Article Info
Year: 2008
Month: April
Issue: 2
Pages: 11-12
Reference: Sharaheeli J., Choudhry A., Nooh R., .Saudi Epidemiology Bulletin. 2008;15(2):11-12.
From the 1st of January to the end of July 2007 G (1428H), there was an increase in the number of measles cases in Assir region, with 552 suspected and 247 confirmed cases. The highest number (132) was reported from Tathleeth sector, in Eastern Assir. This was the first reported measles outbreak in Tathleeth. The objectives of this study were to describe the distribution and dynamics of this outbreak, assess measles vaccination status of children registered at Primary Health Care Centers (PHCC), and recommend appropriate measures for improvement of vaccination to prevent future measles outbreaks.
A cross-sectional study was conducted to describe the current outbreak, in addition to a retrospective cohort study for children registered at PHCC for the Expanded Program of Immunization (EPI) to evaluate the role of timing of vaccination in the occurrence of measles. The study population for the cross-sectional study, was all measles cases reported from January to July 2007 from all PHCCs in Tathleeth sector. For the retrospective cohort study, the population was all children registered at PHCCs for EPI during the period 2000-2005, from 4 PHCCs launched before 2000, Tathleeth, Amwah, Jash, and Subaikhah. A case was defined as any person who had fever and skin rash and/or laboratory confirmed in Tathleeth sector from January to July 2007.
A total of 132 cases were registered at 12 PHCCs of Tathleeth during the study period, of which the highest 58 (44.0%) were registered at Tathleeth PHCC, where the first case appeared. The onset of the outbreak was January 2007, the offset was in July 2007, and the peak was in April 2007, as shown in figure 1.
Among the total cases, there were 67 (50.8%) females and 65 (49.2%) males. Ages ranged between 5 months-50 years (mean 15 and 5 months, ± SD 12). All cases were Saudis except one.
Among all cases, 15.0% resided inside Tathleeth city, and 44.0% had been treated at Tathleeth PHCC. All cases (100.0%) experienced fever and skin rash, 24.0% loss of appetite, 22.0% headache, 6.0% cough, 4.0% fatigue, 2.4% vomiting, and 0.7% had either abdominal pain, diarrhea, pallor, dizziness or red eyes. There was no history of contact with a known measles case.
Among females, 78.0% were non-vaccinated, 12.0% partially vaccinated and 10.0% completely vaccinated. Among males, 37.0% were non-vaccinated, 15.0% partially vaccinated and 48.0% completely vaccinated. Partial vaccination was defined as receiving only a single dose of either MMR1 (1st dose MMR vaccine) or measles vaccine. Complete vaccination was defined as receiving 2 doses either (MMR1+measles vaccine) or (MMR1+MMR2) or 3 doses (MMR1+MMR2+measles). Laboratory results showed that 97 cases were anti-measles IgM positive.
In the retrospective cohort study, from 2000 to 2005, 5447 children were registered at the participant PHCCs. By the time of data collection (July 2007), 27 (0.5%) had died and 756 (13.9%) had moved. There were 3154 (57.9%) children from Tathleeth PHCC, 1084 (19.9%) from Amwah, 622 (11.4%) from Jash and 587 (10.8%) from Subaikhah. Among them, there were 49.2% females and 50.8% males. Their ages ranged between 19-92 months (mean 54 months, SD ± 20 months). Cases were almost evenly distributed among age groups. Most of the children resided outside Tathleeth city (80.0%).
Among the studied children, 87.2% had received at least one dose of vaccination, while 12.8% had not been vaccinated at all. Overall, 33.1% had been completely vaccinated, and 54.1% partially vaccinated. Of the total, 84.7% had received MMR1 vaccine by the time of record review. The highest percentage vaccinated was among those who had been registered during 2000 (98.2%), and the lowest among those registered during 2001 (80.3%). The highest percentage of vaccination was among those registered at Subaikhah PHCC (99.8%); and the lowest at Amwah (71.4%). Almost complete MMR1 vaccination pattern was observed at Subaikhah PHHC throughout the study period. Jash PHCC showed consistent over 90.0% MMR1 vaccination with minor fluctuation, while Amwah PHCC showed a very high peak of 98.6% in 2000 which fell to 21.0% in 2001, and fluctuating widely since then. Tathleeth PHCC showed a gradual uneven decline from 97.7% in 2000 to 75.4% in 2005.
Only 6.0% of children had received the 2nd dose of MMR vaccine (MMR2), the highest was among those registered during 2002 (21.8%), followed by 2003 (11.1%), 2001 (1.4%) and 2000 (0.3%). Children registered during years 2004 and 2005 had not received the MMR2.
Among the total study subjects, 29.9% had received the Measles vaccine as part of EPI: 95.1% of children registered in 2000 and 78.7% of those registered in 2001.
When vaccination status was stratified by current age, 80.7% of children “19-30 months” and 84.4% of the “31-42 months” age groups had received MMR1 dose alone. Among children 43-54 months of age, 73.6% had received
MMR1 alone and 11.0% had received MMR2; among children 55-66 months, 60.7% had received MMR1 and 21.9% had received MMR2. Only 77.4% of children in the 67-78 months age group had received MMR1 alone and 1.5% had received MMR2; 97.9% of children 79 months and above had received MMR1 alone and only 0.2% had received MMR2.
