epidemiology and prevention of streptococcal pharyngitis

الله بسمالرحيم الرحمن

Epidemiology and prevention of streptococcal pharyngitis

Prepared by: Ghada Mohamed Ahmed Bedair

Ghada_epi@yahoo.comB.Sc, Nursing, Faculty of Nursing,

Alexandria University.Master degree in Epidemiology, High Institute of Public Health, Alexandria

University, Egypt

Introduction

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.

GAβHS divided into more than 130 distinct M serotypes.

GAβHS 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

GAβHS 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

GAβHS 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.

Clinical Pictures

Diagnosis of streptococcal pharyngitis

Complications of GAβHS pharyngitis

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 preventionA- 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.

CSurgical 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.

AIM OF THE STUDY

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.

SUBJECTS AND METHODS

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 GAβHS pharyngitis occurrence.

Results

Overall prevalence of GAβHS pharyngitis among primary and preparatory school children in Alexandria during

2005-2006.

Prevalence of GAβHS pharyngitis cases according to educational zones among primary and preparatory school children in Alexandria

(Egypt) during 2005-2006.

Prevalence of GAHS pharyngitis cases according to sex in Alexandria during 2005-2006

PPrevalence of GAβHS pharyngitis cases according to educational stage among primary and preparatory school

children in Alexandria during 2005-2006. *

Prevalence of GAβHS pharyngitis cases according to age group among primary and preparatory school children in Alexandria

during 2005-2006. *

PPrevalence of GAβHS pharyngitis cases according to Season among primary and preparatory school children in Alexandria

* during 2005-2006.

0

10

20

30

40

Winter Spring Summer Autumn

28.6% 29.1%

23.6%

18.7%

Distribution of cases according to history of family diseases among primary and preparatory school children in Alexandria

during 2005-2006.*

Distribution of cases according to history of recent contact with

pharyngotonsillitis among primary and preparatory school children in

Alexandria during 2005-2006.*

Distribution of cases according to number of sore-throat attacks per year among primary and preparatory school children in Alexandria during 2005-2006.*

predictors for GAβHS pharyngitis among primary and preparatory school children in Alexandria during 2005-2006

Model β coefficient

Odds ratio

Confidence interval LowerUpper

Tender cervical lymph nodes

1.3033.6812.0806.516

Recent contact with pharyngotonsillitis

1.4414.2262.7626.467

Enlarged cervical lymph nodes

0.8412.3201.2434.329

Joint/Limb pain0.5291.6971.1072.603Vomiting0.4611.5861.0452.405Enlarged tonsils0.7582.1531.0424.375

CONCLUSIONS

CONCLUSIONSFrom 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.

RECOMMENDATIONS

RECOMMENDATIONS1. 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.

Thank you