Mansonella sp

Introduction

Members of the genus Mansonella are filarial nematodes which rarely cause serious disease.  However, they can be found in geographical areas where Wuchereria bancrofti , Loa loa  and Onchocerca volvulus also occur and therefore must be differentiated from these pathogenic microfilariae.  Unlike the pathogenic blood filariae, they do not exhibit periodicity.

Life cycle

Morphology

The adult worms live in the peritoneal, pleural and pericardial cavities and their size is comparable to the pathogenic species already discussed. The microfilariae are unsheathed are about 200m in length and the nuclei extend to the tip of the tail which is rounded.

Clinical disease

It is difficult to assess the disease associated with M. perstans, however pruritis, fever and subcutaneous swellings have been associated with infection of M. perstans.  The adult worm appears to cause little or no host reaction. Eosinophilia is common.

• Mansonella ozzardi

M. ozzardi is confined to the New world and West Indies. 

Morphology

The adult worms are located in the mesenteric tissues and their size is comparable to the pathogenic species already discussed.  The microfilariae are found in the peripheral blood and range between 173 - 240m in length.  The nuclei do not extend to the tip of the tail which has a pointed end.

Clinical disease

Infections caused by M. ozzardi are generally symptomless, however lymphadenopathy, arthralgia, fever  and eosinophilia have been reported.