Mass chemoprophylaxis for control of outbreaks of meningococcal disease

Abstract

Although vaccination is the main strategy used to control meningococcal disease outbreaks, mass chemoprophylaxis has also been used as an immediate response to outbreaks, either to supplement vaccination or when vaccination is not possible. However, public health guidelines regarding the use of mass chemoprophylaxis for outbreak control vary by country, partly because the impact of mass chemoprophylaxis on the course of an individual outbreak is difficult to assess. We have reviewed data for the use of mass chemoprophylaxis during 33 outbreaks that occurred both in military populations and in communities and non-military organisations. In most outbreaks, no additional cases of meningococcal disease occurred after mass chemoprophylaxis, or cases occurred only in individuals who had not received prophylaxis. A delay of several weeks was common before cases occurred among prophylaxis recipients. Overall, the outbreak reports that we reviewed suggest that mass chemoprophylaxis might provide temporary protection to chemoprophylaxis recipients during outbreaks.

Figure 1.. Reduction in N. meningitidis carriage after mass chemoprophylaxis during meningococcal disease outbreaks.

Data shown are the percent reduction in N. meningitidis carriage after use of mass chemoprophylaxis in response to meningococcal disease outbreaks. In five instances rifampicin was used; ciprofloxacin (bolded) was used in the remaining instance. Error bars are 95% confidence intervals (CI) for percent reduction in carriage in the target population calculated through the method of Zou and Donner. When exact number of carriers was not reported, carriers were estimated from reported percent carriage. Only reports where an entire population (not just carriers) was targeted for chemoprophylaxis are included. See Table S1 for number of specimens tested and carriage prevalence at each time point. ^£Two rounds of chemoprophylaxis were conducted; carriage was assessed before the first and after the second. ^§95% CI not calculated as population tested for carriage was reported as larger than population targeted for chemoprophylaxis.