Gastrointestinal infection of SARS
Introduction
Introduction to SARS gastrointestinal infections Severe acute respiratory syndrome (SARS), also known as "infectious atypical pneumonia" (infectious atypical pneumonia) is an acute respiratory infection caused by a new coronavirus (SARS-CoV) infection, due to strong contagiousness. It has made rapid progress and has a high mortality rate. It has once constituted a serious threat to human health worldwide. basic knowledge Sickness ratio: 0.002%-0.004% Susceptible people: no special people Mode of infection: respiratory infection Complications: diarrhea
Cause
Causes of gastrointestinal infections in SARS
Infection (30%):
SARS-CoV belongs to the genus Coronavirus of the Coronavirus family. It is an enveloped virus with a diameter of 60-120 nm. The capsule has a petal-like or ciliated protrusion on the envelope. It is about 20 nm long or longer, and the base is narrow and shaped. Crown, similar to the classic coronavirus, the morphogenesis of the virus is long and complex, the mature virus is spherical, elliptical, mature and immature virions vary greatly in size and morphology, and many strange things can appear. The shape, such as kidney shape, drumstick shape, horseshoe shape, bell shape, etc., is easily confused with organelles. In size, the virus particles are reduced from the initial 400nm to the late mature stage of 60-120nm, in the patient's autopsy specimen section. A variety of viral particles can also be seen.
Source of infection (25%):
According to the WHO Multi-Center SARS Collaborative Group, SARS-CoV can survive at least 1 to 2 days in urine and feces at room temperature, and can survive for more than 4 days in the stool of patients with diarrhea (pH higher than normal stool). On the surface of the plastic, it can survive for 24 hours. After the virus in the cell culture supernatant is placed at 4 ° C and 80 ° C for 21 days, the virus titer is only slightly decreased, and the virus in the cell culture supernatant is only decreased after being left at room temperature for 2 days. An order of magnitude, after heating to 56 ° C, the virus titer drops about 10,000 units every 15 minutes, daily disinfectant such as 750ml / L of alcohol for 5min can make the virus lose its vitality, chlorine-containing disinfectant The virus can be inactivated for 5 minutes.
Pathology (30%):
It has been observed that intestinal epithelial cells can be infected by SARS-CoV. Some people think that the main cause of diarrhea in SARS patients is early fever-based viremia and subsequent inflammatory exudation of the lungs. Hypoxemia causes non-specific damage to the gastrointestinal tract. In view of the current immunopathogenesis theory, it is not possible to rule out that the virus causes damage to the gastrointestinal tract through direct or indirect immune mechanisms, and the clear pathogenesis needs further study.
The stomach, intestine, and stomach wall are structurally intact, and the submucosal lymphoid tissues in the stomach, small intestine, and colon are reduced, lymphocytes are sparse, interstitial edema, and in some cases, superficial erosion or ulceration can be seen in the stomach.
Endoscopic colonic mucosa and the end of the ileum were not abnormal. The autopsy specimen also showed normal tissue structure under the microscope, no microvilli atrophy, inflammation, bacterial infection, viral inclusion body or granuloma. In addition, except for partial autolysis changes There is no abnormality in the general eye and light microscope. The virus particles (60-90 nm) observed in the colonic mucosa and the ileum are consistent with SARS-CoV. The virus is confined to the epithelial cells, and the intracellular virus particles may be contained in the expansion. In the cytoplasmic network, the accumulation of viral particles on the surface of the microvilli may indicate that the virus has left the surface of the intestinal cells, and there is still no evidence of villus atrophy.
Prevention
SARS gastrointestinal infection prevention
The focus is on controlling the source of infection and cutting off the route of transmission.
Complication
Gastrointestinal infection complications of SARS Complications, diarrhea
The systemic and respiratory symptoms of SARS patients with diarrhea are not special, and the complications caused by diarrhea may be rare due to the timely treatment of patients.
