Eliminating Neglected Tropical Disease

choi

The article is very long, consisting three pages in print. There is no need to read the article itself. Drug mechanism will be in postings tomorrow.



Neglected tropical disease l Winning the Endgame; The remarkable tale of the global offensive against a variety of ancient plaques. Economist, Apr 22, 2017.
http://www.economist.com/news/in ... agues-global-attack

Quote:

"Buruli ulcer, Chagas disease, guinea-worm disease, leishmaniasis, river blindness, trachoma 沙眼 and yaws are some of the 18 now collectively referred to as 'neglected tropical diseases' (NTDs).

"In the 1950s and 1960s, China eliminated lymphatic filariasis ['sometimes known as elephantiasis'] by adding an anti-parasitic drug to table salt. For sleeping sickness, surveillance and 'vector control' (such as spraying with insecticide and setting insect traps) were highly effective.

"The benefits went far beyond the direct elimination of the suffering caused by these conditions' symptoms. As fewer people were rendered disabled, more could work. Dr [David] Molyneux[, a parasitologist with the Liverpool School of Tropical Medicine,] says it is now thought that one of the reasons Japan and South Korea developed so fast after the second world war is that both ran major deworming programmes in schools.

"The turning-point for NTDs came with the discovery of the drug ivermectin in the 1970s [by Merck] * * * William Campbell, one of the firm's parasitologists, thought it might be effective against the parasite that caused river blindness, which is endemic in parts of Africa and Latin America, and in Yemen. In its early stages river blindness causes rashes and severe itching; later, it progressively damages the retina. * * * The first human trial of ivermectin for river blindness was in Senegal in 1981, in patients who had the early stages of the disease but no damage to their eyes. Together with several more trials, it showed that ivermectin was safe in humans and highly effective at killing the disease vector in its larval state. But Merck had a problem: there was no market for it. Those who needed ivermectin were too poor to buy it. So the firm did something remarkable [in 1987]: it made an open-ended commitment to give away as much of the drug as necessary, starting in 1987

"International institutions such as the World Bank and World Health Organisation (WHO) teamed up with donor governments and charities. By 1999 the Gates Foundation, a charity set up by Bill and Melinda Gates, was funding work in lymphatic filariasis and schistosomiasis * * * [and] Carter Centre [on guinea worm] public-information campaigns about the need to filter drinking water and keep sufferers away from water sources, where they might pass on the infection, have brought new cases down from an estimated 3.5m a year globally in 1986, when eradication efforts started, to 25 last year.

"azithromycin, an antibiotic that works against trachoma (a bacterial infection that can cause blindness)

Note:
(a) About quotation 1.

neglected tropical diseases
https://en.wikipedia.org/wiki/Neglected_tropical_diseases
("Seventeen neglected tropical diseases are prioritized by WHO, though other organizations define NTDs differently")

choi

(c) river blindness
(i) onchocerciasis
https://en.wikipedia.org/wiki/Onchocerciasis
(pathogen: Onchocerca volvulus; is the second most common cause of blindness due to infection, after trachoma; "is spread by the bites of a black fly of the Simulium type [ie, vector]. Usually, many bites are required before infection occurs")
(ii) The genus name Onchocerca: Greek onkos barb [due to its long slender tail, without a hook] + Greek kerkos tail.  Latin verb volvere: to turn, to roll.
(iii) onchocerciasis
https://www.merriam-webster.com/dictionary/onchocerciases
(pronunciation)

(d)
(i) dracunculiasis
https://en.wikipedia.org/wiki/Dracunculiasis
(also called Guinea-worm disease (GWD);  pathogen: Dracunculus medinensis (also known as Guinea worm) )

* dracunculiasis
https://www.merriam-webster.com/dictionary/dracunculiasis
(pronunciation)
(ii) Dracunculus medinensis
https://en.wikipedia.org/wiki/Dracunculus_medinensis
(The common name "guinea worm" is derived from the Guinea region of Western Africa; section 4 Etymology)

