Post-mortem findings in a patient with avian influenza A (H5N6) virus infection.

Avian influenza A (H5N6) has been found to infect humans, and has resulted in ten cases with six deaths in China since 2014. Here, we describe the systematic post-mortem pathology of a patient fatally infected with H5N6 virus and evaluate the associated pathogenesis compared with H1N1 pdm09 fatal cases. The most prominent histopathological features were diffuse alveolar damage and pulmonary vasculitis in the lungs of the patient. The virus disseminated to extrapulmonary organs, including the brain. Compared with H1N1 pdm09 fatal infection, H5N6 infection induced a more exacerbated immune response involving overt pulmonary inflammation, which led to alveolar damage and respiratory failure.

Pathology of congenital Zika syndrome in Brazil: a case series

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.

Transmission of methicillin-resistant Staphylococcus aureus infection through solid organ transplantation: confirmation via whole genome sequencing.

We describe two cases of donor-derived methicillin-resistant Staphylococcus aureus (MRSA) bacteremia that developed after transplantation of organs from a common donor who died from acute MRSA endocarditis. Both recipients developed recurrent MRSA infection despite appropriate antibiotic therapy, and required prolonged hospitalization and hospital readmission. Comparison of S. aureus whole genome sequence of DNA extracted from fixed donor tissue and recipients' isolates confirmed donor-derived transmission. Current guidelines emphasize the risk posed by donors with bacteremia from multidrug-resistant organisms. This investigation suggests that, particularly in the setting of donor endocarditis, even a standard course of prophylactic antibiotics may not be sufficient to prevent donor-derived infection.

Vaccine-associated varicella and rubella infections in severe combined immunodeficiency with isolated CD4 lymphocytopenia and mutations in IL7R detected by tandem whole exome sequencing and chromosomal microarray.

In areas without newborn screening for severe combined immunodeficiency (SCID), disease-defining infections may lead to diagnosis, and in some cases, may not be identified prior to the first year of life. We describe a female infant who presented with disseminated vaccine-acquired varicella (VZV) and vaccine-acquired rubella infections at 13 months of age. Immunological evaluations demonstrated neutropenia, isolated CD4 lymphocytopenia, the presence of CD8(+) T cells, poor lymphocyte proliferation, hypergammaglobulinaemia and poor specific antibody production to VZV infection and routine immunizations. A combination of whole exome sequencing and custom-designed chromosomal microarray with exon coverage of primary immunodeficiency genes detected compound heterozygous mutations (one single nucleotide variant and one intragenic copy number variant involving one exon) within the IL7R gene. Mosaicism for wild-type allele (20-30%) was detected in pretransplant blood and buccal DNA and maternal engraftment (5-10%) demonstrated in pretransplant blood DNA. This may be responsible for the patient's unusual immunological phenotype compared to classical interleukin (IL)-7Rα deficiency. Disseminated VZV was controlled with anti-viral and immune-based therapy, and umbilical cord blood stem cell transplantation was successful. Retrospectively performed T cell receptor excision circle (TREC) analyses completed on neonatal Guthrie cards identified absent TREC. This case emphasizes the danger of live viral vaccination in severe combined immunodeficiency (SCID) patients and the importance of newborn screening to identify patients prior to high-risk exposures. It also illustrates the value of aggressive pathogen identification and treatment, the influence newborn screening can have on morbidity and mortality and the significant impact of newer genomic diagnostic tools in identifying the underlying genetic aetiology for SCID patients.

Risk for transmission of Naegleria fowleri from solid organ transplantation.

Primary amebic meningoencephalitis (PAM) caused by the free-living ameba (FLA) Naegleria fowleri is a rare but rapidly fatal disease of the central nervous system (CNS) affecting predominantly young, previously healthy persons. No effective chemotherapeutic prophylaxis or treatment has been identified. Recently, three transplant-associated clusters of encephalitis caused by another FLA, Balamuthia mandrillaris, have occurred, prompting questions regarding the suitability of extra-CNS solid organ transplantation from donors with PAM. During 1995-2012, 21 transplant recipients of solid organs donated by five patients with fatal cases of PAM were reported in the United States. None of the recipients developed PAM, and several recipients tested negative for N. fowleri by serology. However, historical PAM case reports and animal experiments with N. fowleri, combined with new postmortem findings from four patients with PAM, suggest that extra-CNS dissemination of N. fowleri can occur and might pose a risk for disease transmission via transplantation. The risks of transplantation with an organ possibly harboring N. fowleri should be carefully weighed for each individual recipient against the potentially greater risk of delaying transplantation while waiting for another suitable organ. In this article, we present a case series and review existing data to inform such risk assessments.

