He Cryptosporidium It is a microscopic protozoan which takes the public health services of half of Europe upside down. The incidence of this parasite of the digestive system, which usually causes mild gastrointestinal symptoms – although they can be serious in babies due to dehydration and pose a life-threatening risk for immunosuppressed people – has skyrocketed in much of the continent without experts finding a solution. a single cause that explains it. Spain has recorded 2,940 confirmed cases so far this year, a figure that multiplies the 805 registered in all of 2022, of which 121 have had to be hospitalized, according to data from the National Epidemiology Center. A trend similar to that observed in United Kingdom, Ireland, Netherlands and Luxembourgaccording to recent publications from the European Center for Disease Control and Prevention (ECDC).
The detection of the parasite in recent weeks in more than 600 British and Irish tourists after spending their holidays in Spain has activated European alert systems, although it has also raised some misgivings among Spanish researchers and public health officials. The reason is the way in which countries like Ireland have presented the rise in cases, pointing out Spanish towns like Salou (Tarragona) as a source of infections in which it is advisable “not to consume drinks with ice” and “check if the water in the faucet is treated”, among other measures. “Smell it to detect the smell of chlorine bleach,” can be read in a statement from the public health of that country.
In reality, health officials from two autonomous communities who are familiar with epidemiological investigations point out, “the focus of this type of contagion is often the hotel pools, where dozens or hundreds of people of the same nationality coincide, some of whom arrive infected and where all hygiene measures are not always respected, which favors outbreaks among tourists themselves.” These sources highlight that “cryptosporidiosis [la enfermedad causada por el parásito] “It is a global issue and the way in which the problem has sometimes been raised is far from reality and does not focus on the measures that really help to avoid infections.”
An example, widely cited among specialists, is the recommendation of the Irish authorities that, in the case of diarrhea, “do not enter swimming pools for two days after symptoms have disappeared“, when what is established in these cases is to avoid bathing for 14 days.
The Cryptosporidium are actually a large genus of protozoa that affect dozens of species of mammals, birds, reptiles… Although each parasite has a greater affinity for a specific species, jumps between them are frequent. The protozoan reaches the host’s intestinal epithelium through consumption of contaminated water or food. There, after several phases, the parasite multiplies and forms tens of thousands of oocysts that are released into the environment through feces. These oocysts are often resistant to the levels of chlorine used in drinking water networks and swimming pools. This and the fact that only a dozen of them are enough to make a person sick explain the frequency and magnitude of the outbreaks.
Infections to humans usually occur in two ways. The first is due to environmental contamination of drinking water networks or facilities such as swimming pools, a process that is favored by episodes such as torrential rains. According to Isabel de Fuentes, a parasitology researcher at the National Center of Microbiology of the Carlos III Health Institute, in these cases “water treatment systems and plants may be overwhelmed” or there may be a carryover effect of oocysts dispersed in the environment or on farms. livestock.
This seems to have been the cause of the large outbreak that has occurred in recent months in Tarazona (Zaragoza), with more than 500 cases and whose specific origin is still being investigated. The largest epidemic of its kind collected in the scientific literature occurred in April 1993 in Milwaukee (United States) and affected more than 400,000 people—a quarter of the population of its metropolitan area—, with 69 deaths, when the drinking water network was contaminated.
The second major form of contagion is between people and this usually occurs most of the time in closed water facilities, explains Jacob Lorenzo-Morales, director of the protozoa laboratory at the University Institute of Tropical Diseases and Public Health of the Canary Islands and with experience in investigating outbreaks of Cryptosporidium. “Swimming pools and water parks are a recurring source of outbreaks, but the fact that they happen has more to do with the hygiene of some users than with the cleanliness of these spaces, which are subject to strict maintenance regulated by regulations,” he explains.
“If someone does not clean themselves well after going to the bathroom or uses a swimming pool after having diarrhea without respecting the recommended 14 days, they will release thousands of oocysts into the water. If one or two people do it, there will be no problems due to chlorine and dispersion. But if there are several, or an infected baby is in the water with dirty diapers, or similar events, the pool will be contaminated,” describes Lorenzo-Morales.
The Center for Coordination of Health Alerts and Emergencies (CCAES) of the Ministry of Health confirms in writing that this year “there has been an increase in cases of Cryptosporidium notified by the autonomous communities and also by Ireland and the United Kingdom.” The Center’s response adds that “the majority [de casos y brotes] They are associated with swimming pools and recreational waters, mainly in summer.” Given the increase detected, Health “has created a working group with the communities to improve environmental surveillance of this protozoan.”
The Irish authorities published the statement on October 13 in which they warned of an increase in cases of “cryptosporidiosis, a potentially serious stomach ailment, reported in areas of Spain, particularly in Salou, in Catalonia” and offered “precautions to follow with food and water to help stay safe.” The data offered by the country’s Health Protection Surveillance Center indicated that since August 64 cases linked to Salou had been diagnosed, with five hospitalizations, and added that this year the country has registered more than 650 cases of the disease, 30% more than in 2022.
This information, however, did not specify how many cases or outbreaks have occurred in the country in people who have not traveled abroad, a relevant fact if one takes into account that the latest annual report on the disease in Europe from the ECDC – published in 2021 with data from 2018— places the country as the second with the highest incidence of cryptosporidiosis in the EU. An accounting that, however, experts recommend taking with caution because there is a significant under-reporting of the disease and not all countries have the same levels of surveillance or send the same data to the agency.
An investigation still underway by researchers from the United Kingdom and whose first results have been published in Eurosurveillance, the ECDC scientific journal, describes an “unusual increase” in cases of cryptosporidiosis in the country and does distinguish between cases acquired in the United Kingdom and abroad. Between August 14 and October 1, a total of 2,411 cases of the disease have been diagnosed in the UK. Of them, just over half of those with information available had reported a trip abroad, 46% of which—approximately a quarter of the total, about 600—to Spain.
This leads the authors to state that the data “suggests that many cases may be related to international travel, especially to Spain and other Mediterranean countries,” although they also admit that “at this stage of the investigation it cannot be excluded that other sources , for example contaminated food, are contributing to the excess” of diagnoses. In any case, the researchers insist on “the importance of avoiding the use of swimming pools while [la persona] suffer symptoms [gastrointestinales] and in the 14 days after its end.”
From reading the work another conclusion can also be drawn: that the risk is not so much in traveling, but in bathing in contaminated pools. “That half of those infected in the United Kingdom have not traveled outside the country is significant,” highlights De Sources.
This expert considers that summer trips and activities – during which tourism in Spain has risen sharply – are important keys to take into account when interpreting the published data. “People travel more and swim more in pools in summer, so it is logical that more outbreaks will occur when and where this happens. Without a complete and detailed study of the health situation and genotypes, before and after travel, it cannot be stated whether the origin of the outbreaks is in Spain or if the parasite has traveled with tourists from their countries of origin,” he concludes. she.
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