ESTIMATION OF VECTOR INFECTIVITY RATES FOR PLAGUE BY MEANS OF A STANDARD CURVE-BASED COMPETITIVE POLYMERASE-CHAIN-REACTION METHOD TO QUANTIFY YERSINIA-PESTIS IN FLEAS
Bj. Hinnebusch et al., ESTIMATION OF VECTOR INFECTIVITY RATES FOR PLAGUE BY MEANS OF A STANDARD CURVE-BASED COMPETITIVE POLYMERASE-CHAIN-REACTION METHOD TO QUANTIFY YERSINIA-PESTIS IN FLEAS, The American journal of tropical medicine and hygiene, 58(5), 1998, pp. 562-569
Citations number
35
Categorie Soggetti
Public, Environmental & Occupation Heath","Tropical Medicine
The prevalence of infectivity within a vector population is a critical
factor in arthropod-borne disease epidemiology but it is difficult to
estimate. In the case of bubonic plague, infective flea vectors conta
in large numbers of Yersinia pestis within a bacterial mass that block
s the flea's foregut, and only such blocked fleas are important for bi
ologic transmission. A bacterial quantitation method could therefore b
e used to assess the prevalence of plague-infective (blocked) fleas in
a population. We developed a standard, curve-based, competitive polym
erase chain reaction (PCR) procedure to quantitate Y. pestis in indivi
dual fleas. The quantitative PCR (Q-PCR) method equaled a colony count
reference method in accuracy and precision when evaluated using mock
samples and laboratory-infected fleas. The Q-PCR was more reliable tha
n colony count, however, for field-collected fleas and for blocked fle
as collected after their death. In a sample of fleas collected from a
prairie dog colony in the aftermath of a plague epizootic, 48% were in
fected but less than 2% contained numbers of Y. pestis indicative of b
lockage. The method provides a means to monitor plague epizootics and
associated risks of flea-borne transmission to humans, and is applicab
le to the study of other vector-borne diseases.