Infectious disease <ul><li>Measles (Rubeola) </li></ul><ul><li>Humans are the only natural host for measles virus </li></ul><ul><li>RNA containing, pleomorphic, enveloped paramyxovirus with a worldwide distribution. </li></ul><ul><li>measles is spread by direct contact with droplets of respiratory secretions. </li></ul>
measles <ul><li>The incubation period of measles is 10 to 14 days </li></ul><ul><li>followed by a prodromal phase that corresponds to the secondary viraemia. </li></ul><ul><li>The prodromal symptoms are cough, coryza, conjunctivitis, fever and anorexia and normally last for 2-4 days. </li></ul>
Measles <ul><li>During this period the epithelium of the entire respiratory tract is inflamed and reddened and patients are at their most infectious: croup, bronchiolitis and viral pneumonitis </li></ul><ul><li>Warthin finkeldey bodies </li></ul>
measles <ul><li>Koplik's spots are found towards the end of the prodrome and can still be seen during the first two days of the skin eruption. </li></ul><ul><li>the enanthem can be seen as minute bluish white spots on an erythematous base, varying in number from a few to hundreds. The spots are best seen in the buccal groove at the level of the lower premolars. </li></ul><ul><li>they can sometimes be seen in the conjunctiva. </li></ul>
measles The minute white dots seen on the inflamed buccal mucosa are koplik’s spots
Measles Measles, with koplik’s spot on the buccal mucosa. This is an unsually severe case, enough to cause considerable discomfort when feeding.
Measles <ul><li>The measles rash appears first on the temples and behind the ears then spreads rapidly over the face and down the body to involve the trunk and limbs (including the palms and soles). </li></ul><ul><li>Rash- is generalized, maculopapular, erythematous and often somewhat purplish in tinge. Individual spots are irregular in shape and of variable size. </li></ul>
Measles The rash often begins behind the ears. Koplik’s spots were visible on the buccal mucosa.
Measles The rash is already prominent on the face and is spreading down the body onto the trunk and extremities
measles <ul><li>After a few days of uncomplicated measles, fever subsides and the rash fades at the same time. </li></ul><ul><li>Capillary leakage at the height of the illness is revealed by transient purpura (post-measles staining) in the distribution of the rash. </li></ul><ul><li>The common complications of measles are secondary bacterial infections of the respiratory tract (particularly pneumonia and otitis media </li></ul>
Measles During the healing phase, a transient brown staining of the skin maybe apparent in white children.
Rubella (German Measles) <ul><li>Rubella virus, an enveloped RNA virus in the Togaviridae family </li></ul><ul><li>spread by droplets of respiratory secretions. </li></ul><ul><li>The large epidemics of infection that previously occurred every 5-10 years have been prevented in countries where vaccination is widespread. </li></ul>
Rubella <ul><li>The incubation period of rubella averages 18 days with a range of 12-23 days. </li></ul><ul><li>The clinical features of rubella (notoriously) vary from patient to patient. </li></ul>
Rubella <ul><li>the lymphadenopathy may be generalized </li></ul><ul><li>posterior cervical and suboccipital lymph nodes are characteristically enlarged. </li></ul><ul><li>It may last for several weeks. </li></ul><ul><li>The exanthem of rubella is a discrete, pink, diffuse, macular rash. </li></ul><ul><li>rash is most marked upon the face and trunk on the first day then spreads peripherally along the limbs on the second day before disappearing on the third and fourth day. </li></ul>
Rubella Although the rash is quite profuse, the elements are discrete except on the face, which shows general flushing.
Rubella A typical diffuse macular rash over the trunk.
Rubella <ul><li>There is no specific therapy for rubella. </li></ul><ul><li>Live vaccines are used in an attempt to prevent congenital rubella. </li></ul><ul><li>Other countries vaccinate girls as they approach puberty. </li></ul><ul><li>Despite specific immunity, reinfection with rubella virus is now known to occur. </li></ul>
Roseola infantum (exanthem subitum) <ul><li>This disease of infants aged 6 months to 3 years. </li></ul><ul><li>Causative agent- Human Herpes Virus type 6 (HHV-6) </li></ul><ul><li>The incubation period is 10-15 days and there is usually no prodromal illness. </li></ul>
Roseola infantum Human herpes virus type 6. Electro micrograph of extracellular, mature, enveloped HHV-6 virus budding from a cell.
