Rheumatic heart disease in school children in Samoa

Scabies prevalence after ivermectin-based mass drug administration for lymphatic filariasis, Samoa 2018-2019

BACKGROUND

Scabies is a common skin infestation caused by the Sarcoptes scabei mite. Ivermectin, one of three drugs used in mass drug administration (MDA) for lymphatic filariasis, is also effective for treating scabies. Ivermectin-based MDA was first conducted in Samoa in August 2018, with ivermectin being offered to those aged ≥5 years. Here, we report scabies prevalence in Samoa after MDA.

METHODS

We conducted household surveys 1.5-3.5 months (Survey 1) and 6-8 months (Survey 2) after the 2018 MDA in 35 primary sampling units. We conducted clinical examination for scabies-like rash and used International Alliance for the Control of Scabies classification criteria. We estimated scabies prevalence by age, gender and region. Multivariable logistic regression was used to assess factors associated with prevalence.

RESULTS

We surveyed 2868 people (499 households) and 2796 people (544 households) aged 0-75 years in Surveys 1 and 2, respectively. Scabies prevalence increased from 2.4% (95% CI 2.1-2.7%) to 4.4% (95% CI 4.0-4.9%) between surveys. Scabies was associated with younger age (0-4 years: aOR 3.5 [2.9-4.2]; 5-15 years: aOR 1.6 [1.4-1.8] compared to ≥16 years), female gender (aOR 1.2 [95% CI 1.1-1.4]; region (aOR range from 1.4 [1.1-1.7] to 2.5 [2.1-3.1] between regions), large households (aOR 2.6 [2.0-3.4] households ≥13), and not taking MDA in 2018 (aOR 1.3 [95% CI 1.1-1.6]).

CONCLUSIONS

We found moderate prevalence of scabies in two population-representative surveys conducted within 8 months of the 2018 MDA for lymphatic filariasis. Prevalence appeared to increase between the surveys, and ongoing surveillance is recommended, particularly in young children.

Scabies and impetigo in Samoa: A school-based clinical and molecular epidemiological study

Background

Common infections of the skin such as impetigo and scabies represent a large burden of disease globally, being particularly prevalent in tropical and resource-limited settings. Efforts to address these infections through mass drug administrations have recently been shown as efficacious and safe. In Samoa, a Pacific Island nation, there is a marked lack of epidemiological data for these neglected tropical diseases, or appreciation of their drivers in this setting.

Methods

An observational, cross-sectional survey of children aged between 4 and 15 years attending primary schools in rural areas of Upolu Island, Samoa was carried out to assess the prevalence of impetigo and scabies in schoolchildren residing in rural Samoa, integrated with descriptive epidemiological and microbial genomic data. A phylogenetic assessment of local Staphylococcus aureus isolated from Samoan schoolchildren was performed to estimate putative community transmission.

Findings

In this survey, the prevalence of impetigo observed in Samoan schoolchildren was one of the highest described globally (57•1%, 95% CI [53•8-60•5%], 476/833). Associations between active impetigo and age and gender were noted, with younger children and males more commonly affected (aOR2•8 [1•8-4•7]and aOR1•8 [1•3-2•5], respectively). The prevalence of scabies was similar to that seen in other South Pacific island countries (14•4%, 95% CI [12•2-17•0%], 120/833). Transmission of S. aureus was predicted, primarily between those children attending the same school. Carriage of S. pyogenes was notably low, with pharyngeal carriage observed in less than 2% of schoolchildren, consistent with earlier studies from Samoa.

Interpretation

This study describes a considerable burden of disease attributed to impetigo and scabies in Samoa. These findings will be valuable in addressing the public health challenge posed by these conditions, providing baseline prevalence data and highlighting practical strategies to reduce transmission of relevant microbes and parasites in this setting.

Tala Tomua

O a'afiaga o le pa'u i fa'ama'i o le po'u (impetigo) ma le utu o le pa'u (scabies), ua tele naua le fanau ua maua ai i le pasefika, ma le lalolagi atoa. O fuafuaga vaai mamao ma polokalame e fofoina ai nei faafitauli, e aofia ai le inumaga o fualaau e tapeina ai nei fa'ama'i, ua aliali mai ai e mafai ona faatamaia nei fa'ama'i. E le o tele ni tusitusiga ma faamaumauga i totonu o Samoa, pe ta'atele nei fa'amai o le pa'u pe leai. Ona o le le faatauaina o nei fa'ama'i, e le o iloa fo'i ni mafuaga ma nisi tulaga e faateleina ai nei fa'ama'i o le pa'u i Samoa.

