Prevalence of Soil-transmitted Helminthiasis in Central Eastern Division, Fiji Islands
Soil-transmitted Helminthiasis (STH) affects approximately 1.5 billion people annually, 450 million of whom become ill as a result of infection. The World Health Organisation has labelled STH as a major neglected tropical disease (NTD). STH infections are caused by roundworm (Ascaris lumbricoides), whipworm (Trichuris trichiura), hookworms (Ancylostoma duodenale and Necator americanus) and threadworm (Strongyloides stercoralis) which are transmitted to humans by ingestion of infective eggs or contact with larvae. Fiji has inadequate data on the health status of STH. Insensitive laboratory diagnostic techniques suggest limitation exists in positive detection and cases maybe under-reported. There is no published data on STH infection and its association with NTDs, which limits information on trends relating to morbidity and efficacy of helminth control programmes.
The purpose of this research was to determine if the reference diagnostic laboratory at Colonial War Memorial Hospital (CWMH) in Suva, Fiji was using a sensitive and accurate STH examination technique. The major objectives of the research were to: (1) determine the prevalence of the soil-transmitted helminths diagnosed at CWMH in Central Eastern Division from January 2008 to December 2016 according to data retrieved from the laboratory register; (2) identify the current laboratory techniques used in diagnosing STH in Fiji and compare these with current recommended methods; and (3) provide recommendations to medical laboratories and the Fiji Ministry of Health to improve STH diagnosis.
Results from data analysis showed that from the total of 12,020 stool sample results retrieved 2.2% (n=261; 95% CI: 1.4-2.9) were positive for at least one STH parasite. A. lumbricoides contributed to most STH infections (68.7%), followed by hookworm (22.2%), S. stercoralis (8.0%) and T. trichiura (1.1%). The highest prevalence of STH was found in the < 5 year age group (33%). More samples from male patients had STH positive results (61%) compared to females at 101/261 (39%). In regards to ethnic groups, a higher proportion of i-Taukei population had helminth infections (93%) compared to Indo-Fijians (6%) and other races (1%). According to gender distribution, male i-Taukei individuals are mostly infected (48.4%), followed by female i-Taukei (33.5%), the Indo-Fijian females (4.7%) and Indo-Fijian males (2.2%), while other races were the least infected (0.4%). Fiji still depends on direct microscopy and is lacking behind in STH diagnosis according to the updated WHO helminth testing standards. For STH diagnosis, the Kato-Katz (K-K) technique has been recommended by WHO as the gold-standard. The qPCR technique is an emerging molecular diagnostic technology and is considered superior to the K-K technique, due to its increased sensitivity and specificity. However, the higher costs involved in processing samples and the need for specialist technical staff could affect its implementation.
The prevalence study provides important epidemiological data of the STH parasites in the Central Eastern Division in Fiji. Socioeconomic factors, improper hygiene practices, climate change, rural-urban migration and remoteness could contribute towards STH infections. The K-K technique has been recommended by the WHO as the -gold-standard- for STH diagnosis in medical laboratories and should be implemented to diagnose STH in Central Eastern Division in Fiji. For future potential investigations of helminth infections, sustainable evaluation of parasite characteristics should be investigated for effectiveness of control factors.