What else in times of COVID-19? The role of minimally invasive autopsy for the differential diagnosis of acute respiratory failure in a case of kala-azar.

Visceral leishmaniasis (VL) is a chronic vector-borne zoonotic disease caused by trypanosomatids, considered endemic in 98 countries, mainly associated with poverty. About 50,000-90,000 cases of VL occur annually worldwide, and Brazil has the second largest number of cases in the world. The clinical picture of VL is fever, hepatosplenomegaly, and pancytopenia, progressing to death in 90% of cases due to secondary infections and multi-organ failure, if left untreated. We describe the case of a 25-year-old female who lived in the metropolitan area of Sao Paulo, who had recently taken touristic trips to several rural areas in Southeastern Brazil and was diagnosed post-mortem. During the hospitalization in a hospital reference for the treatment of COVID-19, the patient developed acute respiratory failure, with chest radiographic changes, and died due to refractory shock. The ultrasound-guided minimally invasive autopsy diagnosed VL (macrophages containing amastigote forms of Leishmania in the spleen, liver and bone marrow), as well as pneumonia and bloodstream infection by gram-negative bacilli.

The added value of molecular-based diagnostics in the African forensic medical setting.

Sudden unexpected infant death (SUDI) is reported to be an extraordinarily high burden in sub-Saharan Africa, with the incidence rate in South Africa among the highest in the world. It is common for the cause of many such infant deaths to remain unexplained even after a full medico-legal death investigation, and then to be categorised as a sudden unexplained infant death (SUID). Fortunately, advances in molecular-based diagnostics allow researchers to identify numerous underlying inherited cardiac arrhythmogenic disorders in many SUDI cases, with a predominance of variants identified in the SCN5A gene. Such cardiac arrhythmogenic-related sudden deaths generally present with no structural alterations of the heart that are macroscopically identifiable at autopsy, therefore highlighting the importance of post mortem genetic testing. We report on a significant genetic finding that was made on a SUDI case in which the cause was ascribed to an acute bacterial pneumonia but it was still subjected to post mortem genetic testing of the SCN5A gene. The literature shows that many SUDI cases diagnosed with inherited cardiac arrhythmogenic disorders have demonstrated a viral prodrome within days of their death. It is therefore not uncommon for these cardiac disorders in infants to be mistaken for flu, viral upper respiratory tract infection or pneumonia, and without the incorporation of post mortem genetic testing, any other contributory causes of these deaths are often disregarded. This study highlights the need for research reporting on the genetics of inherited cardiac disorders in Africa.

Autopsy Findings of Severe COVID-19 Pneumonia Combined with Pulmonary Aspergillosis, Pneumothorax, and Pulmonary Thromboembolisms.

BACKGROUND COVID-19-associated pulmonary aspergillosis (CAPA), acute respiratory distress syndrome (ARDS), pulmonary thromboembolism (PTE), and pneumothorax are complications in severe COVID-19 patients. CASE REPORT A 64-year-old Japanese man was diagnosed with COVID-19. His past medical history included uncontrolled diabetes mellitus. He had no vaccination for COVID-19. Despite oxygen inhalation, remdesivir, dexamethasone (6.6 mg per day), and baricitinib (4 mg per day for 12 days), the disease progressed. The patient was supported with mechanical ventilation. Dexamethasone was switched to methylprednisolone (1000 mg per day for 3 days, and then reduced by half every 3 days), and intravenous heparin was initiated. Voriconazole (800 mg on the first day and then 400 mg per day for 14 days) was also started because Aspergillus fumigatus was detected in intratracheal sputum. However, he died of respiratory failure. Pathological findings of autopsy showed: (1) diffuse alveolar damage in a wide area of the lungs, which is consistent with ARDS due to COVID-19 pneumonia, (2) PTEs in peripheral pulmonary arteries, (3) CAPA, and (4) pneumothorax induced by CAPA. These conditions were all active states, suggesting that the treatments were insufficient. CONCLUSIONS Autopsy revealed active findings of ARDS, PTEs, and CAPA in a severe COVID-19 patient despite heavy treatment for each condition. CAPA can be a cause of pneumothorax. It is not easy to improve these conditions simultaneously because their treatments can induce antagonizing biological actions. To prevent severe COVID-19, it is important to reduce risk factors, such as by vaccination and appropriate blood glucose control.

Postmortem examination of equids >1-year-old with enterotyphlocolitis in Ontario: a retrospective descriptive study.

