COVID-19: Abdominal and Pelvic Imaging Findings: A Primer for Radiologists.

ABSTRACT: The COVID-19 pandemic presents an ongoing global health threat. The SARS-CoV-2 is known to cause substantial pulmonary disease, and most of the current radiological publications are dedicated to describing and characterizing these findings. However, studies regarding imaging findings in the abdomen and pelvis of infected patients are still very limited. The aim of this review is to discuss the most frequent abdominal manifestations based on the current literature and representative images from our local experience.

Laparoscopic surgery during the COVID-19 pandemic: detection of SARS-COV-2 in abdominal tissues, fluids, and surgical smoke.

BACKGROUND: There are still concerns over the safety of laparoscopic surgery in coronavirus disease 2019 (COVID-19) patients due to the potential risk of viral transmission through surgical smoke/laparoscopic pneumoperitoneum. METHODS: We performed a systematic review of currently available literature to determine the presence of severe acute respiratory syndrome coronavirus 2 (SARS-COV-2) in abdominal tissues or fluids and in surgical smoke. RESULTS: A total of 19 studies (15 case reports and 4 case series) comprising 29 COVID-19 patients were included. The viral RNA was positively identified in 11 patients (37.9%). The samples that tested positive include the peritoneal fluid, bile, ascitic fluid, peritoneal dialysate, duodenal wall, and appendix. Similar samples, together with the omentum and abdominal subcutaneous fat, tested negative in the other patients. Only one study investigated SARS-COV-2 RNA in surgical smoke generated during laparoscopy, reporting negative findings. CONCLUSIONS: There are conflicting results regarding the presence of SARS-COV-2 in abdominal tissues and fluids. No currently available evidence supports the hypothesis that SARS-COV-2 can be aerosolized and transmitted through surgical smoke. Larger studies are urgently needed to corroborate these findings.

Abdominal Visceral Infarction in 3 Patients with COVID-19.

A high incidence of thrombotic events has been reported in patients with coronavirus disease (COVID-19), which is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. We report 3 clinical cases of patients in Italy with COVID-19 who developed abdominal viscera infarction, demonstrated by computed tomography.

Abdominal Imaging Findings in COVID-19: Preliminary Observations.

Background Angiotensin-converting enzyme 2, a target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), demonstrates its highest surface expression in the lung, small bowel, and vasculature, suggesting abdominal viscera may be susceptible to injury. Purpose To report abdominal imaging findings in patients with coronavirus disease 2019. Materials and Methods In this retrospective cross-sectional study, patients consecutively admitted to a single quaternary care center from March 27 to April 10, 2020, who tested positive for SARS-CoV-2 were included. Abdominal imaging studies performed in these patients were reviewed, and salient findings were recorded. Medical records were reviewed for clinical data. Univariable analysis and logistic regression were performed. Results A total of 412 patients (average age, 57 years; range, 18 to >90 years; 241 men, 171 women) were evaluated. A total of 224 abdominal imaging studies were performed (radiography, n = 137; US, n = 44; CT, n = 42; MRI, n = 1) in 134 patients (33%). Abdominal imaging was associated with age (odds ratio [OR], 1.03 per year of increase; P = .001) and intensive care unit (ICU) admission (OR, 17.3; P < .001). Bowel-wall abnormalities were seen on 31% of CT images (13 of 42) and were associated with ICU admission (OR, 15.5; P = .01). Bowel findings included pneumatosis or portal venous gas, seen on 20% of CT images obtained in patients in the ICU (four of 20). Surgical correlation (n = 4) revealed unusual yellow discoloration of the bowel (n = 3) and bowel infarction (n = 2). Pathologic findings revealed ischemic enteritis with patchy necrosis and fibrin thrombi in arterioles (n = 2). Right upper quadrant US examinations were mostly performed because of liver laboratory findings (87%, 32 of 37), and 54% (20 of 37) revealed a dilated sludge-filled gallbladder, suggestive of bile stasis. Patients with a cholecystostomy tube placed (n = 4) had negative bacterial cultures. Conclusion Bowel abnormalities and gallbladder bile stasis were common findings on abdominal images of patients with coronavirus disease 2019. Patients who underwent laparotomy often had ischemia, possibly due to small-vessel thrombosis. © RSNA, 2020.

Experimental Assessment of Zika Virus Mechanical Transmission by Aedes Aegypti.