The Saudi EPI program recommends that all children receive MMR1 at 12 months of age and MMR2 at school entry (4-6 years). In line with these recommendations, delay in MMR1 vaccination was defined as any child who had not received his/her MMR1 or had received it at or after 13th months. Among the studied children, 50.7% had delayed MMR1 vaccination. The proportion of those who had delayed vaccination did not show any specific trend and fluctuated between 41.9% and 60.0% over the years. Within the PHCCs, Subaikhah performed better than others (28.5% delayed vaccination) and poorest in Amwah (67.2% delayed vaccination). When delay in vaccination was assessed by current age, among children 19-42 months, 82.7% had received MMR1 on schedule before 13 months. Among children 67-92 months, only 0.9% had received MMR2 on schedule, while 99.1% had not. Although 16.3% of children aged 43-66 months had received MMR2 vaccine, however, keeping in view the recommended age of vaccination (4-6 years), it is not possible to comment on the proportion not on schedule at this stage.
Editorial note:
Measles is a highly infectious viral disease caused by a Morbillivirus. Humans are the only reservoir. Transmission is primarily person-to-person via aerosolized droplets or direct contact with nasal and throat secretions of infected persons. In a non-immune person exposed to measles, after an incubation period of about 10 to 12 days (range 7-18 days), prodromal symptoms of fever, malaise, cough, coryza (runny nose), and conjunctivitis appear. Within 2 - 4 days of prodromal symptoms, a maculo-papular rash appears behind the ears and on the face along with high fever. The rash spreads to the trunk and extremities and lasts 3-7 days. Individuals with measles are infectious 2 - 4 days before through 4 days after rash onset. Measles leads to complications, and even deaths, among those under 5 and over 20 years. There is probably lifelong immunity, both after natural infection or vaccination. The efficacy of measles vaccine is 85.0% globally and 90.0% if administered at 9 months and higher if given later.1
The EPI is one of the most cost-effective health programs.2 In Saudi Arabia, vaccination against measles began in 1974 for children aged 1 to 9 years. One-dose Schwartz vaccine became a compulsory requirement for obtaining a birth certificate in 1982, to increase the coverage rate, which subsequently rose from 8.0% in 1980 to 80.0% in 1984 and to over 90.0% in 1990. Although this was accompanied by a remarkable decrease in measles incidence, the overall impact of measles immunization was unsatisfactory. The two-dose schedule was implemented in 1991, with the first dose given at 6 months of age, followed by a second dose at 15 months. In 2002, the schedule was changed to a first dose of MMR given at 12 months followed by a second dose at 5 years. However, since this change, a number of outbreaks of measles have been reported in different parts of the Kingdom.3 Some of the suspected reasons for these outbreaks are decreased threshold of herd immunity besides the increased proportion of susceptible individuals, which may be compounded by vaccine failure of the first dose. Explosive outbreaks with devastating clinical and public health consequences can occur in an environment that has been free of measles for more than a decade. Transmission of the measles virus, once reestablished, can be very difficult to interrupt.4,5
Measles epidemics can occur even in highly vaccinated populations. This can be contributed to a variety of factors including failure to seroconvert and waning of vaccine-induced immunity. The mean duration of vaccine-induced protection in the absence of re-exposure is 25 years. However, after long-term absence of circulatory virus, the mathematical model predicts that all seroconverted vaccinees have titers below the protective threshold.4,5,6
The most likely incriminated factors in the development and spread of the current measles outbreak in Tathleeth region were reduced herd immunity, low vaccination coverage and delayed administration, increased susceptible individuals, congested populations, nature of measles epidemiology and nature of vaccines against it.
Vaccination against measles needs to be strengthened in Tathleeth, particularly in the catchment areas of Amwah and Tathleeth PHCCs. This is required both in terms of quantity and quality, i.e. improving the proportion of children to be vaccinated in a timely manner. The supervisory mechanism for EPI also requires strengthening, with continuous evaluation and active response. A vaccination campaign was suggested to provide an additional 2nd dose of MMR/Measles to children registered in years 2000 and 2001. Children who have not received the 2nd dose of MMR/Measles should be targeted for vaccination.
References:
1. Regional Office for Africa. Guidelines for Measles Surveillance. Geneva: WHO; 2004; 3.
2. WHO. Eliminating measles and rubella and preventing rubella infection: WHO European Region strategic plan 2005-2010. Denmark: WHO Regional Office for Europe. 2006; 1.
3. Khalil MKM, Al-Mazrou YY, AlHowasi MN, Al-Jeffri M. Measles in Saudi Arabia: from control to elimination. Ann Saudi Med 2005; 25(4):324-328.
4. Jansen VAA, et al. Measles outbreaks in a population with declining vaccine uptake. Science. 2003; 301(5634):804.
5. Parker AA, et al. Implications of a 2005 Measles Outbreak in Indiana for Sustained Elimination of Measles in the United States. NEJM. 2006; 355:447-455.
