CONTINUING EDUCATION

Published through an educational grant from WYETH-AYERST LABORATORIES
TRENDS IN PHARMACY AND PHARMACEUTICAL CARE

An ongoing CE program of The University of Mississippi School of Pharmacy and DRUG TOPICS

The University of Mississippi School of Pharmacy is approved by the American Council on Pharmaceutical Education as a provider of continuing pharmaceutical education. Accredited in every state requiring CE. ® ACPE # 032-999-01-015-H01

This lesson is no longer valid for CE credit after 12/31/03.

CREDIT:

This lesson provides two hours of CE credit and requires a passing grade of 70%.

OBJECTIVES:

Upon completion of this article, the pharmacist should be able to:

• Describe the life cycle of the head louse
• Discuss methods for diagnosing pediculosis
• Differentiate among nonpharmacologic and pharmacologic treatments of head lice
• Counsel patients on the appropriate use of lice medications, with emphasis on prevention

GOAL:

To provide pharmacists with a review of current pharmacologic and nonpharmacologic treatments of head lice

Counseling patients and families about head lice

By T. Kristopher Harrell, Pharm.D. Assistant Professor of Pharmacy Practice University of Mississippi School of Pharmacy, Jackson Kristi W. Kelley, Pharm.D. Primary Care Resident, University of Mississippi Medical Center, Jackson Deborah S. King, Pharm.D. Assistant Professor of Pharmacy Practice, Division of Hypertension University of Mississippi Medical Center, Jackson

Head lice is the most prevalent parasitic infestation of human beings in the United States and Europe and affects as many as six million to 12 million children and adults worldwide each year. Approximately $367 million is spent in the United States on over-the-counter (OTC) pediculicides and associated products/services accrued by school systems annually.

In developed societies, social stigma and embarrassment often occur with lice infestation—usually because of the misconception that it is associated with being unclean. Unfortunately, these reactions may also occur in professionals who are treating the infestations.

In other parts of the world, such intense reactions are not evoked by lice infestations, and in many cases infestations are considered normal. It is important for pharmacists to understand the diagnosis and treatment of lice infestations in order to dismiss myths about treating head lice and help direct appropriate patient care.

The human head louse, Pediculus humanus capitis, is an external parasite that infests only humans. Since lice have an obligatory blood-feeding habit, they are required to feed on human blood several times a day. They are most frequently found on or close to the scalp so they can maintain sufficient body temperature; however, they have also been found on the eyebrows of certain infected individuals.

Life cycle

The life cycle of the head louse includes three stages—egg, nymph, and adult. The eggs are known as nits. Because the nits are difficult to see, they may be confused with dandruff, droplets of hair spray, or other insects. Adult females lay the nits. The nits are deposited and cemented at the base of the hair shaft within 6 mm of the scalp by a glue-like glandular discharge secreted by the female louse. Nits are usually oval, yellow, or white in color, and 0.8 mm by 0.3 mm in size. Nits usually hatch in six to nine days.

When the nit, or egg, hatches, a nymph is released. After hatching, the nit shell becomes a more visible dull yellow but remains attached to the hair shaft. As a juvenile louse, the nymph has the appearance of an adult head louse; however, it is smaller—about the size of the pinhead. Nymphs begin feeding shortly after they emerge from nits and undergo three molts, which take three to five days each. Within nine to 15 days of hatching, adult lice appear and begin laying eggs. An adult louse is approximately 1/16 to 1/8 in. long—about the size of a sesame seed. It has six legs with claws, is tan to grayish-white in color, though in infected persons with darker-colored hair the louse may appear darker. Adult lice may live up to 30 days if they get the necessary blood from their host several times a day. Without these feedings, the lice will die within one to two days.

