Molecular and serological prevalence of Coxiella burnetii in bovine dairy herds in southern Chile: A PCR and ELISA-based assessment of bulk tank milk samples

Coxiella burnetii (C. burnetii) is a highly resilient zoonotic bacterium responsible for Q fever, a disease which occurs worldwide, with the exception of New Zealand. However, in Chile, the prevalence and impact of C. burnetii in cattle herds remain poorly understood due to limited research. This study aimed to assess the presence of C. burnetii in dairy cattle herds in southern Chile, using two diagnostic methods on bulk tank milk samples. The results of the study revealed a high prevalence of C. burnetii infection in the analyzed herds. Of the 271 milk tank samples tested, 76% (208/271, CI: 71.1-81.5) tested positive using ELISA, while 73% (200/271, CI: 68.0-78.8) tested positive using qPCR. These findings indicate a significant presence of C. burnetii in the cattle herds studied. Despite the high prevalence observed, no new Q fever outbreaks have been reported in the study area. This discrepancy highlights the need for further research to better understand the transmission dynamics, environmental factors, and livestock management practices associated with C. burnetii infection. These studies will contribute to the development of effective prevention and control strategies and promote public health regarding Q fever.

Highlights from the Tenth International Workshop on HIV Persistence during Therapy, December 13-16, 2022, Miami, Florida-USA

The International Workshop on HIV Persistence during Therapy provides a forum in which HIV/AIDS researchers gather to share the latest research findings related to viral reservoirs and cure. The Tenth Workshop, which was attended by over 400 delegates, extended over 4 days and comprised eight sessions covering topics from the basic science of viral persistence to therapeutic approaches to HIV cure. Furthermore, satellite sessions on the first day of the Conference featuring cure research endeavours being pursued by the Bill and Melinda Gates Foundation as well as those being coordinated under the National Institutes of Health Martin Delaney Collaboratory program, provided important updates on research advances being made in these initiatives. As with previous conferences, the International Workshop on HIV Persistence during Therapy is primarily abstract-driven with only one invited talk for each of the sessions. This format, therefore, increases the number of presentations from early-stage investigators. Furthermore, presentations by Community representatives illustrated approaches to creating cure research literacy with effective messaging for the Community. The following article offers a synopsis of the meeting sessions. Due to space constraints, some presentations may have only been briefly discussed. Nevertheless, the Workshop abstracts can be found online (https://www/sciencedirect.com/journal/journal-of-virus-eradication/vol/8/suppl/S).

A signature of circulating microRNAs predicts the response to treatment with FOLFIRI plus aflibercept in metastatic colorectal cancer patients

The benefit of adding the antiangiogenic drug aflibercept to FOLFIRI regime in metastatic colorectal cancer (CRC) patients resistant to or progressive on an oxaliplatin-based therapy has been previously demonstrated. However, the absence of validated biomarkers to predict greater outcomes is a major challenge encountered when using antiangiogenic therapies. In this study we investigated profiles of circulating microRNAs (miRNAs) to build predictive models of response to treatment and survival. Plasma was obtained from 98 metastatic CRC patients enrolled in a clinical phase II trial before receiving FOLFIRI plus aflibercept treatment, and the circulating levels of 754 individual miRNAs were quantified using real-time PCR. A distinct signature of circulating miRNAs differentiated responder from non-responder patients. Remarkably, most of these miRNAs were found to target genes that are involved in angiogenic processes. Accordingly, some of these miRNAs had predictive value and entered in predictive models of response to therapy, progression of disease, and survival of patients treated with FOLFIRI plus aflibercept. Among these miRNAs, circulating levels of hsa-miR-33b-5p efficiently discriminated between responder and non-responder patients and predicted the risk of disease progression. Moreover, the combination of circulating VEGF-A and miR-33b-5p levels improved clinical stratification of metastatic CRC patients who were to receive FOLFIRI plus aflibercept treatment. In conclusion, our study supports circulating miRNAs as valuable biomarkers for predicting better outcomes in metastatic CRC patients treated with FOLFIRI plus aflibercept.

