Category Archives: Giardia

ECDC – Giardiasis (lambliasis) – Annual Epidemiological Report for 2019



In 2019, 18 004 confirmed giardiasis cases were reported in the EU/EEA. The EU/EEA notification rate was 5.2 cases per 100 000 population. The highest notification rates were reported in Belgium and Bulgaria. The EU/EEA notification rate was stable in the period 2015–2018, with a drop in 2019, the reasons for which have yet to be determined. The highest notification rate per 100 000 population was observed in the age group 0–4 years (16.5 for males and 15.0 for females).

Giardiasis is a common parasitic infection worldwide, caused by the protozoan Giardia lamblia (syn. G. duodenalis, G. intestinalis). The disease may be asymptomatic and self-limiting, or characterised by fatigue, bloating, acute diarrhoea and other chronic gastrointestinal symptoms. Infection occurs frequently via ingestion of cysts found in contaminated water (water-themed recreational activities, swimming pools or drinking water) or food, but person-to-person transmission may also occur, e.g. through sexual transmission.

Click to access giardiasis-%20annual-epidemiological-report-2019_0.pdf

Ireland – Wexford boil water notice impacting over 25,000 people could remain until middle of next week – Giardia


A boil water notice impacting over 25,000 people on the Wexford town public water supply could remain in place until the middle of next week.

Wexford County Council and Irish Water made the decision to implement the boil water notice with immediate effect on Wednesday evening, after samples taken from the Newtown Road Treatment Plant in town showed a detection of Giardia.

An emergency consultation with the HSE followed and the local authority took the decision to implement a boil water notice for an area covering the vast majority of Wexford town and right out as far as Taghmon.

The authorities say that they took the action “to protect the health of consumers” across Wexford. The consumption of water containing Giardia can cause diarrhoea, extreme abdominal cramps and gas. It is unclear if there’s been any official reports of people ill as a result of consuming the water, however, a few posted on social media complaining of these types of symptoms.

Research – Survey of the occurrence of Giardia duodenalis cysts and Cryptosporidium spp. oocysts in green leafy vegetables marketed in the city of Valencia (Spain)

Science Direct


The role of vegetables usually consumed without prior culinary treatment is known to contribute to the prevalence of foodborne diseases. Cysts and oocysts can contaminate food, which can then be the source of infection in humans. The aim of the study was to assess the occurrence of Giardia duodenalis and Cryptosporidium spp. (oo)cysts in green leafy vegetables marketed in the city of Valencia (Spain) combining parasitological methods, two real-time qPCRs and light microscopy. An experimental field study was conducted on 129 vegetable samples, 64 from conventional farms and 65 from ecological (organic) farms. The samples were washed with water, and the resulting solution after removing the vegetables, was subjected to 24-hour sedimentation. The concentrated sediment was used for the search for protozoa. A positive result by both real-time PCRs, or a positive result by one qPCR and confirmation by microscopy was established as a positivity criterion. Giardia duodenalis was detected in 23.0 % of the samples, and Cryptosporidium spp. in 7.8 %. G. duodenalis (41.5 %) and Cryptosporidium spp. (20.0 %) were more frequent in ecological crops. The high level of contamination detected in organic vegetables may be due to the type of fertilizers and the quality of the water used for their irrigation and reinforces the need to take extreme hygiene measures in vegetables that are consumed raw.

Research – Pathogens can hitch a ride on plastic to reach the sea

Phys Org

Microplastics are a pathway for pathogens on land to reach the ocean, with likely consequences for human and wildlife health, according to a study from the University of California, Davis.

The study, published April 26 in the journal Scientific Reports, is the first to connect microplastics in the ocean with land-based pathogens. It found that microplastics can make it easier for disease-causing pathogens to concentrate in plastic-contaminated areas of the ocean.

The pathogens studied—Toxoplasma gondii, Cryptosporidium (Crypto) and Giardia—can infect both humans and animals. They are recognized by the World Health Organization as underestimated causes of illness from shellfish consumption and are found throughout the ocean.

“It’s easy for people to dismiss plastic problems as something that doesn’t matter for them, like, ‘I’m not a turtle in the ocean; I won’t choke on this thing,'” said corresponding author Karen Shapiro, an infectious disease expert and associate professor in the UC Davis School of Veterinary Medicine. “But once you start talking about disease and health, there’s more power to implement change. Microplastics can actually move germs around, and these germs end up in our water and our food.”

UK – Estimating deaths from foodborne disease in the UK for 11 key pathogens



To estimate the number of deaths from foodborne disease in the UK from 11 key pathogens.


Four different models were developed using data from a range of sources. These included enhanced surveillance, outbreaks, death certificates and hospital episode statistics data. For each model, median estimates were produced with 95% credible intervals (CrI). The results from the different models were compared.