Diagnosis

Infestation of head lice is diagnosed when live nymphs or adult lice are identified on the scalp. An active manifestation is suggested when numerous nits are found within 6 mm of the scalp. Previous infestation is suggested when nits are found farther than 6 mm from the scalp. Generally, an infested person has fewer than a dozen active lice on the scalp at any time but may have hundreds of viable, dead, and hatched eggs. Untrained eyes may identify nits that are hatched and empty shells as viable eggs. To confirm the diagnosis, it may be necessary to capture the lice using a strip of clear tape for viewing under a microscope.

The accuracy of the diagnosis of head lice has been questioned. A recent study by Richard Pollack, et al., examined the accuracy of the diagnosis of head lice and the implications for treatment of head lice in North America. Samples harvested by both healthcare professionals and the general public were sent to a reference center for diagnosis of pediculosis.

The authors of the study concluded that parents and school personnel more accurately diagnosed head lice infestations than did physicians; both groups were poor at distinguishing active from inactive infestations. The study also demonstrated that patients with chronic infestations were diagnosed inaccurately with the same consistency as patients with recent head lice infestations.

Symptoms

Many cases of head lice infestation are asymptomatic. Symptoms that may be noted include itching, a tickling feeling in the hair, and scalp irritation. Complications rarely develop, but they may include secondary bacterial infections. Itching, considered the primary symptom associated with infestation, is thought to occur as a result of an allergic reaction to the louse saliva, which is injected into the scalp during feeding. The allergic reaction of the patient to the saliva is an immune response reaction that progresses from no response, to delayed and immediate reactions, to tolerance. Because this is a hypersensitivity reaction, the itching may take as long as three months to develop.

For many, itching is the initial reason to suspect an infestation. In developed countries, it has also been noted that head lice may be one of the most common causes of impetigo of the scalp and may be the only cause of pyoderma (bacterial skin infection) of the scalp. In cases of severe lice infections, which have persisted for 12 to 18 months, secondary sensitization may develop, causing a general systemic reaction in which the patient experiences a feeling of malaise and generalized fatigue.

Epidemiology

Children between the ages of four and 11, preschoolers, and elementary-aged children have the highest prevalence of head lice infection. Because girls have a tendency to play in small groups with close head-to-head contact more often than boys, they tend to have a higher incidence of infection. Any changes in infestation patterns do not appear to be seasonal but rather are based on social and behavioral changes. In the United States, African Americans are rarely infested with head lice. The American louse is believed to prefer the shape and width of the hair shaft of other races.

Transmission

Despite the ready transmission of head lice, the potential for an epidemic to develop is minimal. Head lice are transferred mainly by direct head-to-head contact with an infested individual. It is estimated that it takes at least 30 seconds for lice to move from one head to another; therefore, transient contact is insufficient for lice to be transferred between heads. Places where head lice may be transmitted include school (especially during recreational activities), slumber parties, sports activities, camps, and playgrounds.

The other method of head lice transmission is via fomite transmission, which occurs when people share infested clothing, such as hats, scarves, coats, sports uniforms, or hair accessories; use infested combs, brushes, or towels; or lie on a bed, couch, pillow, carpet, or stuffed animal that has recently been in contact with an infested person.

Social implications

In developed societies, parents may react to the knowledge that their children have head lice with shock and revulsion, commonly believing that head lice are associated with people of poor personal hygiene. Lice infestations are, however, found equally on individuals with clean hair as on those with dirty hair. Because of the misconceptions and stigma associated with the diagnosis of lice, it can be difficult to trace contacts.

Parents often do not want to admit to other members of their family and to friends that their children have lice. After diagnosis of an infestation, parents should not spend time trying to place blame but should focus on educating other parents and children about the treatment of head lice.

Schools and day care centers

It is now believed that head lice infestations are spread from the community into the schools, since it is known that school-aged children, in particular elementary school children, are the group most likely to contract lice. Parents can help protect children against lice infestations by helping them understand that personal items should not be shared with classmates. Schools and day care centers can help prevent transmission of lice via clothing, such as coats, by storing them separately from items such as sleeping mats and toys.

