Does Crimean-Congo Hemorrhagic Fever Cause a Vasculitic Reaction with Pulmonary Artery Enlargement and Acute Pulmonary Hypertension?

Pulmonary vascular enlargement on thoracic CT for diagnosis and differential diagnosis of COVID-19: a systematic review and meta-analysis

Background

The 2019 coronavirus disease (COVID-19) has become a global pandemic. To date, although many studies have reported on the computed tomography (CT) manifestations of COVID-19, the vascular enlargement sign (VES) of COVID-19 has not been deeply examined, with the few available studies reporting an inconsistent prevalence. We thus performed a systematic review and meta-analysis based on the best available studies to estimate the prevalence and identify the underlying differential diagnostic value of VES.

Methods

We searched nine English and Chinese language databases up to April 23, 2020. Studies that evaluated CT features of COVID-19 patients and reported VES, with or without comparison with other pneumonia were included. The methodologic quality was assessed using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2). Meta-analyses with random effects models were performed to calculate the aggregate prevalence and pooled odds ratios (ORs) of VES. We also conducted meta-regression and subgroup analyses to analyze heterogeneity.

Results

VES findings from a total of 1969 patients were summarized and pooled across 22 studies. Our analysis demonstrated that the prevalence of VES among COVID-19 patients was 69.37% [95% confidence interval (CI): 57.40-79.20%]. Compared with non-COVID-19 patients, VES manifestation was more frequently observed in confirmed COVID-19 patients (OR =6.43, 95% CI: 3.39-12.22). Studies that explicitly defined distribution of VES in the lesion area demonstrated a significantly higher prevalence (P=0.03). Subgroup analyses also revealed a relatively higher VES rate in studies with a sample size larger than 50, but the difference was not statistically significant. No significant difference in VES rates was found between different countries (China/Italy), regions (Hubei/outside Hubei), average age groups (over/less than 50-year-old), or slice thicknesses of CT scan. Extensive heterogeneity was identified across most estimates (I²>80%). Some of the variations (R²=19.73%) could be explained by VES distribution, and sample size. No significant publication bias was seen (P=0.29).

Conclusions

VES on thoracic CT was found in almost two-thirds of COVID-19 patients, and was more prevalent compared with that of the non-COVID-19 patients, supporting a promising role for VES in identifying pneumonia caused by coronavirus.

Crimean-Congo hemorrhagic fever: An update

Crimean-Congo hemorrhagic fever (CCHF) is a severe form of hemorrhagic fever caused by a virus of the genus Nairovirus. The amplifying hosts are various mammal species that remain asymptomatic. Humans are infected by tick bites or contact with animal blood. CCHF has a broad geographic distribution and is endemic in Africa, Asia (in particular the Middle East) and South East Europe. This area has expanded in recent years with two indigenous cases reported in Spain in 2016 and 2018. The incubation period is short with the onset of symptoms in generally less than a week. The initial symptoms are common to other infectious syndromes with fever, headache, myalgia and gastrointestinal symptoms. The hemorrhagic syndrome occurs during a second phase with sometimes major bleeding in and from the mucous membranes and the skin. Strict barrier precautionary measures are required to prevent secondary and nosocomial spread. CCHF may be documented by PCR detection of the virus genome during the first days after the onset of illness, and then by serological testing for IgM antibodies as from the 2nd week after infection. Patient management is mainly based on supportive care. Despite a few encouraging retrospective reports, there is no confirmed evidence that supports the use of ribavirin for curative treatment. Nevertheless, the World Health Organization continues to recommend the use of ribavirin to treat CCHF, considering the limited medical risk related to short-term treatment. The prescription of ribavirin should however be encouraged post-exposure for medical professionals, to prevent secondary infection.

Animal Models for Crimean-Congo Hemorrhagic Fever Human Disease

Crimean-Congo hemorrhagic fever virus (CCHFV) is an important tick-borne human pathogen endemic throughout Asia, Africa and Europe. CCHFV is also an emerging virus, with recent outbreaks in Western Europe. CCHFV can infect a large number of wild and domesticated mammalian species and some avian species, however the virus does not cause severe disease in these animals, but can produce viremia. In humans, CCHFV infection can lead to a severe, life-threating disease characterized by hemodynamic instability, hepatic injury and neurological disorders, with a worldwide lethality rate of ~20-30%. The pathogenic mechanisms of CCHF are poorly understood, largely due to the dearth of animal models. However, several important animal models have been recently described, including novel murine models and a non-human primate model. In this review, we examine the current knowledge of CCHF-mediated pathogenesis and describe how animal models are helping elucidate the molecular and cellular determinants of disease. This information should serve as a reference for those interested in CCHFV animal models and their utility for evaluation of medical countermeasures (MCMs) and in the study of pathogenesis.