Lactate activates hypothalamic POMC neurons by intercellular signaling

Previous studies indicate that the activity of hypothalamic POMC neurons can be regulated by glucose via intracellular mechanisms, but its regulation by lactate is poorly understood. In addition to its energetic role, lactate acts as a signaling molecule. In this study, we evaluated the function and location of the lactate receptor, hydroxycarboxylic acid receptor 1 (HCAR1). We used a conditional genetic approach to label POMC neurons and evaluated their sensitivity to lactate using patch-clamp recordings. l-Lactate and 3-chloro-5-hydroxybenzoic acid (3Cl-HBA), HCAR1 specific agonist depolarized POMC neurons and the increase in excitability was abolished by pertussis toxin (PTX), indicating the involvement of Gαi/o-protein-coupled receptors. In addition, the depolarization of a subset of POMC neurons was sensitive to α-cyano-4-hydroxycinnamate (4-CIN), a lactate transporter blocker, suggesting that the depolarization induced by l-lactate can also occur by direct intracellular action. Surprisingly, HCAR1 was not detected in POMC neurons, but instead localized in astrocytes. These results suggest a new lactate-mediated mechanism for astrocyte-neuron intercellular communication.

Effectiveness of copper ions against Mycobacterium avium subsp. paratuberculosis and bacterial communities in naturally contaminated raw cow's milk

AIM

The focus of the present study was to evaluate the copper ions treatment on the viability of Mycobacterium avium subsp. paratuberculosis (MAP) and other bacterial communities in cow's milk.

METHODS AND RESULTS

A copper ions treatment was evaluated in naturally contaminated cow's milk to assay MAP load and/or viability, and relative abundance of other bacterial communities. In addition, physical-chemical analyses of the milk were also performed. All analyses were carried out before and after a copper ions treatment. After copper ions treatment, pH and copper concentration markedly increased in milk; the numbers of viable MAP significantly decreased. The relative abundance of the four target phyla decreased, with the phyla Bacteroidetes and Firmicutes surviving treatment in higher proportions (4 and 2·1% of original populations, respectively). A progressively higher percentage of dead bacterial cells after 5 and 20 min copper ions treatments was found (12 and 35%, respectively).

CONCLUSION

With the exception of some MAP-tolerant strains, we have once again demonstrated that copper ions have a significant inactivating effect on MAP as well as certain other bacterial communities found in naturally contaminated cow's milk.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study showed a significant inactivation of both MAP and other bacteria by copper ions in raw cow's milk, information that could be useful as a tool for MAP control.

Controversies in the treatment of RAS wild-type metastatic colorectal cancer

Objective

To provide guidance for the management of RAS wild-type (wt) metastatic colorectal cancer (mCRC) in daily practice.

Methods

Nominal group and Delphi techniques were used. A steering committee of seven experts analyzed the current management of RAS wt mCRC, through which they identified controversies, critically analyzed the available evidence, and formulated several guiding statements for clinicians. Subsequently, a group of 30 experts (the expert panel) was selected to test agreement with the statements, through two Delphi rounds. The following response categories were established in both rounds: 1 = totally agree, 2 = basically agree, 3 = basically disagree, 4 = totally disagree. Agreement was defined if ≥ 75% of answers were in categories 1 and 2 (consensus with the agreement) or 3 and 4 (consensus with the disagreement).

Results

Overall, 71 statements were proposed, which incorporated the following areas: (1) overarching principles; (2) tumor location; (3) triplets; (4) maintenance; (5) second-line and beyond treatments; (6) Rechallenge and liquid biopsy. After the two Delphi rounds, only six statements maintained a lack of clear consensus.

Conclusions

This document aims to describe the expert’s attitude when dealing with several common clinical questions regarding patients with RAS wt mCRC.

Electronic supplementary material

The online version of this article (10.1007/s12094-020-02475-8) contains supplementary material, which is available to authorized users.

