Dengue control is in your hands

By Carol Aloysius

Dengue is rapidly reaching epidemic levels with the number of suspected cases mounting each day. To control its spread, the Health Ministry has launched a special Dengue Control program next week with hundreds of health officials and Public Health Inspectors visiting houses in an attempt to minimise the number of breeding sites which have largely contributed to the spread of dengue.

Chief Medical Officer Dehiwela - Mt Lavinia Dr Indika Ellawala discusses how dengue spreads, its symptoms and most importantly how one can prevent its complications leading to death.

Excerpts…

Q: What is dengue?

A: It is an infection caused by a virus. The virus is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. There are 4 subtypes of the virus: DEN 1, DEN 2, DEN 3, DEN4. Therefore a human can contract Dengue fever four times during the life time.

Q: What is a dengue mosquito?

A: It’s a very active small black mosquito. The female Aedes mosquito is the vector of dengue. It bites several people to get one blood meal. It bites mainly during the mornings and evenings.

Q: What is the life span of this mosquito?

A: The life span of an adult Aedes mosquito is around 2-4 weeks. During that period it lays eggs around four times – with 100- 200 eggs at a time. The eggs are sticky and thus difficult to remove.

Q: How long does it take for an adult mosquito to lay its eggs?

A: Around 7-11 days.

Q: For how long can these eggs remain live?

A: Eggs can remain live up to one year in dry conditions and hatch on contact with water

Q: Who are the groups most vulnerable to getting dengue?

A: The risk groups are as follows:

1. Children: Because the Aedes mosquitoes are day bitters, school going children are more vulnerable to get infected with dengue virus.

2. Elders, since their immune system has weakened.
3. Obese people
4. Persons with chronic diseases (e.g. Bronchial asthma, diabetes)
5. Persons with immunodeficiency.

Q: What are the symptoms that indicate a person is infected with the dengue virus?

A: Around 90 percent of people infected with the dengue virus for the first time do not show symptoms and signs. But they too have dengue virus in their blood for 5-7 days.

During this period if they are bitten by mosquitoes, the virus can enter into these mosquitoes with the blood meal and multiply within the mosquitoes.

These infected mosquitoes can then transmit the virus to healthy people. So you may have already contracted dengue fever for the first time with or without your knowledge.

Q: Once the virus enters the body, how long does it take for symptoms to present?

A: Between 7-10 days to develop symptoms and signs.

If a person is infected with one subtype of dengue virus, antibodies are formed against that subtype and he/she will be protected for that particular virus subtype in the future, but not protected for remaining three subtypes.

Therefore they can contract dengue fever again by any of other three subtypes of virus.

When a person contracts dengue fever for the 2nd, 3rd, or 4th time, the disease is more severe than first episode, and the possibility of developing Dengue Haemorrhagic Fever (DHF) is high.

Q: You mentioned DHF. Are there other types of dengue as well?

A: Many patients infected with dengue virus remain asymptomatic. Others can develop a febrile illness one of the following types:

·Undifferentiated fever

·Dengue Fever (DF)
·Dengue Haemorrhagic Fever (DHF) - most serious

Q: How does dengue progress to its most severe form (DHF)?

A: It goes through the following phases:

1. Fever phase
2.Critical (Leakage) phase
3. Convalescent

(Recovery) phase

Fever phase

Fever phase usually lasts 2-7 days.’ During fever phase the patient can have body aches and pain, muscle pain ,severe headache, pain behind the eyes, vomiting and rash (Red Colour). Sometimes there can be sore throat and congestion of eyes (red eyes).

These symptoms are similar in both dengue fever and dengue haemorrhagic fever.

Sometimes the fever can subside abruptly, but the patient’s condition deteriorates and goes into complications of dengue fever.

Therefore monitoring of patient’s general condition, adequate rest and fluid intake will be helpful to prevent complications.

Critical phase

The critical phase is usually evident after three days of fever and the symptoms and signs are due to plasma (liquid part of the blood) leakage through blood vessels due to the adverse effects of the virus on walls of blood vessels. This will cause thickening of blood and circulatory failure leading to shock. Due to the same reason, there is reduction of blood supply to essential organs in the body causing failure of vital organs.

Patient can die of either of these complications or by both.

Q: How can you prevent a patient going into this critical phase?

A: Early detection and prompt treatments can prevent death. Reduction of platelets is usually not a reason for death in dengue patients.

Convalescent (Recovery) phase

During recovery phase, plasma which leaked out of the blood vessels will re-enter the blood stream and patient’s condition improves gradually.

Regaining appetite and improvement of urine output are some indicators of recovery. During this phase too it is necessary to take adequate rest and food.

Q: What are the early suspected symptoms of dengue?

A: Watch out for the presence of the following clinical features with acute onset of fever.

Headache and retro-orbital pain.

Joint pain (Arthralgia) and muscle pain (myalgia)

Rash

Laboratory findings

· Low white cell counts (Leucopenia - WBC 5000/mm3)
· Low platelet count (?150,000/ mm3)
· Rising Haematocrit (HCT- 5-10 percent)

Q: Can dengue be managed at home?

A: It can be managed at home by adhering to the following guidelines:

Carers must ensure the patient gets adequate oral fluid intake (oral rehydration fluid, king coconut water, other fruit juices, kanji, soup).

Avoid red and brown drinks

* Adequate physical rest
* Tepid sponging for fever
* Paracetamol (10-15mg/kg/dose - Do not exceed 60mg/kg/24 hours)
* Anti-emetics if necessary.
* Avoid other analgesics in any form and steroids.

* Review daily with Full Blood Count (FBC)

* First FBC should be done on the third day of fever and daily thereafter if the platelet count is 150,000/mm3; twice daily if 150,000/mm3).

