**4. Clinical findings**

Throughout the world, louse infestation of ruminants is an important problem that impairs the growth and performance parameters among beef, dairy stocks and buffalos. Chewing lice feed on skin and hair debris as well as on skin secretions. The other species have mouthparts adapted for piercing the skin and suck blood.

Louse infestation has been reported to cause blood loss [9], anemia, anorexia, restlessness, weight reduction of as much as 25–30 kg, diminished milk production and development of stress [6, 10–13]. The blood-sucking lice mentioned above may also be carriers of different pathogens [14]. Host animals infested with blood-sucking lice tend to keep scratching, licking and biting their skin, thus causing hair loss and skin injuries to themselves. By rubbing their body against different objects, cattle infested with lice may damage fences or trees. Such stress can reduce weight gains and milk production for up to 10% and makes the animals more susceptible for other diseases. Cattle with hair loss may be discounted at the saleyards. Skin that has been irritated by lice has a rough surface with complete loss of hair in some areas, which gives the animals an unthrifty appearance and reduces both the slaughter value and the usability of skin and hide for industrial processing [15]. In the UK, analysis of hides in abattoirs resulted in more than 80% showing some degree of lice damage. In recent years, hide or fleece damage caused by lice has been increasingly recognized as a significant effect of lice infestations. The damage is described as areas of grain loss up to 3 mm diameter that are seen on dyed crust leather [16].

her lifetime. She deposits them one by one to single hairs. Incubation lasts 4–20 days. The eggs hatch and develop through three nymph stages to adults. Nymphs look like adults but are smaller. Adult life lasts for 2–6 weeks. Lice tend to prefer the white areas of black-and-white cattle. Off the host, most lice survive only for a few days. Survival of lice is reduced by warm

Lice infestations develop mostly in the colder season and peak in late winter and early spring. Skin temperature has also been correlated with the severity of louse infestation. Lice decline during the hotter season. Stabling the animals during the winter season favors overcrowding, which makes contact transmission easier. The poorer diet during winter weakens the natural defense of cattle against the lice infestations. The denser and more humid hair coat in winter

In spring, food improves quickly when the herds start grazing fresh pastures. The shorter hair and the exposure to the sun reduce skin humidity, and free grazing ends overcrowding in the winter quarters, which also diminishes transmission. As a consequence, lice infestation usually recedes spontaneously during the summer season. However, a few lice usually manage to survive in some animals that will re-infest the whole herd when it comes back to the winter

Lice spend their whole life on the same hosts: transmission from one host to another one is by contact. Transmission from herd to herd is usually through introduction of an infested animal, but flies or fomites may also occasionally transport lice. Up to 1–2% of the cattle in a herd can carry a high load of lice, even in the summer when high temperatures reduce the number of lice. These carrier animals are the source of reinfestation during the fall. Usually, they are a bull or a cow in poor body condition [8]. Winter housing provides the ideal conditions for

Throughout the world, louse infestation of ruminants is an important problem that impairs the growth and performance parameters among beef, dairy stocks and buffalos. Chewing lice feed on skin and hair debris as well as on skin secretions. The other species have mouthparts

Louse infestation has been reported to cause blood loss [9], anemia, anorexia, restlessness, weight reduction of as much as 25–30 kg, diminished milk production and development of stress [6, 10–13]. The blood-sucking lice mentioned above may also be carriers of different pathogens [14]. Host animals infested with blood-sucking lice tend to keep scratching, licking and biting their skin, thus causing hair loss and skin injuries to themselves. By rubbing their body against different objects, cattle infested with lice may damage fences or trees. Such stress can reduce weight gains and milk production for up to 10% and makes the animals more

weather, cattle self-grooming, loss of hair coat and good nutrition of the host [3, 4].

offers an excellent environment for lice development as well.

quarters for the next winter [3, 4].

82 Bovine Science - A Key to Sustainable Development

the transfer of lice between cattle.

adapted for piercing the skin and suck blood.

**4. Clinical findings**

**3. Epidemiology**

For all age classes of cattle, stressors such as high stocking density, poor feed quality, gestational status, and underlying health issues are often contributing factors to susceptibility and degree of infestation.

Factors determining the severity of infestation with blood-sucking lice include the animals' age and sex and also the season. Numerous studies have been conducted to investigate correlations between the distribution of lice and the age of host animals within herds. Occurrences of bovine pediculosis do not show seasonal variation in countries with a warm climate. However, in the temperate zone and in colder regions, the most severe infestations occur in late winter and early spring, when the weather is cold and damp and the animals have the thickest coat of hair. The coat of hair serves as a habitat and shelter for lice, and provides optimum conditions for their propagation. During the year, the highest increase in the louse population occurs when cattle or buffaloes are kept indoors for the winter. In late spring, the number of lice suddenly decreases. It then remains at a low average level during the summer months when the hair coat becomes thinner, which provides a less favorable habitat for lice, because the high temperature of the skin surface and direct exposure to sunlight reduce the intensity of their development [2, 15]. Other authors have also observed seasonal occurrences of pediculosis, reporting that the population of sucking lice starts to grow in late winter, reaches its peak in the spring and its nadir in the summer and autumn months. In India, the highest 'louse index' was found in January and the lowest in June [17]. According to the results obtained by Hussain et al., the louse population reaches its highest level in February, and the environmental conditions continue to be favorable for survival and propagation of lice in March and April [9].