Faatinoina o le suesuega

O le suesuega faasaenisi i le fanau aoga i le va o le 4 ma le 15 tausaga o loo ao'oga i le tulaga lua i nisi o nu'u i tua i Upolu, na faatinoina ai suesuega lea, ia suesueina ai le aotelega ma fainumera o le fanau ua maua i fa'ama'I o le po'u (impetigo) ma le utu o le pa'u (scabies). O lenei foi suesuega, na fia iloa ai fo'i po'o a ituaiga siama eseese o loo maua i luga o pa'u ma tino o le fanau aoga, ina ia iloa ai foi auala ua pipisi ai nei siama mai le isi tamaitiiti i le isi, ona mafua ai lea o nei fa'ama'i o le pa'u.

Tanuuga o le suesuega

Ua faailoa mai i le suesuega, le ta'atele o le fa'ama'i o le po'u (impetigo) ua maua ai le fanau aoga (57%), i aoga na faia ai le suesuega. O se fainumera ua maualuga tele i le lalolagi atoa. E toatele atu nisi o le fanau laiti (younger) ma tama (male) e maua i le po'u nai lo isi tamaiti. O le fainumera o le utu o le pa'u (scabies) (14·4%) e tai tutusa lava ma isi motu o le Pasefika. O le feaveaina o le siama faapitoa (staph aureus) ua tupu lea i le fanau ua ao'oga i le aoga e tasi. E le toatele foi nisi o le fanau (2%) na maua i le siama faapitoa o le fa'ai (strep pyogenes) e ona mafua ai le fiva rumatika. O lenei fainumera ua tai tutusa ma suesuega faasaenisi na fai muamua i Samoa.

Aotelega

O le aotelega la o lenei suesuega faasaenisi, ua faailoaina mai ai le tele naua o le fa'ama'i o le pa'u, o po'u (impetigo) ma le utu o le pa'u (scabies) i Samoa nei. O nei foi suesuega o le a aoga tele ini polokalame ma ni fuafuaga mamao e fa'afoisia ai nei faafitauli i le soifua maloloina o le fanau i Samoa. O le a avea foi nei fainumera e faamaumauina mo le silafia e le atunuu ma le soifua maloloina, le ta'atele o nei fa'amai o le pa'u, mo le tapenaina o ni fofo talafeagai ise taimi o i luma, ina ia faaitiitina ai le pipisi o nei siami i fanau ao'oga i Samoa.

The Global Epidemiology of Impetigo: A Systematic Review of the Population Prevalence of Impetigo and Pyoderma

Objective

We conducted a comprehensive, systematic review of the global childhood population prevalence of impetigo and the broader condition pyoderma.

Methods

PubMed was systematically searched for impetigo or pyoderma studies published between January 1 1970 and September 30 2014. Two independent reviewers extracted data from each relevant article on the prevalence of impetigo.

Findings

Sixty-six articles relating to 89 studies met our inclusion criteria. Based on population surveillance, 82 studies included data on 145,028 children assessed for pyoderma or impetigo. Median childhood prevalence was 12·3% (IQR 4·2–19·4%). Fifty-eight (65%) studies were from low or low-middle income countries, where median childhood prevalences were 8·4% (IQR 4·2–16·1%) and 14·5% (IQR 8·3–20·9%), respectively. However, the highest burden was seen in underprivileged children from marginalised communities of high-income countries; median prevalence 19·4%, (IQR 3·9–43·3%).

Conclusion

Based on data from studies published since 2000 from low and low-middle income countries, we estimate the global population of children suffering from impetigo at any one time to be in excess of 162 million, predominantly in tropical, resource-poor contexts. Impetigo is an under-recognised disease and in conjunction with scabies, comprises a major childhood dermatological condition with potential lifelong consequences if untreated.

Stroke Disparities: Disaggregating Native Hawaiians from other Pacific Islanders

OBJECTIVES

To compare the clinical characteristics of Native Hawaiians (NH) and other Pacific Islanders (PI) who are hospitalized with ischemic stroke.

DESIGN

Retrospective, cross-sectional analysis of medical records.

SETTING

Tertiary, Primary Stroke Center in Honolulu, Hawaii.

