Detection Of Asymptomatic Infection Research Articles

Rapid, sensitive, and convenient detection of Plasmodium falciparum infection based on CRISPR and its application in detection of asymptomatic infection

Rapid and convenient detection of the Plasmodium in clinically diagnosed individuals and asymptomatically infected populations is essential for global malaria eradication, especially in malaria-endemic African countries where medical equipment and professionals are relatively deficient. Here, we described a CRISPR-based diagnostic for the detection of Plasmodium falciparum, the deadliest and most prevalent species of malaria parasite in Africa, via lateral flow strip readout without the need of nucleic acid extraction. The assay exhibited 100% sensitivity on clinical samples (5 P falciparum) and significant consistency with qPCR test on asymptomatic infection samples (49 P falciparum and 51 non-P. falciparum, Kappa=0.839). An artemisinin-resistant P. falciparum strain and 4 other laboratory-cultured strains can also be detected through this assay, whereas no cross-reactivity with Plasmodium vivax was observed. A 0.001% parasitaemia (corresponding to ∼60 parasites/μL) below the “low parasite density” test threshold (200 parasites/µL) is detectable. Our study demonstrated that direct malaria detection using whole blood on the spot and the detection of both clinical and asymptomatic infections of P. falciparum are feasible. This method is expected to be employed for clinical testing and large-scale community screening in Africa and possibly other places, contributing to the accurate diagnosis and control of malaria.

High-throughput quantitation of SARS-CoV-2 antibodies in a single-dilution homogeneous assay

SARS-CoV-2 emerged in late 2019 and has since spread around the world, causing a pandemic of the respiratory disease COVID-19. Detecting antibodies against the virus is an essential tool for tracking infections and developing vaccines. Such tests, primarily utilizing the enzyme-linked immunosorbent assay (ELISA) principle, can be either qualitative (reporting positive/negative results) or quantitative (reporting a value representing the quantity of specific antibodies). Quantitation is vital for determining stability or decline of antibody titers in convalescence, efficacy of different vaccination regimens, and detection of asymptomatic infections. Quantitation typically requires two-step ELISA testing, in which samples are first screened in a qualitative assay and positive samples are subsequently analyzed as a dilution series. To overcome the throughput limitations of this approach, we developed a simpler and faster system that is highly automatable and achieves quantitation in a single-dilution screening format with sensitivity and specificity comparable to those of ELISA.

A review on Trichomonas vaginalis infections in women from Africa.

BackgroundTrichomoniasis is the most common sexually transmitted infection (STI) with an estimated annual incidence of 276.4 million cases globally and about 30 million cases in sub-Saharan Africa. Trichomoniasis has been found to be associated with various health complications including pelvic inflammatory disease (PID), significant pregnancy complications, cervical cancer, prostatitis, infertility and the acquisition of human immunodeficiency virus (HIV).AimDespite being a highly prevalent infection in the African continent, there is no review article published that solely focusses on Trichomonas vaginalis (T. vaginalis) infections in women from Africa. This review aims to fill this gap in the literature.MethodAn electronic search of online databases was used to identify and extract relevant research articles related to the epidemiology, health complications and treatment associated with T. vaginalis in women from Africa.ResultsWithin the African continent, South Africa has reported the highest prevalence rate for this infection. A combination of sociodemographic, behavioural and biological factors has been shown to be associated with infection. Trichomonas vaginalis infection is associated with the acquisition of HIV, cervical cancer and PIDs in various female populations across the continent. Emerging patterns of resistance to metronidazole have been reported in women from South Africa. Currently, there is no effective vaccine against this pathogen despite efforts at vaccine development.ConclusionBased on the high prevalence and health consequences associated with T. vaginalis, there is a need for improved screening programmes that will lead to early diagnosis, detection of asymptomatic infections and effective treatment regimens.

Lessons from New Zealand's COVID-19 outbreak response

Lessons from New Zealand's COVID-19 outbreak response

Exhaled nitric oxide in diagnostics and monitoring of lung diseases

In recent 10 years there has been an explosion of interest in the analysis of breath constituents as a way of monitoring airway inflammation in lung diseases. Monitoring of inflammation may assist in differential diagnosis of lung diseases, assessment of their severity and response to appropriate treatment. Among these novel non-invasive methods, exhaled nitric oxide has been the most extensively studied. Its measurement has recently been standardized, and there are now commercially available nitric oxide analyzers. Concentration of exhaled nitric oxide is markedly elevated in asthma, and its elevation is positively related to the degree of eosinophilic airway inflammation, airway hyperresponsiveness and symptoms. Furthermore, evidence suggests that exhaled nitric oxide-driven asthma treatment provides more precise asthma control compared to conventional treatment protocols. With regard to other lung diseases, in chronic obstructive pulmonary disease exhaled nitric oxide may be useful in predicting steroid responsiveness, while in lung transplant recipients its measurement could contribute to the detection of asymptomatic infections and rejection processes.

