Molluscum Contagiosum
Molluscum contagiosum is caused by up to four closely-related types of pox virus, MCV-1 to MCV-4 and their variants [1, 2]. In small children, virtually all infections are caused by MCV-1. In all forms of infection, the individual lesions are relatively similar, smooth-surfaced, firm, dome-shaped, pearly papules averaging 3-5 mm in diameter. Some giant lesions may be up to 1.5 cm in diameter. A central umbilication is characteristic. The clinical pattern depends on the risk group affected.
Molluscum contagiosum occurs worldwide but is more prevalent in tropical areas [3]. The infection is most common in children, sexually active adults, and persons with impaired cellular immunity, particularly HIV-positive patients.
In children, single-site involvement is relatively more common than multiple-site involvement. The most common sites affected are the head and neck, followed by trunk, upper extremity, genitalia, and lower extremity. . In adults, multiple-site involvement is more common than single-site involvement, and the most common sites are the head and neck, followed by trunk, upper extremity, genitalia, and lower extremity.
Molluscum contagiosum is a common cutaneous viral infection, but its incidence in most areas of the world is not reliably known [4]. The disease is much less common under the age of 1 year, perhaps because of transmission of maternal immunity and because of the long incubation period [5]. Epidemiological data support the notion that molluscum contagiosum is primarily a disorder of children, with a peak incidence at age 10-12 years [8, 9]. In a study done in Alaska, molluscum developed in 35 percent of exposed family members [12].
Although molluscum contagiosum is chiefly a disease of children, the incidence in adults is rising, probably as a result of sexual transmission. [9] The National Disease and Therapeutic Index survey found that the greatest number of cases occur among patients aged 20-29, although affected women are younger than affected men [12]. Their analysis is limited to molluscum contagiosum diagnosed in patients 15 years or older.
Molluscum contagiosum is usually asymptomatic; a minority of patients complain of itching or tenderness [9]. Lesions are usually more widespread in children than in adults and, although adults with genital disease rarely develop extra genital lesions, 10-50 percent of infected children have lesions in the genital area [17]. The involvement of the genitalia occurs in as a part of multiple site involvement, and in no way implies a history of sexual abuse of these children in and of itself.
Previous reports on molluscum contagiosum in healthy adults describe a distribution of lesions involving the genital area, lower abdomen, and upper thigh [9, 18]. Molluscum contagiosum lesions generally begin as tiny papules that grow over several weeks to a diameter of 3-5 mm, occasionally enlarging to 10-15 mm, producing giant molluscum [17]. The number of lesions is usually fewer than 30 in immunocompetent hosts, but as many as several hundred may be seen [9]. The size is less than 10 mm in about 98% of children and 84% of adults. In children, about 84% of the cases have fewer than 20 lesions; whereas, in the adults, 69% of the cases have fewer than 20 lesions.
References
1. Nakamura J, Muraki Y, Yamada M, Hatano Y, Nii S. Analysis of molluscum contagiosum virus genomes isolated in Japan. J Med Virol. 1995 Aug;46(4):339-48. PubMed
2. Odom RB, James WD, Berger TG. Andrews' Diseases of the Skin-Clinical Dermatology, 9th edn. Philadelphia: WB Saunders Company 2000; 501-503.
3. Diven DG. An overview of poxviruses. J Am Acad Dermatol. 2001 Jan;44(1):1-16. PubMed
4. Sterling JC, Kurtz JB. Viral infections. In: Champion RH, Burton JL, Burns DA, Breathnach SM, eds. Rook/Wilkinson/Ebling Textbook of Dermatology, Vol. 2, 6th edn. Oxford: Blackwell Science Ltd, 1998: 995-1095.
5. Postlethwaite R, Watt JA, Hawley TG, Simpson T, Adam H. Features of molluscum contagiosum in the north-east of Scotland and in Fijian village settlements. J Hyg (Lond). 1967 Sep;65(3):281-91. PubMed
6. Torfs M, Lambelin G. Considérations sur le Molluscum Contagiosum en milieu tropical. Ann Soc Belg Med Trop 1959; 39: 703-709. PubMed
7. Sturt RJ, Muller HK, Francis GD. Molluscum contagiosum in villages of the West Sepik District of New Guinea. Med J Aust. 1971 Oct 9;2(15):751-4. PubMed
8. Postlethwaite R. Molluscum contagiosum. Arch Environ Health. 1970 Sep;21(3):432-52. PubMed
9. Gottlieb SL, Myskowksi PL. Molluscum contagiosum. Int J Dermatol. 1994 Jul;33(7):453-61. PubMed
10. Sharma RC, Mendiratta V. Clinical profile and of cutaneous infections and infestations in the paediatric age group. Indian J Dermatol 1999; 44: 174-178.