PATIENTS

Consecutive patients with race/ethnicity identified as NH or PI who were hospitalized for ischemic stroke between January 2006 and December 2012.

OUTCOME MEASURES

Age, sex, cardiovascular risk factors, intravenous tissue plasminogen activator (IV-tPA) utilization rate and hospital length of stay.

RESULTS

A total of 561 patients (57% NH and 43% PI) were studied. PI were younger (59 ± 13 years vs 62 ± 14 years, P = .002), had higher prevalence of diabetes mellitus (58% vs 41%, P < .0001) and prosthetic valve (6% vs 2%, P = .007), lower prevalence of smoking (14% vs 21%, P = .03), lower HDL cholesterol (38 ± 11 mg/dL vs 41 ± 13 mg/dL, P = .004), and higher discharge diastolic blood pressure (79 ± 15 vs 76 mm Hg ± 14 mm Hg, P = .04) compared to NH. No difference was seen in other cardiovascular risk factors. The IV-tPA utilization rate (5% vs 6%, P = .48) and the hospital length of stay (10 ± 17 days vs 10 ± 49 days, P = .86) were not different between the two groups.

CONCLUSION

Native Hawaiians and other Pacific Islanders with ischemic stroke have modestly different age of stroke presentation and burden of risk factors compared to each other. Disaggregating these two racial groups may be important to unmask any potential clinical differences in future studies.

Echocardiographic screening in a resource poor setting: borderline rheumatic heart disease could be a normal variant

OBJECTIVE

To estimate the echocardiography confirmed prevalence of rheumatic heart disease (RHD) in school children in Fiji.

DESIGN

Cross-sectional observational study.

SETTING

Ten primary schools in Fiji.

PATIENTS

School children aged 5-14 years.

INTERVENTIONS

Each child had an echocardiogram performed by an echocardiographic technician subsequently read by a paediatric cardiologist not involved with field screening, and auscultation performed by a paediatrician.

MAIN OUTCOME MEASURES

Echocardiographic criteria for RHD diagnosis were based on those previously published by the National Institutes of Health (NIH) and World Health Organization (WHO), and data were also analyzed using the new World Heart Federation (WHF) criteria. Prevalence figures were calculated with binomial 95% confidence intervals.

RESULTS

Using the modified NIH/WHO criteria the prevalence of definite RHD prevalence was 7.2 cases per 1000 (95% CI 3.7-12.5), and the prevalence of probable RHD 28.2 cases per 1000 (95% CI 20.8-37.3). By applying the WHF criteria the prevalence of definite and borderline RHD was 8.4 cases per 1000 (95% CI 4.6-14.1) and 10.8 cases per 1000 (95% CI 6.4-17.0) respectively. Definite RHD was more common in females (OR 5.1, 95% CI 1.1-48.3) and in children who attended school in a rural location (OR 2.3, 95% CI 0.6-13.50). Auscultation was poorly sensitive compared to echocardiography (30%).

CONCLUSION

There is a high burden of undiagnosed RHD in Fiji. Auscultation is poorly sensitive when compared to echocardiography in the detection of asymptomatic RHD. The results of this study highlight the importance of the use of highly sensitive and specific diagnostic criteria for echocardiography diagnosis of RHD.

World Heart Federation criteria for echocardiographic diagnosis of rheumatic heart disease--an evidence-based guideline

Over the past 5 years, the advent of echocardiographic screening for rheumatic heart disease (RHD) has revealed a higher RHD burden than previously thought. In light of this global experience, the development of new international echocardiographic guidelines that address the full spectrum of the rheumatic disease process is opportune. Systematic differences in the reporting of and diagnostic approach to RHD exist, reflecting differences in local experience and disease patterns. The World Heart Federation echocardiographic criteria for RHD have, therefore, been developed and are formulated on the basis of the best available evidence. Three categories are defined on the basis of assessment by 2D, continuous-wave, and color-Doppler echocardiography: 'definite RHD', 'borderline RHD', and 'normal'. Four subcategories of 'definite RHD' and three subcategories of 'borderline RHD' exist, to reflect the various disease patterns. The morphological features of RHD and the criteria for pathological mitral and aortic regurgitation are also defined. The criteria are modified for those aged over 20 years on the basis of the available evidence. The standardized criteria aim to permit rapid and consistent identification of individuals with RHD without a clear history of acute rheumatic fever and hence allow enrollment into secondary prophylaxis programs. However, important unanswered questions remain about the importance of subclinical disease (borderline or definite RHD on echocardiography without a clinical pathological murmur), and about the practicalities of implementing screening programs. These standardized criteria will help enable new studies to be designed to evaluate the role of echocardiographic screening in RHD control.

