Onchocerciasis or river blindness is a disease caused by filarial worm Onchocerca volvulus in the human beings. This disease also known as craw craw is an endemic disease in Bioko Island, Equatorial Guinea.
The disease caused by black flies causes weakening in affected individuals and since most of the affected individuals belong to labor force population it serves as major block to the economic development of the island. The environmental conditions and altitude of Bioko favor the development of the disease. The parasite, in the form of larvae, is transmitted to the humans when the fly bites the humans to suck blood.
Female parasites are larger than the male parasites and live up to 10 to 15 years. The infection is manifested in the form tumors. The larvae of the parasite are distributed through the host's skin, eyes and other organs, especially skin and eyes, usually provoking blindness.
The work, carried out by the group of Hospital Clínic de Barcelona, was led by Dr. Jordi Mas of the Microbiology Unit of Hospital Clínic-Universitat de Barcelona, and Dr. Carlos Ascaso of the IDIBAPS Epidemiology and International Health Research Group. The objective of this study was to assess the impact of 8-year vertical distribution of Ivermectin, the only treatment available against onchocerciasis, among the rural population of 12 communities and two ethnical groups: the Bubis and the Fangs.
The fact that the administered drug dose is only effective on larvae, conditions the duration of this study. The study was carried out during 8 years, because this is precisely the maximum time of fertility of females, what guarantees the total elimination of the offspring.
This study, published in Tropical Medicine and International Health (11(7):1082-91), has been financed by the Spanish Agency of International Cooperation, and the World Health Organisation (WHO). It continues from the achievements of previous works held in Africa in order to assess Ivermectin effects and to determine the importance of onchocerciasis. Results are highly conclusive in this case: onchocerciasis prevalence before treatment was of 74.5%, and after treatment, 38.4%. Furthermore, we want to underline that after Ivermectin administration, the incidence of onchocerciasis in children aged 0-4 decreased 2.6 times.
The follow-up of this project created more than a decade ago by Dr. Jordi Mas continues to be in force by the Ministry of Health of Equatorial Guinea. Nevertheless, the monitoring of the state of the disease is conducted by the Catalan group from Barcelona and Bioko.
Future strategies of the fight against river blindness go further than the administration of Ivermectin. Currently, the vector of the disease is being eliminated by the WHO African Program for Onchocerciasis (APOC). Dr. Jordi Mas will soon travel to Bioko in order to test the effects of the new measures. The efficiency of these methods, the operation of the project, along with the results of the studies of the Hospital Clínic Group will be assessed in the near future in a joint meeting with the Ministry of Health of Equatorial Guinea, the WHO and Dr. Jordi Mas.