Stefan writes:

Dear TWIP-Team,

Greetings from Heidelberg again, cloudy 17°C today, which necessitated wearing a long-sleeve shirt again…

To the case, I believe, the findings of giardia and coccidia are surrogates/proxies only to the little girl’s exposure to dogs and possibly dog feces. A frequently encountered helminth parasite is Toxocara canis, the dog roundworm, for which humans are dead-end hosts.

Apart from ocular larva migrans (would need to check this girl) visceral larva migrans is a possible symptom complex which resembles larvae migrating through various parts of the body. Possibly symptoms are abdominal pain, stool irregularities, wheezing and in rarer cases also central nervous system symptoms (CNS invasion). Indirect effects, are allergic phenomena like rashes or in this case facial swelling. For antiparasitic therapy there is little evidence, but in view of possible consequences, albendazole is strongly recommended, in addition to supportive care (inhalative steroids in this case and systemic steroids may be considered in some cases).

Hoping my guess is correct and I am lucky enough to win a book 🙂

Best regards


PS: disclosure: no ChatGPT used 😉

Joshua writes:
Dear TWiPpers,

As the patient described at the end of Episode 218 seems to be of the canine variety, I thought to consult my two labradoodles, Harold and Eliza, about the symptoms, likely diagnosis and potential treatment of this case.

Based on their characteristic behaviours, however, Harold would be puzzled, whilst Eliza would bark loudly, wag her tail, and tilt her head from side to side, before giving me a knowing glance, without telling me what she thinks. Though dogs are man’s best friend, and like to be patted, unless they have been trained to sniff out a specific pathogen, they are not able to give veterinary advice.

I decided not to consult Annabel the cat either, as her opinions of dogs are very poor, and she keeps her secret knowledge of the world to herself.

Canine coccidia and giardia are generally subclinical infections in dogs, and would not produce the facial swelling and respiratory effort described. If a fungal infection is possible, I would suggest Aspergillus fumigatus, or another soilborne species, which can cause those symptoms.

According to a 2012 paper available online, entitled “A review of the pathology and treatment of canine respiratory infections”, by Vieson, Piñeyro and LeRoith, such fungal rhinitis can present with an array of distressing symptoms, including “mucopurulent discharge…, sneezing, epistaxis,… nasal depigmentation or ulceration. Stertor and stridor… and… facial deformity… with or without lacrimal duct obstruction and epiphora.” Epitaxis means a nosebleed; stertor and stridor, noisy breathing; and epiphora, watery eyes – so why not say so? Treatment would best make use of topical antifungal treatments instilled into the nasal cavity.

However, if a fungal infection is not within the remit of TWiP, then it could be a case of nasal infection by an aquatic protistan parasite, Rhinosporidium seeberi, though sporadic cases thereof have only been reported from the southern U.S., no further north than Missouri, which is a long way from Central Park, I believe; and facial swelling is not reported as a symptom of this protist. Infection with this parasite produces a nasal polyp – treatment is excision thereof.

Many thanks as always for your wonderful work!


Joshua, on behalf of Harold, Eliza, and Annabel.

Shan writes:

Dear Dogter Griffin & pack,

Thank you for this most difficult and challenging case regarding the 19 month old female patient with respiratory issues, loose stools, and facial swelling.

This poor patient sounds sick as a dog. What could be going on here? Allow me to relay my pet theory:

Given that testing has revealed canine coccidia and giardia, I suspect this patient has… canine coccidia and giardia. However, these parasitic infections explain the loose stools, but not the facial swelling and increased respiratory effort. I suspect this poor girl is battling multiple afflictions.

As we know, Occam was not a doctor of veterinary medicine and this patient can have as many diseases as she darn well pleases.

Sounds like an allergic reaction in addition to the parasites. Did this 19 month old get into the kitchen trash and eat something she shouldn’t have? Was she bitten by a tick? A spider?

Relistening to the case and looking for clues, I noted the following: 

Firstly, the mere mention of Paul Calle inflamed my latent trust issues from TWiP #109 in which Paul led us down the garden path regarding the species of the afflicted patient. Hmm.

Secondly, I noted Dr. Griffin’s unusual pronunciation of “Jeff BEEEzos”. Initially, I chalked this up to Dr. Griffin being an NYU grad (“sontimeter” and all) but it was the shout out to Chevy Chase that got my gears turning. I eschewed recent trends and consulted YouTube instead of ChatGPT. A search for “Chevy Chase” and “bees” furnished me with Chevy’s famous “Killer Bees” Saturday Night Live skit and I knew this case was closed. 

Our patient is a dog, with multiple parasitic infections, and a bee sting to the snout.