Group a streptococcal diseases and their global burden

Group A streptococcus (GAS) or Streptococcus pyogenes has been recognised as an important human pathogen since early days of modern microbiology, and it remains among the top ten causes of mortality from an infectious disease. Clinical manifestations attributable to this organism are perhaps the most diverse of any single human pathogen. These encompass invasive GAS infections, with high mortality rates despite effective antimicrobials, toxin-mediated diseases including scarlet fever and streptococcal toxic shock syndrome, the autoimmune sequelae of rheumatic fever and glomerulonephritis with potential for long-term disability, and nuisance manifestations of superficial skin and pharyngeal infection, which continue to consume a sizable proportion of healthcare resources. Although an historical perspective indicates major overall reductions in GAS infection rates in the modern era, chiefly as a result of widespread improvements in socioeconomic circumstances, this pathogen remains as a leading infectious cause of global morbidity and mortality. More than 18 million people globally are estimated to suffer from serious GAS disease. This burden disproportionally affects least affluent populations, and is a major cause of illness and death among children and young adults, including pregnant women, in low-resource settings. We review GAS transmission characteristics and prevention strategies, historical and geographical trends and report on the estimated global burden disease attributable to GAS. The lack of systematic reporting makes accurate estimation of rates difficult. This highlights the need to support improved surveillance and epidemiological research in low-resource settings, in order to enable better assessment of national and global disease burdens, target control strategies appropriately and assess the success of control interventions.

Rheumatic heart disease and its control in the Pacific

Rheumatic fever and rheumatic heart disease continue to be a huge public-health burden on many Pacific Island countries. Prevalence reported in some nations are some of the highest seen globally, yet many countries in the region do not have national disease registers. Despite the will of many Pacific Island countries, there are a number of barriers to the implementation and sustainability of effective coordinated prevention programs, including limited funding and competing health priorities. In promising recent developments, a number of countries in the region have been able to develop or strengthen national rheumatic heart disease registers. These registers allow for more effective delivery of secondary prophylaxis, the mainstay of disease control in the Pacific. Primary prevention of rheumatic fever and screening for rheumatic heart disease are important adjunctive strategies. Recent advances in screening methods, focusing on portable echocardiography, may allow for the early detection of rheumatic heart disease in the community.

The persistent challenge of rheumatic fever in the Northern Mariana Islands

OBJECTIVES

Acute rheumatic fever (ARF) is a major cause of morbidity and mortality in developing nations. The objective of this study was to determine the disease burden of ARF among the indigenous and non-indigenous populations of the Northern Mariana Islands.

METHODS

This was a chart review of all pediatric outpatients seen from 1984 to 2006 with ICD-9 codes corresponding to rheumatic fever or any rheumatic cardiac sequelae. The study was set in the only comprehensive inpatient facility and only public pediatric clinic in the Northern Mariana Islands.

RESULTS

One hundred fifty-eight cases of ARF were identified. Age at diagnosis ranged from 2.9 to 17.1 years (median 10.6 years). Fever and carditis were the most common presenting findings. The average annualized incidence of ARF was 85.8 per 100,000 person-years for those aged 5-14 years. Sixty-six percent of patients with ARF were of Chamorro or Carolinian ancestry, despite comprising only 39% of the total population, with a combined average annualized incidence of ARF of 167 per 100,000 person-years.

CONCLUSIONS

This is the first documentation of the incidence of pediatric ARF in the Northern Mariana Islands, delineating the large disease burden in the indigenous and other Pacific Island ethnic groups. Impediments to diagnosis and primary and secondary prevention were identified. The data provide strong support for the need for primary and secondary prevention of ARF.

Higher rates of streptococcal colonization among children in the Pacific Rim Region correlates with higher rates of group A streptococcal disease and sequelae

Group A streptococcal (GAS) pharyngeal colonization rates were determined among 1061 asymptomatic students in Hawaii and American Samoa where acute rheumatic fever rates are high. All GAS isolates were emm sequence typed. Although pharyngeal colonization rates were low in Hawaii (3.4%), Pacific Islander children had significantly higher colonization rates (5.7% vs. 1.2% in other ethnic groups, p <0.05). The colonization rate was higher in American Samoa (13%). Few emm types that were infrequently observed in symptomatic infections in Hawaii were repeatedly identified in both sites. These emm types were previously described among asymptomatic children suggesting a type-specific association with pharyngeal colonization.

