Randon writes:

Hi,

I’m currently a student at UW taking the 460 parasitology course. Based on the new case presented as daily fevers, low platelet count, and the area that he has been in I would be leaning towards a Plasmodium knowlesi infection. I think that although he doesn’t have hepatosplenomegaly his liver cells and kidney cells are being damaged by the parasite causing elevated serum creatinine and aminotransferases. 

Sincerely,

Randon

Malia writes:

Hello!

My name is Malia, and I am a student at the University of Washington. I am currently taking a medical mycology and parasitology course where students are encouraged to send in guesses to your podcast! This is my first time submitting a guess, but I will still try to answer to the best of my ability. 🙂

One of the symptoms that most stood out to me was the patient exhibiting fevers every day. It reminded me of what I learned about Plasmodium species, and the different periodicity of attacks each species could have. The only species in my notes with a 24hr fever is P. knowlesi (as opposed to tertian or quartan fever). I did some digging and found out that P. knowlesi can be found in Malaysia’s jungle environment, as it can infect certain macaques that interact with orangutans and proboscis monkeys. 

My notes also include symptoms of P. knowlesi, the most notable being:

 – Thrombocytopenia 

 – Severe anemia 

which were some of the symptoms discussed in our patient. 

I know I’m probably missing some other factors, but I’m happy that I’ve at least deduced the information you’ve given and came up with at least one parasite to share with you all! 🙂

Cheers,

Malia Laigo 🙂

Chan writes:

Hi all,

I think our patient from Malaysia has malaria caused by Plasmodium knowlesi. Here is the information that points me towards this parasite: 

  • The patient’s visit to the jungle and close proximity to monkeys is a risk factor for acquiring the parasite. The large majority of symptomatic P. knowlesi infections have been reported in adult males who have spent time in forested regions. Macaque monkeys are the natural host of P. knowlesi, so Anopheles mosquitoes (the vector) can transmit the parasite from the monkeys to humans. Female Anopheles mosquitoes are active late in the evening or at night. Our patient was near the jungle in the evening, which explains how he could have been bit by a female Anopheles mosquito carrying P. knowlesi parasites and acquired the infection.
  • The patient’s family is healthy, which makes sense since they spent more time inside than the patient so were thus less exposed to mosquitos which could infect them with P. knowlesi. 
  • The patient was admitted to the hospital in December. The rainy season in northeastern Malaysia is from November to March. Mosquitoes need water to lay their eggs, so increased rain provides more standing water where they can lay their eggs. This leads to an increase in mosquito populations, which means an increase in P. knowlesi transmission.
  • P. knowlesi is endemic in southeast Asia The greatest number of knowlesi malaria cases are reported from Malaysian states like Sarawak, lining up with the patient’s history (he is from the Sarawak portion of Malaysia).
  • The patient visited the jungle two weeks prior to symptoms, which makes sense since the incubation period for P. knowlesi is 8-12 days.
  • P. knowlesi has a 24-hour life cycle in humans. When the infected red blood cell ruptures, it causes a fever. Thus, patients typically experience daily fever spikes like our patient did.
  • Other than fever, the patient exhibited the following symptoms that line up with knowlesi malaria:
    • Fever (seen in 100% of cases)
    • Chills and headache (89-94%)
    • Nausea (24-34%)
    • Tachycardia
    • Increased respiratory rate (respiratory distress is a common manifestation, increased respiratory rate could be the start of this symptom)
    • No enlargement of liver or spleen (hepatosplenomegaly is not a hallmark feature of knowlesi malaria; hepatomegaly is seen in 24-40% of cases and splenomegaly in 6-33% of cases)
  • Additionally, the following lab results also points towards a P. knowlesi infection:
    • Anemia (due to intravascular and extravascular hemolysis)
    • Thrombocytopenia, which is near universal in adult knowlesi malaria
    • Abnormal coagulation studies
    • Elevated serum creatinine (acute kidney injury is a common manifestation in knowlesi malaria; elevated serum creatinine levels can indicate kidney dysfunction or failure)
    • Elevated serum aminotransferases (mild elevation of liver transaminases is a common manifestation)

However, there is one thing that doesn’t align with a P. knowlesi infection. The patient has a low white blood cell count, which is abnormal because total white blood cell counts are usually normal or elevated in P. knowlesi infections (neutrophilia is seen in severe disease). However, everything else points to a Plasmodium knowlesi infection.

