Abstract: The deputy of health affairs of Kerman province encountered a report of Tinea capitis outbreak in one of the southern towns of the province in winter 2006 of which stated 1294 cases of Tinea capitis among primary school children that 86% of them were boys. The epidemiological and environmental investigation was conducted through a case-control study. The outbreak investigation showed that the risk of infection was significantly higher among subjects with a lower socioeconomic status, poor personal hygiene and a positive personal history of Tinea capitis. Improvement of living condition, public attention to personal hygiene and active case finding would be effective in decreasing and preventing Tinea capitis.
INTRODUCTION
Tinea capitis is a common fungal infection caused by Dermatophytes which is endemic in many countries (Brilhante et al., 2004; Razzaq Adel et al., 2007). This highly contagious disease is a worldwide public health problem particularly in school children (Razzaq Adel et al., 2007; Bassiri Jahromi and Khaksar, 2006) and it is rarely diagnosed in infancy and adulthood. Dermatophytes are a group of fungal infections, which are categorized to three major groups: Epidermophyton, Tricophyton and Microsporum, These tineas tended to use nail, hair and skin keratin as a nutritive material (Bassiri Jahromi and Khaksar, 2006; Millu and Hodgson, 1993). The epidemiologic pattern of this kind of disease differs from a country to another-even in a large country it differs from one region to another (Ilkit et al., 2007).
Epidemiologic studies in controlling and eradicating the disease are of great importance (Clayton and Hay, 1994). In January, 2006 an epidemiologic outbreak of Tinea capitis occurred in a community in Southern Iran. We conducted epidemiological investigation to determine the risk factors of the disease to implement control and preventive measures.
MATERIALS AND METHODS
Setting
The epidemic was happened in Manoojan city-one of the warmest cities
in the southern part of Kerman province (The greatest province throughout
the country). The total population of the city is 61000. It is located
1400 km South-west of Tehran. The area of the district is 4086 km2
and 98% of residents are farmers and shepherds. In November and December
2005 the reported cases from the city schools were not considerable so
the directors of the district health center of the city not to take it
serious, but in January, 2006 the number of case increased dramatically
and at the end of season, 1294 cases based on laboratory test results
and epidemiologic and clinical criteria were found positive of which 1118
cases were boys (86%). Ninety five percent of them were primary schools
students aged less than or equal to 12 years.
Case Definition
Three levels of case definition with increasing specificity were used.
Suspected cases were the ones which had clinical signs (such as: scalp
purities, scalp scaling, patchy or discrete alopecia) according to the
report of field health staff. The probable cases were the patients with
positive potassium hydroxide (KOH) microscopy. The confirmed cases were
the people with positive fungal culture.
Epidemiologic Investigation
In a case-control study, 400 primary school children were studied
using age-and sex matched controls randomly selected from the same schools
considering the high prevalence of cases in the primary schools. Cases
consisted of 200 children diagnosed as Tinea capitis based on clinical
signs and positive laboratory investigations (Hainer, 2003) and the remaining
200 subjects were defined as control group.
After the selection of cases and controls, the trained interviewers referred to their homes and after obtaining informed consent, the parents were questioned about type of residence (permanent or immigrant), family members, father occupation and income, existence of bathroom in their home, the number of taking a bath per week, adequate usage of soap and shampoo, occurrence of similar disease in the recent years or among the other members of the family, the presence of animals near home, the reference to barber shop (or haircutting at home). The frequency of the selected characteristics between cases and controls was compared by chi square test. The statistical analyses were conducted by SPSS V.15 Software.
RESULTS AND DISCUSSION
Trichophyton mentagrophytes was cultured from the specimens. The mean (±SD) age of the patients and controls were 9.6 (±0.2) and 9.9 (±1.8), respectively (p>0.05). In the patient group 89.0% were boys and in the control group 87.7% were boys (p>0.05). In Table 1, the relative frequency of each the studied variables is shown. The important risk factors of the disease were low income of the family, the absence of bathroom at home, inadequacy of bath taking in a week and history of disease in the recent years.
