Sacred journeys and pilgrimages: health risks associated with travels for religious purposes

European/Asian pilgrimages

Christian pilgrimages occur on all continents except Antarctica. They encompass visits to the burial sites of Christian saints and places where miracles or apparitions are believed to have occurred. Table 1 contains data on health risks documented at the Vatican,¹¹ Lourdes,^12–14 Shrine of Fatima,¹⁵ Santiago de Compostela,^16,17 Medjugorje,¹⁸ Church of the Holy Sepulchre,¹⁹ as well as some other pilgrimages. Christian MGs in the USA, France, Germany and Austria have been associated with several outbreaks of measles and mumps.²⁰

World Youth Day and papal visits

The Catholic Church’s World Youth Day (WYD) is a MG of young people held over ~6 days approximately every 3 years since 1984, with the Pope usually in attendance. The largest attendance reported was 5 million people in Manila, The Philippines, in 1995. The WYD event of 2008 held in Sydney, Australia, was attended by 223 000 young pilgrims from 170 different countries. Masses with Pope Benedict XVI were attended by up to 400 000 people.²¹ Influenza types A and B were identified in ill pilgrims: influenza A was most frequently isolated from Australian and German pilgrims, whereas influenza B was most frequently isolated from pilgrims from the Solomon Islands, Papua New Guinea, Australia and North America.²² The epidemiological and virological data gathered during WYD2008 highlighted the complexity of influenza outbreaks in MGs, with six distinct viruses identified among pilgrims during 1 week. Different viruses circulated in different pilgrim groups suggesting that infection was not random but influenced by country of origin and travel. The risk was not limited to MG participants, but increased influenza A and B activity was identified in all Australian states.^23,24 Papal visits to various destinations resulted in a variety of medical emergencies, some associated with the climate,^25,26 other with stress resulting in hypertension and headache.²⁷

Latin American pilgrimages

Approximately 40% of the world’s 1.37 billion Catholics live in Latin America and the Caribbean,²⁸ with the bulk residing in Brazil (145 million) and Mexico (123 million). Catholic traditions drive millions of devotees to regional and international pilgrimages where miracles are believed to have occurred.²⁹  Table 2 contains some of the known health risks.

The National Shrine of Our Lady of Aparecida in Brazil³⁰ has an on-site clinic that provides health care to ~25 000 pilgrims annually with 8% requiring a higher level of care. Non-communicable conditions, obstetric and trauma cases were the most frequent presentation, but vector-borne diseases such as dengue are of concern.^31–35 The Basilica of Our Lady of Guadalupe in Mexico City is among the most visited Catholic sites in the world. About 11 million local and international visitors gathered around the shrine during the main festivities in December of 2022.^36,41 Between 3000 and 8000 patients are seen annually. Reasons for consultation are available from similar pilgrimages in Mexico and include musculoskeletal, gastrointestinal, cardiovascular and metabolic conditions.^37,38 Thousands of pilgrims reach the Basilica walking hundreds of miles from different Mexican states and traffic accidents involving pilgrims walking on highways are commonly reported. Foreign pilgrims, including Mexican nationals coming from other countries, may experience health conditions common to other types of travellers including acute diarrhoea and dengue fever. Gastrointestinal infections are common in Mexico and food and water precautions may partially mitigate the risk. The Iztapalapa Passion Play in Mexico has been associated with the spread of the 2009 H1N1 influenza pandemic,³⁹ and the 5-day Lord of Miracle procession in Peru is a large gathering where non-communicable diseases and injuries are reported. Increased risk for dengue fever is likely given recent large outbreaks in Lima in recent years.⁴⁰

