Crowded households, low income and education increase leprosy in contacts

Objectives:
What are the risk factors of leprosy in contacts?

Study design:
This review article included 23 cohort studies and 1 cross-sectional study.
Most of the studies had been conducted in Brazil and India.
The follow-up period ranged from 1 to 20 years and the publication covered the period from 1991 to 2019.
The sample ranged from 68 to 28,092 participants.
19 cohorts (79%) scored ≥ 7, indicating a low risk of bias.

Results and conclusions:
The investigators found illiteracy significantly increased risk of leprosy in contacts with 48% [RR = 1.48, 95% CI = 1.22 to 1.79].

The investigators found living in the same house significantly increased risk of leprosy in contacts with 141% [RR = 2.41, 95% CI = 1.87 to 3.10].

The investigators found leprosy with high bacillary load significantly increased risk of leprosy in contacts with 140% [RR = 2.40, 95% CI = 1.69 to 3.41].

The investigators found seropositivity to the Mycobacterium leprae PGL-1 (phenolic glycolipid-1) antigen significantly increased risk of leprosy in contacts with 254% [RR = 3.54, 95% CI = 2.21 to 5.67].

The investigators found presence of the bacillus in the bloodstream significantly increased risk of leprosy in contacts with 10.61-fold [RR = 10.61, 95% CI = 4.74 to 23.77].

The investigators found negative Mitsuda reaction significantly increased risk of leprosy in contacts with 2.68-fold [RR = 2.68, 95% CI = 1.76 to 4.07].

The investigators found immunization with BCG (bacillus Calmette-Guérin) vaccine had a protective effect against leprosy.

The investigators concluded that young and adults, who live with patients in crowded households, have lower income and low education have a higher risk of leprosy in contacts. The meta-analysis confirms the greatest risk for illiterate contacts.

Original title:
Factors associated with the development of leprosy in contacts: a systematic review and meta-analysis by Niitsuma ENA, de Caux Bueno I, […], Lana CF.

Link:
https://www.scielo.br/j/rbepid/a/6yRXLPSd7gnJ7RTFqJ5mqTb/?lang=en

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