11. Ghosh SK, Saha DK, Roy AK. A Clinico-aetiological study of dermatoses in the paediatric age group. Indian J Dermatol. 1995; 40; 29-31.
12. Overfield TM, Brody JA. An epidemiologic study of molluscum contagiosum in Anchorage, Alaska. J Pediatr. 1966 Oct;69(4):640-2. PubMed
13. Becker TM, Blount JH, Douglas J, Judson FN. Trends in molluscum contagiosum in the United States, 1966-1983. Sex Transm Dis. 1986 Apr-Jun;13(2):88-92. PubMed
14. Sexually transmitted diseases. Extract from the annual report of the Chief Medical Officer of the Department of Health and Social Security of the year 1980. Br J Vener Dis. 1983 Apr;59(2):134-7. PubMed
15. Curtin BJ, Theodure FH. Ocular molluscum contagiosum. Am J Ophthalmol. 1955; 39: 302-307. PubMed
16. Low RC. Molluscum contagiosum. Edinburgh Med J 1943; 53: 657.
17. Douglas JM Jr. Molluscum contagiosum. In: Holmes KK, Mardh P-A, Sparling PF, Stamm WE, Lemon SM, Wasserheit JN, Piot P, eds. Sexually Transmitted Diseases, 3rd edn. New York: McGraw-Hill 1999:385-389.
18. Lynch PJ, Minkin W. Molluscum contagiosum of the adult. Probable venereal transmission. Arch Dermatol 1966; 98: 141-143. PubMed
19. Thappa DM, Karthikeyan K, Manjunath JV. Giant molluscum contagiosum. Indian J Dermatol 2002; 47:167-168.
20. Liahey AB, Shane JJ, Listhaus A, Trachtman M. Molluscum contagiosum eyelid lesions as the initial manifestation of acquired immunodeficiency syndrome. Am J Ophthalmol 1997; 124: 240-241. PubMed
21. Smith KJ, Skelton H. Molluscum contagiosum: recent advances in pathogenic mechanisms and new therapies. Am J Clin Dermatol 2002; 3: 535-545. PubMed
22. Czelusta A, Yen-Moore A, Van der Straten M, Carrasco D, Tyring SK. An overview of sexually transmitted diseases. Part III. Sexually transmitted diseases in HIV-infected patients. J Am Acad Dermatol 2000; 43:409-432. PubMed.
The above information is excerpted from Dermatology Online Journal vol 9 #5 2003
"Clinical profile of molluscum contagiosum in children versus adults" by Chandrashekar Laxmisha, Devinder M Thappa, and Telanseri J Jaisankar
Department of Dermatology and STD, JIPMER, Pondicherry, India. dmthappa@vsnl.net; dmthappa@jipmer.edu
Molluscum contagiosum is caused by a virus that is a member of the poxvirus family. Poxviruses are notorious for their ability to evade the host's immune system by both acitve and passive mechanisms. Since the eradication of smallpox, the only poxvirus that naturally infects humans is molluscum contagiosum virus (MCV). MCV causes benign proliferative lesions of the skin in normal individuals. There are at least two types of MCV based on DNA restriction analysis. There does not appear to be any predilection for one virus type to infect certain groups of people, certain ages, or certain body areas. Both viruses seem to infect equally. A recent study demonstrated that one of the proteins coded by the MCV genome inhibits the body's lymphocytes and prevents inflammation. This is apparantly why it takes so long for the body to rid itself of MCV.
This is a common infection in children. It is frequently seen on the face, neck, arm pit, arms, and hands but may occur anywhere on the body except the palms and soles.Molluscum contagiosum (MCV) is a common infection throughout the United States. It accounts for approximately 1% of all diagnoses of skin disorders. The exact incidence in the United States is unknown. Higher incidence in children with eczema as well as in immunocompromised individuals has been documented. An Australian study found anti-MCV antibodies in 39% of adults older than 50 years, demonstrating exposure to be very common.There is no well-documented predilection for infection among any racial group. Studies do not demonstrate any definite difference in incidence between the sexes. Cell-mediated immunity is thought to be important in modulating and controlling the infection.
The virus is contagious through direct contact, as seen in children, but may spread by sexual contact. Molluscum is generally seen on the genitals as a sexually-transmitted disease. Early lesions on the genitalia may be mistaken for herpes or warts but, unlike herpes, these lesions are painless. Because molluscum produces no serious illness and is not of long-term public health significance, it has not been treated as other sexually-transmitted diseases. The importance is significant in the growing population of immunocompromised people with AIDS, who may have rapidly worse case of molluscum contagiosum.
