Summary
Highlights
Dirofilaria immitis, commonly known as canine heartworm, is a vector-borne nematode primarily affecting dogs. These worms reside in the right ventricle of the heart and pulmonary artery, causing significant cardiovascular pathology. Mosquitoes (Culex, Aedes, Anopheles) act as intermediate hosts, transmitting the larval stage (microfilariae) after ingesting them from an infected dog. In the mosquito, microfilariae develop into infective larvae. When an infected mosquito bites another dog, these larvae enter the new host. Heavy infections can lead to pulmonary hypertension, right ventricular enlargement, congestive heart failure, and clinical signs such as coughing, reduced stamina, and anemia. Diagnosis involves blood smear examination for microfilariae and serological tests. Treatment targets both microfilariae and adult worms, with mosquito control being crucial for prevention.
Stephanofilaria assamensis utilizes the Musca conducens fly as an intermediate host and is a common cause of 'humpsore' or verminous dermatitis in cattle, particularly in Assam and West Bengal. This chronic skin condition is characterized by small papules that coalesce into large, crusted lesions, causing intense itching, hyperkeratosis, acanthosis, and alopecia. The lesions can bleed easily and grow outwardly, often disappearing in dry seasons and reappearing in the rain. Diagnosis is confirmed by deep skin scrapings, and treatment involves topical application of trichlorfon ointment, alongside fly control.
Parafilaria bovicola infects cattle and buffalo, residing in intramuscular and subcutaneous tissues. Musca lusoria flies serve as intermediate hosts. This parasite causes 'summer bleeding,' characterized by hemorrhagic nodules on the skin, typically seen on the shoulders, withers, and neck. Gravid female worms migrate towards the dermis for egg-laying, leading to enlarged, painful, and bleeding nodules. Treatment includes nitroxynil and fenbendazole or albendazole. Control focuses on managing fly populations.
Dirofilaria repens primarily affects dogs and cats, residing in subcutaneous tissues. Its microfilariae circulate in the blood and lymph. Transmitted by mosquitoes, it can occasionally infect humans, leading to ocular problems. Dipetalonema reconditum, less pathogenic than D. immitis, resides in the body cavity and subcutaneous tissues of dogs. Unlike D. immitis, its life cycle involves fleas, ticks, or lice as intermediate hosts. Although its microfilariae can be mistaken for heartworm microfilariae, specific morphological differences aid in differentiation. Generally, D. reconditum infections do not require treatment, but ivermectin can eliminate microfilariae.
Setaria digitata, a member of the Setariidae family, is a mosquito-borne filarial nematode common in cattle and buffalo. While adult worms typically reside in the peritoneal cavity without significant harm, abnormal migration of immature stages in accidental hosts (sheep, goats, horses) can cause 'kumri' or lumbar paralysis, a severe neurological condition. Clinical signs include muscular weakness, ataxia, hindlimb paralysis, and sometimes blindness. Treatment typically involves diethylcarbamazine, and control strategies focus on mosquito management.
Onchocerca gibsoni affects cattle, found in the brisket area and external surfaces of hind limbs. It is transmitted by biting midges (Culicoides spp.). Microfilariae are found in skin tissue spaces, diagnosed via skin biopsy. Treatment includes diethylcarbamazine, with control focusing on reducing fly populations. Onchocerca volvulus primarily infects humans, transmitted by black flies (Simulium spp.). It causes 'river blindness' and associated skin conditions. Treatment involves ivermectin, emphasizing black fly control.
Onchocerca armillata is a cattle parasite, diagnosed through skin samples or post-mortem examination. It is more common in younger males and severely damages major arteries like the thoracic aorta and its branches, leading to significant pathological changes within the circulatory system. Control relies on vector management and integrated disease management strategies to mitigate its impact on cattle health.
Tetrameres mohtedai is a common poultry nematode belonging to the Tetrameridae family, known for its distinct sexual dimorphism. Females are spherical, blood-red, and deeply embedded in the glandular lining of the proventriculus and gizzard, while males are slender, thread-like, and white, found freely in the proventriculus lumen. Transmitted by insects like cockroaches and grasshoppers, it causes anemia, weight loss, and thickening of the proventriculus walls in birds, particularly young ones. Treatment involves piperazine adipate, and control emphasizes preventing birds from consuming intermediate hosts and rearing them in caged systems.