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Infections are reported occasionally in Geophilic species mammals including livestock antimicrobial 220 buy stromectol 3mg amex, especially in some fi M virus alert buy stromectol 3mg with visa. It is the most frequently isolated occasionally in other species virus 38 buy generic stromectol 3 mg on line, especially rabbits geophilic dermatophyte in animals antibiotic vegetables buy stromectol in india. This organism infects the skin, but does not invade this dermatophyte is thought to be uncommon in hairs. Anthropophilic species fi Trichophyton equinum, adapted to horses, is an Anthropophilic dermatophytes are reported important cause of dermatophytosis in this species. Potential predisposing factors, such as tumors or many species of animals, especially rodents and treatment with immunosuppressive drugs, were reported in some cases. The hairs are Dermatophytes usually grow only in keratinized tissues typically broken at the base, giving the appearance of such as hair, nails and the outer layer of skin; the fungus having been shaved. The center of the lesion usually stops spreading where it contacts living cells or areas of contains pale skin scales in the early stage, giving it a inflammation. In areas with varying degrees of alopecia, scaling, crusts and later stages, the area is often covered by a crust and the erythema, and may or may not be pruritic. Individual lesions may coalesce to form affected area are usually brittle and break near the skin large, irregular patches. Occasionally, dermatophytes may die at the center of persicolor typically causes localized or generalized scaling a lesion and that area resolves, leaving a circular lesion with with little erythema and minimal alopecia. Some degree of folliculitis dermatophytosis can include kerions (localized severe occurs in most cases; papules or pustules involving the hair inflammation with swollen, boggy skin oozing pus) and follicle or conical dilation of the hair follicle ostium are pseudomycetomas. Onchomycosis may occur concurrently suggestive of dermatophytosis in small animals. Asymptomatic infections are also common, particularly in Although dermatophytosis is often self-limited in dogs, adult animals. Many cats infected with dermatophytes have few or no Generalized cases in adult dogs usually occur in lesions. Long-haired adults, in particular, can be subclinical immunosuppressed animals, especially those that have carriers or have only minimal signs, such as patchy areas of hyperadrenocortictropism or have been treated with short stubble, alopecia, scales or erythematous plaques, corticosteroids. More apparent cases tend Horses to be seen in kittens, with the early lesions often found on In horses, most dermatophyte lesions are found in areas the face, ears and paws. They usually begin as scales, affected areas may develop a thin, grayish white small patches of raised hairs, and progress to hair loss, with crust or a thick, moist scab. They may or may not be variable amounts of scaling, erythema, crusting and pruritic. Kerions may occur in some that have been reported in cats include miliary dermatitis animals, especially on the face. Severe cases of dermatophytosis, be seen, with small crusted lesions especially on the flanks. Lesions may coalesce, especially where concurrently in cats with dermatophytosis; the nails may be the skin is abraded from tack. Cattle In some cats, dermatophytosis may appear as one or In cattle, dermatophytosis varies from small focal more firm, subcutaneous nodules known as lesions to extensive generalized skin involvement. The pseudomycetomas, Pseudomycetomas tend to occur in initial lesions may be discrete, scaly and alopecic with long-haired cats, especially Persians, and are most often grayish-white crusts, and tend to appear on the face and found on the back and the neck. Some cats, but not others, have often on the chest and limbs, and bulls on the dewlap and concurrent cutaneous signs such as alopecia and scaling. Some areas may become suppurative True mycetomas have also been reported, though rarely. Lesions resembling light brown scabs Uncomplicated dermatophyte lesions are usually selfmay also be seen; when these scabs fall off, they leave an limiting within a few weeks to a few months in short-haired © 2004-2013 The clinical signs usually resolve by immunohistochemistry from systemic lesions in a spontaneously in 2 to 4 months. Sheep and goats Communicability Dermatophytosis tends to be seen in show lambs, but Most animal dermatophytes are readily transmitted to appears to be uncommon in production flocks. The most other susceptible hosts, including humans, by contact and noticeable signs are usually circular, alopecic areas