Malaria in Hong Kong

Submitted by Aldi on Fri, 03/03/2023 - 14:44

Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes.

Hong Kong’s long and deadly history of malaria has largely been forgotten.  Because of ignorance of the cause of malaria, (the belief that bad air, or mal aria in medieval Italian, caused it) the loss of life in the past was great, and in years like 1843, ‘inordinate’, causing British troops to retreat from the ‘poisonous miasmas’ of the north shore to their ships at anchor in the harbour, leaving those on land to sickness or death.  One general estimated an entire regiment would be lost every three years at the existing mortality rate.

Attempts to take advantage of the flat shore of the Wong Nai Chung Valley were thwarted by the disease, and the valley of sickness and death and cemeteries (and ghosts), propitiously called Happy Valley, was largely abandoned until 1845 when the swamps and paddy fields of the area were drained to create the racecourse, inadvertently improving the health of the area.

As the population grew, malaria epidemics continued throughout the 19th century, and effective prevention didn’t come until the turn of the 20th century.  A Malaria Bureau was established in 1930 in Caine Lane to tackle the disease and by the 1950s the incidence of disease and the mortality rate were at last decreasing.  Waves of immigrants from China and Vietnam however brought fresh onslaughts of the illness, and even as recently as 1987 there have been fears of malaria resurgence.

The last case of malaria was reported in 1998, and Hong Kong was subsequently pronounced malaria-free by the World Health Organisation.  Outbreaks that occur are usually due to the disease being imported from outside.  Chances of it becoming prevalent again are thought to be ‘unlikely’.

Source:  This SCMP article. 

Malaria is caused by protozoa of the genus Plasmodium. Four species cause disease in humans: 

Plasmodium ovale

Plasmodium vivax (also called tertian malaria)

Plasmodium falciparum (also called malignant tertian malaria)

Plasmodium malariae (also called quartan malaria)

 The second, plasmodium vivax, is prevalent in temperate as well as tropical and subtropical zones, and has the widest geographical range because it can survive at lower temperatures within a mosquito than the other three.

Plasmodium falciparum, the causative agent of malignant malaria, is among the most severe human infectious diseases, with the greatest risk of complications and death.  It is prevalent in the tropics and sub-tropics.

The disease is carried by female anopheline mosquitoes which prefer relatively clean water as their larval habitat.  The male adult anopheline feeds on nectar, while the female adult feeds primarily upon blood. Females of most Anopheles species prefer warm-blooded animals, predominantly mammals. Some species prefer humans, others prefer animals such as cattle.

Human malaria begins when a female anopheline introduces malaria acquired from a previous human blood meal into its current host.  The onset of malaria is a dramatic combination of fevers, chills, and sweats, with periodic paroxysms every 2 or 3 days.

 Due to ignorance, treatments for malaria in medieval Europe included bloodletting, induced vomiting, limb amputation and trepanning (cutting a hole in the skull). The belief that bad air, or mal aria in medieval Italian, caused malaria lingered on in western medicine up to the late 19th century.

In 1820, two French chemists isolated quinine from the cinchona bark and quinine became a treatment of reference for intermittent fever throughout the world. Quinine remains an important and effective treatment for malaria today, despite quinine resistance.

Following the war, chloroquine and DDT emerged as the two principal weapons in WHO’s global eradication malaria campaign, but mosquito strains became resistant to these as well.

Artemisinin was isolated by Chinese scientists in 1972 from Artemisia annua (sweet wormwood).  This  and other artemether-group drugs have been the main line of defence against drug resistant malaria in many parts of South-East Asia. Today, Artemisinin-based combination therapy (ACT) has been shown to improve treatment efficacy and is thought to be a key to containing resistance.  It represents a major breakthrough in the global fight against malaria.

Malaria that recurs following treatment falls into two categories: relapse and recrudescence. Malaria relapse is seen exclusively in P. vivax and P. ovale, and represents a reseeding of the bloodstream by dormant parasites contained in the liver. Recrudescence occurs after a period of remission or quiescence.

In 1934 the missionary Mildred Dibden at the BCMS Foundling Home in Taipo contracted malignant tertian malaria, and very nearly died.  Jill Doggett's account reads, ‘In the swampy marshes around Tolo Harbour and in the vicinity of Taipo, clumps of yellow bamboo cane were favourite breeding places for the tiny wrigglers that later grew into the anopheles mosquito, a malaria-carrying parasite that has accounted for so many lives lost both in the history of Hong Kong and in many lands around the world . . . Taipo in the 1930s claimed many malaria victims.’ 

In 1937 the BCMS Home was moved back to Kowloon as it was thought to be healthier there.

Sources: National Library of Medicine

 

According to Geoffrey Emerson (Hong Kong Internment 1942-45) malaria was the main medical problem after malnutrition.  Stanley peninsula contains a number of graves of  Europeans who died of malaria there in the 19th century.  By 1941 the peninsula was practically free of the disease, but constant anti-malarial measures were necessary to keep it that way. 

In Stanley Camp breeding grounds were eliminated by grass cutting, drainage and filling, but requests for work parties to go outside the camp were ignored by the Japanese until incidence increased and they themselves were affected in July 1943.  From that time on, working parties were allowed outside the Camp, but not into Stanley Village.  The only treatment for malaria was quinine, but that was always hard to get hold of.  Many who had malaria suffered relapses.  In all there were 682 cases, but none serious enough to cause death.

It is nevertheless interesting that Hong Kong may have been thought of as relatively “non-malarious” and "healthy" by comparison to parts of mainland China in the 1880s. The missionary, the Reverend John Browne Ost forwarded a letter to his CMS superiors, dated 9 November 1880 from one Dr. R.A. O’Brien advising against the Rev. Ost being posted to any “malarious” district after frequently falling ill in Ningpo. He writes that “The Rev. Mr. Ost came to Hong Kong suffering from a severe form of malarious fever.” Ost’s own letter dated 10 November 1880 to his superior at Church Missionary House in London reads as follows:

You may have heard of the very severe and prolonged attacks of fever and ague I had at Ningpo during the latter part of September and early part of October. At first the fever took the form of congestion of the brain rendering me for some time quite delirious (…) This later attack I had at Chinghai – a small town at the entrance of Ningpo River – where I had gone by the doctor’s advice to try to shake off the fever and get some sea air. On 6th October I started for Hong Kong and though I had severe attacks on the voyage down, a few days after arriving I soon began to recover and am now thank God quite free from the attacks and gaining strength.

The Reverend Ost duly obtained a permanent post in Hong Kong until he was recalled to London in1891. Other CMS letters from John Ost and his wife in Hong Kong are included in Patricia P. K. Chiu’s chapter in ed. Philip L. Wickeri, Christian Encounters with Chinese Culture, HKU, 2015.

Pamela Tyrer in her account Stolen Childhood says that in the summer of 1944 'half of Stanley Camp was suffering from malaria', due to the paddy fields being a fertile breeding ground for mosquitoes, and Dr Cater decided something must be done.  The Japanese were persuaded to supply the internees with Paris Green, a pesticide, to spray on the paddy fields. Two of them would go out with two guards, two sprays and a bag of Paris Green.