Current Status of Human Hookworm Infections, Ascariasis, Trichuriasis, Schistosomiasis Mekongi and Other Trematodiases in Lao People's Democratic Republic

Abstract

Abstract. Soil-transmitted helminth (STH) infections, and schistosomiasis and other trematodiases often have a high prevalence in developing countries. Here, we present updated information on the prevalence of these parasites in the Lao People's Democratic Republic (Lao PDR) in 2012, arising from the annual national helminthiasis survey. Fecal specimens were collected from 8,610 inhabitants of 12 provinces and one municipality (Bokeo, Houaphan, Luang Namtha, Luang Prabang, Oudomxay, and Phongsaly Provinces from northern Lao PDR; Bolikhamxay and Xieng Khouang Provinces and Vientiane Municipality from the central part of the country; and Attapeu, Champasak, Saravan, and Sekong Provinces from southern Lao PDR). The overall prevalence of three major STHs, Ascaris lumbricoides, Trichuris trichiura, and hookworms (Necator americanus and Ancylostoma duodenale) were 11.6%, 8.5%, and 25.0%, respectively. Prevalence of Schistosoma mekongi infection was 0.1%, and of miscellaneous trematodiases (including opisthorchiasis) was 14.0%. Clearly, the nationwide parasite control project is still necessary to reduce morbidity caused by helminthic diseases.Three major soil-transmitted helminths (STHs), i.e., roundworms (Ascaris lumbricoides), whipworms (Trichuris trichiura), and hookworms (Necator americanus and Ancylostoma duodenale) are important public health problems, mostly impacting the health of children in several countries of the Americas, sub-Saharan Africa, China, and East and Southeast Asia, including Lao People's Democratic Republic (Lao PDR). 1-3 Ascaris lumbricoides is estimated to infect 1.221 billion people globally, T. trichiura 795 million, and hookworms, 740 million globally. 1 The blood fluke, Schistosoma mekongi, occurs in communities along the Mekong River in Cambodia and Lao PDR, 4 causing intestinal and hepatosplenic disease. 5,6 Many other trematode species can also infect people in Lao PDR. These include the highly pathogenic liver fluke, Opisthorchis viverrini, heterophyids such as Haplorchis taichui, and lecithodendriids such as Phaneropsolus bonnei, and Prosthodendrium molenkampi. 7 To help planning for improvement of control strategies and evaluation of existing control activities, there was a need to update information on the prevalence and distributions of STHs and schistosomiasis and other trematodes. The information is presented here.During parasitological surveys in 2012, fecal specimens were collected from 8,610 inhabitants located in 12 provinces and one municipality (Figure 1). Sample size calculation was performed by using simple random sampling based on estimated preliminary prevalence data for STHs (Laymanivong and others, unpublished data). A total of 58 villages from 29 districts were randomly selected (2 or 3 districts per province and 2-3 villages per district). Approximately 300 inhabitants, with equal sex ratio, were randomly selected per village. The study was approved by the Ministry of Public Health, Lao PDR. Oral informed consent was obtained from all human adult participants and...

Intestinal Helminths Recovered from Humans in Xieng Khouang Province, Lao PDR with a Particular Note on <i>Haplorchis pumilio</i> Infection

“…The average prevalence was 32.7% (210/643) and the worm load was fairly high (average 21.5 worms per infected person). This prevalence was similar to that (37.7%) in our previous study [ 1 ] and that (39.5%) in another study in Xieng Khouang Province [ 22 ]. However, the rate was somewhat higher than the average nationwide figure (19.1-27.8%) in Lao PDR [ 1 , 23 ].…”

Prevalence of Intestinal Parasites and Associated Risk Factors for Infection among Rural Communities of Chachoengsao Province, Thailand

“…In our study, the most common intestinal soil-transmitted helminths found were hookworms with a prevalence rate of 6.7%, similar to results reported by the national survey of helminthiasis in Thailand where a prevalence rate of 6.5% was found [ 4 ] but lower than previously reported in Thailand (ranging from 8.0% to 14.5%) [ 10 , 14 , 15 ], Myanmar (8.7%) [ 16 ], Malaysia (11.8%) [ 17 ], Lao People’s Democratic Republic (Lao PDR) (25.0%) [ 18 ] and Cambodia (ranging from 9.6 to 57.4%) [ 19 , 20 ]. The second most dominant parasite was S. stercoralis with a prevalence rate of 5.0%, which concurred with a previous study by an author who determined the infection rate to be 5.5% among gardeners in Chanthaburi Province [ 8 ], Eastern Thailand.…”

Repeated stool sampling and use of multiple techniques enhance the sensitivity of helminth diagnosis: A cross-sectional survey in southern Lao People's Democratic Republic

“…Haplorchis taichui, Haplorchis yogokawai, Haplorchis pumilio, Phaneropsolus bonnei and Prosthodendrium molenkampi) are endemic in the lowlands of the Mekong River basin (Chai et al, 2005(Chai et al, , 2007Eom et al, 2014;Sayasone et al, 2009). The blood fluke Schistosoma mekongi is endemic in the lower Mekong River, in the most southern part of the country (Laymanivong et al, 2014;Muth et al, 2010;Sayasone et al, 2011;Urbani et al, 2002).…”

“…With regard to soil-transmitted helminths, Ascaris lumbricoides and Trichuris trichiura are highly prevalent in the mountainous and highland areas of the country, particularly in the north, while hookworm is highly prevalent across the country (Ayé Soukhathammavong et al, 2012;Laymanivong et al, 2014;Rim et al, 2003;Sayasone et al, 2011). The liver fluke Opisthorchis viverrini and five species of small intestinal trematodes (i.e.…”