My treatment plan is as follows:

1) Reassure the patient that she is a GOOD GIRL

2) Sulfadimethoxine for the coccidia

3) Fenbendazole for the giardia

4) Diphenhydramine for the bee sting

5) 1 cup kibble B.I.D.

With regard to the 22 year old daughter who has had a lot of contact with the patient:

The chances of parasitic infection are low, but possible, and Dr. Griffin’s daughter is likely fine, provided she can run really fast from bees.

I expect at this point the patient has embarked on her road to recovery and has gained a new leash on life.

Sorry for the torrent of obvious dog jokes you are no doubt receiving from every submission this month, but you brought this upon yourself. 😉

Please give your poor pooch a scratch behind the ears for me. Hope she’s doing well.

All the best from sunny Snohomish, Washington,


Giovanni writes:

TWiP 218 Case Study

Hi TWiP team, I don’t have much biology experience, took some classes in college but swiftly changed my major to Economics as I struggled with the memorization aspect.  However, I’ve still maintained my love for science and I’m very excited to tackle this case.

This being a 19-month-old (dog) dealing with labored breathing and swelling of the face, loose stool, and feces tested positive for K9 coccidia & giardia your little pup must have consumed the feces of another dog infected with the parasites.  Also, as facial swelling may be caused by an allergic reaction, it could be that the little one somehow got access to contaminated food they were not supposed to be eating.  However, as both K9 coccidia & giardia cause diarrhea, K9 coccidia symptoms include dehydration and lethargy, this could be what’s causing the labored breathing, while the facial swelling might be a sign of an allergic reaction.

Finally, as most forms of coccidia in dogs don’t transmit to humans, and giardia transmission also has a low probability, your 22-year-old could be fine.  That said, there is a species of coccidia called Cryptosporidium which can infect humans, and this is a particularly worrisome parasite.  The dog should begin treatment right away, and it could be helpful that your daughter gets checked to ensure no sneaky parasite made the jump.


Thank for all that you do, I listen to almost all of your shows, and because of an episode of TWiV I was motivated to learn more about the immune system by picking up How the Immune System Works by Lauren Sompayrac.



Paul writes:

Chat-GPT NOT used! Literature research takes a few minutes to figure out the main points of the solution.

This is the story of Dr. Griffin’s daughter’s 19-month old dog who is infected with canine coccidia and giardia.

She will not become infected with canine coccidia as it does not infect humans. The risk for her being infected with giardia depends on the genotype. Giardia has 8 genotypes, termed assemblages. Assemblages A & B can infect both dogs and humans.  Assemblages C & D, common in dogs, do not infect humans.

The symptoms of respiratory effort and facial swelling are due to undernutrition, anemia and low albumin caused by the infection.  Coccidia and giardia in dogs may be asymptomatic or cause similar symptoms, so it is not possible to be sure which organism, or if both, are causing the illness.

Treatment: both organisms are susceptible to metronidazole, so that would be the first option.

Paul Blanchard, MD

Michelle and Alexander from the First Vienna Parasitology Passion Club write:<=winner

Dear Dog-Casters,

We were unable to find a unifying diagnosis for this canine patient. We can only hypothesize that she is suffering from an infection with several parasites, which we will list below. Regarding the question of infectivity for adult humans, we came up with some more relevant information.

Three symptoms were described in the case:

Increased work of breathing: This symptom was noticed before the onset of diarrhea or facial swelling. Lungs are clear to auscultation. Therefore, cardiac pathology or anemia seem the most likely causes.

Diarrhea: There are many causes of loose stools, but the organisms isolated would explain this symptom.

Facial swelling: From the description given, it is unclear whether this is localized swelling as a result of one or several masses or if it is edema; Likely causes of facial edema include allergy, cardiac or vascular obstruction.

Assuming that the diarrhea is caused by the protozoa in the stool, an infection with dirofilaria immitis could explain increased work of breathing and congestion of the superior vena cava (if indeed dogs have one of those). This worm is transmitted via mosquito bite and is commonly found in the eastern US. 

An unlikely differential is echinococcosis; while dogs usually harbor the adult tapeworm within their GI tract, they can rarely present with cystic echinococcosis. Pulmonary lesions could explain respiratory distress and a burst cyst could lead to an anaphylactic reaction with facial swelling and diarrhea. 

While dirofilaria spp. only cause rare cases of aberrant infection in humans, some coccidia and giardia species can be transmitted to humans and can cause symptomatic infection. It is therefore important to practice good hygiene when dealing with your dog’s excretions. Other parasites to watch out for include several intestinal protozoa, necator, ancylostoma, trichuris, taenia and toxocara.

Thank you for this great case. All the best,

Michelle and Alexander from the First Vienna Parasitology Passion Club

PS: If it’s possible, we would like to submit a case to the podcast. It concerns a common illness we often encounter in clinic that has not been discussed on TWiP as of yet. 

