A case of recurrent human Dirofilaria repens infection in Uzbekistan

Dirofilaria repens is a zoonotic mosquito-borne filarioid that parasitizes in the subcutaneous tissues of carnivores, that has been incriminated in the great majority of human dirofilariasis cases reported throughout the Old World. From the Republic of Uzbekistan, recent data showed that this parasite is endemic in domestic and wild carnivores. In contrast, information regarding human infection is scarce and mostly outdated, with a single case report being published during the last decades. The present paper reports a case of recurrent autochthonous infection with D. repens in a patient living in the rural area of the Sirdaryo Region of Uzbekistan and having no international travel history. The first diagnosis was in 2019, when the patient presented with what was suspected to be a tumour of the left breast. Three years later, in 2022, she presented for a consultation after experiencing redness, occasional swelling and persistent itching in the umbilical region of the abdomen. The ultrasound indicated the presence of a living, motile nematode. Following anthelmintic therapy, the parasite was surgically removed and identified as a female D. repens. The present report highlights the possibility of human re-infection with D. repens and further underlines the necessity of raising public awareness and implementing of solid control strategies in carnivores.

Ecological and faunal characteristics of helminths of wetland birds in North-Western Uzbekistan

The article studies some faunistic features of helminths of wetland birds in the ecological crisis zone in North-Western Uzbekistan. Parasites of wetland birds collected in the basin of the lower reaches of the Amu Darya during the hunting seasons of 2018–2022 were used as material for this work. 500 individuals of birds representing 39 species from 24 genera, 13 families and 9 orders were examined using the parasitological dissection method. The article discusses the distribution and ecology of the helminths in the studied groups of birds. A total of 112 helminth species were identified in the region – 28 species belong to the class Cestoda, the class Trematoda is represented by 57 species, Nematoda – 23 and Acanthocephala – 4 species. 92 species of heminths were identified in the study area for the first time. The work provides original data on the structure of the helminth fauna from 9 orders of wetland birds. Various paths of helminth transmission in the circulation of infection were specified. The researchers identified four ways parasites use to enter their definitive host: helminths penetrate the host’s body when the latter eats other organisms, intermediate or reservoir hosts of helminths, which are part of the definitive’s host’s diet; helminths enter the host as mechanical impurity to food or water; they make active efforts to penetrate their host; helminths are transmitted by the intermediate host when the latter forages on the definitive host. Most of intermediate hosts for representatives of the class Cestoda were crustaceans – inhabitants of different types of water bodies; Oligochaeta are also included here as second or reservoir hosts. The development of trematodes occurs with the participation of aquatic molluscs acting as the first intermediate host. Various species of insects, fish, amphibians, reptiles and small mammals were identified as the second hosts. Nematoda use a wider range of intermediate hosts (Oligochaeta, crustaceans, insects – aquatic and terrestrial). Fish and amphibians were registered as the second and reservoir hosts of nematodes. The food chains of individual orders of wetland birds largely determine the composition of helminths parasitising them and are the main factor in the formation of their helminth fauna. These processes undoubtedly occur in time and space under the strict control of environmental factors.

Life cycle of Bilharziella polonica (Trematoda, Schistosomatidae) parasite of semi-aquatic birds in Uzbekistan

Schistosomatidae are an actively studied ecological group of trematodes. Their ability to cause various parasitic diseases in animals and humans makes them an interesting object of study for a number of research centres worldwide. One of the commonest species in this group is Bilharziella polonica (Kowalewsky, 1895), whose mature stages have been recorded in aquatic and semi-aquatic birds in Uzbekistan. Our research team established that the following birds were infected with mature trematodes B. polonica: Anas platyrhynchos (23%), A. crecca (18%), Podiceps ruficollis (11%), Ardea cinerea (14%) and one individual of Oxyura leucocephala. The highest infection rate was shown by the mallard A. platyrhynchos (23%) and common teal A. crecca (18%). The infection intensity ranged between 2 and 27 individuals. Research into various types of water bodies in Karakalpakstan identified 10 mollusc species – Lymnaeidae (4 species), Planorbidae (4 species) and Physidae (2 species). Cercariae morphologically similar to larvae of B. polonica were found in two species, Planorbis planorbis and P. tangitarensis. 6 chicks of domestic ducks were experimentally infected with those cercariae to track the life cycle of B. polonica in the organism of a definitive host. Helmintholological dissections showed that every duck was infected with B. polonica, which became mature 23–27 days after the infection. Eggs of B. polonica were recorded in the excrement of one of the birds 33–35 days after the infection. Based on field and experimental research, we identify the mollusc P. tangitarensis as a new intermediate host for B. polonica in Uzbekistan.