The first of four papers reviews elimination and control programmes. Subsequent papers will describe the integration, mapping, and financing of international control initiatives. The series is introduced by a commentary article from David Molyneux of the Centre for Neglected Tropical Diseases, Liverpool School of Tropical Medicine, who is well known as an active campaigner for action against NTDs to be stepped up. A podcast and a profile of Professor Molyneux also form part of the series.

The Lancet is not an open-access journal. However, as with many of its articles on global health topics, the series may be viewed freely online. (Registration is required.)

But we can find no further references to the existence of World Filariasis Day. TropIKA.net readers who have heard something about it are asked to let us know.

The TropIKA.net blog has often commented on the rapidly growing number of special “Days” held in an attempt to focus attention on particular diseases. (The most recent was World Pneumonia Day - 2nd Nov.) It could be argued that there are already more than enough such Days. But lymphatic filariasis (and onchocerciasis, which is also caused by filarial worms) are severely neglected diseases. Would a World Filariasis Day help to bring an end to this neglect?

Two infectious diseases are important causes of blindness in many parts of Africa - trachoma and onchocerciasis. The sampling used for the Nigerian study included clusters in areas where these diseases are known to be endemic. However, neither disease was found to be a significant cause of blindness. Overall, trachoma was responsible for 4.2% of blindness and onchocerciasis for 1.1%. To quote the authors:

“There are several possible explanations for our findings: First, both onchocerciasis and trachoma are focal diseases, and the clusters selected even in endemic areas may, by chance, have not included areas with the highest endemicity. Second, there may have been misclassification: For example, corneal scarring from trachoma may have been misclassified as nontrachomatous, but this seems unlikely, and corneal opacity, chorioretinitis and optic atrophy may not have been attributed to onchocerciasis. Third, the findings may reflect a genuine decline in blindness from these two diseases, particularly that due to onchocerciasis as a consequence of the Africa Onchocerciasis Control Programme (APOC).”

While the findings of the study suggest that there are fewer cases of blindness due to infection in Nigeria than might have been predicted, the blindness situation in the country is of great concern. The researchers conclude that blindness is increasing and that the number of visually impaired adults will increase by 40% in the next decade. They highlight the issue of poor access to health services as a major factor. The vast majority of causes are either preventable or treatable and groups with less access to health care were found to be particularly vulnerable to preventable visual impairment. The authors recommended vision care plans that target women, rural residents and the less educated.

However, the article also makes it clear that , drawing on the lessons learnt with onchocerciasis, there is now a need for further research to develop new treatments for other infectious diseases of poverty.

The purpose of the disease mapping consultancy is “to conduct or improve disease mapping of the selected neglected infectious diseases (NIDs) that can be targeted through mass drug administration (MDA), i.e. onchocerciasis, lymphatic filariasis, schistosomiasis, soil-transmitted helminthiasis, and trachoma, as well as other diseases that could be part of an integrated plan, including Chagas disease, rabies transmitted by dogs, plague, leprosy, leishmaniasis, and congenital syphilis, among others”. Details are available here.

The purpose of the social determinants consultancy is “to analyze the social determinants of health associated with neglected infectious diseases (NIDs) (i.e. living conditions, cultural factors, etc.), as well as possible key interventions to mitigate them in order to reduce the burden of selected NIDs that can be targeted through mass drug administration (MDA)—i.e. onchocerciasis, lymphatic filariasis, schistosomiasis, soil-transmitted helminthiasis, and trachoma—as well as other diseases that could be part of an integrated plan, including Chagas disease, rabies transmitted by dogs, plague, leprosy, leishmaniasis, and congenital syphilis, among others”. Details may be found here.

CDI was successfully developed by the African Programme for Onchocerciasis [river blindness] Control (APOC) and it has been shown to be also appropriate in other situations - see article on the TDR website.

Meeting in Nigeria’s capital city, Abuja, the Vice Chancellors said that they would begin to train doctors about CDI later this year (or in some cases next year.)

Nigeria’s Minister of State for Health, Dr Aliyu Idi Hong said health interventions succeeded better when community members were involved in their planning and implementation.

LSTM has established a global consortium of six academic and industrial partners, called the Anti-Wolbachia Consortium, to screen and develop new combinations of potential filariasis drugs. [Wolbachia are bacteria which filarial worms need to survive.]

Researcher Mark Taylor said: “Drug resistance is making current treatment programmes less effective in areas where the disease had virtually disappeared. Ivermectin [the mainstay of efforts to control filarial disease] is a fantastic drug, but as with any control approach, it is dangerous to rely on a single tool. Unless we come up with a new treatment, it could mean that the major source of blindness in Africa will become untreatable.”

At present, insecticides are used for blackfly control but a biological agent would be preferable. New research has identified a possible candidate - a non-biting midge, Cardiocladius oliffi.

In a study reported in Parasites & Vectors (1) researchers observed in the lab that larvae of the midge appeared to feed on egg masses of Simulium squamosum. The researchers went on to rear further Cardiocladius oliffi midges and found that they were able to significantly reduce the number of adult blackflies that developed from egg masses. They conclude that: “Cardiocladius oliffi has been demonstrated as potential biological control agent against S. squamosum“.

Several species of Simulium are able to transmit onchocerciasis, most notably S. damnosum. Further research will clearly be needed.

Reference
1. Boakye DA, Fokam E, Ghansah A, Amakye J, Wilson MD, Brown CA (2009). Cardiocladius oliffi (Diptera: Chironomidae) as a potential biological control agent against Simulium squamosum (Diptera: Simuliidae). Parasit Vectors. 2009 Apr 24;2(1):20. [Epub ahead of print]

Trachoma, another major cause of blindness has been found to be at particularly high levels in the southern Sudan, which has also been blighted by decades of war (1).

In a war zone it is hard to provide care to individual patients and harder still to run control disease programmes. Deaths and injuries resulting directly from conflict cause much damage in Africa and elsewhere but the indirect consequences, resulting from the disruption of health care, are probably much greater and much harder to calculate.

Reference
1. Ngondi J, Ole-Sempele F, Onsarigo A, Matende I, Baba S, et al. (2006). Blinding Trachoma in Postconflict Southern Sudan. PLoS Medicine; 3(12) e478 doi:10.1371/journal.pmed.0030478