It is important for parents, school administrators, and healthcare professionals to work together to formulate rational approaches to dealing with reports of lice among students. Parents and teachers should observe children for constant scratching of the scalp. Parents or teachers should examine the scalp, hair, and nape of the neck of these children for the presence of lice or nits on a regular basis. While school nurses can be helpful in identifying infestations, they often lack the expertise and equipment to distinguish active from inactive infestations.

Parents and school personnel should cautiously use mass screenings to identify infested children and ensure treatment, because they may not be qualified to appropriately identify infested patients. If parents or teachers cannot determine if a child is infested, a healthcare professional should be consulted.

Some healthcare professionals believe that children in whom lice or nits are discovered should not necessarily be sent home or isolated. When identifying these patients, it should be remembered that treatment is indicated only in persons who have active infestations.

It should be remembered that only about a dozen live lice are on the head at any one time. The eggs are attached to the base of the hair shaft and move away from the base as the hair grows. Eggs that are more than one-half inch from the scalp are usually hatched. This alone does not indicate an active infestation.

The 'No Nit' policy

The National Pediculosis Association (NPA) endorses the No Nit policy as the public health standard intended to keep children lice-free, nit-free, and in school. The No Nit policy encourages community education to help parents understand the need for such a policy and to outline what they need to do to carry it out.

The No Nit policy also recommends the exclusion of a child from school, camp, or any other child care setting until all head lice, lice eggs (nits), and egg cases have been removed. The goal of the No Nit policy is to decrease the transmission of lice by keeping infested children out of school and other public group settings.

Opponents to the No Nit policy believe its enforcement can lead to inappropriate exclusion of children with residual nits, who may have previously been treated. Other opponents believe the policy is counterproductive and does not appear to affect the prevalence of head lice; they argue that simply having nits does not warrant a child's exclusion from school. However, proponents of the No Nit policy suggest that few of those who oppose the policy would accept infestations for themselves or for their own children.

Another concern of the opponents of the No Nit policy is excluding infested children from school until they have been treated or until they have been rendered free of all nit-like objects. Under the No Nit policy, children that are repeated failures may have extended absences due to school-enforced exclusion. In some instances, schools have taken legal action against parents of such children, charging the parents with neglect or abuse.

Proponents of the No Nit policy say that the policy is beneficial because it encourages families to do their part by performing routine screenings. This also allows for early detection, hopefully accurate identification, and removal of lice and nits. The policy helps establish guidelines for dealing with lice infestations as well as helping to educate the public about appropriate procedures prior to actual outbreaks. Since the NPA supports the No Nit policy, it provides tips on how to make the policy succeed. It promotes strategies that include proactive community education, routine screening and early detection, manual removal of all lice and nits, and temporary dismissal of children with head lice and/or nits.

Treatment goals

Treating lice infestations is a multifaceted approach. Treatment includes use of pediculicides along with combing to prevent spreading infestation as well as to prevent reinfestation. Recommendations on steps for treatment are outlined by several national organizations including the Centers for Disease Control & Prevention (CDC), the National Pediculosis Association, and the Harvard School of Public Health. Table 1 lists recommended Web sites for the various organizations.

Treatment

Many experts agree that patients should be identified as having a lice infestation—live lice and unhatched eggs—before treatment is initiated. (See Table 2 on tips for pharmacists.) It is easiest to look for head lice with the assistance of a magnifying glass, a strong light, and a fine-toothed comb when the hair is wet. Once a louse has been captured using clear tape, treatment can begin. Treatment should include a pediculicidal agent, mechanical removal, and, potentially, environmental measures. Since infestations have usually existed for several weeks prior to their discovery, contacts over the prior month should be traced, if possible. The contacts should also be treated, if needed. Treating contacts not only helps reduce the risk of reinfestation to the individual but also helps reduce the spread of lice throughout the community.