with contamination of the environment. Swine Post Mortem Lesions Click to view images Pigs may develop a wrinkled lesion covered by a thin, Gross post-mortem lesions are usually identical to brown, easily removed scab, or a spreading ring of those in live animals; with the exception of inflammation. Dermatophyte infections are often pseudomycetomas and mycetomas, dermatophytes are asymptomatic in adult swine. There may be combination of direct microscopic examination, culture and areas of partial or complete alopecia, erythema, scales, and Wood’s lamp examination. A Wood’s lamp examination for fluorescence can be helpful in detecting some species of dermatophytes, such as Rabbits M. Not all strains of these Focal alopecia, with erythema, crusts, scales and scabs, organisms exhibit fluorescence. Certain topical preparations is initially seen mainly around the eyes, nose, ears and may mask the fluorescence, and alcohol can either suppress dorsal neck. The lesions may later spread to other areas of it or cause non-specific fluorescence. Microscopic examination of skin scrapings or plucked Hedgehogs hairs may reveal hyphae or arthroconidia. Hyphae rounding up into arthroconidia are diagnostic; however, hyphae alone Asymptomatic infections are common in hedgehogs. A longer clearing time can be helpful when the especially the comb, are often affected in fowl. The lesions hair is thicker and more heavily pigmented, or if the sample may include white crusts or plaques and hyperkeratosis. Various stains such as Although feathers may be lost in birds, they are not chlorazol black E, Parker blue-black ink, Swartz-Lamkin infected. In practices where fluorescence Reptiles microscopy is available, calcofluor white staining can be Reptiles are not usually affected by the dermatophytes used. Clinical should be taken from active lesions, as for microscopic signs reported during a Trichophyton outbreak in iguanas examination. Nail beds and claws are cultured in cases of included scaling, crusting, thickening of the skin and onchomycosis. This animal died of an undetermined in asymptomatic animals suspected of being carriers, illness, soon afterward. Cultures are usually incubated at room temperature (20– Drugs available to treat dermatophytosis in animals 28fiC), but higher temperatures can be used when certain include topical antifungal creams or shampoos, and organisms. The same treatment principles apply often become visible within 1-2 weeks but, some species in animals as people; however, practical considerations grow more slowly and may require longer to appear. However, the mycelial growth they can decrease contamination and transmission to others. In addition, the color change may be used in large animals, due to the cost of these drugs and the delayed with certain dermatophytes such as M. The side effects asymptomatic animals, caution must be used to distinguish of systemic drugs should also be taken into consideration infection from contamination of the coat with organisms when choosing a treatment plan. It may aid the penetration of Dermatophyte species can be identified by the colony topical drugs, as well as remove infected hairs. However, it morphology; the appearance of microconidia, macroconidia may also result in trauma to the skin and help disseminate and other microscopic structures; biochemical the infection. If the animal is clipped, this should be done characteristics such as urease production; and nutritional with care. Microconidia and macroconidia can be used to crusts, which should be removed by gentle brushing. Pseudomycetomas and mycetomas are also reported to be the thickness of the wall, shape and number of difficult to treat, often recur after surgery, and may not macroconidia vary with the species. Nevertheless, some cases have been produce microconidia and smooth, thin-walled, cigar treated successfully with drugs and/or surgery. Macroconidia are rarely seen with Animals should be isolated until the infection resolves. This organism does not produce environments such as kennels, catteries and animal shelters. Specialized tests, such as the ability to penetrate hairs in vitro, or mating tests performed at Prevention reference laboratories, may occasionally be used in the To prevent the introduction of dermatophytes into differentiation process. Some organisms can be acquired by Histology may be used in some cases, especially in contact with infected soil. Dermatophytes can be difficult to eradicate Treatment from environments such as kennels, catteries and animal Healthy animals often have self-limiting infections that shelters.
