Viable Leishmania parasites in the absence of an in vitro IFN-γ response in asymptomatic carriers

ABSTRACT Asymptomatic infection (the absence or inapparent signs and symptoms) has been observed in many endemic areas of leishmaniasis, however, little is known about the parasitological and immunological factors associated with this type of infection. This study aimed to identify the in vitro expression of IFN-γ in asymptomatic carriers of viable Leishmania parasites. Asymptomatic infection was identified using the Montenegro skin test in an at-risk population from Yucatan, Mexico. Parasite viability was evinced in the blood by 7SL RNA transcripts amplification. The expression of mRNA IFN-γ was analyzed in peripheral blood mononuclear cells stimulated with soluble Leishmania antigen, using RT-qPCR. Parasite viability was observed in 33.3 % (5/15) of asymptomatic subjects. No differences were found in the expression of IFN-γ between asymptomatic and healthy subjects, and no correlation was found between the presence of viable parasites and the expression of IFN-γ. This study demonstrates the persistence of Leishmania parasites in the absence of an in vitro IFN-γ response in asymptomatic carriers from Mexico.

Prevalencia de infección por Chlamydia trachomatis y relación con el perfil de conductas sexuales en adolescentes y mujeres jóvenes de la Provincia de Osorno, Chile

Introducción: La infección por Chlamydia trachomatis es la ITS bacteriana más frecuente del mundo. En el cervix se presenta mayormente de forma asintomática y afecta especialmente a mujeres jóvenes y adolescentes. Puede producir daño permanente en el tracto reproductor femenino, se asocia a parto prematuro, infecciones neonatales transmitidas vía vertical y mayor riesgo de adquirir otras ITS como VIH Y VPH. Por estos motivos se han establecido estrategias de tamizaje para detectar y tratar precozmente la infección asintomática por C. trachomatis en diferentes países. En nuestro país no contamos con un programa nacional de tamizaje. Objetivo: Determinar la prevalencia de infección asintomática por Chlamydia trachomatis en mujeres entre 12 y 21 años de la Provincia de Osorno, Región de Los Lagos, Chile. Pacientes y Métodos: Se desarrolló un estudio de diseño transversal con una cohorte única de mujeres adolescentes y jóvenes consultantes en el Policlínico de Alto Riesgo Obstétrico y de Ginecología Infantil y Adolescente, del Hospital Base de Osorno, entre enero de 2019 y enero 2020. Se determinó el estado de infección asintomática mediante RPC en tiempo real para C. trachomatis. Se realizó una encuesta a fin de determinar características demográficas, hábitos y conductas sexuales de las pacientes estudiadas. Resultados: Fueron reclutadas 124 mujeres entre 12 a 21 años de edad, de las cuales, 36 (29,3%) se encontraban embarazadas al momento del estudio. La prevalencia de infección asintomática por C. trachomatis fue de 14/124 (11,3%). En las mujeres gestantes se encontraron 6/36 (16,7%) casos positivos de infección por C. trachomatis y 8/88 (9,1%) en las no gestantes. Existe una mayor frecuencia de infección asintomática a menor edad de inicio de actividad sexual (33,3% en aquellas que inician entre 11-12 años vs. 16,2% en las que inician entre 1314 años, 7,4% entre 15-16 y 8% entre 17-21 años; p < 0,05). Esta tendencia no fue observada al comparar el estado de infección con el tiempo de vida sexual activa. Sólo 15,7% de las pacientes utilizó preservativo en todas sus relaciones sexuales. Discusión: La infección asintomática por C. trachomatis es frecuente en las mujeres adolescentes y jóvenes sexualmente activas. Las pacientes con inicio más temprano de la actividad sexual coital (bajo 13 años de edad) podrían estar en mayor riesgo. Se requiere con urgencia establecer la frecuencia nacional de infección para desarrollar una estrategia sanitaria para su pesquisa y manejo oportuno en nuestro país.

