What is it?

In most countries, meningococcus is recognized as a leading cause of meningitis and fulminant septicaemia. It is classified into 12 serogroups based on the structure of the polysaccharide capsule. The majority of invasive meningococcal infections are caused by organisms expressing one of the serogroup A, B, C, X, W135 or Y capsular polysaccharides.

Neisseria species, which usually reside asymptomatically in the human nasopharynx, are easily transmitted to close contacts by respiratory droplets. Nasopharyngeal carriage of potentially pathogenic N. meningitidis has been reported in 4%–35% of healthy adults.1

Clinical features

Symptoms of invasive meningococcal disease (IMD) usually occur 1–4 days after infection. Signs and symptoms of IMD in infants and young children include fever, poor feeding, irritability, lethargy, nausea, vomiting, diarrhoea, photophobia and convulsions. The characteristic feature of meningococcal septicaemia is a hemorrhagic (petechial or purpuric) rash that does not blanch under pressure. Signs of meningitis in older children and adults include neck rigidity, photophobia and altered mental status, whereas in infants non-specific presentation with fever, poor feeding and lethargy is common. Besides meningitis and septicaemia, meningococci occasionally cause arthritis, myocarditis, pericarditis and endophthalmitis.

Most untreated cases of meningococcal meningitis and or septicaemia are fatal. Even with appropriate care up to 10% of patients die, typically within 24–48 hours of the onset of symptoms. Approximately 10% to 20% of survivors of meningococcal meningitis are left with permanent sequelae such as mental retardation, deafness, epilepsy, or other neurological disorders.

Mode of transmission

The disease is mainly transmitted by direct contact through respiratory secretions from infected persons.

Management

Meningococcal infection is a serious illness. Patients should be treated promptly with antibiotics. Close contacts would need to be placed under medical surveillance for early signs of disease and may be given preventive medications.

Prevention

Maintain good personal and environmental hygiene.

WHO recommendations: In countries where the disease occurs less frequently, meningococcal vaccination is recommended for defined risk groups, such as children and young adults residing in closed communities, e.g. boarding schools. Travellers or overseas students to high-endemic areas should be vaccinated against the prevalent serogroup(s). In addition, meningococcal vaccination should be offered to all individuals suffering from immunodeficiency, including asplenia, terminal complement deficiencies, or advanced HIV infection. Meningococcal vaccines against A, C, W, Y serogroup and vaccine against B serogroup  are now registered in Hong Kong.

Hepatitis A is a viral hepatitis caused by the Hepatitis A virus. It is transmitted via intake of contaminated food (e.g. undercooked shellfish) or drinking water. Symptoms include diarrhoea, vomiting, fever and jaundice. Hepatitis A infection does not cause chronic liver disease and is rarely fatal, but it causes debilitating symptoms and fulminant hepatitis, which is associated with high fatality rates.

There is no specific treatment for hepatitis A. Therapy is aimed at maintaining comfort and adequate nutritional and fluid balance. Immunization is effective in preventing Hepatitis A infection and is recommended to residents and travelers to endemic regions (e.g. Mainland China, south-east Asia).

Rotavirus damages the cells on the hair-like projections of the small intestine, reducing their ability of absorption, causing diarrhoea. It is the leading cause of severe, dehydrating diarrhoea in children under the age of 5 years globally. Features of the disease include fever, vomiting and watery diarrhoea. The disease lasts for 3-7 days and young children are at particular risk of dehydration.

Rotavirus is highly contagious. It is transmitted via fecal-oral route, through consumption of contaminated food or water, or by contact with contaminated surface. To date there is no drug available as specific treatment to Rotavirus. Supportive treatment, such as intravenous fluids administration to prevent dehydration and antipyretics, are mainstay of treatment. Disease can be prevented by oral vaccines available to infants.

Vaccines are available in 2-dose or 3-dose from. Infants can be vaccinated from 6 weeks of age. Depend on the brand chosen, the schedule need to be completed by 24 weeks or 32 weeks.

Haemophilus influenzae is a bacterium that causes severe invasive infections such as pneumonia, otitis media, acute epiglottitis and meningitis. It may be present in nasopharynx or healthy adults and transmitted to vulnerable persons via respiratory droplet or contact of contaminated surfaces. 90% of invasive Hib disease affect children under the age of 5 years. Getting vaccinated is an effective way to prevent Hib disease.

Hib vaccine is incorporated into national vaccination scheme in various countries/ regions. To date, it is however not yet included in “Hong Kong Childhood Immunization Programme” by Department of Health. Hib vaccine is included in 5-in-1 or 6-in-1 combined vaccines. It is also available as standalone vaccine. Children can get vaccinated in private clinics.