Some authors consider tinea barbae to antibiotics reduce swelling purchase 3 mg stromectol fast delivery be a form inflammatory bacteria en el estomago sintomas purchase stromectol line, and in some cases suppurative virus 46 order 3mg stromectol mastercard, lesions virus 300 fine remove stromectol 3 mg on line, of tinea faciei, rather than a separate condition. While some lesions may resemble those of tinea corporis, others have Tinea corporis little or no scaling or lack raised edges. In addition, the Tinea corporis, or ringworm, occurs on the trunk and areas of erythema may be indistinct. Infections presentations, tinea faciei is often confused with other skin often spread to the neck and wrists of adults in contact with diseases that affect the face. The symptoms include burning, pruritus, and abscesses, exophytic nodules, and pseudomycetomas erythematous lesions with scales, raised, sharply (granulomatous or pyogranulomatous masses surrounding demarcated borders and central clearing. Although pseudomycetomas can also occur vesicles are sometimes found at the edges of the lesion. Dissemination to Macerated, moist exudative forms or lesions with an internal organs. Immunosuppressed patients dry lesions with little scaling and an annular form are more may also be extensively infected with species that rarely characteristic of chronic cases. The same fungi can cause tinea cruris and tinea pedis, and the Communicability two conditions may be present concurrently. Dermatophytes acquired from animals can be transmitted between people, but this is uncommon and the Tinea pedis and tinea manuum number of transfers is limited. In contrast, anthropophilic Tinea pedis is usually caused by anthropophilic dermatophytes are readily spread from person to person. Another Diagnosis is based on the history, physical form of tinea pedis (the chronic, erythematosquamous or examination, and microscopic examination of scrapings and “moccasin” form) appears as scaling of the soles and lateral hairs from the lesions, sometimes in conjunction with surfaces of the feet, with variable degrees of inflammation fungal culture and other techniques such as Wood’s lamp and dryness. A third form of tinea pedis is characterized by examination and histology of the tissues. Organisms that exhibit fluorescence include affect one hand, although involvement of both hands is some strains of the zoophilic dermatophytes M. In this form, the palms become diffusely dry, scaly quinckeanum, as well as a few anthropophilic species, such and erythematous. Tinea manuum is most the most common agents in some regions, are not revealed often caused by anthropophilic dermatophytes, particularly T. Certain topical preparations may mask rubrum (cases are frequently an extension of athlete’s foot) the fluorescence, and alcohol can either suppress it or cause but occasional cases may be caused by zoophilic organisms non-specific fluorescence. Dermatophytes can often be detected by microscopic erinacei, or the geophilic organism M. Tinea unguium Hyphae rounding up into arthroconidia are diagnostic, but Tinea unguium (or onchomycosis) is a dermatophyte hyphae alone could be caused by other fungi, including infection of the nails. In hairs, arthroconidia may be found outside opaque, discolored, broken and dystrophic nails. Toenails are scrapings should be taken from the edge of the lesion, and affected more often than fingernails, and individual nails hairs should be plucked (not cut) from this area. Nail scrapings are generally taken patches to almost complete breakdown of the nail. Most from the nail bed, or from deeper portions of the nail after infections are caused by anthropophilic Trichophyton removing the outer layers (except in cases where the species, particularly T. Various stains such as chlorazol black E, Parker blue-black ink, Swartz-Lamkin Dermatophytes in immunosuppressed stain or Congo red stain may be added. Fluorescence individuals microscopy, using calcofluor white or other stains, can also In immunosuppressed individuals with impaired cellbe used to visualize dermatophyte structures. In rare cases, they may also the infection and targeting preventive measures © 2004-2013 Culture may also be necessary if the diagnosis Treatment should consider sources of reinfection, such is uncertain, or the infection is resistant to standard as pets, family members or other close contacts. However, recommendations vary in the literature, authors suggest treating all family members when the case and uncomplicated cases are not always cultured in practice. Samples for culture include hair, skin and nail samples, as for microscopic examination. Colony morphology can with infected animals should be limited, and gloves and differ with the medium. Descriptions are usually based on protective clothing should be used if these animals are Sabouraud agar, but dermatophyte medium or other fungal