Transmission While it is a parasite infecting mostly primates, rodents and other mammals, Bertiella is transmitted to humans by the accidental consumption of oribatid mites, which are the intermediate hosts. These mites are important components of soil fauna, and are widely distributed. In the rare cases that dogs and humans have contracted an infection, it is attributed to proximity and frequency of soil contact in certain regions. More than 50 cases of Bertiella have been cited, with a high frequency of those being children. The disease is reportedly endemic to 29 countries. In documented cases in Mauritius, the infection was traced back to the consumption of guavas which had been picked up from the ground. Reservoir Non-human primates, rodents, Australian marsupials. Morphology Like all Cyclophyllidea, Bertiella has a scolex, suckers, and many segments called proglottids. These are released into the body from the adult tapeworm, contain both male and female anatomical structures, and are in stages of mature, postmature and gravid. In general, human Bertiella morphology is not well understood due to the rarity of infection, and therefore limited possibility for study and observation. Particularly lacking are descriptions of adult stages of the species. Most common are studies of proglottids passed in stool samples of infected hosts. Studies have shown that specimens collected from humans are essentially morphologically the same as specimens collected from monkey hosts, except for some anatomical differences in reproductive organs. However, these discrepancies in morphological findings have led researchers to postulate that there may be more than two human Bertiella species, as previously believed. These gravid proglottids in stool are white and can measure around 11 mm for maximum length and 8 mm for maximum width. Full tapeworm observations in the past have included a worm that was 130 mm long, 15 mm in width, and 2.5 mm in thickness. It had a scolex, neck, and 418 proglottids. Differences in human species: B. mucronata has smaller eggs than B. studeri. There are filaments arising from the pyriform apparatus clearly identifiable on B. studeri but not B. mucronata. Life cycle There is relatively little known about the life cycle of Bertiella, but inferences and assumptions can be made about it through observations of specific parts of the worm, and knowledge of other cases in the same family (Anoplocephalidae). Anoplocephalids are heteroxenous parasites and require both an intermediate and definitive host to complete their cycle. For Bertiella, nonhuman primates are generally the definitive host, and oribatid mites are the intermediate host. Human infection occurs when a person inadvertently consumes an oribatid mite infected with Bertiella larvae. Within the human (the definitive host) the larvae migrate through the gastrointestinal tract, using their morphology to stick onto parts of the intestines. From there, the adult tapeworms can live for at least two years, feeding off the host and producing/shedding eggs and proglottids. The eggs and prgoglottids are passed in stool, and the eggs are taken up by oribatid mites (the intermediate host) in the soil. In the mites, Bertiella develops into the infective cysticeroid and begin producing larvae. The mites are then consumed by humans again, or by the nonhuman primate or rodent reservoir.
Bertielliasis
Mansonelliasis
Isosporiasis
Paragonimiasis
Scarabiasis
Metagonimiasis
Naegleriasis
Dracunculiasis