Tuberculosis in the South Eastern Health Board area of Ireland 1997-2002

Authors: P. Prendiville, A. Veale, M. O’Connor, O. O’Reilly,

Public Health Department, South Eastern Health Board, Lacken, Kilkenny, Ireland.

Background: The purpose of this review was to provide updated information on the local clinical presentations of Tuberculosis (TB) in the South Eastern health Board (SEHB) for health care staff in the region, and so increase awareness of the disease and the issues surrounding the management of TB. The SEHB is divided into four Community Care Areas –Carlow/Kilkenny, South Tipperary, Waterford and Wexford, and has a total population of 391,517 (1996 census)

Methods:

  • Enhanced surveillance data on all cases of TB in the SEHB from 1997-2002.
  • Data included the socio-demographic, clinical and outcome data
  • One cluster was identified using DNA testing of isolates
  • Other clusters were of family or close contacts.
  • Data was analysised using EPI6 programme

Results:

  1. Socio-demographic: The total number of TB cases during the six-year period was 224. The crude annual incident rate varied from 5.4-12.5/100,000 populations (graph 1).
  • TB occurred in all age groups (graph 2)
  • 7 (3%) cases were aged under 15 years
  • 72 (32%) cases were aged over 64 years
  • Male: female ratio was 1.7:1,
  • 28 (12.5%) cases were born outside Ireland
  • Most frequently cited occupational groups are shown in graph 3.

Graph 1. Incident rates/100,000 populations in each area of SEHB. The total population of the SEHB is 391,517 (1996 census). The increase in Waterford in 2002 is accounted for by a cluster.

Graph 2. Age groups. The 7 cases in the under 15 age-group were all contacts of an infectious index case within the family, 6 had primary TB and 1 had milary TB. The case of milary TB had not had BCG vaccine.

Graph 3. Occupational group was recorded in 109 cases. Most frequently cited occupational groups were farming (18), catering/bar work (15), factory employee (14), construction worker (13) and health care worker (13). In 96 cases employment status was recorded – 48 were employed, 29 retired, 15 unemployed and 4 house duties.

2. Clinical data:

  • 32 (14%) cases had a past history of TB
  • 50 cases recorded a history of contact with TB
  • in 33 of these the contact was with an extended family member
  • 49 (22%) cases accounted for 15 known clusters
  • 17 (7.5%) cases found by contact tracing
  • 5 cases were HIV positive
  • 166 Pulmonary cases ( including Pulmonary/extra pulmonary)
  • 51 extra pulmonary cases (19 different sites)
  • 7 primary TB
  • 152 (68%) were laboratory confirmed
  • 61 (27%) of total were sputum smear positive
  • 131(58%) culture positive (123 MTB, 6 M. bovis)
  • 8 isolates were drug resistant (see table 1)
  • 1 case of multidrug resistant (MDR) M. tuberculosis .

Graph 4. Total TB cases by site and including data on positive TB cultures.

Sites are categorized as Pulmonary, extra pulmonary, pulmonary and extra pulmonary (in the one patient) and primary. Extra pulmonary sites included glands (25 cases), pleura (15 cases), 3 cases each in bone, abscess and liver, 2 cases each of meningeal and renal, and one case each of TB peritoneal, endometrium, epidydimus, milary, epidermal and uveitis.

Graph 5: TB isolates by culture site. In total there were 131culture positive isolates - 123 Mycobacterium tuberculosis (MTB), 6 M bovis, 1 Mycobacterium species and 1 identification not available

Resistant TB isolates.

isolate / resistance / Site / Age / Sex / Year / Comment
1 /

M.bovis

/ INAH / Sputum / 17 / M / 1997 / Smear positive
2 /

M.bovis

/ INAH / Sputum / 73 / F / 1998 / Treated in the past
3 / MTB / INAH / Sputum / 50 / F / 1999 / Smear positive
4 / MTB / INAH / Sputum / 47 / F / 1999 / Smear negative
5 /

M.bovis

/ Rif/INAH / Gland / 20 / M / 2000 / On steroids
6 / MTB / INAH/Rif/Zin / Sputum / 33 / M / 2000 / Non-compliance
7 / MTB / pyrazinamide / Sputum / 35 / M / 2001 / Smear positive
8 / MTB / Streptomycin / BW / 78 / M / 2001 / Diabetic

Table 1. Resistant isolates 1997-2002. All isolates were tested for sensitivity to Rifampicin (Rif), isoniazide (INAH), Pyrazinamide (Zin), ethambutol and streptomycin. As M bovis is inherently resistant to pyrazinamide this is not included. The one case of MDR TB had defaulted on treatment.

Clusters are defined as one or more linked cases.

Graph 6. Known clusters. Confirmation of the extent of one large cluster was helped by DNA testing of isolates. The remaining clusters were family and close contacts. The clusters with 1 were cases known to have contact with an active TB case outside the SEHB.

3. Outcome data:

  • 151 (67%) are known to have completed treatment
  • 31(14%) are known not to have completed treatment (table 2)
  • 42 (19%) treatment outcome not available
  • 22 patients died, 1 directly due to TB, 4 possibly due to TB
  • Patients on chemoprophylaxis or with MOTTare not included.

Due to side effect of medication / 6
Died from other cause before treatment started / 2
Defaulted on treatment / 3
Died from TB / 1
Possible death from TB / 4
Died from other causes while on TB treatment / 11
Incidental postmortem finding-not cause of death / 2
Reason not recorded / 2

Table 2: Thirty one cases where treatment was not completed.

The most common reason was death due to some other cause.

Summary

Sixty-one (27%) of cases of Tuberculosis in the SEHB in the years 1997-2002 were sputum smear positive and so a potential source of infection to others, 32 (14%) cases had a past history of TB, 50 (22%) cases had a past history of contact with TB recorded, and 49 cases were part of known clusters. This is a reminder of the need to identify cases of TB as early as possible in the disease process in order to minimize transmission and the need for treatment to be closely monitored to ensure compliance with medication.

Tuberculosis continues to pose a threat to the public and to health care workers and will continue to require sufficient resources to maintain control of this disease.

Acknowledgement

This report is produced with data provide by the SEHB Area Medical Officers, Waterford Regional Hospital Microbiology Department, Hospital Clinicians and other hospital laboratories.