Danger Dengue ahead

By Hiranthi Fernando

• How to prevent Dengue

With the onset of monsoon rains every year, the Dengue virus begins to spread alarmingly. Not only in Sri Lanka, but in other tropical countries as well, Dengue Fever is one of the most rapidly expanding diseases, with over two billion people at risk of infection and millions of cases occurring every year. For the first five months of this year, 453 suspected cases of Dengue Fever have been reported in Sri Lanka, of which 62 have been confirmed positive and three deaths have occurred.

“Although Dengue has not reached epidemic proportions so far this year, because of the expected increase in density of the vector mosquitoes with the rains, we have to take precautions,” Dr. Ms. Hapugoda, Director of the Health Education Bureau said. The peak incidence of the disease is found to occur usually in June/July with the Southwest monsoon or later in the year during the Northeast monsoon.

A presidential task force was appointed two years ago, to strengthen community based activities for the prevention and control of Dengue. “The Minister met the Presidential Task Force on Dengue last week and declared a Dengue Control Week from 22nd June to 29th June,”Dr. Hapugoda said. “During this week, many activities will be undertaken by mobilising the public, school children, non- governmental organizations and local government authorities. A campaign to eliminate Dengue breeding places is being planned. Special emphasis is given to a schools based approach. Dengue awareness programmes will be conducted in schools. School children will be used as communicators and change agents. Children will go out in groups to distribute pamphlets, identify and point out the mosquito breeding places in their neighbourhood so that these could be cleaned up.

Dr. Tissa Vitarana, a former Director of the Medical Research Institute, now an advisor to the Ministry of Science and Technology, is a member of the presidential task force on Dengue. Dr. Vitarana explained that Dengue is transmitted by two species of mosquito the Aedes Aegypti and Aedes Albopictus.

These mosquitoes are daytime biters and so the anti mosquito measures taken at night such as coils and nets give no protection. They are active within a range of four kilometers from their breeding sites.

There are four types of dengue viruses. Infection and recovery from one type of virus does not protect a person from another type. The antibodies that are built up give protection from that particular type only. In the event of infection by another type of dengue virus however, these act as enhancing antibodies which helps the second infection to spread and develop more rapidly. The second and third infection therefore tend to be more severe. Repeated infection by different types of dengue has been found to lead to the severe forms Dengue Haemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS). These severe forms of dengue have been found to affect mostly young children.

Dr. Maxie Fernandopulle, Paediatrician at the Lady Ridgeway Children’s Hospital who is also on the Dengue Task Force, explained the clinical diagnosis and treatment of Dengue. Dengue Fever is generally a benign disease characterised by fever, headache, rashes and severe body aches and so is known as a break- bone fever. For every 200 patients who get dengue fever, there will be one who develops Dengue Haemorrhagic Fever. One third of the DHF cases may progress to Dengue Shock Syndrome unless they are diagnosed early and properly treated.

Dengue infection weakens the walls of the blood vessels resulting in plasma leakage. The virus also suppresses the production of platelets which helps in the clotting of blood. If the process continues unchecked, the volume of blood reduces due to leakage and the blood pressure drops. Along with it, the platelet count reduces. Bleeding occurs and the patient goes into serious shock syndrome. This is more common in children than in adults.

“The seriousness of dengue is related to the extent of antibody production,” Dr. Fernandopulle said. “Dengue thus affects healthy well nourished children because they produce more antibodies”.

Dr. Fernandopulle said that the infection has just begun to appear this year, and has not reached alarming proportions as yet. In his ward at the Lady Ridgeway Hospital he has treated just one case. The earliest manifestations of Dengue Fever is a flu like disease accompanied by body aches.

Non specific symptoms like stomach pains and vomiting may occur. A useful feature in differentiating it from a normal flu is that it is not common to have a cough or cold with it. An observant mother may notice the face and neck appearing more rosy, especially in a fair skinned child. This flushing may also appear on the palms and soles. Closer evaluation may reveal red spots on the skin, which continues usually for three to four days. Fortunately, in the majority of cases, the fever abates, the symptoms disappear and the child recovers.

It is essential that the child is made to rest and kept away from school, Dr. Fernandopulle stressed. He or she should be given plenty of fluids, preferably colourless drinks.

Soft solids and easily digestible foods may be given. However, the child should not be forced to eat unnecessary food and cause vomiting. Being a virus infection, antibiotics are not of any use. Drugs like Paracetamol should be used to bring the temperature down. It is important to ensure that the recommended dosage is administered and not more than 3-4 times a day. If the temperature does not come down, the environment needs to be kept cool and the child dressed in minimum clothing, kept cool and comfortable. Sponging with tepid water is advisable.