Roseola infantum Electro micrograph of HHV-6 capsids in a cell nucleus.
Roseola infantum <ul><li>First symptom is high fever, sometimes with lymphadenopathy, and this lasts for a few days during which the child appears quite well. </li></ul><ul><li>As the fever resolves it is followed by a maculopapular rash of central distribution which itself lasts for a few hours to a few days </li></ul><ul><li>Apart from occasional febrile convulsions, complications are most unusual and immunity to infection appears lifelong. </li></ul>
Roseola Infantum Non specific maculopapular rash with a central distribution developed as fever, subsiding on the third of illness.
Erythema infectiosum (Fifth disease) <ul><li>Etiological agent- Parvovirus type B19 was only made in 1984. This is a small DNA virus. </li></ul><ul><li>Causes a biphasic illness in susceptible volunteers. </li></ul><ul><li>About one week after infection there is a viraemia for a few days. At this time there are non-specific symptoms but 7-10 days later there is rash and arthralgia. </li></ul>
Erythema Infectiosum <ul><li>Fifth disease is seen usually in school-age children. </li></ul><ul><li>The incubation period is 4-14 days and infection is probably spread by droplets. </li></ul><ul><li>A short prodrome of fever may occur in adults but is rare in children in whom the rash is often the only feature. </li></ul>
Erythema Infectiosum <ul><li>The rash has three stages </li></ul><ul><li>First is the `slapped cheeks' appearance. </li></ul><ul><li>Second- A variable, often reticular rash on the limbs. </li></ul><ul><li>Third stage, this peripheral rash may appear to settle, only to reappear with temperature, exercise or emotion. </li></ul><ul><li>Some patients have systemic features with fever, adenopathy and gastrointestinal symptoms. </li></ul>
Erythema Infectiosum The rash on face is frequently described as having a “slapped checks appearance.”
Erythema Infectiosum The rash on the extremities often clears centrally to produce a lace-like appearnce.
Erythema infectiosum <ul><li>Parvovirus-specific IgM can be detected and used as a diagnostic test. </li></ul><ul><li>After acute infections adults are likely to remain fatigued and depressed for several weeks. </li></ul><ul><li>It is also recognised that parvovirus infection may affect the fetus and lead to spontaneous abortion or hydrops fetalis. </li></ul>
Herpes Simplex <ul><li>The herpes viruses are all large DNA viruses and herpes simplex virus (HSV) is typical. </li></ul>
Herpes simplex Electron micrograph of HSV from vesicle fluid.
Herpes simplex <ul><li>The virus is unable to survive for long in the environment and does not penetrate intact keratinized skin. Transmission is principally by intimate contact. </li></ul>
Herpes simplex <ul><li>Primary HSV skin infections may occur at any site as a result of direct inoculation of the virus through traumatized skin. </li></ul><ul><li>This may occur as a result of wrestling (herpes gladiatorum) or other contact sports such as rugby football. </li></ul><ul><li>by transfer of infection from oral sites to other areas via the fingers </li></ul>
Herpes Simplex Primary infection on the wrist of a young man.
Herpes Simplex Genital infection in an infant due to implantation of the virus carried on the hand from primary herpetic stomatitis.
Herpes Simplex <ul><li>Recurrent cutaneous HSV may also occur at any site and then may mimic herpes zoster . </li></ul><ul><li>Although there may be some prodromal symptoms of tingling or itching, systemic symptoms are not usually seen and the rash does not usually have a clear dermatomal distribution </li></ul>
Herpes simplex Recurrent infection in a zoster like distribution over the face.
Herpes simplex <ul><li>Patients whose cellular immunity is compromised by disease or immunosuppression are at increased risk of severe HSV infections. </li></ul><ul><li>Thus, patients with hematological or lymphoreticular malignancies, those who have received organ or bone-marrow transplants and patients with AIDS are at particular risk of severe and persistent cutaneous disease due to HSV. </li></ul>
Herpes simplex Severe lesions with skin necrosis in a patient with leukemia.