The pandemic emergence of several mosquito-borne viruses highlights the need to understand the different ways in which they can be transmitted by vectors to human hosts. In this study, we evaluated the propensity of Aedes aegypti to transmit mechanically Zika virus (ZIKV) using an experimental design. Mosquitoes were allowed to feed on ZIKV-infected blood and were then rapidly transferred to feed on ZIKV-free blood until they finished their meal. The uninfected blood meals, the mosquito abdomens, as well as the mouthparts dissected from fully and partially engorged mosquitoes were analyzed using RT-qPCR and/or virus titration. All the fully engorged mosquito abdomens were ZIKV-infected, whereas their mouthparts were all ZIKV-negative. Nonetheless, one of the partially engorged mosquitoes carried infectious particles on mouthparts. No infectious virus was found in the receiver blood meals, while viral RNA was detected in 9% of the samples (2/22). Thus, mechanical transmission of ZIKV may sporadically occur via Ae. aegypti bite. However, as the number of virions detected on mouthparts (2 particles) is not sufficient to induce infection in a naïve host, our results indicate that mechanical transmission does not impact ZIKV epidemiology.

Neonatal parechovirus infection mimicking a surgical abdomen.

Human parechovirus-3 (PeVA3) infection is a common cause of febrile illness in young infants and the spectrum of clinical presentation is broad. We describe a term infant who presented with marked abdominal distension and anorexia, concerning for an acute surgical abdomen. Evaluation revealed that the infant had PeVA3 infection. This case highlights the importance of recognising severe abdominal distension and discomfort as a clinical presentation associated with PeV and the potential utility of rapid testing for PeV.

Discovery and high prevalence of Phasi Charoen-like virus in field-captured Aedes aegypti in South China.

Arboviruses have caused significant global health concerns during the past decade. In this regard, continuous viral surveillance is essential to timely identify emerging arboviruses and other novel viruses. Here, a novel isolate of Phasi Charoen-like virus (PCLV Zhanjiang01) was identified from field-captured Aedes aegypti mosquitoes in Zhanjiang by next generation sequencing. Phylogenetic analysis suggested that PCLV Zhanjiang01 belonged to the genus Phasivirus in the family Phenuiviridae. The presence of PCLV in three batches of Aedes aegypti confirmed its high prevalence in nature. Further detection of PCLV in progenies and adult males suggested vertical transmission in mosquitoes. In parallel, PCLV was detected from multiple organs indicating its broad tissue distribution in the infected mosquitoes. To the best of our knowledge, this is the first report of PCLV in China. Our results expanded the global biogeographic distribution of PCLV. Further investigations of PCLV on the arboviral transmission and control strategies are warranted.

Deciphering the behaviour manipulation imposed by a virus on its parasitoid host: insights from a dual transcriptomic approach.

Behaviour manipulation imposed by parasites is a fascinating phenomenon but our understanding is still very limited. We studied the interaction between a virus and the parasitic wasp Leptopilina boulardi that attacks Drosophila larvae. Wasps usually refrain to lay eggs into already parasitized hosts (superparasitism avoidance). On the contrary, females infected by the Leptopilina boulardi Filamentous Virus (LbFV) are much more incline to superparasitize. Interestingly, the host-sharing induced by this behaviour modification leads to the horizontal transmission of the virus, thus increasing its fitness at the expense of that of the wasp. To better understand the mechanisms underlying this behaviour manipulation, we studied by RNA sequencing the meta-transcriptome of LbFV and the parasitic wasp both in the abdomen and in the head. We found that the abundance of viral transcripts was independent of the wasp strain but strongly differed between tissues. Based on the tissue pattern of expression, we identified a set of 20 viral genes putatively involved in the manipulation process. In addition, we identified a set of wasp genes deregulated in the presence of the virus either in the abdomen or in the head, including genes with annotations suggesting involvement in behaviour (i.e. Potassium-channel protein). This dataset gives new insights into the behaviour manipulation and on the genetic basis of superparasitism in parasitoids.

Experimental evaluation of infection, dissemination, and transmission rates for two West Nile virus strains in European Aedes japonicus under a fluctuating temperature regime.

West Nile virus (WNV) is continuously spreading in Eastern and Southern Europe. However, the extent of vector competence of Aedes japonicus (Theobald, 1901) is controversial. In this work, we elucidated the dynamics of virus growth in this invasive mosquito species. Females of Ae. japonicus were reared from eggs collected in the field in Switzerland and fed on bovine blood spiked with two WNV lineage 1 strains (FIN, Italy; NY99, USA). Fully engorged females were incubated for 14 days under a fluctuating temperature regime of 24 ± 7 °C (average 24 °C), 45-90% relative humidity, which is realistic for a Central European mid-summer day. Infection, dissemination, and transmission rates were assessed from individual mosquitoes by analyzing the abdomen, legs and wings, and saliva for the presence of viral RNA. Saliva was also investigated for the presence of infectious virus particles. Overall, 302 females were exposed to WNV strain FIN and 293 to strain NY99. A higher infection rate was observed for NY99 (57.4%) compared to FIN (30.4%) (p = 0.003). There was no statistical evidence that the dissemination rate (viral RNA in legs and wings) was different between females infected with FIN (57.1%) compared to NY99 (35.5%) (p = 0.16). Viral RNA load of FIN compared to NY99 was significantly higher in the hemocoel (p = 0.031) of exposed females but not at other sites (legs and wings, saliva). This is the first study describing the vector competence parameters for two WNV strains in a European population of Ae. japonicus. The high dissemination and transmission rates for WNV under a realistic temperature regime in Ae. japonicus together with recent findings on its opportunistic feeding behavior (mammals and birds) indicate its potential role in WNV transmission in Central Europe where it is highly abundant.