The estimates for foodborne deaths for each pathogen from the different models were consistent, with CrIs largely overlapping. Based on the preferred model for each pathogen, foodborne norovirus is estimated to cause 56 deaths per year (95% CrI 32 to 92), foodborne Salmonella 33 deaths (95% CrI 7 to 159), foodborne Listeria monocytogenes 26 deaths (95% CrI 24 to 28), foodborne Clostridium perfringens 25 deaths (95% CrI 1 to 163) and foodborne Campylobacter 21 deaths (95% CrI 8 to 47). The considerable overlap in the CrIs means it is not possible to make any firm conclusions on ranking. Most of these deaths occur in those aged over 75 years. Foodborne deaths from ShigellaCryptosporidiumGiardia, adenovirus, astrovirus and rotavirus are all rare.


We estimate that there are 180 deaths per year in the UK (95% CrI 113 to 359) caused by foodborne disease based on these 11 pathogens. While this is a small fraction of the estimated 2.4 million cases of foodborne illness per year it still illustrates the potential severity of these illnesses demonstrating the importance in continuing efforts to reduce these infections.

Keywords: infectious disease, CampylobacterSalmonella

Summary box

What is already known about this subject?

  • Foodborne disease is a common illness in the UK.

  • Previous research has estimated that there are 566 000 cases, 74 000 general practitioner presentations and 7600 hospital admissions related to foodborne disease from 13 known pathogens in UK; no estimate was made for deaths.

  • Campylobacter and norovirus are the most common foodborne pathogens in the UK.

  • Other common foodborne pathogens include Clostridium perfringens and Salmonella.

What are the new findings?

  • This study provides updated estimates of deaths for each of the 11 key foodborne pathogens considered; in total, these 11 pathogens cause 180 deaths per year in the UK (95% credible interval (CrI) 113 to 359).

  • Among them, Campylobacter, C. perfringens, Listeria monocytogenes, Salmonella and norovirus pathogens are responsible for over 98% of these deaths.

  • Ranking between these five is difficult due to overlapping CrIs.

How might it impact on clinical practice in the foreseeable future?

  • This highlights the potential severity of Salmonella, L. monocytogenesC. perfringensCampylobacter and norovirus, particularly in comparison with other infectious intestinal diseases that have a food source.

Research – Is Fresh Produce in Tigray, Ethiopia a Potential Transmission Vehicle for Cryptosporidium and Giardia?


CDC Giardia2

In rural Ethiopia, where people often share their homes with their livestock, infections of humans and animals with Cryptosporidium and Giardia are relatively common. One possible transmission route is consumption of contaminated fresh produce; this study investigated the occurrence of Cryptosporidium and Giardia in fresh produce in four districts of rural Tigray in Ethiopia. Fresh produce samples (n = 55) were analysed using standard laboratory procedures. Overall, 15% (8/55) of samples were found to be contaminated. Although contamination levels were mostly low, a few samples had high numbers of Giardia cysts (up to around 70 cysts per 30 g sample). Molecular analyses were largely unsuccessful, but Giardia Assemblage A was identified in one sample. Contamination with these parasites was identified in two of the four districts, but, although a similar pattern has already been described for water contamination, this may be at least partially explained by sampling bias. Nevertheless, we speculate that access to clean water sources may be an important factor for reducing the occurrence of these pathogens. Given the public health and veterinary burden associated with both parasites, the factors which are of importance for their circulation in the communities and environments deserve further investigation. View Full-Text

Research – Giardiasis Outbreaks — United States, 2012–2017


CDC Giardia2


What is already known about this topic?

Giardiasis is a diarrheal disease caused by the parasite Giardia duodenalis, the most common cause of intestinal parasite infections in the United States.

What is added by this report?

During 2012–2017, public health officials from 26 states reported 111 giardiasis outbreaks involving 760 cases. Leading causes of outbreaks were waterborne and person-to-person exposures. Private residences and child care facilities were the most common settings of giardiasis outbreaks across all transmission modes.

What are the implications for public health practice?

To prevent and control giardiasis outbreaks, CDC recommends prompt diagnosis, maintaining good hand hygiene, cleaning and disinfecting home environments and child care facilities, and monitoring water quality in private well

Giardiasis is a diarrheal disease caused by the parasite Giardia duodenalis, the most common cause of intestinal parasite infections in the United States. Transmission occurs when Giardia cysts spread from feces to water, food, surfaces, or skin and are then ingested. Illness is characterized by gastrointestinal symptoms, including diarrhea, abdominal cramps, greasy stools, bloating or gas, nausea, vomiting, weight loss, and dehydration. Approximately 50% of infections are asymptomatic (1,2). Most symptomatic Giardia infections are self-limited in duration; however, some persons might experience a reoccurrence of symptoms or develop long-term complications (3). During 2012–2017, public health officials from 26 states reported 111 giardiasis outbreaks (760 cases) to the National Outbreak Reporting System (NORS). Three main modes of transmission for these outbreaks were identified: water exposure in 29 (26%) outbreaks, person-to-person contact in 28 (25%) outbreaks, and contaminated food in six (5%) outbreaks. A single transmission mode could not be determined in 48 (43%) of the outbreaks. Private residences and child care facilities were the most common settings of outbreaks for all the transmission modes combined. To prevent and control giardiasis outbreaks, CDC recommends prompt diagnosis, maintaining good hand hygiene, cleaning and disinfecting home environments and child care facilities, and monitoring water quality in private wells.