Equine enterotyphlocolitis is an inflammatory process of the intestinal tract of horses that is associated with multiple etiologic agents and risk factors. Most clinical cases do not have an etiologic diagnosis. We describe here the pathogens detected and the histologic lesions found in horses with enterotyphlocolitis in Ontario that were submitted for postmortem examination, 2007-2019. We reviewed the medical records of 208 horses that fulfilled inclusion criteria. Cultures were positive in 67 of 208 (32%) equids for Clostridium perfringens, in 16 of 208 (8%) for Clostridioides difficile, and in 14 of 208 (7%) for Salmonella spp.; 6 of 208 (3%) were positive for Neorickettsia risticii by PCR assay. One horse was positive in a Rhodococcus equi PCR assay. All horses tested by PCR assay for equine coronavirus and Lawsonia intracellularis were negative. The histologic lesions were characterized as follows: 6 of 208 (3%) enteritis, 5 of 208 (2%) typhlitis, 104 of 208 (50%) colitis, 37 of 208 (18%) enterocolitis, 45 of 208 (22%) typhlocolitis, and 11 of 208 (5%) enterotyphlocolitis. We strongly recommend standardized testing of diarrheic horses during and/or after postmortem examination, as well as standardized reporting of histologic lesions in enterotyphlocolitis cases.

Case Report: Molecular autopsy underlie COVID-19-associated sudden, unexplained child mortality.

Herein, we report a child with COVID-19 and seemingly no underlying disease, who died suddenly. The autopsy revealed severe anemia and thrombocytopenia, splenomegaly, hypercytokinemia, and a rare ectopic congenital coronary origin. Immunohistochemical analysis demonstrated that the patient had acute lymphoblastic leukemia of the B-cell precursor phenotype (BCP-ALL). The complex cardiac and hematological abnormalities suggested the presence of an underlying disease; therefore, we performed whole-exome sequencing (WES). WES revealed a leucine-zipper-like transcription regulator 1 (LZTR1) variant, indicating Noonan syndrome (NS). Therefore, we concluded that the patient had underlying NS along with coronary artery malformation and that COVID-19 infection may have triggered the sudden cardiac death due to increased cardiac load caused by high fever and dehydration. In addition, multiple organ failure due to hypercytokinemia probably contributed to the patient's death. This case would be of interest to pathologists and pediatricians because of the limited number of NS patients with LZTR1 variants; the complex combination of an LZTR1 variant, BCP-ALL, and COVID-19; and a rare pattern of the anomalous origin of the coronary artery. Thus, we highlight the significance of molecular autopsy and the application of WES with conventional diagnostic methods.

Lethality of SARS-CoV-2 infection-a comparative autopsy study focusing on COVID-19 development and virus variants.

AIMS: Different SARS-CoV-2 variants are driving various waves of infection of the corona pandemic. Official statistics provide no information on who died due to coronavirus disease 2019 (COVID-19) or an alternative disease during which SARS-CoV-2 infection was detected. The current study aims at addressing the effect of the different variants evolving during the pandemic on fatal outcomes. METHODS AND RESULTS: Standardised autopsies were performed on 117 people who died of a SARS-CoV-2 infection and the findings were interpreted in clinical and pathophysiological contexts. The typical histological sequence of COVID-19-related lung injury was detected independently of the disease-causing virus variant, but was significantly less common (50 versus 80-100%) and less severe in cases infected by omicron variants compared to precedent variants (P < 0.05). COVID-19 was less often the leading cause of death following omicron infection. Extrapulmonary manifestations of COVID-19 did not contribute to death in this cohort. Lethal COVID-19 may occur after complete SARS-CoV-2 vaccination. Reinfection was not the cause of death in any of the autopsies of this cohort. CONCLUSION: Autopsies represent the gold standard in determining the cause of death after SARS-CoV-2 infection and autopsy registers are currently the only available data source allowing for evaluation of which patients died of COVID-19 or with SARS-CoV-2 infection. Compared to previous variants, infection with an omicron variant affected the lungs less frequently and resulted in less severe lung disease.

The need for integrated research autopsies in the era of precision oral medicine.

