Samoan rates of impetigo nearly four times global average

Samoan school children have nearly four times the global average of cases of the contagious skin infection impetigo, according to a new study published in The Lancet.

In a new paper on impetigo (po’u) and scabies (utu o le pa’u) in Samoan children aged between four and 15 years, researchers report nearly 57.6 per cent of children had impetigo while closer to 14 per cent had scabies.

Of those infected, a third had active impetigo, and some showing more than a dozen active lesions on their bodies. 

In 2015, a review of global prevalence of impetigo in children found that at any one time, more than 162 million children are suffering from impetigo all over the world, and that among low or middle income countries, 8.4 and 14.5 per cent of children (respectively) had the infection.

Here in Samoa, that figure is quadrupled.

The study ‘Scabies and impetigo in Samoa: A school-based clinical and molecular epidemiological study’ was authored by several local health practitioners, including National Kidney Foundation clinical director Leituala Dr. Ben Matalavea and National Hospital cardiologist Asiata Dr Satupaitea Viali.

Authors from the Peter Doherty Institute for Infection and Immunity, Melbourne School of Population and Global Health, the Faculty of Medicine of the National University of Samoa, the University of Otago and the Southern District Health Board in New Zealand also contributed to the study.

They report that of the 833 children studied (428 males, 397 females and eight unspecified), 476 had impetigo observed on them, of which 263 infections were active.

Active impetigo was found in much higher rates in boys than in girls: 37.9 per cent versus 24.9 per cent. And across all infections, it was the same, with 65.2 per cent of boys showing infections compared to 48.6 per cent.

Younger children also had much higher rates than their older peers, with 42.3 per cent compared to 20.7 per cent. 

“There appears to be an acceptance of these conditions as ‘normal’ in Samoa, with 224 children self-reporting no impetigo despite having one or more impetigo lesions on observation,” the report authors said.

The study collected samples from 833 children from eight primary schools in the Falealili district, with both assessments and swabs studied by senior medical students at the National University of Samoa. 

Microbiological work was done at the National Hospital in Motootua, with swabs sent to the University of Melbourne’s Peter Doherty Institute for more study.

Across the eight schools studied, there was a wide range of results. As predicted, certain schools had high concentrations of disease. 

There were 36 many clusters (two or more children in a given location). Of the 36, 29 were limited to one school, while seven were identified between schools.

“Public health measures to disrupt ongoing transmission may have potential utility if introduced in schools,” the report suggests.

Interviews with the children sought to understand risk factors for the disease. According to the report, 70.8 per cent reported sharing a bedroom and 81.8 per cent reported sharing a bed. 

“Household size and sharing of bedding have also been reported as drivers of skin infections in other settings, and likely contribute to these infections in Samoa,” the report states. But with issues around data, these particular variables were not factored into the analysis model.

Impetigo is caused mostly by two bacteria, staphylococcus aureus and streptococcus pyogenes. In Samoa, antibiotic resistance to the safe and effective treatments is a major concern, with methicillin-resistant S. aureus (M.R.S.A.) identified in 24 impetigo cases (6.8 per cent) caused by staphylococcus aureas.

The researchers say the prevalence of scabies observed in Samoa is closer to that seen in other countries in the region. Of the 120 out of 833 children with scabies, a slight majority were boys, and most were between eight and 11 years old.

(Scabies may have been under-diagnosed, the authors warn).

Both skin diseases are contagious, with household crowding in tropical countries a major contributor to its spread.

They are both listed by the World Health Organisation as neglected topical diseases that need urgent attention, both in terms of treatment and research on the situation in each country where they persist.

“Neglected tropical diseases persist under conditions of poverty and are concentrated almost exclusively in impoverished populations in the developing world,” the W.H.O. says.

This study attempted to fill a marked gap in the epidemiological understanding of impetigo and scabies in the South Pacific, and undertook detailed genomic analysis of the samples it took.

It also makes recommendations based on its findings as to what can be done to clamp down on the spread of both diseases.

“Although impetigo and scabies are superficial infections, both conditions can be associated with severe complications,” the Samoan study explains.

Impetigo infections can progress into serious complications, including having infections enter the bones (osteomyelitis) or the blood (septicaemia) or develop into cellulitis.

“Our findings suggest a need for several public health measures,” the report concludes.

“These include improved health literacy related to skin infections like scabies and impetigo, including hygiene measures such as washing hands and covering open sores, and placing an emphasis on the need to air and sun bedding.

“Ongoing surveillance and management of impetigo and scabies in Samoa is recommended, supporting continued improvements to public health in this setting.”

Dr. George Taiaroa, Leituala Dr. Ben Matalavea, Dr. Malama Tafunai (Centre for Pacific Health, Division of Health Sciences, The University of Otago), Lupeoletalalelei Isaia, Hinauri Leaupepe, Asiata Dr. Satupaitea Viali (Ministry of Health), Professor Deborah Williamson (Peter Doherty Institute) and Dr. Susan Jack (University of Otago) conceived and designed the study.

The Ministry of Health has been approached for comment.

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