Diseases without vaccines

Four deadly diseases that you can't immunise yourself against.

There are a number of diseases researchers are still trying to find vaccines for. Here we investigate four viruses and give you an update on where the experts are at.

1

Malaria

Malaria is one of the most deadly infectious diseases in the world. Each year there are 250 million cases worldwide, and 863,000 deaths. One in five childhood deaths in Africa is from malaria.

Australia was certified as malaria-free in 1981, however there are still hundreds of cases here each year in people who catch it overseas. While there are a number of anti-malaria drugs, malaria parasites in some parts of the world have developed resistance to these.

Symptoms

Sufferers have a fever, headache, and vomiting, with symptoms usually appearing between 10 and 15 days after the mosquito bite.

A vaccine?

Earlier this month researchers from Griffith University in Queensland said they believed they have discovered a malaria vaccine. PlasProtecT uses low doses of the parasites, put to sleep using a chemical treatment. The first phase of the human trials will take place in the next 12 months.

2

Dengue Fever

Dubbed 'breakbone fever' dengue fever is transmitted by the bite of a mosquito carrying it.

There is no vaccine against dengue fever, there are no drugs you can take to protect against it, and there is no cure. All doctors can do is treat the symptoms. It can be deadly.

Last year there were 1,201 cases of dengue fever in Australia.

Symptoms

Symptoms begin around a week after being bitten. They include aching in muscles and joints, a high fever, fatigue, a rash and intense headaches. The symptoms last for around a week, but sufferers can still experience fatigue months later.

A vaccine?

There are four strains of the virus, which means a vaccine needs to ideally cover all of them. Earlier this year, as part of the Eliminate Dengue Project, specially bred mosquitos were released in Cairns infected with the natural bacteria wolbachia, which is thought to stop the insects from transmitting dengue fever.

The idea is that they mate with dengue mosquitos and eventually all mosquitos will carry the bacteria – making them unable to give people dengue.

"If these initial trials are successful they will be followed by similar trials in Vietnam towards the end of 2011," said Professor Scott O'Neill, from Monash University.

3

Ross River (RRV)

Ross River virus is a non-fatal infectious disease spread by the bite of a number of different species of female mosquitoes. Last year 5,141 people were infected with RRV.

The number of cases of RRV are gradually increasing, according to Professor David Gordon, Flinders Head of Microbiology and Infectious Diseases.

"People travel go home infected, get bitten by another mosquito and then that mosquito can spread it to other people." says Professor Gordon.

Symptoms

It can take up to two weeks for sufferers to develop symptoms, these include joint pain, stiffness and swelling, as well as a flu-like illness and a rash. Some sufferers have joint welling and fatigue for months.

A vaccine?

Researchers are testing a vaccine at the moment across Australia in a trial, led by Professor Gordon.

"The vaccine is well on the way," says Professor Gordon. "The trial is likely to finish in about two months."

4

Chikungunya

Chikungunya virus is a mosquito-borne infection that largely occurs in Africa, Asia and India. There have also been cases reported in Australia of people who caught the infection while travelling abroad, then returned home. There were 54 cases here last year – almost double that of the year before.

There are no specific drugs to cure the disease, treatment is primarily focused on relieving the symptoms.

Symptoms

Symptoms are similar to those experienced in dengue fever, including fever accompanied by joint and muscle pain as well as headaches, nausea, fatigue and a rash. The symptoms last usually for a matter of weeks, but the joint pain can persist for years.

A vaccine?

There is no commercial chikungunya vaccine, although a vaccine trialled on monkeys last year appeared to work.

"At a time when there are no commercially available vaccines ... a virus-like particle vaccine has the potential to have a considerable impact on the spread of this disease," wrote American researcher Dr. Gary Nabel in the journal Nature Medicine. source: bodyandsoul.com.au