Herpes simplex <ul><li>The diagnosis of HSV infections of the skin can usually be made upon clinical grounds. </li></ul><ul><li>If there is any doubt, vesicle fluid can be examined for virus particles by electron microscopy, or scrapings from the floor of suspect lesions can be examined by the Tzanck test. </li></ul>
Herpes simplex T zanck test preparation showing multinucleate giant cell.
Varicella (Chicken Pox) <ul><li>Varicella-zoster virus (VZV) is morphologically indistinguishable from herpes simplex virus. </li></ul><ul><li>It is transmitted from person to person by the respiratory route and the virus may arise either from the oropharynx of a patient late in the prodrome of the illness or from vesicular fluid during the first 3-4 days of each skin lesion. </li></ul>
Varicella Chicken Pox <ul><li>The incubation period of varicella is usually 14 or 15 days with a range of 11-20 days. </li></ul><ul><li>In children there is rarely any prodromal illness; fever and rash are the initial manifestations of infection. </li></ul><ul><li>Adults more commonly have myalgia, arthralgia, fever and chills for 2-3 days before the rash appears. </li></ul>
Varicella Chicken Pox <ul><li>The eruption of chicken pox is discrete, varying in severity from a few spots to a very profuse rash. </li></ul><ul><li>Each lesion starts as a tiny macule which rapidly becomes papular and then vesiculopustular. </li></ul><ul><li>The rash often starts on the scalp. </li></ul>
Varicella Chicken Pox Electron micrograph of enveloped virus particles from vesicle fluid.
Varicella Chicken Pox <ul><li>The vesicles are very superficial and there is little or no induration around the lesion. </li></ul><ul><li>After a few hours to a few days, the lesion is scratched or becomes inspissated: in either case the fluid is replaced by a central scab . </li></ul>
varicella Within a few days of early rash, most of the lesion have become scabs of varying size.
varicella <ul><li>The distribution of chicken pox is central. </li></ul><ul><li>The rash is more dense on trunk and face and becomes less so peripherally. </li></ul><ul><li>Lesions are often found on the mucous membranes of the conjunctivae or mouth and. </li></ul>
varicella General view of severe rash showing characteristic distribution of lesions, with lesions most numerous centrally.
varicella Lesions commonly occur within the mouth.
varicella <ul><li>Varicella skin lesions may be more numerous on an area of skin that has been subject to sunburn, irritation or mechanical trauma. </li></ul>
varicella In this young boy the lesion are most confluent in the antecubital fossa and over the neck areas where he had previously suffered from atopic eczema
varicella <ul><li>In the normal individual secondary infection of the lesions with staphylococci or streptococci is the only frequent complication although haemorrhagic chickenpox with disseminated intravascular coagulation and pneumonitis occasionally occur </li></ul>
varicella Scratching of the lesions not in frequently leads to secondary infection with streptococci or staphylococci and hence cellulitis around individual lesions.
varicella Purpura fulminans and disseminated intravascular coagulation complicating chicken fox in immunocompetent adult woman.
varicella <ul><li>The clinical diagnosis of varicella is usually not difficult. </li></ul><ul><li>if laboratory assistance is required then it can be done by finding typical herpes virus particles in the vesicular fluid by electron microscopy. </li></ul><ul><li>The appearances are identical to those of HSV and only culture will distinguish between the different herpes viruses. </li></ul>
Herpes Zoster (shingles) <ul><li>Following the initial infection with VZV, the virus, as for other herpesviruses, persists in the individual in a latent form. </li></ul><ul><li>VZV remains in the dorsal root ganglia but the exact nature of the latent state is unknown. </li></ul>
Shingles <ul><li>Cellular immune system is chiefly responsible for maintaining the virus in the latent state as anything that depresses this form of immunity is associated with a more frequent reactivation of VZV. </li></ul>
Shingles <ul><li>When it is seen in a young child who has never suffered from varicella , the virus will have been transmitted in utero from the mother who had chickenpox during pregnancy. </li></ul><ul><li>Following reactivation of virus there is degeneration of the cells of the dorsal root ganglion and the virus then affects the area of skin supplied by the sensory nerves from that ganglion. </li></ul>
Shingles When it occurs in a child as young as this 8 month old it is often as a result of primary infection in utero.
Shingles High power view of base of vesicle showing inclusion bodies.
