allows a robust identification of P. vivax immunogenic proteins. This study represents a significant advance in identifying new antigens for vaccination against this human malaria parasite.

Immune Response and Microbiota Profiles during Coinfection with Plasmodium vivax and Soil-Transmitted Helminths.

The role of the gut microbiota during coinfection with soil-transmitted helminths (STH) and Plasmodium spp. is poorly understood. We examined peripheral blood and fecal samples from 130 individuals who were either infected with Plasmodium vivax only, coinfected with P. vivax and STH, infected with STH alone, or not infected with either P. vivax or STH. In addition to a complete blood count (CBC) with differential, transcriptional profiling of peripheral blood samples was performed by transcriptome sequencing (RNA-Seq), fecal microbial communities were determined by 16S rRNA gene sequencing, and circulating cytokine levels were measured by bead-based immunoassays. Differences in blood cell counts, including an increased percentage of neutrophils, associated with a transcriptional signature of neutrophil activation, were driven primarily by P. vivax infection. P. vivax infection was also associated with increased levels of interleukin 6 (IL-6), IL-8, and IL-10; these cytokine levels were not affected by STH coinfection. Surprisingly, P. vivax infection was more strongly associated with differences in the microbiota than STH infection. Children infected with only P. vivax exhibited elevated Bacteroides and reduced Prevotella and Clostridiaceae levels, but these differences were not observed in individuals coinfected with STH. We also observed that P. vivax parasitemia was higher in the STH-infected population. When we used machine learning to identify the most important predictors of the P. vivax parasite burden (among P. vivax-infected individuals), bacterial taxa were the strongest predictors of parasitemia. In contrast, circulating transforming growth factor ß (TGF-ß) was the strongest predictor of the Trichuris trichiura egg burden. This study provides unexpected evidence that the gut microbiota may have a stronger link with P. vivax than with STH infection.IMPORTANCEPlasmodium (malaria) and helminth parasite coinfections are frequent, and both infections can be affected by the host gut microbiota. However, the relationship between coinfection and the gut microbiota is unclear. By performing comprehensive analyses on blood/stool samples from 130 individuals in Colombia, we found that the gut microbiota may have a stronger relationship with the number of P. vivax (malaria) parasites than with the number of helminth parasites infecting a host. Microbiota analysis identified more predictors of the P. vivax parasite burden, whereas analysis of blood samples identified predictors of the helminth parasite burden. These results were unexpected, because we expected each parasite to be associated with greater differences in its biological niche (blood for P. vivax and the intestine for helminths). Instead, we find that bacterial taxa were the strongest predictors of P. vivax parasitemia levels, while circulating TGF-ß levels were the strongest predictor of helminth parasite burdens.

Plasma-derived extracellular vesicles from Plasmodium vivax patients signal spleen fibroblasts via NF-kB facilitating parasite cytoadherence.

Plasmodium vivax is the most widely distributed human malaria parasite. Previous studies have shown that circulating microparticles during P. vivax acute attacks are indirectly associated with severity. Extracellular vesicles (EVs) are therefore major components of circulating plasma holding insights into pathological processes. Here, we demonstrate that plasma-derived EVs from Plasmodium vivax patients (PvEVs) are preferentially uptaken by human spleen fibroblasts (hSFs) as compared to the uptake of EVs from healthy individuals. Moreover, this uptake induces specific upregulation of ICAM-1 associated with the translocation of NF-kB to the nucleus. After this uptake, P. vivax-infected reticulocytes obtained from patients show specific adhesion properties to hSFs, reversed by inhibiting NF-kB translocation to the nucleus. Together, these data provide physiological EV-based insights into the mechanisms of human malaria pathology and support the existence of P. vivax-adherent parasite subpopulations in the microvasculature of the human spleen.

Absence of knockdown mutations in pyrethroid and DDT resistant populations of the main malaria vectors in Colombia.

