REFERRING to The Star’s various reports recently on the dengue outbreak, let me say that an epidemic is said to exist when the incidence (number of new cases within a certain period) of the disease exceeds the usual incidence of that same period. Hence, “spikes” are epidemics when significantly sustained. From the statistics provided by the Health Ministry through news reports over the past weeks, it appears there is a dengue epidemic throughout the country (at least in most states).
While community health education, inspection and enforcement are important aspects of dengue control, early detection, prompt notification (through a Health Ministry phone hotline), prompt isolation of dengue cases, and prompt fogging (to kill adult mosquitoes) of the affected area (homes and working places), are more important.
It is also true that only complicated cases require hospital care, but even milder cases require isolation. It is crucial to prevent a non-infective mosquito from biting a dengue case and then becoming infective to go on to bite a healthy human. Such efforts would reduce the size of the dengue reservoir in the area of concern. This strategy is particularly viable with the recent availability of the NS1 Rapid (instant) Antigen blood test, which only requires three drops of blood, and is positive on the first day.
Fogging of areas where dengue cases arise is only effective if it is done promptly. Any delay would have caused a spread of the disease already. Fortunately, asymptomatic (non-clinical) infections of the disease do not occur.
It is a public health principle that all cases of an infectious disease with high morbidity, high mortality and high transmission rate must be isolated to prevent spread of the disease. Isolation, in the case of dengue, should be for five days, which is the period of communicability of the disease.
If isolation of cases is a constraint because of the limited availability of ward space in hospitals, then the milder cases must be issued with citronella (natural) mosquito repellent patches to be worn day and night, although patient-compliance is a risk here. This should be acceptable to most patients because the patches only need to be stuck on one’s clothes.
The Health Ministry must sell these mosquito repellent (whole-day protection) patches at its clinics at subsidised prices and also provide adequate publicity to inform the general population about them. Everybody should be able to afford these patches, which now retail at RM15 for 10 in pharmacies.
In the recent past, SARS, H1N1, and Ebola were controlled mostly by isolation of cases. Malaria did not require isolation because there was a specific treatment for it. There is no specific treatment for dengue.
Some time ago, cases of leprosy required isolation in leper colonies mainly because of high morbidity, although mortality and transmission rate of the disease is very low. Isolation brought leprosy under control in Malaysia.
The blood platelet count is usually done as part of the full blood count (FBC) which costs around RM50 at GP clinics, and not RM100 to RM158 as reported in the news. The FBC also includes a haematocrit (HCT) measurement and a haemoglobin (HB) measurement.
Doctors should realise that an increase in HCT and HB is also strongly indicative of dengue in a patient with acute fever, as is a fall in the platelet count, although they are not as confirmatory as the NS1 Antigen test and the IgG and IgM tests. Also, FBC changes may not occur until the third day, delaying the diagnosis, notification and isolation of case.
Increase in HCT and HB is due to concentration of red blood cells in the blood vessels because the disease causes plasma-leakage out of the blood vessels.
All patients presenting with fever must have the NS1 test done.
The Health Ministry should subsidise the cost of doing the test so that it would be no more than between RM30 and RM50 at clinics and hospitals nationwide, unlike the present RM100 to RM200.
If this is a financial constraint, then the test must be done on all those presenting with fever accompanied by headache, body ache, joint pains, eye pain and rashes, and patients with diarrhoea, vomiting and abdominal pain preceded by fever.
Even small children know that dengue could cause death. Yet, efforts at reducing the Aedes population over the past decades have been futile.
The Aedes mosquitoes, Aedes egypti (which breeds indoors) and Aedes albopictus (which breeds outdoors), are instinctive in their breeding.
They require no more than small amounts of clean, clear water for a week to breed.Littering and delayed garbage collection, while disgusting, do not allow Aedes to breed unless the discarded glass, plastic and polystyrene containers collect water.
Even releasing GM mosquitoes and other forms of sterile male mosquitoes in the dengue hot spots may not succeed because of logistics constraints.
The Aedes’ flight is limited to an 800m radius, meaning that such male mosquitoes must be released at every 1.6km diameter of human habitation.
The Health Ministry must approve the Dengvax vaccine and make it adequately available quickly in view of the present epidemic. It does not matter if it is not effective against Serotype 2 of the dengue virus: three out of four is not bad.
The ministry, the Vector-borne Disease Control Division, state health departments and local council health departments must also be innovative in their approach towards dengue control/eradication.
RETIRED PUBLIC HEALTH CONSULTANT