Background: Chlamydia trachomatis infection is the world most common bacterial STI. At uterine cervix it presents mostly asymptomatically and especially affects young women and adolescents. It can cause permanent damage to the female reproductive tract and is associated with premature birth, connatal infections and increased risk of acquiring other STIs such as HIV and HPV. For these reasons, other countries have established screening strategies to detect and treat asymptomatic C. trachomatis infection. Our country don't have a national screening program. Aim: To determine the prevalence of C. trachomatis asymptomatic infection in adolescent and young women in Osorno province, Los Lagos Region, Chile. Methods: A crosssectional study was performed in adolescent and young women who consult at Hospital Base Osorno in the MaternoFetal and PediatricAdolescent Gynecology ambulatory clinics, between January 2019 and January 2020. The status of asymptomatic infection was determined by PCR for C. trachomatis. A survey was carried out to determine the demographic characteristics, habits and sexual behaviors. Results: 124 women between 12 and 21 years of age were recruited, of which 36 (29,3%) were pregnant at the time of the study. The prevalence of asymptomatic infection by C. trachomatis was 11.3.%. In pregnant women, there were 6/36 (16.7%) positive cases for C. trachomatis and 8/88 (9.1%) in nonpregnant women. We found a higher frequency of asymptomatic infection at younger age of first sexual intercourse (33% in adolescents at 11-12 years old vs. 16.2% at 13-14, 7.4% at 15-16 and 8% at 17-21; p<0.05). Only 15.7% of the patients utilized condoms in all their intercourses. Discussion: Asymptomatic C. trachomatis infection is common in adolescent and young women, with a higher risk in those who onset sexual activity at an early age (less than 13 years old). It is urgently required to determine the national frequency of asymptomatic C. trachomatis infection to develop a national strategy for screening and timely treatment.

Clinical characteristics of asymptomatic infection of brucellosis / 中华地方病学杂志

Objective:To analyze the clinical characteristics of asymptomatic infection of brucellosis, in order to provide reference for prevention and treatment of brucellosis.Methods:Retrospective analysis was used to collect the clinical data of patients with brucellosis asymptomatic infection and confirmed cases admitted to the 940th Hospital of Joint Logistics Support Force of Chinese PLA from 2017 to 2021, and the demography characteristics, clinical manifestations and laboratory test results were analyzed.Results:The results showed that a total of 18 cases of asymptomatic infection and 85 confirmed cases of brucellosis were included, and there was no statistically significant difference in age, gender, occupation and ethnicity distribution between the two groups ( F = 7.09, χ 2 = 0.74, 4.02, 0.55, P = 0.295, 0.785, 0.327, 1.000). The 18 cases of asymptomatic infection of brucellosis were found through screening in key populations, and no clinical symptoms or abnormal imaging signs were observed. The clinical symptoms of 85 confirmed cases were mainly muscle and joint pain, fever, sweating, fatigue, and low back pain; and the imaging manifestations were mainly arthritis, splenomegaly, and spondylitis. The median percentage of eosinophils (0.70%, 1.40%), percentage of basophils (3.05%, 0.40%), C-reactive protein (1.62, 4.62 mg/L), erythrocyte sedimentation rate (1.00, 11.00 mm/h), and antibody titer of serum agglutination test (1 ∶ 100, 1 ∶ 200) showed statistically significant differences between asymptomatic infection and confirmed cases of brucellosis ( Z = - 2.97, - 5.11, - 3.49, - 3.21, - 3.50, P = 0.003, 0.001, 0.001, 0.001, 0.007). Conclusions:There is a difference in the composition of granulocytes between asymptomatic infection and confirmed cases of brucellosis, and the level of inflammatory response indicators is lower than that of confirmed cases. Regular seroepidemiological surveys among key populations can help screen for asymptomatic infection of brucellosis.

Adherencia a las recomendaciones de prevención de la sepsis neonatal temprana asociada a la colonización por Streptococcus agalactiae en una institución de referencia en Bogotá, Colombia, 2019 / Adherence to recommendations for preventing early neonatal sepsis associated with Streptococcus agalactiae colonization in a referral center in Bogotá, Colombia, 2019

