Roosecelis Brasil Martines

Tissue and cellular tropism, pathology and pathogenesis of Ebola and Marburg viruses

Ebola viruses and Marburg viruses include some of the most virulent and fatal pathogens known to humans. These viruses cause severe haemorrhagic fevers, with case fatality rates in the range 25–90%. The diagnosis of filovirus using formalin‐fixed tissues from fatal cases poses a significant challenge. The most characteristic histopathological findings are seen in the liver; however, the findings overlap with many other viral and non‐viral haemorrhagic diseases. The need to distinguish filovirus infections from other haemorrhagic fevers, particularly in areas with multiple endemic viral haemorrhagic agents, is of paramount importance. In this review we discuss the current state of knowledge of filovirus infections and their pathogenesis, including histopathological findings, epidemiology, modes of transmission and filovirus entry and spread within host organisms. The pathogenesis of filovirus infections is complex and involves activation of the mononuclear phagocytic system, with release of pro‐inflammatory cytokines, chemokines and growth factors, endothelial dysfunction, alterations of the innate and adaptive immune systems, direct organ and endothelial damage from unrestricted viral replication late in infection, and coagulopathy. Although our understanding of the pathogenesis of filovirus infections has rapidly increased in the past few years, many questions remain unanswered. Copyright

Pathology of congenital Zika syndrome in Brazil: a case series

BACKGROUND Zika virus is an arthropod-borne virus that is a member of the family Flaviviridae transmitted mainly by mosquitoes of the genus Aedes. Although usually asymptomatic, infection can result in a mild and self-limiting illness characterised by fever, rash, arthralgia, and conjunctivitis. An increase in the number of children born with microcephaly was noted in 2015 in regions of Brazil with high transmission of Zika virus. More recently, evidence has been accumulating supporting a link between Zika virus and microcephaly. Here, we describe findings from three fatal cases and two spontaneous abortions associated with Zika virus infection. METHODS In this case series, formalin-fixed paraffin-embedded tissue samples from five cases, including two newborn babies with microcephaly and severe arthrogryposis who died shortly after birth, one 2-month-old baby, and two placentas from spontaneous abortions, from Brazil were submitted to the Infectious Diseases Pathology Branch at the US Centers for Disease Control and Prevention (Atlanta, GA, USA) between December, 2015, and March, 2016. Specimens were assessed by histopathological examination, immunohistochemical assays using a mouse anti-Zika virus antibody, and RT-PCR assays targeting the NS5 and envelope genes. Amplicons of RT-PCR positive cases were sequenced for characterisation of strains. FINDINGS Viral antigens were localised to glial cells and neurons and associated with microcalcifications in all three fatal cases with microcephaly. Antigens were also seen in chorionic villi of one of the first trimester placentas. Tissues from all five cases were positive for Zika virus RNA by RT-PCR, and sequence analyses showed highest identities with Zika virus strains isolated from Brazil during 2015. INTERPRETATION These findings provide strong evidence of a link between Zika virus infection and different congenital central nervous system malformations, including microcephaly as well as arthrogryposis and spontaneous abortions. FUNDING None.

Zika Virus RNA Replication and Persistence in Brain and Placental Tissue.

Zika virus is causally linked with congenital microcephaly and may be associated with pregnancy loss. However, the mechanisms of Zika virus intrauterine transmission and replication and its tropism and persistence in tissues are poorly understood. We tested tissues from 52 case-patients: 8 infants with microcephaly who died and 44 women suspected of being infected with Zika virus during pregnancy. By reverse transcription PCR, tissues from 32 (62%) case-patients (brains from 8 infants with microcephaly and placental/fetal tissues from 24 women) were positive for Zika virus. In situ hybridization localized replicative Zika virus RNA in brains of 7 infants and in placentas of 9 women who had pregnancy losses during the first or second trimester. These findings demonstrate that Zika virus replicates and persists in fetal brains and placentas, providing direct evidence of its association with microcephaly. Tissue-based reverse transcription PCR extends the time frame of Zika virus detection in congenital and pregnancy-associated infections.

Zika Virus: Pathology From the Pandemic.

