Beaver fever, er, giardiasis in the US

That’s what we call it in Ontario. Beaver poop in water consumed by thirsty hikers

Great source of Giardi. The Centers for Disease Control writes:

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.

Reported giardiasis outbreaks (N = 111), by mode of transmission* and year of earliest illness onset date — United States, 2012–2017

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 wells.

Giardiasis Outbreaks—United States, 2012-2017

Morbidity and Mortality Weekly Report

Erin E. Conners, PhD1,2; Allison D. Miller, MPH1; Neha Balachandran, MPH3; Brittany M. Robinson, MPH1; Katharine M. Benedict, DVM, PhD1

As parasites might in your blood

Human Parasitic Diseases: A Diagnostic Atlas is a comprehensive and invaluable resource for parasitologists, microbiologists, pathologists, and infectious disease practitioners. Lawrence R. Ash, PhD, and Thomas C. Orihel, PhD, have curated a beautiful photographic series of common and rare parasites shown in tissue, blood, feces, and free-living forms. Organized by phylum, genera, and species, this book provides detailed yet practical assistance in identifying and diagnosing human parasitic diseases. Each section starts with a brief overview of the epidemiology, life cycle, transmission, and clinical manifestations of the parasite, detailed enough to orient the reader to the clinical relevance of the pathogen without distracting from its macroscopic and microscopic diagnostic features. The authors provide up-to-date references of each parasite’s clinical manifestations and diagnostic procedures.

In addition to the beautiful, high-quality photomicrographs, the authors supplement the book with detailed diagrams clarifying the key microscopic diagnostic features. These details enable the reader to differentiate between closely related parasites.

This book offers many unique aspects. First, the authors provide multiple images comparing subtle differences in the appearance of the same parasite, which will reassure anyone who has struggled to identify a blood smear of a parasite that does not quite fit the textbook example. These images emphasize the subtlety of microscopic identification and pattern recognition. Second, this atlas emphasizes the appearance of parasites in histologic findings and tissue. The authors acknowledge the difficulty of making a histologic diagnosis on the basis of fragments of larger parasites or those that have degenerated in tissues. Third, the book contains a 1911 Arthur Looss quote emphasizing the interconnectedness of animal and human parasites and highlighting the need to consider animal pathogens that have rarely infected humans. This perspective is relevant in a world with increasingly immunosuppressed patients and unprecedented levels of travel and global trade. Therefore, this book is a compelling reference volume for pathologists and microbiology or clinical infectious disease training programs.

Particularly useful for today’s clinical infectious diseases practitioners is the last section of the book, which covers artifacts for which macroscopic or microscopic appearance could be easily confused even by an experienced pathologist. This section is a helpful reminder of the diagnostic challenges facing clinicians seeing patients who believe they have an infestation but in whom no parasite can be found.

I will certainly use this atlas as a reference and training guide and will most likely browse through its pages before recertification examinations. Any reader with an inclination towards parasitology will appreciate the authors and their colleagues’ fascinating careers in this field.

Human Parasitic Diseases: A diagnostic atlas, August 2020

Emerging Infectious Diseases vol. 26 no. 8

Lawrence Ash & Thomas Orihel

It’s not a war: FDA arming itself with science to help prevent Cyclospora infections

Steven Musser Ph.D., Deputy Director for Scientific Operations, FDA’s Center for Food Safety and Applied Nutrition (CFSAN) and Alexandre da Silva, Ph.D., Lead Parasitologist at CFSAN’s Office of Applied Research and Safety Assessment, write that Cyclospora cayetanensis is so small that it can only be seen with a microscope. However, there is nothing small about the U.S. Food and Drug Administration’s work to help protect consumers from the foodborne illness that this parasite can cause.

Of course it’s small. So are the trillion of microorganisms inside each of us.

Cyclospora has been on the public radar since at least 1996.

Cyclosporiasis is an intestinal illness caused by consumption of foods, mainly fresh produce, that are contaminated with Cyclospora. The FDA has been working to help prevent contaminated product from reaching consumers, gathering the scientific knowledge that will help to better detect the parasite in food and the environment, and gathering data to better understand how food is contaminated by the parasite and help prevent contamination in the future. We’re also sharing what we know with stakeholders in the public and private sectors.