Neurologic melioidosis in an imported pigtail macaque (Macaca nemestrina).

Burkholderia pseudomallei is the cause of melioidosis in humans and other animals. Disease occurs predominately in Asia and Australia. It is rare in North America, and affected people and animals typically have a history of travel to (in human cases) or importation from (in animal cases) endemic areas. We describe the gross and histopathologic features and the microbiologic, molecular, and immunohistochemical diagnoses of a case of acute meningoencephalomyelitis and focal pneumonia caused by B. pseudomallei infection in a pigtail macaque that was imported from Indonesia to the United States for research purposes. This bacterium has been classified as a Tier 1 overlap select agent and toxin; therefore, recognition of pathologic features, along with accurate and timely confirmatory diagnostic testing, in naturally infected research animals is imperative to protect animals and personnel in the laboratory animal setting.

Bartonella henselae-mediated disease in solid organ transplant recipients: two pediatric cases and a literature review.

Bartonella henselae, the etiologic agent of cat-scratch disease, causes a well-defined, self-limited syndrome of fever and regional lymphadenopathy in immunocompetent hosts. In immunocompromised hosts, however, B. henselae can cause severe disseminated disease and pathologic vasoproliferation known as bacillary angiomatosis (BA) or bacillary peliosis. BA was first recognized in patients infected with human immunodeficiency virus. It has become more frequently recognized in solid organ transplant (SOT) recipients, but reports of pediatric cases remain rare. Our review of the literature revealed only one previously reported case of BA in a pediatric SOT recipient. We herein present 2 pediatric cases, one of which is the first reported case of BA in a pediatric cardiac transplant recipient, to our knowledge. In addition, we review and summarize the literature pertaining to all cases of B. henselae-mediated disease in SOT recipients.

Fatal case of brucellosis misdiagnosed in early stages of Brucella suis infection in a 46-year-old patient with Marfan syndrome.

We report a fatal case of Brucella suis endocarditis initially misdiagnosed by automated identification systems as Ochrobactrum anthropi infection in a patient with a history of Marfan syndrome and recreational feral swine hunting. This report emphasizes the need to consider brucellosis as a part of the differential diagnosis of acute febrile illness, particularly in patients with known risk of exposure.

Improving molecular detection of fungal DNA in formalin-fixed paraffin-embedded tissues: comparison of five tissue DNA extraction methods using panfungal PCR.

DNA extraction from formalin-fixed paraffin-embedded (FFPE) tissues is difficult and requires special protocols in order to extract small amounts of DNA suitable for amplification. Most described methods report an amplification success rate between 60 and 80%; therefore, there is a need to improve molecular detection and identification of fungi in FFPE tissue. Eighty-one archived FFPE tissues with a positive Gomori methenamine silver (GMS) stain were evaluated using five different commercial DNA extraction kits with some modifications. Three different panfungal PCR assays were used to detect fungal DNA, and two housekeeping genes were used to assess the presence of amplifiable DNA and to detect PCR inhibitors. The sensitivities of the five extraction protocols were compared, and the quality of DNA detection (calculated for each kit as the number of housekeeping gene PCR-positive samples divided by the total number of samples) was 60 to 91% among the five protocols. The efficiencies of the three different panfungals used (calculated as the number of panfungal-PCR-positive samples divided by the number of housekeeping gene PCR-positive samples) were 58 to 93%. The panfungal PCR using internal transcribed spacer 3 (ITS3) and ITS4 primers yielded a product in most FFPE tissues. Two of the five DNA extraction kits (from TaKaRa and Qiagen) showed similar and promising results. However, one method (TaKaRa) could extract fungal DNA from 69 of the 74 FFPE tissues from which a housekeeping gene could be amplified and was also cost-effective, with a nonlaborious protocol. Factors such as sensitivity, cost, and labor will help guide the selection of the most appropriate method for the needs of each laboratory.

Histopathologic and immunohistochemical characterization of Nipah virus infection in the guinea pig.

