Early intervention is best form of prevention :

Dengue: treatable, completely curable

By Carol Aloysius

Dengue is rising to epidemic proportions in the country, despite efforts to control its spread by health authorities.

Consultant Resident Physician Colombo South Teaching Hospital, Dr Asanka Ratnayake talked to the Sunday Observer on how the disease is caused, and the Do's and Don'ts for preventing complications.

Excerpts...

Q. Dengue is now rising to epidemic proportions. What has caused this surge especially in the Western Province?

A. Dengue is an urban and a sub-urban disease. This is because the aedes mosquitoes which spreads the disease thrives in highly populated areas as it feeds on human blood. Because it is a recurring disease, dengue fever is now considered endemic to Sri Lanka. Every year several thousand cases are recorded. It usually peaks in June and July when the South-west monsoons are active.

Q. Is dengue a viral disease or is it caused by a bacteria ?

A. Dengue infection is caused by dengue virus. It has a number of serotypes or subtypes all of which can cause fever and all have been seen in Sri Lanka. They are referred to as DEN 1, 2, 3 and 4.

Q. Is it infectious? How does it spread?

A. Dengue is an infectious disease. It is spread by mosquitoes belonging to the genus Aedes. In Sri Lanka Aedes aegypti and Aedes albopictus are the main culprits.

Of these Aedes aegypti is the principal vector. Once the female mosquito bites an infected human (only female mosquitoes bite humans as blood is required only for maturation of its eggs,) the virus passes on to the gut of the mosquito.

Over a period of about 10 days the virus replicates and passes from the intestines to the salivary glands of the mosquito. Human infection results from the bite of the infected mosquito.

The mosquito remains infectious for its entire 1-month life, and can transmit infection with as few as 100 viral particles.

Aedes aegypti mosquitoes most commonly bite at dusk and dawn, indoors, in shady areas, or when the weather is cloudy. They can also bite at any time of day.

Q. The mosquito or virus has started to mutate rapidly in recent years. Is this one reason for its spread?

A. The four dengue virus subtypes have been known for the last fifty years. A fifth dengue virus has been recently discovered in an outbreak of dengue fever in Malaysia in 2007. It has not been found in other countries and its relevance is unknown.

Q. Who are most at risk of the disease?

A. Dengue infection can develop at any age. Although 25 years ago dengue was a disease of mostly children in Sri Lanka, it now mostly affects teenagers and young adults.

Very young children, elderly people, obese patients and pregnant women are at a higher risk of developing complications. Patients with chronic diseases like diabetes and kidney disease are also at higher risk. Mothers with young children who tend to delay seeking treatment and avoid admission to hospital due to social reasons too are of increased risk having complications.

Q. What are the early symptoms?

A. Dengue virus infection is mostly asymptomatic. Hence patients will be unaware of the illness. When it is symptomatic it can manifest as one of two diseases:

Dengue Fever (DF) or the more severe Dengue Haemorrhagic Fever (DHF). It's difficult to distinguish between the two conditions during the first few days of the illness.

Patients who develop dengue for the first time generally develop DF. Patients who have had the illness previously have a high chance of developing DHF. However most patients may not recall a previous dengue episode as most primary infections are asymptomatic.

The reason for a second or a subsequent infection to be more severe is because antibodies formed after infection with a particular subtype can increase the disease severity when infected with a different dengue virus subtype.

Symptomatic dengue presents with fever which is usually of high grade. Headache, backache, joint pains and muscle pains are very common and prominent and present early.

The fever can go on for three to seven days (rarely longer) and the patients are likely to develop poor appetite, nausea and vomiting. Some can occasionally have diarrhoea on presentation which can be mistaken for gastroenteritis. Evidence of bleeding such as gum bleeding, skin patches and conjunctival bleeding are seen in some during the first few days.

Stages

Dengue fever has two stages: the Febrile (fever) stage and Convalescent stage. Patients enter the Convalescent stage as the fever recedes and show dramatic clinical improvement and regain the appetite. Their laboratory parameters also improve at the same time.

In contrast, in Dengue Haemorrhagic Fever (DHF) after the febrile stage the patients enter a period known as the critical stage. During this stage the blood vessels become porous and fluid (serum) starts to leak from the circulation into the pleura and the peritoneum (potential spaces around the lungs and the bowels respectively). They can also bleed large amounts especially into the stomach and the intestines. This may manifest as bloody or brownish vomits or tar like stools. It is during this stage that the patient's blood pressure can drop, breathing can become difficult and eventually collapse if not treated. Most patients develop some degree of liver involvement.

Q. How do you differentiate between dengue and normal viral flu?

A. Initially it may be difficult to clinically differentiate dengue from other viral infections. Headache, backache and muscle pains are commoner in DF compared to “viral flu”. Upper respiratory symptoms like sneezing and blocked nose are uncommon.

