N. Janat Ali, S. Miozuddin, J. Qureshi, R. Paul, S. Luby

Department of Community Health Sciences, Aga Khan University

Rabies not only kills Karachites every year, but attempts to prevent it consume precious medical resources. The current system of vaccinating persons bitten by a dog with sheep brain vaccine is not 100% effective because not all persons bitten by a rabid dog seek vaccination, and the vaccine as currently manufactured and administered in Pakistan is not universally effective.

We compared the cost effectiveness of the current vaccination strategy with a proposed program of widespread dog elimination in Karachi. Using studies conducted in the CHS department in December 1994 we assumed the incidence of rabies in Karachi to be 9.0 cases per 1 million persons the incidence of dog-bites to be 52 per 100,000 persons, and the proportion of persons with dog-bites who would receive any vaccine, complete, or incomplete vaccination as 77%, 53% and 24% respectively. We estimated the cost of complete medical therapy (including facility overheads) for a dog-bite including the 17 injection vaccination series to be Rs. 1,000. We further assumed there were 625,000 dogs based on published dog to person ratios in the region, and we estimated the cost of eliminating dogs to be Rs. 50 per dog based on interviews and record review of Karachi Municipal Co-operation (KMC).

Under the current system there are 90 deaths from rabies among Karachiites per year, 61 deaths occurring in patients who received some vaccination. If we assume 50% vaccine efficacy this means for every 61 deaths there are 61 lives saved, and over 10 years 610 lives saved. The cost for vaccinating the 77% dog-bite victims who present to hospitals is Rs. 40 million for 10 years or Rs 655,737 per life saved. Of the 151 individuals (90 + 61 saved by vaccination) bitten by rabid dogs each year, we anticipate that, with aggressive dog control, 90% would not be bitten and so their deaths would be avoided. Therefore in 10 years, 1359 persons will be saved. The cost for the dog control would vary over the 10 years. During the initial two years we anticipate to spend Rs. 31,250,000 and Rs. 15,625,000 to eliminate 625,000 and 312,500 dogs respectively. With this intensive phase we expect to reduce the dog population to 10% of its current size and therefore over the next 8 years spend Rs. 3,125,000 maintaining it at or less than this population size. Therefore the total spent over 10 years is Rs. 71,875,000 or Rs. 52,888 per life saved.

In conclusion aggressive dog control would cost more money in its initial years, but would save substantially more lives. Dog control is an order of magnitude more cost effective than the current system.

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