A giardiasis outbreak is defined as the occurrence of two or more cases of illness epidemiologically linked to a common exposure (1). Health department officials from across the United States (state, local, and District of Columbia), U.S. territories,* and freely associated states voluntarily report outbreaks to NORS. This study included giardiasis outbreak reports submitted to NORS by December 30, 2019 and data reported during 2012–2017 (the year of the earliest case illness onset date through the most recent year for which data were available). NORS data summarized in this study include primary case counts, hospitalizations, and deaths; transmission mode; exposures and settings; and earliest onset date. Negative binomial regression analysis was conducted to assess for annual trends in outbreak counts using SAS (version 9.4; SAS Institute). This activity was reviewed by CDC and conducted consistent with applicable federal law and CDC policy.§

During 2012–2017, public health officials from 26 states reported 111 giardiasis outbreaks with 760 primary cases, 28 hospitalizations, 48 emergency department visits, and no deaths. Among the 703 cases with available data, 370 (53%) persons were male and 333 (47%) persons were female. Pennsylvania reported the largest number of outbreaks with 44 (40%), followed by Minnesota with 11 (10%); no other state reported >10 outbreaks (Figure 1). There was no significant trend in giardiasis outbreaks by year (χ2 = 0.67, p = 0.98) (Figure 2).

Among 29 (26%) waterborne outbreaks (370 cases), exposure sources included tap water systems (e.g., municipal systems or private wells) in nine outbreaks, outdoor freshwater consumption in seven outbreaks, treated recreational water in five outbreaks, untreated recreational water in four outbreaks, and “other” in four outbreaks (Table). Reported settings for waterborne outbreaks included 12 (41%) outdoor areas (e.g., parks and forests) five (17%) private residences, four (14%) camps or cabins, three (10%) community/municipality settings, three (10%) unknown, and two (7%) other settings. Person-to-person transmission was the primary mode identified in 28 (25%) outbreaks, resulting in 129 cases. The primary exposure settings for these outbreaks were 14 (50%) private residences and 12 (43%) child care facilities (Table). Among the 14 settings in private homes, nine (64%) were in households with children aged ≤5 years; two (14%) were in homes with only adults. Among the six (5%) foodborne outbreaks, all foods associated with the five known food exposures were eaten raw or with minimal or no processing. No outbreaks were attributed to animal contact or environmental contamination other than food and water (i.e., contact with objects or surfaces with Giardia). Among all 111 outbreaks, 48 (43%) had an indeterminate or unknown transmission mode, meaning that there was insufficient evidence to implicate one specific primary mode of transmission; 33 (69%) of these outbreaks occurred in private residences (Table).

Research – Potential Risk of Three Zoonotic Protozoa (Cryptosporidium spp., Giardia duodenalis, and Toxoplasma gondii) Transmission from Fish Consumption


In recent decades, worldwide fish consumption has increased notably worldwide. Despite the health benefits of fish consumption, it also can suppose a risk because of fishborne diseases, including parasitic infections. Global changes are leading to the emergence of parasites in new locations and to the appearance of new sources of transmission. That is the case of the zoonotic protozoa Cryptosporidium spp., Giardia duodenalis, and Toxoplasma gondii; all of them reach aquatic environments and have been found in shellfish. Similarly, these protozoa can be present in other aquatic animals, such as fish. The present review gives an overview on these three zoonotic protozoa in order to understand their potential presence in fish and to comprehensively revise all the evidences of fish as a new potential source of Cryptosporidium spp., Giardia duodenalis, and Toxoplasma gondii transmission. All of them have been found in both marine and freshwater fishes. Until now, it has not been possible to demonstrate that fish are natural hosts for these protozoa; otherwise, they would merely act as mechanical transporters. Nevertheless, even if fish only accumulate and transport these protozoa, they could be a “new” source of infection for people. View Full-Text

USA – 32 Union College students sickened by diarrheal illness – Giardia

Houston Chronicle


At least 32 students at an upstate New York college have been diagnosed with a diarrheal illness commonly linked to contaminated lakes, streams and wells.

The Union College students tested positive for giardiasis, while other students showed symptoms of the intestinal disease, Fran’Cee Brown-McClure, the college’s vice president for student affairs and dean of students, wrote in an email to students Friday. Students who live both on campus and off campus became ill.

The Schenectady school reported the first cases of the illness on Oct. 14. School officials said they are working with the local health department to try to determine the source of the disease, which is caused by the giardia parasite.

Research – Research shows estimated 180 deaths per year in UK because of foodborne illness

Food Safety News

Researchers have estimated there are 180 deaths per year in the United Kingdom caused by foodborne diseases from 11 pathogens.

The Food Standards Agency (FSA) estimates that about 2.4 million cases of foodborne illness occur every year in the UK.

Foodborne norovirus is projected to cause 56 deaths per year, Salmonella 33 deaths, Listeria monocytogenes 26, Clostridium perfringens 25, and Campylobacter 21. Most fatalities occur in those aged 75 years and older.

Foodborne deaths from Shigella, Cryptosporidium, Giardia, adenovirus, astrovirus and rotavirus are rare, according to the study published in the journal BMJ Open Gastroenterology.