(e) azithromycin
https://en.wikipedia.org/wiki/Azithromycin
(chemical structure; section 4 History: discovered by a Croatian pharmaceutical company Pliva in 1980)

choi

(b) Regarding quotation 2.
(i) Song Dj et al, The History of the Elimination of Lymphatic Filariasis in China. Infectious Diseases of Poverty (Dec 2, 2013).
https://idpjournal.biomedcentral ... 1186/2049-9957-2-30

Quote:

"China used to be one of the most heavily epidemic counties [sic; should be countries] for LF in the word.

"Lymphatic filariasis (LF) is an ancient parasitic disease. * * * symptoms similar to the manifestations of LF were recorded in some early Chinese traditional medical books, the earliest being in 600–700 BC.

"Prof Fan Ping-Chin 范秉眞 [footnote 16, which was published in 2003] reviewed that bancroftian filariasis was also prevalent in Yunlin, Jiayi, Tainan, Gaoxiong and Pingtung counties in Taiwan, and Jinmen, Penghu and Matsu Islands, and that the disease in these areas has been controlled effectively." (brackets original)

"The traditional antifilarial drug, diethylcarbamazine (DEC) [was used in China; the medication 'was discovered in 1947'  Wikipedia] * * * In China, there are no animal reservoir hosts for both of W bancrofti and B malayi.

"The biggest advantage of using DEC fortified salt (DEC salt) was that rare and, if any, very mild, side effects occurred * * * [In 2006, China submitted a report to World Health Organization (WHO) indicating the disease had been eliminated in China, though 'a number of chronic cases still exist in China as a result of past infection'].

(A) lymphatic filariasis
https://en.wikipedia.org/wiki/Lymphatic_filariasis
("The worms are spread by the bites of infected mosquitoes. Three types of worms are known to cause the disease: Wuchereria bancrofti, Brugia malayi, and Brugia timori, with Wuchereria bancrofti being the most common. * * * [DEC does] not kill the adult worms but prevent further spread of the disease [so everybody in endemic areas takes DEC, for both treatment and prevention] until the worms die on their own")
(B) The above Wiki page does not mention animal hosts. But see Epidemiology. In Lymphatic filariasis. WHO, undated
www.who.int/lymphatic_filariasis/epidemiology/en/
("Humans are the exclusive host of infection with W bancrofti. Although certain strains of B malayi can also infect some animal species (felines and monkeys)" )
(C) About quotation 1 and 3 of (b)(i). Song's review included a map that showed Taiwan also had the infection even in 1980s, though, as far as I can tell, nobody there knew or saw it, I did a Web search, and it turns out that Taiwan continues having new infections, albeit extremely rare.
* Thomas B Nutman (ed), Lymphatic Filariasis. London: Imperial College Press, 2000, at page 174
https://books.google.com/books?i ... history&f=false
("In Taiwan, lymphoedema of the leg continues to be a public health problem even though transmission of W bancrofti has essentially been interrupted since 1974. This is not surprising, because in many areas, people with long-standing lymphoedema are often not infected with the parasite" (footnotes omitted) )
* 郭韋綺, 象腿症惡化 憂女無人照顧. China Times, Feb 20, 2014
www.chinatimes.com/newspapers/20140220000674-260107
(台灣屏東縣"新埤鄉餉潭村 * * * 35歲方姓婦人 [方美玲] 年輕得下肢淋巴水腫，即俗稱象腿症")

Lymphoedema has many causes. I am unaware whether it has been that this woman suffered from lymphatic filariasis.
(ii) African trypanosomiasis
https://en.wikipedia.org/wiki/African_trypanosomiasis
(also known as sleeping sickness; caused by protozoa of the species Trypanosoma brucei; disease occurs regularly in some regions of sub-Saharan Africa; vector: tsetse fly (that bites) )