BACKGROUND: Knockdown resistance (kdr) is a well-characterized target-site insecticide resistance mechanism that is associated with DDT and pyrethroid resistance. Even though insecticide resistance to pyrethroids and DDT have been reported in Anopheles albimanus, Anopheles benarrochi sensu lato (s.l.), Anopheles darlingi, Anopheles nuneztovari s.l., and Anopheles pseudopunctipennis s.l. malaria vectors in Latin America, there is a knowledge gap on the role that kdr resistance mechanisms play in this resistance. The aim of this study was to establish the role that kdr mechanisms play in pyrethroid and DDT resistance in the main malaria vectors in Colombia, in addition to previously reported metabolic resistance mechanisms, such as mixed function oxidases (MFO) and nonspecific esterases (NSE) enzyme families. METHODS: Surviving (n = 62) and dead (n = 67) An. nuneztovari s.l., An. darlingi and An. albimanus mosquitoes exposed to diagnostic concentrations of DDT and pyrethroid insecticides were used to amplify and sequence a ~ 225 bp fragment of the voltage-gated sodium channels (VGSC) gene. This fragment spanning codons 1010, 1013 and 1014 at the S6 segment of domain II to identify point mutations, which have been associated with insecticide resistance in different species of Anopheles malaria vectors. RESULTS: No kdr mutations were detected in the coding sequence of this fragment in 129 samples, 62 surviving mosquitoes and 67 dead mosquitoes, of An. darlingi, An. nuneztovari s.l. and An. albimanus. CONCLUSION: Mutations in the VGSC gene, most frequently reported in other species of the genus Anopheles resistant to pyrethroid and DDT, are not associated with the low-intensity resistance detected to these insecticides in some populations of the main malaria vectors in Colombia. These results suggest that metabolic resistance mechanisms previously reported in these populations might be responsible for the resistance observed.

Insecticide Resistance and Its Intensity in Populations of Malaria Vectors in Colombia.

Insecticide resistance in malaria vectors threatens malaria prevention and control efforts. In Colombia the three primary vectors, Anopheles darlingi, An. nuneztovari s.l., and An. albimanus, have reported insecticide resistance to pyrethroids, organophosphates, carbamates, and DDT; however, the insecticide resistance monitoring is not continuous, and the data on the prevalence of resistance is scarce and geographically limited. We describe the resistance levels and intensity of previously detected resistant populations among primary malaria vectors from the most endemic malaria areas in Colombia. The study was carried out in 10 localities of five states in Colombia. Bioassays were carried out following the methodology of CDC Bottle Bioassay using the discriminating concentration and in order to quantify the intensity the specimens were exposed to 2, 5, and 10X discriminating concentrations. Five insecticides were tested: deltamethrin, lambda-cyhalothrin, alpha-cypermethrin, permethrin, and DDT. The results provide evidence of low resistance intensity and resistance highly localized to pyrethroids and DDT in key malaria vectors in Colombia. This may not pose a threat to malaria control yet but frequent monitoring is needed to follow the evolution of insecticide resistance.

Baseline in vivo, ex vivo and molecular responses of Plasmodium falciparum to artemether and lumefantrine in three endemic zones for malaria in Colombia.

Background: Colombia began using artemisinin-based combination therapies for the treatment of uncomplicated Plasmodium falciparum malaria in 2006. It is necessary to implement resistance surveillance to antimalarial drugs in order to promptly detect changes in parasite susceptibility. The aim of this study was to establish a susceptibility baseline of P. falciparum to artemether-lumefantrine using three monitoring tools. Methods: Patients with uncomplicated malaria treated with artemether-lumefantrine underwent clinical and parasitological follow-up over 28 days. Ex vivo test was performed using the microtest technique for chloroquine, arthemeter, dihydroartemisinin and lumefantrine. Pfmdr1 copy number and polymorphisms in Pfk13, Pfatp6, Pfcrt and Pfmdr1 genes were analyzed. Results: From a total of 150 screened patients, 49 completed follow-up for 28 days. All treated patients had adequate clinical and parasitological responses. Parasitic clearance showed a drastic reduction of parasite biomass at 24 hours and complete elimination at 48 hours. One hundred eleven isolates were processed, all exhibited high susceptibility to artemisinins and a slight decrease in susceptibility to lumefantrine. No genetic polymorphisms associated with resistance to artemisinin were found. Conclusion: This study generated a susceptibility baseline in response to therapy with Coartem (artemether-lumefantrine) with numerical reference values, which will allow data comparison with future studies to systematically monitor changes in the parasite and to provide an early alert to the health authorities.

