Mansonella

A parasitic nematode causing mansonelliasis

Mansonella ozzardi is a parasitic nematode that causes the disease known as mansonelliasis. It is transmitted to humans through the bite of infected biting midges and blackflies. This parasite is primarily found in the Neotropics, including regions of Central America, South America, and the Caribbean.

Morphology

Mansonella ozzardi is a small filarial worm that resides in the subcutaneous tissues of its host. The adult worms are thread-like, with females measuring up to 70 mm in length and males being slightly shorter. The microfilariae, which are the larval stage, are unsheathed and can be found in the blood of infected individuals.

Life Cycle

The life cycle of Mansonella ozzardi involves two hosts: a human host and an insect vector. The adult worms reside in the subcutaneous tissues of humans, where they produce microfilariae. These microfilariae circulate in the blood and are ingested by a biting midge or blackfly during a blood meal. Inside the insect vector, the microfilariae develop into infective larvae, which are then transmitted to a new human host when the insect takes another blood meal.

Epidemiology

Mansonella ozzardi is endemic to the Neotropical regions, with significant prevalence in the Amazon Basin, parts of Brazil, Colombia, Venezuela, and the Caribbean islands. The distribution of the disease is closely linked to the habitats of the insect vectors, which thrive in tropical and subtropical climates.

Clinical Manifestations

Infection with Mansonella ozzardi is often asymptomatic, but some individuals may experience mild symptoms such as itching, joint pain, and skin rashes. In rare cases, more severe symptoms can occur, including lymphadenopathy and eosinophilia.

Diagnosis

Diagnosis of mansonelliasis is typically made by identifying the microfilariae in a blood smear. The microfilariae of Mansonella ozzardi are unsheathed and can be distinguished from other filarial species by their size and morphology.

Treatment

The treatment of choice for Mansonella ozzardi infection is ivermectin, which is effective in reducing the microfilarial load. In some cases, diethylcarbamazine (DEC) may also be used.

Prevention

Preventive measures include reducing exposure to the insect vectors through the use of insect repellent, protective clothing, and insecticide-treated nets. Control of the vector population through environmental management and insecticide spraying can also help reduce transmission.

Related pages

• Mansonelliasis
• Filarial nematode
• Vector (epidemiology)