Development and infectivity of Anaplasma marginale in Dermacentor andersoni nymphs

Katherine M. Kocan From the Departments of Veterinary Pathology (Kocan), Veterinary Parasitology, Microbiology, and Public Health (Ewing), and Medicine and Surgery (Barron), College of Veterinary Medicine, and the Departments of Statistics (Claypool) and Entomology (Hair), Oklahoma State University, Stillwater, OK 74078.

Search for other papers by Katherine M. Kocan in
Current site
Google Scholar
PubMed
Close
 PhD
,
Theodora N. Yellin From the Departments of Veterinary Pathology (Kocan), Veterinary Parasitology, Microbiology, and Public Health (Ewing), and Medicine and Surgery (Barron), College of Veterinary Medicine, and the Departments of Statistics (Claypool) and Entomology (Hair), Oklahoma State University, Stillwater, OK 74078.

Search for other papers by Theodora N. Yellin in
Current site
Google Scholar
PubMed
Close
 MS
,
P. L. Claypool From the Departments of Veterinary Pathology (Kocan), Veterinary Parasitology, Microbiology, and Public Health (Ewing), and Medicine and Surgery (Barron), College of Veterinary Medicine, and the Departments of Statistics (Claypool) and Entomology (Hair), Oklahoma State University, Stillwater, OK 74078.

Search for other papers by P. L. Claypool in
Current site
Google Scholar
PubMed
Close
 PhD
,
Selwyn J. Barron From the Departments of Veterinary Pathology (Kocan), Veterinary Parasitology, Microbiology, and Public Health (Ewing), and Medicine and Surgery (Barron), College of Veterinary Medicine, and the Departments of Statistics (Claypool) and Entomology (Hair), Oklahoma State University, Stillwater, OK 74078.

Search for other papers by Selwyn J. Barron in
Current site
Google Scholar
PubMed
Close
 BVSc, MS
,
S. A. Ewing From the Departments of Veterinary Pathology (Kocan), Veterinary Parasitology, Microbiology, and Public Health (Ewing), and Medicine and Surgery (Barron), College of Veterinary Medicine, and the Departments of Statistics (Claypool) and Entomology (Hair), Oklahoma State University, Stillwater, OK 74078.

Search for other papers by S. A. Ewing in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
, and
Jakie A. Hair From the Departments of Veterinary Pathology (Kocan), Veterinary Parasitology, Microbiology, and Public Health (Ewing), and Medicine and Surgery (Barron), College of Veterinary Medicine, and the Departments of Statistics (Claypool) and Entomology (Hair), Oklahoma State University, Stillwater, OK 74078.

Search for other papers by Jakie A. Hair in
Current site
Google Scholar
PubMed
Close
 PhD

Click on author name to view affiliation information

SUMMARY

The development of Anaplasma marginale was studied in Dermacentor andersoni nymphs after they had fed on a calf with ascending Anaplasma infection. Gut tissues were collected on day 4 of tick feeding, from newly replete (fed) nymphs and on postfeeding days (pfd) 5, 10, 15, 20, and were processed for light and electron microscopy to determine density of A marginale colonies. Homogenates of gut tissues were prepared from nymphs collected on the same days and inoculated into susceptible, splenectomized calves to test for infectivity. Anaplasma colonies were detected in gut cells on pfd 5, 10, 15, and 20. Although colony density appeared to be higher on pfd 10 and 15, differences were not significant. Nymphal type-1 colonies were detected in highest numbers on pfd 5 and 10, transitional colonies were seen in highest numbers at pfd 10 and 15, and nymphal type-2 colonies were observed only on pfd 20. Gut homogenates that were collected from ticks at 4 days of feeding, when newly replete, and on pfd 20 caused anaplasmosis when injected into susceptible calves, but homogenates made from ticks collected on pfd 5, 10, and 15 were not infective. The data indicate that of the colony types of A marginale that develop in replete nymphs, nymphal type-1 and transitional colonies may contain organisms that are not infective for cattle.

SUMMARY

The development of Anaplasma marginale was studied in Dermacentor andersoni nymphs after they had fed on a calf with ascending Anaplasma infection. Gut tissues were collected on day 4 of tick feeding, from newly replete (fed) nymphs and on postfeeding days (pfd) 5, 10, 15, 20, and were processed for light and electron microscopy to determine density of A marginale colonies. Homogenates of gut tissues were prepared from nymphs collected on the same days and inoculated into susceptible, splenectomized calves to test for infectivity. Anaplasma colonies were detected in gut cells on pfd 5, 10, 15, and 20. Although colony density appeared to be higher on pfd 10 and 15, differences were not significant. Nymphal type-1 colonies were detected in highest numbers on pfd 5 and 10, transitional colonies were seen in highest numbers at pfd 10 and 15, and nymphal type-2 colonies were observed only on pfd 20. Gut homogenates that were collected from ticks at 4 days of feeding, when newly replete, and on pfd 20 caused anaplasmosis when injected into susceptible calves, but homogenates made from ticks collected on pfd 5, 10, and 15 were not infective. The data indicate that of the colony types of A marginale that develop in replete nymphs, nymphal type-1 and transitional colonies may contain organisms that are not infective for cattle.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 37 37 9
PDF Downloads 44 44 15
Advertisement