ReviewHuman Oesophagostomiasis: A Serious Public Health Problem in Tropical Africa

Abstract

A review was made on what was known of the history, geographical distribution, diagnosis, public health significance, pathology, epidemiology and control of human oesophagostomiasis, as well as the taxonomy, morphology and life cycle of its causative agents, with the following being the highlights. Historical events were described from its first record in Ethiopia in 1905. Notable among these include, a long period of only a few isolated cases and then mostly in association with immature worms which resulted in regarding man as an abnormal host; the subsequent proof of complete life cycle in man and demonstration of endemicity in Togo and Ghana on clinical, coprocultural, and sonographical grounds; the role of monkey as source of human infection, elucidation of progression of clinical disease; and high efficacy of alberndazole for clinical and mass treatments. Taxonomy of the causative agents adopted by majority of authors into various taxa, from kingdom to species level, was given, noting slight differences especially in the family. Geographical distribution was comprehensively described as covering many areas in Africa but also included few areas in Asia and one location in South America. Information on morphology of aetiological agents focused mainly on features of diagnostic value mostly in the cephalic region, and bursa copulatrix and spicules in males of adults, tails and sheath in infective larvae, and number of cells in eggs in fresh stool. The life cycle of the causative agents was described in details including all the pre-parasitic stages, histotropic phase with some progressing to adults in lumen and some failing to reach maturity and remain in cysts. Full pathology was given, the initiation of which is the migration of juvenile stages into sub-mucosa. Accounts on epidemiology provided information on patterns of distribution and relation of transmission to seasons and role of monkeys and of man in the propagation of infection in Togo and Ghana. Diagnosis by various means was provided including clinical signs; presence of palpable and often painful mass in the abdomen; use of coproculture, laparatomy serology, PCR based method, ultrasound; radiology; and histopathology. The public health and socioeconomic significance was described including details of clinical conditions produced, incapacitation and occasional deaths. Control measures available were given which included chemotherapeutic treatment and public health enlightenment on how to recognise infection for appropriate management and for prevention.

Keywords: Human oesophagostomiasis, endemicity, albemdazole, histotropic, phase

Nigerian Journal of Parasitology, Vol. 32 [2] September 2011, pp. 325-340