1. Intestinal Parasites Isolated From African Refugees
at the Royal Hobart Hospital,
Richard Bradbury and Alan Thomas
Department of Microbiology and Infectious Diseases, Royal Hobart Hospital
Discussion
Migrants from foreign countries are often infected with parasites endemic to their country of origin upon entry into Australia. Of primary concern is the significant morbidity and mortality that undiagnosed and untreated infection with intestinal parasites could cause within the refugee population. Also of concern is the potential for transmission of such infections to the wider Tasmanian population and thus the potential for endemnicity to be established within the state.
A diverse variety of intestinal parasites were identified in the faecal screening of newly arrived African refugees at the RHH between 2002 and 2005 (table 2). A number of the intestinal parasites identified cannot become endemic in Tasmania due to colder climate (Hookworm, Strongyloides stercoralis), or the absence of the appropriate intermediate host required for their life cycles (Biomphalaria water snails for Schistosoma mansoni). A further number are not of Public Health significance as they are not known to cause disease (Entamoeba dispar, E. coli, E. hartmanni, Endolimax nana, Iodamoeba butschlii, Chilomastix mesnili and Trichomonas intestinalis). However, many of the parasites identified which are not currently found in this State did have the potential to become endemic within Tasmania (E. histolytica, Trichuris trichiura, Taenia spp., Hymenolepis nana) had they not been identified and appropriately treated at the refugee infectious disease clinic. Parasites recovered which are already found in the Tasmanian population (Giardia intestinalis, Blastocystis hominis, Dientamoeba fragilis) are also of concern, as had they not been identified and promptly treated in these new arrivals, the increased prevalence of infection in the population would result in a greater burden of these infections upon the health of the general population.
A small number of very unusual parasitic infections were seen over the course of this study. The rarely seen human commensal flagellate protozoan T. intestinalis was identified in one sample (figure 2). One case of Trichostrongylidiosis; infection with a nematode of the Trichostrongylid family, was identified (figure 3). Trichostrongylids known to infect humans may be carried by many mammals, infection being particularly associated with close contact with ruminants. The traditionally close contact of rural Africans with Cattle and Goats suggests acquisition from the patient’s domestic animals in Africa as the likely source. Finally, one case of gastrointestinal myiasis (infestation with fly larvae) was observed. This disease is generally transient and clinically innocuous, but may cause significant psychological distress to the patient. The larvae recovered were identified by the morphology of the posterior respiratory spiracles as being third instar larvae of Calliphora stygia (figs 4, 4a, 4b), the second most prevalent blowfly in Tasmania. This combined with the characteristically short incubation time of gastrointestinal myiasis strongly suggests that this infection was acquired in Tasmania.
Introduction
Beginning in 2002, Tasmania has become the new home for a large number of African refugees, predominantly from the Sudan and Sierra Leone, with a number of other countries of origin represented. To attend to the health needs of these refugees, a refugee infectious diseases clinic was established at the Royal Hobart Hospital (RHH) in In the three years following this, the RHH Department of Microbiology and Infectious Diseases dealt with 2686 individual faecal samples, and identified 3775 individual parasites. Many refugees presented with multiple parasitic infections.
Results
Methods
Faecal Concentration
Three separate Sodium-acetate Acetic-acid Formalin (SAF) preserved faecal samples were collected from each patient and submitted for parasitological investigation to the Microbiology Laboratory, RHH. Specimens were homogenised and 2-5 mL (depending on viscosity) of each added to separate plastic Evergreen faecal concentrate tubes. This volume was made up to 10 mL with sterile saline then tube capped and mixed. Tubes were centrifuged at 500g for 10 minutes and the excess supernatant discarded. Smears for permanent staining (table 1) were prepared by mixing one drop of the sediment with approximately ½ drop of Mayer’s albumin on a glass microscope slide. These slides were then allowed to air dry for at least 10 min.
Sediments were re-suspended in 10 mL of 10% neutral buffered formalin. Three drops of Triton X-100 (Alkylaryl Polyether Alcohol) were added and the solution mixed, followed by the addition of mL of Ethyl Acetate. The sample was then shaken and filtered according to the Evergreen method. These tubes were centrifuged again at 500g for 10 minutes. Supernatant was removed and the sediment re-suspended. Wet preparations were prepared in iodine and saline..
Permanent Staining for Protozoa and Coccidia
Prepared smears were stained using the following protocol:
Microsopy
Microscopy of the entire coverslip or slide by x100 and x400 phase contrast (wet preparations) and x1000 bright light (permanent smears) was performed using the “battlements” method.
Country of Origin of African refugees relocated to Tasmania
Unusual Parasitic Infections Identified in African Refugee Faecal Specimens
Figure 2: Trichomonas intestinalis
Figure 3: Trichostrongylid egg
Sudan
Sierra-Leone
Ethiopia
Figure 4: Larva of Calliphora stygia
(the Eastern Golden Haired Blow-fly)
Uganda
Somalia
Table 1: Modified Iron Haematoxylin with acid-fast stain protocol
Figure 1: Map of Africa showing countries of origin of African refugees entering Tasmania
Figure 4a: Anterior
Figure 4b: Posterior