Nonpharmacologic remedies

Use of conditioners before applying a pediculicide should be avoided, since the conditioners coat the hair and may protect the lice. In an effort to kill lice and nits in households, the CDC makes recommendations for treating households of an infested person (see Table 3). The recommendations include using the hot water cycle (130° F) of a washing machine to clean all washable clothing and bed linens touched by the infested person two days prior to treatment. Washable items should then be dried using the hot cycle of the clothes dryer for at least 20 minutes. Items that cannot be washed should be dry- cleaned. Items that cannot be washed or dry-cleaned, such as stuffed animals or comforters, should be sealed and stored in a plastic bag for two weeks. The CDC also recommends vacuuming the floor and furniture of the infested individual's household instead of using fumigant sprays, which can be toxic. Combs and brushes that have been used by infested individuals should be soaked in rubbing alcohol or a disinfectant, or washed in hot, soapy water.

Even if the recommended measures for clearing the household of infestation are implemented, household contacts' scalp, hair, and neck should still be inspected for lice and nits every two to three days. Household members should be treated only if lice or nits are found. Prophylactic treatment is not recommended. If children less than two years of age are infested, they should be treated by mechanical removal of lice and nits rather than by use of a pediculicide.

Heat

Heat, as applied by hand-held hair dryers, may produce enough hot, dry air to kill lice and nits. However, caution should be exercised if hair dryers are used in this setting, since the hot air can scald the scalp and hair. Objective treatment information is not available on the treatment time, temperature, and distance from the hair dryer. Although other heated hair devices, such as curling irons or straighteners, may kill some lice and nits, these devices cannot be safely used close to the scalp, where viable eggs are most abundant. A clothes dryer set on high heat or a hot iron can be used to successfully kill lice or nits on clothing or items such as pillowcases, sheets, and towels. Hair accessories, brushes, combs, and hats should be washed in hot water each day to dislodge any lice or nits.

Freezing

Freezing temperatures can kill lice and nits on objects. Inanimate objects that cannot be heated in a clothes dryer may be placed in a freezer or outdoors if temperatures are cold enough. Although this treatment may be effective, it usually takes several days to kill the lice and nits.

Combing

Prior to pharmacologic therapy, mechanical removal (including combing, picking out lice by hand, or shaving the head) was the traditional way louse control was achieved. Mechanical removal is still considered an effective method of treatment (see Table 4). Effective mechanical removal should include the use of light, magnification, and a louse or nit comb to assist in the location and removal of lice. By combing each day, live lice, including those that have hatched since the previous day, can be eliminated. Combing should continue daily for about two weeks, until no live lice are discovered.

Louse combs can be helpful in removing lice and nits. Fine-toothed combs may be included with packages of pediculicides or may be purchased separately. Characteristics that can determine the effectiveness of the louse combs include: construction—length and spacing of comb teeth; composition—metal vs. plastic; texture of the infested individual's hair—straight hair vs. tight curls; technique used to comb; and time and care expended in the effort.

There are tips to make the combing process an effective part of dealing with a lice infestation. Before combing, the hair should be clean and well combed or brushed. The wet hair should be divided into small sections. Combing from the scalp outward is usually recommended; however, back-combing may also help to dislodge eggs and nits. The comb should be cleaned frequently during the combing process to remove lice or nits that have been entrapped. For the lice and nits to be completely removed, combing may take several hours each night. Since this is the preferred method for lice removal in young children, it is helpful for parents to have the child watch television or a video during combing. This process should be repeated on successive nights until no active lice are noted. When used in conjunction with topical agents, combing should be done at least every two nights.

Electronic louse combs are now available (e.g., Robi Comb). They resemble small bug zappers and have oscillating teeth. Opponents of the electric comb believe that they offer no advantages over a well-designed traditional louse comb and argue that the teeth of the electric combs may not even reach the scalp, thus failing to remove active lice or eggs.

