Written by Achmad Naufal Azhari - NPO (Neglected Tropical Diseases).
Schistosomiasis, also known as Bilharzia or snail fever disease, is one of the oldest and most debilitating neglected tropical diseases (NTDs). It is transmitted when larval forms released by freshwater snails penetrate human skin during contact with infested water.
There are two major forms of schistosomiasis: intestinal and urogenital. Intestinal schistosomiasis is common in South East Asia and Western Pacific regions and it can cause abdominal pain, diarrhoea, and blood in the stool. Majority of chronic schistosomiasis patients show liver enlargement. Spleen enlargement and fluid build up in the abdomen are also observed at the last stage of the disease and it may lead to death. Meanwhile, urogenital schistosomiasis, which is not prevalent in Indonesia, is signified by the presence of blood in urine.
Fig. 1. National Professional Officer (NPO) for Neglected Tropical Diseases (NTDs) Programme in WHO Indonesia observes the stool examination process during schistosomiasis prevalence evaluation survey in Schistosomiasis Laboratory, Lore Utara, Poso District, 26 May 2022. Photo Credit: Azhari/WHO
Schistosomiasis is caused by several species of trematodes, namely Schistosoma haematobium, S. mansoni, and S. japonicum. In Indonesia, Schistosoma japonicum has been found to be prevalent only in three isolated areas in Lindu, Napu, and Bada Highlands in Central Sulawesi Province and it is transmitted to humans by an intermediate snail, Oncomelania hupensis lindoensis.
Based on the report of the Ministry of Health, the disease prevalence decreased gradually from 1.66% in 2013 to less than 1% in 2016 in all areas. This is a progress as it fits the criteria to achieve elimination as a public health problem: less than 1% of heavy infection. This situation was maintained until 2021. Twelve out of 28 villages in the area have been reporting zero case in three consecutive years since 2019.
During the Ministry of Health’s mission in Central Sulawesi in 22-27 May 2022, the prevalence evaluation survey targeted at least 80% of population at risk who live in four endemic villages with total samples from around 1,700 people. WHO Country Office Indonesia provided technical support to the National NTDs Programme, Ministry of Health in organizing this survey.
Due to the absence of antigen/antibody-based diagnostic kit for screening of S. japonicum, each eligible person collected their stool in three consecutive days. Laboratory technicians from Donggala Institute for Health Research and Development then processed sample from each respondent into 3 slides everyday, resulting in 13,077 specimens that are examined with a microscope to identify the presence of schistosoma eggs.
Lack of community participation in stool survey is the main challenge in recent decade. The natives in endemic villages have been tired of collecting stool during the survey every year. On the other hand, there is very limited evidence on the performance of any point of care test for S. japonicum.
To address this issue, health workers approached the chief of endemic village and cadres to perform programme sensitization to all villagers and encourage them to collect stool specimen during the survey. As mandated in the national schistosomiasis roadmap, local health authorities in collaboration with village department also conduct health promotion activities in routine basis. In addition, Ministry of Health and WHO are identifying potential alternative test kit for schistosomiasis elimination programme.
Currently, Donggala Institute for Health Research and Development is analyzing the result of this survey. The interim report on 17 June 2022 showed that there were fourteen confirmed positive cases, localized only in two endemic villages.
This means Indonesia is in the last miles of its schistosomiasis elimination. As per elimination criteria in the WHO’s 2021-2030 Global NTDs Roadmap, an endemic area achieve the elimination of schistosomiasis as a public health problem by recording less than 1% proportion of heavy intensity infection for several years and entering the next milestone, which is interruption of transmission.
The prevalence evaluation survey is important because it can help drive decisions on the status of schistosomiasis in certain area. The final survey result will be available in the end of July and reported to the National NTDs Programme and WHO. Technical officer for schistosomiasis programme in the Ministry of Health will monitor and follow-up the survey.
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