Because several past outbreaks have been associated with fresh herbs, the FDA has been conducting surveillance sampling of fresh cilantro, parsley and basil. A quarterly update on this food surveillance study was released today. As this effort continues, our goal is to collect enough samples to provide a precise estimate of the prevalence of contamination of Cyclospora in our food supply, enabling us to better understand our vulnerability to Cyclospora contamination.     

The FDA is also acting on what we already know about where Cyclospora is found and how contamination can be prevented.   

In 2019, 10% of the Cyclospora infections reported between May and August were linked to a multi-state outbreak associated with fresh imported basil that started in mid-June and was declared over in October. FDA increased its screening at the border of basil exported by the company tied to the outbreak before the company voluntarily recalled its product and ceased shipping while corrective measures were implemented.

The FDA is also tracking contamination in domestically-grown produce. The first confirmed evidence of Cyclospora in domestically grown produce was detected in 2018 in cilantro, a finding not associated with an outbreak of illnesses. As with bacterial pathogens, if the parasite is found on produce, the FDA follows up with inspections and sampling, working with the business to take the actions needed to protect public health.

The FDA has been reaching out to farmers to increase awareness of Cyclospora and actions that can be taken on the farm to reduce the likelihood of contamination. For example, ways to control sources of contamination include proper use, maintenance and cleaning of toilet and handwashing facilities. We created education and outreach materials for farmers, including the Cyclosporiasis and Fresh Produce Fact Sheet

In late 2014, the FDA’s Center for Food Safety and Applied Nutrition established a Foodborne Parasitology Research Program, and in collaboration with the CDC, has been sequencing the genomes of several different strains of C. cayetanensis, enabling the development of genetic typing methods. In 2016, we created a genome database named “CycloTrakr” to be used as a public repository of genomic data at the National Center for Biotechnology Information (NCBI). This is an important first step towards the goal of linking, in real-time, the genetic fingerprints of Cyclospora in contaminated food and sick people to pinpoint the source of the outbreaks.

The agency has also pioneered ways to detect the parasite, developing and validating new methods to test for Cyclospora in produce and water. The first of these new methods was used for the first time in 2018 to confirm the presence of the parasite in a salad mix product tied to an outbreak that sickened hundreds of people. 

In July 2019, the FDA made its second major advance in Cyclospora detection, completing studies that resulted in a novel, validated method to test agricultural water for the presence of the parasite. Water used on farms is a potential source of the contaminants that cause foodborne illnesses. Analysts from FDA laboratories are being trained in the use of this method for regulatory testing. 

Cyclospora contaminated food in the US, health alert issued

Cyclospora is one of those pathogens spread through poop and water/food tends to be the most favorable vehicle of transmission.

The Federal Safety and Inspection Service has issued a health alert over certain meat products over concern for Cyclospora.
The agency is telling people to be extra cautious with beef pork and poultry salad and wrap products out of Caito Foods LLC, in Indianapolis, Indiana.
The items with “best by” or “sell by” dates ranging from July 18th to July 23rd are under the alert. 
The problem within Caito Foods is related to the lettuce supplier, Fresh Express. The chopped romaine is being recalled.
Cyclospora infection, defined by the Centers for Disease Control, is an intestinal illness caused by a parasite. The infection can cause Cyclosporiasis.
The symptoms of Cyclosporiasis include loss of appetite, weight loss, cramping, bloating, nausea, fatigue, and other flu-like symptoms.

Scientists discover how Giardia makes people ill

One of my favorite pastimes is to go camping with the family and enjoy nature….in a cabin. I’m getting too old to tent and contend with the mosquitoes and bears. One thing is for sure, I avoid drinking water that hasn’t been treated due to the potential risk of parasites, in particular, Giardia.

