War against dengue

Timely decision by the Health Ministry to prioritize dengue control:

Dr Punsiri Fernando

From historical times, vector-borne diseases, most of them mosquito-borne, affecting the population of Sri Lanka were not unknown. Foremost among them was Malaria transmitted mainly by the mosquito Anopheles culicifacies, which ravaged the dry zone of the island, leading to its depopulation, until spraying of the then wonder insecticide Dichloro Diethyl Trichlorethane (DDT) spraying to the houses commenced in 1946, after initial trials in Anuradhapura district.

Sri Lanka (then Ceylon) was the first country in whole of Asia to commence DDT spraying covering the entire malarious area of the country. Since then the country no longer suffered the regular periodic Malaria epidemics which were witnessed during the pre-DDT era, nevertheless, the post-DDT era too witnessed several epidemics during which the deaths caused by Malaria illness were minimal, if not negligible.

Dengue mosquito breeding place. File photo

Operational defects, unprecedented drought conditions, and ecological changes following large developmental schemes and the conflict situation which prevailed for decades in the Northern and Eastern Provinces were responsible for these epidemics.

With the advent of new generation residual insecticides (eg; synthetic pyrethroid) and new drugs to combat drug-resistant species of malaria found in certain parts of the island, a well-trained and motivated set of Regional Malaria Officers, serving in all malarious districts, under the guidance of the then anti-malaria campaign technical staff, were successful in controlling malaria transmission to very low levels and to minimize deaths from malaria. Compared to the nearly 400,000 confirmed Malaria cases detected during the year 1991, the year 2005 recorded only around 1,500 confirmed cases, in spite of the limited access the Malaria campaign officers and field-workers had to several districts in the Northern and Eastern Provinces.

Anti-malaria campaign

The decentralization of the activities of the anti-malaria campaign, which took place in March/April, 1989, in accordance with the then policy of devolution of power to the Provincial Councils, greatly facilitated the efficiency of the Malaria control program.

The assistance received from the World Health Organization and the Global Fund to fight AIDS, TB and Malaria (GFATM) deserves very special mention.

Lymphatic Filariasis, another mosquito-borne disease too was prevalent from historical times. Although not a killer disease, much debility due to deformities was common in the olden days, due to patients not taking early treatment. Fortunately, following new treatment regimens administered, the disease is quite under control.

The dreadful disease of plague, a bacterial disease transmitted by a flea (Xenopsylla cheopis) which gets infected by biting a plaque-infected rat, was prevalent in Sri Lanka until the ‘40s, but has been eliminated due to the stringent measures taken by the Health Department.

Japanese encephalitis, a viral disease transmitted mainly by the mosquito Culex tritaeniorhynchus which picks up the virus from an infected pig, caused a serious problem during 1987, when an epidemic was experienced in Anuradhapura district, with a mortality rate of nearly 30 percent. Districts of Polonnaruwa, Puttalam and Kurunegala were also affected. Due to prompt action taken by Health Department by introducing the vaccination campaign against Japanese encephalitis, in several districts, nowadays only isolated cases or groups of cases are encountered.

It is quite obvious that an unprecedented epidemic of dengue fever, almost islandwide, accompanied by a high incidence of dengue haemorrhagic fever and dengue shock syndrome, associated with an unacceptably high death rate is sweeping across the country.

Viral infection

The viral infection is self-contained and usually disappears after about five days, in uncomplicated cases, but much pandemonium has resulted from the unacceptably high death rate, particularly taking the lives of blossoming children, due to the complications of dengue haemorrhagic fever and dengue shock syndrome.

The Health Department has done a lot by greatly improving the facilities available to the affected patients, such as early confirmatory diagnostic facilities, early prediction and detection of complications through investigations, availability of blood platelet transfusions and preparations to combat plasma loss. However, in spite of medical interventions the complications are often stubborn enough to cause death.

Need of the moment

The wisdom of immediate establishment of a combined vector-borne diseases campaign key for controlling Dengue is to prevent transmission, particularly prevention of vector breeding. Why successful control seems possible?

Ready availability of mosquito-borne disease control units: A countrywide organization for the control of mosquito-borne disease Malaria has been existence in malaria-endemic districts, for the last several decades. Traditionally non malaria-endemic districts like Colombo, Kalutara, Galle, have established organizations to control the mosquito-borne disease lymphatic filariasis.

The Regional Officers in-charge of the districts are either Medical Officers who have been trained in vector-control work, or Scientific Officers (many of them having the post-graduate qualification of PhD, and wide experience in research and vector-control work).

The staff of these Regional offices also include experienced Public Health Inspectors, Entomological Assistants, Public Health Laboratory Technicians, Public Health Field Officers, and Spray Machine Operators, all of whom are quite competent in their duties. Availability of transport facilities, which usually poses a big constraint in regard to public health field programs, has been overcome to a very large extent subsequent to the provision of vehicles for fieldwork, by the Government under various foreign funded projects.

Reorganization required

In view of the inevitable formalities associated with the establishment of a new department to control dengue, which would result in a substantial delay that could be a big drawback at a time when an epidemic of dengue associated with a high death rate is ravaging the country, it is my considered opinion that the immediate establishment of a vector-borne diseases control unit in the Ministry, incorporating the personnel and resources of the anti malaria campaign and the anti filariasis campaign, supported by the Epidemiology Bureau, Entomology and Virology Departments of the Medical Research Institute, will pay much dividens.

The above department, under the able and technically sound guidance of its chief Dr Pradeep Kariyawasam has performed a yeoman service within the Colombo Municipal limits in which very often the prevalence of dengue illness was highest.

I am of the strongest opinion that the proposed V. B. D. C. Unit of the Health Department should necessarily include Chief M.O.H, Colombo Municipal Council as a member and utilize his expertise.

Functions of the proposed VBDC

Dengue: To take action to combat the present epidemic, instituting vector control activities required during epidemics (including making recommendations to enact and enforce necessary legislative action to prevent man-made breeding sites), and thereafter to maintain vector control activities in such a manner that dengue would no longer be a public health problem in Sri Lanka in the future.

Japanese Encephalitis

The main thrust is by means of the vaccination campaign carried out by the epidemiology bureau of the ministry of health. However vector surveillance in sentinel stations (specially in areas where large-scale pig breeding is practised) has been quite useful to prevent focal outbreaks, in our past practice.

Malaria

The present objective of the national Malaria program being elimination of Malaria from Sri Lanka, the efforts should be to have a quite strong fool-proof surveillance system covering the island, to prevent any importation of Malaria to the country, and to prevent any new Malaria FOCI, as well as having emergency units to combat any FOCI/Outbreaks as they occur.

Any new ecological changes following developmental schemes. (eg: Moragahakanda Dam and the water distribution system)

These should be closely monitored to ensure that no increased potential for Malaria vector breeding is created.

Lymphatic Filariasis

Resulting from new strategies such as Mass Drug Administration carried out in affected districts, the microfilaria rate has been brought down to a very low level by the Anti Filariasis Campaign, Elimination of lymphatic filariasis from Sri Lanka seems near at hand.

The writer is a former consultant in Control of Vector-Borne Diseases and former Health Ministry Anti-Malaria Campaign Director