BACKGROUND: Autopsy has benefited the practice of medicine for centuries; however, its use to advance the practice of oral health care is relatively limited. In the era of precision oral medicine, the research autopsy is poised to play an important role in understanding oral-systemic health, including infectious disease, autoimmunity, craniofacial genetics, and cancer. TYPES OF STUDIES REVIEWED: The authors reviewed relevant articles that used medical and dental research autopsies to summarize the advantages of minimally invasive autopsies of dental, oral, and craniofacial tissues and to outline practices for supporting research autopsies of the oral and craniofacial complex. RESULTS: The authors provide a historical summary of research autopsy in dentistry and provide a perspective on the value of autopsies for high-resolution multiomic studies to benefit precision oral medicine. As the promise of high-resolution multiomics is being realized, there is a need to integrate the oral and craniofacial complex into the practice of autopsy in medicine. Furthermore, the collaboration of autopsy centers with researchers will accelerate the understanding of dental, oral, and craniofacial tissues as part of the whole body. CONCLUSIONS: Autopsies must integrate oral and craniofacial tissues as part of biobanking procedures. As new technologies allow for high-resolution, multimodal phenotyping of human samples, using optimized sampling procedures will allow for unprecedented understanding of common and rare dental, oral, and craniofacial diseases in the future. PRACTICAL IMPLICATIONS: The COVID-19 pandemic highlighted the oral cavity as a site for viral infection and transmission potential; this was only discovered via clinical autopsies. The realization of the integrated autopsy's value in full body health initiatives will benefit patients across the globe.

Morphopathological features induced by SARS-CoV-2 infection - a series of 57 autopsies.

BACKGROUND: COVID-19 is a systemic disease with multiorgan damage, which requires a better understanding and deepening of histopathogenesis in order to improve treatment. Autopsy remains a gold standard to establish certain diagnoses and to integrate the morphological spectrum of lung lesions, explaining the cause of death, into a clinical context. METHODS AND RESULTS: The study included 57 autopsies performed during 2020-2021 associated with SARS-CoV-2 infection. Among the autopsies we performed, diffuse alveolar damage (DAD) was the most common pulmonary morphological change, 31.8% of them with acute or exudative phase and 33.3% with proliferative phase of DAD. Acute fibrous organizing pneumonia or organizing pneumonia with fibrous remodeling processes and pulmonary fibrosis were rarely observed. The most unfavorable outcome and death associated with SARS-CoV-2 infection was frequent in older men, with a high rate of comorbidities. Microscopically, SARS-CoV-2 presents many common aspects with MERS-CoV and SARS-CoV-1, such as alveolar hyaline membrane, desquamated alveolar cells, alveolar edema and alveolar and interstitial lymphocyte and monocytes infiltration. CONCLUSIONS: Our study includes a large number of autopsies on patients with SARS-CoV-2 infection performed in Romania. COVID 19 associated pneumonia combines classical aspects of alveolar and interstitial pneumonia with some peculiarities. Autopsies are of major importance in understanding SARS-CoV-2 infection.

Pulmonary pathology of COVID-19: a review of autopsy studies.

PURPOSE OF REVIEW: COVID-19 lung injury is a common manifestation of severe illness. Lung tissue examination has been largely derived from autopsy - a combination of case reports, small and moderately sized series with international scope. Common and uncommon histopathology provides insight into the progression of severe, fatal disease. RECENT FINDINGS: COVID-19 lung histology is most commonly diffuse alveolar damage as part of acute respiratory distress syndrome. Lung injury can be temporally heterogeneous, with patterns of healing alongside new injury. Viral studies, including immunohistochemistry, RNA in-situ hybridization, and tissue-based Polymerase chain reaction (PCR) assist in discerning complications of therapy (e.g. ventilator-associated pneumonia) from primary viral-induced injury. Response to viral infection produces systemic effects, and one major manifestation is thrombosis of micro-circulation and larger vessels. Less common patterns include neutrophil-rich inflammation, raising speculation that neutrophil extra-cellular traps may play a role in both viral control and exaggerated immune response. SUMMARY: The heterogeneity of fatal cases- persistence of viral infection in lung, clearance of virus but severe lung injury, thrombosis, and exaggerated immune response - suggest that antiviral, antithrombotic, anti-inflammatory, and supportive therapy play a role in treatment, but that the patient-specific cause and timing of the lung injury is important in choosing intervention.

What can autopsy say about COVID-19? A case series of 60 autopsies.