In a survey conducted in Pakistan [18], the prevalence of lice was significantly (P < 0.05) higher in cattle than in buffaloes: 144 out of 600 randomly selected cattle (24%) and only 113 out of 600 randomly selected buffaloes (18%), kept under conditions identical to those of the cattle, proved to be infected. The prevalence of louse infestation in cattle has been reported by researchers from different countries [19–21] have reported varying prevalence rates of louse infestation in cattle in association with differences in the ecological, geographic and weather conditions. Animals kept in closed management systems are not exposed to direct sunlight, which favors the survival of lice. When cattle are kept in open barns, houses with outdoor runs or in free range management system, their skin surface is directly exposed to sunlight and consequently becomes drier, which reduces the survival chances of lice and decreases the intensity of their propagation [10]. A total of 762 water buffaloes were examined. *H. tuberculatus* was found in the 11.0% (14/127) of the farms and in the 4.5% (34/762) of the animals. The presence of *H. tuberculatus* should be routinely considered because it is a cause of serious health, production and economic damages in intensive breeding buffaloes [22]. According to our observations, the female host animals and, among them, the cows showed the most severe louse infestation. Larvae of the parasite accounted for only 0.3% and adult lice represented 3.2% of all the developmental stages recovered, while 96.4% of the stages found were louse eggs. The hair samples from the bulls yielded five adult lice and 83 louse eggs, while those from the cows yielded 78 adult lice, eight larvae and 2348 louse eggs. The hair samples from the buffalo heifers yielded 12 adult lice, two larvae and 641 louse eggs, while from those of young males, seven adult lice and 16 louse eggs were recovered [18].

*B. bovis* is the dominant species present, assessment of the neck and tailhead alone is sufficient to detect most infestations. If sampling indicates that *Haematopinus tuberculatus* is the dominant species present in the herds, hair samples were taken only from animals which the hair was covered with louse eggs that were easily visible with the naked eye. These hair samples

Although lice normally do not survive away from the host, it is possible to send live specimens by post if a suitably insulated container is used (warmed to 25°C beforehand if possible) and containing a generous quantity of suitable animal hair. Some biting lice can be maintained for at least 8 weeks and a new generation obtained *in vitro* if they are kept on filter papers in Petri dishes at 36–37°C. It is essential to maintain the humidity at 68% RH by the use of an appropriate solution of NaOH, sulfuric acid, or concentrated solution of NH4

For short-term tests, a solution of NaCl may be used, giving approximately 75% RH as a food supply, dried yeasts with powered hair and fresh skin scrapings is supplied; it is important that these should be fresh (no more than 6 days old unless deep frozen) and from the correct host species. This maintenance technique makes it possible to test the insecticide susceptibil-

Classical concentrates for dipping and spraying with traditional contact insecticides (mainly organophosphates, synthetic pyrethroids and amidines) are quite effective lousicides for cattle. However, such insecticides do not kill lice eggs (nits) and their residual effect is usually not long enough to ensure that immature lice are killed when hatching out of the eggs. A variety of compounds effectively control lice in cattle, including synergized pyrethrins, the synthetic pyrethroids cyfluthrin, permethrin, zeta cypermethrin, and cyhalothrin (including gamma- and lambda-cyhalothrin) (beef cattle only). Many pyrethroids are lyophilic, which assists the development of pour-on formulations with good distribution [28]. Natural pyrethrins are quickly degraded, while synthetic pyrethroids such as flumethrin and deltamethrin have greater stability and a relatively long period of action [29], but they do not affect all developmental stages of the louse life cycle. Organophosphates such as phosmet, chlorpyrifos (beef and nonlactating dairy cattle only), tetrachlorvinphos, coumaphos, and diazinon (beef and nonlactating dairy cattle only) are used against lice. Certain Brahman and Brahman-cross cattle have organophosphate hypersensitivity, which should be considered when selecting a treatment compound. The compounds such as macrocyclic lactones ivermectin, eprinomectin, and doramectin are also used to control lice in cattle. Injectable macrocyclic lactones will also control biting lice, since they reach the parasites through the

blood stream of the host. But control of chewing lice is usually incomplete<sup>2</sup>

are primarily effective against bloodsucking lice.

lations are effective against biting and bloodsucking lice, whereas injectable formulations

The interesting thing about it is that in the treatment of chewing or biting lice, *Werneckiella equi equi* (Denny, 1842) infestation in a foal stock in Hungary, which was treated with paste Eqvalan (MSD) (and Rintal Plus (Bayer)) at doses of

0.2 mg/kg (and 8.4 g/100 kg) body weight, respectively, after 13 days was not found with the nits of lice [30].

area on the side of the middle part of the neck.

NO<sup>3</sup> . 85

Louse Infestation of Ruminants

http://dx.doi.org/10.5772/intechopen.79257

. Pour-on formu-

were consistently collected from a 2 cm2

ity of strains from the field [18, 25–27].

**7. Treatment**

2
