Linguatula serrata, a food-borne zoonotic parasite, in livestock in Bangladesh: Some pathologic and epidemiologic aspects

Food-borne parasitic zoonoses are major threats to human health and only next to the 'big three' such as AIDS, tuberculosis and malaria. Linguatula serrata is a food-borne zoonotic pentastomid that affects a wide range of animals including humans. Dogs and other carnivores are the final hosts while most herbivores, including domestic ruminants serve as intermediate hosts. Here, the study was conducted on some epidemiologic and pathologic aspects of L. serrata infection in cattle and goats through a slaughterhouse based survey. A total of 302 samples, consisting of 257 mesenteric, 26 hepatic and 19 pulmonary lymph nodes (LNs) of cattle and goats were collected. Out of 302 LNs, 136 (45.0%) were infected with the nymphal stage of L. serrata (50.7% of cattle and 31.0% of goats). Significantly, a higher (P = 0.002) rate of infection was detected in cattle. Sex, but not seasons, is a prominent determinant of the infection. The infection was mostly detected in the mesenteric LNs (MLNs) (50.9%) but the parasite was also detected in the hepatic (3.9%) and pulmonary (21.1%) LNs. Grossly, the affected LNs were enlarged, edematous and soft. Cut surface of the LNs showed spongy appearance, and sometimes nymphs were found to crawl out. Histopathological studies revealed severe damage in parenchyma of LNs, characterized by the loss of typical pattern of lymphatic follicles and trabecule. Massive infiltration with eosinophils was detected. Collectively, the data suggest that L. serrata infection is endemic in food animals and has significant pathological impacts on livestock, and people of the country are at high risk to linguatulosis.