“The most dangerous period is the leakage phase which usually takes place around the 4th or 5th day,” Dr. Fernandopulle said.

“The child develops abdominal pains with significant vomiting. The colour change in the vomit to red or black or brown is ominous since it indicates bleeding in the stomach.” This is why it is best to avoid giving coloured drinks as it makes it difficult to detect bleeding. Further, he said more red spots may develop on the skin and the stools would also be black in colour. Bleeding can take place from various areas such as intestines, nose, skin, lips or gums. These symptoms indicate DHF and at the earliest signs of it, the child should be admitted to a children’s ward. The blood needs to be closely monitored and appropriate treatment given to prevent the patient going into the highly dangerous DSS. “The deaths are due to the situation not being checked and the patients going into shock syndrome. At that stage, treatment is very difficult,” Dr. Fernandopulle said.

The treatment of the DHF stage on the other hand is not difficult in the care of a well experienced doctor, he further explained. The correct quantity and type of intra-venous fluid should be administered, frequently monitored by simple blood tests. Fortunately, the leakage phase lasts only 2 - 3 days. If well cared for, the child will make a total recovery without any sequel. “Demanding blood tests in the early stages of the disease may not be helpful in management or outcome,” he said.

“To establish exact diagnosis, seriological tests are available, some accurate and some less so. It is not possible from a single blood test, to say definitely that the child has Dengue Fever. Blood tests at appropriate times will help the doctor to monitor your child and prevent the disease progressing to more serious stages.”

“In Sri Lanka, up to 1988, though we had definite evidence of three types of dengue virus and possibly a fourth, we had no severe dengue,” Dr. Vitarana said. “In 1989, we had 203 cases of severe dengue, with 20 deaths. In the following year it rose to over 1000. Each year between 1991 and 1995, between 400 to 1000 clinically suspected cases have been reported with approximately 4% deaths occurring. The figures rose further in 1996 to 1294 suspected cases and 54 deaths.”

Statistics also show that the highest number of cases are reported from Colombo and the suburbs. Of the 453 cases reported this year, 240 are from Colombo. It is also found that the highest percentage of DHF and resultant deaths occurred in the age group 5-9 years, followed by children under five years.

Dr. Vitarana says that since the total volume of blood in a child is less, the reduction in volume due to plasma leakage has a quicker impact on children. Thus they are more susceptible to serious forms of Dengue. He cautioned that if a child’s fever goes down suddenly around the fifth day, one still has to watch out for signs of shock such as paleness of body, cold, clammy skin, and rapid pulse rate, since the fever can go down due to shock.

According to Dr. Vitarana, research is still going on in the identification of viruses and changes they may have undergone. In a particular type of virus there are strain differences. There may be strains that are prone to produce more severe forms of the disease than others. “Probably, some severe strains have come in from other countries and established themselves in Sri Lanka,” Dr. Vitarana said. “In Thailand for instance, taking three separate years in the last decade, over 100,000 dengue cases have been admitted to hospitals. In any average year, Thailand has 40,000 cases. Twenty five years ago however, Thailand had figures like ours. It seems to be a feature in South East Asia that with the passage of time the problem gets worse. Unless we do something about it now, the situation will worsen.”

“We ourselves are responsible for our childrenís deaths from dengue,” Dr. Vitarana said. “The mosquito breeding occurs mainly in containers we provide, such as tins, bottles, coconut shells, plastic containers, tyres, water storage containers, flower vases, ant traps and gutters. Wherever rain water collects and is left for over a week, the mosquito can breed. Studies at the Medical Research Institute show that 90% of the mosquitoes in the country breed in containers scattered around in the open which collect rain water. If we make a habit of ensuring that water is not collected around our own dwellings, we can prevent mosquitoes from breeding.”

Further, he said the Dengue mosquitoes cannot breed in dirty water or in large collections. To develop from larvae to the adult stage it takes more than a week. We therefore have to inculcate in our population the practice of looking around their premises one day a week to ensure that rain water is not collected in discarded containers. Dr. Vitarana recalled an instance when seven children from a leading school in Colombo were seriously ill with dengue. The Task Force sent the municipal health personnel to inspect the school premises. They found plenty of mosquito breeding places in this school. “I consider such a school a failure despite the high rate of Advanced Level passes they may have,” Dr. Vitarana commented. “They have not protected their children.”

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