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| Journal of the New Zealand Medical Association,
03-June-2005, Vol 118 No 1216
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Soil-transmitted helminth infection, skin infection, anaemia,
and growth retardation in schoolchildren of Taveuni Island, Fiji
Mark Thomas, Graeme Woodfield, Christine Moses, Geoffrey
Amos
Anaemia due to hookworm infection and impetigo secondary to
scabies are reported to be common problems in Fijian
children.1–3 Both hookworm infection and
scabies are amenable to community-based control programs which can provide
significant long-term benefits for childhood
health.4–7
The World Health Organization (WHO) has drawn attention to
the morbidity and mortality caused by soil-transmitted helminths (i.e. the
hookworms Necator americanus and
Ancylostoma duodenale, and the
nematodes Ascaris lumbricoides and
Trichuris trichiura). It has been
estimated that the burden of disease caused by soil-transmitted helminth (STH)
infection in school-age children in developing countries is greater than that
caused by any other communicable or non-communicable disease.
In response to this problem, the WHO has recommended that
school-based programs to control STH infections should be instituted if the
cumulative prevalence of STH infection in schoolchildren is greater than
50%.8
Prompted by local concern about the impact of hookworm and
scabies on the health of the children of Taveuni Island, we sought to estimate
the prevalence of STH infection, anaemia, scabies, impetigo, and growth
retardation in a representative sample of schoolchildren aged 5 to 15 years on
Taveuni Island, Fiji.
MethodsWe based our survey on WHO
guidelines for school-based surveys.8 Children
were recruited at five geographically separated schools during the second week
of June 2004. After obtaining informed written consent from their parents, the
children had their height and weight measured, their hands, arms, legs, and feet
examined for scabies and impetigo, and the haemoglobin concentration estimated
on a finger-prick sample of their blood, using a portable haemoglobinometer
(HemoCue, Sheffield, England).
All children were provided with a specimen jar
containing 7 ml of 40% formalinised saline, and were asked to return this jar to
school, the following day, with a small sample of their faeces. These faeces
samples were refrigerated until examined at Diagnostic Medlab, Auckland, for the
presence of helminth ova using the formal ethyl acetate concentration
method.
All children were treated with a single 400 mg oral
dose of albendazole (Eskazole, SKB) and those with anaemia (haemoglobin [Hb]
level <110g/L) were treated with ferrous sulphate (Ferrogradumet, Abbott) 325
mg daily for 3 months.
Children with scabies or impetigo were treated with
permethrin cream (Lyderm, PSM Healthcare Ltd) or mupirocin ointment (Bactroban,
GSK) respectively. Nurses with responsibility for the communities served by each
of the schools assisted with the evaluation of each child, gave advice to the
child and their parents on the medical treatments provided, and arranged
follow-up care as necessary.
Children whose height or weight was less than or equal
to the third centile for children of their age and sex (2000 CDC growth charts,
National Center for Health Statistics)9 were
defined as suffering from growth retardation.
Scabies infection was diagnosed in children with
typical papules and a history of itch, and was graded as 1+ (<10 papules), 2+
(10–20 papules), or 3+ (>20 papules). Impetigo was diagnosed in
children with superficial vesicular or crusted skin lesions and was graded as 1+
(1-2 lesions), 2+ (3-5 lesions), or 3+ (>5 lesions).
Differences in categorical variables across groups were
compared using Fisher’s Exact test, and an unpaired t-test was used to
compare continuous variables. All analyses were performed using SAS statistical
software.
The study was approved by the Fiji Department of Health
Ethics Committee.
ResultsA total of 258 children, aged
between 5 and 15 years and from five schools, participated in the survey
(Table1).
206 children (80% of the total sample) provided a faecal
sample for subsequent examination for helminth ova. The overall prevalence of
STH infection was 45% (95% CI: 38–52%). Hookworm (14%),
ascaris (33%), and
trichuris (17%) were commonly detected
(Table 1).
The prevalence of hookworm infection did not differ greatly
between villages. In contrast, however, the prevalence of
ascaris and trichuris did differ
between villages (Figure 1). Overall, 39/50 (78%) of children from Waimakilu
village had a STH infection, compared with 8/41 (20%) of children from Niusawa
village; p <0.001. Three children, one each from Bouma, Wainikeli, and
Niusawa villages, had Strongyloides
stercoralis ova in their faecal samples.
