Date Published: April 05, 2018
Publisher: The American Society of Tropical Medicine and Hygiene
Author(s): Sung Hye Kim, Milika Rinamalo, Meleresita Rainima-Qaniuci, Nemani Talemaitoga, Mike Kama, Eric Rafai, John H. Lowry, Min-Ho Choi, Sung-Tae Hong, Jaco J. Verweij, Louise Kelly-Hope, J. Russell Stothard.
As part of lymphatic filariasis (LF) transmission assessment surveys (TAS) on Fiji, an island-wide assessment of gastrointestinal protozoan infection was performed by inspection of a concomitant stool sample collection to investigate the distribution of parasitic protozoa. All grade 1 and 2 students of 69 schools on the two main islands were targeted in two phases (one in the Western Division and the other in the Central and Northern Divisions, except Taveuni sub-Division of Northern), where fecal samples of 1,800 students were available for coproscopy using formalin-ether-acetate concentration. The overall prevalence of Giardia infection was 1.6%, having 2.2% in Western and 0.8% in Central/Northern Divisions (P = 0.094). The school-level prevalence of giardiasis ranged from 0% to 15.4%, and hotspot analysis using the Getis-Ord Gi* method detected spatial heterogeneity of giardiasis prevalence in schools around Lautoka (Z-score = 3.36, P value < 0.05), an area affected by Cyclone Kofi in February 2014. Any protozoan infection prevalence was 4.9% in Western and 4.4% in Central/Northern Divisions (P = 0.825). Real-time polymerase chain reaction analysis to confirm the findings from a parasitological examination of a 10% stool archive in 95% ethanol from Western Division revealed an elevated prevalence of giardiasis up to 22.4%, the presence of Entamoeba histolytica, and the absence of Cryptosporidium parvum. Obtaining stool samples alongside LF TAS is a convenient access platform for cosurveillance of gastrointestinal protozoan infection and has pinpointed hitherto unknown hotspots of giardiasis in urban city centers of Fiji. This calls for greater attention to apply tailored water, sanitation and hygiene measures for the control of these parasites.
Oceania is a region of tropical and subtropical islands in the Pacific Ocean where one-quarter of the population is living in poverty, which places them at an increased risk of several neglected tropical diseases.1 Among others, lymphatic filariasis (LF) and soil-transmitted helminthiasis (STH) are particularly widespread.2 However, regarding gastrointestinal protozoan infection, such as giardiasis, their epidemiology is not well known,1,3 outside Australia,4,5 New Caledonia,6 New Zealand,7,8 and Papua New Guinea,9 even if the infection is associated not only with acute and self-limiting illnesses but also chronic diseases such as persistent diarrhea and malabsorption.10,11
In total, 932 students in 30 schools from Western and 958 in 39 schools from Central/Northern Divisions, except one special school for the disabled in Central, participated in the suvey, with the overall response rate of 68.3%. Altogether 915 samples were available for microscopic examination using the FEC in Western Division, whereas 995 in Central/Northern Divisions (Table 1). The age range of the participants was between 4 and 10 years, and 92.6% were either 6 or 7 years old. More male students (52.2%) were enrolled than female students (47.2%) (Table 1). The overall proportion of students being stunted, wasted, and underweight was all lower than 5% (4.7%, 4.7%, and 3.2%, respectively). The distribution of males and females, location of schools between urban and rural, source of water supply, or latrine type at schools was not significantly different between Western and Central/Northern schools, but there were a greater number of students aged 4 or 5 years, stunted, wasted, and underweight in Western schools than in Central/Northern schools with statistical significance (Table 1).
Having a better appraisal of gastrointestinal protozoan infection is important but continues to be problematic owing to present diagnostic difficulties in both operational and reference diagnostic settings.23 Previously, on Fiji, only a few studies have been performed, but with limited focus on gastrointestinal protozoan infection, and were undertaken long ago during 1960–1980s with variable results.15 In 1968, a survey conducted in a rural village reported Giardia lamblia, with prevalence levels of 5.4%,16 whereas another survey near Sigatoka Valley in 1982 reported Giardia infection among children younger than 15 years, with prevalence levels of 1–5%.24
By adding the FEC and real-time PCR to the LF TAS survey, we were able to shed new light on the distribution of gastrointestinal protozoan infection including Giardia spp. across the island. Using TAS as an access platform for surveillance of protozoan infection was convenient, and the introduction of other diagnostic techniques such as DNA-based methods using archived stool samples should be more actively pursued. Spatial analysis using the Getis-Ord Gi* method highlighted that schools with a high prevalence of Giardia infection were clustered around in the urban areas of the Western Division, possibly because of contaminated water or foods after the floods caused by Cyclone Kofi. Enhanced surveillance efforts should be considered in the disaster-affected areas to explore whether there is possible contamination of water sources or any increased level of the endemicity of Giardia infection.