Malaria por Plasmodium vivax o P. falciparum en hospital de tercer nivel en la región más endémica de Colombia / Malaria due to Plasmodium vivax or P. falciparum in a tertiary hospital in the most endemic region of Colombia

Problema: En Colombia hay pocos informes sobre paludismo grave, en especial producidos bajo protocolos bien sustentados. Objetivo: Describir las características clínicas de pacientes del Hospital San Jerónimo (HSJ), de Montería, en 2009-2010, e identificar y cuantificar los síndromes clínicos graves. Metodología: Estudio descriptivo, retrospectivo, transversal, de todos los pacientes hospitalizadoscon diagnóstico de paludismo. Resultados: Hubo 126 pacientes con paludismo en el HSJ; 74% fueron remitidos de municipios circunvecinos; Plasmodium vivax causó 60% de los casos; 54% fueron mujeres (29 de 68 embarazadas, es decir, con malaria gestacional); fueron pacientes jóvenes (23.3 ± 19.3 años); el promedio de evolución de su paludismo actual fue cuatro a cinco días; la parasitemia promedio al ingresar al HSJ fue 13 628 ± 26 790 parásitos/microlitro. La triada clásica de fiebre, escalofrío y cefalea se encuentra en al menos dos de cada tres pacientes al ingresar. El promedio de la hemoglobina indica anemia moderada. Los 126 pacientes aportaron 194 eventos de complicaciones. Las complicacionesmás frecuentes fueron (porcentaje sobre 126 enfermos): trombocitopenia 76%; anemia (< 7 g/dL de hemoglobina) 17%; falla renal 10%; falla hepática 10%; complicación cerebral (fiebre + convulsiones, sin coma: siete casos; fiebre + convulsiones + coma: un caso) 6%; cinco casos fueron por P. vivax, dos por P. falciparum y uno por ambas especies (mixta); falla de dos a tres sistemas 11%. Conclusiones: Se requiere adelantar estudios en Colombia sobre malaria grave que evalúen de manera integral los pacientes, con protocolos bien definidos, y que comparen criterios diagnósticos de gravedad y pautas de tratamiento para poder elaborar una norma autóctona sobre la materia. (Acta Med Colomb 2015; 40-294-304).

Problem: In Colombia there are few reports on severe malaria, especially produced under well supported protocols. Objective: To describe the clinical characteristics of patients at the Hospital San Jeronimo (HSJ) of Montería, 2009-2010, and identify and quantify the severe clinical syndromes. Methodology: A descriptive, retrospective, cross-sectional study of all patients hospitalized with a diagnosis of malaria. Results: There were 126 patients with malaria in the HSJ; 74% were referred from surrounding y municipalities; Plasmodium vivax caused 60% of cases; 54% were women (29 of 68 were pregnant women, namely with gestational malaria); patients were young (23.3 ± 19.3 years); the average evolution of its current malaria was 4-5 days; the average parasitemia when entering the HSJ was 13 628 ± 26 790 parasites / microliter. The classic triad of fever, chills and headache were found in at least two out of three patients on admission. The average hemoglobin indicates moderate anemia. The 126 patients provided 194 adverse events and complications. The most frequent complications were (percentage of 126 patients): thrombocytopenia 76%; anemia (<7 g/dL hemoglobin) 17%; renal failure 10%; liver failure 10%; cerebral complication (fever + seizures without coma: 7 cases, fever + convulsions + coma: 1 case) 6%; five cases were due to P. vivax, 2 to P. falciparum and 1 to both species (mixed); failure of 2-3 systems 11%. Conclusions: The development of studies on severe malaria is required in Colombia to comprehensively assess patients with well-defined protocols and diagnostic criteria which compare diagnostic criteria of severity and treatment guidelines to develop an indigenous rule on the matter. (Acta Med Colomb 2015; 40-294-304).

