The Tribune, Chandigarh, India

MOSQUITOES and DENGUE
Dr G. S. Grewal

DENGUE has acquired the dubious "distinction" of being the world's most important mosquito-borne viral disease, putting about 2.5 million people in 100 countries at risk. An estimated 60 million cases occur annually, a significant fraction of which requires hospitalisation for haemorrhagic and hypotensive complications culminating in 30,000 fatalities. Epidemics of dengue fever have been reported regularly, particularly from crowded urbanised areas in tropical and sub-tropical regions, including South-East Asia (recently in India). In addition to population expansion, urbanisation, poverty, lifestyle changes and widespread travel, the changing climatic patterns have been blamed for the worldwide upsurge of outbreaks of dengue.

This fever has been recognised for several hundred years. Benjamin Rush, from Philadelphia, first described it as "Breakbone Fever" in 1780. The virus was first isolated in 1943. It is indistinguishable from the agent causing yellow fever.

Dengue fever is caused by one of the four closely related but antigenically distinct virus serotypes (DEN-1, DEN-2, DEN-3 and DEN-4) of the genus Flavivirus. Infection with one of these serotypes does not provide cross-protective immunity. Persons living in a dengue-endemic area can have four dengue infections during their lifetime The virus that causes dengue is maintained in a cycle that involves humans and Aedes aegypti, a domestic day biting mosquito that prefers to feed on man. The transmission of the virus is often seasonal, with rates increasing during hot and humid months. The vector, A. aegypti, breeds in peridomestic fresh water as might be stored in natural and artificial containers in and around human dwellings (e.g flowerpots, water storage containers etc.)

Clinical manifestations: Dengue virus infections may be asymptomatic or lead to a range of clinical presentations — even death. The incubation period is four to seven days (range: from three to fourteen). The typical dengue is an acute febrile illness characterised by frontal headache, retro-ocular pain, muscle and joint pain, nausea, vomiting and rash. The febrile and painful period of dengue lasts five to seven days, and may leave the patient feeling tired for several days. Most of the infection, especially in children under the age of 15 years, is asymptomatic or minimally symptomatic. Infants and young children may have an undifferentiated febrile disease with a maculopapular rash. Older children and adults may have either a mild febrile syndrome or the classical and even incapacitating disease. A fall in the white cell count (leukopoenia) and also a mild fall in the platelet count. (thrombocytopoenia) are frequent.

Dengue haemorrhagic fever (DHF)
DHF is defined as an acute febrile illness with minor or major bleeding. A fall in the platelet count (thrombocytopoenia) <10/ml and the evidence of plasma leakage documented by haemoconcentration, pleural or other effusions, i.e, the collection of fluid in the cavity around the lungs and other cavities, or a fall in the blood albumin levels or a fall in the protein level (hypoproteinaemia). The major pathological change that determines the severity of the disease in DHF and differentiates it from dengue is the leakage of plasma. It commonly begins with a sudden rise in the temperature and other symptoms resembling dengue. DHF usually develops around the third to the seventh day of the illness.

Dengue Shock Syndrome (DSS)
DSS is defined as DHF with signs of circulatory failure including narrow pulse pressure (<20mmHg), hypotension (fall in the Blood pressure), or Frank Shock. The four warning signs of the impending shock are intense, sustained abdominal pain, persistent vomiting, restlessness or lethargy and a sudden change from fever to a fall in the temperature (hypothermia) with sweating and prostration. The development of any of these signs or any suggestion of hypotension is an indication for hospital admission and management to prevent shock.

Other severe Dengue Syndromes
These include severe haemorrhagic, hepatic damage, heart muscle damage (cardiomyopathy) and encephalopathy. Neurological manifestations, such as altered consciousness, convulsions and coma, have been ascribed to an encephalopathy secondary to prolonged DHF/DSS, resulting from the leakage of plasma into serious spaces, haemorrhagic shock and metabolic disturbances. However, the invasion of the central nervous system (viral encephalitis) is a recently documented possibility.

Even the vertical transmission of the dengue virus has been recorded in a small number of cases, leading to neonatal DF or DSS.

Diagnosis
Laboratory findings include leukopoenia (a fall in the white cell count — TLC), a fall in the platelet count (thrombocytopoenia) and in many cases, serum aminotransferase elevations. The majority of the suspected dengue patients are most rapidly diagnosed by serology, the method of choice being lgM capture ELISA. As an adjunct technique, the amplification of viral nucleic acid by the polymerase chain reaction (PCR) facilitates the early detection of the dengue virus in the serum during viraemia which correlates with the febrile illness.

Treatment: Patients with dengue require rest, oral fluids to compensate for losses via diarrhoea or vomiting, analgesics, and antipyretics for high fever (paracetamol not aspirin) so that the platelet function will not be impaired). Steroids are not helpful in DSS. With the earliest suspicion of threatened severe illness, an intravenous line should be placed so that fluids can be provided. The monitoring of blood pressure, haematocrit, platelet count, haemorrhagic manifestations, urinary output and the level of consciousness are important. Because patients lose plasma, they must be given isotonic solutions and plasma expanders such as Ringers acetate or Ringers lactate, plasma protein fraction, and dextran 40. The vital signs should be measured every 30-60 minutes and haematocrit every two to four hours, then less frequently, as the patient's condition stabilises.