Sources:

Best,

Chan

Charlotte writes:

Dear TWiP Team,

I’m a third-year microbiology student writing for the first time from the very cloudy University of Washington in Seattle. I hope all those watching or helping to create this valuable content are doing well and taking good care of themselves throughout this tumultuous springtime. Our parasitology instructor (Dr. Bell, who is cc’d) introduced us to TWiP and challenged us to make a guess. Besides the opportunity to practice our investigatory skills, the incentive is a raffle entry for a hard copy of our parasitology textbook. A chance to flip through those glossy full-page pictures is just too good to pass up, so I started looking into Malaysian parasites. As an amateur, I decided to rule out GI helminths because the patient is not passing worms or having diarrhea/vomiting. He also doesn’t have a rash or hepato/splenomegaly so I crossed out scrub typhus as a possibility. Although it isn’t a very flashy diagnosis, I think he could have malaria caused by Plasmodium knowlesi. The patient’s anemia is indicative of a hemolytic condition, and we learned in class that P. knowlesi has a characteristic 24-hour fever periodicity. His elevated levels of aminotransferase and creatine could also align with malarial sporozoites infecting the liver, entering the bloodstream, and making the kidneys work overtime to filter dead or damaged blood cells. There are also macaques found in the Sarawak rainforest known to carry this flavor of malaria, and an incubation period of two weeks is reasonable. Of course, these symptoms could match plenty of illnesses, so I hope I haven’t fallen into an obvious trap. I also wish that this poor patient at least got to see the animals he was looking for before becoming ill. Thank you for considering my guess, and I’ll be looking forward to the next few episodes!

Sincerely,

Charlotte M.

Christian writes:

Hello dear TWIP team,

warm greetings from Basel.

I hope I have the right case.

This patient most likely has a P.knowlesi infection. It fits nicely with the incubation period, the daily fevers, the lab results, most likely the blood slide and importantly his visit to the jungle.

It would be interesting to see what was seen on the blood slide, as P. knowlesi can look like a mixed infection of P. malariae (band forms) and P. falciparum (multiple ring forms in one erythrocyte). 

It is the new up and coming kid on the block with rising case numbers in South East Asia and its daily cycle can quickly lead to a life threatening disease. It is also throwing a bit of monkey wrench into the gears of malaria eradication in this area as it is a zoonotic disease, and treating all the monkeys is challenging and getting rid of them not an ethical option. 

Treatment with a ACT would be the treatment of choice. 

Best Wishes,

Christian 

Thomas writes:

Hello Twipers,

Long time twiv listener, new to parasitology but figured id give it a shot!

I believe this person has malaria, and according to google Plasmodium knowlesi is the species found in malaysia. The impacted white blood cells and anemia tipped me off, plus the blood smear test suggestion.

No need to put me in a book raffle as I have no space for it unfortunately.

Also I dont think you do picks on this podcast but I saw this youtube channel called wormtalk94 mentioned on  H3H3 the other day, they post educational video on parasites so I figured your audience (here or on twiv) might be interested. I even saw they have a video on screw worm which i believe is of interest to the crew. link to the channel -> https://www.youtube.com/@WormTalk94

Hope all is well,

Thomas

Ps. I miss dickson 

Jenny writes:

The gentleman presents with clinical manifestations of malaria – the periodic fevers, anemia, and elevated liver enzymes. I used “CTRL F” to search Parasitic Diseases 7 for the keyword ‘orangutans’ and was rewarded with a mention of the 5th species of Plasmodium known to infect humans, Plasmodium knowlesi, so that is my guess.