RESUMEN Objetivos: Evaluar la adherencia a las recomendaciones de tamización para la prevención de la sepsis neonatal, describir la prevalencia de colonización por estreptococo del grupo B y los desenlaces perinatales asociados a la colonización por esta bacteria. Materiales y métodos: Estudio de cohorte retrospectiva que incluyó gestantes a término y sus recién nacidos, en una clínica universitaria privada de alta complejidad en Bogotá, entre el 1 de julio y el 31 de diciembre de 2019. Se evaluó la adherencia a la tamización y a la profilaxis antibiótica intraparto para las gestantes colonizadas con EGB, la prevalencia de colonización y los desenlaces perinatales adversos tempranos. Resultados: Se incluyeron 1.928 mujeres. La adherencia a la tamización fue de 68,0 % (IC 95 %: 66-70,1), a la administración de antibióticos intraparto de 87,9 % (IC 95 %: 87,8 -88), pero hubo uso no indicado de antibióticos en 14,7 % de mujeres para una adherencia final a profilaxis antibiótica de 86,3 %. La prevalencia de colonización por EGB fue 12,5 % (IC 95 %: 10,7-14,3), la incidencia de hospitalización neonatal fue de 27,5 % (IC 95 %: 16,3-33,7); no hubo casos de mortalidad ni sepsis neonatal temprana atribuibles al estado de tamización, colonización o profilaxis antibiótica para EGB. Conclusiones: Se requieren nuevos estudios en otras instituciones para determinar la adherencia a esta guía, en especial en aquellas regiones que atienden usuarias adscritas al régimen subsidiado, con cobertura a la población más vulnerable, así como nuevos estudios poblacionales de prevalencia de EGB y costo-efectividad de la estrategia de tamización universal en comparación con la profilaxis antibiótica basada en factores de riesgo.

ABSTRACT Objectives: To assess adherence to screening recommendations for the prevention of neonatal sepsis, and describe the prevalence of colonization by Group B streptococcus (GBS) as well as the perinatal outcomes associated with colonization by this bacterium. Material and methods: Retrospective cohort study that included pregnant women at term and their newborns, seen at a private high-complexity clinic in Bogota, between July 1 and December 31, 2019. Adherence to screening and intrapartum antibiotic prophylaxis in pregnant women colonized with group B streptococcus, as well as the prevalence of colonization and early adverse perinatal outcomes were assessed. Results: Overall, 1928 women were included. Adherence to screening was 68.0 % (95 % CI: 66-70.1) and 87.9 % to intrapartum antibiotic administration (95 % CI: 87.8-88); non-indicated use of antibiotics occurred in 14.7 % of the women, for 86.3 % final adherence to antibiotic prophylaxis. The prevalence of GBS colonization was 12.5 % (95 % CI: 10.7-14.3); the incidence of neonatal hospitalization was 27.5 % (95 % CI: 16.3-33.7). There were no cases of mortality or early neonatal sepsis attributable to screening status, colonization or prophylactic antibiotics for GBS. Conclusions: Additional studies in other centers are required in order to determine adherence to this guideline, particularly in those that receive users affiliated to the subsidized regime which covers the most vulnerable population. Also, new population studies of GBS prevalence and cost-effectiveness of universal screening compared to risk factor-based antibiotic prophylaxis are needed.

Traditional Chinese medicine treatment of asymptomatic infection of SARS-CoV-2 / 中华危重病急救医学

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been infected rapidly and is generally susceptible to population. Moreover, it has become the most serious public health problem in the world. In the process of coronavirus disease 2019 (COVID-19) treatment, the traditional Chinese medicine (TCM) intervention has achieved positive efficacy and which is widely recognized. However, the COVID-19 epidemic is still very serious, especially due to the characteristics of asymptomatic infection such as concealment, limitations and subjective symptoms, which has increased the difficulty of prevention and control. In view of asymptomatic infection, isolation is the main management. There is little mention of specific treatment options in each version of COVID-19 treatment plan. Through systematic study of TCM theory, we explored the way of diagnosis and treatment of asymptomatic infections. Based on the theory of latent evil, clearing away latent pathogens to truncate the course of disease and reduce the incidence. Based on the theory of prevention of disease, strengthen the lung and stomach to protect the place from pathogen and prevent the transmission of disease evil. It is supplemented by accurate treatment according to individual, timing and local conditions, in order to provide reference for the treatment of asymptomatic infection.

Blocking effect of SARS-CoV-2 vaccines on virus transmission: current situation and prospect / 中华微生物学和免疫学杂志

SARS-CoV-2 vaccines are effective in preventing COVID-19, but their efficacy in blocking virus transmission is controversial. Although SARS-CoV-2 vaccines can reduce the sources of infection and the possibility of secondary transmission from breakthrough infection cases, their effectiveness wanes over time. Moreover, the emergence of variants with stronger transmissibility and immune escape ability also poses huge challenges to the effectiveness of SARS-CoV-2 vaccines in blocking virus transmission. Therefore, ending the COVID-19 pandemic still requires the continuous research and development of new vaccines as well as the adoption of effective prevention and control measures.