Typically, the lesion of molluscum begins as a small papule which may become raised up to a pearly, flesh-colored nodule. The papule often has a dimple in the center (umbilication). These papules may occur in lines, where the person has scratched. Scratching or other irritation causes the virus to spread in a line or in groups (crops).
The papules are approximately 2 - 5 millimeters in diameter and painless. There is usually no inflammation and subsequently no redness unless the person has been digging or scratching at the lesions. In the mature molluscum, the top of the nodule may be opened with a sterile needle and a small waxy core can be seen and squeezed out of the lesion.
Molluscum contagiosum is a chronic infection and lesions may persist from a few months to a few years. These lesions ultimately disappear without scarring. (Unless there is excessive scratching, which may leave marks.)
Symptoms Return to top
The skin lesion commonly has the following qualities:
* Small (2 - 5 millimeter diameter)
* Dimple in center
* Initially firm, flesh-colored, pearl-like, dome-shaped
* Later lesions become softer, gray, and may drain
* Central core or plug of white, cheesy or waxy material
* Painless
* Single or multiple (usually multiple)
* Common locations in children: face, trunk, limbs
* Common locations in adults: genitals, abdomen, inner thigh
Figure 1: Typical appearance of molluscum on the abdomen of a 7 year old girl. Copyright CBR,Inc. 2002 All Rights reserved. May not be reproduced.
Signs and tests
Diagnosis is based on the appearance of the lesion and can be confirmed by a skin biopsy. The health care provider should examine the lesion to rule out other disorders and to determine other underlying disorders.
In people with normal immune systems, the disorder usually disappears spontaneously over a period of months to years. The lesions may be extensive in people with AIDS or other conditions that affect the immune system. Individual lesions may be removed surgically, by scraping, de-coring, freezing, or through needle electrosurgery. Surgical removal of individual lesions may result in scarring. Medications, such as those used to remove warts, may be helpful in removal of lesions.
Expectations
Individual lesions of molluscum contagiosum usually disappear within about 2 - 3 months. Complete disappearance of all lesions generally occurs within about 6 - 18 months. The disorder may persist in immunosuppressed people.
Complications
* Persistence, spread, or recurrence of lesions
* Secondary bacterial skin infections
Calling your health care provider
Call for an appointment with your health care provider if you have symptoms suggestive of molluscum contagiosum. Also call for an appointment with your health care provider if lesions persist or spread, or if new symptoms appear.
Prevention
Avoid direct contact with the skin lesions.
Total abstinence is the only fullproof way of avoiding molluscum virus and other STDs. You can also avoid STDs by having a monogamous sexual relationship with a partner known to be disease-free.
Male and female condoms cannot fully protect you, as the virus can be on areas not covered by the condom. Nonetheless, condoms should still be used every time the disease status of a sexual partner is unknown. They reduce your chances of getting or spreading STDs. Use them with spermicide with nonoxynol 9.
References
Cohen J, Powderly WG. Infectious Diseases. 2nd ed. New York, NY: Elsevier; 2004:2053-2056.
Kauffman CL. Molluscum contagiosum. eMedicine. January 6, 2005. Available online at http://www.emedicine.com/derm/topic270.htm Accessed October 31, 2005.
Update Date: 10/31/2005
Updated by: Thomas A. Owens, M.D., Departments of Internal Medicine and Pediatrics, Duke University Medical Center, Durham, NC. Review provided by VeriMed Healthcare Network.
The global eradication of smallpox through the WHO campaign is the most outstanding example of what could be achieve through international cooperation. As a result, poxviruses have been relegated to the position of relatively unimportant human pathogens.
A. Properties
The family of poxviridae is divided into 6 genera, with species within each genera closely related.
Poxviruses are the largest viruses known
dsDNA enveloped virus, bricked shaped virions 200-250 * 250-300 nm in diameter. 2 morphological forms are seen: M (mulberry) and C (capsule) forms that are interconvertable. Internally, poxviruses have a biconcave "nucleoid" and 2 lateral bodies.
Inside the cell, the virion often has a double membrane. The lateral bodies contain various enzymes essential for virus replication.
>100 polypeptides have been demonstrated in vaccinia.