BBC News reports

Now scientists say they have discovered how the parasites that cause giardiasis – one of the world’s most common gastric diseases – make people ill.
Giardia parasites mimic human cell functions to break apart cells in the gut and feed inside, researchers found.
This also allows bacteria already present in the body to join in and feed from the same nutrients, they said.
‘Ready meals’
Some 500,000 cases of giardiasis are diagnosed each year, with people typically picking up the disease by drinking infected water or contaminated food.
Symptoms include severe diarrhoea, stomach pains, bloating, flatulence and fatigue and can last weeks or months without treatment.
Although it is found throughout the world, it is most prevalent in developing countries and is one of the most common gastric diseases caught by backpackers.
But although scientists have known of giardia’s existence for hundreds of years, until now it remained unclear how it makes people sick.
Giardia parasites are picked up in infected water or contaminated food, usually in developing countries. 
Researchers found the giardia parasite produces two types of protein that enable it to cut through layers of protective mucus in the gut – breaking the links that knit cells together – in order to easily access the nutrients within them.
One of the proteins does this by mimicking a group of human proteins called tenascins, which regulate cell adhesion and break apart when necessary, such as during wound healing.
But the giardia tenascins are used instead to upset the body’s balance by preventing healing of the junctions between cells that hold them together.
One of the study’s authors, Dr Kevin Tyler, from UEA’s Norwich medical school, said: “Because the giardia have broken down the cell barriers and made all these nutrients available, other, opportunistic bacteria can move in to take advantage of these ‘ready meals’ which can make giardiasis even more severe for some.”
‘Bad bacteria’
Those suffering from giardiasis are usually able to recover from the illness with or without antibiotics.
However, about half of those who get the parasite experience no symptoms of the illness.
Dr Tyler said the difference in the severity of disease might be explained by the proportion of “good” and “bad” bacteria in the gut.
Those who become more ill may have a higher proportion of “bad bacteria” feeding off nutrients released by the giardia parasite, Dr Tyler said.
Dr Tyler told the BBC: “Some people have a gut that is predominantly full of quite good bacteria that doesn’t cause inflammation and illness and indeed may protect from it.
“What we think is that in people who have the bad bacteria, the pro-inflammatory bacteria, those start to use the nutrients that have been unleashed by the giardia.
“The giardia does the damage, allowing the nutrients to flow into the gut, and then if you have the wrong kind of bacteria you get this cycle of inflammation.”
This is why probiotic drinks and supplements – which populate the gut with good bacteria – are helpful in treating giardiasis, he said.
The study was published in the journal GigaScience.
How to avoid giardiasis
When abroad make sure to drink filtered or bottled water
Practice good hygiene
Avoid eating food that may be contaminated
Avoid water (drinking or recreational) that may be contaminated
Clean up after ill people and pets


We’re all hosts on a parasitic planet: Crypto edition

This is cool: the parasite seems to deliver RNA transcripts into infected hosts cells, which may then take over parts of transcription in the host.

crypto-mouse-epi-cellCryptosporidium parvum is an important opportunistic parasite pathogen for immunocompromised individuals and a common cause of diarrhea in young children. Previous studies have identified a panel of RNA transcripts of very low protein-coding potential in C. parvum.

Using an in vitro model of human intestinal cryptosporidiosis, we report here that some of these C. parvum RNA transcripts were selectively delivered into the nuclei of host epithelial cells during C. parvum infection. Nuclear delivery of several such parasitic RNAs, including Cdg7_FLc_0990, involved heat-shock protein 70-mediated nuclear importing mechanism. Overexpression of Cdg7_FLc_0990 in intestinal epithelial cells resulted in significant changes in expression levels of specific genes, with significant overlapping with alterations in gene expression profile detected in host cells following C. parvum infection.

Our data demonstrate that C. parvum transcripts of low protein-coding potential are selectively delivered into epithelial cells during infection and may modulate gene transcription in infected host cells.