6.Yeung LF, et al. A limited measles outbreak in a highly vaccinated US boarding school. Pediatrics 2005; 116:1287-1291.
توقيت التحصين ضد الحصبة و دوره في تفشي الحصبه في منطقة تثليث عام 1428هـ (2007م).
الحصبة مرض فيروسي شديد العدوى ينتقل من شخص لآخر عبر الإفرازات الأنفية أو عبر الرذاذ المنتشر في الهواء. أهم الأعراض المصاحبة له حرارة شديدة وطفح جلدي و وهن عام. قد تحدث مناعة ضده مدى الحياة بعد الإصابة به أو بعد التطعيم ضده. يعتبر اللقاح الواقي من الحصبة فعال بشكل كبير وهو متوفر من حوالي 40 سنة و كان يعطى بمفرده بمقدار جرعة واحده ثم أصبح يعطى ضمن لقاح الثلاثي الفيروسي MMR بمقدار جرعتين. بدأ تقديم لقاح الحصبة في المملكة العربية السعودية عام 1974م بمقدار جرعة واحدة من عمر1-9 سنوات وفي 1982م صدر مرسوم ملكي بأن يكون لقاح الحصبة ضمن متطلبات الحصول على شهادة الميلاد للطفل. لم تسجل أي فاشية للحصبة في منطقة تثليث وهذه تعتبر أول فاشية للحصبة في هذه المنطقة.
هدفت الدراسة إلى وصف كامل لفاشية الحصبة الحالية في منطقة تثليث، تقييم دور توقيت التطعيم ضد الحصبة في ظهور هذه الفاشية، و تقديم التوصيات اللازمة للوقاية من مثل هذه الفاشية.
تكونت الدراسة من جزئين. الجزء الأول دراسة مقطعية عرضية للفاشية الحالية، والجزء الثاني دراسة قطيعية استرجاعية لجميع الأطفال الذين تم تسجيلهم في سجلات الفحوصات بالمراكز الصحية خلال الأعوام من 2000-2005م.
بالنسبة للجزء الأول من الدراسة، تم أخذ كل الحالات (132) التي سجلت في جميع المراكز الصحية (12 مركز). و بالنسبة للجزء الثاني تم أخذ كل الأطفال المسجلين في السجلات من 2000-2005م من 4 مراكز صحية من أصل 8 ، أنشئت قبل عام 2000م، وهذه الأربعة هي مركز صحي تثليث، مركز صحي الأمواه، مركز صحي الصبيخة، و مركز صحي جاش.
عرفت الحالة كأي شخص ظهرت عليه الحمى والطفح الجلدي بالإضافة الى النتائج المخبرية من يناير 2007 الى يوليو 2007 في منطقة تثليث.
فيما يتعلق بالدراسة المقطعية للفاشية التي بدأت في يناير وانتهت في يوليو 2007، كان هناك 132 حالة سجلت في تثليث وظهرت ذروة الحالات في شهر يوليو 51,5% وكانت أغلب الحالات (44%) بالإضافة إلى أول حالة مسجلة في مركز صحي تثليث. نسبة الإناث 50,8% والذكور 49,2%. كل الحالات من السعوديين ما عدا حالة واحدة. كل الحالات ظهر عليها الطفح الجلدي والحرارة وهناك 97 حالة أثبتت مخبريا. من الحالات كان هناك 57,6% لم يتلقوا أي تطعيم ضد الحصبة و 13,6% قد تلقوا جرعة واحدة فقط.
فيما يتعلق بالدراسة القطيعية الإسترجاعية، كان هناك 5447 طفلاً سجلوا من عام 2000-2005م، أي خلال 6 سنوات، منهم 12,8% لم يطعموا ضد الحصبة و 54,1% تلقوا جرعة واحدة فقط من التطعيم، بينما 33,1% كانوا قد تلقوا كامل الجرعات. وقد كان 50,7% لم يطعموا في الوقت المناسب، بل كان هناك تأخير في تطعيمهم. وجدت الدراسة ان مركز صحي الصبيخة أفضل مركز صحي في إعطاء التطعيمات، يليه مركز صحي جاش، أما المركز الأقل أداءا فكان مركز صحي الأمواه. لوحظ أن الأطفال المسجلين خلال عامي 2000 و2001 لم يأخذوا جرعة الثلاثي الفيروسي بشكل مناسب.
قد ترجع الأسباب في ظهور هذه الفاشية إلى نقص مناعة المجتمع، إنخفاض نسبة التطعيمات، زيادة الأشخاص القابلين للإصابة، إضافة إلى طبيعة مرض الحصبة وكذلك طبيعة اللقاح الواقي منها.
تمت التوصية على رفع مستوى التطعيم ودقة التوقيت في إعطائه خصوصا في منطقة الأمواه، تكثيف المتابعة من قبل الجهات المسؤلة عن التطعيم في منطقة تثليث، تقديم الشكر للمسؤلين في مركز صحي الصبيخة و جاش على جهودهم في التطعيم وحثهم على الإستمرار، و القيام بحملات لتطعيم الأطفال المسجلين عام 2000-2001م بالجرعة الثانية من لقاح الثلاثي الفيروسي.