- The largest tuberculosis (TB) investigation in Dutch
history begins in Zeist on Mon 31 Jan 2005. 5 percent of the 15 000 people
undergoing tests are expected to have been infected with the bacteria.
- An employee of a C1000 supermarket in the central Dutch
city was diagnosed with a very infectious form of TB in November 2004.
Initial tests confirmed that the 25-year-old man's entire family and 40
of his 79 colleagues have also been infected. Zeist City Council and the
health authority GGD Midden-Nederland decided to examine every customer
who shopped at the supermarket between 18 Nov 2004 and 1 Jan 2005 based
on a telephone survey. The GGD expects to test 15 000 people from the municipality
this week [1st week of February 2005].
- 75 percent of the C1000 customers urged to report for
an examination will undergo Mantoux tests. The procedure involves testing
exposure to TB by injecting diluted tuberculin under the skin. For people
older than 60, lung x- rays will be taken in a mobile health clinic.
- TB doctor and the coordinator of the KNCV Tuberculosis
Fund, Vincent Kuyvenhoven, told newspaper De Volkskrant that it is reasonable
to expect 5 percent of the people examined will be infected with TB. "But
it could also be 10 percent," he said.
- Kuyvenhoven -- who said the investigation was the largest
of its kind in the Netherlands -- explained that the infection rate is
dependent on many factors. This includes how closely the infected supermarket
employee came into contact with customers.
- ProMed Mail
- It is not stated in the above posting whether the index
case had laryngeal tuberculosis or not. It has been generally accepted
that laryngeal TB is the most highly infectious form, but since most cases
are associated with far advanced open cavitary pulmonary disease, the infectivity
of laryngeal TB alone has not been clearly proven. In 2 patients with laryngeal
TB without pulmonary disease, no evidence of intrafamilial spread was found,
suggesting the laryngeal disease in itself may not be so infectious (1).
This moderator has been involved with a similar case in which isolated
laryngeal TB was diagnosed, and despite a delay in making the diagnosis,
no family and hospital spread was found.
- Having a positive Mantoux skin test for TB, assuming
that the test was performed and read appropriately, reflects previous exposure
to TB, not necessarily active infection at that time. Individuals with
a positive skin test (2) have an approximately 10 percent chance of developing
active tuberculosis in their lifetimes, 5 percent in the 1st 2 years and
5 percent afterwards. The risk of reactivation can be as high as 10 percent
per year in AIDS patients.
- It is not clear how an estimate of 5-10 percent skin
test reactivity after this exposure for those shopping in the store is
suggested, as infectivity correlates with degree of exposure. Family and
close friends having a high degree of skin test reactivity (it is likely
the case that none of them have been found to have overt infection) does
not necessarily suggest a high degree of transmission to much more casual
contacts in less confined areas.
- It was Robert Koch in 1891, following his identification
of the human tubercle bacillus, who felt that he could develop a cure for
TB using a filtrate of killed organisms (3). This was not to be the case,
but testing was found to be used as a diagnostic test, first observed by
European veterinarians (4).
- 1. Horowitz G, Kaslow R, Friedland G: Infectiousness
of laryngeal tuberculosis. Am Rev Respir Dis 1976; 114:241-44.
- 2. Lutwick LI: Tuberculin skin testing. In, Tuberculosis,
A Clinical Handbook. Lutwick LI (ed), Chapam & Hall, London, UK, 1995.
- 3. Koch R. Weitere mitteilungen uber ein Heilmittel gegen
Tuberculose. Dtsch Med Wschr 1891; 17:101-102.
- 4. Snider DE: The tuberculin skin test. Am Rev Respir
Dis 1982; 125 (Suppl): 108-18. - Mod.LL
- Patricia A. Doyle, PhD
- Please visit my "Emerging Diseases" message
- Zhan le Devlesa tai sastimasa
- Go with God and in Good Health