Immunisation used for offensive and defensive purposes during the Second World War.

The best defence against natural or intentional biological agents during armed conflict is usually immunisation, as with typhoid fever, but exceptional circumstances are informative. A large iatrogenic epidemic of hepatitis B occurred in 1942 due to contaminated lots of yellow fever (YF) vaccine used in the US military, even though there was no natural risk of infection. YF vaccine was intended to protect against Japanese Army's use of YF as a biowarfare agent, which did not eventuate. Salmonella typhi was used to infect German soldiers in a Paris café during Christmas 1941 in the knowledge that the café staff but not the soldiers were likely to be immunised against typhoid fever. German Army use of the Weil-Felix reaction to eliminate civilians likely to be typhus infected was subverted by Polish medical officers. They immunised civilians with locally produced Proteus antigens to create false-positive Weil-Felix reactions in order to exempt men from forced labour schemes. Immunisation against biowarfare agents has a mixed record, indicating that vaccines rarely cover well for intelligence gaps.

Liberty ship sinking disrupts military medical mobilisation in 1942.

Medical mobilisation is vital to support tropical campaigns where many disease casualties are expected. Much of the medical supplies and equipment for nine station and three general hospitals that were being placed in Australia were aboard the Liberty Ship SS Rufus King when it went aground off Moreton Island on 7 July 1942. A concerted salvage operation rescued 85% of the stores from the freighter that had broken in half on the Amity sandbar. This emergency effort allowed medical support to New Guinea to proceed without delays due to medical supplies that were nearly lost at sea.

Reintroduced malaria in Queensland, Australia during the Second World War.

A malaria epidemic arose in 1942 in Cairns, which was the evacuation point from the Japanese offensive in New Guinea. Health authorities made great efforts to suppress parasites in transiting soldiers and to position them south of 19°S latitude away from most vectors. Queensland experienced some scattered locally transmitted epidemics in 1943-1944 but by 1945 malaria transmission had largely been eliminated.

Decreased Mortality of falciparum Malaria in Anemic Prisoners of War?

Modern clinical trials have suggested that anemia protects against malaria mortality. Military records of the Second World War in Asia were examined to see if there was support for this hypothesis. When relatively well-nourished Imperial Japanese Navy sailors captured on Nauru (n = 799) were imprisoned on the Fauro Islands, 26% died from falciparum malaria. Similarly treated but very malnourished colocated Imperial Army soldiers experienced low stable malaria mortality. One-fifth of previously healthy Australian Army soldiers (n = 252) retreating from New Britain died largely because of malaria in April 1942. Malnourished prisoners of war, who were as a group very anemic, both Australian Army soldiers in Thailand and Japanese Army soldiers in Papua New Guinea, had high malaria rates but very low (< 3%) mortality rates. Malaria immunity does not adequately explain this dichotomy, suggesting that severe nutritional deprivation may be protective against malaria mortality possibly because of iron-deficiency anemia.

Epidemiological Isolation as an Infection Mortality Risk Factor in U.S. Soldiers from Late Nineteenth to Early Twentieth Centuries.

It remains uncertain why most infectious disease mortalities disappeared before modern medical interventions. Historical epidemiology using prospectively collected U.S. Army data from the Civil War (1860-1861), Spanish-American War (1898-1899), and First World War (1917-1918) suggests that epidemiological isolation was a major mortality risk factor for soldiers. Morbidity and mortality due to common infections decreased progressively from 1860 to 1918, except for influenza during the 1918 pandemic. Adult measles or mumps infections are indicative of isolated rural populations and correlated with disease mortality by U.S. state. Experiencing infections before adulthood may equip the immune system to better resist infections and decrease mortality rates.

Malaria-Associated Mortality in Australian and British Prisoners of War on the Thai-Burma Railway 1943-1944.

During the building of the Thai-Burma railway in 1943 Australian and British prisoners of war died at high rates from tropical infections and nutritional deficiencies. Mortality records from "F" Force (n = 7,000) showed nearly half (44%) of the soldiers perished in a single year, yet only 4% of these deaths were primarily attributed to malaria, with another 7% where malaria was listed as a major contributing cause. Case fatality rates were < 1%, with nearly all soldiers chronically infected with Plasmodium vivax > Plasmodium falciparum. Separate labor camp point prevalence malaria rates by microscopy ranged from 28% to 69% (median 54%) despite intermittent quinine suppression. During complex public health emergencies, malaria mortality may be disguised by its combination with other common infections and nutritional deficiencies.

Tolerance May Be More Appropriate Than Immunity When Describing Chronic Malaria Infections.

Adults who have not grown up in a malaria-endemic area may experience severe malaria soon after entering a malarious area. Such mortality is usually limited to a short period of time (months), after which they are thought to be "immune." Such anti-disease immunity may be more accurately considered as tolerance. Malaria rates of British soldiers during the Second World War reflected their time with suppressed infections and the transmission levels. Black workers from non-endemic areas on the Panama Canal experienced higher initial mortality and infection rates than co-located white workers for Plasmodium falciparum, whereas the known genetic resistance of blacks to Plasmodium vivax reversed these rates. The ethnic differences observed in malaria rates may have more to do with acquired tolerance than genetic resistance. Long-term (years) sub-patent infections may maintain host tolerance, and elimination of malaria infections may place these adults at subsequent risk of severe malaria.

Mass drug administration for the control and elimination of Plasmodium vivax malaria: an ecological study from Jiangsu province, China.

BACKGROUND: Recent progress in malaria control has caused renewed interest in mass drug administration (MDA) as a potential elimination strategy but the evidence base is limited. China has extensive experience with MDA, but it is not well documented. METHODS: An ecological study was conducted to describe the use of MDA for the control and elimination of Plasmodium vivax in Jiangsu Province and explore the association between MDA and malaria incidence. Two periods were focused on: 1973 to 1983 when malaria burden was high and MDA administered to highly endemic counties province-wide, and 2000 to 2009, when malaria burden was low and a focal approach was used in two counties. All available data about the strategies implemented, MDA coverage, co-interventions, incidence, and adverse events were collected and described. Joinpoint analysis was used to describe trends in incidence and the relationship between MDA coverage and incidence was explored in negative binomial regression models. RESULTS: From 1973 to 1983, MDA with pyrimethamine and primaquine was used on a large scale, with up to 30 million people in target counties covered in a peak year (50% of the total population). Joinpoint analyses identified declines in annual incidence, -56.7% (95% CI -75.5 to -23.7%) from 1973-1976 and -12.4% (95% CI -24.7 to 2.0%) from 1976-1983. Population average negative binomial models identified a relationship between higher total population MDA coverage and lower monthly incidence from 1973-1976, IRR 0.98 (95% CI 0.97 to 1.00), while co-interventions, rainfall and GDP were not associated. From 2000-2009, incidence in two counties declined (annual change -43.7 to -14.0%) during a time when focal MDA using chloroquine and primaquine was targeted to villages and/or individuals residing near passively detected index cases (median 0.04% of total population). Although safety data were not collected systematically, there were rare reports of serious but non-fatal events. CONCLUSIONS: In Jiangsu Province, China, large-scale MDA was implemented and associated with declines in high P. vivax malaria transmission; a more recent focal approach may have contributed to interruption of transmission. MDA should be considered a potential key strategy for malaria control and elimination.