An epidemiological study of rheumatic fever and rheumatic heart disease in Lagos

Streptococcal Throat Carriage among Primary School Children Living in Uyo, Southern Nigeria

Surveillance of the carrier state for β-hemolytic streptococcal (BHS) throat infections remains essential for disease control. Recent published works from Sub-Saharan Africa have suggested a changing epidemiology in the burden of BHS throat infections. The objective of the present study was therefore to determine the prevalence and pattern of BHS throat carriage in school-aged children in Uyo, Akwa Ibom State. This was a prospective cross-sectional study of 276 primary school children in Uyo. Subjects were recruited by multistage random sampling. Obtained throat swabs were cultured on 5% sheep blood agar. Lancefield grouping on positive cultures was done by using the Oxoid Streptococcal Grouping Latex Agglutination Kit, United Kingdom. Antimicrobial susceptibility testing was done with the disk diffusion method. Associations were tested with Fischer's exact test. The prevalence of BHS carriage was 3.3%. Group C Streptococcus was identified in 89% of isolates and Group G Streptococcus in 11%. Younger age and larger household size were associated with asymptomatic streptococcal throat infections. Antimicrobial susceptibility was highest with cefuroxime and clindamycin (89% of isolates each), while 78% of isolates were susceptible to penicillin. None of the tested isolates was susceptible to co-trimoxazole. The prevalence of streptococcal throat carriage in the study area was low. There were no Group A Streptococcus isolates suggesting an evolving epidemiology of BHS disease in the study area.

Prevalence of rheumatic heart disease in North-Central Nigeria: a school-based cross-sectional pilot study

OBJECTIVES

To present epidemiological data on rheumatic heart disease (RHD), the most common acquired heart disease in children and young adults in low- and middle-income countries, for North-Central Nigeria.

METHODS

In this pilot study, we conducted clinical and echocardiography screening on a cross section of randomly selected secondary schoolchildren in Jos, North-Central Nigeria, from March to September 2016. For outcome classification into borderline or definite RHD, we performed a confirmatory echocardiography using the World Heart Federation criteria for those suspected to have RHD from the screening.

RESULTS

A total of 417 secondary schoolchildren were screened, of whom 247 (59.2%) were female. The median age was 14 years (IQR: 13-15). Clinical screening detected 8/417 children, whereas screening echocardiography detected 42/417 suspected cases of RHD. Definitive echocardiography confirmed 9/417 with RHD corresponding to a prevalence of 21.6 per 1000 (95% CI, 6.7-36.5). All but one of the confirmed RHD cases (8/9) were borderline RHD corresponding to a prevalence of 19.2 per 1000 (95% CI, 8.3-37.5) for borderline RHD and 2.4 per 1000 (95% CI, 0.1-13.3) for definite RHD. RHD was more common in boys and cardiac auscultation missed over 50% of the cases.

CONCLUSIONS

This study showed a high prevalence of RHD among secondary schoolchildren in North-Central Nigeria with a vast predominance of asymptomatic borderline lesions. Larger school-based echocardiography screening using portable or handheld echocardiography aimed at early detection of subclinical RHD should be adopted.

Echocardiographic screening of 4107 Nigerian school children for rheumatic heart disease

OBJECTIVE

Echocardiographic screening for Rheumatic Heart Disease (RHD) in Africa has revealed prevalence rates in the range of 0.5-7.4%. There are no recent large population-based studies in Nigeria. The objective of the study was to determine the prevalence of RHD in a large sample of Nigerian school children.

METHODS

Using portable transthoracic echocardiography and auscultation, school children aged 5 years to 16 years in Lagos, Nigeria were screened for RHD. Diagnosis was based on the 2012 World Heart Federation echocardiographic criteria.

RESULTS

The 4107 children screened had mean age of 11.3 years (SD = 2.6) and 2206 (53.7%) were females. There were 38 children with abnormal echocardiograms, of which 11 (0.27%) showed RHD including two cases of definite RHD giving a prevalence of 2.7/1000 [2.9/1000 in the peri-urban, 2.4/1000 in the urban area). Echocardiography detected RHD 10 times better than auscultation [echocardiography 11 (0.27%) vs. auscultation 1 (0.02%); P = 0.003]. The remaining 27 children with abnormal echocardiograms had congenital heart defects (CHD) giving a prevalence of 6.6/1000 for CHD, a yield higher than for RHD.