Mortality rate in humans infected with Nipah virus (NiV) has been reported as high as 92%. Humans infected with NiV show a widespread multisystemic vasculitis with most severe clinical and pathologic manifestations in the brain, lungs, and spleen. The purpose of this study was to study pathologic and immunohistochemical findings in guinea pigs infected with NiV. Of 28 animals inoculated intraperitoneally, only 2 survived the infection, and most died between 4 and 8 days postinoculation (dpi). Viral antigen with minimal pathologic changes was first detected 2 dpi in lymph nodes and spleen. More severe changes were noted in these organs 4-8 dpi, where pathologic damage had a vasocentric distribution and viral antigen was abundant in vascular endothelium, tunica media, adventitia, as well as in macrophages lining sinuses. The urinary bladder, uterus, and ovaries were also affected with necrosis and acute inflammation. In these organs, immunohistochemical positive staining was intense in blood vessels, epithelial cells, and ovarian follicles. Approximately 50% of the animals that died or were euthanized in extremis had evidence of viral antigen and histopathologic changes in brain, especially involving meninges and ependymal cells, with lesser changes in the neural parenchyma. A unifying feature of the damage for all affected tissues was necrosis and inflammation of the vasculature, chiefly in arterioles, capillaries, and venules. Inoculation of guinea pigs intraperitoneally with NiV produces a disease with considerable resemblance to the disease in humans, but with reduced pulmonary involvement and marked infection of urinary bladder and the female reproductive tract.

Disseminated infection with Bartonella henselae as a cause of spontaneous splenic rupture.

A 65-year-old man developed massive hemoperitoneum secondary to spontaneous splenic rupture. Histopathological analysis of the spleen demonstrated necrotizing granulomas. Results of serological tests indicated infection with a species of Bartonella, and immunohistochemical staining established Bartonella henselae as the cause of splenitis. To our knowledge, this represents the first reported case of spontaneous splenic rupture caused by infection with a species of Bartonella.

Nipah virus infection, an emerging paramyxoviral zoonosis.

The Nipah virus outbreak represented one of several bat-derived paramyxoviruses that has emerged during the last decade to cause severe human and animal disease. The pathogenesis of Nipah infection is associated with its ability to infect blood vessels and extravascular parenchyma in many organs, particularly in the central nervous system. The clinical manifestations of acute Nipah infection range from fever and mild headache to a severe acute encephalitic syndrome in which there is a high mortality. Much remains to be understood about this new disease, including its intriguing ability to cause relapsing encephalitis in some survivors. This review provides an overview of the Nipah outbreak, focussing on what is presently known about it as an infectious disease, including the clinical aspects, pathology and pathogenesis.

Spotted fever in Brazil: a seroepidemiological study and description of clinical cases in an endemic area in the state of São Paulo.

During 1985-1995, illnesses clinically and epidemiologically compatible with Brazilian spotted fever were identified in 17 patients in the county of Pedreira, in the state of São Paulo, Brazil. Spotted-fever group rickettsial infection was confirmed by serology and/or immunostaining of tissues in 10 of these patients. Immunostaining confirmed infection in a 37-year-old pregnant patient, although rickettsial antigens were not demonstrable in the tissues of the fetus. A serosurvey was conducted in four localities in the county to determine the prevalence of subclinical or asymptomatic infections with spotted fever group rickettsiae. Five hundred and twenty-five blood samples were tested by an indirect immunofluorescence assay for antibodies reactive with Rickettsia rickettsii. Twenty-two (4.2%) of these samples demonstrated titers > or = 1:64. The results indicate that Brazilian spotted fever is endemic within this region of Brazil.

Tissue diagnosis of Ehrlichia chaffeensis in patients with fatal ehrlichiosis by use of immunohistochemistry, in situ hybridization, and polymerase chain reaction.

In the United States, human ehrlichiosis is a complex of emerging tick-borne diseases caused by 3 distinct Ehrlichia species: Ehrlichia chaffeensis, Ehrlichia ewingii, and the human granulocytotropic ehrlichiosis agent. Ehrlichioses are characterized by a mild to severe illness, and approximately 4% of cases are fatal. Because these obligate intracellular bacteria are difficult to resolve with routine histologic techniques, their distribution in tissues has not been well described. To facilitate the visualization and detection of ehrlichiae, immunohistochemistry (IHC), in situ hybridization (ISH), and polymerase chain reaction (PCR) assays were developed by use of tissues from 4 fatal cases of E. chaffeensis infection. Evidence of E. chaffeensis via IHC, ISH, and PCR was documented in all 4 cases. Abundant immunostaining and in situ nucleic acid hybridization were observed in spleen and lymph node from all 4 patients. Significantly, in 2 of these patients, serologic evidence of infection was absent. Use of IHC, ISH, and PCR to visualize and detect Ehrlichia in tissues can facilitate diagnosis of ehrlichial infections.

Fatal encephalitis and myocarditis in young domestic geese (Anser anser domesticus) caused by West Nile virus.

