Keratoconjunctivitis outbreak in Al-Jubail, Saudi Arabia-April 2003

On 26/4/2003 an increase in keratoconjunctivitis cases was reported in the industrial city of Jubail, which is about 100 km north of Dammam in the Eastern Province. Most of the cases were school children. The Objectives of this study were to evaluate the existence, magnitude and distribution of the outbreak, to identify risk factors responsible, and to find practical solutions for controlling this outbreak and prevention of similar events in the future.

All cases reported to Ministry of Health in Riyadh were reviewed and all the sources visited to ascertain the number of cases including Health Affairs Department in Dammam, Health services and Schools of the Royal Commission of Jubail. A 1:1 case€”control study was conducted. A confirmed case was defined as any person living or working at Jubail industrial city from 12/4/2003 and having at least two of the following symptoms: red eye, eye pain, edema, excessive tearing, photophobia or foreign body sensation; examined and diagnosed by the ophthalmologist. Controls were chosen mainly from the school student population who didn't fit the case definition. Sampling was simply random from the school students and the ophthalmology clinic visitors. Questionnaires were filled either by direct interview or by telephone. Six random scrub specimens from the cases were sent to King Faisal specialist hospital for analysis. Air pollution levels in the residential area were reviewed.

The total number of reported cases till the end of April 2003 was 198. Males were 160 (83%) and females 38 (17%). Cases were registered from 25 schools in Jubail; 167 (84%) were from intermediate school or the final 2 years of primary school. 98% of cases were Saudis. All schools had standard buildings where the class was 6x 8 m, well ventilated and occupied by not more than 20 students, spaced from each other by about 1 m. All houses were new, clean and spacious with good sanitation.

The total case €” control study sample was 240; 120 cases (63% from the total number of reported cases) and 120 controls. Among cases there were 102 males (85%) and 18 females (15%). 88 cases (75.9%) were in the 10-20 year age group and the mean age was 14 years. Al-Khaleej intermediate school for boys, where the first case appeared, had the highest number of cases 38 (35%) out of 108 male cases. Al-Deffi district, which had 3 adjacent schools, had the highest number of cases 92 (76.7%). Red eye was the predominant symptom among cases (100%) followed by eye pain and edema.

The index case was an intermediate school student from Al-Khaleej school, but he had already left the school and moved with his family to an unknown location. 28 (23.3%) of the cases reported contact with ill individuals at home, and 90 cases (75%) reported contact with ill individuals at school before onset of symptoms. Males were at higher risk of getting the disease than females (OR=1.13, 95% CI=0.14-1.88). There was no association between younger age (below 20) and getting the disease (OR=0.11, 95%CI= 0.11-1.57). Acquiring infection by contact with ill people at home was about 50% higher than from other places, but the association was not statistically significant (OR=1.52, 95% CI=0.76€” 3.05). Acquiring infection from school contacts was associated with a lower risk in comparison to contact in other places (OR=0.36, 95%CI = 0.17-0.78) and the association was statistically significant. 47 cases (39.2%) had more than 8 members living in the same household. The association between number of family members and acquiring infection was higher with larger families (OR=1.15, 95% CI=0.66-1.99), and there was also an association between the number of bedrooms in the household and acquiring infection (OR=1.85, 95%CI=0.69-5.05) but both associations were not statistically significant. The only statistically significant association was between lower level of education (below secondary school) and acquiring infection (OR=2.03, 95%CI=1.08-3.84). Air pollution records were found to be within the usual levels in the residential area.

Stratified analysis showed that age and g ender did not confound the o b-served associations between the variables (contact with ill students and education level) and acquiring infection. Also, they were not effect modifiers.

The epidemic curve (Figure 1) shows a sharp increase in the number of cases on 14/4/2003, then a slow decline from 15/4/2003 and afterward, which may be due to the long communicability period of the disease (up to 14 days). The fall in the number of cases at the end of the period may be attributable to the control and preventive measures applied at that time in the form of isolation of sick students or effective health education on the disease and its complications. We cannot elaborate on the incubation period in this epidemic curve because the index case could not be contacted.

Epidemic keratoconjunctivitis (EKC) is a type of adenovirus ocular infection and is one of the most common causes of acute viral conjunctivitis. It is highly contagious and has the tendency to occur in epidemics.[1] EKC has unique clinical features, producing a sudden onset of acute follicular conjunctivitis The ocular symptoms are mainly sudden onset of irritation, soreness, red eye, photophobia, foreign body sensation, and excessive tearing. In more severe cases, patients can present with ocular and periorbital pain and decreased visual acuity. Symptoms tend to last for 7-21 days. The fellow eye tends to be involved in more than 50% of the cases within 7 days of onset. Both membranes and pseudomembranes can occur in EKC with a distinguishing corneal involvement that ranges from diffuse, fine, superficial keratitis to epithelial defects to subepithelial opacities.[2] Often, a recent history of an eye examination or exposure within the family or at work is present.[3] The incubation period is 2-14 days, and the person may remain infectious for 10-14 days after symptoms develop. Diagnosis is mainly clinical. Treatment is mostly symptomatic (cold compresses and artificial tears). In severe cases, mild topical corticosteroids can be used, especially for the subepithelial opacities, iritis or pseudomembranous conjunctivitis.[4] EKC is a self-limiting disease, tending to resolve spontaneously within 13 weeks without significant complications. In 20-50% of cases, corneal opacities can persist for a few weeks to months (rarely up to 2 y).[1,2,3] No gender predilection exists. The infection is more common in adults, but all age groups can be affected.

Because of low, natural immunity against adenovirus in the general population, every individual is considered susceptible to infection. EKC epidemics tend to occur in closed institutions (eg, schools, hospitals, camps, nursing homes, workplaces). Direct contact with eye secretions is the major mode of transmission. Other possible methods of transmission are through air droplets and possibly swimming pools. Many epidemics have also been initiated in ophthalmology outpatient clinics by direct contact with contaminated diagnostic instruments.[4] Despite extensive literature search there was no documented EKC outbreak in Saudi Arabia in the literature.

In this outbreak, about 62% of the total number of cases appeared in 3 adjacent schools at Al-Deffi district where the index case appeared and the epidemic started. The rest of the cases spread in small and discrepant rates in the other 22 schools outside and at the peripheries of Al-Deffi and most of them were secondarily infected patients through household contact with the primary cases of Al-Deffi schools.

Crowds at schools seem to be an important risk factor for transmitting the disease, which is most probably a contagious viral infection, but this risk factor was not statistically significant. Among all risk factors were investigated in this study, low level of education appears to be the only significant risk factor that might have attributed to this outbreak.

It was recommended to intensify health education about the disease and its complications, modes of transmission and preventive measures, using all available methods from simple paper bulletins distributed to the targeted places (schools, eye clinics and optic shops), to bulletins through other media if possible; Active surveillance to detect the cases as early as possible; placing emphasis on the surveillance system and advising health workers with its importance and to train them on making communiqués in the allocated forms and sending them to the specialized authorities in the definite time.