CONCLUSION

Prevalence of RHD among school children in Lagos, South West Nigeria is low compared to other African countries, possibly due to better access to medical care and antibiotic treatment for infections. Our data provides evidence that RHD prevalence may vary substantially within sub-Saharan Africa, necessitating targeted population-based sampling to better understand disease burden and distribution. Further work is needed to compare within- and between-country RHD prevalence as a basis for programme planning and control efforts.

Small plasmids in Streptococcus dysgalactiae subsp. equisimilis isolated from human infections in southern India and sequence analysis of two novel plasmids

Small plasmids are frequently found in S. pyogenes isolates from human infections in India. Streptococcus dysgalactiae subsp. equisimilis (SDSE) is a streptococcal subspecies that is genetically similar to S. pyogenes and has a similar ecology. Therefore, we determined the distribution of small plasmids in a collection of 254 SDSE isolates, comprising 44 different emm-types and emm non-typable strains, from southern India, utilizing an established PCR based method. Briefly, 1.2% (n=3) of the isolates were positive for repA (encoding the replication initiation protein A) and 1.6% (n=4) were repB positive (encoding the replication initiation protein B). One isolate (G315) showed a co-detection of repB and dysA (encoding the bacteriocin dysgalacticin) which is characteristic for previously described pDN281/pW2580-like plasmids, observed in SDSE and S. pyogenes. The remaining plasmid bearing isolates showed no characteristic co-detection of known plasmid-associated genes. Thus, plasmids pG271 and pG279, representatives for repB and repA harboring plasmids, respectively, were analyzed. The plasmids pG271 and pG279 could be assigned to the pMV158 and the pC194/pUB110 family of rolling-circle plasmids, respectively. Like the characterized small native plasmids of S. pyogenes from India, the SDSE plasmids discovered and described in this study did not carry any of the known antibiotic resistance genes. SDSE bore less of the investigated small native plasmids that were distinct from the small native plasmids of S. pyogenes of the same geographic region. This indicates a low rate of lateral transfer of these genetic elements between these two related streptococcal species.

Estimating rheumatic fever incidence in New Zealand using multiple data sources

Rheumatic fever (RF) is an important public health problem in New Zealand (NZ). There are three sources of RF surveillance data, all with major limitations that prevent NZ generating accurate epidemiological information. We aimed to estimate the likely RF incidence using multiple surveillance data sources. National RF hospitalization and notification data were obtained, covering the periods 1988-2011 and 1997-2011, respectively. Data were also obtained from four regional registers: Wellington, Waikato, Hawke's Bay and Rotorua. Coded patient identifiers were used to calculate the proportion of individuals who could be matched between datasets. Capture-recapture analyses were used to calculate the likely number of true RF cases for the period 1997-2011. A range of scenarios were used to correct for likely dataset incompleteness. The estimated sensitivity of each data source was calculated. Patients who were male, Māori or Pacific, aged 5-15 years and met the Jones criteria, were most likely to be matched between national datasets. All registers appeared incomplete. An average of 113 new initial cases occurred annually. Sensitivity was estimated at 80% for the hospitalization dataset and 60% for the notification dataset. There is a clear need to develop a high-quality RF surveillance system, such as a national register. Such a system could link important data sources to provide effective, comprehensive national surveillance to support both strategy-focused and control-focused activities, helping reduce the incidence and impact of this disease. It is important to remind clinicians that RF cases do occur outside the well-characterized high-risk group.

Host-pathogen interactions in streptococcal immune sequelae

Otherwise uncomplicated infections with Streptococcus pyogenes can cause two insidious immune sequelae known as post-streptococcal glomerulonephritis (PSGN) and acute rheumatic fever (ARF). These diseases follow with a latency of a few weeks or months after primary infection and are responsible for high mortality and morbidity. PSGN has also been linked to infections with group C streptococci of the species S. equi ssp. zooepidemicus (SESZ). Moreover, there are some indications that infection with group C and G streptococci (GCGS) of the subspecies Streptococcus dysgalactiae ssp. equisimilis (SDSE) leads to ARF. Despite decades of research, the picture of the molecular pathogenesis of streptococcal immune sequelae resembles a jigsaw puzzle. Herein we try to put some of the puzzle bits together that have been collected till date.

Non-communicable diseases in sub-Saharan Africa: what we know now

BACKGROUND

Sub-Saharan Africa (SSA) has a disproportionate burden of both infectious and chronic diseases compared with other world regions. Current disease estimates for SSA are based on sparse data, but projections indicate increases in non-communicable diseases (NCDs) caused by demographic and epidemiologic transitions. We review the literature on NCDs in SSA and summarize data from the World Health Organization and International Agency for Research on Cancer on the prevalence and incidence of cardiovascular diseases, diabetes mellitus Type 2, cancer and their risk factors.

