Biological life cycle

• More than 700 cases of this gastrointestinal disease were reported in Queensland in January, which is 13 times more than in January last year.
• Read more:
  What lies beneath: the bugs lurking in your swimming pool

What causes cryptosporidiosis, and who is affected?

• Cryptosporidum hominis only affects humans and is the major cause of recent outbreaks in Australia, while Cryptosporidium parvum can also affect animals.
• The infection is spread by spores called oocysts in the stools of humans and animals.
• Cryptosporidiosis is more prevalent in young children, particularly those under five, but the disease can affect people of any age.

So how do we catch it?

• The largest recorded outbreak occurred in Milwaukee in 1993 where 403,000 people were believed to have been infected.
• As few as ten oocysts can cause infection, making it possible for contaminated drinking water to affect a very large number of people.
• Oocysts have been found in foods such as fresh vegetables and seafood but these are not common sources of infection in Australia.

What about chlorine?

• Young children and in particular children in nappies are known to increase the potential for disease transmission in recreational water.
• Proper nappy changing, frequent bathroom breaks and showering before swimming to remove faecal residue are helpful ways to reduce the risk.

Some sensible precautions

Other measures you can take to reduce yours and others’ risk of cryptosporidiosis include:
avoid swimming in natural waters such as rivers and creeks during and for at least three days after heavy rain
avoid swimming in beaches for at least one day after heavy rain
avoid drinking untreated water such as water from rivers or springs. If you need to drink untreated water, boiling it first will kill the Cryptosporidium
avoid swallowing water when swimming if you can
if you’ve had diarrhoea, avoid swimming for at least two weeks after it has resolved
avoid sharing towels or linen for at least two weeks after diarrhoea has resolved
avoid sharing, touching or preparing food that other people may eat for at least 48 hours after diarrhoea has resolved
wash your hands with soap and water after going to the bathroom or before preparing food (Cryptosporidium is not killed by alcohol gels and sanitisers).
Not all cases of diarrhoea are due to cryptosporidiosis. There are many other causes of infectious gastroenteritis and because the vast majority of the time recovery is uneventful you don’t need to see a doctor unless very unwell. If you do suspect you may have cryptosporidiosis you can ask your doctor to refer you for a stool test.
Vincent Ho does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

• Trials have shown that the R21/Matrix vaccine, developed by Oxford University together with the Serum Institute of India, reduces malaria by up to 75%.
• The Conversation Weekly spoke to chief investigator Adrian Hill, who is also director of the Jenner Institute at the University of Oxford, about this revolutionary vaccine.

Why is the R21/Matrix vaccine a game-changer?

• The best vaccine prior to this was about 50% over a year, and lower than that over three years.
• The big difference is how you can manufacture it at a scale that is really needed to protect most of the children who need a malaria vaccine in Africa.
• There are about 40 million children born every year in malaria areas in Africa who would benefit from a vaccine.

Why has developing a malaria vaccine been so difficult?

• Malaria is not a virus, it’s not a bacterium.
• This is one of the reasons that malaria is super complex.
• If you can get a really good vaccine for one of those, you will break the cycle of transmission.
• It’s a silent infection until it gets into the blood and starts multiplying inside your red blood cells.
• So the sporozoite is a natural target to try and kill the parasite before it multiplies very quickly.

Tell us about past attempts to develop a malaria vaccine

• In about 1943, there was a trial of the whole malaria parasite vaccine candidate in New York with zero efficacy.
• And then within 10 years we had 5,000 candidates because everyone hoped that the gene they had sequenced might be a malaria vaccine.

Why aren’t vaccines for whole parasites effective against malaria?

• It’s the same reason that just getting infected once by malaria doesn’t give you protection against the next infection.
• In the areas of malaria where we test our vaccines in Africa, some children get up to eight episodes in three or four months.
• They get quite unwell with the first and three weeks later they’re having a second bout and so on.

Will we ever eradicate malaria entirely?

• Malaria is very high on the list of diseases we want to eradicate.
• I don’t think it’s going to happen in five years or 10 years, but it should happen in something like 15 years.

• If combined with the new target PfCDPK-5 and PfSEA, the vaccine has the potential to shut down the parasite at multiple points in its cycle.
• In coming months, Dr. Kurtis will work to optimize the formulation of his vaccine prior to IND submission and first in humans testing.
• This medicine will be an additional focus of Ocean Biomedical’s development pipeline in 2023 and will address a massive unmet need.
• “Falciparum malaria is a leading cause of death in children world-wide and our global malaria treatment strategy relies almost exclusively on artemisinin-based drugs.