During 1999 and 2000, a disease outbreak of West Nile (WN) virus occurred in humans, horses, and wild and zoological birds in the northeastern USA. In our experiments, WN virus infection of young domestic geese (Anser anser domesticus) caused depression, weight loss, torticollis, opisthotonus, and death with accompanying encephalitis and myocarditis. Based on this experimental study and a field outbreak in Israel, WN virus is a disease threat to young goslings and viremia levels are potentially sufficient to infect mosquitoes and transmit WN virus to other animal species.

Mouse model for Chagas disease: immunohistochemical distribution of different stages of Trypanosoma cruzi in tissues throughout infection.

Different stages of Trypanosoma cruzi are seen during mammalian infection. Histologic sections of infected hearts have shown amastigotes and, when using immunohistochemistry (IHC), parasite antigens; however, demonstration of trypomastigotes in these tissues has proven elusive. Using a mouse strain that develops chagasic cardiomyopathy (histologically similar to human infection) 70 days after injecting T. cruzi-Brazil strain, we studied the distribution of parasite stages and the extent of inflammation. All organs had varying amounts of mononuclear inflammation by day 10, which peaked between day 20 and day 30, and decreased by day 50. Amastigotes were detected in myocytes, histiocytes, acinar pancreatic cells, astrocytes and ependymal cells by day 10, and the number of amastigotes peaked on day 30. Immunohistochemistry demonstrated trypomastigotes in sinusoids, vessels and interstitial tissues of several organs between day 15 and 50. Abundant parasite antigens (granular staining) were detected in connective tissues throughout the infection. The burden of amastigotes and trypomastigotes during the acute phase seems to correlate with the degree of inflammation and granular staining in the chronic stage.

Leptospirosis mimicking acute cholecystitis among athletes participating in a triathlon.

Leptospirosis, a disease acquired by exposure to contaminated water, is characterized by fever accompanied by various symptoms, including abdominal pain. An acute febrile illness occurred in athletes who participated in an Illinois triathlon in which the swimming event took place in a freshwater lake. Of 876 athletes, 120 sought medical care and 22 were hospitalized. Two of the athletes had their gallbladders removed because of abdominal pain and clinical suspicion of acute cholecystitis. We applied an immunohistochemical test for leptospirosis to these gallbladders and demonstrated bacterial antigens staining (granular and filamentous patterns) around blood vessels of the serosa and muscle layer. Rare intact bacteria were seen in 1 case. These results show that leptospirosis can mimic the clinical symptoms of acute cholecystitis. If a cholecystectomy is performed in febrile patients with suspicious environmental or animal exposure, pathologic studies for leptospirosis on formalin-fixed, paraffin-embedded tissues may be of great value.

Exemplar accounts of blending and distinctiveness effects in perceptual old-new recognition.

Recent findings from the perceptual old-new recognition literature indicate that observers have extremely high false-alarm rates to new items that are "blends" of old ones. In addition, evidence suggests that "distinctive" old items--that is, those located in isolated regions of the similarity space--are recognized with higher probability than are typical old items. Both types of phenomena challenge the predictions of global-familiarity exemplar models of perceptual old-new recognition, which posit that the probability that an observer judges an item as old is based on its summed similarity to previously presented exemplars. In the present research the authors pursued these blending and distinctiveness effects by testing paradigms in which similarity relations among objects are highly controlled and in which the variables of blending and distinctiveness are not confounded with other properties associated with the individual objects themselves. In contrast to previous results, the authors found effects of blending and distinctiveness that are compatible with the predictions of a pure summed-similarity exemplar model.

Standardizing Chlamydia pneumoniae assays: recommendations from the Centers for Disease Control and Prevention (USA) and the Laboratory Centre for Disease Control (Canada).

Chlamydia pneumoniae has been associated with atherosclerosis and several other chronic diseases, but reports from different laboratories are highly variable and "gold standards" are lacking, which has led to calls for more standardized approaches to diagnostic testing. Using leading researchers in the field, we reviewed the available approaches to serological testing, culture, DNA amplification, and tissue diagnostics to make specific recommendations. With regard to serological testing, only use of microimmunofluorescence is recommended, standardized definitions for "acute infection" and "past exposure" are proposed, and the use of single immunoglobulin (Ig) G titers for determining acute infection and IgA for determining chronic infection are discouraged. Confirmation of a positive culture result requires propagation of the isolate or confirmation by use of polymerase chain reaction (PCR). Four of 18 PCR assays described in published reports met the proposed validation criteria. More consistent use of control antibodies and tissues and improvement in skill at identifying staining artifacts are necessary to avoid false-positive results of immunohistochemical staining. These standards should be applied in future investigations and periodically modified as indicated.