A 24 year old woman presented at the gynaecology outpatients department of a hospital in Zimbabwe, complaining of lower abdominal pain and infertility of about 8 years duration. She was diagnosed as having a low grade pelvic infection and treated with antibiotics. Her condition improved but she was admitted to hospital for investigation of an 8cm pelvic tumour. A full blood count indicated that she had a significant eosinophilia. A laparotomy was performed and a 10 cm ovarian cyst was revealed together with a small nodule. The nodule was removed and sent for histology (Fig. 2.1). The parasite found in the nodule was dissected out of the remaining tissue (Fig.2.2).
The woman was infected with the pentastomid, Armillifer armillatus. This is a mite-like parasite the adult of which (Fig. 2.3) lives in the lung of a snake.
Fig 2.3 - Adult Armillifer armillatus taken from snake lung
Eggs pass out with the snake’s nasal secretions and contaminate vegetation. Contaminated plant material is then eaten by the intermediate hosts, which are rodents. When the rodent is eaten by a snake, the life cycle is completed. Humans become infected (a condition known as porocephaliasis / pentastomiasis) when they intrude on the normal cycle (Fig. 2.4).
Fig 2.4 Life cycle of Armillifer armillatus
Thus humans may ingest eggs on plants or may become infected when they eat snake meat. High prevalences (45.4%) have been reported in snake-eating communities such as some forest dwelling aboriginal tribes in Malaysia (Prathap, Lau and Bolton, 1969).
Diagnosis is made, as in this case by biopsy or on X-ray where the parasite larvae in the tissues appear as concentric-shaped shadows(fig 2.5).
Fig 2.5 - X-ray showing larvae of Armillifer armillatus
In this case the woman could have become infected by accident through ingestion of eggs on plants. African tribes do not as a rule use snake meat as food, but the woman may have been treated by a N’anga. These traditional healers sometimes use snake meat as “muti” (medicines) – thus Gelfand (1964) in a study on the medical practices of African healers (particularly in Zimbabwe), mentions that “mangoromera” is a medication which includes, amongst other ingredients, shato (snake). It’s function in this medicine is to instil courage which although unlikely in this case, does show that snakes may be used medicinally.
Gelfand, M (1964) Medicine and Custom in Africa. London and Edinburgh. Livingstone.
Goldsmid, J.M. and Melmed, M.H. (1973) A brief review of human porocephaliasis with a report of the first case of human infection with Armillifer sp. in Rhodesia. C.Afr.J.Med. 19: 213-216.
Prathap, K., Lau, K.S. and Bolton, J.M. (1969) Pentastomiasis: a common finding at autopsy among Malaysian aborigines. Amer.J.Trop.Med.Hyg. 18:20-27.