Monitoring should be continued for at least a day after defervescence. Once the patient begins to recover, extravasated fluid is rapidly reabsorbed, causing a fall in haematocrit. Before discharge, the patient should meet the following criteria: absence of fever for 24 hours (without antipyretics) and a return of appetite; improvement in the clinical picture; hospital-care for at least three days after recovery from shock; no respiratory distress from pleural effusion or ascites; stabble haematocrit; and platelet count greater than 50,000/ml.

Vaccine development
An effective vaccine will have to be tetravalent because the pre-existing heterotypic dengue antibody is a risk factor for DHF. Candidates attenuated vaccine viruses have been evaluated in phase I and phase II trials in Thailand.

Vector control
At present, dengue transmission can only be reduced by mosquito control. The effective and sustainable prevention of dengue outbreaks must include the individual community's participation in dengue control, government participation in the elimination of mosquito production sites when legal and large-scale action is necessary; and some, though limited, use of larviciddes and adulticides.

Conclusion
While awaiting the emergence of effective drugs and vaccines hopefully in the not too distant future, public education campaigns on the danger, spread and prevention of dengue should continue. Community participation and active entomological surveillance and control programmes must play a pivotal role in the battle against dengue.

Dr Grewal is a consultant physician and the Medical Director of SASGM Mediscan Hospital, Ludhiana.

Dog-fight over human rabies
Keya Acharya

Ravages of rabies

Rabies is a viral disease transmitted by saliva.
Rabies is usually spread by wild animals in industrialised countries, and by dogs in developing nations.
Every year rabies kills approx 50,000 people world wide.
Around 40,000 deaths occur in Asia, with 30,00 in India alone.
About 10m people are treated each year.
60% of the countries reported cases of human rabies in1996.
Half the world's population lives in countries where dog rabies still exists.

MORE than 30,000 people die each year in India from rabies. But the government and animal-welfare activists want to vaccinate rather than kill stray dogs. While dog-vaccination programmes are well funded, many people still receive vaccines banned by the World Health Organisation.

Bangalore: It is just past midnight on May 3. Twenty-four-year-old Venkatesh is fully conscious. His eyes are dilated with pain, chest heaving with frightening spasms. He cowers under his bed in fright.

By seven that morning he is dead in his jail-like cell at the Epidemic Diseases Hospital in Bangalore, one of India's garden cities. The young bus conductor, with a 20-year-old wife and a young baby, died of respiratory failure, another victim of the dreaded rabies.

Rabies kills at least 30,000 Indians a year, according to a 1999 World Health Organisation (WHO) report. But the WHO has warned that the death toll could be as much as 10 times higher than the figures collated from government hospitals indicate.

Rabies is a virulent viral disease, transmitted by animals through saliva. Affecting the brain, its incubation in people, especially if they are bitten, is about two months. If no treatment is received during this time, an agonisingly painful and violent death usually occurs two to five days after symptoms start to show. These include fear of water, light and draughty air.

In 1997, 500,000 dog-bites were recorded in government hospitals in India, Dr Jacob John, head of the Neuroviology Department at the Christian Medical Institution, Vellore, says in the journal Vaccine.

Dr John also points out that in the same year 700,000 people received post-exposure treatment because they had come into contact with a rabies patient or a suspected rabid dog.

"The lack of a comprehensive strategy, coupled with obstructive socio-cultural and religious myths, have resulted in the perpetuation of the rabies problem," states the WHO's Regional Strategy for Elimination of Rabies in India in its 1999 report.

The WHO advocates destroying stray dogs, but this has raised the hackles of animal rights activists who wish to control the spread of rabies by vaccinating the strays.

The Minister for Social Justice and Empowerment, Mrs Maneka Gandhi, and animal welfare groups are opposed to destroying the stray dogs responsible for spreading rabies. They advocate non-cruelty by maintaining, rather than destroying, the strays on the streets.

In 1999 Maneka Gandhi issued an ultimatum to all state health systems to conduct the government-sponsored programme called Animal Birth Control (ABC) which was officially launched in 1994 but generally unheard of until 1999.

But Dr Jayakrishna Mahendra, Assistant Professor of Community Medicine, Kempegowda Institute of Medical Sciences (KIMS) in Bangalore, feels they have the wrong focus: "Can we get our animal rights activists to understand how a human dies such an unnecessary death?"

India's 10 million or more stray dogs contribute to 96 per cent of the country's and 80 per cent of the world's incidence of rabies, according to Professor Mysore Kalappa Sudarshan, head of the Department of Community Medicine, KIMS, and also head of the Association for Prevention and Control of Rabies in India (APCRI).

