Cattle lice in New Zealand: observations on the prevalence, distribution and seasonal patterns of infestation

A longitudinal study of a natural lice infestation in growing cattle over two winter periods

A group of 61 cattle which were naturally infested with lice was followed over two winter periods. Data were collected on the number of lice found at various body sites over this period. Summary statistics were produced and due to the repeated measured and hierarchical structure of the data, multi-level analysis was used to model the population dynamics of Bovicola bovis and assess the influence of the various hierarchical levels. A four level Poisson model was produced-level one, the individual number of lice at each parting; level two, the body site examined (shoulder, midline or rump); level three, the time of the inspection and level four, the animal. Seasonal fluctuation in lice numbers was modelled using a cosine function transformation of time. A seasonal pattern was seen in both years with lice counts higher in the first than the second year. The midline area was the most sensitive to detection of B. bovis. Variance contributed by the individual animal was less than that contributed by the body site examined and the time of the inspection. The model suggested that lice numbers within the shoulder and rump sites were near random following a Poisson distribution, but aggregation of lice occurred at the midline site with the distribution between animals following a Negative Binomial Pattern. The midline site was the most sensitive site for detecting B. bovis. Infestation numbers were higher in the first winter when cattle were younger. In the second winter, there was no difference in lice numbers between cattle exposed to infection for the first or second time.

A longitudinal study of a natural lice infestation in growing cattle over two winter periods

A group of 61 cattle which were naturally infested with lice was followed over two winter periods. Data were collected on the number of lice found at various body sites over this period. Summary statistics were produced and due to the repeated measured and hierarchical structure of the data, multi-level analysis was used to model the population dynamics of Bovicola bovis and assess the influence of the various hierarchical levels. A four level Poisson model was produced--level one, the individual number of lice at each parting; level two, the body site examined (shoulder, midline or rump); level three, the time of the inspection and level four, the animal. Seasonal fluctuation in lice numbers was modelled using a cosine function transformation of time. A seasonal pattern was seen in both year's with lice counts higher in the first than the second year. The midline area was the most sensitive to detection of B. bovis. Variance contributed by the individual animal was less than that contributed by the body site examined and the time of the inspection. The model suggested that lice numbers within the shoulder and rump sites were near random following a Poisson distribution, but aggregation of lice occurred at the midline site with the distribution between animals following a Negative Binomial Pattern. The midline site was the most sensitive site for detecting B. bovis. Infestation numbers were higher in the first winter when cattle were younger. In the second winter, there was no difference in lice numbers between cattle exposed to infection for the first or second time.

Keratoconjunctivitis and periorbital papillomatosis associated with heavy periorbital infestation by the tail louse Haematopinus quadripertusus in heifers

Heifers (Israeli-Holstein), aged 12-18 months, permanently maintained in open barns on an inadequate nutritional regime were found to be moderately to heavily infested by Haematopinus quadripertusus, the tail louse. The severely infested heifers showed keratoconjunctivitis and periorbital papillomatosis. Two treatments with an alpha-cypermethrin pour-on product 14 days apart controlled the lice, and were followed by alleviation of the inflammation and regression of the papillomas.

Eradication of lice in cattle

The purpose of this field study was to develop and evaluate eradication as a strategy to control lice in cattle. Thirty-three herds of cattle were selected and observed during a period of two and a half years. Before eradication, biting lice (Damalinia bovis) were present in 94% of the herds and 27% of the animals. Sucking lice (Linognathus vituli) were present in 42% of the herds and 5% of the animals. These levels were very similar to those reported from other countries in Northern Europe. The eradication strategy was successful in 28 of 33 herds, but lice were still present in 5 herds 3 to 6 months after treatment. Biting lice were present in all these 5 herds, sucking lice were present in 3 herds. During the next 12 months, nine of the 28 herds were reinfected with lice. Six herds were reinfected with just biting lice, 2 herds with just sucking lice and one herd was reinfected with both. There was no significant difference between the 2 louse species regarding the risk of unsuccessful eradication or reinfection. The only significant risk factor for reinfection was either purchase of livestock or use of common pasture, combined with failure in pre-treatment of newly introduced animals.