Delivery of parasite RNA transcripts into infected epithelial cells during Cryptosporidium infection and its potential impact on host gene transcription

J Infect Dis. (2016) doi: 10.1093/infdis/jiw607

Yang Wang, Ai-Yu Gong, Shibin Ma, Xiqiang Chen, Yan Li, Chun-Jen Su, Dana Norall, Jing Chen, Juliane K. Strauss-Soukup, Xian-Ming Chen

Our parasites and vermin reveal secrets of human history

My ex used to pop these things out of one particular spot on my face.

demodex_wide-3ae0bab529fbd9dbd3b98ff591fdd0542a271c65-s1600-c85Rae Ellen Bichell  of NPR reports they look like tiny tubes with stumpy legs. They can nestle snugly into pores, right at the base of small hairs. And there are probably hundreds on your face.

We’re taking about Demodex folliculorum, the mite that calls your hair follicles home. “Probably if you’ve ever gotten a gross gunky plug out of a nose pore, that’s what it looks like,” says Michelle Trautwein, an evolutionary biologist at the California Academy of Sciences. “When you get to know them, they’re actually pretty adorable.”

Trautwein and her colleagues have peeled the mites off microscope slides that they super-glued to their faces. They’ve scraped the little guys off people’s foreheads with the curved end of a bobby pin. They’ve even ferreted out the insects’ DNA from tiny spatulas of face grease.” They’ve probably been with us since the origin of our species,” she says.

And Trautwein thinks the mites could help answer questions about human migrations through history, perhaps more than genetics

Top 10 list of foodborne parasites released

A Top 10 list identifying the foodborne parasites of greatest global concern has been released today, and new guidelines are being developed to control them.

parasiteThe parasites affect the health of millions of people every year, infecting muscle tissues and organs, causing epilepsy, anaphylactic shock, amoebic dysentery and other problems. Some can live on in our bodies for decades.

Despite their huge social costs and global impacts, information is generally lacking regarding just where these parasites come from, how they live in the human body, and – most importantly – how they make us sick.

As a first step in tackling the problem, the UN’s Food and Agriculture Organization (FAO) and World Health Organization (WHO) are initially focusing on the ten food borne parasites with the greatest global impact. The rankings contained in today’s FAO-WHO report, Multicriteria-based ranking for risk management of food-borne parasites, are based on the parasites’ burden on human health and other factors, and includes information on where they can be found.

The top ten are:

Taenia solium (pork tapeworm): In pork

Echinococcus granulosus (hydatid worm or dog tapeworm): In fresh produce

Echinococcus multilocularis (a type of tapeworm): In fresh produce

Toxoplasma gondii (protozoa): In meat from small ruminants, pork, beef, game meat (red meat and organs)

Cryptosporidium spp.(protozoa): In fresh produce, fruit juice, milk

Entamoeba histolytica (protozoa): In fresh produce

Trichinella spiralis (pork worm): In pork

Opisthorchiidae (family of flatworms): In freshwater fish

Ascaris spp. (small intestinal roundworms): In fresh produce

Trypanosoma cruzi (protozoa): In fruit juices

small_reportcover.gifThe list and supporting report were developed following a request by the global food standards body, the Codex Alimentarius Commission (Codex), for FAO and WHO to review the current status of knowledge on parasites in food and their public health and trade impacts.

The Codex Committee on Food Hygiene is now developing new guidelines for the control of these parasites. FAO and WHO are supporting the process by providing scientific and technical information.

The aim is to develop new standards for the global food trade that will help countries control the presence of these parasites in the food chain.

Australian man gravely ill after eating slugs ‘for a dare’

An Australian man is gravely ill in hospital after eating two slugs as part of a dare.

Doctors believe that the 21-year-old, who has not been named, contracted the rare rat lungworm parasite from the slugs.

The disease, which is a type of meningitis, can lead to swelling of the brain and spinal cord and has been known to be fatal.

The rat lungworm parasite, also known as Angiostrongylus cantonensis, is passed to slugs from rodent droppings. It can also be caught from raw vegetables or fruit which have not been washed properly.

Doctors said the man told them he had swallowed two slugs from a Sydney garden after a dare, and had then fallen ill.


Keep poop off produce; parasites on cucumbers, first reported foodborne outbreak associated with microsporidia, Sweden, October 2009

Swedish researchers have tracked a human outbreak of the parasite, microsporidia, to raw cucumbers, and propose the most likely source was human manure during growing.

