Sheep Ked Infestation

Sheep ked infestation is a parasitic condition caused by Melophagus ovinus, a wingless fly that spends its entire life cycle on sheep, feeding on blood and causing significant irritation, wool damage, and economic losses to sheep producers worldwide. Despite being commonly called the sheep tick, this organism is not a true tick but rather a highly specialized hippoboscid fly that has evolved to be completely dependent on its sheep host for survival. The flattened, leathery body of the sheep ked is distinctively adapted for movement through dense wool, and its piercing mouthparts enable blood feeding that sustains the parasite while causing discomfort and injury to the host animal.

Sheep keds affect sheep of all breeds across every sheep-producing region of the world, though their prevalence and impact vary with climate, management practices, and breed characteristics. The parasite thrives in temperate climates and reaches highest populations during cooler months when dense fleeces provide optimal habitat. Wool sheep with long, dense fleeces experience greater ked burdens than hair sheep breeds, and heavily fleeced individuals within breeds harbor more parasites than those with lighter fleeces. While sheep are the primary host, keds occasionally transfer to goats housed with infested sheep, though they do not establish persistent populations on goat hosts. The parasite does not survive for extended periods off the host, making transmission dependent on direct animal-to-animal contact.

The economic and welfare impact of sheep ked infestation extends across multiple dimensions of sheep production. Heavy infestations cause significant blood loss leading to anemia, reduced growth rates, and decreased productivity. The intense itching and irritation from ked feeding and movement through the fleece causes sheep to rub, bite, and scratch, damaging wool quality and reducing fleece value. Ked feces staining of wool, known as cockle, creates permanent discoloration that persists through processing and reduces wool grade. Hide damage from ked feeding leaves visible defects that reduce leather quality. The stress and discomfort of heavy infestation affects animal welfare and predisposes sheep to other health problems.

Sheep ked infestation is highly treatable with modern antiparasitic products, and strategic treatment programs can effectively eliminate keds from sheep flocks. Shearing dramatically reduces ked populations by removing their habitat and exposing survivors to environmental conditions and treatment products. Various topical and systemic treatments are highly effective when properly applied, though product selection must consider withdrawal times for meat and milk and any regulatory restrictions on specific products. Prevention through biosecurity measures, treatment of new arrivals, and strategic timing of interventions can maintain ked-free status in previously cleared flocks. Understanding ked biology and implementing integrated control programs protects sheep welfare while maintaining wool quality and economic returns.

The primary cause of sheep ked infestation is exposure to and colonization by Melophagus ovinus, the sheep ked or louse fly. This obligate parasite cannot survive away from sheep hosts for more than a few days, making transmission entirely dependent on direct contact between infested and uninfested animals. Adult keds transfer between sheep during close contact such as crowding in yards, sharing close confinement housing, nursing behavior between ewes and lambs, and breeding activities. Once established on a new host, female keds begin producing offspring that perpetuate and expand the infestation. Each female produces approximately ten to fifteen offspring during her five to six month lifespan, with the entire reproductive cycle occurring within the protective environment of the sheep's fleece.

While ked infestation is not genetically determined, certain breed and individual characteristics influence susceptibility and infestation intensity. Sheep breeds producing dense, long-stapled wool provide superior habitat for keds, supporting larger populations than breeds with shorter, more open fleeces. Fine wool breeds such as Merinos often carry heavier ked burdens than medium or coarse wool breeds. Hair sheep breeds including Katahdin, Dorper, and Barbados Blackbelly experience minimal ked infestation as their hair coats do not provide suitable ked habitat. Within breeds, individuals with denser fleece coverage, particularly around the belly, flanks, and legs, harbor more keds than those with lighter wool cover in these areas.

Environmental and management factors significantly influence ked population dynamics and infestation severity. Cooler temperatures favor ked survival and reproduction, with populations typically peaking in late winter and early spring before shearing. Warm, dry conditions reduce ked viability and slow reproduction. Extended intervals between shearings allow ked populations to build to high levels within the protection of long fleeces. Congregating sheep in confined spaces such as yards, sheds, and crowded pastures facilitates transmission between animals. Introduction of infested animals without quarantine and treatment allows establishment of keds in previously clear flocks. Failure to treat after shearing when remaining keds are vulnerable misses an important control opportunity.