A case of abdominal tuberculosis lymphadenitis extending into the gallbladder and duodenum in a human T-cell lymphotropic virus type 1 carrier.

A 69-year-old man with a history of pulmonary tuberculosis presented with fever. He tested positive for the QuantiFERON TB-2G and human T-cell lymphotropic virus type 1 antibodies. Imaging revealed a mass in the neck of the gallbladder, with periportal lymph node enlargement and penetration into the duodenum. A definite diagnosis could not be made, even with a subsequent detailed examination. Finally, cholecystectomy and a lymph node biopsy were performed. Histopathology revealed a caseating granuloma in the lymph nodes and in the serosa of the gallbladder, and polymerase chain reaction was positive for tuberculosis. Therefore, the patient was diagnosed with abdominal tuberculosis lymphadenitis extending into the gallbladder and duodenum.

Development of a duplex real-time RT-qPCR assay to monitor genome replication, gene expression and gene insert stability during in vivo replication of a prototype live attenuated canine distemper virus vector encoding SIV gag.

Advancement of new vaccines based on live viral vectors requires sensitive assays to analyze in vivo replication, gene expression and genetic stability. In this study, attenuated canine distemper virus (CDV) was used as a vaccine delivery vector and duplex 2-step quantitative real-time RT-PCR (RT-qPCR) assays specific for genomic RNA (gRNA) or mRNA have been developed that concurrently quantify coding sequences for the CDV nucleocapsid protein (N) and a foreign vaccine antigen (SIV Gag). These amplicons, which had detection limits of about 10 copies per PCR reaction, were used to show that abdominal cavity lymphoid tissues were a primary site of CDV vector replication in infected ferrets, and importantly, CDV gRNA or mRNA was undetectable in brain tissue. In addition, the gRNA duplex assay was adapted for monitoring foreign gene insert genetic stability during in vivo replication by analyzing the ratio of CDV N and SIV gag genomic RNA copies over the course of vector infection. This measurement was found to be a sensitive probe for assessing the in vivo genetic stability of the foreign gene insert.

The Drosophila Nora virus is an enteric virus, transmitted via feces.

The biology of the Drosophila viruses has not been intensely investigated. Here we have investigated the biology of the Nora virus, a persistent Drosophila virus. We find that injected Nora virus is able to replicate in the files, reaching a high titer that is maintained in the next generation. There is a remarkable variation in the viral loads of individual flies in persistently infected stocks; the titers can differ by three orders of magnitude. The Nora virus is mainly found in the intestine of infected flies, and the histology of these infected intestines show increased vacuolization. The virus is excreted in the feces and is horizontally transmitted. The Nora virus infection has a very mild effect on the longevity of the flies, and no significant effect on the number of eggs laid and the percent of eggs that develop to adults.

RT-PCR analysis of Deformed wing virus in honeybees (Apis mellifera) and mites (Varroa destructor).

Deformed wing virus (DWV) is a honeybee viral pathogen either persisting as an inapparent infection or resulting in wing deformity. The occurrence of deformity is associated with the transmission of DWV through Varroa destructor during pupal stages. Such infections with DWV add to the pathology of V. destructor and play a major role in colony collapse in the course of varroosis. Using a recently developed RT-PCR protocol for the detection of DWV, individual bees and mites originating from hives differing in Varroa infestation levels and the occurrence of crippled bees were analysed. It was found that 100 % of both crippled and asymptomatic bees were positive for DWV. However, a significant difference in the spatial distribution of DWV between asymptomatic and crippled bees could be demonstrated: when analysing head, thorax and abdomen of crippled bees, all body parts were always strongly positive for viral sequences. In contrast, for asymptomatic bees viral sequences could be detected in RNA extracted from the thorax and/or abdomen but never in RNA extracted from the head. DWV replication was demonstrated in almost all DWV-positive body parts of infected bees. Analysing individual mites for the presence of DWV revealed that the percentage of DWV-positive mites differed between mite populations. In addition, it was demonstrated that DWV was able to replicate in some but not all mites. Interestingly, virus replication in mites was correlated with wing deformity. DWV was also detected in the larval food, implicating that in addition to transmission by V. destructor DWV is also transmitted by feeding.

Horizontal transmission of Hz-2V by virus infected Helicoverpa zea moths.