handled. Dermatophyte Better surveillance, improved living conditions and species can be identified by the colony morphology; the improved treatments can decrease the overall prevalence appearance of microconidia, macroconidia and other of anthropophilic dermatophytes, while hygiene, and microscopic structures; biochemical characteristics such as prevention of contact are helpful in individual cases. Some fungal cultures from infected Dermatophyte infections are common in people, people are negative. For example, tinea cruris is more Dermatophyte infections are treated with a variety of common in hot climates and in people who wear tight topical and oral antifungal drugs. In immunocompetent patients, topical agents are Most dermatophyte infections are not serious in healthy usually effective in cases that are limited to glabrous skin people, although some conditions are easier to treat than. Infections in glabrous skin usually resolve within 2(oral) antifungal drugs may be necessary in severe cases, or 4 weeks with treatment. In contrast, dermatophytosis of the if the infection does not respond to treatment or reappears. These infections are usually treated with addition, damaged nails do not always return to a normal systemic antifungals, although topical lotions or shampoos appearance even if the fungal infection is eliminated. Topical agents skin damaged by interdigital fungal infections, and are a may also be used to treat asymptomatic carriers or prevent particular concern in diabetics. Tinea capitis is reported to be more difficult to Dermatophytosis has the potential to be more serious in treat when it is caused by M. The most europeus) and the African hedgehog (Atelerix common agents vary with the host and the geographic albiventris). It is seen in pet hedgehogs as well as region, and may also be affected by management practices animals in the wild. However, lizards, snakes (green anacondas, Eunectes murinus) and an it is considered to be a camel-associated isolate in olive ridley sea turtle (Lepidochelys olivacea). Zoophilic dermatophytes fi Trichophyton simii affects nonhuman primates, but fi Microsporum canis is the most common species of some authors believe the primary host is a grounddermatophyte in cats and dogs, with cats dwelling animal. It has also been reported from considered to be the most important reservoir other mammals and birds. This organism is also found regularly in fi Trichophyton verrucosum, which is adapted to horses and rabbits, and it has been reported in cattle, is the most important dermatophyte in this other animals including cattle, sheep, goats, species. Isolates that appear to be especially sheep, goats, South American camelids adapted to horses were previously called and camels, but it can also be found occasionally Microsporum equinum, but were moved to M. Successful treatment of these premises must be resolve within a few months, but treatment can speed based on good environmental control, as well as treatment recovery, prevent the lesions from spreading, and decrease of symptomatically and asymptomatically infected animals. In one htm region of Norway, where 95% of herds participated, the prevalence of cattle ringworm decreased from 70% to 0% National Institutes of Health over a period of 8 years. Clinical PhD, Veterinary Specialist from the Center for Food dermatophytosis is also thought to be more common in Security and Public Health. Most infections in healthy Agriculture Animal and Plant Health Inspection Service animals heal spontaneously within one to a few months. Infections can be more development of resources for initial accreditation training. Dermatophytes can be isolated from animals with or References without clinical signs. Among livestock, dermatophytes are particularly Beguin H, Goens K, Hendrickx M, Planard C, Stubbe D, Detandt M. This disease usually becomes endemic Beguin H, Pyck N, Hendrickx M, Planard C, Stubbe D, Detandt in cattle herds, where it most often affects animals under a M. The lesions tend to develop in cattle when they interdigitale revisited: a multigene phylogenetic approach. Iorio R, Cafarchia C, Capelli G, Fasciocco D, Otranto D, Canine dermatophytosis caused by an anthropophilic species: Giangaspero A. Dermatophytoses in cats and humans in molecular and phenotypical characterization of Trichophyton central Italy: epidemiological aspects. Kano R, Edamura K, Yumikura H, Maruyama H, Asano K, A pictorial [monograph online]. The new species concept in Virkon-S against Microsporum canis for environmental dermatophytes-a polyphasic approach.