Molecular detection of SARS-CoV-2 being challenged by virus variation and asymptomatic infection / 药物分析学报

Coronavirus disease 2019 (COVID-19) has been a pandemic for more than a year.With the expanding second wave of the pandemic in winter,the continuous evolution of SARS-CoV-2 has brought new issues,including the significance of virus mutations in infection and the detection of asymptomatic infection.In this review,we first introduced several major SARS-CoV-2 mutations since the COVID-19 outbreak and then mentioned the widely used molecular detection techniques to diagnose COVID-19,primarily focusing on their strengths and limitations.We further discussed the effects of viral genetic variation and asymptomatic infection on the molecular detection of SARS-CoV-2 infection.The review finally sum-marized useful insights into the molecular diagnosis of COVID-19 under the special situation being challenged by virus mutation and asymptomatic infection.

Zika virus infection and transfusion safety / 中国输血杂志

Zika virus(ZIKV) is an arbovirus transmitted mainly by mosquitoes. ZIKV infection usually causes mild self-limiting disease, and most of the infected patients only developed relatively mild symptoms which were often easily overlooked. However, serious damage of the central nervous system is observed in a few of the infected patients, and microcephaly of embryos and fetuses in pregnant women infected by ZIKV has attracted wide attention in recent years. Although there is a high proportion of asymptomatic infection and a high incidence of viremia, ZIKV has not been included in the routine pathogen screening before blood donation in China yet, and there is a risk of transmission through blood transfusion. This article briefly introduces the biological characteristics, epidemic characteristics, and pathogenic mechanisms of ZIKV,, and discusses ZIKV infection and the safety of blood transfusion.

Apoptosis de neutrófilos en la infección asintomática por Virus de la Inmunodeficiencia Humana / Neutrophil apoptosis in asymptomatic Human Immunodeficiency Virus infection

En los últimos años se ha determinado que los neutrófilos son células altamente versátiles y sofisticadas, cuyas funciones van mucho más allá de la eliminación de los microorganismos. En la infección con el Virus de Inmunodeficiencia Humana (HIV), si bien el papel de los neutrófilos no está totalmente caracterizado, actualmente está claro que la relación entre los neutrófilos y el virus es mucho más compleja de lo que se pensaba. Los objetivos de este trabajo fueron evaluar en pacientes con infección asintomática, y sin tratamiento antirretroviral, el efecto de la infección por el HIV sobre la muerte celular de los neutrófilos y la expresión de receptores de superficie. En pacientes seropositivos sin tratamiento hubo un aumento de la apoptosis temprana de los neutrófilos en relación a los grupos controles. Esta apoptosis aumentada no depende de la activación de la vía extrínseca o intrínseca. En estos pacientes hubo un aumento de la expresión de TLR2 que, unido al aumento de la apoptosis temprana, podría ser indicativo de un fenotipo activado de los neutrófilos. En conclusión, este trabajo aporta información sobre aspectos relacionados con la apoptosis de los neutrófilos en estadios tempranos de la infección por HIV, contribuyendo así a una mayor comprensión acerca del efecto de este virus sobre componentes de la respuesta inmune innata.

In recent years it has been determined that neutrophils are highly versatile and sophisticated cells whose functions go far beyond the elimination of microorganisms. In Human Immunodeficiency Virus (HIV) infection, the role of neutrophils is not fully characterized but it is now clear that the relationship between neutrophils and HIV is much more complex than previously thought. The aims of this study were to evaluate the effect of HIV infection on neutrophil cell death and the expression of surface molecules on neutrophils in patients with asymptomatic infection and without antiretroviral treatment (ART). In HIV seropositive patients without antiretroviral therapy there was an increase in the early apoptosis of neutrophils in relation to the control groups. This increased apoptosis does not depend on the activation of the extrinsic or intrinsic pathway. In these patients there was an increase in the expression of TLR2 which, together with the increase of early apoptosis, could be indicative of an activated phenotype of neutrophils. In conclusion, this study provides information on aspects related to the apoptosis of neutrophils in early stages of HIV infection and therefore contributes to a better understanding of the effect of this virus on components of the innate immune response.

