NRU :: Browsing by Author "Borchert, Jeff N."

Browsing by Author "Borchert, Jeff N."

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Bartonella Species in Invasive Rats and Indigenous Rodents from Uganda
(Vector-Borne and Zoonotic Diseases, 2014) Borchert, Jeff N.; Atiku, Linda A.; Mpanga, Joseph T.; Gage, Kenneth L.; Kosoy, Michael Y.; Billeter, Sarah A.
The presence of bartonellae in invasive rats (Rattus rattus) and indigenous rodents (Arvicanthis niloticus and Cricetomys gambianus) from two districts in Uganda, Arua and Zombo, was examined by PCR detection and culture. Blood from a total of 228 R. rattus, 31 A. niloticus, and 5 C. gambianus was screened using genus- specific primers targeting the 16S–23S intergenic spacer region. Furthermore, rodent blood was plated on brain heart infusion blood agar, and isolates were verified as Bartonella species using citrate synthase gene- (gltA) specific primers. One hundred and four fleas recovered from R. rattus were also tested for the presence of Bartonella species using the same gltA primer set. An overall prevalence of 1.3% (three of 228) was obtained in R. rattus, whereas 61.3% of 31 A. niloticus and 60% of five C. gambianus were positive for the presence The presence of bartonellae in invasive rats (Rattus rattus) and indigenous rodents (Arvicanthis niloticus and Cricetomys gambianus) from two districts in Uganda, Arua and Zombo, was examined by PCR detection and culture. Blood from a total of 228 R. rattus, 31 A. niloticus, and 5 C. gambianus was screened using genus-specific primers targeting the 16S–23S intergenic spacer region. Furthermore, rodent blood was plated on brain heart infusion blood agar, and isolates were verified as Bartonella species using citrate synthase gene- (gltA) specific primers. One hundred and four fleas recovered from R. rattus were also tested for the presence of Bartonella species using the same gltA primer set. An overall prevalence of 1.3% (three of 228) was obtained in R. rattus, whereas 61.3% of 31 A. niloticus and 60% of five C. gambianus were positive for the presence of Bartonella species. Genotypes related to Bartonella elizabethae, a known zoonotic pathogen, were detected in three R. rattus and one C. gambianus. Bartonella strains, similar to bacteria detected in indigenous rodents from other African countries, were isolated from the blood of A. niloticus. Bartonellae, similar to bacteria initially cultured from Ornithodorus sonrai (soft tick) from Senegal, were found in two C. gambianus. Interestingly, bartonellae detected in fleas from invasive rats were similar to bacteria identified in indigenous rodents and not their rat hosts, with an overall prevalence of 6.7%. These results suggest that if fleas are competent vectors of these bartonellae, humans residing in these two districts of Uganda are potentially at greater risk for exposure to Bartonella species from native rodents than from invasive rats. The low prevalence of bartonellae in R. rattus was quite surprising, in contrast, to the detection of these organisms in a large percentage of Rattus species from other geographical areas. A possible reason for this disparity is discussed of Bartonella species. Genotypes related to Bartonella elizabethae, a known zoonotic pathogen, were detected in three R. rattus and one C. gambianus. Bartonella strains, similar to bacteria detected in indigenous rodents from other African countries, were isolated from the blood of A. niloticus. Bartonellae, similar to bacteria initially cultured from Ornithodorus sonrai (soft tick) from Senegal, were found in two C. gambianus. Interestingly, bartonellae detected in fleas from invasive rats were similar to bacteria identified in indigenous rodents and not their rat hosts, with an overall prevalence of 6.7%. These results suggest that if fleas are competent vectors of these bartonellae, humans residing in these two districts of Uganda are potentially at greater risk for exposure to Bartonella species from native rodents than from invasive rats. The low prevalence of bartonellae in R. rattus was quite surprising, in contrast, to the detection of these organisms in a large percentage of Rattus species from other geographical areas. A possible reason for this disparity is discussed
Blood Meal Identification in Off-Host Cat Fleas (Ctenocephalides felis) from a Plague-Endemic Region of Uganda
(The American journal of tropical medicine and hygiene, 2013) Graham, Christine B.; Borchert, Jeff N.; Black IV, William C.; Atiku, Linda A.; Mpanga, Joseph T.; Boegler, Karen A.; Moore, Sean M.; Gage, Kenneth L.; Eisen, Rebecca J.
The cat flea, Ctenocephalides felis, is an inefficient vector of the plague bacterium (Yersinia pestis) and is the predominant off-host flea species in human habitations in the West Nile region, an established plague focus in Northwest Uganda. To determine if C. felis might serve as a Y. pestis bridging vector in the West Nile region, we collected on- and off-host fleas from human habitations and used a real-time polymerase chain reaction-based assay to estimate the proportion of off-host C. felis that had fed on humans and the proportion that had fed on potentially infectious rodents or shrews. Our findings indicate that cat fleas in human habitations in the West Nile region feed primarily on domesticated species. We conclude that C. felis is unlikely to serve as a Y. pestis bridging vector in this region.
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.
Efficacy of Indoor Residual Spraying Using Lambda-Cyhalothrin for Controlling Nontarget Vector Fleas (Siphonaptera) on Commensal Rats in a Plague Endemic Region of Northwestern Uganda
(Journal of medical entomology, 2014) Borchert, Jeff N.; Eisen, Rebecca J.; Atiku, Linda A.; Delorey, Mark J.; Mpanga, Joseph T.; Babi, Nackson; Gage, Kenneth L.; Enscore, Russell E.
Over the past two decades, the majority ofhumanplague cases have been reported from areas in Africa, including Uganda. In an effort to develop affordable plague control methods within an integrated vector control framework, we evaluated the efÞcacy of indoor residual spraying (IRS) techniques commonly used for mosquito control for controlling ßeas on hut-dwelling commensal rodents in a plague-endemic region of Uganda. We evaluated both the standard IRS spraying (walls and ceiling) and a modiÞed IRS technique that included insecticide application on not only on walls and ceiling but also a portion of the ßoor of each treated hut. Our study demonstrated that both the standard and modiÞed IRS applications were effective at signiÞcantly reducing the ßea burden and ßea infestation of commensal rodents for up to 100 d after application, suggesting that IRS could potentially provide simultaneous control of mosquito and ßeaborne diseases.
Epidemiology, Ecology and Prevention of Plague in the West Nile Region of Uganda: The Value of Long-Term Field Studies
(The American Journal of Tropical Medicine and Hygiene., 2021) Eisen, Rebecca J.; Atiku, Linda A.; Enscore, Russell E.; Mpanga, Joseph T.; Acayo, Sarah; Mead, Paul S.; Apangu, Titus; Yockey, Brook M.; Borchert, Jeff N.; Beard, Charles B.; Gage, Kenneth L.
Plague, a fleaborne rodent-associated zoonosis, is a neglected disease with most recent cases reported from east and central Africa and Madagascar. Because of its low incidence and sporadic occurrence, most of our knowledge of plague ecology, prevention, and control derives from investigations conducted in response to human cases. Long-term studies (which are uncommon) are required to generate data to support plague surveillance, prevention, and control recommendations. Here we describe a 15-year, multidisciplinary commitment to plague in the West Nile region of Uganda that led to significant advances in our understanding of where and when persons are at risk for plague infection and how to reduce morbidity and mortality. These findings provide data-driven support for several existing recommendations on plague surveillance and prevention and may be generalizable to other plague foci
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.
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.
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.

Browsing by Author "Borchert, Jeff N."

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