High Prevalence of Congenital Trypanosoma cruzi Infection and Family Clustering in Salta, Argentina

Trypanosoma cruzi, the causative agent of Chagas' disease, is transmitted mainly by insect vectors, but congenital and transfusion-borne infections occasionally occur. The factors that are involved in transmission from mother to offspring are not well understood. The objective of this study was to study the presence of T cruzi infection in children who were born to infected mothers and in the children's siblings to evaluate the epidemiologic risk factors associated with congenital transmission of Chagas' disease. Congenital T cruzi infection was studied in 340 children who were born to chronically infected mothers in Salta, Argentina. Infection was detected in 31 children, who were selected for additional study as infected index cases (IIC). Of the 309 noninfected children, 31 were taken as noninfected index cases (NIIC). We compared the prevalence of congenital T cruzi transmission in the remaining siblings of the IIC and NIIC. Data and blood samples were collected in house-to-house visits. Diagnosis of infection was established mainly by serologic methods, indirect hemmagglutination, and enzyme-linked immunosorbent assay. The prevalence was 31.4% (32 of 102 children) for IIC siblings, whereas no infected siblings were found in families with NIIC (0 of 112). Clustering of congenital infection was found in 14 families, in which >1 child was infected. Second-generation congenital transmission (from grandmother to mother to newborn) was established in 4 families. The association among low weight at birth, prematurity, and congenital transmission was highly significant. An important observation was the absence of pathologic findings in a high proportion of infected children. The detection of asymptomatic infections was a consequence of population screening, as opposed to hospital-based diagnosis, for which symptomatic cases predominate. Congenital transmission was associated with the geographic origin of mothers: women from areas where insect vectors proliferate were less likely to give birth to infected offspring than women from areas under active vector control. Siblings of an infant infected with T cruzi are at high risk for infection themselves and, even in the absence of symptoms, should also be screened for infection. The findings of family clustering of infection and of second-generation congenital infection in vector-free areas suggest that new modalities of transmission, other than classic vector-borne spread, may occur both in endemic and in nonendemic areas.

Impact of Chlamydia trachomatis and HPV Infection Among Sexually Active Teenage Girls in Upper Silesia, Poland

In their paper published in J Korean Med Sci entitled Screening for Chlamydia and gonorrhea by strand displacement amplification in homeless adolescents attending youth shelters in Korea, Lee et al. demonstrated that the prevalence of Chlamydia trachomatis among homeless adolescents was 12.6% (1). They reported a higher rate (28.1%) of infection among sexually active adolescents than in a sexually inactive group. In our study, to recognize the global importance of sexually transmitted infections (STI) among teenage girls in Upper Silesia we investigated 48 non-pregnant, sexually active girls aged 16-19, living in an urban area, who paid a visit for periodical check-up during oral contraceptive use. The majority of the adolescents reported periodical mild pain in the lower abdominal area and an increased amount of mucous discharge. They also reported early first sexual unprotected intercourse (<16 yr of age) and more than three sexual partners. We used direct immunofluorescence assay for C. trachomatis antigen detection (Chlamydia Direct IF, bioMerieux, France) and obtained a high prevalence (27%) of C. trachomatis infection. C. trachomatis infection is the most common bacterial STI, however, up to 70% of such infections are asymptomatic (2). The detection of asymptomatic infection has an important epidemiological implication, because the main consequences (infertility, ectopic pregnancy, pelvic inflammatory disease, and perinatal infections) of symptomatic and asymptomatic infections are often identical. In regions where an early screening program for detection of C. trachomatis infection has been established, the prevalence of infection in women is low: among Norwegian girls aged between 16-19 yr C. trachomatis infection was confirmed only in 9% (3). Testing for C. trachomatis in teenage girls is not routinely performed in many countries (including Poland). Cook et al. (4) found that only one-third of physicians carries out C. trachomatis tests in asymptomatic, sexually active teenage women during a routine gynecologic examination. In our previous study (5) of 205 sexually active women aged 17-40, we demonstrated a significant decrease of C. trachomatis infection among women younger than 25. British authors described 12.1% chlamydial infections in the age group of girls aged 16-19, 8.8% in the age group 20-24, and only 7.5% in the group younger than 16 (6). It is well known that human papilloma virus (HPV) is a proliferative virus, replicating only in actively dividing cells. The coexistence of bacterial infection (including C. trachomatis) may potentiate the proliferation and replication (7, 8). Moreover, C. trachomatis infection may be a possible cofactor of HPV infection, playing a major role in the etiology of cervical intraepithelial neoplasia. For this reason in our study group of teenage girls we also detected HPV DNA in collected cervical brushes using the Hybrid Capture I HPV Assay (Digene Corp. Beltsville, MD, U.S.A.), with complimentary probes for low oncogenic (6/11/42/43/44) and high oncogenic types (16/18/31/33/35/45/51/52/56). The collected cervical swabs were also assessed using the 2001 Bethesda System. HPV DNA was detected only in 2 cases with a normal cytology. Low grade squamous intraepithelial lesions (LSIL) was described in 5 cases out of 48, all of which were HPV DNA-negative, however 4 were C. trachomatis-positive. The role of C. trachomatis in the development of cervical dysplasia is still controversial. Antilla et al. (9), and Koskela et al. (10) considered an independent role of C. trachomatis in pathogenesis of cervical intraepithelial dysplasia. Our results, obtained on a small group of girls in Upper Silesia, were concordant with the above conclusion, however, further studies on larger group of adolescent girls are required to confirm this hypothesis.

Screening for Tuberculosis-Reply

In Reply. —Dr Bayuk has correctly pointed out several of the current problems and debates concerning TB control among immigrants to the United States. Currently, 32% of all US TB cases occur among non—US-born persons. 1 The rate of TB disease among non—US-born children is 13 times the rate among US-born children. Most children immigrating through established channels get neither a tuberculin skin test nor a chest radiograph since children rarely have contagious TB. However, some of the children with undetected TB infection will develop contagious TB after arrival in the United States, often within 5 years of arrival and at higher than expected rates. 2 While most countries (all but the United States and the Netherlands) have relied on BCG vaccination to try to prevent TB, the United States has emphasized detection of asymptomatic infection and treatment with chemotherapy. Both approaches have severe limitations. The BCG vaccines have limited