Spatial distribution of Taenia solium exposure in humans and pigs in the Central Highlands of Vietnam

Abstract

BackgroundTaenia solium, a pork-borne parasitic zoonosis, is the cause of taeniasis and cysticercosis in humans. In Vietnam, poor sanitation, the practice of outdoor defecation and consumption of raw/undercooked pork have been associated with infection/exposure to T. solium in both humans and pigs. The broad-scale geographic distribution of the prevalence of T. solium varies throughout the country with infection restricted to isolated foci in the north and a more sporadic geographic distribution in the Central Highlands and the south. While cross-sectional studies have allowed the broad-scale geographic distribution of T. solium to be described, details of the geographic distribution of T. solium at finer spatial scales have not been described in detail. This study provides a descriptive spatial analysis of T. solium exposure in humans and pigs and T. solium taeniasis in humans within individual households in village communities of Dak Lak in the Central Highlands of Vietnam.Methodology/Principal findingsWe used Ripley’s K-function to describe spatial dependence in T. solium exposure positive and negative human and pig households and T. solium taeniasis exposure positive and negative households in villages within the districts of Buon Don, Krong Nang and M’Drak of Dak Lak province in the Central Highlands of Vietnam. The prevalence of exposure to T. solium in pigs in Dak Lak province was 9 (95% CI 5 to 17) cases per 1000 pigs at risk. The prevalence of exposure to the parasite in humans was somewhat higher at 5 (95% CI 3 to 8) cases per 100 individuals at risk. Spatial aggregations of T. solium exposure-positive pig and human households occurred in some, but not all of the villages in the three study districts. Human exposure-positive households were found to be aggregated within a distance of 200 to 300 m in villages in Krong Nang district compared with distances of up to 1500 m for pig exposure-positive households in villages in M’Drak district. Although this study demonstrated the aggregation of households in which either T. solium exposure- or taeniasis-positive individuals were present, we were unable to identify an association between the two due to the very low number of T. solium taeniasis-positive households.ConclusionsSpatial aggregations of T. solium exposure-positive pig and human households occurred in some, but not all of the villages in the three study districts. We were unable to definitively identify reasons for these findings but speculate that they were due to a combination of demographic, anthropological and micro-environmental factors. To more definitively identify characteristics that increase cysticercosis risk we propose that cross-sectional studies similar in design to that described in this paper should be applied in other provinces of Vietnam.

Vietnam: Neglected tropical diseases in an emerging and accelerating economy

“…Together with open defecation using outdoor latrines, the use of night soil for agriculture maintains or accelerates this infection [47]. Similar to aquaculture, husbandry makes up a large percentage of Vietnam's gross domestic product (GAU : PleasenotethatGD DP) and produces nearly 3,800 million tons of meat products annually [64]. Two primary types of pig and cattle husbandry practices exist: commercial farming and backyard husbandry.…”

The epidemiology of human Taenia solium infections: A systematic review of the distribution in Eastern and Southern Africa

“…T. solium is endemic in Africa, Asia and Latin America, especially in areas where pigs are reared under free-ranging conditions, where pork is eaten and where hygiene is limited [8][9][10]. Nevertheless, information on the endemicity of T. solium is limited and there are many countries from which no published information is available for either human or porcine Comoros, Djibouti, Eritrea, Ethiopia, Kenya, Lesotho, Madagascar, Malawi, Mauritius, Mayotte, Mozambique, Namibia, Reunion, Rwanda, Seychelles, Socotra, Somalia, Somaliland, South Africa, Eswatini (former Kingdom of Swaziland), Tanzania, Uganda, Zambia and Zimbabwe.…”

The epidemiology of humanTaenia soliuminfections: a systematic review of the distribution in Eastern and Southern Africa

“…T. solium is common in Asia and Latin America, especially in areas where pigs are reared under free-ranging conditions, where pork is eaten and where hygiene is limited [8,9]. Hence, T. solium is also likely endemic in most African countries [10].…”