Pharmacologic remedies

Topical agents that are used to treat lice infestations are known as pediculicides. These agents are lousicidal, meaning the agents are toxic to the nymphs and adult lice. However, these agents vary in their ovicidal characteristics. Their potential to cause toxicity to the developing embryo is less clear, because the embryo lacks a central nervous system during its first four days of existence. Whether supposed residual effects make the agents ovicidal or if these effects are attributable to the development of resistance is debatable.

Products containing pyrethrins or the synthetic pyrethroid permethrin are available over the counter. They are considered first-line agents because they are generally free of major toxicities.

The extracts of the flower of the pyrethrum plant, Chrysanthemum cincerariaefolium, is the source for natural pyrethrins. Pyrethrins excessively stimulate the nervous systems of lice, thus killing them. Piperonyl butoxide, a metabolic inhibitor of cytochrome P450, enhances pyrethrin's activity by delaying its metabolism by the louse. (Table 5 includes examples of combination products.) Pyrethrin products do not have reliable ovicidal effects; therefore, individuals infested with head lice should be treated again in seven to 10 days to target any lice that hatched after the first treatment.

Synthetic pyrethrins, which are also called pyrethroids, include permethrin products, permethrin 1% (e.g., Nix Creme Rinse). Pyrethroids kill head lice by keeping sodium channels open an unusually long period of time, which prolongs the depolarization afterpotential, thus leading to hyperexcitatory symptoms caused by membrane depolarization, repetitive discharges, and synaptic disturbances. Pyrethoids also have a knockdown effect, which is a fast-acting effect that immobilizes insects upon exposure, often preceding a lethal action, resulting from peripheral and central effects on the nervous system. Per-methrin does not usually require retreatment, because the product remains active for two weeks.

There are reports of applying prescription-strength permethrin 5% cream and leaving it on overnight under a shower cap for resistant cases. However, there have been reports by Richard Pollack, et al., that some head lice in the United States that were resistant to permethrin did not respond to higher doses of it. It is their opinion that using higher concentrations of permethrin is not likely to be effective in resistant cases. They also state that pyrethrin would be ineffective in killing permethrin-resistant lice, since the two pediculicides have similar mechanisms of action.

Malathion and lindane are two prescription products that are also commonly used to treat lice infestations if treatment with pyrethrin products fail or if patients are allergic to ragweed or chrysanthemums.

Malathion is an organophosphate insecticide that is commonly used to kill other pests (centipedes, crickets, fleas, houseflies, wasps, moths, for example). The Food & Drug Administration reapproved it in 1999 after it was taken off the market for inadequate sales, foul odor, and long application time. Malathion works by irreversibly inhibiting cholinesterase; therefore, if systemically absorbed, it may cause excessive cholinergic activity. It is available as a lotion for topical use only.

Lindane is a chlorinated hydrocarbon pesticide that was once the most common treatment of lice. It destroys lice by excessively stimulating their central nervous systems, thus having lousicidal effects but only limited ovicidal effects. Lindane may be systemically absorbed; seizures, and, in rare cases, deaths, have been reported. These serious adverse events have primarily occurred after misuse, abuse, and accidental or intentional ingestion of the product, and many European countries have banned the use of lindane in humans. Most recently, in the United States, the state of California has banned lindane for therapeutic use, making it illegal to use or sell lindane after Jan. 1, 2002. Similar legislation is being considered in other states.

Although both prescription and OTC agents are able to provide pediculicide effects, their ovicidal effects cannot be guaranteed. Therefore, combing is an essential component of any pediculicide treatment to ensure removal of eggs and nits, because pediculicides do not remove them from the hair.

Alternative treatments

Two oral agents, Ivermectin and sulfamethoxazole/trimethoprim, have also been used in the treatment of lice infestations. Ivermectin is an antiparasitic agent that is effective against certain nematodes. It paralyzes these organisms and is thought to have the same effect on lice. Only brief reports and small open-label studies have been conducted with ivermectin, and its effectiveness has not been clearly established. Sulfamethoxazole/trimethoprim has also been used; it seems to kill symbiotic bacteria in the louse gut, ultimately destroying the lice. However, the potential for promoting bacterial resistance has limited its use.