Morphology of the leather defect light flecks and spots

The skin histology and the scanning electron microscope morphology of the hide defect light flecks and spots after tanning were studied in 11 steers infested with biting lice (Damalinia bovis). Nine steers from herds free of lice were used as controls. Skin biopsies from 6 of the animals in the lice infested group showed mild to moderate hyperkeratosis and moderate perivascular to diffuse dermatitis with infiltration of mainly mononuclear cells and some eosinophilic granulocytes. The steers were slaughtered at an age of 18 to 23 months. Light flecks and spots occurred on all examined hides from the infested group after tanning. No examined hides from the control group demonstrated similar damage. Both light microscopic examination of sections of tanned hide with light flecks and spots and scanning electron microscopy of the same defects showed superficial grain loss and craters with a irregular fibre base encircled by smooth and intact grain. The association between louse infestation at an early age and damage of hides following slaughter 6 to 15 months later, suggested that louse infestations lead to a prolonged or lifelong weakening in the dermis. This weakening may cause superficial grain loss during the tanning process.

Variation in the level of grain defect light flecks and spots on cattle hides

The occurrence of hide damage light flecks and spots was determined on tanned hides from 28 herds during a period of 8 to 12 months. Light flecks and spots are described as small areas of grain loss up to 3 mm in diameter that are seen on dyed crust cattle leather. Damage was found on 75.8% of all hides. The neck and shoulders were the anatomical region with the highest prevalence of damage. Sixty-eight per cent of all hides had light flecks and spots in this region. The forelimbs and dewlap were the anatomical region with the second highest occurrence with a prevalence of 39.1%. This distribution corresponded to the known distribution of lice in cattle. No significant differences were observed in age, sex, prevalence of lice in the herd assessed in March or infestations with different lice species. The frequency of light flecks and spots varied significantly during the year. The frequency was highest in the late winter and early spring, decreased significantly during the summer and was lowest in the autumn. This variation supported the importance of lice in the development of light flecks and spots and suggested a relatively long healing period for the damages induced by lice.

Prevalence of lice on dairy cattle in England and the bordering counties of Wales

A postal questionnaire was used to collect information on the prevalence of lice on cattle on a random sample of dairy farms in England and the bordering counties of Wales. Replies were received from 1040 (52.8 per cent) of the 1970 farms which were mailed. Fifty per cent of farmers reported having ever seen or suspected lice in their herds and 29 per cent reported possible infestations in the winter of 1996/97. Visits were made to 24 farms in the south west of England during February 1998. Twelve of the farmers said that they had seen or suspected lice in their herd since October 1997, and that lice were more frequently observed on the adult cattle. However, examination revealed lice on 18 of the 24 farms, and adult cattle were the least likely group to be infested.

Therapeutic efficacy of zeta-cypermethrin pour-on for the treatment of biting and sucking lice in cattle under field conditions

OBJECTIVE

To assess the efficacy of zeta-cypermethrin pour-on to control cattle lice.

DESIGN

Five field trials in south-eastern Australia.

PROCEDURE

Zeta-cypermethrin pour-on, deltamethrin pour-on and pour-on vehicle were applied to groups of 10 cattle. Lice were counted before treatment and 14, 28, 42 and 56 days after treatment.

RESULTS

Zeta-cypermethrin pour-on given at 2.5 mg/kg was equivalent to, or marginally more effective than a deltamethrin pour-on at 0.75 mg/kg. It eliminated B bovis and H eurysternus and gave good control of L vituli and S capillatus. Zeta-cypermethrin at 1 mg/kg gave good control of B bovis and H eurysternus but was not satisfactory against L vituli and S capillatus.

CONCLUSION

Zeta-cypermethrin pour-on, given at 2.5 mg/kg, is an effective treatment for cattle lice control. Zeta-cypermethrin, and other synthetic pyrethroid pour-ons, are the treatment of choice to control B bovis.