African pilgrimages: Zion Christian Church

In 2020, Independent African Churches (IACs) were estimated to have 243 million members out of a population of 1.14 billion in Sub-Saharan Africa.⁴² These terms refer to ‘A church which has been founded in Africa by Africans primarily for Africans’,⁴³ which have assimilated African traditions into their practices and beliefs.⁴⁴ Some have specific pilgrimages, such as the 3-day 80-km walk from Ebhohleni to the Holy Mountain at Nhlangakazi undertaken by members of the Shembe Church in South Africa’s KwaZulu Natal province.⁴⁵ Healing is an important component of many IACs and pilgrimages are often undertaken to complement African traditional medical practices and western medicine, a practice termed ‘medical pluralism’.⁴⁶

The Zion Christian Church (ZCC) has an estimated membership of 20 million.⁴³ Two pilgrimages take place annually to its headquarters based in Moria in the Limpopo province of South Africa; the largest occurs during the Easter weekend with pilgrim numbers estimated between 5 million⁴⁷ and 12 million.⁴⁸ Undertaking a pilgrimage is considered as part of a duty.⁴⁹ The ZCC is noted for its tightly knit structures and a paucity of information is available about health structures and outcomes.⁴⁸

Attendees are overwhelmingly from South Africa (95%) with Zimbabwe (2%), Malawi (1%), Botswana (1%) and Namibia (1%) making up the balance.⁵⁰ About 98% are repeat visitors with an average age of 30 years.⁴⁹ Travel by pilgrims to Moria is exclusively by road, and one study alluded to 99% of respondents being concerned by the traffic and travel issues.⁴⁹ In March 2024, 45 Botswana citizens died in a bus accident en-route.

Despite the large numbers, no stampedes, infectious diseases outbreaks or other health hazards have been documented since the 1910 inception of the church.⁴⁷ Pilgrims with tuberculosis seeking healing have been reported,⁴⁵ but no secondary cases. Sanitation programmes are run if cholera is reported in areas from where pilgrims come. Some pilgrims come from malaria endemic areas, but no cases of imported or odyssean cases have been reported. An on-site clinic and hospitals in the nearby town of Polokwane provide medical support as needed.

Hajj

The Hajj is one of the largest annually recurring MGs in the world and has been extensively documented, including heat-related illnesses associated with it.⁵¹ During several specific holy days of Hajj (from the 8th to the 12th of the Hajj month based on the Islamic lunar calendar), pilgrims throng in periods of intense supplication localized at specific small sites (Mina, Arafat and Muzdalifa) and experience a number of public health challenges in the pursuit of spiritual redemption.

Hajj is unique in several respects. Its recurrence at the same sites annually contrasts with its ever-changing seasonal dates because of the Islamic lunar Calendar. As a result, Hajj falls 10–11 days earlier each year, introducing annual seasonal and climatic change. Environmental health risks may therefore also be fluid: sometimes Hajj coincides with influenza season, for instance, magnifying public health risks.^52,53 These risks may potentially worsen as infectious disease profiles change in the context of unchecked global warming.⁵⁴ Hajj has gone through the COVID-19 pandemic period, and to safeguard the wellbeing of the pilgrims, the Hajj authorities reduced the number of pilgrims significantly, limiting it to national pilgrims. This was in addition to enforcing strict infection control and prevention guidance and making the COVID-19 a mandatory requirement for hajj when it became available.^55–57 Hajj attendees (often known as Hajjes) are extraordinarily diverse in age, pre-existing health status, nationality and country of origin.

Hajj is also variable in terms of crowd behaviour.⁵⁸ Worshippers are both static and dynamic. Because all Hajjes travel as part of small informal groups, there remains some order in what could otherwise deteriorate into individual chaos. Furthermore, this flexibility safeguards Hajj at the most pressured points, which could otherwise become treacherous on occasion. Foremost being the Jamarat rituals. Table 3 contains some of the documented infectious,^59,60 heat illness^61–63 and trauma⁶⁴-related health risks associated with Hajj.

Umrah

Umrah is termed the minor pilgrimage performed by >10 million annually: Table 4 indicates the differences between Hajj and Umrah.⁶⁵ Compared to Hajj, there has been limited focussed research on Umrah, and most of the available studies did not split Umrah and Hajj data.