METHODS

We searched the PubMed database for studies on each condition, and included those that were community based, conducted in any SSA country and reported on disease or risk factor prevalence, incidence or mortality.

RESULTS

We found few community-based studies and some countries (such as South Africa) were over-represented. The prevalence of NCDs and risk factors varied considerably between countries, urban/rural location and other sub-populations. The prevalence of stroke ranged from 0.07 to 0.3%, diabetes mellitus from 0 to 16%, hypertension from 6 to 48%, obesity from 0.4 to 43% and current smoking from 0.4 to 71%. Hypertension prevalence was consistently similar among men and women, whereas women were more frequently obese and men were more frequently current smokers.

CONCLUSIONS

The prevalence of NCDs and their risk factors is high in some SSA settings. With the lack of vital statistics systems, epidemiologic studies with a variety of designs (cross-sectional, longitudinal and interventional) capable of in-depth analyses of risk factors could provide a better understanding of NCDs in SSA, and inform health-care policy to mitigate the oncoming NCD epidemic.

The worldwide epidemiology of acute rheumatic fever and rheumatic heart disease

Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) are significant public health concerns around the world. Despite decreasing incidence, there is still a significant disease burden, especially in developing nations. This review provides background on the history of ARF, its pathology and treatment, and the current reported worldwide incidence of ARF and prevalence of RHD.

Prospective surveillance of streptococcal sore throat in a tropical country

BACKGROUND

Acute rheumatic fever and rheumatic heart disease cause a high burden of disease in Fiji and surrounding Pacific Island countries, but little is known about the epidemiology of group A streptococcal (GAS) pharyngitis in the region. We designed a study to estimate the prevalence of carriage of beta-hemolytic streptococci (BHS) and the incidence of BHS culture-positive sore throat in school aged children in Fiji.

METHODS

We conducted twice-weekly prospective surveillance of school children aged 5 to 14 years in 4 schools in Fiji during a 9-month period in 2006, after an initial phase of pharyngeal swabbing to determine the prevalence of BHS carriage.

RESULTS

We enrolled 685 children. The prevalence of GAS carriage was 6.0%, while the prevalence of group C streptococcal (GCS) and group G streptococcal (GGS) carriage was 6.9% and 12%, respectively. There were 61 episodes of GAS culture-positive sore throat during the study period equating to an incidence of 14.7 cases per 100 child-years (95% CI, 11.2-18.8). The incidence of GCS/GGS culture-positive sore throat was 28.8 cases per 100 child-years (95% CI, 23.9-34.5). The clinical nature of GAS culture-positive sore throat was more severe than culture-negative sore throat, but overall was mild compared with that found in previous studies. Of the 101 GAS isolates that emm sequence typed there were 45 emm types with no dominant types. There were very few emm types commonly encountered in industrialized nations and only 9 of the 45 emm types found in this study are emm types included in the 26-valent GAS vaccine undergoing clinical trials.

CONCLUSIONS

GAS culture-positive sore throat was more common than expected. Group C and group G streptococci were frequently isolated in throat cultures, although their contribution to pharyngeal infection is not clear. The molecular epidemiology of pharyngeal GAS in our study differed greatly from that in industrialized nations and this has implications for GAS vaccine clinical research in Fiji and other tropical developing countries.

Variation in clinical presentation of childhood group A streptococcal pharyngitis in four countries

We conducted a cross-sectional study from September 2001 to August 2003 during which children between 2 and 12 years of age presenting with complaint of sore throat were recruited from urban pediatric clinics in Brazil, Croatia, Egypt and Latvia. The objective of the study was to compare clinical signs and symptoms of children presenting to urban pediatric clinics with sore throat in and between countries and to identify common clinical criteria predicting group A beta hemolytic streptococcal (GAS) pharyngitis. Using a single standard protocol in all four sites, clinical data were recorded and throat swabs obtained for standard GAS culture in 2040 children. Signs and symptoms were tested for statistical association with GAS positive/negative pharyngitis, and were compared using chi(2) tests, ANOVA and Odds Ratios. Clinical signs of GAS pharyngitis in children presenting to clinics varied significantly between countries, and there were few signs or symptom that could statistically be associated with GAS pharyngitis in all four countries, though several were useful in two or three countries. Our results indicate that the clinical manifestations of pharyngitis in clinics may vary by region. It is therefore critical that clinical decision rules for management of pharyngitis should have local validation.