High burden of impetigo and scabies in a tropical country

Background

Impetigo and scabies are endemic diseases in many tropical countries; however the epidemiology of these diseases is poorly understood in many areas, particularly in the Pacific.

Methodology/Principal Findings

We conducted three epidemiological studies in 2006 and 2007 to determine the burden of disease due to impetigo and scabies in children in Fiji using simple and easily reproducible methodology. Two studies were performed in primary school children (one study was a cross-sectional study and the other a prospective cohort study over ten months) and one study was performed in infants (cross-sectional). The prevalence of active impetigo was 25.6% (95% CI 24.1–27.1) in primary school children and 12.2% (95% CI 9.3–15.6) in infants. The prevalence of scabies was 18.5% (95% CI 17.2–19.8) in primary school children and 14.0% (95% CI 10.8–17.2) in infants. The incidence density of active impetigo, group A streptococcal (GAS) impetigo, Staphylococcus aureus impetigo and scabies was 122, 80, 64 and 51 cases per 100 child-years respectively. Impetigo was strongly associated with scabies infestation (odds ratio, OR, 2.4, 95% CI 1.6–3.7) and was more common in Indigenous Fijian children when compared with children of other ethnicities (OR 3.6, 95% CI 2.7–4.7). The majority of cases of active impetigo in the children in our study were caused by GAS. S. aureus was also a common cause (57.4% in school aged children and 69% in infants).

Conclusions/Significance

These data suggest that the impetigo and scabies disease burden in children in Fiji has been underestimated, and possibly other tropical developing countries in the Pacific. These diseases are more than benign nuisance diseases and consideration needs to be given to expanded public health initiatives to improve their control.

Scabies and impetigo are often thought of as nuisance diseases, but have the potential to cause a great deal of morbidity and even mortality if infection becomes complicated. Accurate assessments of these diseases are lacking, particularly in tropical developing countries. We performed a series of studies in infants and primary school children in Fiji, a tropical developing country in the South Pacific. Impetigo was very common: more than a quarter of school-aged children and 12% of infants had active impetigo. Scabies was also very common affecting 18% of school children and 14% of infants. The group A streptococcus was the most common infective organism followed by Staphylococcus aureus. The size of the problem has been underestimated, particularly in the Pacific. It is time for more concerted public health efforts in controlling impetigo and scabies.

Acute rheumatic fever in American Samoa

Acute rheumatic fever is common among Samoans in Hawaii. During 2 visits to evaluate the magnitude of rheumatic fever problem among Samoans in American Samoa, we identified 148 patients with rheumatic fever on penicillin prophylaxis. Retrospective chart reviews were done showing possible delays in diagnosis of acute rheumatic fever.

Group A streptococcal infections in children

The group A streptococcus causes the widest range of disease in humans of all bacterial pathogens. Group A streptococcal diseases are more common in children than adults with diseases ranging from pharyngitis and impetigo to invasive infections and the post-streptococcal sequelae--acute rheumatic fever and acute post-streptococcal glomerulonephritis. The global burden of severe group A streptococcal disease is concentrated largely in developing countries and Indigenous populations such as Aboriginal Australians. Control of group A streptococcal disease is poor in these settings and the need for a vaccine has been argued. With an ever-increasing understanding of the group A streptococcus at a molecular level, new and sophisticated vaccines are currently in human trials and the next decade holds exciting prospects for curbing group A streptococcal diseases.

Ethnic differences for developing rheumatic fever in a low-income group living in Hawaii

The risk factors responsible for acute rheumatic fever (ARF) are complex, in part, because group A streptococcus (GAS) infection is a prerequisite for this disease. We attempted to differentiate socioeconomic from genetic risk factors by studying subjects in a Hawaii pediatric cardiology clinic who qualified for Medicaid. This ethnically diverse group was unique because they maintained a low socioeconomic but generally healthy lifestyle with more limited risks than those living in extremely impoverished conditions.

METHODS

Questionnaires were administered to consenting subjects in the clinic, who were divided into those diagnosed with ARF (n = 26) and those with other (primarily congenital) heart diseases (n = 41).

