Hydatid Disease (1927) by K Bremer

Cape country doctors encountered hydatid disease in maninly sheep-farming communities

As of 2012, there were 162 published reports of hydatid disease in South Africa (Wahlers et al, 2012). This is an indication that it has been a common disease in this country in recent history. The earliest paper could be one by a Dr K Bremer working in the Karoo districts of Cradock and Graaff-Reinet, who reported 8 cases in the South African Medical Journal of May 1921 (Bremer, 1921). Over the following decades there were reports of hydatid disease in numerous individual patients, affecting almost every organ. These reports continue today (Andronikou et al, 2002; Ndondo et al, 2003).

Surprisingly, there has never been an epidemiological survey to put a figure on how common human infection actually is in South Africa, even though there have been veterinary surveys in wild and domestic animals. During one such survey in domestic dogs around Pretoria back in 1934, Dr Reinhold Ortlepp distinguished South African veterinary parasitologist, identified a couple of new species of echinococcus (Ortlepp, 1934). Today his work is recognized in the species name E. ortleppi. The WHO considers cystic echinococcosis (hydatid disease) to be endemic in contemporary South Africa (Eckert et al, 2002).

Historic photomicrograph of hydatid scolex head, magnifieed 200x

Informational Cartoon by the Agricultural Research Council of South Africa

The Biology of Hydatid Disease

The adult worm resides in the gut of canids (wild and domestic dogs, jackals, foxes) while the larvae develop in the tissues of ungulates (hoofed animals). In Southern Africa the parasite tends to cycle between domestic dogs and sheep, and so is mainly encountered in sheep-farming areas of the country.

The eggs of the worm are shed in the faeces of dogs and this is where humans enter the frame. Infection is most often acquired in childhood, quaintly explained so:

"In childhood the fingers travel readily and often to the mouth, without the intermediate blessing of soap and water"

(Latham, 1953)

Eggs gain access to human digestive tract, where they hatch, and the embryo then burrows through the gut into a vein, and so gets access to any part of the body via the circulation. Most (80%) come to rest in the liver, about 10% in the lung, and the remainder in just about any other site. There a cyst is formed and slowly grows, with proto-tapeworms developing within it. The cyst is generally only detected when it becomes large enough to cause symptoms, and then is best carefully removed through surgery. Complications can be fatal.