Nos últimos anos, determinou-se que os neutrófilos são células altamente versáteis e sofisticadas, cujas funções vão muito além da eliminação dos microrganismos. Na infecção pelo HIV, embora o papel dos neutrófilos não esteja totalmente caracterizado, atualmente fica bem claro que a relação entre os neutrófilos e o vírus é muito mais complexa do que se pensava anteriormente. Os objetivos deste trabalho foram avaliar em pacientes com infecção assintomática, e sem tratamento antirretroviral, o efeito da infecção pelo HIV na morte celular dos neutrófilos e a expressão de receptores de superfície. Nos pacientes soropositivos sem tratamento, houve um aumento da apoptose precoce dos neutrófilos em relação aos grupos controle.Esta apoptose aumentada não depende da ativação da via extrínseca ou intrínseca. Nestes pacientes, houve um aumento da expressão de TLR2 que, juntamente com o aumento da apoptose precoce, poderia ser indicativo de um fenótipo ativado dos neutrófilos. Em conclusão, este trabalho fornece informações sobre aspectos relacionados com a apoptose dos neutrófilos em estágios precoces da infecção pelo HIV, contribuindo desse modo para uma maior compreensão sobre o efeito deste vírus nos componentes da resposta imune inata.

Association between asymptomatic sexually transmitted infections and high-risk human papillomavirus in cervical lesions / 西安交通大学学报(医学版)

Objective To determine the association of asymptomatic sexually transmitted infections (STIs) with high-risk human papillomavirus (hrHPV) in cervical squamous intraepithelial lesions and neoplasms. Methods From July 2017 to July 2018, 320 hrHPV-positive and 160 hrHPV-negative women in The First Affiliated Hospital of Xi'an Jiaotong University were divided into normal+low-grade squamous intraepithelial lesion (LSIL) and high-grade squamous intraepithelial lesion (HSIL)+ invasive cervical cancer (ICC) subgroups, respectively, based on their pathological cervical lesion grades. Cervical brush specimens including Ureaplasma urealyticum (UU) and its serotypes, Mycoplasma hominis (MH), Mycoplasma genitalium (MG), Chlamydia trachomatis (CT), and hrHPV were amplified and hybridized using PCR kits (Hybribio Biochemistry Co., Ltd.). The differences between groups were examined by the chi-squared test, continuity correction and Logistic regression. Results The overall infection (at least one of the non-hrHPV pathogens was positive) rates of the two groups were 62.5% and 59.4%, which were not significantly different. The prevalence of UU was the highest. The prevalence of UU serotype 14 (Uup14) and MH was associated with hrHPV (P=0.003, P=0.005, respectively), but not with certain hrHPV genotypes or with single or multiple genotypes. Compared with cases of normal+LSIL, cases of HSIL+ICC had significantly different Uup14 infection rates (OR: 12.579, 95% CI: 3.638-43.497, P<0.001) in the positive group. In hrHPV-negative cases, there were obvious differences in Uuu and Uup1 infections based on different cervical lesion types (OR: 11.646, 95% CI: 1.493-90.850, P=0.019; OR: 7.474, 95% CI: 1.140-49.015, P=0.036). Conclusion Asymptomatic STIs in female lower reproductive tract are widespread. Uup14 may increase the risk of HSIL+ICC when hrHPV is positive. Uuu and Uup1 cause an increased risk of HSIL+ICC without hrHPV.

Asymptomatic Middle East Respiratory Syndrome coronavirus infection using a serologic survey in Korea / 한국역학회지

OBJECTIVES: The rates of asymptomatic infection with Middle East Respiratory Syndrome (MERS) coronavirus vary. A serologic study was conducted to determine the asymptomatic MERS infection rate in healthcare workers and non-healthcare workers by exposure status.METHODS: Study participants were selected from contacts of MERS patients based on a priority system in 4 regions strongly affected by the 2015 MERS outbreak. A sero-epidemiological survey was performed in 1,610 contacts (average duration from exposure to test, 4.8 months), and the collected sera were tested using an enzyme-linked immunespecific assay (ELISA), immunofluorescence assay (IFA), and plaque reduction neutralization antibody test (PRNT). Among the 1,610 contacts, there were 7 ELISA-positive cases, of which 1 exhibited positive IFA and PRNT results.RESULTS: The asymptomatic infection rate was 0.060% (95% confidence interval, 0.002 to 0.346). The asymptomatic MERS case was a patient who had been hospitalized with patient zero on the same floor of the hospital at the same time. The case was quarantined at home for 2 weeks after discharge, and had underlying diseases, including hypertension, angina, and degenerative arthritis.CONCLUSIONS: The asymptomatic infection was acquired via healthcare-associated transmission. Thus, it is necessary to extend serologic studies to include inpatient contacts who have no symptoms.