Very best, Jenny

Jason writes:

Greetings TWiP hosts! 

In Episode 257’s Case of Fever in the Tropics, the patient with daily fevers,  pancytopenia, and exposure to the Malaysian jungle containing monkeys should be assumed to be infected with Plasmodium knowlesi malaria. 

The adage “Fever in the tropics is malaria until proven otherwise” applies to this case, and a thick/thin blood smear should be immediately assessed under 1000x oil microscopy for presence of intra-erythrocytic parasites. Plasmodium knowlesi malaria infects both humans and monkeys in Southeast Asia, and the daily fever spike is characteristic of this species, making this the most likely diagnosis. 

If microscopy reveals malaria trophozoites and schizonts with Sinton and Mulligan stippling, then the diagnosis of P. knowlesi is all but confirmed. 

However, if microscopy shows trophozoites exhibiting accole ring stages and Maurer’s clefts, and with a paucity of schizonts, then two tertian replicative cycles of P. falciparum would be my diagnosis.

Worm regards,

Jason in Seattle

Jay writes:

Dear TWiPozoites,

December. The rainy season in Sarawak. Not the best time of year to see proboscis monkeys. It’s hard to see through the mist. And puddles of rainwater make a good breeding ground for mosquitoes and the parasites that live within them.

One of the things I love about this podcast is the way you consistently point out that good science requires the ability to admit when one is wrong.

We were wrong about malaria. Until around 2004, we were taught that only 4 species of plasmodium cause malaria in humans. There are a couple hundred other plasmodium species, but the diseases they cause were thought to be limited to other animals such as birds, reptiles, and monkeys. Plasmodium knowlesi was first identified in 1931, and it was thought to infect only certain species of monkeys, including the proboscis monkeys of Malaysia. For a time, P. knowlesi was thought to be harmless enough that people were intentionally infected with it as a cure for syphilis.* The thinking was that the fever caused by P. knowlesi would kill off the spirochetes without killing the human host.

Decades after P. knowlesi was first identified, astute medical scientists in Malaysia, armed with more sophisticated diagnostic technology, discovered that it does cause disease in humans. A lot of disease. There were 2,500 cases reported in Malaysia in 2022 and 9 deaths.

So medical science had it wrong from 1931 until 2004. And being wrong is ok. It’s part of the scientific process. We keep pushing on, two steps forward, one step back. That’s how science works, and it needs our support. Are you listening, Mr. Kennedy? 

Thank you as always,

Jay

*Van Rooyan CE, Pile GR. Observations on infection by Plasmodium knowlesi (ape malaria) in the treatment of general paralysis of the insane. Br Med J 1935;2:662

Jay Gladstein, M.D. | Chief Medical Officer
APLA Health & Wellness
Olympic Medical Clinic | Los Angeles, CA 90036

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

Dear Twip hosts,

The symptoms described in the last episode in a young man in Kuching, Malaysia bring up two immediate thoughts: malaria & dengue. And since it’s not dengue, given the location of the patient, it smells a lot like malaria knowlesi infection.

​​Plasmodium knowlesi is a zoonotic malaria parasite primarily found in long-tailed and pig-tailed macaques in Southeast Asia. It was initially considered rare in humans until a significant outbreak in 2004 in Malaysian Borneo highlighted its prevalence. P. knowlesi. The parasite is transmitted by Anopheles mosquitoes. Clinical manifestations range from asymptomatic to severe malaria – with a case fatality rate of 1-2%, if diagnosed and treated correctly. Misdiagnosing Plasmodium knowlesi as P. malariae can be fatal because P. knowlesi replicates rapidly and can cause severe disease quickly, while P. malariae is typically mild and slow-progressing.

Diagnosis is challenging due to its morphological similarity to P. malariae, necessitating molecular methods like PCR for accurate identification. Treatment typically involves artemisinin-based combination therapy for uncomplicated cases, while intravenous artesunate is recommended for severe infections.