Transmission can occur from the bite or scratch of a cat or dog or antibiotics with anaerobic coverage discount 3 mg stromectol with visa, less commonly bacteria jokes purchase stromectol 3 mg fast delivery, from another animal virus zombie order cheap stromectol on line. Human-to-human spread has been documented vertically from mother to antibiotics for sinus infection dosage order 3mg stromectol overnight delivery neonate, horizontally from colonized humans, and by contaminated blood products. Although Pasteurella species resemble several other organisms morphologically and grow on many culture media at 37°C (98°F), laboratory differentiation is not diffcult. Other effective oral agents include ampicillin, amoxicillin, cefuroxime, cefxime, cefpodoxime, doxycycline, and fuoroquinolones. For patients who are allergic to beta-lactam agents, azithromycin or trimethoprimsulfamethoxazole are alternative choices, but clinical experience with these agents is limited. Doxycycline is effective but should be avoided in children younger than 8 years of age (see Tetracyclines, p 801). Fluoroquinolones are effective but are not recommended for this use in patients younger than 18 years of age (see Fluoroquinolones, p 800). For suspected polymicrobial infection, oral amoxicillin-clavulanate or, for severe infection, intravenous ampicillin-sulbactam, ticarcillin-clavulanate, or piperacillin-tazobactam can be given. The duration of therapy usually is 7 to 10 days for local infections and 10 to 14 days for more severe infections. Antimicrobial therapy should be continued for 4 to 6 weeks for bone and joint infections. Penicillin resistance is rare, but beta-lactamase–producing strains have been recovered, especially from adults with pulmonary disease. Antimicrobial prophylaxis for children with an animal bite wound should be initiated according to the recommendations in Table 2. Adult lice or eggs (nits) are found on the hair and are most readily apparent behind the ears and near the nape of the neck. Excoriations and crusting caused by secondary bacterial infection may occur and often are associated with regional lymphadenopathy. Because hair grows at a rate of approximately 1 cm per month, the duration of infestation can be estimated by the distance of the nit from the scalp. In the United States, infestations are less common in black children than in children of other races. Head lice infestation is not infuenced by hair length or frequency of shampooing or brushing. Head lice are not a health hazard, because they are not responsible for spread of any disease. Head lice only are able to crawl; therefore, transmission occurs mainly by direct head-to-head contact with hair of infested people. Transmission by contact with personal belongings, such as combs, hair brushes, and hats, is uncommon. Away from the scalp, head lice survive less than 2 days at room temperature, and their eggs generally become nonviable within a week and cannot hatch at a lower ambient temperature than that near the scalp. The incubation period from the laying of eggs to hatching of the frst nymph usually is about 8 to 9 days but can vary from 7 to 12 days, being somewhat shorter in hot climates and longer in cold climates. Adult females then may lay eggs (nits), but these will develop only if the female has mated. Wetting hair with water, oil, or a conditioner and using a fne-tooth comb may improve the ability to diagnose infestation and shorten examination time. It is important to differentiate nits from dandruff, benign hair casts (a layer of follicular cells that may slide easily off the hair shaft), plugs of desquamated cells, external hair debris, and fungal infections of the hair. Safety is a major concern with pediculicides, because the infestation itself presents minimal risk to the host. Therapy can be started with over-the-counter 1% permethrin or with a pyrethrin combined with piperonyl butoxide product, both of which have good safety profles. For treatment failures not attributable to improper use of an over-thecounter pediculicide, malathion, benzyl alcohol lotion, or spinosad suspension should be used. No drug truly is ovicidal, but of the available topical agents, only malathion has ovicidal activity. Ideally, retreatment should occur after the eggs that are present at the time of initial treatment have hatched but before any new eggs have been produced. Permethrin is available without a prescription in a 1% lotion that is applied to the scalp and hair for 10 minutes after shampooing with a nonconditioning shampoo and towel drying the hair. Although activity of permethrin can continue for 2 weeks or more after application, some experts advise a second treatment 9 to 10 days after the frst treatment, especially if hair is washed within a week after the frst treatment. Product labeling recommends a second treatment 7 or more days after the frst application if live lice are seen. Pyrethrins are