Several risk factors increase individual animal and flock susceptibility to sheep ked infestation. Young lambs become infested through close contact with their mothers, and heavy infestation can develop rapidly in lambs nursing heavily infested ewes. Animals with compromised immune function or concurrent illness may be less able to resist ked establishment or control population growth. Nutritional stress reducing wool quality and density may actually decrease ked habitat quality, but the associated immunocompromise may offset this effect. Flock management practices including shearing schedules, treatment protocols, and biosecurity measures are the dominant factors determining flock-level ked status.

The pathophysiology of sheep ked infestation involves both direct effects of ked feeding and indirect effects of the host response. Each ked feeds on blood multiple times daily, with heavy infestations consuming sufficient blood to cause measurable anemia. Ked saliva injected during feeding contains anticoagulants and other substances that provoke inflammatory and immune responses in the skin. Mechanical irritation from ked movement through the fleece and the piercing of skin during feeding causes pruritus driving self-trauma behaviors. Ked feces deposited within the fleece contain partially digested blood that stains wool and may serve as a substrate for secondary microbial growth. The cumulative stress of chronic infestation affects cortisol levels, immune function, and overall animal wellbeing.

Early warning signs of sheep ked infestation may be subtle and easily overlooked without specific attention to this possibility. Affected sheep may display increased restlessness and scratching behaviors before visible signs of heavy infestation become apparent. Close parting of the wool, particularly along the flanks, belly, and neck, may reveal individual keds moving through the fleece or attached to the skin surface. Wool may appear slightly disturbed or less organized in areas of ked activity. Small, reddish-brown spots of ked feces visible at the base of wool fibers provide early evidence of infestation even when keds themselves are difficult to locate. Changes in grazing behavior, with more time spent rubbing against fence posts, trees, or other objects, may indicate developing irritation.

Common symptoms of established sheep ked infestation reflect the irritation, blood loss, and wool damage caused by significant parasite burdens. Infested sheep display pronounced rubbing, scratching, and biting at their fleeces, sometimes causing visible wool loss and skin damage in heavily affected areas. Wool becomes disorganized and damaged in appearance, with the characteristic yellow-brown staining of cockle visible when fleeces are parted. Keds themselves become readily visible during fleece examination, appearing as flat, brown, wingless insects approximately five to seven millimeters in length moving through the wool. Heavily infested animals may develop patchy wool loss, particularly on the neck, shoulders, and flanks where ked populations concentrate.

Behavioral changes in sheep with ked infestation reflect the constant irritation and discomfort these parasites cause. Affected sheep spend excessive time engaged in comfort behaviors including rubbing against available surfaces, turning to bite at their sides, and scratching with hind feet. Normal grazing patterns become disrupted as animals interrupt feeding to address their discomfort. Social behaviors may change, with infested animals either seeking contact with flockmates for mutual grooming or becoming irritable and avoiding close contact. Sleep and rest patterns may be disturbed by persistent itching. Ewes with heavy infestations may become less attentive to lambs, and lambs nursing infested ewes may show signs of distress from the irritation transferred during nursing contact.

Physical signs of sheep ked infestation extend beyond the presence of the parasites themselves. Skin examination reveals small papules and areas of erythema where keds have been feeding, and more severe skin lesions develop in cases of heavy infestation or secondary infection. Wool quality deterioration includes fiber breakage, reduced staple strength, and the distinctive yellow-brown cockle staining that reduces fleece grade and value. Weight loss or poor weight gain reflects the metabolic cost of chronic parasitism and reduced time spent grazing. Pale mucous membranes indicating anemia develop in heavily infested animals experiencing significant blood loss. Poor body condition despite adequate nutrition suggests parasitic drain on animal resources.

Symptom progression in untreated ked infestations follows predictable patterns related to ked population growth and seasonal factors. Initial light infestations may produce minimal symptoms while ked populations build. As numbers increase through reproduction, irritation and wool damage become progressively more apparent. Peak populations in late winter and early spring correspond with maximum clinical impact just before shearing. Lambs born to infested ewes become infested within days of birth and may develop heavy burdens rapidly due to their small size and close contact with mothers. Without intervention, generations of keds perpetuate infestation through successive years with populations rebuilding after each shearing.

