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Mumps outbreak at three International schools in the Eastern region 2009 (1430 H).

On Sunday 5/4/2009, the Preventive Medicine Department of the General Health Directorate of Eastern region reported an unusual increase in the number of Mumps cases, reported from three international schools in the region. The Eastern province is the largest Province of Saudi Arabia, located in the east of the country on the Arabian Gulf coast. It has an area of 710,000 km2 and a population of 3,360,157 (2004 census). Khobar and Jubail are two of the biggest cities in the province; the outbreak was at 3 international schools in the region (2 in Khobar and 1 in Jubail). The Field Epidemiology Training Program (FETP) was assigned to verify and investigate this outbreak and recommend control measures.
First, a descriptive cross-sectional study was conducted on the reported Mumps cases, followed by a case-control study. A case was defined as any person associated with one of the 3 international schools who had developed illness with acute onset of unilateral or bilateral tender, self-limited swelling of the parotid or other salivary gland(s) lasting at least 2 days, with fever, with or without serological confirmation during the period from 1/12/2008 to 4/5/2009. Controls were randomly selected class mates of cases, who had not developed any symptoms during the same time period.
The total number of cases reached 59 since the beginning of 2009. Of these, 53 (89.8%) were from one school (International Indian School in Khobar), 4 were from Almuatasim International School in Jubail and 2 from New World International School in Khobar. The nationality of most of the cases was Indian 52 (88.1%); 53 cases (89.8%) were males and 6 (10.2%) were females. Class distribution of cases showed that 36 (64.3%) were in grade 10, 14 (25%) were in grade four, and the rest were in different classes. Regarding age distribution of cases, 6 (10.2%) were eight years or less, 12 (20.3%) were between 9-12 years old, 38 (64.4%) were between 13-16 years, and three (5.1%) were 17 years and above.
Almost all cases had developed cheek swelling, 21 (35.6%) unilaterally and 37 (62.7%) bilaterally. Other symptoms were fever 48 (81.4%), cough 8 (13.6%), coryza 3 (5.1%), and headache 28 (47.5%); 53 cases (89.8%) had sought medicaltreatment at clinics or hospitals. One case had positive IgM but no symptoms. Complications occurred among 11 cases (18.6%).
Time distribution of Mumps cases showed that the outbreak began on 26/12/2008 when symptoms appeared on the index case. The next case appeared five days later with clear contact history with the index case. This was followed by an increase in the number of reported cases, showing a propagating type of outbreak. (Figure 1).
Thirty eight cases (64.4%) had been vaccinated, 15 (25.4%) had not been vaccinated and 6 (10.2%) did not know.
A total of 153 persons were included in the case control study, 59 (38.6%) cases and 94 (61.4%) controls. The International Indian School in Khobar had the highest number of cases 53 (89.8%). Schools were not significantly associated with infection (P-value=0.70), neither was age (P value=0.80), nationality (OR 1.3, 95% CI= 0.45-3.84, P-value= 0.60), gender (OR=1.05, 95% CI= 0.36-3.06 for males, P value= 0.93), history of contact with a mumps case (OR= 1.57, 95% CI =0.68-3.67, P-value= 0.25), nor history of travel in the 2 weeks before symptoms appeared (OR= 3.79, 95% CI= 0.64-28.75, P-value= 0.09).
The only significant risk factor of infection was vaccination status, which was higher among controls (64.4% of cases compared to 86.2% of controls). After exclusion of those who did not know their vaccination status, an OR of 0.13 was calculated, showing a protective association against infection (95% CI= 0.03-0.44, P value <0.01).
Among all cases and controls, 44 individuals (28.8%) had the serological test for Mumps; among 32 cases who had the test, 26 (81.3%) had positive IgM results. All controls (100%) had a negative IgM result. Over half of the positive IgM cases, 14 (53.8%), were in the 13-16 years old age group.
The first case in this outbreak (index case) was a Srilankan teacher working at Almuatasim International School in Jubail, who had arrived from vacation in her country two weeks earlier. Propagation of infection between schools came later on by direct contact between some of the students of Almuatasim International School and the International Indian School in an evening course that was held in Khobar on January 1, 2009.