natural extracts from the chrysanthemum and are available (usually formulated with the synergist piperonyl butoxide) without a prescription as shampoos or mousse preparations (both to be applied to dry hair). Pyrethrins have no residual activity, and repeated application 7 to 10 days after the frst application is necessary to kill newly hatched lice. Pyrethrins are contraindicated in people who are allergic to chrysanthemums or ragweed. This organophosphate pesticide that is both pediculicidal and partially ovicidal is available only by prescription as a lotion and is highly effective as formulated in the United States. Malathion lotion is applied to dry hair, left to dry naturally, and then removed 8 to 12 hours later by washing and rinsing the hair. The product should be reapplied 7 to 9 days later only if live lice still are present at that time. The alcohol base of the lotion is fammable; therefore, the lotion or wet hair during treatment should not be exposed to lighted cigarettes, open fames, or electric heat sources, such as hair dryers or curling irons. Malathion is contraindicated in children younger than 2 years of age because of the possibility of increased scalp permeability and absorption. Benzyl alcohol is available by prescription in a lotion formulated with mineral oil and is highly effective as a pediculicide. When applied, suffcient amounts should be used on dry hair to saturate the scalp and entire length of the hair, and then washed off after 10 minutes. Benzyl alcohol use in neonates has been associated with neonatal gasping syndrome, and its use should, therefore, be avoided in this group. Enough of the suspension is used to completely cover dry hair completely, starting with the scalp, and is left on for 10 minutes. Because of the benzyl alcohol, this product should not be used in infants younger than 6 months of age. The lotion is applied to dry hair, starting with the scalp, in an amount suffcient to coat the hair and scalp thoroughly. Ivermectin may be effective against head lice if suffcient concentration is present in the blood at the time a louse feeds. It has been given as a single oral dose of 200 fig/ kg or 400 fig/kg, with a second dose given after 9 to 10 days. Because it blocks essential neural transmission if it crosses the blood-brain barrier and young children may be at higher risk of this adverse drug reaction, currently, ivermectin should not be used in children weighing less than 15 kg (33 pounds). Because of safety concerns and availability of other treatments, lindane shampoo no longer is recommended for treatment of pediculosis capitis. With the products available today and limited data on effectiveness of 1 these other treatments, it is unlikely that any would be used. Data are lacking to determine whether suffocation of lice by application of some occlusive agents, such as petroleum jelly, olive oil, butter, or fat-containing mayonnaise, is as effective as a method of treatment. Because pediculicides kill lice shortly after application, detection of living lice on scalp inspection 24 hours or more after treatment suggests incorrect use of pediculicide, hatching of lice after treatment, reinfestation, or resistance to therapy. In such situations, after excluding incorrect use, immediate retreatment with a different pediculicide followed by a second application 7 to 10 days later is recommended. Itching or mild burning of the scalp caused by infammation of the skin in response to topical therapeutic agents can persist for many days after lice are killed and is not a reason for retreatment. Topical corticosteroid and oral antihistamine agents may be benefcial for relieving these signs and symptoms. Manual removal of nits after successful treatment 1 American Academy of Pediatrics, Committee on School Health and Committee on Infectious Diseases. Removal of nits is tedious and time consuming but may be attempted for aesthetic reasons, to decrease diagnostic confusion, or to improve effcacy.
Zoster occasionally can become disseminated in immunocompromised patients antibiotics vertigo order genuine stromectol online, with lesions appearing outside the primary dermatomes and with visceral complications antibiotics for uti leukocytes cheap stromectol amex. Childhood zoster tends to antimicrobial ointment for burns discount generic stromectol canada be milder than disease in adults and is less frequently associated with postherpetic neuralgia antibiotic impetigo buy 3mg stromectol amex. However, data from immunocompromised children indicate that the risk of developing zoster is lower among vaccine recipients than among children who have experienced natural varicella. Postlicensure data also suggest a lower risk of herpes zoster among healthy vaccinees. Fetal