250 children (97% of the total sample) provided a finger
prick sample of blood. The haemoglobin concentration in these samples ranged
from 71–149 g/L (mean=125, SD=11) (Figure 2).
Nineteen children (8%) had a haemoglobin concentration less
than 110 g/L. Four out of 29 (14%) children with hookworm infection were
anaemic, compared with 8/177 children who did not have hookworm infection (RR:
3.4, 95% CI: 0.95–11.4, p=0.07) (Table 2).
234 children (91% of the total sample) had their height and
weight measured. The distribution of heights and weights of these children are
shown in Figure 3. Overall, the distribution of the children’s heights
corresponded with the range found in children in the United States, although the
distribution of heights for the older boys was less than expected. The
distribution of weights of both the boys and the girls was lower than predicted
at all age ranges. A total of 19 children (13 boys and 6 girls) were on or below
the third centile of their expected weight for age, and a total of 14 children
(9 boys and 5 girls) were on or below the third centile of their expected height
for age.
There were no significant differences in the prevalence of
growth retardation either between children with or without hookworm infection,
or between children with or without any STH infection.
All 258 children were examined for the presence of scabies
and impetigo; 84 (32%) children had scabies (which was graded as 1+ in 48
children, 2+ in 26 children, and 3+ in 10 children) but no child had crusted
scabies.
The prevalence of scabies in children from each of the five
schools is shown in Figure 4. Six children (2%) had impetigo, which was graded
as 1+ in all six children. Two children in Waimakilu village school, and one
child in each of the other schools, had impetigo.
DiscussionThis study is the largest survey to
date of the relationships between STH infection and anaemia and growth
retardation in Fijian children. We are not aware of any recent comparable data
from other regions of Fiji and therefore cannot exclude the possibility that our
results are not broadly representative of all Fijian schoolchildren.
We did, however, make a concerted effort to recruit students
across a broad age range, from widely separated schools, and within communities
with differing levels of infrastructure development. As a result, we are
confident that our results are representative of the approximately 3,500
children who attend the 21 schools on Taveuni, the third-largest island of the
Fiji Islands group in terms of land area.
We found a striking disparity in the prevalence of STH
infection between schoolchildren from different villages on Taveuni. In one
village, Waimakilu, the cumulative prevalence of STH infection in schoolchildren
was almost 80%, while in two other villages, Niusawa and Vuna, the prevalence
was only 20% and 25% respectively.
These differences in the cumulative prevalence of STH
infection between villages have important implications for the design of
helminth control programs. In communities where the cumulative prevalence of STH
infection in school-age children exceeds 70%, the WHO recommends that all
school-age children should be treated for STH infection 2–3 times per
year.
In contrast, in communities where the cumulative prevalence
of STH infection in school-age children is 50–70%, the WHO recommends that
all school-age children should be treated for STH infection at least once a
year. The WHO does not recommend regular treatment of STH infection if the
cumulative prevalence of STH infection in school-age children is <50%. Health
education and improvements in sanitation and water supply are recommended for
all communities, but especially those communities with a very high prevalence of
STH infection.8
We found that the prevalence of hookworm infection was less
than that reported by others. Hawley surveyed two communities on Viti Levu
Island in 1968 and 1969, and found that the prevalence of hookworm infection was
11% in children aged less than 1 year, 38% in children aged 1–5 years, 87%
in children aged 6–10 years and 90% in children aged 11–15
years.2 Mathai et al surveyed two communities
on Viti Levu Island during the 1990s and found hookworm infection in 19% of
schoolchildren in one community and 50% of subjects of all ages in another
community.1
Similar high rates of infection were found in an isolated
Aboriginal community in northern Australia where 93% of children aged 5–14
years were infected;4 in children in the
Muheza, Tanga, and Korogwe districts of Tanzania where 61% of children were
infected;5 and in primary schoolchildren in
KwaZulu-Natal, South Africa, where 59% of children were
infected.6 The prevalence of hookworm infection
in the schoolchildren of Taveuni is much less than the prevalence in other
countries where school-based anthelminthic programs have been
instituted.3–5
We found that 8% of children were anaemic (Hb <110 g/L).