PPARβ/δ-dependent MSC metabolism determines their immunoregulatory properties

Mesenchymal stem cell (MSC)-based therapy is being increasingly considered a powerful opportunity for several disorders based on MSC immunoregulatory properties. Nonetheless, MSC are versatile and plastic cells that require an efficient control of their features and functions for their optimal use in clinic. Recently, we have shown that PPARβ/δ is pivotal for MSC immunoregulatory and therapeutic functions. However, the role of PPARβ/δ on MSC metabolic activity and the relevance of PPARβ/δ metabolic control on MSC immunosuppressive properties have never been addressed. Here, we demonstrate that PPARβ/δ deficiency forces MSC metabolic adaptation increasing their glycolytic activity required for their immunoregulatory functions on Th1 and Th17 cells. Additionally, we show that the inhibition of the mitochondrial production of ATP in MSC expressing PPARβ/δ, promotes their metabolic switch towards aerobic glycolysis to stably enhance their immunosuppressive capacities significantly. Altogether, these data demonstrate that PPARβ/δ governs the immunoregulatory potential of MSC by dictating their metabolic reprogramming and pave the way for enhancing MSC immunoregulatory properties and counteracting their versatility.

0804 Sleep Bruxism, Awake Bruxism and Sleep Related Breathing Disorders in Adults With Down Syndrome

Introduction

To our knowledge, no studies have accessed theawake bruxism (AB) and stage by stage sleep bruxism (SB) in adults with Down syndrome. Recent works have shown that portable PSG systems are accurate for SB assessment even in the absence of audio-video recording. We aimed to evaluate the prevalence of awake bruxism, stage-by-stage sleep bruxism and Sleep Related Breathing Disorders (SRBD) in adults with Down syndrome.

Methods

Twenty-three adults with Down Syndrome (DS) were enrolled in this study. General health, dental status, parafunctional habits and temporomandibular symptoms were assessed. The history of SB/AB was taken from a questionnaire to the caregivers. A portable PSG type II system (Embla Embletta MPR+PG ST+Proxy, Natus, California-USA) was used to perform a full-sleep study at patients’ home. RMMA activity was defined as low (>1 and <2 episodes/h of sleep), moderate (>2 and <4 episodes/h of sleep), or high (>4 episodes/h of sleep). PSG diagnose of SB was assumed if RMMA index was >2 episodes/h of sleep.

Results

According to caregiver’s report, AB was present in all patients whereas only 13.1% had SB. PSG records showed a SB prevalence of 91.3%, with a mean RMMA index 40.0±30.0/h. Only 2 (8,7%) showed RMMA index of 0.0/h. SB episodes were predominant in N3 and REM sleep stage in 14 and 9 patients, respectively. All but one (95,7%) patient (isolated snoring) presented with OSA (AHI=32.8±28.6). A unique TMD symptom (pain on palpation) was present in 8,7% of the global sample.

Conclusion

The high prevalence of “definitive SB” together with the high prevalence of OSA and snoring point in favor to the recommendation of routine PSG in adults with DS. Furthermore, the low sensitivity of parent-oriented questionnaires reinforces the need of more accurate assessment tools in order to get a better standard of care in this particular group of patients.

Support

State of Sao Paulo Research Support Foundation - FAPESP grant number: 2017/06835-8

0657 Impact of Treatment With Mandibular Advancement Oral Appliance on Respiratory Parameters, Sleep and Cardiometabolic Risk Factors of CPAP Non-Adherent Patients With Severe Obstructive Sleep Apnea

Introduction

Obstructive sleep apnea (OSA) may trigger systemic changes linked to important cardiometabolic risk factors such as hypertension, stroke and diabetes II. As a life-threatening, multifactorial disorder, OSA demands a multiprofessional approach. The most common worldwide treatments are Continuous Positive Airway Pressure (CPAP) and Mandibular Advancement Oral Appliance (OAm). The aim of this study was to evaluate the impact of OAm treatment on CPAP non-adherent patients with severe OSA, comparing objective and subjective data between baseline and follow up.

Methods

A prospective study was carried out including non-adherent severe OSA patients, which were referred to OAm therapy evaluation. Patients presenting with snoring, gasping/choking during sleep, fatigue and daily sleepiness were evaluated by a sleep medicine specialist and the diagnosis of severe OSA with a basal polysomnography (PSG). All the patients were treated with a standard OAm (PMPositioner®). Baseline and Follow up (6 months) sleep parameters (PSG and Epworth Sleepiness Scale - ESS) were compared to assess treatment efficacy.

