Results of a preliminary serological survey of small mammal populations for plague on the island of Hawaii

Since 1910 the District of Hamakua, Island of Hawaii, has been considered an endemic plague area. To obtain indirect evidence of plague infection in rodents and in the mongoose, serological surveys of the small mammal populations were undertaken. The passive microhaemagglutination test demonstrated the presence of positive reactors (titres of 1:16 and higher) in the sera of 2641 rodents and 385 mongooses tested. Positive percentages were: Rattus exulans, 1.5%; R. norvegicus, 1.9%; R. rattus, 0.6%; Mus musculus, 1.1%; and Herpestes auropunctatus, 12.5%. This study has proved the continued presence of a permanent reservoir of plague in indigenous rodent and mongoose populations after a period of 65 years since the introduction of plague into Hawaii and has demonstrated that the mongoose is an excellent indicator of plague infection.