Poxviruses are very easy to isolate and will grow in a variety of cell cultures and will produce pocks on the chick chorioallantoic membrane (CAM)
B. Smallpox
Smallpox was transmitted by respiratory route from lesions in the respiratory tract of patients in the early stage of the disease. During the 12 day incubation period, the virus was distributed initially to the internal organs and then to the skin. Variola major caused severe infections with 20-50% mortality, variola minor with <1% mortality. Management of outbreaks depended on the isolation of infected individuals and the vaccination of close contacts. The vaccine was highly effective. If given during the incubation period, it either prevented or reduced the severity of clinical symptoms. The origin of the vaccine strain is not known, it is thought that it may have been horsepox which is now an extinct disease.
The eradication of smallpox
Smallpox was eradicated from most countries in Europe and the US by 1940s. By the 1960s, smallpox remained a serious problem in the Indian subcontinent, Indonesia and much of Africa. The WHO listed smallpox as the top on the list for eradication in 1967. There were certain features of smallpox which made it a highly eradicable disease. (see table below). The WHO smallpox eradication unit was set up in 1967. The initial strategy was separated into 3 phases;
1. Attack phase - This applied to areas where the incidence of smallpox exceeded 5 cases per 100,000 and where vaccination coverage was less than 80%. Attention was given to mass vaccination and improvement in case surveillance and reporting. This phase lasted from 1967-1973. A large amount of financial resoureces were provided for setting up surveillance centres and reference centres. Priority was given to Brazil, sub-saharan African, S.Asia and Africa. Brazil and Indonesis were thought to be the easiest countries to eradicate the virus from. In fact by 1973, smallpox had been eradicated from Braziland Indonesia. It was decided it was time to go on to the consolidation phase.
2. Consolidation Phase - In areas where the incidence was less than 5 cases per 100,000 and vaccination coverage exceeded 80%, the objective was the elimination of smallpox. Vaccination uptake was to be maintained and surveillance improved. Facilities should be made available for isolation.
3. Maintenance Phase - once smallpox had been eliminated, it was essential it was not reintroduced. This phase was entered in 1978. In 1980, the world was declared to be free of smallpox.
It soon became clear that smallpox could not be eradicated with mass vaccination alone. In some countries, it was not possible to achieve a smallpox vaccination uptake rate of 80%. More attention was therefore paid to case tracing and isolation procedures. Experience in West Africa and Indonesia had shown that smallpox can be eliminated without mass vaccination, provided that a high rate of case detection was achieved. The Indian subcontinent was a special problem because of its large size and population. It provided a reservoir for variola major infection. Extra attention was paid to search out unnotified cases that proved to be highly effective. The last cases of variola major occurred in the Indian subcontinent in 1975. The last case of variola minor occurred in Somalia in 1977. The last cases of smallpox occurred in a Birmingham laboratory in 1979. It was estimated that the smallpox eradication campaign costed US $312 million. If smallpox had not been eradicated, routine efforts to control smallpox would have costed US $1000 million. The success of smallpox eradication was due to the involvement of an international agency which was able to cross national barriers. The following were features that made smallpox an eradicable disease;
1. A severe disease with morbidity and mortality
2. Considerable savings to developed non-endemic countries
3. Eradication from developed countries demonstrated its feasibility
4. No cultural or social barriers to case tracing and control
5. Long incubation period
6. Infectious only after incubation period
7. Low communicability
8. No carrier state
9. Subclinical infections not a source of infection
10. Easily diagnosed
11. No animal reservoir
12. Infection confers long-term immunity
13. one stable serotype
14. Effective vaccine available
Other Poxviruses
1. Monkeypox
Monkeypox was first isolated from monkeys in 1958, but it was not until 1970 that it was associated with human disease. To date, over 400 cases have been investigated, mainly from Zaire. The pathogenesis and clinical features for monkeypox is the same as for smallpox. The main differences are a greater degree of lymphadenopathy and a lower capacity for case-to-case spread. Most cases occur in unvaccinated children. The mortality in human monkeypox is appreciable, being in the order of 10%. The management of human monkeypox is the same as for smallpox. Human monkeypox has not been detected outside West Africa. Although monkeypox was first isolated from monkeys, there is no evidence that African monkeys act as the reservoir. The most likely candidate for reservoir is the African squirrel. One important difference between human monkeypox and smallpox is the lower capacity for human spread. The attack rate among unvaccinated contacts is 9% in contrast to >37% for smallpox. Laboratory workers studying monkeypox should be vaccinated.
2. Vaccinia
Vaccination with vaccinia was associated with certain risks. Complications ranged from mild reactions and fatal encephalitis. The overall incidence of complications was around 1/800 although the more severe forms occurred only in 15 per million vaccinees. Recent interest has focused on the possible usage of vaccinia as a vector for immunization against other viruses. It is possible that certain changes can be made to the vaccinia genome which makes it less likely to develop side effects.