Following the large intercontinental outbreak of meningococcal A after the Hajj of 1987, there were several smaller outbreaks of meningococcal disease (mostly A) in Makkah that affected Umrah pilgrims till 1997.⁶⁶ In 1992, there was a sizeable outbreak of meningococcal disease with 102 confirmed cases and 80 suspected cases; 59% of confirmed cases were Umrah pilgrims with a case fatality rate of ~15%.⁶⁷ Meningococcal carriage rate among Umrah pilgrims has been low (between 0.5% and 1.3%)—in a 2001 study conducted among returned Singaporean Umrah pilgrims, the carriage rate was found to be significantly lower compared to Hajj pilgrims (1.3% vs 1.7%, P < 0.001).^68,69 There were reports of cases in pilgrims and contacts in May 2024 linked to unvaccinated pilgrims.⁷⁰

In 2019, a high prevalence (34.6%) of influenza-like illness was reported in a study of 616 multinational Umrah pilgrims.⁶⁸ In an Iranian study conducted in 2013–15 involving 712 Umrah and 1355 Hajj pilgrims, the proportion of influenza was significantly higher among Umrah pilgrims compared to Hajj pilgrims (27% vs 4%, P < 0.001)^71,72; however, a syndromic comparative study conducted in 2021 involving predominantly Saudi Umrah and Hajj pilgrims (500 in each group) found the rate of respiratory tract infections to be significantly lower among Umrah pilgrims (2.2% vs 4.7%, P = 0.05).⁷³ A larger study conducted in 2022 involving 3862 Egyptian pilgrims who returned from Umrah or Hajj demonstrated a lower prevalence of SARS-CoV-2 infection among Umrah pilgrims compared to Hajj pilgrims (6.7% vs 9.9%, P < 0.001), whereas no significant difference was observed in influenza prevalence (11.7% vs 9.2%, P = 0.275).⁷⁴

In 2005, compared to pre-Umrah period, a higher prevalence of intestinal parasites was reported among residents of Makkah during post-Umrah period (73.8% vs 66.3%, P = 0.02). The most common parasites were Entamoeba histolytica/Entamoeba dispar (57.9%) and Giardia lamblia (6.0%).⁷⁵ In 2014 and 2015, 232 cases of imported malaria were reported among travellers to Makkah, including Umrah pilgrims.⁷⁶

Compliance with preventive measures was often suboptimal in Umrah pilgrims: a survey conducted in 2019 among 1012 multinational pilgrims found that 24% had not received any vaccinations (including the compulsory ones), and the majority of pilgrims (83%) did wash their hands with soap and water or sanitizers, whereas another comparative survey conducted in 2019 showed Umrah pilgrims’ compliance with the frequent use of alcohol-based hand rubs to be significantly lower than that of Hajj pilgrims (36.3% vs 53.0%, P < 0.001).⁷⁷

Arbaeen

The Muslim Arbaeen pilgrimage in Iraq is one of the largest annual religious MGs in the world, commemorating the martyrdom of Imam Hussein, the grandson of Prophet Muhammad.⁷⁸ The number of pilgrims has approached 20 million in the last years, most of them local, though a significant proportion come from >40 other countries.⁷⁹

This event draws mostly Shia Muslim to the holy city of Karbala and has become a symbol of unity, devotion and resilience among its participants.⁸⁰ It is marked by long walks of >80 km, covered in ~3 days, from the cities of Najaf or Basra, and culminates in a visit to the shrine of Imam Hussain in Karbala. Almost all the necessary services like provision of food, drinks, accommodation and sometimes even health services are provided by the civil society free of charge through the ‘mawakeb’ established by local residents.