Thank you for this great case! All the best,

Michelle and Alexander from the First Vienna Parasitology Passion Club

Keira writes:

Hi TWIP team!

Greetings from Seattle, Washington! I am a new listener to your podcast; my parasitology professor at the University of Washington recommended your show and despite my freshness to the world of parasitology, I’m going to take a guess.

I believe this patient is suffering from malaria, caused by Plasmodium knowlesi. This is due to the patient’s 24-hour fever cycles accompanied by chills, headache, and nausea. Importantly, P. knowlesi is endemic to the Malaysian region. This species of malaria is known for causing daily fevers, distinguishing it from other Plasmodium species, and is often misdiagnosed. 3x thick and thin blood smears should be done to confirm this diagnosis (shoutout Dr. Naula for requesting this test!). 

Thank you for the opportunity to test my knowledge!

Warmly,

Keira

John writes:

Greetings distinguished hosts, I’m still trying to win the book. 

A quick note, you’ve turned this layman into a frequent correct guesser and I attribute that entirely to learning from you hosts and the other astute guessers who add many details unknown to me and expand my thinking into the landscape of parasites.  I still get minor details wrong but I gain so much from the interaction between the audience and you hosts.

Back to this case, malaria came to mind and that steered me to look at falciparum, vivax and knowlesi with an emphasis on the latter association with primates.  I rewatched Parasitic Diseases lectures 12&13 and Dickson displayed a thin and thick smear which Christina asked about, and he also stressed that knowlesi is about location location location which is satisfied here.  Anemia is present and lines up with destruction of erythrocytes, also heart rate and breathing increased and distressed, low platelets (below 150k per uL) and abnormal coagulation can all be associated with disease as is daily fevers and shaking chills.

I tried to rule out trypanosomiasis, babesiosis, chagas, leishmaniasis, and toxoplasmosis and didn’t find any reason to consider them before malaria.

The lectures and recent CDC (2024) had guidance on treatment which said that there has been no widespread evidence of chloroquine resistance with respect to knowlesi so both cholorquine and hcq may still be used.  Severity can determine oral vs intraveneous with ACTs also mentioned elsewhere.

December is in the date range for this parasite in the region, going to the zoo would allow primate associated knowlesi and if the family was separated at the zoo this wouldn’t transmit person to person after infection.  I will go with Dickson’s “location location location” and guess P. knowlesi

PS Daniel is a hero for recording after surgery, what an iron man

—

John

Joseph writes:

Greetings from Cut & Shoot, Texas (yes, it is a real place)! 

While I have been a listener of all things microbe.tv since 2016, this will be my first time taking a crack at a TWiP case. Thankfully, I have my digital copy of Parasitic Diseases 7th Edition, Medical Appendix and the interwebs to guide my thought process. I have worked in a clinical lab for 20 years and have been an infectious disease nerd for just as long. I am currently a Laboratory Safety Specialist at MD Anderson Cancer Center and hope to make my way to infection control. I just applied to Texas A&M University for their master’s in public health with a focus in Infectious Disease Epidemiology and hope to start the program this Fall. 

Let me cover the details of Dr. Griffin’s clinical description of the man from Kuching presenting with persistent fever and chills. Upon his visit to the hospital, his heart rate and respiratory rates were increased. Labs showed that the patient was thrombocytopenic with abnormal coagulation studies, and elevated creatinine and aminotransferase. The patient had visited the jungle to see orangutans two weeks prior to onset of symptoms. It was mentioned that other types of primates may have been present in the area in which he was visiting. 

With this information, I am going to guess that the patient has malaria caused by P. knowlesi. The patient was often out in the evening during his trip, which increased exposure to mosquitoes – particularly Anopheles latens that are found in Sarawack.  Combine this with the presence of primates, and you have a recipe for a zoonotic P. knowlesi exposure. Furthermore, the incubation period, physical symptoms and lab findings fit malaria. While these symptoms could easily point to P. falciparum, the fever pattern seems more frequent and at regular 24-hour intervals, which points more towards P. knowlesi. Again, the presence of primates was the key indicator for my diagnosis.

