Mansonelliasis - Infectious Disease

Overview of Mansonelliasis

Mansonelliasis is a neglected tropical disease due to the infection of various species of filarial nematode parasites of the genus Mansonella. These parasites mainly infect humans as the definitive hosts and necrobiotic transmission occurs due to blood feeding dipteran insects like biting midges and blackflies. The three most important species responsible for human mansonelliasis are Mansonella perstans, Mansonella ozzardi, and Mansonella streptocerca, each with distinct features.

M. perstans is regarded as the most widely distributed species of the Mansonella genus, occurring in all sub-Saharan African countries and the Amazon basin in South America. M. ozzardi is more patchily distributed in Latin America and the Caribbean, whereas M. streptocerca has a distribution in central and west Africa. With these infections, most cases are asymptomatic. The patients may present with moderate symptoms like itch, arthralgia ,and lymphadenopathy.

Life cycle of three species of Mansonella spp.

Fig.1 Integrated life cycle of the three Mansonella spp. (Ta-Tang T.H., et al., 2021)

Vaccine Development for Mansonelliasis

Though mansonelliasis bears a high public health burden, particularly in the low-income parts of the world, its vaccine development has fallen behind other neglected tropical diseases in comparison to other filarial infections such as lymphatic filariasis and onchocerciasis. The lack of progress in the field can be attributed to several factors:

Lack of Defined Protective Antigens

Relative to the information available on other human filarial nematodes, little is known of Mansonella parasites from the aspects of biology and immunology. There exist considerable difficulties in determining vaccine target antigens capable of inducing a protective immune response. The life-cycle, molecular structure of the parasite, and interactions with the host need further characterization.

Heterogeneity of Mansonella Species

The three Mansonella species that are responsible for mansonelliasis differ in their geographic distribution, vector transmission, and even in their genetic composition. The development of a single vaccine, which is able to cover this whole diversity sounds very challenging from a technical point of view. It may be necessary to take a species-specific or even strain-specific vaccine designing approach.

Limited Animal Models

The absence of fitting animal models that realistically replicate mansonelliasis is recognized. Most of the laboratory work has depended on the use of rodent or nonhuman primate experimental infections, which leaves much to be desired in terms of how well the natural disease process and immune responses are modeled. This limits the assessment and fine-tuning of vaccine candidates.

Therapeutics Development for Mansonelliasis

Microfilarial Clearance
Medications such as diethylcarbamazine (DEC) and ivermectin have been used to eradicate microfilariae bloods. These drugs target the offending organism with their direct action, thus achieving reduction in numbers and symptomatic relief.
Over the years it has been demonstrated that the combination of DEC and ivermectin is more effective in decreasing microfilarial loads as opposed to single-agent therapy.

Anti-Wolbachia Therapies
Due to the vital importance of Wolbachia endosymbionts in sustaining the parasites, antibiotics like doxycycline proved successful as they eliminate these bacteria, clearing the infections from the body.
The human trials have shown that doxycycline is effective for the treatment of Mansonella Infections, most importantly M. perstans, owing to the removal of the Wolbachia endosymbionts.

Our Services

As a research service provider, Protheragen's drug discovery scientists are taking a multi-pronged approach to address the unmet need for more effective and safer therapeutics for mansonelliasis.

We employ cutting-edge technologies such as next-generation sequencing and high-throughput screening to accelerate the discovery process. Our team of scientists has extensive experience in working with neglected diseases, ensuring that our approach is scientifically sound. If you are interested in our services, please feel free to contact us.

References

Ta-Tang, Thuy-Huong, et al. "An overview of the management of mansonellosis." Research and reports in tropical medicine (2021): 93-105.
Ta-Tang, Thuy-Huong, et al. "Mansonellosis: current perspectives." Research and reports in tropical medicine (2018): 9-24.

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