Natural remedies

Numerous products (e.g., Not Nice to Lice Shampoo, Lice Be Gone Shampoo, Clear Lice Egg Remover, RID Lice Egg Loosener Gel, Schooltime Shampoo, LiceGuard Shampoo, HairClean 1-2-3 Lice Remover) are being promoted as natural treatment of lice infestation. Most of these products do not contain pediculicides and should be used only in conjunction with pyrethrin- or permethrin-containing products.

Other alternative products are not ovicidal or pediculicidal, and their success can usually be attributed to parents being meticulous and motivated in caring for their children, rather than to the methods themselves.

A popular alternative is the use of food-grade oils or hair gels that are believed to immobilize and suffocate lice on the scalp. Although the success of such agents has been reported, an equal number of treatment failures with these alternative agents have also been reported. Oils, like any hair conditioner, lubricate the hair, which eases efforts to pass lice and nit combs through the hair. Although food-grade oils such as olive oil seem safe, they can be harmful because they are difficult to remove from the scalp and hair. There are no published clinical trials evaluating the efficacy of olive oil.

Materials such as motor or machine oil should be avoided, since they are potentially harmful. Severe burns have occurred in children as a result of using highly flammable products such as gasoline and kerosene. Since the evidence is not available to support the use of oil substances, these products should not be recommended as a treatment for head lice.

Combing is an integral part of using pediculicide treatments to remove viable nits that may not be killed if the agents do not also have ovicidal power. Using a 1:1 mixture of vinegar and water to wet the hair may help loosen the nits and allow for easier removal. Removal of viable nits is one way to prevent reinfestation.

Liberally applying mayonnaise, petroleum jelly (Vaseline), or lard to the head of an infested individual, placing a shower cap on the head, and leaving the substance on overnight has been reported to be effective. The thought is that these products, like other oil-based products, will smother the lice. However, even if the oil-based products smother the lice, combing is needed to remove nits and prevent reinfestation.

Petroleum jelly creates a new problem when it is used to kill lice, because removing the petroleum jelly from hair is cumbersome and may take up to one week to remove by shampooing. Unfortunately, to remove the petroleum jelly, parents may use powders that frequently contain talc, which should never be used around a child's face. Mayonnaise is also difficult to remove from hair and could be contaminated with bacteria, since it is made with eggs. None of these products have been tested in efficacy trials; therefore, they cannot be considered safe or effective treatments.

Tea tree oil is promoted as a fungicide and bactericide, which means it should be used carefully. Unfortunately, parents are not diluting the concentrated form, so children are being overexposed to tea tree oil. It is not known whether tea tree oil kills lice, but it is thought to harm the scalp, thus creating the potential for other problems to develop.

The recommendation to wrap the infested individual's head in plastic and apply heat with a hair dryer is another erroneous attempt to remove lice and nits. The use of plastic products and shower caps along with pesticidals is dangerous, because the plastic can act as an occlusive dressing for chemical concoctions that were never intended for use in this manner.

Shaving a child's head to rid the hair of lice is traumatic. Although a shaved head may be acceptable for young boys, it is not warranted and therefore not recommended for most children.

Resistance

There have been multiple reports of head lice resistance worldwide. However, little is known regarding the actual occurrence of resistance or whether the incidence is increasing. The most important factor in effective treatment of head lice infestation is ensuring that the infestation is thoroughly treated and eliminated to prevent reinfestation. While further infestation is not indicative of resistance, it can lead to retreatment, which can indirectly cause resistance. Such continued exposure can cause potentially toxic effects to the patient. Therefore, it is imperative that patients receive adequate and correct information in order to most effectively eradicate head lice and prevent reinfestation.