This was a fun case to look into. I hope it lands me a physical copy of Parasitic Diseases to proudly display in my office. I truly enjoy the time and energy you put into these podcasts. I am a firm believer that GOOD science should be accessible to everyone. I look forward to new episodes popping up in my podcast feed, and I often tell others to tune in to grow your audience and exposure. I also want to give my condolences regarding the passing of Dr. Despommier. He was a joy to listen to and learn from. He will be sorely missed.

Kind Regards,

Joseph Jacobs, MLA(ASCP)CM, QLSCM

Frithjof writes:

Dear Professors,

Greetings from Caen, Normandy where the weather is very pleasant and sunny these days. The patient experiencing daily fevers after a trip to the jungle near Kuching probably is suffering from Malaria caused by Plasmodium knowlesi which is endemic to the island of Borneo. A blood smear should be performed as soon as possible, and if available, PCR testing can confirm the species due to morphological overlap with P. malariae. Recommended treatment is artemether-lumefantrine, which is effective for uncomplicated P. knowlesi malaria.

Thank for this interesting case, I am looking forward to next month when another TWiP is PARASITIC!

Frithjof (Proud owner of a signed copy of „Parasitic Diseases)

Paul writes:

Returning Book Winner: 

My comment about “vocabulary review” in the last case referred to learning about Wolbachia being an “obligate endosymbiont” of Brugia malayi. 

My solution to the current case is Plasmodium knowlesi malaria.  This is the most common zoonotic malaria in the Sarawak region. 

Three time-related clues: daily fevers on a 24-hour cycle, the subject being outside in the evening when anopheles mosquitos are active, and the case occurring in December during the rainy season month with more mosquitoes. 

The clinical findings are consistent with P. knowlesi disease: the low platelet count which is a nearly universal finding, and fevers on a 24-hour cycle. Coagulation, liver and kidney abnormalities are common in malaria. 

Thank you for all your work in science education and advocacy! 

Dr. Paul

Kat writes:

Dear TWIP hosts,

Hello from Melbourne Australia, where the weather is certainly turning autumnal.

I’m a long time listener but this is my first time writing in! I’m a former music teacher turned wildlife biologist, and my fascination with parasites was sparked by a first year microbiology elective I took when I returned to university, a few years back. That said I am very much a layperson and may be totally off with my guess. 

My guess is malaria caused by Plasmodium knowlesi. My reasoning for this diagnosis is that firstly, my research tells me that malaria is one of the more common diseases in Borneo, particularly outside the urban areas, and that it is caused by mosquitos that are more common at night. I believe the patient was going out in the jungle at night and that the trip was during December – I’m guessing the mosquitos may also thrive more during the rainy season. Secondly, the patient was out looking for monkeys that can be infected with this species of Plasmodium as well. Thirdly, the symptoms of shaking chills, headache, nausea and elevated heart rate and respiratory rate seem congruent with P knowlesi malaria and this type of malaria seems to cause fevers that spike daily, which was also experienced by the patient. Also, I believe I’ve heard Daniel say the words, “malaria until proven otherwise”!

Thanks so much to the three of you for providing such wonderful education. Lately I have been taking long drives at night to do fieldwork tracking platypus movements, and your voices have kept me good company!

All the best,

Kat

Ellen writes:

Dear Daniel, Christina and Vincent (no particular order),

Thank you for another interesting case. I have been listening to TWIP since the pandemic, when I found some time.

About the new case presented in episode 257, a male contracted a parasite resulting in fever, chills, headache and presumably anaemia after visiting orangutans in the jungle of Sarawak – this is caused by Plasmodium knowlesi. I have to confess that it is not completely fair for me to participate in this book competition, as I am a PI researching molecular mechanisms of red blood cell invasion by Plasmodium and Babesia parasites. 