Asymptomatic Middle East Respiratory Syndrome coronavirus infection using a serologic survey in Korea / 한국역학회지

OBJECTIVES: The rates of asymptomatic infection with Middle East Respiratory Syndrome (MERS) coronavirus vary. A serologic study was conducted to determine the asymptomatic MERS infection rate in healthcare workers and non-healthcare workers by exposure status. METHODS: Study participants were selected from contacts of MERS patients based on a priority system in 4 regions strongly affected by the 2015 MERS outbreak. A sero-epidemiological survey was performed in 1,610 contacts (average duration from exposure to test, 4.8 months), and the collected sera were tested using an enzyme-linked immunespecific assay (ELISA), immunofluorescence assay (IFA), and plaque reduction neutralization antibody test (PRNT). Among the 1,610 contacts, there were 7 ELISA-positive cases, of which 1 exhibited positive IFA and PRNT results. RESULTS: The asymptomatic infection rate was 0.060% (95% confidence interval, 0.002 to 0.346). The asymptomatic MERS case was a patient who had been hospitalized with patient zero on the same floor of the hospital at the same time. The case was quarantined at home for 2 weeks after discharge, and had underlying diseases, including hypertension, angina, and degenerative arthritis. CONCLUSIONS: The asymptomatic infection was acquired via healthcare-associated transmission. Thus, it is necessary to extend serologic studies to include inpatient contacts who have no symptoms.

Visceral leishmaniasis: An immunological viewpoint on asymptomatic infections and post kala azar dermal leishmaniasis

Elimination of visceral leishmaniasis is a priority programme in Indian subcontinent. The World Health Organization has set a new target to eliminate kala-azar by the year 2020 as previous target elimination year (2015) has passed. The elimination programme has successfully curbed the rate of infection in endemic regions; however, there are still few challenges in its route. The current drug control regime is extremely limited and comprises only two (amphotericin B and miltefosine) drugs, which are also susceptible for parasites resistance. Moreover, these drugs do not produce sterile cure, and cured patients may develop post kala-azar dermal leishmaniasis even after a decade of cure leaving behind a potent source of parasitic reservoirs for further disease transmission. A significant proportion of endemic population remain seropositive but aymptomatic for many years without any clinical symptom that serve as latent parasitic reservoirs. The lack of tools to identify live parasites in asymptomatic infections and there association in disease transmission, parameters of sterile cure along with post kala-azar dermal leishmaniasis progression remain a major threat in its elimination. In this review, we discuss the potential of host immune inhibitory mechanisms to identify immune correlates of protective immunity to understand the mystery of asymptomatic infections, sterile cure and post kala azar dermal leishmaniasis.

Features of human cytomegalovirus UL146 gene in asymptomatic children / 中华微生物学和免疫学杂志

Objective To investigate the polymorphisms of human cytomegalovirus ( HCMV ) UL146 gene in asymptomatic children. Methods Urine samples were collected from 47 asymptomatic chil-dren who were positive for HCMV DNA. PCR was performed to amplify the open reading frame ( ORF) of UL146 gene. Positive bands were sequenced and variations in UL146 gene were analyzed by using bioinfor-matics software. Results Seventeen samples were successfully amplified and sequenced. Variations spread all over the sequence of UL146 gene and the variability in nucleotide and amino acid sequences ranged from 0％ to 42. 5％ and 0％ to 67. 7％ respectively. Compared with the Towne strain, there was diversity in sig-nal sequence and C-terminal region. Phylogenetic analysis indicated that UL146 in the 17 asymptomatic chil-dren belonged to four genotypes, which were G1, G8, G9 and G11. Forms of post-translational modification varied greatly among the four genotypes, while the important functional region of ELRCXC chemokine was highly conservative. Secondary structure prediction showed that random-coli conformation was the predomi-nant structure of active proteins. Isoelectric point ( PI) and molecular weight ( MW) were dissimilar among the four genotypes. Conclusion HCMV UL146 gene in asymptomatic children was hypervariable in both nucleotide sequence and amino acid structure. However, the important functional region was highly con-served. The predominant genotypes of UL146 in these children were G1, G8, G9 and G11, and the geno-type distribution in them showed no significant difference with previous findings in children with symptomatic HCMV infection.