The effects of Plasmodium vivax gestational malaria on the clinical and immune status of pregnant women in Northwestern Colombia / Efectos de la malaria gestacional por Plasmodium vivax sobre el estado clínico e inmune en gestantes del Noroccidente de Colombia

Abstract Objetive: The study explored the effects of Plasmodium vivax infection on the balance of pro- versus anti- inflammatory cytokines and chemokines and their relationship with some clinical and epidemiology outcomes. Methods: Thirty-five pregnant women were recruited. Of these, 15 subjects had malaria at delivery (GM+), and 20 had no exposition to infection throughout the pregnancy (GM-) and at delivery. Epidemiological and clinical data were recorded after reviewing the clinical records. At delivery, whole blood from the mother as well as placental tissue was collected. Diagnosis of infection was performed by thick smear and a polymerase chain reaction (PCR). Expression of pro-inflammatory and anti-inflammatory cytokines and chemokines was measured by a real time PCR. Results: The clinical and epidemiological variables explored were similar in both groups, with the exception of gestational age. When comparing the GM+ group with the GM- group, it is clear that although the differences generally are not significant, pro- inflammatory cytokines are elevated in both maternal blood and placental; anti-inflammatory ones are elevated in the mother and reduced in the placenta, and the chemokines are reduced in both compartments, except for MCP-1 which is elevated in all. Conclusion: The results appear to be strongly affected by the small number of women with GM by P. vivax at childbirth. Additional studies are needed with larger groups in this and other regions of the country.

Resumen Objetivo: En este estudio se determinó el efecto de la infección por Plasmodium vivax en el balance de citoquinas pro-inflamatorias/anti-inflamatorias y quemoquinas y su relación con algunas variables epidemiológicas y clínicas. Métodos: Se reclutaron 35 gestantes, 15 con malaria en el momento del parto (GM+) y 20 sin malaria en ningún momento de la gestación (GM-) Los datos epidemiológicos y clínicos fueron colectados a partir de la historia clínica. En el momento del parto fueron tomadas muestras de sangre periférica materna y tejido placentario. El diagnóstico fue realizado mediante gota gruesa y reaccion en cadena de la polimerasa (PCR). La expresión de citoquinas pro-inflamatorias/anti-inflamatorias y quimioquinas, fueron medidas por PCR en tiempo real. La expresión de citoquinas pro-inflamatorias/anti-inflamatorias y quemoquinas, fueron medidas por PCR en tiempo real. Resultados: En las variables epidemiológicas y clínicas, los datos fueron similares en ambos grupos. Al comparar el grupo GM+ con el grupo GM-, resulta claro que, aunque las diferencias, en general, no son significativas, las citoquinas proinflamatorias están elevadas tanto en sangre materna como placentaria, las antiinflamatorias están elevadas en la madre y reducidas en la placenta, y las quimioquinas están reducidas en ambos compartimentos, excepto la MCP-1 que está elevada en ambos. Conclusión. Los resultados parecen estar fuertemente afectados por la cantidad pequeña de mujeres con MG por P. vivax en el parto. Es necesario adelantar estudios adicionales con más mujeres tanto en esta región como en otros lugares.

The Effects of Plasmodium vivax Gestational Malaria on the Clinical and Immune Status of Pregnant Women in Northwestern Colombia.

OBJECTIVE: The study explored the effects of Plasmodium vivax infection on the balance of pro- versus anti- inflammatory cytokines and chemokines and their relationship with some clinical and epidemiology outcomes. METHODS: Thirty-five pregnant women were recruited. Of these, 15 subjects had malaria at delivery (GM+), and 20 had no exposition to infection throughout the pregnancy (GM-) and at delivery. Epidemiological and clinical data were recorded after reviewing the clinical records. At delivery, whole blood from the mother as well as placental tissue was collected. Diagnosis of infection was performed by thick smear and a polymerase chain reaction (PCR). Expression of pro-inflammatory and anti-inflammatory cytokines and chemokines was measured by a real time PCR. RESULTS: The clinical and epidemiological variables explored were similar in both groups, with the exception of gestational age. When comparing the GM+ group with the GM- group, it is clear that although the differences generally are not significant, pro- inflammatory cytokines are elevated in both maternal blood and placental; anti-inflammatory ones are elevated in the mother and reduced in the placenta, and the chemokines are reduced in both compartments, except for MCP-1 which is elevated in all. CONCLUSION: The results appear to be strongly affected by the small number of women with GM by P. vivax at childbirth. Additional studies are needed with larger groups in this and other regions of the country.

