Brain-Eating Amoebae in the United Arab Emirates?

Abstract

Given the warm climate, excessive water-related recreational activities, and large Muslim population practicing ablution, it is surprising that primary amoebic meningoencephalitis is not reported in the United Arab Emirates. In a medical district, up to 43% of meningitis cases did not determine the causative organism, suggesting that cases likely go undiagnosed.

Naegleria fowleri is an opportunistic protozoan pathogen that is well-known to produce fatal brain infection referred to as primary amoebic meningoencephalitis.¹ It is one of the deadliest parasites known to humans, which if contracted, will lead to disease. It is disturbing that the mortality rate has persisted well over 90% in spite of the improvements in antimicrobial therapies and supportive care. It enters the human body via the nasal route, latches itself onto the nasal epithelial cells, and then crawl upward along the olfactory nerves (cranial nerves related to smell that connect the nasal mucosa to the forebrain).¹ Migration along this route leads to N. fowleri entry in the central nervous system (at the base of the brain) via the porous cribriform plate. In the nasal cavity, N. fowleri produce hydrolytic enzymes that digest mucus/proteins to avoid trapping and phagocytose materials/cells by formation of food cups (also known as amoebastomes) to fulfill its nutritional requirements. The result is severe inflammation of the brain tissue, often resulting in death within days of contracting the parasite.¹ The severity of the disease and associated clinical manifestations are similar to bacterial meningitis with fever, vomiting, headache, nausea, and stiff neck that can lead to misdiagnosis and inappropriate chemotherapeutic interventions.¹ The risk factors in contracting N. fowleri are as follows:

• (i)Swimming in pools, lakes, canals, bathing, hot springs, and other water-related recreational activities such as water skiing, tubing behind a boat, or hose water on slip-and-slide toys.
• (ii)Nasal cleansing with neti pots to deliver relief to sinusitis patients.
• (iii)Ayurvedic practice known as “jala neti”.
• (iv)Ritual ablution.¹

Although nasal cleansing stimulates good sinus and nasal health, it can only be effective if water used is disinfected, filtered, or boiled effectively. Given the widespread use of these practices globally, it is highly likely that a sizable number of patients affected by primary amoebic meningoencephalitis are likely unreported or misdiagnosed. Given increasing outdoor activities and global warming, there is an urgent need for awareness among clinicians and within the community.

As free-living amoebae consume organic matter and bacterial populations, they are widely distributed globally and have been isolated from various environments.^1,2N. fowleri have been retrieved in both temperate and tropical climates worldwide.² Furthermore, the amoebae are generally found in any fresh water, such as lakes, rivers, ponds, drainage ditches, or any other water that may be exposed to soil. Notably, the amoebae have a preference for warmer climates and grow well in soil and warm fresh water.² Hence, it is also frequently found in hot springs or in localized areas where warmer water may be discharged into lakes, for example in the case of industrial water discharge.² Being thermophilic, it thrives in waters with temperatures ranging from 24–46 °C. Plumbing and water heaters harbor amoebae such as N. fowleri. Under these conditions, N. fowleri multiplies rapidly.^1,2 It can infect people and animals when warm fresh water containing N. fowleri goes through the nose via water-related activities mentioned above (see abstract graphic). In recent years, there has been an increasing number of cases reported from the South Asian region such as Pakistan and India as well as in the southern states of the United States.^1,2 These are likely attributed to increased awareness, global warming, and increasing outdoor water-related recreational activities. More recently, ritual ablution in Muslims is considered as an additional and important risk factor in contracting this devastating infection.¹ The purpose of ablution is to cleanse the face, mouth, ears, nose, arms, and feet five times a day. One of the steps involves taking water into the nostrils for cleansing. Some people push water vigorously into the nostrils despite it not being required as part of the ablution process. Rather, the purpose of ablution is to decontaminate the body, which has clear medical advantages, but lack of availability to clean water can lead to this infection.¹

Notably, to our knowledge, there is not a single case of primary amoebic meningoencephalitis due to N. fowleri reported in the United Arab Emirates (UAE). This is unusual, especially in view of the warmer climate conditions, frequent use of swimming pools, water-related activities, the large Muslim population that performs ablution, and use of water storage tanks and water reservoirs, especially in remote/disadvantaged areas. Moreover, the issue of water is of concern in arid and semiarid environments.³ In the UAE, fresh water is usually delivered from desalinated water or groundwater obtained from wells; nonetheless, the use of both has limitations as desalinated water is costly. Supplies of groundwater are limited by the total reservoir capacity.³ In addition, in remote areas, fresh water is usually transported via tanks and stored in plastic or metallic reservoirs for domestic usage. Furthermore, it is common practice that in some regions of UAE, water supplies can encounter interruption at times, and water storage tanks are employed. Usually, in residential homes there are two large water tanks, with one situated at the ground level that contains treated water. The second tank is positioned on the roof and water is pumped from the ground level to this upper level tank. These tanks are often old and may not be frequently cleaned.⁴ A recent study carried out in the emirate of Sharjah revealed that bacteria coliforms were present in water from residential homes, including Klebsiella, Enterobacter spp., and Serratia, and this is of concern as the bacterial contaminants discovered in these tanks are presumed to originate from the environment. It is likely that other contaminants may be present as well as amoebae, which were not evaluated in this study.⁴

Thus, it is surprising that there are no reports of primary amoebic meningoencephalitis due to N. fowleri in the UAE. In a previous study undertaken in the district of Al-Ain, in 10% of cases that were clinically diagnosed as meningitis, no specific microbial etiology could be elucidated. Furthermore, an additional 33% cases of meningitis were presumptively attributed to bacterial pathogens devoid of the final determination of the causative agent.⁵ All in all, in 43% of cases, the causative agent was not determined but presumed to be microbial in nature. Given the similarity in clinical symptoms of meningitis and primary amoebic meningoencephalitis, it is possible that cases go undiagnosed. Hence, it is imperative that N. fowleri is suspected as an additional pathogen. Furthermore, there could be a lack of diagnosis at premortem, and the fact that autopsy is often not performed could lead to under-reporting. Overall, there is a need for research studies to determine the prevalence of N. fowleri in various environments in the UAE as well as increased awareness of this devastating infection among public health officials and the medical community.

Author Contributions

R.S. and N.A.K. envisioned the concept amid critical discussions with T.H.I. and M.K. R.S. reviewed the literature, and N.A.K. prepared the first draft of the article. R.S. finalized the manuscript. All authors contributed equally to the manuscript and will act as guarantors.

The authors declare no competing financial interest.