In the present study the role of different factors were verified in an outbreak of Tinea capitis in a city located in tropical region of Iran. Before discussing about the results the main limitation of the study should be mentioned. It was more logical to culture all specimens in the patient group though some authorities have shown that clinical diagnosis is accurate in more than 92% of laboratory confirmed cases so that they recommend empirical treatment of the patients solely based on clinical presentation (Hainer, 2003).
T. mentagrophytes as a Zoophilic dermatophyte was the cause of the epidemic. In a study conducted on 290 sporadic patients in Tehran, T. violaceum and T. mentagrophytes were diagnosed as the most and the least prevalent etiological agent agents, respectively (Bassiri Jahromi and Khaksar, 2006). One of the major differences of our study with the above mentioned study is related to the living conditions in the two areas. The epidemiologic pattern of Tinea capitis is closely related to social and geographical settings (Clayton and Hay, 1994).
| Table 1: | Comparison of background variables in the healthy (n = 200) and patient group (n = 200)* |
| *Values in parentheses shows percentage | |
The most prevalent etiologic agent in the United States has been shown to be T. tonsurans (Pomeranz et al., 1999) and it was of the second most prevalent agent in a study conducted in Spain (Rubio-Calvo et al., 2001).
It should be noteworthy that in the recent years in most of the developed countries a shift from Antropophilic to Zoophilic fungal infections has been documented (Rubio-Calvo et al., 2001).
Generally, Anthropophilic fungi are transmitted from human to human and the probability of asymptomatic carriage is relatively high, while Zoophilic fungi such as T. mentagrophytes are less likely lead to asymptomatic carriage (Ilkit et al., 2007).
In total, 86% of cases occurred during the outbreak were male which is compatible with other studies (Bassiri Jahromi and Khaksar, 2006; Rubio-Calvo et al., 2001). The higher susceptibility of boys to Tinea capitis in comparison to girls may be due to the later onset of puberty in boys (Sberna et al., 1993). The reason why the disease has primarily occurred in school children is that the fungistatic action of fatty acids of adult sebum has a potential role in inhibition of fungal growth (Bassiri Jahromi and Khaksar, 2006; Rubio-Calvo et al., 2001).
The probability of Tinea capitis was higher among those with a lower socioeconomic status, those who took bath less than once per week and those with no bathroom in their home (Table 1). The role of sanitation and personal hygiene in the development and spreading of outbreaks of Tinea capitis has been well documented in other studies (Leeming and Elliot, 1995; Svejgaard, 1995). During 1950s most of the Tinea capitis epidemics in Europe were seen in conditions of overcrowding, poor hygiene and poverty (Svejgaard, 1995).
Recent history of similar disease was reported in 4.5% of cases and 0.5% of controls (p<0.05) (Table 1). Although the fungal cause of the outbreak was zoophilic the possible role of asymptomatic cases should not be neglected (Ilkit et al., 2007; Pomeranz et al., 1999). So to control the outbreak active case finding should be considered especially among children (Ilkit et al., 2007).
Owing to zoophilic nature of the T. mentagrophytes it was expected that presence of animal pets or domestic animals in the child`s environment would be more prevalent in the case group rather than control (Vidotto et al., 1991). The results showed no significant difference in this regard which may be due to clustering effect and selection of both cases and controls from the same schools (Table 1).
In the patient group the percentage of the people who referred regularly to the public barbers was 19% and it was lower than control group (12%) which was marginally significant (p = 0.06) (Table 1). So it can be concluded that poor hygienic adherence of public barbers and comb sharing may be related factors to the propagation of epidemic (Bassiri Jahromi and Khaksar, 2006; Pomeranz et al., 1999).
CONCLUSION
In conclusion, the findings of this investigation demonstrate the public health importance of increasing efforts to promote the living condition and housing for the residents. Improvement of environmental health, public attention to personal hygiene and active case finding would be effective in decreasing and preventing Tinea capitis.