CONTEXT -As the number of Zika virus (ZIKV) infections continues to grow, so, too, does the spectrum of recognized clinical disease, in both adult and congenital infections. Defining the tissue pathology associated with the various disease manifestations provides insight into pathogenesis and diagnosis, and potentially future prevention and treatment, of ZIKV infections. OBJECTIVE -To summarize the syndromes and pathology associated with ZIKV infection, the implications of pathologic findings in the pathogenesis of ZIKV disease, and the use of pathology specimens for diagnosis of ZIKV infection. DATA SOURCES -The major sources of information for this review were published articles obtained from PubMed and pathologic findings from cases submitted to the Infectious Diseases Pathology Branch at the Centers for Disease Control and Prevention. CONCLUSIONS -Pathologic findings associated with ZIKV infection are characteristic but not specific. In congenital Zika syndrome, tissue pathology is due to direct viral infection of neural structures, whereas in Guillain-Barré syndrome, pathology is likely due to a postviral, aberrant host-directed immune response. Both fetal and placental pathology specimens are useful for ZIKV diagnosis by molecular and immunohistochemical assays; however, the implications of ZIKV detection in placentas from second- and third-trimester normal live births are unclear, as the potential postnatal effects of late gestational exposure remain to be seen.

Phylogeography of Rickettsia rickettsii Genotypes Associated with Fatal Rocky Mountain Spotted Fever

Rocky Mountain spotted fever (RMSF), a tick-borne zoonosis caused by Rickettsia rickettsii, is among the deadliest of all infectious diseases. To identify the distribution of various genotypes of R. rickettsii associated with fatal RMSF, we applied molecular typing methods to samples of DNA extracted from formalin-fixed, paraffin-embedded tissue specimens obtained at autopsy from 103 case-patients from seven countries who died of RMSF. Complete sequences of one or more intergenic regions were amplified from tissues of 30 (29%) case-patients and revealed a distribution of genotypes consisting of four distinct clades, including the Hlp clade, regarded previously as a non-pathogenic strain of R. rickettsii. Distinct phylogeographic patterns were identified when composite case-patient and reference strain data were mapped to the state and country of origin. The phylogeography of R. rickettsii is likely determined by ecological and environmental factors that exist independently of the distribution of a particular tick vector.

Immunolocalization and Distribution of Rubella Antigen in Fatal Congenital Rubella Syndrome.

Background An estimated 100,000 cases of congenital rubella syndrome (CRS) occur worldwide each year. The reported mortality rate for infants with CRS is up to 33%. The cellular mechanisms responsible for the multiple congenital defects in CRS are presently unknown. Here we identify cell types positive for rubella virus (RV) in CRS infants. Methods Cells and organs involved in RV replication were identified in paraffin-embedded autopsy tissues from three fatal case-patients by histopathologic examination and immunohistochemical (IHC) staining using a rabbit polyclonal RV antibody. Normal rabbit antisera and RV antisera preabsorbed with highly purified RV served as negative controls. Results RV antigen was found in interstitial fibroblasts in the heart, adventitial fibroblasts of large blood vessels, alveolar macrophages, progenitor cells of the outer granular layer of the brain, and in capillary endothelium and basal plate in the placenta. The antibody specificity was verified by IHC staining of multiple tissue sections from other infectious disease cases. RV infection of each cell type is consistent with abnormalities which have been identified in patients with CRS, in the heart, large blood vessels, and brain. Antigen distribution was consistent with inflammatory response to vascular injury and systemic spread of RV. Conclusions The identification of RV positive cell types in CRS is important to better understand the pathology and pathogenesis of CRS.

Postmortem Findings in Patient with Guillain-Barré Syndrome and Zika Virus Infection

Postmortem examination results of a patient with Guillain-Barré syndrome and confirmed Zika virus infection revealed demyelination of the sciatic and cranial IV nerves, providing evidence of the acute demyelinating inflammatory polyneuropathy Guillain-Barré syndrome variant. Lack of evidence of Zika virus in nervous tissue suggests that pathophysiology was antibody mediated without neurotropism.

