As more and more people travel each year, the spread of infectious diseases via international travel presents an increasing challenge to disease control globally [1]. Travelers to mass gatherings (MGs) play a significant role in the spread of infectious diseases across international borders due to their unique travel patterns and behaviors [2,3]. An MG has been defined as an event involving large number of participants (≥1000 attendees) at a specific location for a specific purpose for a defined period of time [4]. Hajj pilgrimage to Makkah, Saudi Arabia, is a noteworthy example of an MG. With 2 to 3 million attendees from about 185 countries attending annually, it is considered to be one of the largest annual MGs in the world. The Ministry of Health (MoH) in Saudi Arabia requires that all pilgrims are vaccinated against meningococcal disease, and that pilgrims from endemic countries are vaccinated against polio and yellow fever (Textbox 1) [5,6]. Moreover, vaccines against influenza, pertussis, mumps, and measles are also recommended, as well as other infection control measures, including the use of face masks and hand hygiene. Health authorities in travelers’ countries of origin are also encouraged to provide health education to the pilgrims [5,6].

Pretravel health advice can play a crucial role in improving both travelers’ awareness about disease risk and compliance with preventive measures. General practitioners (GPs) and the internet have been reported internationally as the main sources of health advice for travelers to non-MG destinations [7-12]. However, the few studies which have investigated the sources of health advice among travelers to Hajj found that about two-thirds of Hajj pilgrims sought pretravel health advice [13]. In an Australian setting, most Hajj pilgrims (88%) receive the vaccines (eg, meningococcal, influenza, and other travel vaccines) from GPs and a small proportion receive them from other sources including hospitals, workplaces, and travel clinics [13,14]. No study has yet investigated the impact of pretravel health advice on Hajj pilgrims’ awareness of official health recommendations, compliance with preventive measures during Hajj, or incidence of illness symptoms such as cough, sore throat, rhinorrhea, fever, vomiting, and diarrhea. To this end, we conducted a prospective cohort study among Australian Hajj pilgrims, before and during the Hajj in 2015.

This study shows that travel agencies and GPs were the most commonly sought sources for pretravel advice. Hajj pilgrims who obtained advice from travel agents were more likely to be aware of the official health recommendations, receive recommended vaccines, use hand soaps, and wash their hands after touching an ill person during Hajj compared to those who sought advice from GPs.

This study showed that 42% (177/421) of pilgrims obtained pretravel health advice from professional medical sources; this was somewhat lower than a previous survey among Australian Hajj pilgrims in 2014, which showed that 66% of respondents sought pretravel advice from medical sources [13]. In this study, although GPs were the most commonly sought source of professional advice (169/421, 40%), a small proportion (8/421, 2%) of the respondents sought advice from specialist travel clinics. This contrasts with another Australian survey, which found that 24% of pilgrims sought pretravel advice from specialist travel clinics before Hajj 2014, indicating annual variation or a real decline in the use of specialist travel clinic services [13].

This study found that seeking advice from GPs appeared to have no significant positive impact on vaccination uptake or the use of preventive measures during Hajj. The role of the GP in travel advice is challenging; providing accurate and tailored travel advice during consultations can be affected by limited time and resources. Studies focusing on non–Hajj-related travel found that travel health practitioners and GPs with travel medicine training had higher knowledge of travel advice [17,18], and were more likely to provide written educational materials than primary care physicians without travel medicine training [19,20]. It is noteworthy that in a standard pretravel consultation setting, the common topics of pretravel health advice are travel vaccines (eg, against hepatitis A, typhoid, and yellow fever); malaria prophylaxis; and personal protective measures against insect bites, geographically endemic diseases, food- and water-borne illnesses, and sexually transmitted infections [20-22]. Airborne infections such as influenza, meningococcal disease, and measles, which are the most commonly identified infectious diseases during MGs including Hajj, require a special set of vaccines and preventive measures not typically considered for ordinary travelers [23,24]. Therefore, attempts should be made to encourage GPs and travel practitioners to remain up-to-date with the latest recommendations for specific MGs. This could be achieved by providing accessible educational programs for healthcare providers that are specific to MG travel medicine and coordinated with the timing of events [25]. Uniquely, this study found that not recognizing the need to seek pretravel health advice from medical sources was the main barrier to seeking professional pretravel advice. Therefore, Hajj travelers need to be informed that they need travel health advice and this advice should be sought at least 6 to 8 weeks prior to Hajj [26]. This could be achieved by launching awareness campaigns prior to Hajj about the importance of seeking health advice [27].