RESULTS

The socioeconomic status of the ARF and non-ARF groups was lower than that of the Hawaii population in general, and little differences were noted between the groups. The ARF group, however, had slightly larger household sizes and more children than the non-ARF group. The greatest difference was in ethnicity. By the Fisher exact test, the number of Polynesians belonging to the ARF group was significantly greater than all other ethnicities (P = .005). Polynesians had an odds ratio > 4.80 of developing ARF, which increased to 6.33 when number of children per household was considered.

CONCLUSION

The potential contribution of genetic predisposing factors for developing ARF was analyzed in subjects living in a homogeneously low socioeconomic level relative to the general Hawaii population. Polynesians were at highest risk when compared to other ethnicities living in similar socioeconomic conditions.

Acute rheumatic fever

Acute rheumatic fever (ARF) and its chronic sequela, rheumatic heart disease (RHD), have become rare in most affluent populations, but remain unchecked in developing countries and in some poor, mainly indigenous populations in wealthy countries. More than a century of research, mainly in North America and Europe, has improved our understanding of ARF and RHD. However, whether traditional views need to be updated in view of the epidemiological shift of the past 50 years is still to be established, and improved data from developing countries are needed. Doctors who work in populations with a high incidence of ARF are adapting existing diagnostic guidelines to increase their sensitivity. Group A streptococcal vaccines are still years away from being available and, even if the obstacles of serotype coverage and safety can be overcome, their cost could make them inaccessible to the populations that need them most. New approaches to primary prevention are needed given the limitations of primary prophylaxis as a population-based strategy. The most effective approach for control of ARF and RHD is secondary prophylaxis, which is best delivered as part of a coordinated control programme.

Spread of heart diseases seen in an open-access paediatric echocardiography clinic

All patients <13 years of age referred to the open-access paediatric echocardiography clinic at the Sultan Qaboos University Hospital, Muscat, Oman, during the five years from 1994 to 1998 were analysed. Among the 2633 patients studied, 1543 (58.6%) were normal, 845 (32.1%) had congenital heart disease, and 245 (9.3%) had acquired heart disease. The major congenital heart diseases identified were secundum atrial septal defect (22.5%), ventricular septal defect (22.5%), patent ductus arteriosus (15.7%), mitral valve prolapse (10.7%), pulmonary stenosis (9.7%) and atrioventricular septal defect (4.5%). Fifty-eight percent of the congenital heart diseases were identified in the first year of life. Among the acquired heart diseases, rheumatic heart disease (30.2%) and cardiac involvement secondary to haemoglobinopathies (16.7%), dilated cardiomyopathy (16.3%) and hypertrophic cardiomyopathy (12.7%) were significant. Although the presence of specific cardiac symptoms was associated with a high yield of abnormalities, such disorders were also discovered in a significant number of children with isolated cardiac murmur. The referral source did not influence significantly the frequency of heart diseases diagnosed in this study. Open-access echocardiography is important in early detection of heart disease in the paediatric population.

Systematic review of rheumatic heart disease prevalence in children in developing countries: the role of environmental factors

OBJECTIVES

To consider the worldwide prevalence of rheumatic heart disease in children in developing countries using surveys with uniform methodologies, and to consider the effect of environmental factors including socio-economic status, overcrowding, urbanization, nutrition and access to medical services on the distribution of rheumatic heart disease in developing countries.

METHODS

Sixty-one surveys of the prevalence of rheumatic heart disease in developing countries were found using a systematic review of MEDLINE from January 1976 to July 1999. Twenty-four studies were selected for comparison based on their uniform methodological and diagnostic techniques.

RESULTS

There is a high prevalence of rheumatic heart disease in the Pacific region with a lower prevalence in the Indian subcontinent, Asian, sub-Saharan African, Mediterranean, Latin American and Caribbean regions. However, aside from the Indian subcontinent, these regions have not been well studied, and it may be that the true prevalence is actually higher.

CONCLUSIONS

There is a lack of good quality prevalence surveys of rheumatic heart disease in developing countries. It appears that a threshold level where higher socio-economic status is associated with reduced prevalence of rheumatic heart disease is not reached in developing countries. Therefore, differences in prevalence between socio-economic groups in the one area cannot be detected. A similar case can be made for overcrowding. Many regions need well-designed studies of rheumatic heart disease that incorporate assessment of environmental factors as well as the study of the microbiological epidemiology of rheumatic heart disease and group A streptococci.