Symptom
Gastrointestinal infection symptoms of SARS Common symptoms Vomiting after severe exercise, nausea, abdominal pain, diarrhea, loss of appetite
It was reported that 8 of 40 patients with critical SARS had diarrhea and 8 were elderly patients. They had fever at admission and had an initial fever of more than 39 °C. These 8 patients had varying degrees of nausea on the 2nd to 3rd day of onset. , vomiting, loss of appetite, diarrhea, diarrhea within 10 times a day, lasting 3 to 8 days, stools are mostly yellow and watery, without abdominal pain.
Forty-two patients with gastrointestinal symptoms and acute gastrointestinal hemorrhage in 305 SARS cases admitted to Beijing were included in the study. Statistics showed that there were 17 patients with SARS in 17 patients with abdominal pain and 29 patients with diarrhea, accompanied by abdominal pain. There were 7 cases of diarrhea and 4 cases of gastrointestinal bleeding. All patients with abdominal pain or diarrhea had mild symptoms and the duration was generally 1 to 2 days.
In a retrospective analysis in 2004, Cheng et al. of Queen Mary Hospital in Hong Kong reported that 48.6% of SARS patients (69/142) developed diarrhea after initial symptoms (7.6 ± 2.6) days, reaching (8.8 ± 2.4) days. Peak, the number of diarrhea 3 to 24 times / d, an average of 5 times / d, but after statistics, it is considered that diarrhea and mortality are irrelevant.
Leung et al., Prince of Wales Hospital of the Chinese University of Hong Kong, counted 138 SARS patients admitted to the hospital. Watery diarrhea was the most common intestinal symptom. Watery diarrhea occurred in 28 patients in the first week, and 53 patients in the 3-week course. Symptoms of diarrhea, 8 patients with fever with diarrhea and no respiratory symptoms, stool generally does not contain blood and mucus, most abdominal pain is mild, diarrhea is more frequent in the first week of the disease, the average time (3.7 ± 2.7) days, most The symptoms are self-limiting.
Examine
SARS gastrointestinal infection check
1. Stool routine:
Mostly yellow water samples, microscopic examination of a few white blood cells (1 ~ 6 / HP), accompanied by gastrointestinal bleeding more red blood cells, some patients with mild elevation of alanine aminotransferase (ALT), RT-PCR in stool Check out the virus.
2. Blood routine:
In the early to mid-stage of the disease, the white blood cell count is usually normal or decreased, lymphocytes are generally reduced, and platelets are also reduced in some cases. CD3+, CD4+ and CD8+ T cells in the T cell subset are significantly reduced, and the disease can return to normal in the later stage of the disease.
Most patients with SARS imaging have chest X-ray abnormalities in the early stage of onset, mostly patchy or reticular changes. Single lesions often appear in the early stage of the onset, and the lesions increase rapidly in the short term, often involving the lungs or Single lung and multiple leaves, some patients progress rapidly, with large-scale shadows, and the surrounding areas of the lungs are more common, while pleural effusion, cavity formation and hilar lymph node enlargement are less common, and there is no lesion on the chest radiograph. Clinically suspected patients with this disease, chest X-ray examination should be reviewed within 1 to 2 days. Chest CT examination is most common with glass-like changes, lung shadow absorption is absorbed, and dissipation is slow; shadow changes and clinical symptoms and signs may sometimes be inconsistent.
Diagnosis
Diagnosis and diagnosis of gastrointestinal infections of SARS
diagnosis
On the basis of the diagnosis of SARS, patients have different degrees of nausea, vomiting, loss of appetite, diarrhea, diarrhea within 10 times a day for 3 to 8 days, stools are mostly yellow and watery, without abdominal pain, can confirm SARS Gastrointestinal infections.
Differential diagnosis
In addition to the common infectious diarrhea, bacterial dysentery, cholera, Escherichia coli 0157, etc., should also be associated with viral gastroenteritis with respiratory symptoms, should also be alert to the emergence of intestinal double bacteria infection.
