BCG or Bacillus Calmette Guerin is a vaccine used for prevention of Tuberculosis(TB) in humans since 1921.Approximately 100 million children were administered (vaccinated) with BCG in almost 170 countries in the world.The BCG vaccine is prepared from a strain of attenuated,live tuberculosis bacilli—Mycobacterium Bovis. That has lost it’s virulence in humans by being specially cultered in an artificial medium for years.The bacilli have retained enough strong antigenecity to become an effective Vaccine for the prevention of tuberculosis in human beings.

BCG Vaccine is one of the most widely used vaccines in the world. Its efficacy against TB meningitis in the pediatric age-group is established; but its efficacy against pulmonary TB is appears to be variable. Many countries use BCG for prevention of TB. But a few countries like U.S, they do not use BCG for routine vaccination. This is probably because they believe in detecting the active disease by a reliable Mantoux test, instead of practicing the routine vaccination against a relatively rare condition i.e, the incidence of TB is very low.

History:-

Bovine TB was first recognized in 1854. Robert Koch first distinguished Mycobacterium Bovis from Mycobacterium tuberculosis. Albert Calmette, a French Bacteriologist & his colleague Calmette Guerin a veterinarian were working at pasteur institute in Lille in 1908. They started sub-culturing the virulent strains of tubercle bacillus and noted that sub-culturing the strain in glycerin-bile-potato made it less virulent. Their hypothesis that repeated sub-culturing of a virulent strain of Myco bovis would result in an alternated strain & hence could be used as a vaccine against TB was proved right BCG vaccine was first used in humans 1921.

The bacilli have retained enough, strong antigericity to become a somewhat effective vaccine for prevention of TB in human beings.

Efficacy:-

The most controversial aspect of BCG is its variable efficacy when used in various clinical trials. This appears to depend on the geography. The efficacy of 14% to 84% upto 5 years after immunization. However a clinical trials conducted in South India showed no protective effect.

But BCG vaccine seems to be very effective in preventing miliary TB & TB meningitis. Hence it is still extensively used in countries where efficacy against pulmonacy TB is negligible.

The possible reasons for variable efficacy are many:

1. Genetic variation of the population
2. Genetic variation in BCG strains used
3. Background exposure to the disease-TB.
4. Non-specific immune responses against Mycobacteria by non-tuberculous mycobacteria
5. Immune response with simultaneous infection with parasites, which may blunt the effect of BCG

Adverse effects:-

BCG is one of the widely used vaccines with on unparalleled safety record.

It is recommended that BCG vaccine be given by intra-dermal injection by staff skilled in the technique. BCG immunization causes pain & leaves a scar at the site of injection. The main adverse effects are keloids or large, ugly scars. The insection of deltoid is used for BCG vaccination, because of the least complication when that site is used.

Adverse events to BCG vaccine are mostly localized, and long term complication are rare. If the vaccine is given subcutaneously, it causes a local skin reaction, spreading to the regional lymph adenitis and may cause suppurative lymphadenitits.

95% of subjects vaccinated with BCG develop a local reaction like erythema, induration, muscle soreness, ulceration etc., which is followed by healing & scar formation within 3 months.

Other complication include osteitis (0.01 per million in Japan) & disseminated BCG diseases (0.19 to 1.56 cases per million.

The BCG vaccinated people may not give the potency ratios of the same order as that of naturally infected individuals because of the fact that BCG vaccination leads to a relatively low degree of sensitisation and it may be of a different specificity.

The basic standards of BCG Vaccine:-

• The level of alternation must be such that it avoids severe local lesions or generalized symptoms or progressive tuberculosis.
• The viability of the vaccine must remain high until it is used.
• The vaccine must have the ability to convert the tuberculin reaction within a reasonable time after vaccination.
• The vaccine must have sufficient immunizing potency.
• The cultural & morphologic appearance must be characteristic.
• The vaccine must be free from all other organisms.

BCG Policy:-

WHO Policy:- WHO recommends that BCG be given to all children born in countries highly endemic for Tuberculois because it offers protection against TB meningitis and miliary TB.

INDIA introduced BCG mass immunization in the year 1948, the first Non-European country to do so.