OBJETIVO: En este estudio se determinó el efecto de la infección por Plasmodium vivax en el balance de citoquinas pro-inflamatorias/anti-inflamatorias y quemoquinas y su relación con algunas variables epidemiológicas y clínicas. MÉTODOS: Se reclutaron 35 gestantes, 15 con malaria en el momento del parto (GM+) y 20 sin malaria en ningún momento de la gestación (GM-) Los datos epidemiológicos y clínicos fueron colectados a partir de la historia clínica. En el momento del parto fueron tomadas muestras de sangre periférica materna y tejido placentario. El diagnóstico fue realizado mediante gota gruesa y reaccion en cadena de la polimerasa (PCR). La expresión de citoquinas pro-inflamatorias/anti-inflamatorias y quimioquinas, fueron medidas por PCR en tiempo real. La expresión de citoquinas pro-inflamatorias/anti-inflamatorias y quemoquinas, fueron medidas por PCR en tiempo real. RESULTADOS: En las variables epidemiológicas y clínicas, los datos fueron similares en ambos grupos. Al comparar el grupo GM+ con el grupo GM-, resulta claro que, aunque las diferencias, en general, no son significativas, las citoquinas proinflamatorias están elevadas tanto en sangre materna como placentaria, las antiinflamatorias están elevadas en la madre y reducidas en la placenta, y las quimioquinas están reducidas en ambos compartimentos, excepto la MCP-1 que está elevada en ambos. CONCLUSIÓN: Los resultados parecen estar fuertemente afectados por la cantidad pequeña de mujeres con MG por P. vivax en el parto. Es necesario adelantar estudios adicionales con más mujeres tanto en esta región como en otros lugares.

Induction of transmission-blocking immunity in Aotus monkeys by vaccination with a Plasmodium vivax clinical grade PVS25 recombinant protein.

Aotus monkeys were used to determine the immunogenicity of Pvs25 protein expressed in the zygote/ookinete surface. Animals were immunized in three times with 100 microg of Pvs25 formulated in Montanide ISA-720. Antibodies to Pvs25 detected by an enzyme-linked immunosorbent assay appeared by day 30 after the first immunization, with a peak of antibodies levels on day 150. These antibodies were still detectable on day 300. Plasma samples on day 150 from experimental group were able to completely block the development of the parasite in Anopheles albimanus mosquitoes artificially fed with human isolates of Plasmodium vivax. Immunized Aotus monkeys were infected with blood forms of the P. vivax Salvador I strain and no boosting effect of blood infection on titers of antibodies to Pvs25 was observed despite the presence of infective gametocytes. In conclusion, Pvs25 protein formulated in Montanide ISA-720 induces efficient and long-lasting transmission-blocking antibodies that cannot be boosted by parasite infection.

Plasmodium vivax: transmission-blocking immunity in a malaria-endemic area of Colombia.

Plasmodium vivax transmission-blocking activity was assessed in sera from acutely infected patients from a malaria-endemic area in Colombia. We measured reduction in the number of oocysts that developed in the midguts of Anopheles albimanus mosquitoes artificially fed with blood from these patients. Of 88 mosquito batches that developed infections when parasites were mixed with normal AB human serum, one-third (36.4%) showed full transmission-blocking activity (>or= 90% inhibition) when mixed with autologous sera, 29.6% showed partial activity (50-89%), 17.0% did not block transmission (0-50%), and 17% did not enhance transmission. Transmission-blocking activity correlated with antibody titer by an immunofluorescent antibody test and decreased with the serial dilution of the sera. This activity disappeared at a 1:4 dilution in most sera tested. Afro-Colombian individuals showed lower activity than other ethnic groups and febrile patients produced stronger inhibition than those without fever.