Epidemiology and prevention of valvular heart diseases and infective endocarditis in Africa

Valvular heart diseases in Africa affect mainly children and young adults and are a result of rheumatic fever. Rheumatic fever is a preventable disease, but in Africa the combination of a lack of resources, lack of infrastructure, political, social and economic instability, poverty, overcrowding, malnutrition and lack of political will contributes to the persistence of a high burden of rheumatic fever, rheumatic valvular heart diseases and infective endocarditis. Combating and eradicating rheumatic fever and rheumatic heart diseases requires economic development and implementation of best practices of primary and secondary prevention measures. The barriers to achieving this goal in Africa are numerous, but not insurmountable.

Comparison of skin changes induced on mice by either group A type 12 or group G streptococci

Adult Swiss webster mice were injected with 3 x 10(6) colony-forming units (cfu) of group G or 2.5 x 10(6) cfu of group A streptococci at intradermal injection sites on the right and left paralumbar areas of the back. The mice were sacrificed at intervals between 4 hours and 14 days post-injection (p.i.) and full thickness biopsies of skin 10 mm in diameter encompassing the sites of injection were taken. One tissue specimen was homogenized in PBS and plated to determine the number of cfu, while another was used for histopathological studies. The number of viable group A and group G streptococci in the tissue increased to 3 x 10(9) cfu by 96 hours p.i.: after 192 hours p.i. the group A cells had declined to 2.7 x 10(6) cfu compared to 1.1 x 10(8) cfu for group G cells. No streptococci of either group were detected at 336 hours (14 days p.i.). Gross edematous lesions induced by either streptococcus group were evident on all animals at 24 hours (p.i.). Group G streptococci lesions were larger and persisted longer than lesions induced by group A. Histological examination consistently revealed more inflammation and necrosis in tissue sections from mice injected with group G streptococci.

A one-year study of streptococcal infections and their complications among Ethiopian children

Post-streptococcal complications are known to be common among Ethiopian children. Little is known, however, about the epidemiology of beta-haemolytic streptococci in Ethiopia. A total of 816 children were studied during a one-year period: 24 cases of acute rheumatic fever (ARF), 44 chronic rheumatic heart disease (CRHD), 44 acute post streptococcal glomerulonephritis (APSGN), 143 tonsillitis, 55 impetigo, and 506 were apparently healthy children. Both ARF and APSGN occurred throughout the year with two peaks during the rainy and cold seasons. The female:male ratio among ARF patients was 1.4:1 and 1:1.9 among APSGN. The monthly carrier rate of beta-haemolytic streptococci group A varied from 7.5-39%, average being 17%. T type 2 was the most frequent serotype. Marked seasonal fluctuations were noted in the distribution of serogroups among apparently healthy children. Beta-haemolytic streptococci group A dominated during the hot and humid months of February-May. Strains were susceptible to commonly used antibiotics, except for tetracycline.

An epidemiological survey of rheumatic fever and rheumatic heart disease in Sahafa Town, Sudan

STUDY OBJECTIVE

The aim was to determine the prevalence of rheumatic fever and rheumatic heart disease and to initiate a programme of secondary prophylaxis in Sahafa Town, Sudan.

DESIGN

The study was a prospective case finding survey, carried out by a specially trained team headed by a cardiologist.

SETTING

The study involved high risk school children (5-15 years of age) from Sahafa Town in the period 1986-1989.

SUBJECTS

A total of 13,332 children on the school registers (7892 boys and 5430 girls) were examined generally and specifically for evidence of rheumatic fever or rheumatic heart disease.

MAIN RESULTS

Out of the 13,322 children screened 351 were suspected cases and 146 were confirmed cases of rheumatic fever or rheumatic heart disease. The prevalence rates for all ages were 10/1000 for boys and 14/1000 for girls. The overall prevalence rate of the whole programme area was 11/1000, prevalence of rheumatic fever was 8/1000, and prevalence of rheumatic heart disease was 3/1000. The prevalence rate was significantly increased among the inner town inhabitants (15/1000) compared to the outer town inhabitants 4/1000 (p < 0.001). Monthly prophylactic benzathine penicillin in a dose of 1,200,000 IU was given to both suspected and confirmed cases. Penicillin coverage rate was 72%.

CONCLUSIONS

Rheumatic fever continues to be a serious health problem. With economic pressures causing impending change in socioeconomic conditions in most Third World countries in the immediate future, rheumatic fever will continue to have a high prevalence rate and rheumatic fever and rheumatic heart disease prevention programmes will remain a central goal.