infection after maternal varicella during the frst or early second trimester of pregnancy occasionally results in fetal death or varicella embryopathy, characterized by limb hypoplasia, cutaneous scarring, eye abnormalities, and damage to the central nervous system (congenital varicella syndrome). The incidence of congenital varicella syndrome among infants born to mothers with varicella is approximately 1% to 2% when infection occurs before 20 weeks of gestation. Two cases of congenital varicella syndrome have been reported in infants of women infected after 20 weeks of pregnancy, the latest occurring at 28 weeks. Varicella infection has a higher case-fatality rate in infants when the mother develops varicella from 5 days before to 2 days after delivery, because there is little opportunity for development and transfer of antibody from mother to infant and the infant’s cellular immune system is immature. Humans are infected when the virus comes in contact with the mucosa of the upper respiratory tract or the conjunctiva. In utero infection occurs as a result of transplacental passage of virus during maternal varicella infection. Children who acquire their infection at home (secondary family cases) often have more skin lesions than the index case. Health care-associated transmission is well documented in pediatric units, but transmission is rare in newborn nurseries. In temperate climates in the prevaccine era, varicella was a childhood disease with a marked seasonal distribution, with peak incidence during late winter and early spring. In tropical climates, the epidemiology of varicella is different; acquisition of disease occurs at later ages, resulting in a higher proportion of adults being susceptible to varicella compared with adults in temperate climates. In the prevaccine era, most cases of varicella in the United States occurred in children younger than 10 years of age. The age of peak varicella incidence is shifting from children younger than 10 years of age to children 10 through 14 years of age, although the incidence in this and all age groups is lower than in the prevaccine era. Symptomatic reinfection is uncommon in immunocompetent people; asymptomatic reinfection is more frequent. Since 2007, coverage with 1 dose of varicella vaccine among 19through 35-monthold children in the United States has been 90%. As vaccine coverage increases and the incidence of wild-type varicella decreases, a greater proportion of varicella cases are occurring in immunized people as breakthrough disease. This should not be confused as an increasing rate of breakthrough disease or as evidence of increasing vaccine failure. In the surveillance areas with high vaccine coverage, the rate of varicella disease decreased by approximately 90% from 1995 to 2005 with use of varicella vaccine. Since recommendation of a routine second dose of vaccine in 2006, the incidence of varicella has declined further in children. Immunocompromised people with primary (varicella) or recurrent (herpes zoster) infection are at increased risk of severe disease. Severe varicella and disseminated zoster are more likely to develop in children with congenital T-lymphocyte defects or acquired immunodefciency syndrome than in people with B-lymphocyte abnormalities. Other groups of pediatric patients who may experience more severe or complicated disease include infants, adolescents, patients with chronic cutaneous or pulmonary disorders, and patients receiving systemic corticosteroids, other immunosuppressive therapy, or longterm salicylate therapy. Patients are contagious from 1 to 2 days before onset of the rash until all lesions have crusted. The incubation period usually is 14 to 16 days and occasionally is as short as 10 or as long as 21 days after exposure to rash. Varicella can develop between 2 and 16 days after birth in infants born to mothers with active varicella around the time of delivery; the usual interval from onset of rash in a mother to onset in her neonate is 9 to 15 days. Tzanck Vesicle scraping, swab of lesion Observe multinucleated giant cells with inclusions. Commercial assays generally (IgG) specimens for IgG have low sensitivity to reliably detect vaccineinduced immunity. A signifcant increase in serum varicella IgG antibody between acute and convalescent samples by any standard serologic assay can confrm a diagnosis retrospectively. These antibody tests are reliable for diagnosing natural infection in healthy hosts but may not be reliable in immunocompromised people (see Care of Exposed People, p 779). In immunocompetent hosts, most virus replication has stopped by 72 hours after onset of rash; the duration of replication may be extended in immunocompromised hosts. Oral acyclovir or valacyclovir are not