Case Scenario 05

Adopting effective surveillance and control templates for anthrax

Anthrax is a very good model for assessing control programmes in many parts of the world because (a) it is fairly common or common in many countries, and (b) it is relatively easy to diagnose. So if it is being missed when present, it is likely that other diseases circulating in the same area, which are harder to diagnose, are also being missed.

In Europe and North America, which acquire anthrax through contaminated imports from enzootic countries, there has been a reduction to near nil of contaminated imports. This, at least in part, reflects the reduction of the disease in the exporting countries through vaccination and other improved control programmes. However, it is clear that we do not know a lot about the incidence of the disease in enzootic areas. A glance at the figures given on the OIE website shows the relatively small numbers being reported and the very sporadic nature of reports from the enzootic countries. Interviews with district level veterinary staff in various countries of sub-Saharan Africa confirm that anthrax is an ongoing problem, but this is not apparent from available figures. Comparing the latest available (2004) data with those of five years earlier, little change is apparent in figures of countries other than Ethiopia, Guinea and Zimbabwe. Of those countries reporting at all, half are reporting just bovine cases. This matters because humans can contract anthrax equally well from sheep, goats and other domestic species.

What evidence is there that there is under-reporting as inferred above? Two contrasting situations can be cited, in this instance. In Turkey, human cases are shown as exceeding animal cases in 2001 to 2003. The explanation given is that often more than one person contracted the disease from a single animal. This becomes believable if both public health and veterinary services are reporting efficiently. In contrast, in a survey undertaken in a district of Tanzania in 1999, a substantial number of human cases were found to have been recorded in the health clinics but not a single case in the corresponding veterinary clinics. In this case humans are the sentinels of animal cases and the evidence of under-reporting is clear.