3. Cowpox
Cowpox is a relatively unimportant zoonosis which has only been isolated in Britain and Europe. Infection has been described in humans, cows and cats. Infection in humans usually remain localized, often producing a lesion which is similar to that caused by vaccination, although the inflammatory response is greater and general constitutional symptoms such as fever and myalgia may be present in some cases. In humans, lesions are usually restricted to the hands, but may also be transferred to the face. EM is generally used for the diagnosis of infection. The virus will also grow well on CAM. Human cowpox usually respond to treatment with antivaccinia immunoglobulin, but its use should be restricted to the most severe cases. Although cowpox was first isolated form cattle and farm workers. There is no evidence that cattle serve as the reservoir. In fact, cowpox is very rare in cattle. It has been suggested that the reservoir is actually a small rodent but this is not proven.
4. Parapoxviruses
Parapoxvirus infections are widespread in sheep, goats and cattle and relatively unimportant but common human infections occur. Infections in cattle and humans are usually referred to as pseudocowpox, paravaccinia or milker's nodes. Those in sheep and goats as orf. The viruses are closely related and the nomenclature of the human disease is based on the identity of the host form which the infection was acquired. (orf from sheep and pseudocowpox from cattle). Infection occurs via small cuts and abrasions in all hosts and is usually localized. Although the lesions are similar to the early lesions of cowpox and vaccinia, true macrovesicles do not form. In humans, lesions usually occur on the hand but may be transferred to the face. The laboratory diagnosis is usually made by EM. The virus may also be isolated in human, bovine and ovine cells but such investigations are not part of routine diagnostic virology. Parapoxvirus infections occur worldwide, and are of considerable importance. A survey carried in New Zealand showed that 1.4% of workers in the meat industry became infected in 1 year. The lesions are surprisingly painless and thus there is probably substantial under-reporting. Idoxuridine had occasionally been prescribed for treatment but no trials have been carried out to prove the efficacy of treatment. Prevention of human infection is difficult. Reasonable precautions should be undertaken when handling infected animals.
5. Molluscum Contagiosum
Molluscum contagiosum is a specifically human disease of worldwide distribution. The incubation period varies from 1 week to 6 months. The lesion begins as a small papule and gradually grows into a discrete, waxy, smooth, dome-shaped, pearly or flesh-coloured nodule. Usually 1-20 lesions but occasionally they may be present in hundreds. In children, the lesions are found on the trunk and the proximal extremities. In adults they tend to occur on the trunk, pubic area and thighs. Individual lesions persist for about 2 months, but the disease usually lasts 6 to 9 months. Constitutional disturbance is rare. The disease occurs world-wide and is spread by direct contact or fomites. In general it tends to occur in children. The disease by may transmitted from skin to skin after sexual intercourse. A diagnosis can usually be made on clinical appearance alone. The diagnosis can be supported by EM. Unlike other poxviruses, molluscum have not been demonstrated to grow in cell culture. Infection is usually benign and painless, with spontaneous recovery in most cases. Where treatment is required for cosmetic reasons, various procedures are available such as curretage, cryotherapy with liquid nitrogen, silver nitrate etc. which are routinely used for the removal of warts.
6. Tanapox
Tanapox is a poxvirus infection first recognized in 1957 in the Tana River area of Kenya. It is a zoonosis, human cases have only been seen in the Tana valley and Zaire. The distribution of the virus and the real extent of the human infection is not known, as is the method of transmission of infection. The virus produces a mild febrile illness with one or two skin lesions. The virus does not grow in CAM but will grow in a variety of cell lines.
http://virology-online.com/viruses/Poxviruses.htm
New Treatment Options
Essential oils from plants in the Myrtle family have demonstrated anti-viral activity, both in cell culture and in some limited clinical studies. The essential oil of Melaleuca alternifolia is one such species with documented antibacterial, anti-fungal, and anti-viral actions. A recent published clinical study demonstrated the effectiveness of an essential oil preparation in the treatment of molluscum in children (Burke BE, Baille JE, Olson R. Treatment of molluscum contagiosum in children with essential oil of Australian lemon myrtle. Biomedicine & Pharmacotherapy, 2004; vol 58). A product based on this study utilizing essential oil of Melaleuca (tea tree oil) in conjunction with iodine and other essential oils is marketed as ZymaDerm. The data presented by the company reports better than a 90% success rate after 4-6 weeks. This represents a significant advancement in as much as the treatment is painless, making it a viable alternative to currently painful, invasive treatments, or worse yet, useless hucksterism often promoted on the internet.