Results

Seventeen patients (9 with hypertension and 8 with hypertension + diabetes) met the inclusion criteria and 13 finished the protocol. After treatment with OAm the following parameters improved significantly: OSA severity (44.5±13.5 to 9.0±4.3, p≤0.001), ODI (46.8±11.6 to 12.1±9.1(p<0.05)), REM (18.4± 4.8 to 21.5± 2.9 (p<0.05)) and SaO2nadir (75.7± 9.4 to 87.0±3.6, p<0.001), ESS (p<0.005). Ten patients (58%) reported a reduction either in systolic and diastolic blood pressure with 3 of them (30%) reduced the hypertensive drug dose.

Conclusion

Our findings show that OAm is a safe and effective treatment option to CPAP non-adherent severe OSA patients. Furthermore OAm therapy had also a positive impact on cardiometabolic risk factors which are particularly relevant outcomes in OSA patients.

Support

State of Sao Paulo Research Support Foundation (FAPESP).

Fate of Mycobacterium avium subsp. paratuberculosis and changes in bacterial diversity populations in dairy slurry after chemical treatments

AIMS

A major drawback of using dairy slurry as fertilizer is that it may contains pathogens such as Mycobacterium avium subsp. paratuberculosis (MAP), and it could represent a risk to animal and public health. Thus, the aim of this study was to evaluate the fate of MAP and bacterial communities in dairy slurry after chemical treatments.

METHODS AND RESULTS

Cattle slurry, naturally contaminated with MAP, was collected from a dairy herd and divided into 32 glass bottles which were assigned to eight different treatments (control, 3·0% CaO, 0·5% NaOH; 0·087%, 0·11% and 0·14% H₂ SO₄ ; and 1·0 and 2·5% KMnO₄ ). Treated dairy slurry samples were evaluated at 0, 1, 3, 7, 15, 30 and 60-days following treatment application for viable MAP and dairy slurry pH, and in addition temperature in this material was monitored continuously. Bacterial counts were estimated at each sampling time. A Bayesian zero-inflated Poisson mixed model was fitted to assess the effect of each treatment on the count of MAP cells. Model results indicated that only the 3·0% CaO treatment had a statistically important negative effect on MAP counts during the study period. For most treatments, MAP was undetectable immediately after chemical treatment but re-appeared over time, in some replicates at low concentrations. However, in those cases MAP counts were not statistically different than the control treatment. Regarding the fate of the other bacterial populations, the Firmicutes phylum was the dominant population in the un-treated slurry while Clostridia class members were among the most prevalent bacteria after the application of most chemical treatments.

CONCLUSION

Only 3% CaO treatment had a statistically important negative effect on MAP viability in cattle slurry.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides evidence of MAP partial control in dairy slurry. This information should be considered as a best management practice to reduce MAP and other pathogens for slurry management on dairy farms.

In vitro inactivation of Mycobacterium avium subsp. paratuberculosis (MAP) by use of copper ions

Background

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of paratuberculosis, a contagious infectious disease that affects domestic and wild ruminants causing chronic inflammation of the intestine. MAP has proven to be very resistant to both physical and chemical processes, making it difficult to control this pathogen. Based on the recognized antimicrobial properties of copper, the objective of this study was to evaluate the effectiveness of copper ions to reduce MAP numbers and/or MAP viability in a fluid matrix. Besides, methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli were used as controls of the effectiveness of copper ions. MAP-spiked PBS was subjected to copper ions treatment at 24 V for 5 min and the PBS suspensions were sampled before and after treatment. MAP viability and quantification were determined using three complementary techniques: a phage amplification assay, MGIT culture and qPCR.

Results

Moderate numbers (10³ CFU ml⁻¹) of the two control bacteria were completely eliminated by treatment with copper ions. For MAP, copper ions treatment reduced both the viability and numbers of this pathogen. Phage assay information quickly showed that copper ions (24 V for 5 min) resulted in a significant reduction in viable MAP. MGIT culture results over time showed statistically significant differences in time-to-detection (TTD) values between PRE and POST treatment. MAP genome equivalent estimates for PBS suspensions indicated that MAP numbers were lower in samples POST-treatment with copper ions than PRE-treatment.

Conclusions

The use of copper ions resulted in a significant reduction of MAP in a liquid matrix, although some MAP survival on some occasions was observed.

