Microbiology
Pathogens
Norovirus has an incubation period of approximately:
Answer:
The incubation period of norovirus is about 24 - 48 hours.Norovirus
Microbiology / Pathogens / Gastrointestinal Viruses
Last Updated: 21st April 2019
| Virus | Norovirus |
|---|---|
| Epidemiology | Most common cause of viral infectious gastroenteritis in UK, can occur at any age, typically associated with outbreaks in institutions |
| Transmission | Faecal-oral route, direct or indirect contact |
| Incubation period | 24 - 48 hours |
| Clinical features | Nausea, vomiting, watery diarrhoea, symptoms last about 12 - 60 hours |
| Diagnosis | Clinical, confirmed with NAAT of stool sample |
| Treatment | Supportive, fluid replacement |
| Prevention | Isolation, ward closure, good hand-washing technique |
Epidemiology
Norovirus is the most common cause of viral infectious gastroenteritis in the UK. In contrast to rotavirus infection, norovirus infection can occur in people of all ages because immunity to it is not long lasting.
Norovirus is typically associated with outbreaks of acute self-limiting diarrhoea and vomiting (sometimes projectile) in hospitals, care home, schools, nurseries and in other confined communities. Infection is transmitted primarily by the faecal-oral route but it can also be transmitted by contact with an infected person, consumption of contaminated food or water, or contact with contaminated surfaces or objects.
Clinical Features
The incubation period is usually about 24 - 48 hours and the duration of symptoms about 12 - 60 hours. Nausea and vomiting is followed by watery diarrhoea which may be associated with fever, headache and myalgia.
Virus replication occurs in the mucosal epithelium of the small intestine resulting in flattening of the villi and hyperplasia of crypt cells.
Diagnosis
Diagnosis is usually clinical but laboratory diagnosis is important for epidemiological purposes and can be confirmed with NAAT from stool samples.
Treatment and Prevention
Treatment is supportive with fluid replacement. Prevention is by isolation, ward closure, and good hand-washing technique.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