It creates profound pressure on the public health in the country with potential threats to regional and global health.⁸¹ It can facilitate the rapid transmission of communicable diseases, including respiratory infections, gastroenteritis and vaccine-preventable diseases because of the close contact between individuals, crowded living conditions and inadequate sanitation facilities. Inadequate water and lack of hygiene can increase the risk of water-borne diseases. There is currently surveillance structures in place.⁸² Exacerbation of chronic non-communicable diseases is another threat facing pilgrims in this MG considering the walking for long distances, changing food regimens and inadequate compliance to medications.⁸³

Different types of injuries are not uncommon during this MG. Road traffic accidents are on top of injuries leading to a significant annual morbidity and mortality. Other reported injuries include burns, falls, stampedes and others.^84,85 Terrorist attacks are another type of threat, though this probability has dramatically decreased over the last years.

Organizing a gathering of such magnitude comes with its share of challenges. The Iraqi government, along with religious authorities, has implemented various measures to address these challenges. Syndromic surveillance during MG is among the strategies adopted to monitor and early detect outbreaks of significant communicable diseases.^82,86 Other measures included crowd control, medical facilities and security arrangements, with the aim to safeguard participants and ensure the smooth conduct of the pilgrimage.

Grand Magal de Touba

The grand Magal de Touba (GMT) is the largest annual Muslim event in Senegal, gathering 4–6 million pilgrims in Touba.⁸⁷ It leads to a privileged encounter with a personal spiritual guide and honouring the founder of the Mouridism order. Pilgrims come from across Senegal and the surrounding countries, as well as from countries outside Africa. The rituals last 1 day; however, pilgrims usually stay for several days.

With the exception of cholera outbreaks in 1973 and in 2004–06,^88,89 most available data about diseases at the GMT have been published during the last 8 years. Medical care is provided to pilgrims free of charge for 5 days.⁹⁰ Most of the available local public medical infrastructures are involved in the medical preparation for, surveillance of and response to the event. At least 5244 healthcare workers were mobilized during the GMT in 2018. The Ministry of Health set up 176 medical service delivery points, which included hospitals, health care centres and advanced medical posts.⁹¹

During the 2015 GMT, of the 32 229 patients who consulted health services in Touba and the surrounding area during the 5-day period of free medical coverage, the most common reasons for medical consultation were gastrointestinal symptoms (14%), respiratory and ear, nose and throat symptoms (10%), fevers of unknown origin (5%) and confirmed malaria (3%).⁸⁸ In a 2016 study conducted among 20 850 patients, the most prevalent symptoms were headaches (28.2%), gastrointestinal symptoms (22.0%), fever (17.2%) and respiratory symptoms (17.1%), and 2.4% had confirmed malaria.⁹² Prospective cohort studies conducted from 2017 to 2021 showed that 55% of pilgrims reported respiratory tract symptoms and 13% gastrointestinal symptoms.^93–95 A proportion of 18% of pilgrims acquired at least one respiratory virus, notably human rhinoviruses (10%) and coronaviruses (6%). The acquisition of respiratory bacteria was high (40%) notably Haemophilus influenzae (19%) and Streptococcus pneumoniae (14%). The acquisition of gastrointestinal pathogens was lower, with enteroaggregative Escherichia coli (19%) and enteropathogenic E. coli (EPEC) (11%) the most frequent. A clear association of respiratory symptoms with acquisition of viruses and S. pneumoniae was observed.

Cross-sectional studies showed that in patients with a cough, 63% tested positive for at least one virus, including influenza viruses (33%). A high positivity rate of bacterial respiratory carriage was observed for H. influenzae (73%), S. pneumoniae (51%) and Moraxella catarrhalis (46%). In patients with diarrhoea, 71% were positive, with high rates of bacterial carriage, ranging from 4% for Tropheryma whipplei to 45% for EPEC. In patients with fever, 32% had pathogens detected, including Plasmodium falciparum (21%), Borrelia sp. (6%) and dengue virus (5%).^96,97

Bishwa Ijtema

The Bishwa Ijtema is an annual Muslim religious mass gathering in Bangladesh.^98,99 The Ijtema takes place over 3 days and is held in two phases, a week apart. In 2024, the first phase of the Ijtema was held from 2 to 4 February, and the second phase took place from 9 to 11 February. An estimated 1.7–4 million, mostly local participants, attend, with about 50 000 foreigners from 50 countries having a specific reserved area.¹⁰⁰ The event includes collective prayers and sermons, with attendees striving to sacrifice worldly luxuries.