Rheumatic heart disease in schoolchildren in western district, Saudi Arabia

The prevalence of rheumatic heart disease was assessed among schoolchildren aged between 6-15 years in the Western District. A sample size of 9,418 (10% of the target population) underwent cardiac evaluation. The prevalence of rheumatic heart disease was 24 per 10,000 schoolchildren (6-15 years). The prevalence was higher in rural areas and in females. This survey revealed that the carrier rate of beta-hemolytic streptococci was 34%.

Group C streptococci in human infection: a study of 308 isolates with clinical correlations

A collection of 308 clinical isolates of beta-haemolytic Lancefield group C streptococci was assembled from laboratories in England, Nigeria and New Zealand. Of these, 276 isolates were Streptococcus equisimilis, 23 S. milleri and nine S. zooepidemicus. Isolates of S. equisimilis in the African collection, though few, gave higher rates of lactose and raffinose fermentation, aesculin hydrolysis and positive alpha-galactosidase reactions than those from elsewhere. Erythromycin resistance was found in 1.9% of the English isolates of S. equisimilis. Strains from superficial infections accounted for 88% of the collection and were most commonly isolated from the upper respiratory tract, skin or wounds. Amongst the 36 patients yielding isolates from deep sites S. equisimilis was found in septicaemia, cellulitis, abscess, peritonitis, septic arthritis, pneumonia, mycotic aneurysm and acute epiglottitis, S. milleri was found in abdominal abscesses, peritonitis, pleural empyema and osteomyelitis and S. zooepidemicus was found in septicaemia, pneumonia, meningitis and septic arthritis. Within the collection an unselected general catchment of 214 isolates of group C streptococci from the laboratories in Yorkshire showed the following species: from 199 superficial infections 94% S. equisimilis, 5% S. milleri and 1% S. zooepidemicus and 15 patients with deeper, more aggressive infections 67, 27 and 6.7% of these species respectively.

Rheumatic heart disease in Nigerian children: clinical and preventive aspects

Ninety-two children with rheumatic heart disease were studied clinically, and through a post-diagnosis surveillance period of varying duration over a 10-year period. The logistics and effectiveness of secondary penicillin prophylaxis, administered monthly, were assessed during the surveillance period. Eighty-one (88%) of the 92 children were seen for the first time with already established rheumatic heart disease. Mitral insufficiency was the major functional defect in these children whose mean age was 8.6 years. There was a high default rate of just under 50% among children referred to the surveillance clinic. Socio-economic inadequacies were found to be major factors in the high default rate. Regular monthly parenteral penicillin was found to be effective in reducing recurrence of rheumatic fever and maintaining good health in these children.

Experimental necrotic dermatosis induced by group G streptococci in mice

Self healing necrotic lesions were produced on the backs of laboratory mice by injecting group G streptococci into the skin. The incidence and severity of necrotic dermatosis was dose related. When 1 x 10(1) colony forming units (cfu) were injected subcutaneously, lesions developed on three of 16 mice 4 days post inoculation. Injection of 1 x 10(3) cfu produced lesions on five of 16 mice and 1 x 10(5) cfu produced lesions on seven of 15 mice 3 days post inoculation. An inoculation of 1 x 10(7) cfu produced lesions on all of 16 mice 2 days post inoculation. Lesions produced by the 1 x 10(1) inoculum were smaller and had healed by the 15th day post inoculation, whereas lesions produced by the 1 x 10(7) inoculum persisted until the 24th day post inoculation. No mortality could be attributed to experimental design and all lesions healed without the use of medication or antibiotics.

Rheumatic fever in Nigerian children: a prospective study

The initial attack of acute rheumatic fever is hardly ever diagnosed in our environment. Most cases of acute rheumatic fever are seen during recurrent illness when cardiac damage is already severe and death from cardiac failure common. In the absence of effective primary prophylaxis against rheumatic fever in the foreseeable future it is important to find every case of acute rheumatic fever at the first attack, as on this would depend effective secondary prophylaxis and, hopefully, reduction of the morbidity and mortality rates. A prospective study was set up to achieve this aim. All cases suspected of having rheumatic fever among children seen at the Lagos University Teaching Hospital over a period of five years were subjected to the Jones' diagnostic criteria for diagnosis, and grouped into "Initial illness" and "Recurrent illness" groups. Twenty-one cases of acute rheumatic fever were diagnosed during the period, out of which ten (47.6%) were in the initial stage of the illness. There was a direct relationship between the severity of cardiac involvement and delay in recognition of the condition. It was concluded that efforts aimed at prompt recognition of the initial illness would be rewarding in minimising cardiac morbidity and mortality.