Sustaining dengue and chikungunya prevention programmes in 2007

Role of the citizens, NGO, government and private sectors:

Dr. Pradeep KARIYAWASAM

A MAJOR CHALLENGE: Dengue Fever (DF) and Dengue Hemorrhagic Fever (DHF) are acute febrile diseases, found in the tropics, with a geographical spread similar to malaria.

Caused by one of four closely related virus serotypes of the genus Flavivirus, family Flaviviridae, each serotype is sufficiently different that there is no cross-protection and epidemics caused by multiple serotypes (hyperendemicity) can occur.

Dengue is transmitted to humans by the mosquito Aedes aegypti (rarely Aedes albopictus). The term ‘dengue’ is a Spanish attempt at the Swahili phrase “ki denga pepo”, meaning “cramp-like seizure caused by an evil spirit”.

A global pandemic began in Southeast Asia in the 1950s and by 1975 DHF had become a leading cause of death among children in many countries in that region.

Epidemic dengue has become more common since the 1980s - by the late 1990s, dengue was the most important mosquito-borne disease affecting humans after malaria, there being around 40 million cases of dengue fever and several hundred thousand cases of dengue hemorrhagic fever each year.

A clinical dengue fever-like illness has been known to be endemic in Sri Lanka from the beginning of the century, and it was serologically confirmed in 1962.

Following an outbreak of chikungunya in 1965, there was an islandwide epidemic of dengue associated with DEN type 1 and 2, with 51 cases of DHF and 15 deaths, from 1965 to 1968.

Although most of the towns throughout the country were affected during this outbreak, the greatest impact was felt in the western coastal belt. Colombo, the capital, recorded the highest number of cases and the first two cases of DHF was also occurred at this time.

In Colombo, cases of dengue fever have demonstrated a biphasic pattern over the past with two separate peaks, the first occurring around June - August and the second around November - December, following the monsoon rains.

It is clearly evident that Dengue fever is associated with the rainfall and shows an increase following the monsoon rains.

Chikungunya

Chikungunya fever is a viral disease transmitted to humans by the bite of infected mosquitoes, usually Aedes Aegyptii or Aedes Albopictus but many other mosquitoes may be involved with suspected mutation of the virus.

Chikungunya virus (CHIKV) is a member of the genus Alphavirus, in the family Togaviridae.

CHIKV was first isolated from the blood of a febrile patient in Tanzania in 1953, and has since been identified repeatedly in west, central and southern Africa and many areas of Asia, and has been cited as the cause of numerous human epidemics in those areas.

Epidemics of illnesses resembling chikungunya have first been recorded from India as early as 1824. However after isolation of the virus (CHIKV) in 1953 the disease has been reported from a wide geographic region from West Africa to Philippines in Asia.

It has been reported from Sri Lanka in 1969. Most recent outbreaks have been reported from India (Kerala and Tamilnadu) and various Indian Ocean islands including Comoros, Mauritius, Reunion and Seychelles.

The term ‘chikungunya’ comes from Makonde, the language of the ethnic group Makonde in the South Eastern part of Tanzania and Northern Mozambique. This word refers to the meaning ‘that which bends up’ with regard to the crippling nature of the illness.

CHIKV infection can cause an acute debilitating illness, most often characterised by fever, severe joint pain and rash.

It is characterised by a rapid transition from a state of good health to the illness. Temperature rises abruptly as high as 40 degree C (typically in children) and is often accompanied with shaking chills.

After a few days fever may subside and rise again resulting in a saddle back fever curve. Arthralgia or joint pain is Polyarticular and symmetrical involving knees, elbows, ankles, and small joint sites of previous injuries. Pain is most intense on waking up in the morning.

Chikungunya patients typically avoid movements as much as possible. Joints may swell without significant fluid accumulation. These symptoms may last from 1 week to several months and are accompanied by myalgia or muscle pain.

Rash characteristically appears on the first day of illness, but onset may be delayed. It usually arises as a flush over the face and neck, which evolves to a maculopapular or macular form with pruritis.

It later spread to the trunk, limbs, palms and soles in that order of frequency. Petechial skin lesions can also be seen.

Other symptoms may include headache, photophobia, fatigue, nausea and vomiting. Hemorrhagic phenomena are relatively uncommon.

The prolonged joint pain associated with CHIKV is not typical of dengue. Co-circulation of dengue fever in many areas may mean that chikungunya fever cases are sometimes clinically misdiagnosed as dengue infections, therefore the incidence of chikungunya fever could be much higher than what has been previously reported.

Sri Lanka experienced an epidemic of Chikungunya in 2006, spreading from Mannar and the Eastern Province to the other parts of the country.

Due to the availability of a non-immune population the disease spread to epidemic proportions in the latter part of 2006 involving even citizens of Colombo.

