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.