Dextran 40 - New hope for dengue patients

By Manjula FERNANDO

The Health Ministry has begun dispatching the drug - Dextran 40, a new intravenous fluid that can be administered to critical dengue patients, to hospitals islandwide. Health Ministry’s Medical Supplies Division Director Dr. Kamal Jayasinghe said the drug is like ‘saline’ but it has to be administered with caution as it can cause side effects like kidney damage. The Government bought down an initial stock of 300 bottles of Dextran 40 from Thailand and the WHO provided them with another stock of 1250 bottles. “We will be taking action to order more as per the need. This drug can be used only on critically ill patients under strict supervision,” he added.

A Consultant Paediatrician attached to the General Hospital, Gampaha Dr. A. Lak Kumar Fernando said Dextran 40 is no miracle cure for dengue but is an effective intravenous fluid that can help control dengue related deaths.

Dr. Fernando was among the team of six doctors sent to Thailand by the Health Ministry last May for training on the new treatment and management strategies of dengue. (Three more doctors were sent to Thailand last month for training.)

The saline type of drug, a plasma expander, helps avoid fluid overload in patients who are otherwise likely to develop this complication during usual treatment of ‘Shock’ - one of the major causes of death in dengue patients.

Dextran 40 has proved its effectiveness and is widely used in Thailand where the prevalence of dengue was nine times more compared to Sri Lanka during 2009. There is still no specific cure for dengue.

The Sunday Observer interviewed Dr. Fernando in a bid to clear up any misconceptions over dengue fever and the new drug. The following are excerpts from the interview:

There are two types of dengue. Dengue Fever and Dengue Haemorrhagic Fever. With dengue there is no risk of death. Majority of patients recover with symptoms of a mild flu and mostly with no symptoms at all.

If you take 10,000 people who will get infected with dengue virus, 9,000 may not even develop a fever. They will be asymptomatic.

Only 1000 of them will have a mild fever. Out of this, 500 patients will show symptoms of an ordinary viral infection. A self limiting fever, but they will not show symptoms synonymous with dengue.

Another 400 will develop Dengue Fever (DF). They will recover completely without any complications. These 400 may have reduced platelets counts, experience bleeding which is indicated by red patches on the skin, minor gum and nasal bleeding, a red colour rash, mild vomiting. This category of patients will also recover without any special care. Fifty per cent of these patients will experience platelet counts dropping below 100,000.

Vulnerable group

The balance 100 patients of this initial 10,000 infected with the virus have a chance of developing the fatal Dengue Haemorrhagic Fever (DHF). This is the vulnerable group that needs special clinical care.

When a patient is down with dengue, the symptoms will be there from third to tenth day. When a patient develops DHF, high temperature is an essential feature.

Can a patient not have critical symptoms but die of dengue?

If someone says a patient died of DHF but showed none of the critical symptoms, that is far from the truth.

Either you have heard a second hand story where the facts got twisted somewhere down the line, or they have not bothered to check the temperature with a thermometer. It could also be the individual perception of how they define high fever.

It is highly uncommon to associate a mild fever with DHF.

During the course of our research into all the 64 dengue deaths reported in Gampaha district, we heard the patients all reporting the symptoms associated with DHF. We did personal visits to every household to collect data.

DHF patients

Patients with DHF should be treated differently because during the course of the illness they may suffer leakage of plasma through their tiny blood vessels. This leakage lasts for 48 hours.

After two days of fever (between third to seventh day), the patient is at the risk of developing the leakage of plasma. This will deprive the blood stream of fluid resulting in a low blood pressure and a drop in the pulse volume. The Patient will then go into ‘shock’. When this happens to a very severe degree it is called Dengue Shock Syndrome (DSS).

When a patient develops this condition, all his vital organs, Liver, Kidneys and Brain get affected since there will not be enough blood circulation. If the patient is not treated for ‘shock’ for four hours he will certainly suffer liver failure and if not treated for ten hours he will certainly die.

Prolonged shock

Prolonged shock is one of the causes of death in Dengue. The treatment for this is to administer saline to replace the lost fluid and restore circulation.