Features of human cytomegalovirus UL146 gene in asymptomatic children / 中华微生物学和免疫学杂志

Objective To investigate the polymorphisms of human cytomegalovirus ( HCMV ) UL146 gene in asymptomatic children. Methods Urine samples were collected from 47 asymptomatic chil-dren who were positive for HCMV DNA. PCR was performed to amplify the open reading frame ( ORF) of UL146 gene. Positive bands were sequenced and variations in UL146 gene were analyzed by using bioinfor-matics software. Results Seventeen samples were successfully amplified and sequenced. Variations spread all over the sequence of UL146 gene and the variability in nucleotide and amino acid sequences ranged from 0％ to 42. 5％ and 0％ to 67. 7％ respectively. Compared with the Towne strain, there was diversity in sig-nal sequence and C-terminal region. Phylogenetic analysis indicated that UL146 in the 17 asymptomatic chil-dren belonged to four genotypes, which were G1, G8, G9 and G11. Forms of post-translational modification varied greatly among the four genotypes, while the important functional region of ELRCXC chemokine was highly conservative. Secondary structure prediction showed that random-coli conformation was the predomi-nant structure of active proteins. Isoelectric point ( PI) and molecular weight ( MW) were dissimilar among the four genotypes. Conclusion HCMV UL146 gene in asymptomatic children was hypervariable in both nucleotide sequence and amino acid structure. However, the important functional region was highly con-served. The predominant genotypes of UL146 in these children were G1, G8, G9 and G11, and the geno-type distribution in them showed no significant difference with previous findings in children with symptomatic HCMV infection.

Asymptomatic infection with American cutaneous leishmaniasis: epidemiological and immunological studies

American cutaneous leishmaniasis (ACL) is a major public health problem caused by vector-borne protozoan intracellular parasites from the genus Leishmania, subgenera Viannia and Leishmania. Asymptomatic infection is the most common outcome after Leishmania inoculation. There is incomplete knowledge of the biological processes explaining the absence of signs or symptoms in most cases while other cases present a variety of clinical findings. Most studies of asymptomatic infection have been conducted in areas of endemic visceral leishmaniasis. In contrast, asymptomatic ACL infection has been neglected. This review is focused on the following: (1) epidemiological studies supporting the existence of asymptomatic ACL infection and (2) immunological studies conducted to understand the mechanisms responsible for controlling the parasite and avoiding tissue damage.

Immunoregulation in human malaria: the challenge of understanding asymptomatic infection

Asymptomatic Plasmodium infection carriers represent a major threat to malaria control worldwide as they are silent natural reservoirs and do not seek medical care. There are no standard criteria for asymptomaticPlasmodium infection; therefore, its diagnosis relies on the presence of the parasite during a specific period of symptomless infection. The antiparasitic immune response can result in reducedPlasmodium sp. load with control of disease manifestations, which leads to asymptomatic infection. Both the innate and adaptive immune responses seem to play major roles in asymptomatic Plasmodiuminfection; T regulatory cell activity (through the production of interleukin-10 and transforming growth factor-β) and B-cells (with a broad antibody response) both play prominent roles. Furthermore, molecules involved in the haem detoxification pathway (such as haptoglobin and haeme oxygenase-1) and iron metabolism (ferritin and activated c-Jun N-terminal kinase) have emerged in recent years as potential biomarkers and thus are helping to unravel the immune response underlying asymptomatic Plasmodium infection. The acquisition of large data sets and the use of robust statistical tools, including network analysis, associated with well-designed malaria studies will likely help elucidate the immune mechanisms responsible for asymptomatic infection.

