MANSONELLA OZZARDI

OUTLINEIntroductionTaxonomic ClassificationMorphologyEpidemiologyLife CycleTransmissionManifestationLaboratory DiagnosisTreatment and Prevention

INTRODUCTIONMansonella ozzardi is a New World filaroid parasiteAdults live in the body cavity, within the mesenteries, peritoneum, and in subcutaneous tissuesInfected with WolbachiaIntermediate hosts are midges and blackflies

TAXONOMIC CLASSIFICATION Kingdom: Animalia Phylum: Nematoda Class: Secernentea Order: Spirurida Family: Filariidae Genus: Mansonella Species: Mansonella

ozzardi

MORPHOLOGYM. ozzardi is a cylindrical and bilaterally symmetrical worm, with a pseudocoel. Its exterior, the cuticle, is a protective layer that can withstand the harsh environment in the digestive tracts of the human hosts.M. ozzardi and other nematodes have longitudinal muscles that run along the body wall. They also have dorsal, ventral, and longitudinal nerve cords connected to these longitudinal muscles.Adult M. ozzardi are long and slender with reduced lips. Females are larger than males, and produce thousands of offspring called microfilariae.

MORPHOLOGYM. ozzardi microfilariae are 170-240 um long, unsheathed, and have a slender, clear, tapered tail called a "button hook." The nuclei do not extend to the end of the tail. When stained, the presence or absence of a sheath, internal nuclei and organs can all be seen, with the organization of these aiding in identification and classification of the different filarial worm species.

MORPHOLOGY

EPIDEMIOLOGYIt is prominent in the subtropical, tropical, and temperate regions of Central and South America (Mexico, Panama, Brazil, Colombia, and Argentina), and the CaribbeanIts prevalence rate varies from a few percent to 96% in endemic areas such as Trinidad, Guyana, and Columbia

LIFE CYCLE

TRANSMISSION M. ozzardi is transmitted by two types of arthropods that feed on the blood of humans: biting midges (genus Culicoides) and blackflies (genus Simulium).

Biting midges are small flies that breed on sandy beaches near the sea

Blackflies are larger blood-sucking flies that breed in fast-flowing streams and rivers.

MANIFESTATIONThe pathogenicity of M. ozzardi needs further research.Although the adult worms live in the body cavities and the mesentery, they seem to cause little or no harm to their human hosts. Infected people rarely present any symptoms. However, a few clinical manifestations have been reported:1. Moderate fever

2. Coldness in the legs3. Joint pains, like articular pain or

arthralgias4. Headaches5. Pruritus (itchiness)6. Skin eruptions

7. Pulmonary symptoms8. Lymphadenitis - inflammation of

the lymph nodes9. Adenopathy - enlargement of the

lymph nodes10. Hepatomegaly - enlargement of the

liver

LABORATORY DIAGNOSISMicroscopic examination is the most practical diagnostic tool used to identify the M. ozzardi microfilariae in blood samples from infected patients. Since the microfilariae are not periodic, periodicity is not a factor in taking the blood sample. Blood smears are usually stained with haematoxylin and eosin or Giemsa to visualize the worms under the microscope.

TREATMENT AND PREVENTION

Ivermectin is the treatment of choice for M. ozzardi infections. Diethylcarbamazine (DEC) also has been used in treating filarial infections but is not effective in treating M. ozzardi microfilarial infections.Individuals living in endemic areas such as the Caribbean should wear long-sleeved shirts and pants to decrease the exposed body parts.Insect repellents could also be used to cover body parts not protected by clothing.Communities should also maintain the natural vegetation around them to decrease the possible breeding grounds for the biting midges.In South America, the best way to control the population of blackflies, and the transmission of M. ozzardi, is to apply insecticides specific for blackfly larvae to streams and rivers.