Under the ABC programme, Bangalore City alone spends $258,000 a year on vaccinating and sterilising stray dogs and only $32,000 for humans says Diana Bharucha, convener of Stray Dog Free Bangalore (SDFB), a four-month old non-governmental organisation set up to educate the public on the problem of stray dogs and their link to rabies.

"Do you know of any country in the world other than India that spends more money on maintaining stray dogs than on anti-rabies vaccines (ARV) for human patients?" asks Bharucha.

"Who gives state health departments the right to sterilise these animals if right to life is the issue involved? And who gives the Health Department the right to spend THE tax-payers money on maintaining strays rather than on human health, especially of children?" asks Prof Sudarshan.

Retired Veterinary College Director (Dr) Krishnaswamy says a vaccinated dog needs re-immunisation in 11 months with the possibility of it still being a carrier.

"It is impractical to try to locate a stray for revaccination," he says.

Medical specialists also point out that while stray dogs are given modern vaccines, people are vaccinated with outdated antidotes.

"The ARVs given to strays are the modern tissue-culture ones, while our Health Department administers the outdated Semple nerve-tissue vaccine, banned by the WHO because of its inefficacy and dangerous side-effects to humans," says one rabies specialist.

(To be concluded)

HEALTH BULLETIN
Humane way to control violence

METHODS of calming and controlling violent people when their action endangers their own safety or the lives of others have been important issues facing law-enforcement institutions, airlines and other agencies in many parts of the world.

One organisation in the United Kingdom has come up with a restraint kit to provide what is a more effective and humane solution to the problem.

Called the Hugger, the product has received heightened interest, especially in the light of recent "air rage" incidents when drunk and obstructive passengers have caused disruption and threatened the safety of other air travellers.

Manufacturer TME has won a business category prize for its simple and easily applied system of restraints at the recent innovation 2000 exhibition held at Sandown Park, Surrey, southern England.

The picture shows the upper-body restraint being demonstrated at the exhibition where a variety of inventions and innovative ideas were highlighted.

The product consists of a folding composite plastic T-bar through which is threaded a strip of reinforced nylon webbing. This is tightened around the upper body by means of a ratchet mechanism on the T-bar which is held by the restrainer. Leg and wrist restraints complete the package as additional aids.

Although handcuffs are carried by cabin staff on major airlines, their disadvantage is that their use involves considerable bodily contact with the potential assailant.

The newly introduced Folding Body Restraint system keeps the person operating the device at a distance from the subject being restrained, thereby reducing body contact.

A company spokesman explained: "It allows more consideration by making it easier to care for the detainee, reducing the risk of injury and allowing the person concerned to be placed in the recovery position. It can be used to subdue someone standing or seated, who is violent or potentially violent. Police, prisons, airlines, security groups and others will find it extremely useful."

Several airlines and police organisations in the UK and the United States are reported to have expressed interest in the improved Hugger restraints which are expected to undergo trials with a view to gaining the approval of the UK's Home Office and the Association of Chief Police Officers.

(For further information contact: The UK. Tel: +44 1483 223355)

Q&A
Vital tips on Hepatitis A

(Continued from Health & Fitness of Wednesday, May 16)

Q Does hepatitis A pose a serious threat to the health of young children?

A Though hepatitis A is considered to be a relatively benign disease in young children, this may not always be the case. Children present with more atypical signs and severe gastrointestinal symptoms than adults. There is evidence to suggest that over 60% of two to five year-olds develop jaundice with associated dark urine and pale stools. The significant health risk that severe diarrhoea, nausea and vomiting can present to the young should not be forgotten.

Q Does improvement in living conditions decrease the chances of infection with hepatitis A virus?

A Yes. The risk of acquiring the hepatitis A virus is closely tied to poor standards of living. Poor standards of hygiene and sanitation favour the spread of the virus. Chances of early childhood exposure is high in this setting. In contrast, an improvement in standards of hygiene and sanitation leads to a decline in levels of circulating virus. As a result, risk of early exposure is lesser among those living in an improved socio-economic environment. In this group, contamination is more likely among young children, adolescents and adults.

Q Who is at risk?

A Any non-immune person exposed to the virus can develop hepatitis A. This includes children attending daycare centres, schools, etc. and individuals from upper socio-economic groups who are unlikely to have been exposed to the virus. Travellers to highly endemic areas, food handlers, healthcare workers, school or daycare employees and contacts of infected persons are also at risk.

Q Is hepatitis A different from hepatitis B?

A Hepatitis A and B are two different forms of viral hepatitis caused by different viruses. While the hepatitis A virus is transmitted mainly through contaminated food and water, the hepatitis B virus may be passed on through blood, sexual contact or from the infected mother to the newborn.

Jaundice i.e yellowness of the eyes, skin and urine can be an early symptom of both hepatitis A and hepatitis B.

Q Can hepatitis A be prevented?

A Immunoglobulins can be administered to provide temporary protection for three to five months. Since regular injections are required to maintain protection, this option is expensive.

A vaccine is now available and is the most practical means of protection against hepatitis A. Primary vaccination protects the person for up to one year and a booster dose administered after six months, provides predicted protection for at least 20 years.