Risk factors for heat exhaustion among pilgrims to Makkah, Saudi Arabia, 1415 H

Pilgrims to Makkah (Mecca) usually undergo strenuous physical effort during pilgrimage (Hajj) activities, especially during the journeys between Holy places and when they throw pebbles at Jamarat sites. Hajjis move from Mina to Arafat and then back to Mina through Muzdalifa (a 16 mile journey) within 24 hours; some of the pilgrims trek some or all of these distances. These trips could immediately follow another long journey by land from another city that could be hundreds of miles away from Makkah At the Jamarat sites Hajjis are exposed to an overwhelming crowd. As a result every year thousands of cases of heat exhaustion (HE) occur (Figure 1).

During the 1995 Hajj, (ambient temperature 18.0-43.20°C, relative humidity 1181%), we conducted a 1:1 matched case-control study to examine the role of some potential behavioral risk factors for HE. A case of HE was defined as weakness, vertigo, headache, gastrointestinal symptoms, with or without faintness and collapse; and rectal temperature between 36° and 41°C. Controls were randomly selected from other Hajjis on the last day of Hajj. They were matched by age and sex. Hajjis who escorted a case of HE or shared the same tent or bus with him were excluded. Patients (N=97) and controls were interviewed to ascertain use of umbrellas, means of transportation between holy places, lodging, frequency of drinking fluids and beverages, and knowledge about heat-associated illnesses (HAI).

Cases of HE (mean age in years+SD=39.4 +16.3, range =14-78) constituted 20 different nationalities, mainly from countries in the Middle East. About half of the cases (51.5%) were residents of Saudi Arabia. Cases were admitted to the hospitals throughout the day as early as 6:45 A.M. and as late as 11:25 P.M. However, about one third of the patients (34.7%) were admitted before noon, a third between 12:00 noon and 4:00 p.m. (33.7%), and the last third was admitted thereafter. Most patients were brought to the hospital by ambulance (N=69, 71%), 19 (19.6%) by other pilgrims, and only nine patients (9.3%) walked in the outpatient clinics unaided. Male-female sex ratio was 4:1.

The main symptoms of the cases were headache (76.3%), dizziness (55.7%), muscle cramps (42.3%), malaise (35.1%), anorexia (35.1%) and nausea (33.0%). Eighty patients (82.5%) had no underlying chronic illness. The median systolic blood pressure was 120 mm Hg (inter-quartile range 110130 mm Hg), and the median diastolic pressure was 77.5 mm Hg (inter-quartile range 70-80 mm Hg). The mean pulse rate per minute (+ SD) was 94 + 12. The mean rectal temperature was 38.90+ 1.0° (median temperature 39° C); 2 patients had rectal temperatures of 36.6° C and 36.0° C, whereas 2 patients had temperatures of 41° C. All heat exhaustion cases received intravenous fluids. Seventy-four out of 97 cases of heat exhaustion (76.3%) were successfully treated with infusion of 500-1000 ml of normal saline only, or normal saline with 5% dextrose (23.7%). Antipyretics were given to 35 patients (36.1%). It took patients with heat exhaustion 4.04 (+ 1.97) hours to go back to Makkah to perform Twaf-el-Ifada compared with 2.48 (+ 1.66) hours for the controls (p< 0.05, t-test difference between 2 means).

Risk factors for HE included traveling by land to Makkah instead of flying (odds ratio [OR]=2.8, 95% confidence interval [CI]1.1-7.6), walking at least one of the four journeys between holy places (OR=3.5, 95% CI 1.7-7.5), not using an umbrella (OR=8.3, 95% CI 4.117.1), not staying in a tent or a building in Mina (OR=2.2, 95% CI 1.1-4.1), and being at landmarks in: Mount Jabel-al-Rahama (OR=2.5, 95% CI 1.2-5.3) or Namira Mosque (01t=3.1, 95% CI 1.2-8.7), losing their way in Mina (OR=39.3, 95% CI 5.8 652), taking light or no meals (OR=4.0, 95% CI 2.1-7.6), and early stoning of Jamarat (p<0.05 Chi-square for linear trend). Patients paid less for beverages in the 24 hours prior to hospitalization, and drank less water than controls during their movements between holy places (p< 0.05,t-test between 2 means). In the last 24 hours prior to hospitalization, cases (N=83) spent 5.2 SR (+ 5.95 SR) to purchase water or other beverages, whereas controls (N=80) spent 6.92 SR + 4.42 SR (p< 0.05, t-test difference between 2 means). Receiving free packs of ice-cold water or beverages was protective against HE (OR=0.37 95% CI 0.2-0.7). Chronic underlying illnesses, and educational level were not associated with HE. Only 22-26% of Hajjis knew about heat-associated illnesses.

Heat illnesses comprise a group of clinical conditions in which the temperature regulatory mechanism and associated physiological systems are unable to adapt efficiently to the stresses imposed by the surrounding conditions at high temperature.[1] Because the body is 25% efficient in translating calories generated from intense exercise into external work, 75% of all metabolic energy is converted into heat. The thermal burden of exercise is directly proportional to the intensity of effort. The majority of the heat load is lost through radiation, conduction and convection (65%), evaporation from the skin and lungs accounts for 30%; only minor loss through urine and feces (5%)[2]. 0vercrowding impedes dissipation of generated heat load.

Over two million Muslim pilgrims are at risk from HAI when they perform the annual pilgrimage (Hajj) to Makkah in hot weather. HAI are the leading cause of hospitalization during Hajj.[3,4]. The sudden short-term influx of unacclimatized religious visitors of diverse nationalities make risk factors for HAI seen at the Hajj more varied2. In the last three years 70-75% of all admissions made during the five days of Hajj were due to heat exhaustion only (Figure 2)[5].

The burden of HE during Hajj can be reduced by promoting many healthy practices; e.g., wider distribution of free packs of ice-cold water to Hajjis. Constructional changes and organization in the holy places to facilitate movements of Hajjis and providing shady areas would be beneficial. Health education programs, especially for domestic Hajjis, remains an important indispensable component in the institution of control measures. Hajjis must be encouraged to use umbrellas.