Malaysia has made great progress in eradicating Plasmodium transmission, but P.knowlesi, a zoonotic parasite with a macaque reservoir, is harder to shift. Your podcast was timely for World Malaria Day (25th of April 2025), when we try to make the world and the world leaders and funders aware that we have come so far in reducing mortality and morbidity caused by malaria, and finally we have vaccines which can help us, so do not stop now funding the interventions we know that they are working and R&D!

In that context, Christina will probably be aware of VEuPathDB (https://veupathdb.org/veupathdb/app/), a critical database for all protozoan, vector, worm and fungi researchers. This does not only collate genome, proteome, transcriptome information of most eukaryotic pathogens, but also has critical software tools e.g. to identify new parasite ligands which could be novel vaccine antigens. Funding for this critical database has been stopped (surprisingly unrelated and ahead of the current US administration) and like other bioinformatic resources and databases, is now imminently under threat of being switched off.  Please see here (https://www.linkedin.com/posts/veupathdb_the-veupathdb-survey-asked-users-to-estimate-activity-7302764760826040320-jdH_/). The research community is currently trying to 1. contribute money for each lab using the resource and 2. fundraise to keep it online. I started my career before the Plasmodium genome was completed and published and remember been given a ~12 kb gene sequence printed on paper to use to design primers. It wasn’t fun working that way, and I do not want us to have to return to something that rudimentary. A shoutout from you asking all eukaryotic pathogen researchers to contribute and funders to come to pathogens’ research rescue would be a great help. Thank you!

Best wishes from a beautiful 18C, sunny, wider London area,

Ellen

Senior Lecturer in Vaccinology

The Royal Veterinary College

Hatflied UK

Justin writes:

Hello dear hosts,

Unfortunately, I did not have time to make a guess last month as I was preoccupied preparing for my master’s defence, but after successfully defending I am ready to start guessing again.

In the case of the man in his thirties presenting with a daily cyclical fever and thrombocytopenia, two weeks after visiting the jungle, I believe the patient has contracted Plasmodium knowlesi. P. knowlesi is the most common cause of malaria in Malaysia, and, as with most cases of fever, check for malaria first. I couldn’t find any connection to orangutans or proboscis monkeys, but it certainly is known to infect macaques which likely live in close proximity.

Thanks for another great case, and hoping to win a book,

Yours,

Justin

Eyal writes:

Dear Vincent and the sages of the eukaryotes.

Greetings from Sydney Australia and the land down under, where Fall is here and the rain is constant…

For the case of the man in his 30s from Kuching.

Based on jungle exposure, intermittent fevers, low white blood cell count, anemia, and thrombocytopenia I believe the culprit is Malaria. Specifically, based on the location in Borneo and the short time between exposure and symptoms, and the severity of the symptoms, I believe the man has been infected with Plasmodium knowlesi.

Based on the comment that the patient is a little nauseated but is not vomiting I believe he tolerated treatment with artemether-lumefantrine and I hope has recovered well.

As always, thank you all for the learning opportunity and the knowledge you share.

Eyal,

Returning champion (would love to have an opportunity to win Vincent’s virology textbook in the future :)).

Felix writes:

Dear hosts,

looks like the trip to the jungle was infectiously fun. This gentleman presenting with tricytopenia and what sounds like positive sepsis criteria in labs would have me really worried. I think the air in the jungle must have been bad. My guess for this case is Malaria caused by Plasmodium Knowlesi because of the specific anamnesis and the location. 

Greetings 

Felix

Kate writes:

Hello from England where the spring sunshine is bringing optimism and smiles after all the cold, rainy days of winter. 

