Vaccines for Special Groups

Vaccines for special groups include meningococcal, typhoid and rabies.

The meningococcal disease is caused by Neisseria meningitidis, or meningococcus which is a gram-negative, biscuit-shaped diplococcus bacteria found only in man. Transmission is from person to person through respiratory droplets. It is not as contagious as the common cold but is transmitted through saliva, and occasionally, prolonged contact with an infected person. The incubation period is from 1 to 10 days. The clinical manifestations include upper respiratory infection with or without bacteremia; bacteremia without sepsis; meningococcemic sepsis without meningitis; meningitis with or without sepsis, meningoencephalitis and focal organ infections. This type of meningitis is the only form of bacterial meningitis known to cause epidemics. It is a serious condition. The more severe disease called meningococcemia is a widespread blood infection with a high rate of mortality. A patient afflicted with this disease can deteriorate within hours. Although a small number of patients die, those who survive incur long term sequelae like deafness and brain damage.

Typhoid or typhoid fever is caused by Salmonella typhi. It is acquired through ingestion of food or water contaminated by fecal material from an infected person. It is characterized by a sustained high fever, profuse sweating, and diarrhea. Occasionally, a rash with flat rose-colored spots may appear. If untreated, typhoid fever can lead to serious complications like intestinal bleeding and perforation, encephalitis, and abscesses and inflammation in other organs including the gallbladder, bones and the heart. Sanitation and good hygiene are critical preventive measures for typhoid.

Rabies is a highly fatal viral encephalomyelitis which is transmitted to man by the bite of a rabid animal. The rabies virus is a bullet-shaped rhabdovirus of the Lyssa group. It can be transmitted in either 2 ways: (1) bite exposure(injection of infectious saliva into abreak in the skin caused by animal's teeth) or (2) non-bite exposure by licking of mucous membranes or scratches, open/healing wounds,abrasions; aerosol; or human to human. The incubation period in man varies from as short as 4 days to as long as 19 years, but is usually between 20-90 days. Ninety five percent of cases develop symptoms within a year from the time of the bite. It tends to be shorter in multiple severe bites or bites on the head and neck areas. The clinical manifestations may range from a prodromal phase characterized by nonspecific constitutional symptoms such as fever, malaise, and body weakness followed by pain or paresthesia at the site of the bite then enters into an acute neurological phase with the characteristic feature of violent and painful spasm of the pharyngeal and laryngeal muscles and eventually death due to a respiratory paralysis.

With the existence of the above disease entities, the use of vaccines for each has been an option in certain areas or conditions.

The meningococcal vaccine is not recommended for routine use. It is recommended only in areas where there is an outbreak as declared by health authorities and for children and adolescents known to be at risk for the disease.

The typhoid vaccine is an active immunization against typhoid fever for adults and children older than 2 years of age. A single dose is recommended for both children and adults. Subjects who remain at risk of typhoid fever should be revaccinated using a single dose of vaccine every 3 - 5 years. This vaccine is also recommended for travelers to areas with a risk of exposure to salmonella typhi or persons infected with Salmonella typhi. There are two vaccines for typhoid - an oral live attenuated and an injectible.

Based on the Anti-rabies Act 2007, pre-exposure prophylaxis for children aged 5 years and above is recommended where there is a high incidence of rabies (>2.5 human rabies/million population). The regions with a high incidence of rabies reported in 2006 are Regions 1,2,3,5,7,8,12 and CAR. Booster is not mandatory but may be given every 3 years depending on continuing risk of exposure. Any exposure regardless of severity after completion of the Primary series should be given rabies vaccines as follows: interval from last dose of 0-6 months needs one booster dose, >6 months - 3 years, needs 2 booster doses(given on days 0, 3) and > 3 years require a full dose of vaccine (days 0,3,7,14,28) without Rabies immunoglobulin.