recommended for routine use in otherwise healthy children with varicella. Administration within 24 hours of onset of rash results in only a modest decrease in symptoms. Some experts also recommend use of oral acyclovir or valacyclovir for secondary household cases in which the disease usually is more severe than in the primary case. For recommendations on dosage and duration of therapy, see Antiviral Drugs (p 841). Some experts recommend oral acyclovir or valacyclovir for pregnant women with varicella, especially during the second and third trimesters. Intravenous acyclovir is recommended for the pregnant patient with serious complications of varicella. Intravenous acyclovir therapy is recommended for immunocompromised patients, including patients being treated with chronic corticosteroids. Therapy initiated early in the course of the illness, especially within 24 hours of rash onset, maximizes effcacy. Oral acyclovir should not be used to treat immunocompromised children with varicella because of poor oral bioavailability. In 2008, valacyclovir (20 mg/kg per dose, with a maximum dose of 1000 mg, administered 3 times daily for 5 days) was licensed for treatment of chickenpox in children 2 to <18 years of age. Children with varicella should not receive salicylates or salicylate-containing products, because administration of salicylates to such children increases the risk of Reye syndrome. For immunized patients with breakthrough varicella with only maculopapular lesions, isolation is recommended until no new lesions appear within a 24 hour period; lesions do not have to be completely resolved. Infants with varicella embryopathy do not require isolation if they do not have active lesions. For immunocompetent patients with localized zoster, contact precautions are indicated until all lesions are crusted. Children with uncomplicated chickenpox who have been excluded from school or child care may return when the rash has crusted or, in immunized people without crusts, until no new lesions appear within a 24-hour period. Exclusion of children with zoster whose lesions cannot be covered is based on similar criteria. Lesions that are covered pose little risk to susceptible people, although transmission has been reported. Prophylactic administration of oral acyclovir beginning 2 7 days after exposure also may prevent or attenuate varicella disease in healthy children. There is little information on whether prophylactic oral acyclovir is protective for immunocompromised people. If an inadvertent exposure occurs in the hospital to an infected person by a health care professional, or visitor, the following control measures are recommended: • Health care professionals, patients, and visitors who have been exposed (see Table 3. Types of Exposure to Varicella or Zoster for Which Varicella-Zoster Immune Globulin Is Indicated for People Without Evidence of Immunitya • Household: residing in the same household • Playmate: face-to-face indoor playb • Hospital: Varicella: In same 2to 4-bed room or adjacent beds in a large ward, face-to-face contact b with an infectious staff member or patient, or visit by a person deemed contagious. Zoster: Intimate contact (eg, touching or hugging) with a person deemed contagious. Varicella-Zoster Immune Globulin should be administered as soon as possible and no later than 10 days after exposure. Some experts suggest a contact of 5 or more minutes as constituting signifcant exposure for this purpose; others defne close contact as more than 1 hour. Candidates for Varicella-Zoster Immune Globulin, Provided Signifcant Exposure Has Occurreda • Immunocompromised children without evidence of immunityb c • Pregnant women without evidence of immunityd • Newborn infant whose mother had onset of chickenpox within 5 days before delivery or within 48 h after delivery • Hospitalized preterm infant (28 wk or more of gestation) whose mother lacks evidence of immunity against varicella • Hospitalized preterm infants (less than 28 wk of gestation or birth weight 1000 g or less), regardless of maternal immunity a See text and Table 3. Administration of varicella vaccine to people without evidence of immunity 12 months of age or older, including adults, as soon as possible within 72 hours and possibly up to 120 hours after varicella exposure may prevent or modify disease and should be considered in these circumstances if there are no contraindications to vaccine use. A second dose should be given at the age-appropriate interval after the frst dose. Physicians should advise parents and their children that the vaccine may not protect against disease in all cases, because some children may have been exposed at the same time as the index case.
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