I am an anaesthetist (also known as an anaesthesiologist in the USA), in my fifth decade, and have come across your podcast while taking the GHHM course with Medecins Sans Frontieres over the last six months. I took part in a half day case-based seminar hosted by Daniel for the University of Glasgow, and have listened to lectures expertly delivered by Christina, and I’ve been hooked ever since. The subject matter could not be more different from my day job, and learning entirely new things at my age has been a revelation! The parasitology textbook, while appearing onerous from the outside, actually reads like a story written by a parent talking about much-loved children, and the obvious fascination with all things parasite has rubbed off on me. This is the first time I have written in, so please bear with me as I apply my newly-acquired knowledge. 

I think our Malaysian patient may be suffering from a malaria infection, and the symptoms and situation fit with this being plasmodium knowlesi, which I believe to be the most common malaria type in this part of the world.  This parasite is delivered to humans by anopheles hackeri mosquitos, found in forested areas of South East Asia, but is more commonly found in monkeys, particularly the long-tailed and pig-tailed macaques and Sumatran surii, rather than humans. December is considered the wet season in Borneo, which would make these mosquitos more prevalent. The red blood cell part of the life cycle of this parasite is around 24 hours in length, which would explain his cyclical fevers, and the short life cycle can lead to high levels of parasitaemia within a short time. His symptoms would lead me to class his infection as potentially severe. I would expect to see parasites on a Giemsa-stained thick blood film, and to be able to ascertain their identity on a thin blood film. However, knowlesi trophozoites can resemble both p.falciparum and p.malariae in morphology, so if the resources allowed, I would want to check my diagnosis with a PCR test too.  Uncomplicated infections would respond well to artemisinin combination therapy similar to other malaria subtypes, but in this case I would like to consider treatment with intravenous artesunate first due to the severity of his symptoms at presentation. His blood work fits with a malaria diagnosis; we do not know how severe his anaemia is but the raised creatinine would concern me as a marker for kidney injury, and I would like to know more about his coagulopathy as severe malaria can initiate DIC. 

I have once visited Borneo myself, to climb Mount Kinabalu, and was then blissfully unaware of the presence of this parasite, and many others, that may have sought me out. I am finding that my more recent travel plans do consider much more highly which infections I may expose myself to; perhaps a potential disadvantage of my new interest! 

I would very much like to be placed in the draw for the signed textbook, please. 

Thank you for your longstanding commitment to educating others in all things parasite.

With best wishes

Kate

Dr Kate Paterson

Consultant in Anaesthesia

Royal Berkshire Hospital, Reading. England.

Henrik writes:

Dear knowlesi-very-much hosts,

I write to you about the case of the Sarawak resident who presents with fever, thrombocytopenia and organ function impairments one should think about an infectious disease fast. 

Bacterial infection leading to Sepsis is also a possibility and should be ruled out (or treated empirically if no other probable cause exists).

Fever, thrombopenia and anemia are however also signs of an infection with a Parasite of the Plasmodium genus.

Fever patterns can, but not must, predict the type of infection.

There are 1-day (daily = latin quotidien) in knowlesi, 2 day (theoretically I believe) in falciparum, three for ovale and vivax and four for Pl. Malariae patterns.

As Malaysia has mostly P. Knowlesi since 2018 and this is also known as the “zoonotic malaria”, I would suggest Malaria quotidiana caused by knowlesi in this patient. It is difficult to differentiate from P. malariae on the blood smear, so PCR might make sense.

P. knowlesi can lead to higher parasitemias, similar to P. falciparum. Therefore, I would suggest inpatient Management. Severe malaria should be treated with IV Artesunate followed by consolidation treatment. If the clinical Picture is not as severe, artemisinine-combination treatment can be considered.

Thank you for the interesting case!

Best,

Henrik

The University of Oklahoma Parasitology Class writes:

Dear TWiP team,

Greetings from the undergraduate parasitology class at the University of Oklahoma. The weather here this morning in Norman is 66 F (18 C), and sunny, and for the moment it is not very windy.