From the paper:
Our investigations suggest that cucumber slices in both cheese sandwiches and a salad were the most probable vehicle of transmission. Since no leftover food samples were available for testing and because little is known about E. bieneusi in the context of foodborne outbreaks, it is difficult to conclusively
implicate this organism as the agent responsible for the outbreak. However, the finding that all six samples available for genotyping were genetically indistinguishable (genotype C) together with the fact that, despite extensive testing, no other organisms were identified in the stool samples strongly suggest that E. bieneusi was the causative agent. Furthermore, the finding that all 19 stool samples from persons belonging to the same professional group who had not attended the event were negative for microsporidia provides additional evidence that the detection of E. bieneusi was not a chance finding. Although these samples were taken 7 months after the event, they nevertheless provide an indication of the prevalence of microsporidia in a population with similar demographic characteristics.

We cannot state with certainty how and where the sliced cucumbers were contaminated. Contamination during final preparation at the hotel seems unlikely because the cucumbers were not processed any further but were added directly to the sandwiches. Furthermore, a high contamination dose is suspected (due to high attack rate in a healthy population) which is unlikely to have occurred because preparation of the sandwiches was carried out by an asymptomatic food handler. The sealed bags of cucumber slices had been
refrigerated before use so it is improbable that contamination took place during storage. Similarly, contamination during initial processing at the wholesale supplier, although possible, seems unlikely based on the description of the procedures used. The most likely hypothesis of contamination is that it occurred before harvest, either by contaminated manure, manure compost, sewage sludge, irrigation water, runoff water from livestock operations or directly from wild and domestic animals. These potential contamination events are all plausible and consistent with the assumption that the level of contamination must have been high. Unfortunately, because we were unable to trace the cucumbers back to the farm where they were grown, we could not investigate these
possible contamination routes further. However, additional information is provided by the genotyping results. While there have been several cases of genotype C identified in humans, predominantly in HIV-negative organ transplant recipients in Europe [25, 26], there is only one report on animals in the
literature [27]. Thus, while a zoonotic link cannot be ruled out, the involvement of this genotype suggests that the source of contamination in this outbreak was
of human (fecal) origin.

While thorough washing of fresh produce remains of utmost importance in preventing foodborne illness and should continue to be emphasized, sometimes washing may be insufficient to remove all pathogens.

In this instance, it may have been that the level of contamination was so high that washing was unable to remove enough of the microbial load so as to prevent infection. Alternatively, it may be that microsporidian spores are capable of strong adhesion to, or internalization in, certain types of produce, thereby
successfully evading the effects of washing and disinfection.

A recent paper by researchers in the USA demonstrated that Cryptosporidium oocysts were capable of strongly adhering to spinach plants after contact with contaminated water and were also internalized within the leaves, thus making
entirely ineffective [28].
First reported foodborne outbreak associated with microsporidia, SWEDEN, October 2009
Epidemiology and Infection
V. Decraene, M. Lebbad, S. Botero-Kleiven, A.-M. Gustavsson and M. Löfdahl
Microsporidia are spore-forming intracellular parasites that infrequently cause disease in immunocompetent persons. This study describes the first report of a foodborne microsporidiosis outbreak which affected persons visiting a hotel in Sweden. Enterocytozoon bieneusi was identified in stool samples from 7/11 case-patients, all six sequenced samples were genotype C. To confirm that this was not a chance finding, 19 stool samples submitted by healthy persons from a comparable group who did not visit the hotel on that day were tested; all were negative for microsporidia. A retrospective cohort study identified 135 case-patients (attack rate 30%). The median incubation period was 9 days. Consumption of cheese sandwiches [relative risk (RR) 4·1, 95% confidence interval (CI) 1·4–12·2] and salad (RR 2·1, 95% CI 1·1–4) were associated with illness. Both items contained pre-washed, ready-to-eat cucumber slices. Microsporidia may be an under-reported cause of gastrointestinal outbreaks; we recommend that microsporidia be explored as potential causative agents in food- and waterborne outbreaks, especially when no other organisms are identified.