In all the islands or towns where chikungunya spread between 50 to 80 percent of the local population were affected.

Hence, as the economic centre of the country the magnitude of the problem is critical for the Sri Lankan economy’s survival as Colombo would come to a standstill in case of a large outbreak!

Therefore, for the control and prevention of these two diseases that devastated Colombo in 2006, the Public Health Department of the Colombo Municipal Council has initiated a control programme termed “No to D and C campaign” which has activities spread throughout the year.

The “No to D and C campaign” was initiated by the Public Health Department of the Colombo Municipal Council as a joint Public Private partnership towards a better tomorrow. Several leading governmental and non-governmental institutions have teamed up with us in this endeavour.

The strategies undertaken by the Colombo Municipal Council, Public Health Department in controlling and preventing these two diseases are as follows:

* Strengthen the existing surveillance system - We had initiated this surveillance system where our staff visited the hospitals in the Colombo area on a daily basis and collected the information on the reported dengue cases.

* Geographic mapping to identify the high-risk areas - Case information was mapped geographically, including information from past years to identify the potential high-risk areas.

* Rapid vector control (prevention of clustering) - on receiving the case information, a team comprising of a Public Health Inspector, A field Assistant and members of the vector control unit would visit that place and conduct mosquito control activities in an area of 250 metre radius from the housing unit. Rapid action of this nature has prevented clustering of cases during this year to a considerable level when comparing to the previous years.

* Routine integrated vector control programmes

* “No to D and C campaign” - Special House to House inspection programme - March 31, 2007

* 1,000 volunteers, 12500 houses inspected in high risked areas - Dengue and chikungunya - walk

* 1,000 volunteers and school children

* Around the Municipal Council - School based dengue control programme

* School awareness programme

* Setting up of dengue control teams within the schools

* Buffer zone creation around the schools - 250 metre radius

* Activities for a sustainable behavioral change in the students

* School recycling programme - Government institution based control programme

* Awareness programme

* Shramadana campaigns

* Routine inspections and monitoring

* Prosecutions - Housing scheme based control programme

* Awareness campaign

* Recycling programme

* Shramadana campaigns

* Chemical control

* Prosecutions - Transitional settlement based control programne

* Awareness campaign

* Shramadana campaigns

* Routine inspections

* Empowering the community for mosquito control

* Chemical control

* Mapping of Bare Lands and Construction sites and routine inspection and mosquito control work in and around them

* Strengthen the prosecutions - From May 1, 2007, the charge levied for harbouring and breeding mosquitoes will be Rs. 25,000.

* Supervision, monitoring and evaluations

It is now evident that dengue cannot be controlled without the fullest cooperation of the general public.

In Colombo, we have come to identify that approximately 95 per cent of the cases are within 250 metres from a bare land, 90 per cent of the cases are within 250 metres from a construction site, 85 per cent within 250 metres from a governmental or private institution, 65 per cent within 250 metres from a school and 60 per cent within 250 metres from a garbage collection depot or a disposal site.

These are the approximate findings of the environmental research conducted by the Public Health Department of the Colombo Municipality.

It is also evident that although the people keep their immediate surroundings clean, bare lands, construction sites, governmental and private institutions and schools with all sorts of breeding sites favourable for mosquito breeding are within a distance of 250 metres from their dwellings.

Having a multitude of such high-risk environments, which are known dengue-breeding sites clearly indicate hot spots for outbreaks.

The Public Health Department of the CMC has done well compared to other areas to keep the number of patients to a minimum, even though our staff strength is at an all time low. Just seven years ago Colombo accounted for about 15-30 per cent of the dengue patients found in the country.

Last year our share was less than 7 per cent and although the country had a 110 per cent increase Colombo with its sustained efforts reduced the increase to 9 per cent in the city. This year by mid April the country had 1,574 patients; Colombo District 446, with 74 in the city.

Therefore, it is up to the public of the Colombo city area to help us to sustain these low levels and keep the city of Colombo free of dengue breeding sites by eliminating them.

It is important to remember that dengue mosquito has a maximum flying range of 250 metres (average 50-150 metres), and although you keep your surrounding free of breeding, if your environment is not clean you are at risk of contacting Dengue fever.

Apart from the schools, other governmental institutions, private sector conglomerates should use this strategy to safeguard the health of their workers by sustaining such a programme in the future.

The message from the Public Health Department is to keep your house and garden free of mosquito breeding and keep your surrounding environment, at least around a radius of 250 metres, free of breeding with the help of your neighbours to prevent a dengue epidemic taking place in Colombo this year and in the future.

Remember, breeding dengue mosquitoes is a punishable offence. Don’t practise it and don’t let others practise it. It is your responsibility to safeguard your own and fellow citizens’ health.

The writer is the Chief Medical Officer of Health, Colombo.