The government and local bodies, which could not control mosquitoes or supply mosquito nets to the poor, will again embark on mass administration of drugs for filariasis later this month, assuming that an unknown percentage of the population is infected. (Official documents claims that the prevalence of microfilaria towards the end of last century was about 15 per cent. Current figures are not known.)
This is somewhat like administering paracetamol to the entire population during monsoon assuming that many people have contacted fever. No one knows whether repeated administration of drugs (diethyl carbamazene citrate-DEC and albendazole) year after year would reduce its effectiveness. Filaria may develop resistance over a long period, going by the evolutionary principle. WHO had conducted a study in 2008 to find out whether the effectiveness of albendazole had decreased following mass administration among children in Nepal. (Though the study has been reported on the WHO Website, the results could not be found.)
However, the main concern is regarding the ethics and use of funds. It is against medical ethics to administer potent drugs to people with no disease for which the drug is a cure. Moreover, principles like that a doctor should see the patient and administer drugs as per body weight is dispensed with. This also means that advisable precautions are not taken. (See http://www.icm.tn.gov.in/drug%20formulary/ANTIINFECTIVE%20DRUGS.htm)
Drugs for entire families are delivered together by volunteers even to children if the parents are not at home. There is the risk of children consuming the drug indiscriminately, resulting in overdose. Warning against use of the drug by infants, pregnant women and the elderly may not always reach them. Both DEC and albendazole are prescription drugs which are to be administered by doctors and supplied through pharmacists.
The mechanism of action of the diethylcarbamazene citrate against microfilaria (the causative parasitic organism of filariasis) is not known. Latest studies show that the unusual and novel therapeutic effect on the cell walls of the parasite which is yet to be fully studied. The drug has effect on human neutrophil and eosinophil. (See http://www.ncbi.nlm.nih.gov/pmc/articles/PMC185347/pdf/aac00198-0157.pdf)
Doctors are not even sure of the dosage (The earlier recommendation was for administration of diethyl carbamazene citrate for 12 days. Now the prescription is just one dose of the drug combination). Still, it is being administrated to the entire population (excluding three districts in Kerala) though none can be sure of long term effects of taking the drug year after year. Albendazole can cause birth defects in newborns, if taken during pregnancy, according to authoritative sources. (See http://www.nlm.nih.gov/medlineplus/druginfo/meds/a610019.html)
Reaction to diethyl carbamazene citrate can range from dizziness, nausea and vomiting to skin rashes, fever and even anaphylaxis (which can be fatal). The latter reactions caused by dead microfilaria rather than the drug occur only if microfilaria is present in the body in large numbers and anaphylaxis will occur only in people allergic to dead microfilaria. ( A case of such reaction was reported from Trivandrum Medical College years ago.) Few reports of such incidents in Kerala indicate the prevalence of microfilaria is actually lower than projected.
The practice of mass drug administration against filariasis had been started about a decade ago. The claim was that the disease could be eliminated in five years with 65 per cent coverage of the endemic areas. This did not happen and the project is now being extended with new target of 2015 for elimination. If the money spent on mass drug administration was spent on improving primary health care, it could have helped in the treatment of many diseases.
The prevalence of filariasis, it may be noted, is actually the results of lack primary health care. Diseases like elephantiasis, the advanced form of filariasis, occur in society because of absence of proper health care. For filariasis could be cured, if detected at its early stages, and progression into elephantiasis could surely be prevented. Doctors can easily advice tests to confirm filariasis at early stage when swelling of testis or breasts is noticed.
Elephantiasis is absent among upper strata of society because they get early treatment. Incidence of filarisis is also lower among them because of use of mosquito nets and other measures to prevent mosquito bites. If the government provided mosquito nets to the poor, instead of drugs for cure, not only filariasis but also other vector borne diseases such malaria, Dengue fever, chikungunya could have be prevented to a great extent.