Browsing by Author "Montenieri, John A."

Now showing 1 - 5 of 5
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    Early-phase Transmission of Yersinia pestis by Cat Fleas (Ctenocephalides felis) and Their Potential Role as Vectors in a Plague-endemic Region of Uganda
    (The American journal of tropical medicine and hygiene, 2008) Eisen, Rebecca J.; Borchert, Jeff N.; Holmes, Jennifer L.; Amatre, Gerald; Van Wyk, Kristen; Enscore, Russell E.; Babi, Nackson; Atiku, Linda A.; Wilder, Aryn P.; Vetter, Sara M.; Bearden, Scott W.; Montenieri, John A.; Gage, Kenneth L.
    In recent decades, the majority of human plague cases (caused by Yersinia pestis) have been reported from Africa. In northwest Uganda, which has had recent plague outbreaks, cat fleas (Ctenocephalides felis) have been reported as the most common fleas in the home environment, which is suspected to be a major exposure site for human plague in this country. In the past, C. felis has been viewed as only a nuisance-biting insect because limited laboratory studies suggested it is incapable of transmitting Y. pestis or is an inefficient vector. Our laboratory study shows that C. felis is a competent vector of plague bacteria, but that efficiency is low compared with another flea species collected in the same area: the oriental rat flea, Xenopsylla cheopis. On the other hand, despite its low vector efficiency, C. felis is the most common flea in human habitations in a plague-endemic region of Uganda (Arua and Nebbi Districts), and occasionally infests potential rodent reservoirs of Y. pestis such as the roof rat (Rattus rattus) or the Nile rat (Arvicanthisniloticus). Plague control programs in this region should remain focused on reducing rat flea populations, although our findings imply that cat fleas should not be ignored by these programs as they could play a significant role as secondary vectors.
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    Evaluation and Modification of Off-Host Flea Collection Techniques Used in Northwest Uganda: Laboratory and Field Studies
    (Journal of medical entomology, 2012) Borchert, Jeff N.; Eisen, Rebecca J.; Holmes, Jennifer L.; Atiku, Linda A.; Mpanga, Joseph T.; Brown, Heidi E.; Graham, Christine B.; Babi, Nackson; Montenieri, John A.; Enscore, Russell E.; Gage, Kenneth L.
    Quantifying the abundance of host-seeking ßeas is critical for assessing risk of human exposure to ßea-borne disease agents, including Yersinia pestis, the etiological agent of plague. Yet, reliable measures of the efÞcacy of existing host-seeking ßea collection methods are lacking. In this study, we compare the efÞcacy of passive and active methods for the collection of host-seeking ßeas in both the laboratory and human habitations in a plague-endemic region of northwest Uganda. In the laboratory, lighted “Kilonzo” ßea traps modiÞed with either blinking lights, the creation of shadows or the generation of carbon dioxide were less efÞcient at collecting Xenopsylla cheopis Rothchild and Ctenocephalides felis Bouche´ ßeas than an active collection method using white cotton socks or cotton ßannel. Passive collection using Kilonzo light traps in the laboratory collected signiÞcantly more X. cheopis than C. felis and active collection, using white socks and ßannel, collected signiÞcantly more C. felis than X. cheopis. In Þeld studies conducted in Uganda, Kilonzo traps using a ßashlight were similar in their collection efÞcacy to Kilonzo traps using kerosene lamps. However, in contrast to laboratory studies, Kilonzo ßea traps using ßashlights collected a greater number of ßeas than swabbing. Within human habitations in Uganda, Kilonzo traps were especially useful for collecting C. felis, the dominant species found in human habitations in this area.
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    Evaluation of Rodent Bait Containing Imidacloprid for the Control of Fleas on Commensal Rodents in a Plague-Endemic Region of Norther Uganda
    (Journal of medical entomology, 2010) Borchert, Jeff; Enscore, Russell E.; Eisen Rebecca J.; Atiku, Linda A.; Owor, Nicholas; Acayo, Sarah; Babi, Nackson; Montenieri, John A.; Gage, Kenneth L.
    In recent decades, the majority of human plague cases (caused by Yersinia pestis) have been reported from Africa. In an effort to reduce the risk of the disease in this area, we evaluated theefÞcacy of a host-targeted rodent bait containing the insecticide imidacloprid for controlling ßeas on house-dwelling commensal rodents in a plague-endemic region of northwestern Uganda. results demonstrated that the use of a palatable, rodent-targeted, wax-based bait cube was effective at reducing the prevalence of ßeas on commensal rodents and ßea burdens on these animals at day 7 postbait exposure, but lacked signiÞcant residual activity, allowing ßea populations to rebound in the absence of additional bait applications. Our results indicate the use of a palatable host-targeted bait block containing imidacloprid was an effective technique for quickly reducing ßea numbers on rodents in northwest Uganda and, thus, could be useful for lowering the potential risk of human ßea bite exposures during plague outbreaks if applied continuously during the period of risk
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    Flea Diversity as an Element for Persistence of Plague Bacteria in an East African Plague Focus
    (PLoS ONE, 2012) Eisen, Rebecca J.; Borchert, Jeff N.; Mpanga, Joseph T.; Atiku, Linda A.; MacMillan, Katherine; Boegler, Karen A.; Montenieri, John A.; Monaghan, Andrew; Gage, Kenneth L.
    Plague is a flea-borne rodent-associated zoonotic disease that is caused by Yersinia pestis and characterized by long quiescent periods punctuated by rapidly spreading epidemics and epizootics. How plague bacteria persist during interepizootic periods is poorly understood, yet is important for predicting when and where epizootics are likely to occur and for designing interventions aimed at local elimination of the pathogen. Existing hypotheses of how Y. pestis is maintained within plague foci typically center on host abundance or diversity, but little attention has been paid to the importance of flea diversity in enzootic maintenance. Our study compares host and flea abundance and diversity along an elevation gradient that spans from low elevation sites outside of a plague focus in the West Nile region of Uganda (,725–1160 m) to higher elevation sites within the focus (,1380–1630 m). Based on a year of sampling, we showed that host abundance and diversity, as well as total flea abundance on hosts was similar between sites inside compared with outside the plague focus. By contrast, flea diversity was significantly higher inside the focus than outside. Our study highlights the importance of considering flea diversity in models of Y. pestis persistence.
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    Identification of Flea Blood Meals Using Multiplexed Real-Time Polymerase Chain Reaction Targeting Mitochondrial Gene Fragments
    (The American journal of tropical medicine and hygiene, 2009) Woods, Michael E.; Montenieri, John A.; Eisen, Rebecca J.; Zeidner, Nordin S.; Borchert, Jeff N.; Laudisoit, Anne; Babi, Nackson; Atiku, Linda A.; Enscore, Russell E.; Gage, Kenneth L.
    is found in the West Nile region of Uganda and Democratic Republic of the Congo where flea vectors are often found inhabiting homes. We have developed a multiplexed, real-time polymerase chain reaction assay targeting mitochondrial genes that is capable of detecting blood meal sources in fleas collected off-host in East Africa. Laboratory tests showed that the assay is specific for the intended targets and has a detection limit below one picogram of DNA. Testing of wild-caught fleas from the Democratic Republic of Congo suggests that humans are at significant risk from flea-borne disease and implicates domestic animals including cats, chickens, and the black rat as potential sources of human exposure to fleas and flea-borne diseases. Future application of the assay will help us better define the ecology of plague in East Africa to implement effective control measures to combat the spread of disease.