Need for vaccination of sewer workers against leptospirosis and hepatitis A

This study compared the prevalence of Leptospira interrogans and hepatitis A virus (HAV) antibodies in serum samples from sewer workers and controls.

A blood sample was obtained from 76 of the 101 municipal sewer workers (75%) of Quebec City and from two controls matched to each for age and sex. Testing was done for antibodies against serovars of Leptospira icterohaemorragiae, bratislava, hardjo, grippotyphosa, and kennewicki (pomona) and hepatitis A.

Sewer workers had a greater prevalence of antibodies against leptospirosis than controls (12% v 2%, P = 0.003). In contrast, antibodies to HAV were not significantly more prevalent among workers than among controls (54% v 49%, P = 0.51). Prevalence of HAV antibodies increased significantly with age both among workers and controls (chi 2 for trend, P < 0.001). In contrast with younger workers, prevalence of HAV antibodies was greater among workers > or = 40 years than among their controls (81% v 65%, P = 0.04).

Leptospirosis continues to be a problem to sewer workers but hepatitis A is apparently no longer a risk. The likely explanation is that leptospira are still abundant in the sewage system in contrast with HAV, which is only rarely to be found in sewage as a result of the generalised decrease in incidence of hepatitis A in the past three decades. The decision to vaccinate sewer workers against hepatitis A should take into account that it is impossible to avoid all contact with sewage fluid and, despite the fact that the actual incidence of hepatitis A is low, there is a real possibility of sporadic exposure during a future outbreak.