Development and application of rapid molecular method for detection of as-ymptomatic infection of Leishmania / 中国血吸虫病防治杂志

Objective To develop a rapid molecular biological method for detection of the asymptomatic infection of Leish?mania. Methods Two pairs of primers named RV1?RV2 and K13A?K13B were selected to be the fast diagnosis primers since they were designed according to the conserved region of Leishmania kinetoplast DNA(kDNA)minicircles. The PCR amplifica?tion products of Leishmania donovani promastigote from Shandong Province were sequenced to compare their conservatism. The method was applied to detect 105 venous blood samples from healthy home canine and 7 venous blood samples from home canine suffered from Kala?azar in Heishui County of Sichuan Province,and 75 venous blood samples from susceptible population(no leishmaniasis symptoms)and 7 venous blood samples from patients in Xinjiang Kashi area in order to verify the feasibility and accuracy of the method. Results The size of PCR products was consistent with the expected fragments with high conservative among Leishmania species. The positive rates of 105 home canine samples and 75 susceptible population samples were 37.14%(39/105)and 82.67%(62/75)rspectively,and the positive rates of home canine suffered from Kala?azar and patients were all 100%(7/7). Conclusion This rapid diagnosis method is suitable for detection of asymptomatic infection of Leishmania in Kala?azar endemic areas of China with high sensitive and specific,thus it has bright perspective to be used.

Seroprevalence of Helicobacter pylori Infection among Asymptomatic Children in Lagos, Nigeria.

Aim: Helicobacter pylori infection is mainly acquired during childhood and is strongly linked with peptic ulcer disease. This study determines the seroprevalence of Helicobacter pylori infection among school children in Lagos, Nigeria. Place of Study: Alimosho and Ajeromi Local Government Areas of Lagos state, Nigeria between months March to September 2014. Methodology: 195 asymptomatic children of aged 2-16 attending public health facility in selected Local Government in Lagos, Nigeria were recruited for the study with descriptive questionnaire. Blood samples of 5 ml were collected into plain bottle and sera obtained were analysed for Helicobacter pylori Immunoglobulin G using DiaSpot H. pylori kit. Results: Of the 195 children examined for H. pylori IgG, 72.3% were seropositive while highest rate of 72.7% seroprevalence was recorded among children aged 5-7 years. Of seropositive observed among children aged 5-7 years, 37.5% and 62.5% were male and female respectively, while seropositive rate among children age 8-10 years, 51.3% were female and 48.7% male (p=0.055). Seroprevalence rate of 70.1% was observed among the children living in a house with population of 6 -7 people (p=0.076) while significant value of 69.1% and 76.6% were recorded among the children whose parents are traders and middle class employees respectively (p<0.05). Households with no regular potable water supply (never) have higher rate of 70.3% seroprevalence and 73.2% rate was observed among those that sometimes have water for their drinking and domestic use. Seropositive children of 72.5% sometimes buy food from elsewhere while only 73.2% seropositive always buy food from street vendors or other sources outside their home Conclusion: It could be deduced that while H. pylori is acquired early in life, infection can be asymptomatic and poor standards of living and socioeconomic status can contribute to early infections.

Variation in haematological parameters in children less than five years of age with asymptomatic Plasmodium infection: implication for malaria field studies

During the season of high malaria transmission, most children are infected by Plasmodium, which targets red blood cells (RBCs), affecting haematological parameters. To describe these variations, we examined the haematological profiles of two groups of children living in a malaria-endemic area. A cross-sectional survey was conducted at the peak of the malaria transmission season in a rural area of Burkina Faso. After informed consent and clinical examination, blood samples were obtained from the participants for malaria diagnosis and a full blood count. Of the 414 children included in the analysis, 192 were not infected with Plasmodium, whereas 222 were asymptomatic carriers of Plasmodium infection. The mean age of the infected children was 41.8 months (range of 26.4-57.2) compared to 38.8 months (range of 22.4-55.2) for the control group (p = 0.06). The asymptomatic infected children tended to have a significantly lower mean haemoglobin level (10.8 g/dL vs. 10.4 g/dL; p < 0.001), mean lymphocyte count (4592/µL vs. 5141/µL; p = 0.004), mean platelet count (266 x 103/µL vs. 385 x 103/µL; p < 0.001) and mean RBC count (4.388 x 106/µL vs. 4.158 x 106/µL; p < 0.001) and a higher mean monocyte count (1403/µL vs. 1192/µL; p < 0.001) compared to the control group. Special attention should be applied when interpreting haematological parameters and evaluating immune responses in asymptomatic infected children living in malaria-endemic areas and enrolled in vaccine trials.