Emergency symptoms requiring immediate veterinary intervention are uncommon with sheep ked infestation alone but may develop in severe cases or when secondary complications occur. Profound anemia indicated by very pale or white mucous membranes, weakness, and exercise intolerance in heavily infested animals, particularly lambs, warrants urgent assessment and treatment. Extensive skin damage with secondary bacterial infection causing cellulitis, abscessation, or systemic illness requires antibiotic therapy alongside antiparasitic treatment. Severe self-inflicted trauma resulting in significant wounds or fly strike affecting damaged skin needs immediate attention. Any infested animal showing signs of systemic illness, rapid deterioration, or failure to respond to standard treatment should receive veterinary evaluation to identify complicating factors.

Clinical examination provides straightforward diagnosis of sheep ked infestation in most cases. Visual inspection of parted wool reveals keds as flat, brown, wingless insects moving through the fleece near the skin surface. Characteristic ked feces appear as small yellow-brown specks at the base of wool fibers. Examination should focus on preferred sites including the neck, shoulders, flanks, and belly where ked populations concentrate. Pupae attached to wool fibers near the skin appear as dark, oval structures approximately four millimeters in length. The presence of multiple life stages, including adult males and females, recently deposited pupae, and emerged adults, indicates established, reproducing infestation.

Diagnostic confirmation typically does not require laboratory testing given the readily identifiable nature of sheep keds. However, examination of collected specimens under magnification allows definitive identification and differentiation from other external parasites. Microscopic examination reveals the characteristic features of Melophagus ovinus including the flattened body, vestigial wing stubs, specialized mouthparts for blood feeding, and distinctive leg structures adapted for gripping wool fibers. In research or diagnostic laboratory settings, keds may be preserved in alcohol for detailed examination or submission to parasitologists for confirmation. Blood testing may reveal anemia in heavily infested animals, though this finding is nonspecific.

Differential diagnosis distinguishes ked infestation from other conditions causing pruritus and wool damage in sheep. Lice infestations, caused by biting lice such as Bovicola ovis or sucking lice such as Linognathus species, produce similar symptoms but the parasites are much smaller and readily distinguished from keds on close examination. Sheep scab caused by Psoroptes ovis mites causes intense itching and wool loss but mites require microscopic examination of skin scrapings for identification. Fleece rot and lumpy wool are bacterial conditions affecting wool quality but do not cause the pruritus associated with ked infestation. Photosensitization causes skin damage on unpigmented, sun-exposed areas rather than the fleece-covered regions favored by keds. External irritants or allergies may cause rubbing behavior but lack the identifiable parasites of ked infestation.

Flock-level assessment helps determine the extent of ked problems and guides control program planning. Random sampling of animals from different groups and ages provides estimates of infestation prevalence and intensity across the flock. Examination of recently shorn fleeces may reveal ked feces staining and other evidence of infestation that is being addressed. Assessment of historical ked problems, previous control efforts, and current treatment protocols identifies gaps in management contributing to persistent infestations. Evaluation of biosecurity practices, new animal introduction procedures, and contact with neighboring flocks helps identify sources of infestation or reinfestation. This comprehensive assessment informs development of strategic control programs addressing both immediate treatment needs and long-term prevention.

Emergency treatment for sheep ked infestation is rarely necessary as the condition does not pose immediate life-threatening risks in most cases. However, heavily infested animals showing signs of severe anemia, significant self-trauma, or secondary complications warrant priority treatment. Separating heavily infested animals from uninfested flock members reduces transmission while treatment takes effect. Supportive care including ensuring adequate nutrition, reducing stress, and monitoring for secondary problems accompanies antiparasitic treatment. Lambs with severe infestations acquired from heavily infested mothers may require special attention given their small body size and vulnerability to blood loss from parasitism.

Medical management of sheep ked infestation employs various antiparasitic products applied topically or administered systemically. Plunge dipping remains an effective treatment method, with sheep fully immersed in tanks containing approved insecticide solutions that penetrate fleece and contact keds throughout their habitat. Pour-on products applied along the backline distribute through the fleece and provide effective ked control with convenient application. Spray treatments using approved insecticides can be applied to shorn animals or those with shorter fleeces. Systemic treatment with injectable avermectin or milbemycin products provides ked control through blood feeding, killing parasites as they ingest treated blood. Product selection must consider meat and milk withdrawal times appropriate for the production system, and all label directions must be followed carefully. Only products approved for use in sheep and registered for ked control in the relevant jurisdiction should be used.

