EPIDEMIOLOGY AND CONTROL OF FUNGAL INFECTIONS

Dr IgbinedionMBBS, MPH, FRSPH

SUPERFICIAL FUNGAL INFECTIONS

Affects the skin, nails and hair Dermatophytes, yeast and mould are

the main fungi that cause superficial skin infections

There are three genera of dermatophytes that cause superfical fungal infections and they are:

Microsporum (affects hair and skin)Trichophyton(affects skin, hair and nails)Epidermophyton (affects nails and skin)

The dermatophytes can be classified into three groups based on their habitats

HumansAnimals Soil

It should be noted that the skin is a normal habitat for some of these fungi

Distribution

There is worldwide distribution Commonly seen in daily practice Geographic distribution of these

dermatophytes varies with different presentations in different parts of the world

Migration, drug therapy, lifestyle and socioeconomic factors all influence the changes that have been observed in the epidemiology of these infections

Distribution (contd)

Affects all ages and sexes but more commonly found in children

Higher incidence in tropical countries and may be attributed to the warm climate (fungi thrive well in moist environments) and poor infrastructure (lack of water)

Determinants

Man is the main reservoir of infection but as mentioned earlier, animals and soil play a part

Transmission can be direct or indirectDirect transmission e.g. during sexual

intercourse, the moist surface of the lesion allows for easy transfer of the organism

Indirect transmission is by close body contact, sharing of clothing, towels, razors, hair clippers

Determinants (contd)

Incubation period 4-14 days Host immunity is an important factor.

Drug therapy, e.g. steroids or other immunosuppressive drugs can increase susceptibility to developing infections. Poor personal hygiene also increases susceptibility

Clinical Features

Affects the body, scalp, nails, moist skin of the feet or groin

Tinea corporis (ringworm) produces lesions on the skin that spread out from the centre with depigmentation

Tinea capitis affects the scalp and causes areas of baldness. More common in prepubertal children

Tinea (Pityriasis) versicolor caused by the yeast malassezia furfur can be mistaken for leprosy because of the blotchy hypopigmentation

Clinical Features (contd)

Tinea pedis affects the feet and can cause scaling. Common in men who wear shoes and socks all day long

Tinea cruris usually only found in the groins and occurs more in males. May extend to thigh and buttocks

Tinea unguium affects the nails, with toenails more affected than fingernails. Usually found along with tinea pedis

Diagnosis

Clinical diagnosis is usually sufficient for diagnosis

Laboratory diagnosis can be done by staining or culturing scrapings of skin and scales, and plucked out diseased hairs (in cases of T. capitis)

Treatment

Topical antifungals- clotimazole, Whitfield’s ointment

Systemic antifungals- griseofulvin, terbinafine, fluconazole, itraconazole, ketoconazole

Anti bacterials in cases of secondary bacterial infection

Prevention and Control

Primary preventionHealth education on the cause of

diseaseAdequate housing facilities to

prevent overcrowdingAdequate water supplyAdequate protective clothing and

avoidance of moist feetAvoid sharing clothes and other

items

Prevention and Control (contd)

Secondary preventionEarly detectionPrompt treatment

Advantages Reduces rate of transmission and

infectivity Reduces morbidity and illness

duration Limits disability that may result from

secondary bacterial infection

Prevention and Control (contd)

Tertiary preventionRehabilitation

Surveillance is important and should be carried out especially in children to examine head, feet and groin.

CANDIDIASIS

Dr IgbinedionMBBS, MPH, FRSPH

Caused by yeast of the genus Candida There are about 20 Candida species that

can infect man but the most common is Candida albicans

Candida yeasts are normally found in the skin and mucous membranes but problems arise when there is overgrowth of the organisms in predisposed conditions such as pregnancy, infancy, diabetes, moist environments, immunosuppression, etc.

Candida infection can be found in skin folds, moist areas such as webspaces, genitals and areas covered by diaper

Incubation period is 1 week Can be transmitted directly or

indirectly through sexual intercourse

Types

Oropharyngeal candisiasis aka Thrush- This causes white plaques on the oral mucosa which may bleed when removed

Vulvovaginal candidiasis- causes itching and soreness with resultant erythema and edema of the vulva and vagina

Diagnosis

Clinical Laboratory- Gram staining of

samples which shows yeasts with pseudohyphae, pathognomic of tissue invasion

Treatment

Topical or systemic antifungals depending on the extent of disease

NystatinClotrimazoleCarnestin creamFluconazole ItraconazoleKetoconazole

References

Ameen, M. (2010). Epidemiology of superficial fungal infections. Clin dermatol; 28(2): 197-201

King-man, H.O. and Cheng, T. (2010). Common superficial fungal infections- a short review. The Hong Kong Medical Diary; vol 15: 23-27.

Webber, R. (2010). Communicable Disease Epidemiology and Control: A Global Perspective. 3rd edition.