Kimona writes:

Dear TWiP Team!

I think our patient is a dog, or perhaps still a puppy at 19 months? She harbours canine Coccidia and an unknown Giardia subgroup in her stool. Multiple genera and species cause coccidiosis and each tends to be species specific with a few exceptions (like T. gondii in cats). 

References were made to TWiP episode #110 discussing avian malaria infections at the Bronx Zoo. I found very little on canine Plasmodium disease except that it is mainly caused by P. malariae.  Based on Paul Calle’s description in penguins, the resulting vasculitis can affect multi-organ inflammation and cause pulmonary edema in the lungs and subsequent dyspnea, at least in birds. Was the dog visiting the zoo and bitten by a plasmodium infected mosquito?…

Clinical coccidia and giardia in dogs are either asymptomatic or present with mainly diarrheal disease and only puppies and immunocompromised animals are likely to develop severe disease with enteritis. Extreme dehydration and malnourishment might cause an increased respiratory effort and possibly audible panting. The prevalence of giardia in dogs can in some shelters and kennels be as high as 100%. Giardia intestinalis (or duodenalis) is divided into assemblages; A/B are potentially zoonotic with risk of transmission from dog to human; C/D are host-specific to dogs (G. canis) and rarely zoonotic. 

The swollen face has me stumped. Aside from a bee sting or adverse/allergic reaction, other causes would include lymphatic obstruction or primary heart failure. Apparently in dogs heart failure can present with upper body swelling extending to the head and face and might also trigger pulmonary edema, hypoxia, and panting.

So, is there a secondary infection causing heart failure symptoms? Several helminthic infections common to dogs have the potential to do this. Heartworm (Dirofilaria immitus) will eventually infect pulmonary vasculature; hookworm, ancylostoma spp., suck blood in the intestines causing anemia; roundworm, Toxocara canis, can cause recurring diarrhea and pulmonary edema from larval migration through the lungs; likewise for Strongyloides. 

To be clear, I am coming up short with a definitive diagnosis and my best conclusion is that our patient is a shelter pup, perhaps sub-optimally treated with anthelmintics and now dehydrated and malnourished from chronic diarrhea! If the Giardia is assemblage C or D, it is unlikely to be of risk to Daniel’s daughter, whereas assemblage A or B could be, if proper hygiene is not followed. Canine coccidia should not be infectious to humans, as cyclospora cayetanensis is listed as the only coccidian protozoan to cause human disease.

But I cannot imagine that this pup’s clinical condition would have evaded Daniel’s scrutiny prior to deteriorating into florid heart failure! There must be a better explanation that I eagerly await to hear.

In anticipation, Kimona

Gina writes:

I’m stumped because Daniel actually told us both infections! Is it the patient we are guessing? The stool sample was positive for giardia and canine coccidia so that’s my guess, I guess? Is it one of Daniel’s lovable canines??🤷🏻‍♀️⁉️⁉️

You guys are the best. Thank you. 



Martha writes:

Dear TWiPs: 

As is usual I may have delayed too long in responding. I will try to keep this short as I think you will get a lot of responses. 

The case in episode 218  seems to present us with three questions. 

1.What species is the patient? 

2.What is causing the increased respiratory effort, facial swelling and diarrhea? 

3.And is Dr.Griffin’s daughter at risk?

We are given the information that the stool is positive for canine coccidia and giardia (species not specified). We are also told that the case was discussed with Dr.Paul Calle, head vet at the WildLife Conservation Society and we are recommended the TWiP episode with Dr. Calle. That was an excellent episode about avian malaria in penguins.

So to sort this out I have wandered around the internet checking out vet med sites. My guesses are. 

1. Most likely the patient is a dog. The canine coccidia is a good hint. I could imagine Dr. Griffin harboring penguins or other exotic birds from non-malarial regions, but I think it might have come up in prior discussions.

2. Is it malaria? I read that dogs can be infected by Plasmodium malariae which I think is not currently in circulation in the NYC area. The mosquito borne illness they are at more risk for is from Dirofilaria immitis. The symptoms of increased respiratory effort and facial swelling are on the list of disease manifestations. The symptoms of canine coccidia and giardia mostly are diarrhea related. So I’m guessing Dirofilariasis is the main problem. The dog likely has no idea who William of Ockham is, and therefore may have more than one disease.

3. Dirofilaria can infect humans if bitten by a mosquito carrying the parasite, not by contact with the dog. According to google, canine coccidia is not a problem for humans. Giardia from the dog I assume could present with the usual symptoms of giardiasis. But I am sure that Dr.Griffin’s daughter has excellent hand hygiene so is at low risk. 

I hope I am not too late for this episode. Best wishes to you all from soggy eastern Massachusetts.