Epidemiology and prevention of streptococcal pharyngitis Prepared by: Ghada Mohamed Ahmed Bedair Ghada_epi@yahoo.com B.Sc, Nursing, Faculty of Nursing, Alexandria University. Master degree in Epidemiology, High Institute of Public Health, Alexandria University, Egypt
Definition: - Pharyngitis refers to inflammation of the structures of the pharynx. - The tonsils are most often affected. - The term pharyngitis, tonsillitis, tonsillopharyngitis and pharyngotonsillitis are interchangeable and do not imply an etiology.
Causes: - Up to 85% are caused by viruses. - Pharyngitis caused by Streptococcus pyogenes is the most common bacterial pharyngitis diagnosed in developed countries. SStreptococcus pyogenes, Group A- Beta haemolytic streptococci (GAβHS) is a gram positive, catalase negative, facultative anaerobe, that occurs in pairs or chains in cultures. GA βHS divided into more than 130 distinct M serotypes.
GA βHS represent one of the most impressive human pathogens, it cause a wide array of serious infections including: Pharyngitis Respiratory infection Skin infection (impetigo, erysipelas) Endocarditis Meningitis Puerperal sepsis Arthritis Scarlet fever
It is a precursor of two serious non- suppurative sequlae; acute rheumatic fever, and post streptococcal glomerulonephritis. PPublic health importance :
Risk factors: 1. All group A streptococcal diseases are most common in setting of poverty, overcrowding, and low socioeconomic status, where living conditions promote transmission of the organism. 2. Streptococcal pharyngitis most often occurs in the late winter and early spring. 3. It affects school–age children, particularly those 5- 11 years old, but children and adults of all ages can be infected with group A streptococci.
of GAβHS: Mode of transmission GA βHS spread when a person coughs or sneezes infected large droplets that come into contact with another person’s mucous membrane. The highest risk of transmission occurs during the acute stage.
GAβHS diseases are highly prevalent in some regions, but may be less in others, For example, RHD is very common in Sub-Saharan Africa and the Pacific, common in South-Central Asia and the Middle East/North Africa, but less common in many Asian countries and Latin America. From 1985 through 2002, the world Health Organization (WHO) estimated that over 600 million cases of symptomatic GAS pharyngitis occur annually worldwide. Magnitude of the Problem
GA β HS pharyngitis in some developed countries: Acute pharyngitis is one of the most common illnesses for which patients seek medical advice in the more developed countries. accounting for nearly over 7 million visits to pediatricians each year in the United States. In this country. Oliver (2000) in England reported that the prevalence of GAβHS was 20%. In France, Chiadmi et al (2003) stated that the prevalence was 33%. In Belgium, sore-throat is one of the most frequent causes of consultation seen by general practitioner, and GAS has been isolated in 20.3% of cases. In Chile, a study done by Munoz et al (2003-2004), streptococcus sore-throats were detected in 37% of cases.
GAβHS pharyngitis in some developing countries In low income countries, there are few prospective studies that provide data on group A streptococcal pharyngitis, its epidemiology and clinical presentation.
In India, it is estimated that approximately 7 sore throat episodes occur per child per year, there are as many as 20-30 million cases of streptococcal pharyngitis may occur annually in that country in Asia. In Iran (2000) Jasir et al reported a prevalence of 30%. Shrestha et al in Nepal (2001) reported prevalence 7.2%. Dos Santos and Berezin in Brazil (2004) found the prevalence of GAβHS pharyngitis (24.4%). In Taiwan Lin et al (2003) reported s prevalence of 21.4% A study done in 3 countries from September 2001 to August 2003, Rio de Janeiro (Brazil), Cairo (Egypt), Zagreb (Croatia), the proportion of children with a positive GAβHS culture differed between countries: 24.6% in Brazil, 42.0% in Croatia, and 27.7% in Egypt.
Prevention and control of GAβHS pharyngitis Primary prevention: A) Reducing overall exposure to GAS. 1) Improving living standards. 2) Adequate nutrition. 3) Provision of easily accessible laboratory facilities for diagnosis of GAβHS. 4) Pasteurization of milk and exclude of infected people from handling food. 5) Health education to public and health workers about modes of transmission and the relationship of streptococcal sore throat to ARF/RHD.
B) Immunization: Although there have been multiple attempts to produce a GAβHS vaccine for approximately a century, none of the candidate vaccines has proceeded beyond preliminary animal or human studies until recently.
Secondary prevention A- Treatment of GAβHS pharyngitis: The gold standard of therapy for GAβHS is penicillin. Treatment of GAβHS pharyngitis should, 1) Relieve the symptoms of the acute illness. 2) Eliminate transmissibility. 3) Prevent both suppurative and nonsupporative sequelae.
It has been very well demonstrated that a 10 days course of an appropriate oral antibiotic (usually oral penicillin V) or a single dose of long-acting intramuscular penicillin (benzathine penicillin –BPG) if administered within 9 days of the onset of symptoms of GAβHS pharyngitis, will prevent most cases of ARF.