Q. Is Dengue treatable? If so, what is the treatment you initially give a patient with a suspected case of dengue?

A. Dengue is treatable and completely curable. Treatment on admission to hospital will depend on the patient's condition and the stage of the disease the patient is in. Treatment of acute dengue is supportive, using either oral or intravenous re-hydration for mild or moderate disease, and intravenous fluids and blood transfusion for more severe cases.

The most important aspect of the management is close monitoring of the patient's vital parameters (i.e. blood pressure, heart rate, respiratory rate and the urine output) along with the blood counts.

The amount and the type of fluid to be given is determined according to the above parameters, therefore it is vital that patients are admitted to a hospital before they become unstable.

It is well known that the blood platelet count drops in dengue infection. Platelets are needed for clotting blood. The dropping platelets is only one of the number of many problems that occur in dengue and it is not the main reason for bleeding.

Changes in the count is mainly used as an indicator of disease progression. Platelet transfusions are indicated only very rarely, if at all.

Q. What are the health impacts of getting dengue? What organs of the body does it affect most?

A. Dengue affects most organs in the body. It affects the blood vessels and the liver in most patients. The brain can be involved occasionally and involvement of the heart is rare. The kidneys are not directly damaged by the dengue virus. Unless the patient had organ damage due to severe and prolonged shock (due to low blood pressure), upon full recovery there will be no long term sequel due to dengue.

Q. If the fever is mild and the case is not confirmed, do you still insist the patient is admitted or allow him/her to go home and return of symptoms worsen?

A. As dengue is now endemic in Sri Lanka, any fever with body aches has the possibility of being dengue. Therefore it is important to seek medical advice early even if the fever is mild. Nevertheless all patients need not be admitted to hospital. The physician responsible for the patient will advise admission if blood counts (platelets and white blood cells) continue to drop or the patient develops any warning signs. The important warning signs are persistent vomiting, abdominal pain, faintish feeling, lethargy and bleeding manifestations. If the vomiting is preventing oral fluid intake its mandatory that these patients are admitted to hospital.

Q. Are there home remedies for such patients?

A. There are no proven home remedies for dengue. Most claims for such remedies are anecdotal or simply baseless. What is important is to make sure that patients get adequate (but not too much) hydration and has a normal urine passage. For an adult patient who is not vomiting or having diarrhoea two to three litres of fluid should be given for a period of 24 hours.

Q. What are the symptoms that indicate the disease has progressed to a more advanced stage like DHF and DSS?

A. DHF (the severe form) and DF are considered as different diseases from the outset.

Therefore DF does not progress to DHF. Dengue shock (DSS) is a later stage in DHF. DHF patients will develop the warning signs described above. If the patients goes to DSS level they will be collapsed and confused with breathing difficulties and/or overt bleeding.

Q. How does dengue affect children?

A. Children are at increased risk of getting dehydrated if they are vomiting and may not be as symptomatic as adults. It is very important that they get prompt medical attention.

Q. How can you avoid cross infection occurring within the hospital and in the same wards?

A. Cross infection is prevented by using mosquito nets in the wards during the febrile stage.  

Q. What are the hospitals specially geared to treat dengue patients?

A. The Infective Diseases Hospital (IDH) specially caters for dengue fever along with other infections. A special unit has also been established at Base Hospital, Negombo. All General and Base hospitals in the island take care of dengue patients under the supervision of specialist consultants.

Q. Are there new medical advances in 1) identifying 2) treating dengue?

A. Over past few years the use of dengue antigen test to diagnose dengue infection has dramatically increased. The NS1 antigen, the only Non-Structural protein of the virus that can be detected in blood is used as a rapid test. It is very useful in diagnosing dengue infection early.

The chances of getting a positive result is higher if done on day one of fever. However this test cannot differentiate between DF and DHF.  

Q. Are they available here? If so where?

A. The NS1 antigen test is commercially available in the private sector in Sri Lanka. It is also available in limited numbers in some major government hospitals.

Q. How long does it take for patients to obtain results of a full blood count?

A. The Teaching Hospital Colombo South at Kalubowila has automated facilities which can give full blood count result within a short period of time if urgent.

Q. Your advice to the public?

A. Dengue infection can be prevented by preventing mosquito breeding. The Aedes mosquito breeds in clear water and even a small amount of water is enough for it to breed.

The mosquito lays its eggs on the side wall of water containers and these eggs can remain viable up to a year and can start to breed when in contact with water. Therefore when emptying water containers the inside walls of these should be brushed and cleaned.

As the mosquito bites mainly during dusk and dawn use of mosquito nets at night does not offer significant protection. However wearing long sleeved dresses and long trousers as well as using safe mosquito repellents are beneficial.

The most important methods in reducing dengue infections are keeping the environment clean and taking personal protective measures.