Shingles <ul><li>The resultant illness usually begins with pain in the areas of distribution of the affected posterior nerve root(s), followed by the rash. </li></ul><ul><li>The rash is unilateral and involves 1-3 adjacent dermatomes. </li></ul><ul><li>There is often a faint erythema before the typical vesiculopustular eruption. </li></ul><ul><li>Any dermatome(s) may be involved although the thoracic dermatomes are affected in about half the cases. </li></ul>
Shingles A bond of faint erythema in the distribution of an intercoastal nerve, the first physical sign of shingles, can be seen. The patient had been in pain for several days.
Shingles A typical mature rash showing regular vesicles of varying size with an erythematous base.
shingles <ul><li>The single most commonly involved dermatome is that of the trigeminal nerve. </li></ul><ul><li>The ophthalmic branch is most commonly affected but shingles in the distribution of the maxillary or mandibular branch is occasionally seen. </li></ul>
shingles Rash involving maxillary division of the trigeminal nerve.
shingles The most frequently affected dermatome is that of the opthalmic division of the trigeminal nerve.
shingles Lesions in the distribution of the maxillary division of the trigeminal nerve.
shingles Lesion in the distribution of the mandibular division of the trigeminal nerve.
Shingles <ul><li>The complications of herpes zoster </li></ul><ul><li>Ramsay-Hunt syndrome - a variety of other neurological complication and ocular problems after trigeminal involvement. </li></ul><ul><li>The most frequent problem is, however, post-herpetic neuralgia which is more common in the elderly </li></ul>
Molluscum Contagiosum <ul><li>Molluscum contagiosum is a benign disease caused by the poxvirus family and spread by close human contact. </li></ul><ul><li>The lesions are characteristic firm white nodules which vary greatly in number and tend to persist for a period of a few weeks to a few months. </li></ul><ul><li>Sometimes they may be found in clusters along a scar. </li></ul>
Molluscum Contagiosum Electron micrograph of the virus, appears as a cylindrical shape with rounded ends and a criss-cross pattern of nucleoprotein strands.
Molluscum Contagiosum Several fleshy lesions with ambilicated centers on the face. They tend to regress and disappears after some months.
Molluscum Contagiosum <ul><li>The lesions may be single or multiple. </li></ul><ul><li>Each begins as a reddish papule that becomes a large haemorrhagic pustule on a red base. </li></ul><ul><li>Lymphadenopathy may be present. </li></ul><ul><li>The lesions are usually, but not always , on the hands. </li></ul>
Molluscum contagiosum Orf. Papular lesions on the hand. Patient also has severe erythema multiforme with arthritis. The proximal interphalangeal joints can be seen to be swollen.
Molluscum contagiosum Orf. Large pustular lesion on the hand of a farm worker.
Molluscum Contagiosum Orf. Early lesion on the face.
Molluscum contagiosum <ul><li>The pustule may become umbilicated and then rupture to leave an ulcerated nodule with a grey crust. </li></ul><ul><li>Erythema multiforme may occur after a week or two. </li></ul>
Molluscum contagiosum <ul><li>The diagnosis is usually made clinically but can be confirmed if necessary by electron microscopy, which reveals the large, ovoid virus particles. </li></ul>
Wart <ul><li>Papilloma viruses, which produce human warts, are small DNA viruses . </li></ul><ul><li>There are more than 50 different types of human papilloma virus (HPV) . </li></ul><ul><li>Common warts (verrucae vulgaris), plantar warts (verrucae plantaris), flat or planar warts (verrucae plana) and condylomata acuminata </li></ul>
Warts Electron micrograph showing papiloma virus.
Warts <ul><li>Most common warts are 2-10mm in diameter (although they may coalesce to larger masses), flesh-coloured or brown, keratotic papules with a rough surface. </li></ul>
warts <ul><li>On mucosal surfaces the warts may be filiform with a narrow base and finger-like projections. </li></ul><ul><li>Flat warts ares smaller, flat topped, non-scaling, skin-coloured papules and seen especially in groups upon the hands, neck or face. </li></ul>
warts Common warts. Hand and fingers are common site.
warts <ul><li>Treatment with cryosurgery or with topical lactic and salicylic acid paint is used for common or flat warts. </li></ul>
warts <ul><li>End of Viral Skin Diseases </li></ul>