The Ijtema has its own permanent 160-acre site in Tongi on the outskirts of Dhaka. The logistics, management of the event and accommodation of attendees are co-ordinated by a central Ijtema management structure with teams of volunteers and crucial support provided by the Bangladeshi government. A large jute canopy is erected over the 1-km-long prayer ground. The physical limitation of the main site means that people often sit on roads, by-lanes and rooftops to get a better view of the proceedings.⁹³ The government implements safety and security arrangements including observation towers for members of the rapid Action Battalion to oversee the entire event and ensure security.

Health risks (both communicable and non-communicable diseases) pose significant public health concerns, particularly for older individuals and those with pre-existing health conditions. Respiratory infections as well as exacerbation of asthma are common in cold weather conditions. Vector-borne diseases like dengue and chikungunya are a cause for concern,¹⁰¹ as is the risk of water-borne diseases such as dysentery through contaminated water sources or improper handling of food and waste. More than 2000 cases of diarrhoea were treated in 2023.¹⁰²

To avert these risks, the government provides temporary hospitals and medical centres and deploys a significant number of medical and sanitation teams located at the Ijtema grounds. Tertiary hospitals are in close proximity to ensure accessible healthcare and transfer as needed. Many private social and religious organizations play a crucial role by offering free medical treatment round the clock.¹⁰³

Buddhist pilgrimages

Pilgrimage, from a Buddhist point of view, is a way of gaining merit by focussing one’s energies on visiting sacred sites, such as the four main places associated with the Buddha’s life: his birthplace in Nepal, and the places in India where he gained enlightenment, gave his first teachings and where he died. The Great Stupa in Boudhanath, Nepal, is another important pilgrimage destination, where hundreds of people per day circumambulate to gain merit. In addition, there are many places where great masters practised that are said to contain great blessings, or sacred mountains and lakes to visit and circumambulate. In this context, pilgrimage is a personal journey, although in popular destinations, they may encounter many other pilgrims along the way.

Mass gatherings, in the Tibetan Buddhist tradition, usually involve receiving ritual empowerments and teachings, such as the Kalachakra empowerment given by His Holiness the Dalai Lama, at which hundreds of thousands of pilgrims might attend for several days. But these are infrequent events, not regularly scheduled.¹¹⁹ The Wesak (or Wesak) Festival or popularly known as Buddha Day,¹²⁰ is one such event with the 2023 festival celebrated in Vietnam over 2 days, with representation of 13 countries and >70 000 Buddhists.

Jewish pilgrimages

The annual Lag BaOmer pilgrimage to Mount Meron in Israel falls on the 33rd day of the Omer: 49 days between the end of Passover and Shavuot. The annual gathering, which takes place at what is believed to be the gravesite of the second-century Talmudic sage Rabbi Shimon Bar Yochai, is the largest Jewish pilgrimage in modern times,¹²¹ with an estimated 250 000 persons attending overall and 100 000 present on-site during the peak hours.¹²²

The pilgrimage typically involves singing, dancing and lighting bonfires as a symbol of the spiritual light attributed to Rabbi Shimon. It is a joyous occasion marked by unity, prayer and celebration of Jewish heritage and tradition. The large crowd at the tomb of the rabbi pose risks of stampedes, overcrowding and accidents. In 2021, a stampede led to 45 deaths and 150 injuries. Bonfires pose a potential risk of fires spreading to other areas, as well as an increased risk of burns. Furthermore, smoke inhalation may increase the risk of bronchitis and worsening of asthma.¹²³ Weather-related incidents, depending on the season, infectious disease risks due to the crowds and mental health issues have also been considered.