Tuberculosis contact investigations in congregate settings in Rome, Italy: contribution of migration

Background

In middle to low incidence countries tuberculosis (TB) is known to concentrate in big cities as national incidence falls: in the last decade TB incidence in Rome metropolitan area and in Lazio region has been higher than the national estimates; TB incidence among foreign born fell by more than half despite remaining higher than among Italian born.

We aimed to describe the current dynamics of TB transmission among residents of our local health unit in Rome metropolitan area in order to drive specific TB control interventions at local level.

Methods

We retrospectively evaluated characteristics of TB cases and results of contact investigations among the residents of ASL Roma 2 in congregate settings over year 2018.

Results

Overall 217 TB cases were notified, of which 70.5% with pulmonary involvement. Male/female ratio was 2.4/1 and age group most affected was 25-44 among foreign born and >65 among natives. During the study period foreign born cases accounted for 65% of the total number of TB cases. 19/141 (13.5%) foreign born patients were hosted in a reception center. 479 exposed close contacts were screened, with no evidence of secondary TB disease transmission. No identifiable links were found among cases occurred in the same immigrant reception center.

Conclusions

Italian guidelines recommend symptom screening for TB and LTBI testing both of new entrants and of long term residents -including second–generation migrants- from high TB burden countries. These findings suggest that local public health efforts should prioritize the identification of reactivations of remotely acquired latent TB rather than of new postarrival infections acquired in the host county through local transmission.

Key messages

City-specific data on TB incidence trends among native and foreign-born residents help understanding the wider interaction between migration and TB. To prevent TB incidents in congregate settings remotely acquired latent TB should be targeted.

Legionella pneumophila in residential water supplies: environmental surveillance with clinical assessment for Legionnaires' disease

Although cases of community-acquired Legionnaires' disease have been epidemiologically linked to residential water supplies, the risk of acquiring Legionnaires' disease from exposure to Legionella pneumophila in residential water systems is uncertain. The residential water supplies of 218 members of the American Legion in six different geographical areas in Pittsburgh were cultured for L. pneumophila. Residents of the homes provided a recent medical history and a blood sample for detection of antibodies to legionella. A urine sample for legionella urinary antigen testing was also requested from individuals residing in legionella-positive homes and individuals with a positive antibody test. Six percent (14/218) of the homes yielded L. pneumophila (range within six areas 0-22%). Lower hot water tank temperature was significantly associated with legionella positivity (P less than 0.01). Analysis of water samples for mineral content showed no association between legionella positivity and concentrations of calcium and magnesium. Water samples from the area where 22% of the homes surveyed were positive for legionella had a higher iron content than water samples from the other areas tested. None of the individuals residing in legionella-positive homes showed elevated antibody titres to legionella or the presence of legionella antigen in urine. For the immunocompetent hosts, the risk of contracting Legionnaires' disease from exposure to contaminated household water supplies in the Pittsburgh area appears to be low.