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Three Part Question

In [a child with a verruca (plantar wart)] does [wearing an occlusive dressing or sock while swimming] reduce [transmission]?

Clinical Scenario

The son of one of the authors came home from school with a letter explaining that prior to swimming each term, children would have their feet checked for verrucas. School policy stated that if a verruca was discovered a protective sock must be worn. Many public swimming pools have no restrictions on children swimming with verrucas, and in view of conflicting policies we wondered whether verrucas were transmitted during swimming and if wearing verruca socks was a necessary intervention.

Search Strategy

Cochrane, Medline and Embase.
Secondary sources: Cochrane—none. Primary sources: Medline 1966 to present (verruca OR plantar wart) AND swim LIMIT to English language. Embase: same search strategy—no additional papers.

Search Outcome

Altogether 7 articles found, 2 relevant plus 3 from manual search.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Allen WH and Dickinson VA. 1968,	14,075 pupils from 40 primary and secondary schools	Random sample of 40 schools in Hertfordshire (level 4)	Prevalence of plantar warts	Prevalence of 2.9% for secondary schools and 1.8% for primary schools	Prevalence appeared greater in those using heated covered pools (4.02%), compared to those using pools, which were not covered and heated either at school (2.91%) or public pools (2.10%). Authors concluded that difference may be due to differing periods of exposure. No statistically significant difference was found between the groups that did gymnastics in barefoot compared to plimsolls
Tranter AW, 1969	Pupils from 6 junior schools	Junior schools chosen at random (level 4)	Incidence of plantar warts and the amount of swimming undertaken	Correlation coefficient was calculated giving a significant positive value at the 5% level suggesting a positive relationship between the amount of swimming and the incidence of warts	Evidence suggested that if a school has its own pool, used only by its pupils and if they were examined twice/term and children with plantar warts excluded the incidence of warts will decline. If the school uses a communal pool the incidence will not decline
Bunney MH, 1972,	68 matched pairs of swimmers. One of the pair wore "Plastsocks" and the other bare feet (control group)	Paired (level 2b)	Incidence of new plantar warts in the "Plastsocks" group versus the control group	During the study period the sock group was entirely free from plantar warts, while the control group developed 9 new plantar warts (p<0.01)	The study did not look at the effectiveness of "Plastsocks" in preventing the transmission of infection
Gentles JC and Evans EGV, 1973,	773 bathers at a public swimming bath	Random sample: 9.3% of bathers (level 2c)	Incidence of verrucas	Overall incidence of verrucas was 4.8%, with 0.76% in adults, 6.9% in juveniles. Incidence of 10.2% during school swimming sessions and 5.1% during public swimming sessions (p<0.05)	The incidence of veruccas was noted to be higher than previously recorded. Authors conclude swimming baths are involved in the "vicious circle" of infection and floor contamination
Johnson LW, 1995	146 adolescents aged 10–18 who used locker rooms	Comparison of 80 pupils who only used locker rooms, with 66 members of a swim club who used locker rooms plus communal showers (level 4)	Incidence of plantar warts	Significant difference in prevalence between those who used public shower rooms and locker rooms (27%) compared to those who used only locker rooms (1.25%) (2=15.46, df=1, p=0.001)	Shower rooms proposed as a risk factor, with the warm, moist environment important for viral transmission. Author states that he is conducting a follow up study to determine whether the incidence of plantar warts among shower room users (swimmers) can be reduced by limiting foot-to-floor contact, but subsequent paper not found in search

Comment(s)

The Department of Health Guidance on infection control in schools and nurseries (1) suggests that affected children may go swimming but that verrucas should be covered. Our search revealed little up to date information on the prevalence of verrucas in schoolchildren, or the effectiveness of preventive measures. One paper studied protective footwear, but this study looked at the role of protective footwear in preventing the acquisition of plantar warts in unaffected individuals. It did not examine the prevention of spread by affected individuals wearing footwear (4). There were no studies looking at the effectiveness of simply covering a plantar lesion with an adhesive dressing in the prevention of spread. Only one study looked at the prevalence of plantar warts in swimmers compared to non-swimmers (6). This study found that adolescents who used locker rooms plus communal showers at a swim club had a significantly higher prevalence of warts than young people using only locker rooms. Three studies looked at the prevalence of verrucas in swimmers. One (2) found a greater prevalence of warts in those swimming in heated covered pools compared to uncovered pools, concluding that this difference may be accounted for by a differing period of exposure. Another (3) found a positive correlation between the amount of swimming and the incidence of warts. The third (5) found a higher incidence of verrucas in those swimming during a school session than during a free-swimming session.

Clinical Bottom Line

Swimming is part of the national curriculum up until the end of key stage 2, by which time children are expected to be able to swim 25 metres. Although studies have shown an association between verrucas and swimming, none have looked at the increased risk of verruca acquisition with swimming. No studies have considered the effectiveness of protective socks/dressings in preventing transmission. Expecting children to wear protective socks, without evidence of their effectiveness, may stigmatise children and put them off swimming altogether.

References

1. Allen WH, Dickinson VA. The problem of verrucae. The Medical Officer 1968;17 May:261–4.
2. Tranter AW. A scheme for the prevention of plantar warts. The Medical Officer 1969;6 June:317–22.
3. Bunney MH. Prevention of plantar warts by the use of protective footwear in swimming pools. Community Med 1972;10 March:127–9.
4. Gentles JC, Evans EGV. Foot infections in swimming baths. BMJ 1973;3:260–2.
5. Johnson LW. Communal showers and the risk of plantar warts. J Fam Pract 1995;40:136–8.
6. Department of Health. Guidance on infection control in schools and nurseries. DoH London: Department of Health, 1999.