This study shows that over half of Australian pilgrims (244/421, 58%) sought health advice from nonprofessional sources, mostly travel agents (192/421, 46%). These results may be due to a high level of confidence in advice from travel agents, and family and friends who had previous Hajj experience, as was also demonstrated in a qualitative study among Australian Hajj pilgrims between 2009 and 2012 [28]. In addition, this study found that receipt of pretravel health advice from specialist travel agents (tour group leaders) was significantly associated with travelers’ health knowledge and behaviors, including being more aware of the health recommendations of the destination country and better compliance with preventive measures. A previous study among Australian Hajj pilgrims in 2014 found that those who obtained health advice from a Hajj travel agency were more likely to be aware of the emerging infectious diseases in Saudi Arabia and receive vaccines than those who did not [13,29]. Similarly, Barasheed et al [14] found that receiving advice from Hajj tour group leaders was the main motivator for the uptake of influenza vaccination among Australian Hajj pilgrims in 2012. Hajj is not the only travel situation where travelers seek advice from tour operators; there are reports of other travelers (eg, tourists, and travelers visiting friends and relatives) seeking advice from travel agents [7-9,11]. Therefore, supplying travel agents with up-to-date, culturally appropriate health information may improve the health awareness and uptake of preventive measures among travelers, including Hajj pilgrims.

In this study, only 35% (147/421) of pilgrims were aware of the annual Hajj health recommendations issued by the Saudi Arabian MoH. Awareness was lower than that found by a previous study that surveyed Australian Hajj pilgrims in 2014, in which 46% of respondents were aware of the health recommendations [13]. Similarly, another study found that only 23% of European attendees at the Union of European Football Associations (UEFA)’s EURO 2012 were aware of the recommendations regarding measles vaccination before the event [30]. This indicates that published official guidelines may not uniformly reach all pilgrims across the world. Importantly, there are no studies that have assessed the usefulness of the official information from health authorities regarding Hajj or any other MGs; however, this study found that awareness of the official health recommendations was, curiously, not associated with pilgrims’ compliance with preventive health measures.

The Saudi Arabian health authority requires that health authorities in pilgrims’ countries of origin provide health education to their pilgrims before the pilgrims travel to Hajj [5]. Several studies found that health education delivered to pilgrims is an effective way of improving their knowledge of infectious diseases as well as the uptake of preventive measures [13,27,31,32]. However, uptake of preventive measures, including vaccination, varies among pilgrims by country of residence [33,34]. For instance, influenza vaccine uptake rates among Australian, French, and Egyptian pilgrims in 2012 were 89%, 46%, and 19.7%, respectively [14,35,36]. Lack of knowledge (particularly of the availability of a vaccine) was the main barrier to vaccine uptake and the use of measures to prevent diseases among pilgrims [13,14,28,37]. Theoretically, health agencies assume that health recommendations will reach Hajj pilgrims through their home country health authority, via health care providers. However, there is no evidence to identify the pathway and link between the issue of the annual Hajj health recommendations from Saudi Arabian health authorities, and how these recommendations are delivered to Hajj pilgrims in their countries. In this study, we identified that Hajj travel agents play an important role in this pathway. More detailed knowledge of this pathway and the dissemination of health advice may improve the promotion of Hajj health recommendations and the uptake of preventive measures among Australian pilgrims.

To our knowledge, this is the first in-depth cohort study investigating the impact of receiving pretravel health advice on travelers’ health behavior during an MG. However, there are some limitations. First, the findings from this survey cannot be widely generalized; the collected data relied on self-reporting and the quality of the health advice could not be evaluated directly. A study of travel agents is needed to complement this study. To this end, we have undertaken a qualitative study among Australian tour operators that assesses their understanding, practice, and advice on infectious disease prevention at Hajj; this study will be reported separately. Second, the “during Hajj” survey, which was conducted consecutively over 6 days by using the same questionnaire diary, may have actually served as a daily reminder for the preventive measures. Third, this being a self-reported survey, it was not possible for us to validate the information the respondents provided; for instance, we could not check if the GPs recorded their pretravel consultations, as is typically done by a trained travel physician. Fourth, it is noteworthy that in this study we could not evaluate the difference in impact between those who sought pre-Hajj advice and those who did not seek advice because all participants obtained some sort of pretravel advice. Finally, travel agents with larger quotas and those with pilgrims from multiple ethnic backgrounds were targeted first, which may have led to some selection bias.

In conclusion, this study has uniquely identified that advice from travel agencies (tour group leaders) reached more travelers than that of GPs or travel health practitioners, and was more strongly associated with travelers’ positive health behaviors. Travel agents are more easily accessible, experienced, inexpensive, and sensitive to culture. However, they do not have specialist medical knowledge and their advice did not appear to result in decreasing the incidence of symptoms of Hajj-related illnesses. This could be potentially addressed by educating agents and tour operators on basic travel health needs.