Management of unresectable, locally advanced pancreatic adenocarcinoma

The diagnosis of unresectable locally advanced pancreatic adenocarcinoma (LAPC) requires confirmation, through imaging tests, of the unfeasibility of achieving a complete surgical resection, in the absence of metastatic spread. The increase in overall survival (OS), together with an appropriate symptom management is the therapeutic target in LAPC, maintaining an acceptable quality of life and, if possible, increasing the time until the appearance of metastasis. Chemoradiation (CRT) improves OS compared to best support treatment or radiotherapy (RT) but with greater toxicity. No significant increase in OS has been achieved with CRT when compared to chemotherapy (QT) alone in patients without disease progression after four months of treatment with QT. However, a significantly better local control, that is, a significant increase in the time to disease progression was associated with this approach. The greater effectiveness of the schemes FOLFIRINOX and gemcitabine (Gem) + Nab-paclitaxel compared to gemcitabine alone, has been extrapolated from metastatic disease to LAPC, representing a possible alternative for patients with good performance status (ECOG 0-1). In the absence of randomized clinical trials, Gem is the standard treatment in LAPC. If disease control is achieved after 4-6 cycles of QT, the use of CRT for consolidation can be considered an option vs QT treatment maintenance. Capecitabine has a better toxicity profile and effectiveness compared to gemcitabine as a radiosensitizer. After local progression, and without evidence of metastases, treatment with RT or CRT, in selected patients, can support to maintain the regional disease control.

Consensus guidelines for diagnosis, treatment and follow-up of patients with pancreatic cancer in Spain

The management of patients with pancreatic cancer has advanced over the last few years. We convey a multidisciplinary group of experts in an attempt to stablish practical guidelines for the diagnoses, staging and management of these patients. This paper summarizes the main conclusions of the working group. Patients with suspected pancreatic ductal adenocarcinoma should be rapidly evaluated and referred to high-volume centers. Multidisciplinary supervision is critical for proper diagnoses, staging and to frame a treatment plan. Surgical resection together with chemotherapy offers the highest chance for cure in early stage disease. Patients with advanced disease should be classified in treatment groups to guide systemic treatment. New chemotherapeutic regimens have resulted in improved survival. Symptomatic management is critical in this disease. Enrollment in a clinical trial is, in general, recommended.

SEOM Clinical Guideline for the treatment of pancreatic cancer (2016)

Pancreatic cancer remains an aggressive disease with a 5 year survival rate of 5%. Only 15% of patients with pancreatic cancer are eligible for radical surgery. Evidence suggests a benefit on survival with adjuvant chemotherapy (gemcitabine o fluourouracil) after R1/R0 resection. Adjuvant chemoradiotherapy is also a valid option in patients with positive margins. Borderline resectable pancreatic cancer is defined as the involvement of the mesenteric vasculature with a limited extension. These tumors are technically resectable, but with a high risk of positive margins. Neoadjuvant treatment represents the best option for achieving an R0 resection. In advanced disease, two new chemotherapy treatment schemes (Folfirinox or Gemcitabine plus nab-paclitaxel) have showed improvements in overall survival compared with gemcitabine alone. Progress in pancreatic cancer treatment will require a better knowledge of the molecular biology of this disease, focusing on personalized cancer therapies in the near future.

2016 update of the Portuguese recommendations for the use of biological therapies in children and adolescents with Juvenile Idiopathic Arthritis

OBJECTIVE

To provide evidence-based guidance for the rational and safe prescription of biological therapies in children and adolescents with juvenile idiopathic arthritis (JIAs) considering the latest available evidence and the new licensed biologics.

METHODS

Rheumatologists and Pediatricians with expertise in Pediatric Rheumatology updated the recommendations endorsed by the Portuguese Society of Rheumatology and the Portuguese Society of Pediatrics based on published evidence and expert opinion. The level of agreement with final propositions was voted using an online survey.

RESULTS

In total, 20 recommendations to guide the use of biological therapy in children and adolescents with JIAs are issued, comprising 4 general principles and 16 specific recommendations. A consensus was achieved regarding the eligibility and response criteria, maintenance of biological therapy, and procedures in case of non-response, for each JIA category. Specific recommendations concerning safety procedures were also updated.

CONCLUSIONS

These recommendations take into account the specificities of each JIA category and are intended to continuously improve the management of JIA patients.