INTRODUCTION: Autopsies in SARS-CoV-2 infected cadavers are mainly performed to distinguish patients who died with SARS-CoV-2 infection from those who died of COVID-19. The aim of the current study is to assess the most frequent autopsy findings in patients who died of COVID-19 and to establish an association with clinical records. MATERIALS AND METHODS: 60 patients died between April 2020 and March 2021 after SARS-CoV-2 infection underwent a full autopsy performed at Fondazione Policlinico Universitario Agostino Gemelli IRCCS (Rome). Ante-mortem diagnosis of SARS-CoV-2 infection was microbiologically confirmed. RESULTS: 55 (92%) of cases had at least a comorbidity. At microscopic examination, 40 (67%) of the patients presented pulmonary intravascular coagulation with an inflammatory pattern. Pulmonary microangiopathy was a rare finding (n = 8; 13%). Myocardiosclerosis was the main heart finding (n = 44; 73%). Liver involvement with congestion and hypotrophy was found in 33 (55%) of cadavers. Renal tubular epithelial exfoliation (n = 12; 20%) and intravascular coagulation (n = 4; 7%) were frequent observations. During hospitalization 31% of patients (n = 19) developed acute kidney injury (AKI). CONCLUSIONS: Lungs and kidneys have been shown to play a pivotal role in COVID-19. The gradual worsening of renal function and AKI might be the result of the progressive collapse of cardiopulmonary system.

Respiratory viruses in medicolegal autopsies during the winter season 2021/2022: observations after reduction of coronavirus disease-19 (COVID-19) pandemic restrictions.

In the context of the coronavirus disease (COVID-19) pandemic, measures were taken to protect the population from infection. These were almost completely lifted in several countries in the spring of 2022. To obtain an overview of the spectrum of respiratory viruses encountered in autoptical routine case work, and their infectivity, all autopsy cases at the Institute of Legal Medicine in Frankfurt/M. with flu-like symptoms (among others) were examined for at least 16 different viruses via multiplex PCR and cell culture. Out of 24 cases, 10 were virus-positive in PCR: specifically, 8 cases with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), 1 with respiratory syncytial virus (RSV), and 1 with SARS-CoV-2 and the human coronavirus OC43 (HCoV-OC43), as a double infection. The RSV infection and one of the SARS-CoV-2 infections were only detected due to the autopsy. Two SARS-CoV-2 cases (postmortem interval of 8 and 10 days, respectively) showed infectious virus in cell culture; the 6 other cases did not show infectious virus. In the RSV case, virus isolation by cell culture was unsuccessful (Ct value of 23.15 for PCR on cryoconserved lung tissue). HCoV-OC43 was measured as non-infectious in cell culture, with a Ct value of 29.57. The detection of RSV and HCoV-OC43 infections may shed light on the relevance of respiratory viruses other than SARS-CoV-2 in postmortem settings; however, further, more extensive studies are needed for a robust assessment of the hazard potential due to infectious postmortem fluids and tissues in medicolegal autopsy settings.

Autopsy of a failed trial part 1: A qualitative investigation of clinician's views on and experiences of the implementation of the DAISIES trial in UK-based intensive eating disorder services.

OBJECTIVE: The DAISIES trial, comparing inpatient and stepped-care day patient treatment for adults with severe anorexia nervosa was prematurely terminated in March 2022 due to poor recruitment. This qualitative study seeks to understand the difficulties faced during the trial by investigating stakeholders' views on and experiences of its implementation. METHOD: Semi-structured interview and focus group transcripts, and trial management and oversight group meeting minutes from May 2020-June 2022 were analysed using thematic analysis. Participants were 47 clinicians and co-investigators involved with the DAISIES trial. The Non-Adoption, Abandonment, Scale-up, Spread, and Sustainability (NASSS) framework was applied to the interpretive themes to classify barriers and facilitators to implementation. RESULTS: Five themes were identified: incompatible participation interests; changing standard practice; concerns around clinical management; systemic capacity and capability issues; and Covid-19 disrupting implementation. Applying the NASSS framework indicated the greatest implementation challenges to arise with the adopters (e.g. patients, clinicians), the organisational systems (e.g. service capacity), and the wider socio-political context (e.g. Covid-19 closing services). CONCLUSIONS: Our findings emphasise the top-down impact of systemic-level research implementation challenges. The impact of the Covid-19 pandemic accentuated pre-existing organisational barriers to trial implementation within intensive eating disorder services, further limiting the capacity for research.

Causes of death of forensic autopsy cases tested positive for COVID-19 in Tokyo Metropolis, Japan.

