3.5.2 Specific flea index (SFI)
Since oriental rodent fleas (X.cheopis ) received high public
health concern regarding their efficiency in amplification and
transmission of Y. pestis from rodent to rodent and from rodent
to human (Eisen and Gage, 2009; Maestas and Britten, 2017), we have
evaluated their specific flea index as one of the potential factor that
may cause risk for epizootic plague among rodents and eventually to the
society (Gage, 1999; Eisen et al ., 2012, 2020). It has been
reported that a specific flea index >1 for X.cheopison rats represents a potentially dangerous situation with respect of
increased plague risk to human in the event of an outbreak of plague
(Gage, 1999). Similarly an outbreak of human plague is more likely to
happen if the specific flea index is >5 (Singchai et
al , 2003).
Based on result obtained in this study, we found that specific flea
index of X.cheopis was equal to one (1.0 SFI) in plague foci
villages and less than 0.5 (<0.5 SFI) in non-plague foci
villages. Despite that, these indices do not really call for urgent
control of fleas in these areas, it provide the basic information to
understand how plague foci villages require more attention to prevent
situation from exceeding the risk level. The high specific flea index in
plague foci villages is probably due to high abundance of host of
oriental rodent fleas i.e. Rattus rattus and less frequentlyMastomys natalensis as compared to non-plague foci villages.