Throat swabs were taken from 204 Malay pilgrims 18-72 days before their departure for the 2001 Hajj pilgrimage. Repeat swabs were taken from 84% of the pilgrims up to 45 days after their return.
Seventeen per cent of pilgrims were menningococcal carriers, with 90% carrying the W135 clone - the strain that caused an international outbreak of meningococcal disease during the Hajj 2000. Carriage was significantly higher in pilgrims who had not taken antibiotics.
The returning pilgrims reported between 1 and 10 people living in their household. The level of meningococcal carriage in 233 of these contacts was 8.2%, of whom 42% were carrying the W135 clone.
Many countries currently give meningococcal vaccine (covering A and C strains) to Hajj pilgrims, say the authors. However, vaccination with the quadrivalent meningococcal vaccine (also covering W135) should become mandatory for all Hajj pilgrims and be considered for their household contacts.
Transmission of this clone from vaccinated Hajj returnees to their unvaccinated household contacts was substantial, putting contacts at particular risk of developing invasive disease, they add.
"Our findings support a policy of administering antibiotics to pilgrims before their return to their countries of origin to eradicate carriage and protect household contacts," they conclude.