Studies on horizontal transmission of bovine leukosis

Abstract

SummaryA group of five newborn calves and a second group of seven calves of different breeds with a minimum age of six weeks, were placed in contact with animals with clinical cases of bovine leukosis for a period of five years. Among the newborn calves, one --a "Fleckvieh ''1 --developed tumorous leukosis in which many lymph nodes, the heart and the pylorus were affected. Two others in this group --also "Fleckvieh" --have moderately elevated lymphocyte counts, one of them developed enlarged prescapular lymph nodes. Those cattle brought in contact with diseased animals at a minimum age of six weeks remained --4 of them were Holsteins --normal throughout the course of the experiment. It is suggested that 1) neonatal cattle are more susceptible than those that are six week of age or older and 2) that the "Fleckvieh'-breed may be just as susceptible to leukosis as the Holstein one. It does not seem to have an inherited resistance againgt leukosis. ZusammenfassungZwei Gruppen yon Rindern verschiedenen Alters wurden mit Leukosekiihen in Isolierst/illen gehalten. Die eine Gruppe mit 5 Tieren war neugeboren, die andere mit 7 Tieren in einem Mindestalter yon 6 Wochen in Kontakt gekommen. Die Rassenverteilnng ist in den Tabellen festgehalten. Drei Tiere der Gruppe, die neugeboren in Kontakt kam, zeigen nach 5 Jahren Kontakt Ver/~nderungen: Ein Fleckviehrind kam mit tumorSser Leukose nieder, die beiden anderen --auch Fleckviehtiere --zeigen m/~l~ig erhShte Lymphozytenwerte, eines davon auch vcrgrSSerte Buglymphknoten. Die Tiere der Gruppe, die sp/~ter in Kontakt kamen, weisen keine Ver/s auf, die auf das Vorliegen einer leukotischen Erkrankung schliel~en lassen kSnnten. Daraus wird geschlossen, dab 1) neugeborene K/~Iber empfiinglicher sind als/~ltere Tiere, 2) Fleckviehtiere genauso empf/~nglieh sein kSnnen wie schwarzbunte und keine genetisch bedingte Resistenz gegen Leukose besitzen.

Epidemiology of natural transmission of bovine leukemia virus infection / by Mark Cy Thurmond.

“…In a crowded situation, transmission may occur either by aerosol (Van Der Maaten and Miller, 1978c) or by contact (Dechambre et al . , 1968;Maas-Inderwiesen et al, 1978;Miller and Van Der Maaten, 1978a;Straub, 1971Straub, , 1978aWilesmith et al . , 1980).…”

“…Newborn calves were more likely to develop leukosis when placed in close contact with leukotic cows (Straub, 1971 Infection rates increased during winter months in one herd studied, suggesting transmission associated with indoor housing conditions (VJilesmith et al., 1980). Limiting physical contact by vacating a stall between animals or by placing a single fence between animals appeared to retard transmission of infection (Miller and Van Der Maaten, 1978a).…”

“…, 1968;Maas-Inderwiesen et al . , 1978;Straub, 1971Straub, , 1978aMiller and Van Der Maaten, 1978a;Wilesmith et al . , 1980).…”

Leucose enzoótica bovina e vírus da leucemia bovina

“…O contágio (animal-animal) pode ocorrer de forma natural, mas requer um íntimo e prolongado contato físico, uma vez que animais separados por mais de dois metros de distância não transmitem a infecção (STRAUB, 1978). Porém, foi observada uma transmissão facilitada em animais mantidos confinados durante o inverno (WILESMITH, 1980).…”

Determination of Lymphocyte Count Necessary for Isolating Bovine Leukaemia Virus (BLV) from BLV‐Infected Cattle and Correlation between Lymphocyte Count and Antibody Titre

“…Although no mode of horizontal transmission has been fully elucidated, the phenomenon occurs as a result of transfer of BLV-infected B cells to other cattle through some mechanism. When lymphocytes from BLV-infected cattle are experimentally inoculated into a non-infected individual, the number of lymphocytes necessary for transmission varies with individual infected cattle (4, 6,9,10,11). The individual number of lymphocytes which is used for transmission, even if small, is considered to be of importance in BLV transmission in herd.…”