Strategic timing of treatment maximizes effectiveness against sheep keds. Treatment at shearing exploits the reduced ked habitat and increased product contact achieved when fleeces are removed or shortened. Off-shears treatment is particularly effective because remaining keds are exposed on the skin surface without protective wool cover. Treatment three to four weeks after shearing addresses any keds that survived initial treatment and any pupae that emerged after treatment, as most products do not kill pupae. Pre-lambing treatment of ewes reduces transmission to newborn lambs and limits ked buildup during the vulnerable early postnatal period. Fall treatment before winter housing prevents population expansion during the period of close animal contact and dense fleece conditions favoring ked reproduction.

Supportive care measures enhance treatment effectiveness and promote animal recovery. Ensuring adequate nutrition supports immune function and recovery from blood loss. Providing appropriate shelter and bedding reduces stress during treatment and recovery. Addressing any secondary skin infections with topical or systemic antimicrobials prevents complications. Monitoring treated animals confirms treatment effectiveness and identifies any animals requiring retreatment. Environmental management including cleaning housing areas and equipment reduces any transient ked survival in the environment, though environmental treatment is less critical than for many other parasites given the ked's limited survival away from hosts.

Flock treatment protocols aim for complete ked elimination rather than simple population reduction. Treating all animals in the flock simultaneously prevents transmission from untreated to treated individuals. Ensuring complete fleece coverage during topical treatment applications contacts keds throughout their habitat. Repeat treatments address emerging adults from pupae that survived initial treatment. Quarantine and treatment of all new arrivals before flock introduction prevents reintroduction of keds to cleared flocks. Documentation of treatment dates, products used, and treatment outcomes informs future decision making and regulatory compliance.

Treatment decisions balance immediate control needs with economic considerations and regulatory requirements. The cost of treatment products and application labor must be justified by expected benefits in wool quality, animal productivity, and welfare improvement. Withdrawal times affect marketing flexibility and must be incorporated into treatment timing decisions. Organic or naturally raised production systems may have restrictions on permitted treatment products requiring alternative approaches. Veterinary consultation helps producers select appropriate products and protocols for their specific production systems and ked problems. Documentation of treatment decisions, products used, and withdrawal dates supports regulatory compliance and quality assurance programs.

Recovery timelines following effective ked treatment depend on initial infestation severity and the extent of associated damage. Ked populations decline rapidly following effective treatment, with most adult keds dying within days of exposure to appropriate antiparasitic products. Pruritus and associated rubbing behaviors decrease noticeably within one to two weeks as irritation resolves. Skin lesions from ked feeding and self-trauma heal over two to four weeks in uncomplicated cases. Wool quality improvements require regrowth of undamaged fiber, with full recovery taking until the next shearing cycle. Anemia in heavily infested animals resolves over several weeks as animals replace lost red blood cells.

Post-treatment care and monitoring confirm treatment success and identify any animals requiring additional intervention. Fleece examination two to three weeks after treatment should reveal no surviving keds if treatment was effective. Any animals with surviving keds require retreatment with appropriate product and technique adjustments. Monitoring body condition and mucous membrane color in previously anemic animals confirms physiological recovery. Assessment of wool quality at subsequent shearing evaluates whether cockle staining has resolved and fiber quality has returned to normal. Continued vigilance for signs of reinfestation enables rapid response if keds are reintroduced to the flock.

Prognosis factors influencing recovery outcomes include initial infestation severity, treatment effectiveness, and prevention of reinfestation. Light to moderate infestations detected and treated promptly carry excellent prognosis for complete recovery. Heavy infestations with significant anemia or wool damage require longer recovery periods but generally resolve fully with appropriate treatment. Treatment failures due to inadequate product coverage, resistance issues, or failure to address pupae may result in persistent or recurring infestation requiring modified approaches. Prevention of reinfestation through biosecurity measures determines whether treatment gains are maintained or flocks become reinfested from external sources.

Return to production considerations following ked treatment focus on wool quality recovery and observance of withdrawal periods. Wool harvested from recently infested sheep may show residual cockle staining and quality defects until new growth replaces damaged fiber. Shearing may reveal hidden wool damage not apparent on fleece examination. Marketing decisions should account for potential quality reductions and appropriate grading adjustments. Meat and milk withdrawal periods associated with treatment products must be observed before animals or products enter the food chain. Documentation of treatment dates and products used supports compliance verification and quality assurance requirements.