References available upon request

TEST QUESTIONS

Write your answers on the answer form appearing below (photocopies of the answer form are acceptable) or on a separate sheet of paper. Mark only one correct answer.

1. Lice infestation is the most prevalent human parasitic infection in which areas of the world?

a. India and South Africa
b. China and Japan
c. United States and Europe
d. Mexico and South America

2. The human head louse is an external parasite known as which one of the following?

a. Pediculus humanus capitis
b. Pthirus pubis
c. Pediculus corporis
d. Pthirus capitis

3. The life cycle of the louse includes which three stages?

a. Egg, nymph, and adult
b. Embryo, nivea, and adult
c. Egg, larva, and adult
d. Embryo, larva, and adult

4. The adult louse is about the size of which one of the following?

a. Sunflower seed
b. Corn kernel
c. Sesame seed
d. Pinhead

5. Active manifestation of lice is suggested where?

a. Farther than 6 mm from the scalp
b. Less than 6 mm from the scalp
c. Farther than 12 mm from the scalp
d. Less than 12 mm from the scalp

6. The primary symptom of lice infestation is which one of the following?

a. Pain
b. Itching
c. Inflammation
d. Infection

7. Which one of the following is most likely to contract head lice?

a. A 13 year old girl
b. A 13-year old boy
c. A five-year old girl
d. A five-year old boy

8. Lice can be transmitted via which means?

a. Animal to human and fomite to human
b. Human to human and fomite to human
c. Animal to fomite and fomite to human
d. Human to human and animal to human

9. Lice infestations are most likely to occur in which one of the following instances?

a. Just as often in dirty hair as clean hair
b. More often in dirty hair
c. More often in clean hair
d. More often in African Americans

10. Which one of the following organizations has developed a "No Nit" policy?

a. The National Lice Association
b. The National Pediculosis Association
c. The National Entomology Network
d. The No Nit Network Organization

11. Which one of the following is not a CDC recommendation for nonpharmacologic measures used to treat head lice?

a. Wash clothes in lukewarm water for at least 20 minutes.
b. Dry clothes using the hot cycle for at least 20 minutes.
c. Vacuum floor and furniture instead of using fumigant sprays.
d. Soak combs and brushes in rubbing alcohol and disinfectants.

12. Which one of the following is not an adequate nonpharmacologic means of eradicating lice?

a. Heating
b. Freezing
c. Combing
d. Wetting

13. Pyrethrin-containing products are developed from the extract of which flower?

a. Carnation
b. Chrysanthemum
c. Daisy
d. Geranium

14. Pharmacologic treatment options for lice infestation include all of the following except:

a. Permethrin
b. Pyrethrin
c. Malathion
d. Bacitracin

15. Which of the following agents does not usually require retreatment because the product remains active for two weeks?

a. Permethrin
b. Pyrethrin
c. Lindane
d. Malathion

16. Which of the following agents is available as a lotion only?

a. Malathion
b. Lindane
c. Ivermectin
d. Permethrin

17. Which one of the following is a potential side effect of lindane that has been reported with systemic absorption?

a. Liver-enzyme elevation
b. Seizures
c. Dental caries
d. Renal failure

18. The use of sulfamethoxazole/trimethoprim has been limited due to which one of the following?

a. Increased side effects
b. Strong odor
c. Ineffectiveness in children
d. Potential for increased bacterial resistance

19. Which one of the following "natural therapies" may help loosen nits without adverse effects?

a. Application of motor or machine oil
b. Application of mayonnaise
c. Application of diluted vinegar
d. Application of olive oil

20. The most important measure in preventing resistance of head lice is which one of the following?

a. Ensuring that the infestation is thoroughly treated and eliminated
b. Using multiple products simultaneously to avoid cross-resistance
c. Repeating products after 10 days even if lice are absent after initial treatment
d. Using products only if nits are present on the entire scalp

Click here to view full-size graphic