Occurrence of and risk factors for Strongyloides stercoralis infection in South-East Asia

The soil-transmitted nematode, Strongyloides stercoralis is one of the most-neglected of all neglected tropical diseases. It is globally distributed, favouring the humid, wet climates of the tropics and subtropics. Inadequate sanitary conditions promote the spread of S. stercoralis infection. In South-East Asia, many countries provide the ideal ecological and economic setting for high S. stercoralis infection rates. Yet, in most of these countries, little is known about the actual prevalence and distribution of S. stercoralis. One reason for this lack of knowledge pertains to the time- and resource-intensive diagnostic methods used to detect S. stercoralis infection. The Koga Agar culture method and the Baermann method are considered to be the best coprological diagnostic methods for field settings today. Both detect the parasite with high sensitivity. This sensitivity can be increased further by examining stool samples for several consecutive days, thereby increasing the chances of detecting low-intensity chronic infections. Diagnostic challenges, however, lead to the omission of S. stercoralis in studies of soil-transmitted helminths and few studies focus on S. stercoralis, specifically. These factors lead to an underreporting of the nematode's prevalence, not only in South-East Asia but worldwide. We have reviewed the scientific literature of the last 25 years and estimated country-wide prevalence rates for South-East Asia. We aim to summarise what is known today about the prevalence of S. stercoralis in South-East Asia, as well as to ascertain the risk factors and diagnostic methods most commonly applied.