During the leakage, when you administer ordinary normal saline, part of that will also seep through from the wall of the blood vessel out into the Peritoneal or the Pleural cavities.

This condition also affects the lungs due to fluid retention and Dengue patients at this point develop breathing difficulties.

The leakage of saline and the patient’s own plasma can give rise to other complications known as fluid overload. This is the other cause of death in Dengue.

The leakage of plasma lasts for 48 hours and then it stops. This fluid then gets absorbed back into the system at the end of the 48 hours when leakage stop. This can cause heart failure and death. Two to five in 10,000 people infected with the dengue virus show this severe degree of DHF.

Therefore, giving too much of ordinary saline or plasma transfusions or even platelet transfusions that has significant volume of plasma with it during this critical 48-hour period of leakage phase can be detrimental to some patients.

Dextran 40, a plasma expander is useful for patients in this category. This drug with high molecular weight does not leak as easily as saline. The doctors can substitute saline with Dextran 40 at the height of this condition - when the leaking is at its peak. During this phase it takes just 1-2 hours for a bottle of saline to seep through completely. But Dextran slows down this process due to its ‘osmotic pressure’.

Need strict supervision

This drug, however, should be administered under strict supervision.

Not more than three doses of Dextran 40 can be administered within a period of 24 hours since it can affect your kidneys. This cannot substitute Saline completely.

Dextran 40 is not a magic drug that can cure dengue. This is used to treat patients in a severe stage of DHF. Around 60 percent of dengue shock patients will not need this drug at all.

The supply of this drug is also very limited because this is manufactured for limited and specific purposes. It takes about two months to get the goods delivered after placing an order.

Therefore, the Government should ensure to sustain the supply of the drug where initial stocks came to us with the help of the WHO.

Who is more vulnerable?

We cannot say if a certain group of people are more vulnerable to the disease. With dengue nature is in full control. Boosting your immunity may help you keep other diseases at bay but will do little to prevent dengue. Even the healthiest persons have died of Dengue.

Gaps in the best knowledge about best management methods of this rather unusual disease with shock is perhaps another contributor for a higher number of deaths in Sri Lanka. We are in the process of rectifying this flaw. Nine of us were sent to Thailand for training on new methods of treatment and management of dengue. We are imparting that knowledge to the local staff, doctors and the medical community.

In 1989 when Sri Lanka had its first major epidemic out of about 200 patients infected nearly 20 died giving a case fatality rate of 9 percent. Thailand had a 13 percent death rate during its first major epidemic in 1958In 2009 there were 35,000 reported cases of dengue with 350 deaths in the country with a case fatality rate of 1 percent. We have recorded 25,000 cases this year up to last week, along with 186 deaths.

Counter action yielding results compared to January with 4000 cases and 51 deaths there is some improvement in the death rate in July with 4000 reported cases and just 24 deaths. This may be an indication that the new methods of treatment now used in many hospitals in the country are showing some results. May be it is a bit too early to say about it but we will have to improve the treatment methods and also facilities for diagnosis and monitoring to receive better results.

In Thailand the full blood counts of a patient could be obtained in half an hour in a government hospital. We have to come to that level before we see even better level of survival rates for our patients.

Thai experience

Sri Lanka is taking a cue from Thailand in lowering dengue related deaths.

Thailand recorded its first dengue case in 1958 and the same year there were 2100 patients including 300 deaths.

They have a very strong preventive program. Still in 2009 there were 180,000 cases of dengue in Thailand but less than 50 died of the disease. The reason for this is their novel treatment technique and management strategies.

Although dengue is a bigger issue there, due to the lower mortality rate the disease hardly hit headlines in Thailand.

The simple answer is no. going by the world experience it is wise to manage the death rate than eradicating dengue. Dengue larvae can sustain without water for several months and spring up with the first drop of rain. The experts therefore are not over optimistic at the prospect of eradication.

Nearly 2.5 million people worldwide get infected with dengue every year.

Q: There is this rumour that papaw juice is a good home remedy to fight dengue. Has this been proven scientifically?

A: There are such stories circulating in the Internet. But no hard scientific evidence to prove that ‘papaw juice’ boosts your platelet count. So it’s not a chance you can afford to take when dealing with a fatal disease like dengue.