Finally, to prevent and reduce deaths seek medical advice early from a qualified medical practitioner if there are warning signs and don't hesitate to admit him/her to a government hospital immediately.

Memories of drug addicts can be erased

Substance abusers could have their memories of drug addiction wiped in a bid to stop them using illegal narcotics, an award-winning neuroscientist has said.

According to new research by Cambridge University’s Prof Barry Everitt: disrupting the memory pathways of drug users could weaken powerful “compel” cravings, reduce “drug seeking behaviour” and open a new field of addiction therapy.

Prof Everitt, who is this year’s joint winner of the prestigious Fondation (CORR) Ipsen Neuronal Plasticity Prize, said how his research in rodents had found that targeting “memory plasticity” in rats was able to reduce the impact of maladaptive drug memories.

He added that this knowledge could offer a radical new method of treatment of drug addiction in humans, where researchers have already established that the path to addiction operates by shifting behavioural control from one area of the brain to another. This process sees drug use go from a voluntary act to a goal directed one, before finally becoming an compulsive act.

It was this process that Prof Everitt's research is trying to “prevent” by targeting “maladaptive drug-related memories” to “prevent them from triggering drug-taking and replaces”.

In humans this could potentially be done by blocking brain chemicals.

“It's the emotional intrusiveness of drug and fear memoirs that can be diminished, rather than an individual's episodic memory that they did in the past take drugs or had a traumatic experience,” said. “Conscious remembering is intact after consolidation blockade, but the emotional arousal [that] leads to drug seeking or distressing feelings of fear that are diminished.”

His research group discovered that when drug memories are reactivated by retrieval in the brain, they enter a pliable and unstable state. By putting rats in this state Prof Everitt was able to prevent memory reconsolidation by blocking brain chemicals or inactivating key genes.

In one study, the team diminished drug seeking behaviours by obstructing a brain chemical receptor linked to learning and memory, thus erasing memories, while in another study it found they could weaken drug use memories by altering a particular gene in the amygdala, a brain area processing emotional memory.

“Of course, inactivating genes in the brain is not feasible in humans,” the professor told FENS.

“So we’re directing our research to better identify the underlying brain mechanisms of memory reconsolidation.”

He added: “We specifically examined how we could target these maladaptive drug-related memories, and prevent them from triggering drug-taking and relapse.”

- The Independent

Treatment-resistant hypertension requires proper diagnosis

High blood pressure - also known as hypertension - is widespread, but treatment often fails. One in five people with hypertension does not respond to therapy. This is frequently due to inadequate diagnosis, as Franz Weber and Manfred Anlauf point out in Deutsches Ärzteblatt International.

If a patient's blood pressure is not controlled by treatment, this can be due to a number of reasons. Often it is the medication the patient is on. Some patients may be taking other medicines - in addition to their antihypertensive therapy - which increase blood pressure as a side effect. In these cases, the treatment of the high blood pressure appears to be ineffective, but all that would be needed is some adjustment to the medication regimen. Then there is diet. Licorice, for example, does increase blood pressure; so eating too much of it may reduce the effect of the antihypertensive therapy. Likewise, salt-sensitive patients may increase their blood pressure by eating salt; thus they have to keep this in mind when seasoning their dishes.

Besides drugs and food, certain symptoms may interfere with antihypertensive therapy. Once the underlying condition has been successfully treated, blood pressure control does often improve. An example for this is the sleep apnea syndrome: Apart from sleep problems and fatigue, it makes high blood pressure worse. Here, most patients find their blood pressure improved with targeted treatment of the apnea and quite often the antihypertensive medication can be reduced.

Thus rigorous diagnostic evaluation is key to a successful treatment of hypertension. In their current study the authors expect that with this approach almost half of the cases classified as treatment-resistant hypertension could be treated.

- MNT

Removing gall bladder for suspected common duct stone shows benefit

Among patients with possible common duct stones, removal of the gall bladder, compared with endoscopic assessment of the common duct followed by gall bladder removal, resulted in a shorter length of hospital stay without increased illness and fewer common duct examinations, according to a new study.

Many common duct stones eventually pass into the duodenum (a section of the small intestine just below the stomach), making preoperative common duct investigations unnecessary. Conversely, a strategy of gall bladder removal first can lead to the discovery of a retained common duct stone during surgery. It is uncertain what is the best initial strategy for treating this condition, according to background information in the article. Pouya Iranmanesh, M.D., of Geneva University Hospital and Faculty of Medicine, Geneva, Switzerland, and colleagues randomly assigned 100 patients with possible common duct stones to undergo immediate laparoscopic cholecystectomy (gall bladder removal) with intraoperative cholangiogram (an imaging technique using a dye injection to evaluate the common duct) or endoscopic common duct evaluation followed by cholecystectomy, with patient follow-up of six months.

- MNT