Editorial note:

Mumps or epidemic parotitis is an acute communicable viral disease of humans, characterized by fever and painful swelling of one or both parotid glands. It spreads from person-to-person by contact with respiratory secretions such as saliva from an infected person. It can also spread by sharing food, drinks, and kissing. Mumps is caused by infection with the mumps virus, a single-stranded RNA virus and a member of the family Paramyxoviridae, genus Paramyxovirus. After entry into the oropharynx, viral replication occurs, causing subsequent viremia and involving glands or nervous tissue. The virus may be isolated from saliva, blood, urine, and cerebrospinal fluid.1,2

The disease is generally self-limited, within seven days, with no specific treatment. The incubation period is 16-19 days, and mumps is communicable from six days before to nine days after facial swelling is apparent. However, 30% of infections are subclinical. Symptoms mostly consist of fever, headache, and malaise. Within 24 hours, one or both parotid glands begin to enlarge; 70-80% of cases are bilateral. The swelling is usually associated with pressure pain and may require as long as 10 days to subside.4,5 As a complication of mumps, approximately one third of post-pubertal male patients develop unilateral orchitis. Bilateral orchitis occurs much less frequently, and although gonadal atrophy may follow orchitis, sterility is rare. Other Complications may occur like acute encephalitis, oophoritis, and myocarditis.1,2
Mumps remains endemic in many countries throughout the world, and the vaccine is used in only 57% of countries that belong to WHO, predominantly in developed countries. In the United States, with the introduction of 2 doses of MMR vaccine in the 1990s, mumps cases substantially declined from 5,292 in 1990 to 266 in 2001 and 231 in 2003.3
Mumps outbreaks usually occur among susceptible individuals; this could be attributed to primary vaccine failure, e.g. impotent vaccine, improper vaccine storage and improper administration techniques, waning immunity e.g. lack of continuous antigenic stimulation, or accumulation of unimmunized persons or children too young to be immunized. However, more than 95% of children who receive MMR vaccine develop long lasting immunity that may be lifelong.4
In 1991, Saudi Arabia started requiring mandatory MMR vaccinations for preschool populations. Since the introduction of MMR vaccination, a sub-
substantial decrease in mumps cases has been reported. From 1991 to 1997, national coverage of MMR vaccination has ranged between 76% and 91%. In 1998 an outbreak of mumps occurred in a highly vaccinated population among primary and intermediate school students in Riyadh city, when 64 confirmed mumps cases were reported, the first case in a 12-year-old child. The median age of mumps cases was 12 years (range: 9 months to 33 years) and 91% of them had been vaccinated. Of the 64 cases, children 10-14 years of age had the highest incidence rate of mumps with an attack rate of 31/1000 population. In the last few years, coverage of MMR vaccination has further improved, reaching up to 98%.12,13 Since 2002, the EPI vaccination schedule has included a first dose of MMR vaccine to be given at age one, followed by a second dose at school entry.
In this study, up to April 9, 2009, a total of 59 confirmed cases of Mumps had been reported. Based on review of the data since 1993, this number clearly exceeds the normal occurrence of Mumps in the region and should be considered of epidemic nature.5
The first case in this outbreak (index case) appeared on 26/12/2008. However, delayed notification by the schools led to an increase in the number of cases. This also led to delay in implementation of preventive measures by the preventive department in the region.
The role of vaccination failure is often difficult to assess. However, the accepted failure rate (derived from serological result) is in the range of 2% to 10%. A study reported that the finding of IgG seronegativity of randomized vaccinated population under 10 years of age was 10.5%, which warns of future outbreaks.6
The only variable significantly associated with infection in this study was vaccination status. However, it should be mentioned that the vast majority of cases occurred among a population that is not covered by the current vaccination strategy in the Kingdom. Other factors that may have played a role may have been primary vaccine failure and/or waning immunity.
Although the local health authorities have taken a number of appropriate measures to control the outbreak, it was recommended to isolate Mumps cases, where feasible, for its period of communicability. It was also recommended to vaccinate contacts of cases of all ages, whether at the three international schools or living in the same household, with the MMR vaccine, preferably within 72 hours of occurrence of the case. Routine MMR vaccination at school entry should be strengthened. Vaccination status of non-Saudi residents should be checked, and their vaccination records maintained.
1.Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL, Isselbacher KJ, Eds. Harrison's Principles of Internal Medicine (16th Ed.). McGraw-Hill Professional 2004.
2.CDC.Brief report: update: mumps activity--United States, January 1 — October 7, 2006.MMWR Rep.Oct 272006; 55(42):1152-3.
3.Hviid A, Rubin S, Mühlemann K. Mumps. Lancet. 2008; 371 (9616): 932–44.
4.Abram S. Benenson, Ed. Control of Communicable Diseases Manual: Mumps; American Public Health Association. 1995; 315-317.
5- Ministry of Health, Saudi Arabia.Annual health report 2002. Riyadh: MOH, Saudi Arabia.
6-Pebody RG. Immunogenicity of second dose measles-mumps-rubella (MMR) vaccine and implications for serosurveillance. Vaccine 2002; 20 (78): 1134-114.
تقرير أولي حول فاشية مرض النكاف في المنطقة الشرقية 1430هـ (2009 م)

النكاف مرض معد يصيب الإنسان و يسبب إلتهاب حاد في الغدد اللعابية و الجهاز العصبي و أجزاء أخرى من الجسم. مدة الحضانة تتراوح مابين 16 إلى 19 يوماً. يبدأ المرض بارتفاع في درجة الحرارة و صداع ثم يظهر ورم في إحدى الغدتين اللعابيتين ثم تهبط درجة الحرارة و تعود الغدد لحالتها الطبيعية بعد حوالي 7 أيام .

