Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 14, Number 6—June 2008
Letter

Coxiella burnetii in Wild-caught Filth Flies

On This Page
Tables
Article Metrics
11
citations of this article
EID Journal Metrics on Scopus

Cite This Article

To the Editor: Coxiella burnetii, the agent of Q fever, is a bacterium and a potential agent of bioterrorism. The most frequent signs of infection in domestic animals are abortion and reduced fertility (1). Clinical signs of Q fever in humans vary from mild fevers to pneumonia, hepatitis, or death; atypical cases occur as other disorders, such as cholecystitis (1,2). Aerosols are the most common route of exposure, but oral transmission occurs (1).

Some flies feed on the feces, milk, carcasses, or blood of domestic animals that can be infected with C. burnetii. These flies regurgitate and defecate when feeding and are mechanical vectors of bacteria (3,4). Flies have been shown to harbor, mechanically transport, and even support the growth of C. burnetii (46). It is known that house flies (Musca domestica) are possible mechanical vectors of C. burnetii because this organism survived 32 days in house flies and viable bacteria were shed by flies for 15 days (4). There are no studies of C. burnetii in field-collected flies. To examine the prevalence of C. burnetii in field-collected flies, we tested flies from farms, forests, ranches, and zoos.

Flies that develop on animal dung, carcasses, feces, blood, or garbage are often called filth flies. Adult Calliphoridae, Hippoboscidae, Muscidae, and Sarcophagidae were collected from forests, zoos, ranches, and farms (Table). Flies were killed in 95% ethanol or by freezing. DNA was extracted from individual flies as described (7,8). A distilled water negative control was used for each extraction.

Individual DNA samples were tested, in duplicate, with a previously described TaqMan assay with a lower limit of detection of 1 C. burnetii organism (8). Positive and negative controls were used for all assays. Positive flies were verified by PCR and sequencing of 16S rRNA gene as described (9). Vouchers for each insect species were deposited in the Clemson University Arthropod Collection (Clemson, SC, USA), the University of Georgia Museum of Natural History (Athens, GA, USA), or the University of Wyoming Insect Collection (Laramie, WY, USA).

Five of 363 flies were positive for C. burnetii DNA (Table). These flies included Stomoxys calcitrans, in which the adults feed on animal and human blood, and the blowflies Lucilia coeruleiviridis and L. sericata. C. burnetii–positive flies were obtained from carrion (1/12, 8.3%), a garbage bin of elephant feces (3/18, 16.7%), and a barn at a ranch (1/55, 1.8%). We sequenced 1,100 bp of the 16S rRNA gene from select DNA extracts, which were 99% identical with that of C. burnetii strain NC 002971.

We detected DNA from C. burnetii in flies from a zoo, a ranch, and carrion in a forest. Laboratory data on house flies, which shed live C. burnetii for 15 days after exposure, suggest that related flies (e.g., S. calcitrans and Lucilia spp.) might also harbor viable C. burnetii. On the basis of our field data, S. calcitrans and Lucilia spp. should be studied as mechanical vectors of C. burnetii. Unlike many enteric bacteria, which require large inocula to cause disease, C. burnetii can be infectious at the level of 1 bacterium (10). If flies transmit C. burnetii, they pose an additional threat to human and animal health.

The role of the sheep ked (Melophagus ovinus) in maintenance or transmission of C. burnetii is unknown. This fly is an obligate ectoparasite of sheep. It feeds on sheep blood, and feces from sheep keds can accumulate in the wool of sheep. Testing of sheep keds from infected sheep would help understand whether keds play a role in the epidemiology of C. burnetii.

Top

Acknowledgment

We thank A. Fabian, C. Kato, and R. Priestly for laboratory assistance; K.D. Cobb, G. Johnston, and W. Yarnell for field collections; J. Andre for research permits; T. Kreeger for access to his facility; R. Massung for positive-control DNA; and G. Dahlem for identifying Ravinia spp.

Top

Mark P. Nelder*, John E. Lloyd†, Amanda D. Loftis‡1, and Will K. Reeves§Comments to Author 

Author affiliations: *Clemson University, Clemson, South Carolina, USA; †University of Wyoming, Laramie, Wyoming, USA; ‡Centers for Disease Control and Prevention, Atlanta, Georgia, USA; §US Department of Agriculture, Laramie;

Top

References

  1. Woldehiwet  Z. Q fever (coxiellosis): epidemiology and pathogenesis. Res Vet Sci. 2004;77:93100. DOIPubMed
  2. Hartzell  JD, Peng  SW, Wood-Morris  RN, Sarmiento  DM, Collen  JF, Robben  PM, Atypical Q fever in US soldiers. Emerg Infect Dis. 2007;13:12479.PubMed
  3. Nayduch  D, Noblet  GP, Stutzenberger  FJ. Vector potential of houseflies for the bacterium Aeromonas caviae. Med Vet Entomol. 2002;16:1938. DOIPubMed
  4. Hucko  M. The role of the house fly (Musca domestica L.) in the transmission of Coxiella burnnetii. Folia Parasitol (Praha). 1984;31:17781.PubMed
  5. Dhanda  V, Padbidri  VS, Mourya  DT. Multiplication of Coxiella burnetii in certain mosquitoes. In: Proceedings of the Symposium on Vectors and Vector-borne Diseases, Puri, Orissa, India. 1982. National Academy of Vector Borne Diseases. p. 69–73.
  6. Mourya  DT, Padbidri  VS, Dhanda  V. Mosquito inoculation technique for the diagnosis of Q fever employing an animal model. Indian J Med Res. 1983;78:2014.PubMed
  7. Kato  CY, Mayer  RT. An improved, high-throughput method for detection of bluetongue virus RNA in Culicoides midges utilizing infrared-dye-labeled primers for reverse transcriptase PCR. J Virol Methods. 2007;140:1407. DOIPubMed
  8. Loftis  AD, Reeves  WK, Szumlas  DE, Abbassy  MM, Helmy  IM, Moriarity  JR, Surveillance of Egyptian fleas for agents of public health significance: Anaplasma, Bartonella, Coxiella, Ehrlichia, Rickettsia, and Yersinia pestis. Am J Trop Med Hyg. 2006;75:418.PubMed
  9. Reeves  WK. Molecular genetic evidence for a novel bacterial endosymbiont of Icosta americana (Diptera: Hippoboscidae). Entomol News. 2005;116:2635.
  10. Hatchette  TF, Hudson  RC, Schlech  WF, Campbell  NA, Hatchette  JE, Ratnam  S, Goat-associated Q fever: a new disease in Newfoundland. Emerg Infect Dis. 2001;7:4139.PubMed

Top

Table

Top

Cite This Article

DOI: 10.3201/eid1406.071691

1Current affiliation: Private practice, Laramie, Wyoming, USA

Related Links

Top

Table of Contents – Volume 14, Number 6—June 2008

Comments

Please use the form below to submit correspondence to the authors or contact them at the following address:

Will K. Reeves, Agricultural Research Service, Arthropod-Borne Animal Diseases Research Laboratory, College of Agriculture, US Department of Agriculture, Department 3354, 1000 E University Ave, Laramie, WY 82071-2000, USA;

Send To

character(s) remaining.

Comment submitted successfully, thank you for your feedback.

Top

Page created: July 09, 2010
Page updated: July 09, 2010
Page reviewed: July 09, 2010
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
file_external