Prevention of sheep ked infestation centers on maintaining ked-free flock status through biosecurity and strategic treatment. Closed flock management, avoiding introduction of outside animals, eliminates the primary route of ked introduction. When new animals must be introduced, strict quarantine with examination and treatment before flock contact prevents ked entry. Maintaining separation from neighboring flocks, avoiding shared grazing, and preventing fence-line contact with potentially infested animals reduces transmission risk from external sources. Treatment of all animals returning from shows, sales, or breeding loans before rejoining the main flock prevents introduction of keds acquired during absence.

Strategic treatment protocols maintain ked-free status in cleared flocks and prevent population buildup in endemic situations. Annual treatment at shearing takes advantage of optimal treatment timing when fleeces are removed. Follow-up treatment three to four weeks post-shearing addresses emerged pupae and ensures complete elimination. Pre-lambing treatment of ewes prevents transmission to newborn lambs and reduces reproductive ked populations. Treatment of lambs before weaning and mixing with other groups prevents spread to naive animals. Coordination of treatment timing with neighbors and shared grazing contacts reduces reintroduction pressure from external sources.

Environmental and management practices support ked prevention efforts. Reducing stocking density decreases contact transmission opportunities. Avoiding overcrowding in handling facilities, housing, and yards during management activities limits transmission during periods of close contact. Adequate nutrition maintaining good body condition supports natural resistance and maintains fleece quality. Regular shearing at appropriate intervals prevents the dense, long fleece conditions that favor ked population growth. Clean, well-ventilated housing with good bedding supports overall animal health and reduces stress that might compromise resistance.

Quarantine and testing protocols provide systematic approaches to preventing ked introduction. All new arrivals should be isolated for minimum three weeks with thorough fleece examination for keds and other external parasites. Treatment of all new animals during quarantine regardless of examination findings provides insurance against light infestations that might be missed. Examination before release from quarantine confirms treatment effectiveness. Documentation of source flock ked status, quarantine dates, and treatments administered supports biosecurity program verification. Avoidance of purchases from sources with known ked problems reduces introduction risk.

Integrated pest management approaches combine multiple strategies for optimal ked control. Biological control through maintaining healthy animals with robust immune function and good fleece condition creates unfavorable conditions for ked establishment. Cultural control through management practices including shearing schedules, stocking density, and biosecurity reduces ked transmission and reproduction opportunities. Chemical control through strategic antiparasitic treatment eliminates existing infestations and prevents population buildup. Monitoring through regular flock examination detects emerging problems before they become established. Integration of these approaches provides more reliable control than reliance on any single strategy and reduces selection pressure for resistance development.

Daily management and monitoring for sheep ked prevention integrates parasite surveillance into routine flock observations. Regular examination of individual animals during handling for other purposes allows opportunistic detection of ked infestation. Observation of flock behavior identifies increased rubbing, scratching, or other signs suggesting developing problems. Awareness of seasonal patterns, with higher ked risk in late winter and early spring, focuses attention during high-risk periods. Documentation of any ked observations, even incidental findings in individual animals, triggers investigation and response before flock-wide problems develop.

Housing and environmental management support ked control within comprehensive flock health programs. Adequate space and ventilation in housing facilities reduces stress and contact transmission. Clean bedding maintains coat quality and general health. Avoidance of overcrowding during handling and yarding minimizes transmission opportunities during necessary congregation. Facility design allowing animal flow without excessive crowding reduces contact during routine management activities. Cleaning and maintenance of handling facilities, though less critical for ked control than for other parasites, supports overall parasite management programs.

Flock health programs incorporating ked prevention coordinate external parasite control with other health management activities. Integration of ked treatment with other post-shearing activities such as vaccination and drenching improves efficiency. Coordination of ked control with other external parasite management including lice and fly strike prevention provides comprehensive protection. Record keeping systems tracking treatment dates, products, and outcomes support program evaluation and planning. Regular program review and adjustment based on monitoring results and changing conditions maintains effectiveness.

Record keeping supports ked management program effectiveness and compliance requirements. Individual and flock treatment records document dates, products, doses, and withdrawal information. Monitoring records track examination findings and ked detection over time. Biosecurity records document quarantine procedures for introduced animals. Program evaluation records assess control success and guide improvements. These records support quality assurance programs, regulatory compliance verification, and informed management decision making.