In the case of the man who visited a jungle site in Borneo, we believe he was infected with Plasmodium knowlesi. The location, malarial symptoms, and the presence of monkeys immediately suggested this parasite. The daily fever cycle is specific to P. knowlesi, and headache, low platelet count, anemia, and other laboratory results are consistent. December would have been right in the middle of the rainy season for Borneo, so mosquitoes would be plentiful. Macaques are the usual reservoir host associated with P. knowlesi, and they aren’t specifically mentioned as being present, but at least two species of macaque are found in Sarawak state.  Our quick review of the literature suggests that other monkeys, including the proboscis monkeys (Nasalis larvatus) Dr. Griffin mentioned, could also be reservoirs. The rest of the man’s family are not sick, but they were outside less and would likely have encountered fewer mosquitoes.

We did consider lymphatic filariasis as a possibility, even though that was the previous case, but we found no discussion of that having a periodicity to the fever, nor were other symptoms consistent. Other parasitic causes of fever were more likely to be the result of exposures in food, and Dr. Griffin said he hadn’t eaten anything unusual.

The University of Oklahoma Parasitology Class

Michelle Vang

Takarah Robinson

April Grigsby

Kalista Magana

Elizabeth Foreman

Harley Petty

Brook Patrick

Anna Reid

Madison Rightmire

Ashlynn Luther-Chapman

Aysha Prather, Instructor

Rod writes:

Hi all at TWiP

With regards to the gentleman that has been admitted to hospital in December in Malaysia. I suspect from the details of his signs and symptoms that he is suffering from a form of malaria- judging by the fact that he has daily fever and low platelet count and respiratory distress, and has recently visited an area of jungle- he could be infected with Plasmodium knowlesi- a zoonotic form of malaria that can spill over from monkeys to humans- transmitted by Anopheles mosquitoes. Microscopic examination of blood may reveal parasites, though if plasmodium parasites are observed pcr should be used to confirm the species as P. knowlesi can resemble P. malariae. Treatment could commence with chloroquine in combination with other anti malarials such as artemisinin based drugs.

Regards from North Portugal,

Rod

Ben writes:

Dear Twippers,

The patient has malaria caused by Plasmodium knowlesi. 

I entered: “proboscis monkeys parasites that causes daily fevers” into Google. The AI summary immediately spit out the pathogen species. The symptoms otherwise match P. knowlesi malaria. The lack of an enlarged spleen may be due to this being an early infection. Although I am not at all certain on that point. 

I do get a kick out of Dr. Griffin still pronouncing the diacritic marks that used to be over Aedes. 

From partly cloudy Liverpool,

Ben (returning champion)

Albert writes:

Greetings TWiP,

I’m Albert Ling, Internal Medicine Physician from Tampin, West Malaysia.

Thank you for the excellent sharing on filariasis!

I’d like to share my thoughts on the case presented:

A previously healthy man presented with intermittent fever, chills and fatigue after a trip to a nearby jungle in Kuching, Sarawak, where he had close encounters with Orang Utans. He was found to have pancytopenia and multiorgan failure.

Given the history of jungle exposure and contact with monkeys in Borneo, I suspect severe zoonotic malaria (Plasmodium knowlesi)

Differential diagnoses include scrub typhus and leptospirosis.

P. knowlesi now accounts for approximately 70% of malaria cases in Malaysia.

It replicates every 24 hours, much faster than other Plasmodium species (typically 48–72 hours), leading to rapid clinical deterioration.

An urgent thick and thin blood smear is crucial for diagnosis.

The patient requires ICU admission for close monitoring.

Once confirmed, Artemisinin Combination Therapy should be started promptly.

Fun fact: Artemisinin is derived from a traditional Chinese medicinal herb and its discovery earned Tu Youyou a Nobel Prize for its groundbreaking impact on malaria treatment.

Please do visit Borneo! We don’t just have filaria and malaria—we also have amazing people, breathtaking nature and delicious food!

Just don’t forget your chemoprophylaxis before the adventure!

Warm regards,

Albert Ling