Ireland has seen a decline in incidence of mycobacterium tuberculosis (MTB) to 6/100,000 in Irish born residents in 2014. Early identification and treatment of active and latent cases remain the mainstay of TB control. A recent outbreak of TB in an island community illustrate the consequences of a single active case and the resources required for effective TB control.
We describe an outbreak of MTB on an Irish island (pop. 250). Medical charts and public health records were reviewed to assess clinical presentations, uptake and outcomes of screening for latent TB (LTB), and barriers to care.
Six cases of MTB infection were identified from December 2012- November 2014 (incidence 6/250 (2.4%)). Cases were genotypically identical, all occurring in Irish HIV negative men. The index case was symptomatic 3 months prior to diagnosis. Of the 6 cases, one was a household contact and 5/6 frequented the same bar. The index case and household contact presented with pulmonary MTB. The remaining 4/5 (80%) secondary cases had extra-pulmonary MTB (2/5 pleural TB, 1/5 TB lymphadenitis, 1/5 disseminated TB). After the third case, Mantoux screening was extended to the entire island, with 97% uptake (260/268). 48/260 (18.5%) met criteria for LTB. 15/48 (31.3%) agreed to LTB treatment, 30/48 (62.5%) opted for serial x-ray, 3/48 (6.25%) declined follow up. 2/5 secondary cases were initially diagnosed with LTB, refused treatment, presenting with active disease within 6 months. A third case initially had a borderline Mantoux (5mm) and presented 2 years later with disseminated MTB. Barriers to care included isolation, limited medical resources on the island, stigma and community resistance.
This outbreak in a semi-closed community illustrates the potential impact of a single case of MTB. The high net reproductive number with early secondary cases emphasizes the need to remain vigilant to the varying presentations of tuberculosis, in particular extra-pulmonary disease typical of early post-primary infection. Despite high acceptance of screening, community-related barriers likely accounted for the low uptake of LTB treatment and contributed to the number of active
D. O'donovan, None
A. O'regan, None
C. Higgins, None