United States Geological Survey, Leetown Science Center, National Fish Health Research Laboratory
Kearneysville, WV, USA
Whirling disease is caused by the myxosporean parasite Myxobolus cerebralis and affects salmonid fishes worldwide. In the United States, M. cerebralis had been recognized as a pathogen of cultured salmonids since the 1950's. In the mid-1990's, however, population declines among wild rainbow trout in regions of the intermountain western U.S. were associated with the occurrence of whirling disease. This discovery brought about a resurgence of scientific interest and widened the scope of related research to address the disease in the wild. Over the past decade, whirling disease investigations have moved in a number of new directions while continuing to develop upon the foundation built by decades of previous research. Relatively novel avenues of whirling disease research include ecological and epidemiological approaches such as those that incorporate risk assessment and dynamic modeling tools to aid in our understanding of the occurrence of whirling disease in the natural environment. Environmental factors influencing infectivity of the pathogen and population distribution of the oligochaete host are receiving increased attention as key issues explaining differences in disease prevalence among wild fish. Molecular, genetic, and immunological techniques are also being increasingly incorporated to advance many segments of whirling disease research such as evaluation of disease pathogenesis and host immune responses as well as recognition of taxonomically based differences in salmonid and oligochaete host susceptibility.
Utafiti wa Jiolojia wa Marekani, Kituo cha Sayansi cha Leetown, Maabara ya Kitaifa ya Utafiti wa Afya ya Samaki, Kearnsville, WV, USA, ugonjwa wa Whirling unasababishwa na vimelea vya Myxobolus cerebralis na huathiri samaki wa salmonidi ulimwenguni kote. Katika miaka ya 1950, M. cerebalis iligunduliwa kuwa kiini cha magonjwa ya samaki aina ya salmon. Hata hivyo, katikati ya miaka ya 1990, idadi ya samaki hao ilipungua katika maeneo ya magharibi mwa Marekani, na hilo lilisababisha ugonjwa wa kuambukizwa na samaki hao. Ugunduzi huo ulileta tena maslahi ya kisayansi na kupanua utafiti unaohusiana na ugonjwa huo katika mazingira ya asili. Katika miaka kumi iliyopita, uchunguzi wa magonjwa ya mzunguko umeendelea katika mwelekeo mpya, huku ukiendelea kuendeleza msingi uliojengwa na miongo kadhaa ya utafiti wa awali. Njia mpya za utafiti wa magonjwa ya mzunguko ni pamoja na mbinu za ikolojia na magonjwa ya kuambukiza, kama vile zile ambazo zinajumuisha tathmini ya hatari na zana za kuunda mfano wa nguvu kusaidia katika uelewa wetu wa kutokea kwa magonjwa ya mzunguko katika mazingira ya asili. Vipengele vya mazingira vinavyoathiri maambukizi ya vimelea na usambazaji wa idadi ya mwenyeji wa oligochaete vinapata umakini mkubwa kama masuala muhimu yanayoelezea tofauti katika kuenea kwa ugonjwa kati ya samaki wa mwituni. Mbinu za molekuli, maumbile, na kinga pia zinajumuishwa zaidi ili kuendeleza sehemu nyingi za utafiti wa magonjwa ya mzunguko kama vile tathmini ya pathogenesis ya ugonjwa na majibu ya kinga ya mwenyeji, na pia utambuzi wa tofauti za taxonomically katika salmonid na oligochaete.