Acanthamoeba endophthalmitis during treatment for cutaneous disease in a renal transplant patient

Acanthamoeba infections are difficult to diagnose and treat. We present a renal transplant patient who developed Acanthamoeba endophthalmitis on therapy with posaconazole and miltefosine for cutaneous acanthamobiasis. The patient was maintained on intracameral voriconazole injections, and oral azithromycin, fluconazole, and flucytosine. This case highlights novel presentations and treatments for acanthamoebic infection.

Improved Detection and Accuracy of Mycobacterium Species Identification from Paraffin Embedded Tissues of Patients by Using Multigene Targeted PCR and Sequencing

Abstract Background Prompt and accurate identification and differentiation of Mycobacterium tuberculosis-complex (MTBC) from non-tuberculous mycobacteria (NTM) is crucial for the selection of antimicrobial treatment and appropriate public health response. Diagnosis and characterization of mycobacteria is challenging due to diverse clinical presentations, lack of sensitivity of smear microscopy, and fastidious culture identification. Moreover, because of clinical suspicion of noninfectious conditions, specimens are often not processed for culture and formalin-fixed, paraffin-embedded (FFPE) tissues are the only specimens available. For rapid and accurate identification of Mycobacterium spp. from patient tissues, sensitive and specific molecular assays combined with other tissue-based methods are vital. Methods We extracted DNA from FFPE tissues from 931 patients with clinical and histopathological suspicion of mycobacterial infection (received during 2013–2016) and evaluated by multistage, multigene targeted Mycobacterium-genus, complexes-and species-specific PCR assays (targets including 16S rRNA, rpoB, groEL, IS6110, RLEP) and sequencing. Tissues were also examined by acid-fast bacilli (AFB) stains and mycobacteria immunohistochemistry (IHC). Assays to detect mutations associated with drug resistance were performed on MTBC cases. Results A Mycobacterium species was detected in 465 (50%) cases by PCR and sequencing. Of these, 380 (82%) were positive by Mycobacterium PCR targeting 16S rRNA. 85 cases (18%), including 9 MTBC, 12 M. avium complex and 3 M. leprae, were positive by other PCRs. Co-infection of MTBC and NTM spp. was detected in 5 cases. Of 465 PCR positive cases, 327 (70%) showed immunostaining and 223 (48%) were AFB-positive. Molecular markers for drug resistance were detected in 9 out of 88 (10%) tested MTBC cases. Conclusion FFPE tissue analysis by multigene targeted PCR assays expands the opportunities for rapid identification of Mycobacterium species, allows differentiation of MTBC from NTM, and helps to detect co-infections. Using multigene targeted PCRs in combination with histopathology and IHC improve the accuracy of diagnosis, particularly in the presence of commensal and environmental pathogens. Disclosures All authors: No reported disclosures.

Zika Virus, a Newly Emergent Flavivirus

Zika virus (ZIKV) is a single-stranded, positive-sense RNA virus in the family Flaviviridae that was first isolated in 1947 from a rhesus macaque in the Zika forest in Uganda. A large outbreak of ZIKV infection in humans was confirmed in April 2015 in Brazil. Infection early in pregnancy has been associated with congenital microcephaly and other adverse outcomes, including pregnancy loss [1]. ZIKV is the first infectious agent that has been found to cause congenital defects in more than 50 years, and the first mosquito-borne illness that is associated with congenital defects. Understanding the disease biology of ZIKV is crucial for effective intervention. To this end, correlating clinical manifestations with underlying tissue pathology can provide critical insights into disease pathogenesis. The symptoms of ZIKV infection in adults are generally mild, and include fever, rash, joint pain, conjunctivitis (red eyes), muscle pain, and headache, but approximately 80 percent of ZIKV patients are asymptomatic. ZIKV illness may lead to cases of Guillain-Barré syndrome, an illness where the immune system attacks peripheral nerves, which can result in (mostly) temporary partial or total paralysis. ZIKV can be transmitted by mosquitoes, sex and blood transfusions. Other illnesses with similar clinical symptoms which are circulating in the same regions include Chikungunya and dengue.