Economic considerations in ked management justify prevention investments through cost-benefit analysis. The cost of annual preventive treatment programs is generally modest compared to wool quality losses from established infestations. Cockle staining can reduce fleece value by several percent, quickly exceeding treatment costs in commercial wool flocks. Productivity losses from reduced growth rates and poor condition add to economic impact. Treatment labor costs factor into program economics, with efficient application methods reducing per-animal costs. Prevention program investment provides more predictable returns than reactive treatment of established infestations, supporting consistent flock productivity and profitability.

High-risk breeds for sheep ked infestation are those producing dense, fine wool that provides optimal ked habitat. Merino sheep and their derivatives, selected for fine wool with high density and length, support larger ked populations than coarser-wooled breeds. Rambouillet and similar fine wool breeds share this susceptibility due to similar fleece characteristics. Breeds with heavy fleece coverage extending well down the legs, belly, and face provide more extensive ked habitat. British longwool breeds with dense, long fleeces experience significant ked burdens under favorable conditions. Any breed or individual with exceptionally heavy wool cover faces elevated ked risk compared to lighter-fleeced animals.

Production type significantly influences ked risk across sheep breeds and management systems. Wool production enterprises prioritizing fleece quality and quantity face greater economic impact from ked damage than meat-focused operations. Show flocks maintaining longer fleeces for exhibition purposes provide extended periods of optimal ked habitat. Stud flocks where high individual animal value justifies intensive management may implement more aggressive prevention programs. Commercial meat lamb operations with frequent shearing or terminal hair sheep crosses experience minimal ked impact. Production system differences influence both ked prevalence and the economic justification for control programs.

Hair sheep breeds demonstrate dramatically lower ked susceptibility due to their unsuitable coat characteristics. Katahdin, Dorper, St. Croix, Barbados Blackbelly, and other hair sheep breeds lack the wool cover that keds require for survival and reproduction. Keds may temporarily transfer to hair sheep in contact with infested wool sheep but cannot establish persistent populations. Crossbred animals with intermediate fleece characteristics show intermediate susceptibility. Selection pressure toward reduced wool cover in meat-focused breeding programs may inadvertently reduce ked susceptibility. Recognition of breed differences in ked susceptibility informs management decisions including breeding objectives, treatment protocols, and biosecurity requirements.

Commonly co-occurring conditions with sheep ked infestation often reflect shared management factors or parasite impacts. Lice infestations, particularly with Bovicola ovis, frequently accompany ked infestations in flocks with inadequate external parasite control. Internal parasite burdens may be elevated in flocks where overall parasite management is neglected. Fleece rot and bacterial skin infections may develop in fleeces damaged by ked activity and rubbing. Poor body condition from multiple parasitic drains and reduced grazing time affects many animals in heavily parasitized flocks. The stress of chronic parasitism may predispose to other infectious diseases and reduce vaccine responses.

Conditions with similar symptoms requiring differentiation from ked infestation include other causes of pruritus and wool damage. Sheep scab caused by Psoroptes ovis mites produces severe itching and wool loss but requires skin scraping for mite identification and is a notifiable disease in many jurisdictions. Lice infestations cause similar rubbing behavior but the much smaller lice require close examination for identification. Fleece rot causes wool discoloration and damage without the pruritus and visible parasites of ked infestation. Photosensitization affects sun-exposed unpigmented skin rather than fleece-covered areas. Allergic or contact dermatitis may cause focal irritation and rubbing. Careful examination including fleece parting, skin inspection, and parasite identification distinguishes these conditions.

Complications and sequelae of sheep ked infestation primarily relate to wool quality impacts and secondary problems arising from self-trauma. Cockle staining permanently marks wool fibers, persisting through processing to affect final product quality. Wool break from stress may occur during heavy infestations, reducing staple strength and processing value. Skin damage from rubbing and ked feeding predisposes to bacterial dermatitis requiring antibiotic treatment. Fly strike may target areas of damaged, moist skin or fecal soiling associated with ked infestation. Severe anemia in heavily infested lambs may compromise growth and survival. Economic losses from reduced wool value, decreased productivity, and treatment costs constitute the primary sequelae of poorly managed ked infestations.