Buchanan et al surveyed a large number of children for anaemia in four regions
of Viti Levu Island in 1975.10 Buchanan et al
found that 33/890 (3.7%) of children aged 5–9 years were anaemic (packed
cell volume [PCV] <0.33), and that 162/690(23.5%) of children aged
10–14 years were anaemic (PCV <0.37).
Our results cannot be directly compared with those of
Buchanan et al, however, because we used different criteria for the diagnosis of
anaemia. Our results are broadly similar, however, and suggest that anaemia is
not a common health problem for schoolchildren on Taveuni.
The association of anaemia with hookworm infection in our
survey suggests that either testing for hookworm infection and treatment of
those found to be infected, or empiric treatment of hookworm, should be routine
for children with anaemia. However the relatively low prevalence of hookworm
infection in our study suggests that community-wide treatment of hookworm would
provide only modest benefits in terms of prevention of anaemia.
There are few data available on the height and weight of
schoolchildren in Fiji.11,12 Our results
provide a useful overview of the height and weight of schoolchildren on Taveuni.
We found that significant growth retardation was not common in schoolchildren on
Taveuni. The overall distribution of heights for boys and girls corresponded
well with the distribution predicted by the 2000 CDC growth charts, which are
based on surveys of US children.9 However the
overall distribution of weights for both boys and girls was lower than the
distribution predicted by the 2000 CDC growth charts; 19/234(8%) children
weighed less than the third centile for their age and 14/234(6%) children were
shorter than the third centile for their age.
There was no association between village of residence, the
presence of hookworm infection or the presence of any STH infection and growth
retardation. This suggests that school-based anthelminthic programs would not
have a significant effect on either the height or weight of Taveuni
schoolchildren.
We found that scabies was common but was not associated with
a high prevalence of impetigo. The two villages with the highest prevalence of
scabies, Waimakilu and Bouma, were the villages which also had the highest
cumulative prevalence of STH infection. This suggests that the same
environmental factors may contribute to the persistence of these infections. We
noted that the water supply was less well-developed in Waimakilu and Bouma than
in the other three villages and expect that improvements in water supply to
these and similar villages would confer diverse health benefits.
In conclusion we found a relatively low prevalence of
hookworm infection, anaemia, and growth retardation in Taveuni Island
schoolchildren. These results suggest that repeated, school-based, anthelminthic
programs directed primarily against hookworm would confer marginal health
benefits. We did, however, find moderately high cumulative prevalence of other
STH infections which might benefit from repeated, school-based, anthelminthic
programs directed primarily against ascaris and trichuris.
Alternatively, efforts to improve water supply and
sanitation might achieve similar reductions in hookworm and other STH
prevalence, with the additional benefit of reductions in the prevalence of other
infectious diseases such as skin and gastrointestinal infections. We found a
moderately high prevalence of scabies and a surprisingly low prevalence of
impetigo. Improvements in water supply and improved case finding and treatment
may be expected to reduce the prevalence of scabies.
Our measurements of height and weight and haemoglobin
concentration provide data which should be compared with those from other Fiji
or Pacific communities. They should stimulate research to determine the reasons
for the children of Taveuni Island to generally weigh less than expected for
their age.
Author information:
Mark Thomas, Associate Professor of Infectious Diseases; Graeme Woodfield,
Associate Professor of Haematology, Department of Molecular Medicine and
Pathology, Faculty of Medical and Health Sciences, University of Auckland,
Auckland; Christine Moses, Purchasing and Facilities Manager, Diagnostic Medlab,
Auckand; Geoffrey Amos, Immediate Past President, Rotary Club of Taveuni,
Taveuni, Fiji.
Acknowledgements:
This study was generously supported by the Rotary Clubs in Taveuni (Fiji), Kumeu
(New Zealand), and Newmarket (New Zealand). Diagnostic Medlab (Auckland, New
Zealand) kindly examined the faecal samples for helminth ova and provided some
of the equipment used in the project. The nurses and teachers who serve the
community of Taveuni; as well as Mimi Irwin, Kelvin Moses, and Annabell
Woodfield; assisted greatly with the examination of the children.
Teena West kindly provided statistical assistance.
Correspondence:
Associate Professor Mark Thomas, Department of Molecular Medicine and Pathology,
Faculty of Medical and Health Sciences, University of Auckland, Private Bag
92019, Auckland. Fax: (09) 373 7492; email: mg.thomas@auckland.ac.nz
References:
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