Lungworm Research Paper

For this essay, I chose to study lungworms. Lungworms, also known as Hoose or Husk, are parasitic nematode worms of the family Metastrongylidae, occurring in the lungs of mammals. The species that are affected by lungworms include all of the following: cattle, horses, sheep and goats, and pigs. However each species contracts a different type of lungworm; cattle contracts the viviparus lungworm, horses contract the arnfieldi lungworm, sheep and goats contract the filaria lungworm, and pigs contract the Metastrongylus apri lungworm. All of the listed types of lungworms can be known by other names. Dictyocaulus filaria is found in the bronchi of the lungs, whereas Protostongylus rufescens is in the smaller bronchioles, and Muellerius capillaris

The survival and infectivity of larvae on the pasture is affected by a number of environmental factors; with optimal conditions speeding up development. Larvae in pastures rapidly dry out in hot dry weather, but can survive within the dung pat. Their dispersal is facilitated by heavy rain, and the pilobolus fungus also plays an important role as it can propel larvae up to 3 metres away from the dungpat, as it expels its own spores. Livestock is generally more susceptible to contracting lungworms in Europe (cold and rainy), rather than in North America. The parasites thrive in the winter months and as the year goes on and the temperature rises, the parasite numbers and productivity drop dramatically. The lifecycle of lungworms is very meticulous. The general life cycle of a lungworm begins with an ingestion of infective larva/e. Once the infective larvae are consumed by grazing cattle they penetrate the intestinal wall and migrate through lymphatics and blood vessels, reaching the lungs after approximately seven days. Then the larvae mature and travel through the airways (adult worms are present in the trachea around twenty-five days after infection). Hatched larvae are then coughed up and swallowed, before being passed out onto pasture in the animal’s faeces. An average infection with two hundred larvae can lead to around seventy adult worms, which can result in 2.5 million infective larvae on the pasture as little as thirty days after the ingestion occurs. If young or naïve cattle are exposed to high pasture challenge without prior vaccination or sufficient low level exposure to have developed immunity, clinical disease will be seen. In older animals that have an established level of immunity low levels of pasture challenge will serve to boost this, but in the face of heavy, uncontrolled challenge, outbreaks of severe potentially fatal disease can also be seen in adult