B) Primary prophylaxis of RF: This refers to the prevention of ARF by timely and complete antibiotic treatment of symptomatic GAβHS pharyngitis. C Surgical approach to recurrent GAβHS pharyngitis: More clearly defined indicators for surgical intervention include patients with peritonsillar abscess or severe obstructive symptoms.
Tertiary prevention This refers to measures to reduce the severity or long-term impact of GAS diseases. In practice, it mainly refers to management of patients with RF/ RHD.
General objective: To study group A-β haemolytic streptococci (GAβHS) among school children with Pharyngotonsillitis in Alexandria (Egypt).
Specific objectives: 1-To estimate the prevalence of GAβHS infection among school children with pharyngotonsillitis. 2-To identify the predictive clinical findings of GAβHS pharyngitis. 3-To determine the seasonal variations of GAβHS pharyngitis.
Study design: Cross-sectional approach Study setting: School health insurance clinics in six educational zones in Alexandria (Egypt). Target population: School children aged 6-15 years old with pharyngotonsillitis in primary and preparatory education in Alexandria.
Sampling design: Based on data from the Medical Affairs for School Children, the sample size was calculated by using epi-info program, on the assumption that the prevalence is 17% according to the last study by zaher et al, the calculated sample size at 95% confidence interval and at degree of precision of 3% was found to be 600 students.
To fulfill this sample size; multistage sample technique was used. One school health insurance clinic was randomly chosen from each educational zone. Then the total sample size was proportionally distributed on chosen health clinics.
Ethical considerations: 1- Getting approvals from the Medical Affairs for School Children. 2- Informed consent was taken from enrolled child and parents or guardian accompanying the child to the clinic.
Study tools: 1- A predesigned questionnaire interview with child and his/her parent, inquiring about : Demographic characteristics( child name, age, sex,.......) Co-morbidity and past history of diseases for both child and his family. Clinical signs and symptoms predicting GAβHS pharyngitis which extracted from the literature. 2- Throat swab was taken from each child to be cultured on blood agar plate.
Inclusion criteria: Sore- throat and/or difficult swallowing. Pharyngeal erythema, exudates. Or tonsilar enlargement, redness with or without exudates. Fever. Enlarged tender anterior cervical lymph nodes. Exclusion criteria Oral antibiotic use within 3 days or intramuscularly administered antibiotics within the 20 days prior to the clinic visit. History of previous RF or RHD, or presence of another illness requiring hospitalization.
Implementation phase Selection and examining of cases were done by clinic physician. Questionnaire interview, Throat swab sampling and cultures were made by the researcher. The cultures were made in Microbiology Department of High Institute of Public Health.
Transport samples to the laboratory The swabs were transported to the laboratory within 2 hrs. If there is delay in transportation to the laboratory, they were put in transport medium (stuart’s media) Procedure of cultivation and identification Swabs were streaked onto crystal violet blood agar plate and incubated at 37°C in 5-10% CO2 atmosphere using candle jar. After overnight incubation, the plate were examined for bacterial growth, colonial morphology and haemolytic characteristics.
Colonies that appeared on blood agar plate as pinpoint, transparent, circular colonies surrounded by wide zone of β haemolysis were suspected as GAβHS, and subcultured on another crystal violet blood agar plate and tested for their sensitivity to bacitracin discs (0.05units).
Interpretation of results : Beta haemolytic streptococci strains showing zone of inhibition around bacitracin disc, were considered to be GAβHS.
Data analysis and interpretations: FFrequency distribution and chi-square test were calculated for each signs and symptoms. LLogistic regression analysis was used to model the probability of GA βHS pharyngitis occurrence.
From the present study, it could be concluded that: The prevalence of GAβHS infection among selected primary and preparatory school children suffering from pharyngotonsillitis in Alexandria during 2005-2006 was 30.3%. The peak prevalence of GAβHS pharyngitis occurred in spring and winter. Cases who reported family history of rheumatic disease had the highest percent of positive culture of GAβHS pharyngitis (37.2%). Cases who reported a history of recent contact with pharyngotonsillitis had a higher prevalence of GAβHS pharyngitis (58.8%), compared to cases without such history, the prevalence of GAβHS among whom was 41.2%. The predictors which were found to be highly associated with GAβHS pharyngitis were: recent contact with a pharyngotonsillitis case, tender cervical lymph nodes, enlarged cervical lymph nodes, enlarged tonsils, joint/limb pain, and vomiting.
1. To encourage national authorities to include this disease and its complications in their public health priorities. 2. To develop an educational materials and training programs for health care providers and laboratory personnel which include standard guidelines addressing: recognition of GAβHS pharyngitis, clinical diagnosis, case management, and prevention of group A streptococcal sequelae.
3- To Upgrade the skills of school health physicians and To train them on early detection of GAβHS pharyngitis cases depending on the predicting signs and symptoms. 4- To carry out Further research to continually re- evaluate continually the clinical signs and symptoms associated with GAβHS pharyngitis in light of epidemiologic and demographic characteristics of such infection in our community to reach an accurate clinical diagnosis.