Clinical guideline SEOM: hepatocellular carcinoma

Hepatocellular carcinoma (HCC) represents the second leading cause of cancer-related death worldwide. Surveillance with abdominal ultrasound every 6 months should be offered to patients with a high risk of developing HCC: Child-Pugh A-B cirrhotic patients, all cirrhotic patients on the waiting list for liver transplantation, high-risk HBV chronic hepatitis patients (higher viral load, viral genotype or Asian or African ancestry) and patients with chronic hepatitis C and bridging fibrosis. Accurate diagnosis, staging and functional hepatic reserve are crucial for the optimal therapeutic approach. Characteristic findings on dynamic CT/MR of arterial hyperenhancement with "washout" in the portal venous or delayed phase are highly specific and sensitive for a diagnosis of HCC in patients with previous cirrhosis, but a confirmed histopathologic diagnosis should be done in patients without previous evidence of chronic hepatic disease. BCLC classification is the most common staging system used in Western countries. Surgical procedures, local therapies and systemic treatments should be discussed and planned for each patient by a multidisciplinary team according to the stage, performance status, liver function and comorbidities. Surgical interventions remain as the only curative procedures but both local and systemic approaches may increase survival and should be offered to patients without contraindications.

Detection of Mycobacterium avium subsp. paratuberculosis in a cattle/pudu interface

ABSTRACTMycobacterium avium subsp. paratuberculosis (Map) is the etiological agent of paratuberculosis. In Chile, information about Map isolation from both domestic ruminant and wildlife species has been accumulating, but it has to be extended to other species. The present study focuses specifically on one wild grazing species, the pudu (Pudu puda), one of the less known South American deer considered an endangered species that shares pastures with cattle in southern Chile, where the greatest part of the country's dairy cattle population is located. Convenient samples from 3 pudus were collected from one dairy farm where Map infection had previously been confirmed in cattle. All three pudus shed the bacterium in feces and the isolates are the same type of Map as described for cattle. This study represents the first case report of Map isolation in the pudu captured from the wild. It is also the first documented association between a Map-infected dairy herd and free-ranging wildlife species, such as pudu in the Los Ríos region, Chile. Since interspecies transmission of Map and other pathogens from livestock to pudu has already been demonstrated, the results from this study suggest that this free-ranging wildlife specie, inhabiting a dairy district in southern Chile, might represent another case of spillover host.

Phase II study of first-line biweekly docetaxel and cisplatin combination chemotherapy in advanced gastric cancer

PURPOSE

Previous studies have shown that docetaxel and cisplatin, as single agents, are effective and relatively well tolerated in patients with advanced gastric cancer. The aim of this study was to assess efficacy and toxicity of a biweekly regimen of docetaxel plus cisplatin in patients with advanced gastric cancer.

PATIENTS/METHODS

Fifty-five patients with histologically proven advanced gastric cancer with at least 1 measurable lesion and ECOG PS ≤ 2 were enrolled. Patients received docetaxel 50 mg/m(2) and cisplatin 50 mg/m(2) every 2 weeks until progression disease, unbearable toxicity or a maximum of 12 cycles.

RESULTS

In total, 426 cycles were administered (median 8.5 cycles) to 52 evaluable patients. One patient (1.9 %) showed a complete response, while 21 (40.4 %) had partial responses. The objective response rate was 42.3 % (95 % CI 28.9-55.7), the median time to progression was 5.5 months (95 % CI 4.0-7.0), and the median overall survival was 8.9 months (95 % CI 6.0-11.9). The most common grade 3-4 toxicities per cycle were haematological [neutropenia (5.9 %)].

CONCLUSIONS

Biweekly administration of docetaxel and cisplatin in advanced gastric cancer has a manageable toxicity profile and shows a promising antitumour activity as a first-line therapy.

Köhler disease: an infrequent or underdiagnosed cause of child's limping?

Köhler disease (KD) is the osteochondrosis of the tarsal navicular bone of the young children, which is a self-limited condition. Typically the child reports pain with mechanical characteristics in the medial region of the foot, however, intermittent or continuous limping may be the only clinical manifestation, which delays the diagnosis and consequently exposes to unnecessary tests and treatments. We describe a bilateral KD whose clinical manifestation was unilateral limping with 4 months evolution. The radiologic evaluation showed flattening, sclerosis and irregular rarefaction of both navicular bones. Claudication persisted for four weeks, after which, the child remains asymptomatic.