Helicoverpa zea female moths productively infected with Hz-2V have malformed reproductive tissues and are sterile. Virus replication in infected females occurs primarily in the reproductive tissues and culminates with the accumulation of virus-filled vesicles, which form plugs of virus covering the reproductive openings of these insects. The location of this large concentration of virus particles at the terminal abdominal segment of infected females suggests that it may serve as a source of virus that can be transmitted horizontally between moths during mating. In mating experiments it was found that healthy males are attracted to and attempt to mate with infected females, and that these males are able transmit Hz-2V to healthy females during subsequent matings, giving rise to virus infected progeny.

The use of direct sequencing of dengue virus cDNA from individual field-collected Aedes aegypti for surveillance and epidemiological studies.

The relative efficiencies of four methods to extract viral RNA from individual dengue-2 virus (D-2V)-infected mosquitoes, Aedes aegypti (L.) (Diptera: Culicidae), were compared. The most efficient of these methods was then used to extract viral RNA for the preparation of cDNA from the abdomens of six engorged D-2V-infected mosquitoes and sera from three dengue fever (DF) patients collected in an isolated rural town in Colombia. Comparisons of viral envelope (E) gene sequences from each of these strongly suggested that the D-2V population which circulated in this study area was a homogeneous genotype which was unrelated to any of the D-2 viruses isolated from elsewhere in the world. When coupled with our rapid method to identify viruses in individual mosquitoes (Romero-Vivas et al. (1998) Medical and Veterinary Entomology, 12, 101-105), the methodology we describe should be useful for epidemiological and surveillance studies of dengue viruses and other arboviruses.

Simultaneous reactivation of herpes simplex virus and varicella-zoster virus in a patient with idiopathic thrombocytopenic purpura.

Simultaneous reactivation of distinct Herpesviridae with development of clinical manifestations is exceptional. We report a 48-year-old woman suffering from idiopathic thrombocytopenic purpura. As the disease remained refractory to corticosteroids, immunoglobulins and splenectomy, a cure of vinblastine was administered. An atypical stomatitis developed few days later. Immunohistochemistry on a Tzanck smear and a biopsy evidenced a Herpes simplex virus type 1 (HSV-1) infection. The patient presented simultaneously a single necrotic lesion on the abdomen. Immunohistochemistry on a skin biopsy revealed the presence of the varicella-zoster virus (VZV) gE, gB and IE63 proteins. Intravenous aciclovir was initiated. The present case of simultaneous clinical infections by HSV-I and VZV underlines the importance of complementary viral identification testing in the event of unusual clinical presentations.

[Abdominal pain as the initial symptom of visceral varicella zoster infection in hematopoietic stem cell transplant recipients]. / Dolor abdominal como forma de presentación de infección visceral por el virus varicela zoster en receptores de transplante de progenitores hematopoyéticos.

Varicella zoster virus (VZV) infections are an important cause of morbidity after stem cell transplantation (SCT), with no differences in their overall incidence between allogeneic and autologous transplants. We report four patients who developed a disseminated VZV infection with visceral involvement after an allogeneic (n = 3) or autologous (n = 1) SCT. In all 4 cases, the initial symptom was severe abdominal pain which preceded the appearance of the classical herpetic vesicular skin lesions from two to four days in three cases, while one never developed skin lesions. The interval from the transplant to the infection ranged from 5 to 13 months, and all three allogeneic SCT received a T-cell depleted graft, although two suffered from chronic GVHD. All patients had clinical, radiologic and/or biochemical findings indicative of gastrointestinal or visceral involvement. An extensive bibliography review of this specific form of presentation of disseminated VZV infection is presented. The interval from the abdominal pain to the development of the skin lesions has ranged from one to 10 days, and this has led to a delay in the initiation of specific antiviral therapy in many cases, including our only fatal case. We conclude that an abdominal pain of unknown origin in this particular clinical setting should always be regarded as a possible prodromal phase of a disseminated VZV infection.

[Gene expression and distribution in mouse abdominal cavity mediated by adenovirus].

Infection and expression of recombinant human adenovirus in mouse abdominal cavity was reported. After adenovirus vector Ad/RSV-beta-gal harboring the E. coli lacZ marker gene was injected into mice abdominal cavity, the peritoneal surface of jejunum, ileum, colon, uterus, liver, spleen, stomach, bladder, abdominal wall, diaphragm and testis was found large patches of lacZ-positive cells. But the adenovirus vector was not able to penetrate the peritoneum, as demonstrated by histochemical staining. Another adenovirus vector Ad/RSV-tk harboring the HSV-tk gene was injected into mouse abdominal cavity and the mouse was treated with ACV. No acute toxic reaction was observed. Based on these data, the feasibility of gene therapy of malignant tumor within abdominal cavity with adenovirus mediated TK/GCV system was discussed.