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.