BACKGROUND: The profile of deaths related to coronavirus disease of 2019 (COVID-19) that occurred outside the hospital in Japan remains unclear because of cautious stance on performing autopsies of COVID-19 positive cases. METHODS: Autopsy cases that tested positive for COVID-19 in the Tokyo Metropolis from April 2020 to July 2022 were handled by medical examiners (n = 41). Age, sex, medical history, autopsy findings, cause of death, postmortem computed tomography (PMCT) findings, and the causal relationship between death and COVID-19 were examined. RESULTS: The mean age of the deceased was 58.0 years (range: 28-96 years), and the study sample consisted of 33 males (80.5%) and 8 females (19.5%). The most frequent medical histories were hypertension (n = 7) and diabetes (n = 7), followed by mental disorders (n = 5). Nineteen cases showed a body mass index ≧25.0 (46.3%). The leading cause of death was pneumonia (n = 17), in which diffuse ground-glass opacification and/or consolidation was noted on PMCT. There were 26 deaths directly related to COVID-19 (63.4%), including pneumonia, myocarditis, laryngotracheobronchitis, and emaciation. The proportion of deaths directly related to COVID-19 was lower after 2022 (42.1%) than prior to 2022 (81.8%). CONCLUSION: Pneumonia was the leading cause of death in this study sample; however, the causes of death in COVID-19 positive cases varied, especially after 2022, when the omicron variant was dominant. Mortality statistics may be affected by viral mutations, and the results of this study further emphasize the need for autopsy because more differential diagnoses should be considered in the phase of the omicron variant.

What Can We Still Learn from Brain Autopsies in COVID-19?

Neuropathological findings have been published from ∼900 patients who died with or from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections, representing less than 0.01% of the close to 6.4 million deaths reported to the World Health Organization 2 years into the coronavirus disease 2019 (COVID-19) pandemic. In this review, we extend our prior work summarizing COVID-19 neuropathology by including information on published autopsies up to June 2022, and neuropathological studies in children, COVID-19 variants, secondary brain infections, ex vivo brain imaging, and autopsies performed in countries outside of the United States or Europe. We also summarize research studies that investigate mechanisms of neuropathogenesis in nonhuman primates and other models. While a pattern of cerebrovascular pathology and microglial-predominant inflammation remains the primary COVID-19-associated neuropathological finding, there is no singular understanding of the mechanisms that underlie neurological symptoms in acute COVID-19 or the post-acute COVID-19 condition. Thus, it is paramount that we incorporate microscopic and molecular findings from brain tissue into what we know about the clinical disease so that we attain best practice guidance and direct research priorities for the study of the neurological morbidity of COVID-19.

Postmortem Histopathologic Findings and SARS-CoV-2 Detection in Autopsy Kidneys of Patients With COVID-19: A Systematic Review and Meta-Analysis.

OBJECTIVES: This systematic review and meta-analysis aimed to investigate the prevalence of postmortem kidney histopathologic features of patients with coronavirus disease 2019 (COVID-19) in addition to the rate of renal tropism in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). METHODS: We searched Web of Science, PubMed, Embase, and Scopus up to September 2022 to identify eligible studies. A random-effects model was used to estimate the pooled prevalence. Cochran Q test and Higgins I2 were used to assess evidence of heterogeneity. RESULTS: In total, 39 studies were included in the systematic review. The meta-analysis included 35 studies consisting of a total of 954 patients, with an average age of 67.1 years. The pooled prevalence of acute tubular injury (ATI)-related changes was the predominant finding (85% [95% confidence interval, 71%-95%]), followed by arteriosclerosis (80%), vascular congestion (66%), and glomerulosclerosis (40%). Endotheliitis (7%), fibrin microthrombi (12%), focal segmental glomerulosclerosis (1%), and calcium crystal deposits (1%) were seen in a smaller number of autopsies. The overall average rate of virus detection was 47.79% in the pooled data of 21 studies (272 samples). CONCLUSIONS: The main finding-ATI-correlated to clinical COVID-19-associated acute kidney injury. The presence of SARS-CoV-2 in kidney samples in addition to vascular lesions in kidneys can be linked to direct kidney invasion by the virus.

Fatal pulmonary thromboembolism in asymptomatic COVID-19.