However, a FBC is recommended on the first day of fever during infancy and in patients with major medical problems

Warning signs

·Inability to tolerate oral fluids
·Refuse to eat or drink
·Feeling extremely thirsty
·Severe abdominal pain/ vomiting
·Cold and clammy extremities
·Bleeding manifestations

·Not passing urine for more than six hours
·Behavioural changes: Confusion, restlessness, lethargy, irritability

Criteria for admission

·All patients with a platelet count of ?100,000/ mm3
·All patients with above mentioned warning signs

Infants, obese patients, patients with major medical problems, patients with adverse social circumstances (living alone, living far from health care facility without reliable transport, unreliable patients also should be admitted.

b) Hospital

Mortality from dengue can be reduced by timely management. Appropriate clinical management, which involves early clinical and laboratory diagnosis, intravenous rehydration and staff training.

Q: Can dengue be prevented with vaccines?

A: A vaccine against dengue fever is in the process of being developed.

Q: As the Chief Medical Officer of two high risk areas what steps are you taking to control the spread of dengue in those areas?

A: We use chemical control. This can be effective in controlling the mosquito population.

Insecticides can be used to kill mosquito larvae or adult mosquitoes.

The use of insecticides is recommended in emergency situations during dengue epidemics.

On a regular basis use of chemical methods can make mosquitoes to develop resistance to insecticides.

In addition, insecticides are expensive and harmful to humans when using high doses. Mosquito repellents which contain DEET, Picaridin or oil of lemon/eucalyptus.

We also advise residents to take the following precautions:

·Avoid being bitten by mosquitoes

-Keep unscreened windows closed

One practical and recommended environmental management strategy is to eliminate unnecessary breeding habitats that collect water (plastic jars, bottles, cans, tyres) in which Aedes aegypti mosquito can lay the eggs. This strategy is called ‘source reduction’.

Q: Some people prefer to rely on traditional medicines offered by native physicians to cure dengue. Your comments?

A: Many native physicians promise overnight cure for dengue.

But there is no scientific basis for these medicines. These medications can worsen the scenario.

My advice is to get treatment and advice from a qualified medical practitioner who will handle each case according to the latest National Guidelines for Dengue management.

Q: Your message to the public?

A: Action at community level is an effective method of reducing mosquito breeding sites. But for communities to understand the need to make behavioural changes, they should be educated about mosquito vectors and the risk of having mosquito breeding habitats near their houses.

As all of us are at risk in dengue virus infection, please pay attention to roof gutters because 20 percent of breeding places are found in those sites.

Comments

We have noticed that in more than 75 percent dengue cases, the source of infection is inside their premises and people still believe that this source reduction exercise has to be carried out by health officials. People have to realise that regular cleaning of their premises is their own responsibility.

To some extent the law enforcement also has helped reduce the dengue cases.

Air pollution linked to autism and schizophrenia

A new study has revealed that exposure to air pollution damages the brain of developing mice, affecting the same area of the brain that is known to play a role in autism and schizophrenia in humans.

Researchers from the University of Rochester in the US found that when mice were regularly exposed to fine particle pollution in the first two weeks of their life, they developed a range of brain abnormalities which are consistent with patterns seen in humans suffering from schizophrenia and autism.

These harmful effects were mainly observed in the male mice; a finding that corresponds to the fact that boys and men are more likely to be diagnosed with both of these disorders.

“Our findings add to the growing body of evidence that air pollution may play a role in autism, as well as in other neuro-developmental disorders,” said Deborah Cory-Slechta, professor of Environmental Medicine at the University of Rochester and lead author of the study, published in the journal Environmental Health Perspectives.

Exposure to fine particle air pollution was found to cause inflammation in the brains of the young mice, damaging the development of white matter. The lateral ventricles, cavities in the brain which are filled with cerebrospinal fluid and protect the brain from trauma, were found to be enlarged to up to three times their normal size, filling up the free space in the underdeveloped brains.

This dilation of the ventricles has previously been linked to autism and schizophrenia in humans. In addition, after breathing the contaminated air, the male mice exhibited a high level of glutamate in the brain, a neurotransmitter found to be abnormally high in individuals suffering from these same two conditions.

The air pollution created in the lab by Cory-Slechta and her colleagues matches the level typically present during rush hour in a medium-sized US city. The mice were exposed to the impure air for four hours a day during four days of their first week of life, followed by a further four days during the second week after birth. Developmentally, these timings correspond to the period just before and just after birth in human babies.

The study focused on the ultra-fine particles in polluted air, believed by the researchers to be more detrimental to health than their larger counterparts, which can be filtered out by the nose and lungs. Although most previous research on the adverse health effects of pollution has focused on the consequences for the respiratory system and heart function, earlier studies have linked airborne pollutants to other neuro-developmental problems, including cognitive decline and depression.

The new findings correspond with a recent study by researchers at the University of Southern California and the University of California, in which children who spent their first year of life in areas with high levels of air pollution were found to be three times as likely to develop autism than those starting out in cleaner surroundings.

Currently, an estimated one percent of people in the UK could be affected by a disorder on the autistic spectrum.

The prevalence of autism is growing, and researchers are keen to understand the reasons behind what some describe as an “autism epidemic”. Earlier this month a report emerged linking the condition to higher levels of testosterone in the womb.

Schizophrenia affects a similar number of people, and, like autism, its causes are far from being fully understood.

According to Cory-Slechta, her discovery does not necessarily mean that pollution is responsible for causing autism or schizophreniA: “I never use the word ‘causes,'” she told USA Today.

“I try to make people understand it's the interaction of all these risk factors in your life, over your lifespan, that come together.”

However, she does believe that changes in regulation should be considered: “I think these findings are going to raise new questions about whether the current regulatory standards for air quality are sufficient to protect our children”.

-The Independent