Immunotherapy - BCG 40 mg

Bacillus Calmette-Guérin (BCG) is a live freeze dried preparation from Danish strain 1331. Freeze Dried BCG 40 mg is a therapeutic drug against cancer chemotherapy especially Carcinoma of Urinary Bladder. Intravesical chemotherapy reduces short-term tumor recurrence by about 20%, and long-term recurrence by about 7%, but has not reduced progression or mortality. Presently, BCG immunotherapy remains the most effective treatment and reduces tumor recurrence, disease progression, and mortality.

Bladder cancer is the fourth most common cancer among men and the eighth most common cancer among women. The therapy is used in superficial transitional cell bladder cancer for three reasons – to treat carcinoma in-situ, to reduce the number and frequency of recurrent tumors and to prevent disease progression

Measles

Measles is an infection of the respiratory system caused by a virus, specifically a paramyxovirus of the genus Morbillivirus. Morbilliviruses, like other paramyxoviruses, are enveloped, single-stranded, negative-sense RNA viruses.

Incidence / Prevalence

Worldwide, there are an estimated 30 million cases of measles each year, but the incidence is only 0–10/100 000 people in countries with widespread vaccination programmes such as the USA, UK, Mexico, India, China, Brazil, and Australia. In the USA, before licensing of effective vaccines, more than 90% of people were infected by the age of 15 years. After licensing in 1963, incidence fell by about 98%. The mean annual incidence in Finland was 366/100 000 in 1970, but declined to about zero by the late 1990s. Similarly, the annual incidence declined to about zero in Chile, the English speaking Caribbean, and Cuba during the 1990s, when vaccination programmes were introduced.

Mumps

Mumps or epidemic parotitis is a viral disease of the human species, caused by the mumps virus. Prior to the development of vaccination and the introduction of a vaccine, it was a common childhood disease worldwide, and is still a significant threat to health in the third world.

Incidence / Prevalence

Predominantly affects children, with 32% of reported cases worldwide in children aged 0–4 years and 53% in children aged 5–14 years. In the prevaccine era, by 10 years of age, 87% of the population in England had serological evidence of mumps infection. Since the introduction of the measles, mumps, and rubella (MMR) vaccine, there has been a decrease in the incidence of disease, such that in some countries (e.g. Finland), there is no longer any indigenous disease. Those cases that still occur are usually in an older age group, who are unvaccinated. For example, in 2005, over 56 000 cases of mumps were reported in England and Wales (compared with 16 000 cases in 2004). In contrast to figures from 1989, where 12% of cases occurred in people aged 15 years or over, in 2005 over 80% of cases occurred in this age group.

Rubella

Rubella, commonly known as German measles, is a disease caused by the rubella virus. The name "rubella" is derived from the Latin, meaning little red. Rubella is also known as German measles because the disease was first described by German physicians in the mid-eighteenth century

Incidence / Prevalence

In the prevaccine era in the UK, rubella was uncommon under the age of 5 years, with the peak incidence being at 5–10 years of age. Serological surveys around the world found that by late adolescence/early adulthood, 80% of women had been infected.

Tetanus, also called lockjaw, is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, obligate anaerobic bacterium Clostridium tetani. Infection generally occurs through wound contamination and often involves a cut or deep puncture wound. As the infection progresses, musclespasms develop in the jaw (thus the name "lockjaw") and elsewhere in the body. Infection can be prevented by proper immunization and bypost-exposure prophylaxis.

Rabies virus belongs to the order Mononegavirales, viruses with a nonsegmented, negative-stranded RNA genomes. Within this group, viruses with a distinct "bullet" shape are classified in the Rhabdoviridae family, which includes at least three genera of animal viruses, Lyssavirus, Ephemerovirus, and Vesiculovirus.

Incidence (annual) of Rabies: 18,000 cases (of rabies shots rather than actual rabies)

Incidence Rate: approx 1 in 15,111 or 0.01% or 18,000 people in USA

Incidence extrapolations for USA for Rabies: 18,000 per year, 1,500 per month, 346 per week, 49 per day, 2 per hour

Worldwide incidence of Rabies: 10 million cases (WHO)

Prevalance of Rabies: Although rabies in humans is rare in the United States, as many as 18,000 Americans get rabies shots each year because they have been in contact with animals that may be rabid (rabies-infected).