BACKGROUND: Coronavirus disease 2019 (COVID-19) has claimed the lives of millions of people globally. AIMS: This study aims to identify the pathological findings at autopsy of asymptomatic COVID-19 death, to compare the incidence of acute bilateral pulmonary thromboembolism (ABPTE) in asymptomatic COVID-19 deaths versus non-COVID-19 deaths and to explore the possible pathogenesis of thrombosis in COVID-19. We also consider the place of COVID-19 in the death certification of 4 cases who died from ABPTE. METHODS: This study primarily reviewed post-mortem reports of 6 asymptomatic COVID-19 deaths. Post-mortem reports for the years 2019 and 2020 were also reviewed to establish the incidence of ABPTE. Each post-mortem report was reviewed for gross examination, histology and toxicology findings. A literature review on COVID-19 autopsy findings, COVID-19 pathogenesis, thrombosis in COVID-19 and asymptomatic SARS-CoV-2 infection was also conducted using PubMed. RESULTS: Of the 6 asymptomatic COVID-19 deaths, 4 died as a result of ABPTE, 1 died of ischaemic and hypertensive cardiac disease caused by coronary artery disease and ventricular hypertrophy and the remaining case died of heart failure due to dilated cardiomyopathy caused by subendocardial fibrosis. There were 2 cases of bilateral pulmonary thromboembolism (BPTE) in 2019 out of 140 post-mortems. Excluding the 4 cases of ABPTE described already, there was 1 case of ABPTE in 2020 out of 156 post-mortems. A literature review on the pathogenesis of thrombosis in COVID-19 highlighted the significant role that the endothelium plays. CONCLUSIONS: Massive pulmonary thromboembolism may be a significant cause of death in asymptomatic COVID-19 infection.

Lung Inflammasome Activation in SARS-CoV-2 Post-Mortem Biopsies.

The inflammasome complex is a key part of chronic diseases and acute infections, being responsible for cytokine release and cell death mechanism regulation. The SARS-CoV-2 infection is characterized by a dysregulated cytokine release. In this context, the inflammasome complex analysis within SARS-CoV-2 infection may prove beneficial to understand the disease's mechanisms. Post-mortem minimally invasive autopsies were performed in patients who died from COVID-19 (n = 24), and lung samples were compared to a patient control group (n = 11) and an Influenza A virus H1N1 subtype group from the 2009 pandemics (n = 10). Histological analysis was performed using hematoxylin-eosin staining. Immunohistochemical (IHC) staining was performed using monoclonal antibodies against targets: ACE2, TLR4, NF-κB, NLRP-3 (or NALP), IL-1ß, IL-18, ASC, CASP1, CASP9, GSDMD, NOX4, TNF-α. Data obtained from digital analysis underwent appropriate statistical tests. IHC analysis showed biomarkers that indicate inflammasome activation (ACE2; NF-κB; NOX4; ASC) were significantly increased in the COVID-19 group (p < 0.05 for all) and biomarkers that indicate cell pyroptosis and inflammasome derived cytokines such as IL-18 (p < 0.005) and CASP1 were greatly increased (p < 0.0001) even when compared to the H1N1 group. We propose that the SARS-CoV-2 pathogenesis is connected to the inflammasome complex activation. Further studies are still warranted to elucidate the pathophysiology of the disease.

The Role of NS1 Protein in the Diagnosis of Flavivirus Infections.

Nonstructural protein 1 (NS1) is a glycoprotein among the flavivirus genus. It is found in both membrane-associated and soluble secreted forms, has an essential role in viral replication, and modulates the host immune response. NS1 is secreted from infected cells within hours after viral infection, and thus immunodetection of NS1 can be used for early serum diagnosis of dengue fever infections instead of real-time (RT)-PCR. This method is fast, simple, and affordable, and its availability could provide an easy point-of-care testing solution for developing countries. Early studies show that detecting NS1 in cerebrospinal fluid (CSF) samples is possible and can improve the surveillance of patients with dengue-associated neurological diseases. NS1 can be detected postmortem in tissue specimens. It can also be identified using noninvasive methods in urine, saliva, and dried blood spots, extending the availability and effective detection period. Recently, an enzyme-linked immunosorbent assay (ELISA) assay for detecting antibodies directed against Zika virus NS1 has been developed and used for diagnosing Zika infection. This NS1-based assay was significantly more specific than envelope protein-based assays, suggesting that similar assays might be more specific for other flaviviruses as well. This review summarizes the knowledge on flaviviruses' NS1's potential role in antigen and antibody diagnosis.