في يوم الأحد 5/4/2009م أبلغت إدارة الطب الوقائي في المنطقة الشرقية برنامج الوبائيات الحقلي عن 59 حالة نكاف خلال هذا العام 2009م في 3 مدارس عالمية في المنطقة. وعلى الرغم من الإجراءات المتخذة من الطب الوقائي إلا أن الحالات استمرت في الظهور. بناءًا على هذا فقد قرر برنامج الوبائيات الحقلي القيام بدراسة حول فاشية النكاف في الجبيل والخبر لمعرفة مصدر العدوى والتوصل إلى توصيات من شأنها السيطره على هذه الحالة ومنع حدوثها في المستقبل. قرر فريق العمل اجراء دراسة ضابطة لإنجاز أهداف هذه الدراسة.

عدد الحالات المصابة في الثلاث مدارس كانت 59 حالة، معظمها (89.8%) في المدرسة الهندية العالمية في الخبر، و كانت 52 حالة (88.1%) من الجنسية الهندية. بلغ عدد الذكور 53 (89.8%) وعدد الإناث 6 (10.2%). تراوحت أعمار المصابين بين 15 إلى 43 سنة (متوسط 13.8 و إنحراف معياري ± 5.3). كانت أكثرالحالات في الفئة العمرية من 13 – 16 سنة (64.4%).

بدأت الفاشية في الجبيل وبالتحديد في مدرسة المعتصم العالمية، حيث ظهرت أولى الحالات، و التي كانت مدرّسة من الجنسية السرلانكية تبلغ من العمر 37 سنة كانت قد وصلت خلال أسبوعين من بلدها، ومن المحتمل أن تكون مصدر العدوى، حيث بدأت الحالات بالظهور بعد وصولها و خلال فترة حضانة المرض. وقد أدى إتخاذ مكتب الطب الوقائي في الجبيل الإجراءات الوقائية اللازمة وتطعيم كل طلاب ومنسوبي المدرسة إلى توقف تفشي المرض في المدرسة. لكن وفي نفس الفترة بدأت حالات نكاف جديدة تظهر في المدرسة الهندية العالمية في الخبر. وكان تأخر إدارة هذه المدرسة في التبليغ عن الحالات المصابة سبباً في تفشى المرض بصورة كبيرة بين طلاب المدرسة وبعض منسوبيها، كما تسبب ذلك في إنتقال المرض الى طلاب مدرسة عالمية أخرى في الخبر، حيث اجتمع طلاب من المدرستين في دورة مسائيه في نفس الفترة.

كانت التطعيمات عند غالبية الحالات غير واضحه وغير مسجله في ملفات الطلاب في المدارس الثلاث، كما أن نظام التسجيل في المدارس لا يشترط إرفاق بطاقة التطعيمات الخاصة بالطالب مما قد يوحي إلى أن من أسباب ظهور الفاشية هو عدم تطعيم الطلاب.

قد يكون سبب زيادة الإنتشار هو تلاشي مفعول أي جرعة MMR سابقه أما في الفئة الثانية فذلك غالباً بسبب عدم أخذ تطعيمة MMR قبل دخول المدرسة. بدأ عدد الحالات في المدرستين بالإنحسار بعد إتخاذ مكتب الطب الوقائي في الخبر الإجراءات الوقائية اللازمة و تطعيم الطلاب.

تمت التوصية على التقيد بجدول التطعيمات الأساسية المقرر من وزارة الصحة السعودية والتأكيد على جميع المدارس سواء الحكومية أو الخاصة بإتباع الشروط والقوانين في قبول وتسجيل الطلاب ومنها الإلزام بإرفاق بطاقة التطعيمات كاملة مع أوراق التسجيل، إضافة إلى الإهتمام بنظام المراقبة الوبائية وتوعية العاملين في القطاعات الصحية الحكومية والخاصة وكذلك المدارس العالمية بأهمية التبليغ عن الحالات بصورة صحيحة وسريعة.