Central Asia's hidden burden of neglected tropical diseases.

Abstract

The neglected tropical diseases (NTDs) are the most common infections of the world's poorest people living in developing countries [1]–[7]. They are mostly comprised of chronic parasitic and related infections, with the most common NTDs represented by the soil-transmitted helminthiases, schistosomiasis, lymphatic filariasis, onchocerciasis, and trachoma [1]. Among their common features, the NTDs result in prolonged periods of disability and actually help to promote poverty through their long-standing effects on child development and worker productivity [2]. It is not commonly appreciated that the NTDs are widespread throughout Central Asia where they are also a major determinant of poverty [8]. The five mostly landlocked Central Asian countries—Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan (Figure 1)—were established upon the breakup of the former Soviet Union in 1991. They are also linked in history as a vital crossroads (“the Silk Road”) between Asia and Europe and by a common geography comprised of a desert and piedmont region [9]. The five nations have a combined population of 60 million people, with three of them—Kyrgyzstan, Tajikstan, and Uzbekistan—exhibiting a Human Development Index (HDI) that is ranked below 100, whichis more or less equivalent to nations such as Guatemala, India, Indonesia, and South Africa [10]. Figure 1 Commonwealth of Independent States - Central Asian States. During the Soviet era in the 20th century, some gains were made in parasite and NTD control. For instance, in Uzbekistan a number of NTDs were either eradicated or eliminated as a public health problem, including dracunculiasis in 1931, urban cutaneous leishmaniasis in 1950, malaria in 1960, visceral leishmaniasis in 1968, and hookworm infection in 1974 [11]. However, following the 1991 breakup of the Soviet Union, public infrastructures and services deteriorated in many areas of Central Asia, and breakdowns in health care and preventive services ensued [12]. Of particular relevance to zoonotic NTDs and according to Torgerson et al., the Soviet breakup also meant that large mechanized slaughterhouses were closed, leaving livestock production in the hands of small farms and unsupervised homes, and largely without veterinary inspection [13], [14]. Together with increases in pet and security dogs, veterinary public health was compromised, with a resultant re-emergence of several important NTDs, including echinococcosis and possibly toxocariasis [13]–. As a result, today several NTDs either remain widespread in Central Asia or may have even increased in prevalence over the last two decades. They include the soil-transmitted helminth infections, food-borne and zoonotic parasitic infections, and vector-borne protozoan infections (Table 1). Table 1 Selected Neglected Tropical Diseases in Central Asia.