Milk won the battle against measles long before antibiotics and vaccines – Part 1

Measles was one of the deadliest infectious diseases for children prior to 1915. But in just two decades from 1915 in the UK, measles mortality fell by 90-95 per cent, well before antibiotics in the 1940s and long before the measles vaccine in the 1960s. A similar drop in measles mortality occurred in the USA.

Dr Thomas McKeown noted this astonishing fact in his 1976 book, The Modern Rise of Population. He speculated that nutrition had something to do with it but couldn’t pinpoint the mechanism and wrote: “no completely satisfactory interpretation has been given, or perhaps can be expected, for [this] enormous reduction in mortality”. In 2015, G.D. Shanks et al tried to solve the measles mystery but failed: “[I]t is uncertain how … improvements in nutrition and sanitation would have influenced measles mortality rates”. In 2018, Stephanie Torrez et al attempted to solve the problem but also failed.

1. We need an answer 

Knowing why measles mortality declined sharply without antibiotics and vaccines can potentially lead us to something that is crucially important for health, enabling us to direct our efforts more effectively. The answer that I have found after poring through vast amounts of empirical facts across two centuries, is both simple and astonishing. The answer lies in milk, plus a few secondary factors.

2. Rejecting some options

What are we looking for? We are looking for health-related factors which specifically impact measles, that changed on a grand scale from around 1915.

Was it school closures? No, I have shown earlier that school closures failed repeatedly and were largely abandoned by 1909. Prior to vaccines, almost all children caught measles because it is a highly transmissible disease with asymptomatic spread: “at least ten percent of measles cases occur in a subclinical or unrecognized form” (Donald Henderson, 1967).

Was it the increase in per capita income or improvement in general nutrition? No, because these improve at a slow rate. There’s nothing to suggest rapid change in these factors from 1915.

So, this leaves us with only two candidates: (a) the mass production of clean (Pasteurized) milk, and (b) significant improvements to domestic hygiene.

Of these two, milk is the only factor which ticks all the boxes. First, milk contains Vitamin A, which is proven to save measles lives. Second, the quality and quantity of milk supply dramatically improved from around 1915.

2. Vitamin A saves rats, dogs and children

To understand milk’s role, we need to first understand Vitamin A, which is found in abundance in milk. The story of Vitamin A and milk starts in 1912 when Elmer McCollum and Marguerite Davis “tested rats on three different fats — milk, olive oil, and lard. The milk-fed rats continued to grow and thrive, while the rats receiving olive oil or lard started out well, but then stopped growing, becoming sick and stunted”. Milk was thus hugely protective for rats. Although McCollum was to later claim that he discovered Vitamin A, the actual process of isolating the many vitamins in milk involved many people and took time, leading in 1929 to a Nobel prize for Frederick Gowland Hopkins.

In 1926, Edward Mellanby raised a colony of dogs in a lab, of which two-thirds were experimentally rendered vitamin A-deficient. An epidemic of bronchopneumonia unexpectedly swept through the colony and killed 330 dogs. Analysis showed that most of the dead dogs were from the vitamin A-deficient group, demonstrating the protective effect of Vitamin A in dogs against bacterial pneumonia. Mellanby postulated that Vitamin A might even help reduce child mortality. This was confirmed in 1932 by Joseph B. Ellison whose trials showed that vitamin A treatment reduced children’s measles deaths by 58%. Unfortunately, no one drew the link (which should have been obvious) between increased milk supply and the ongoing rapid decline of measles mortality. Worse, even this study was largely forgotten.

In 1976, Dr. Sommer revived Vitamin A studies in children. His study in Indonesia “revealed that even mild vitamin A deficiency (VAD) dramatically increases childhood mortality rates”. Donald Henderson explained in 1989 that the scientists “administered vitamin A to children in one group of villages; a second group of villages served as a control. The capsules were given once every six months. Death rates among children in the control villages were 50% greater than those which received Vitamin A”. This study has been successfully replicated. A 1999 paper by R D Semba noted that “In the 1980s and early 1990s, several large randomized, double-blind, placebo-controlled clinical trials were conducted in developing countries around the world, and these studies showed that vitamin A supplementation could reduce child mortality by about one-third”.

3. Vitamin A protects from secondary infections

Measles typically doesn’t kill by itself but by attacking the innate immune system, making the patient vulnerable to secondary bacterial infections. Measles also attacks adaptive immunity. A 2019 paper by Michael Mina et al found that measles can eliminate as much as 80 per cent of someone’s previously acquired immunity to other pathogens. The measles virus thus damages our entire immune system.

We have a good picture by now of how Vitamin A strengthens the immune system. A 2011 WHO report noted, “Vitamin A/retinol is involved in the production, growth and differentiation of red cells, lymph cells and antibodies, and epithelial integrity”. In their 1999 paper, F.S. McCullough et al noted that “[a]terations in the epithelial lining of vital organs occur early in deficiency, suggesting a potentially important role for the barrier function”. A 2009 paper by Shaikh Ahmad et al found that “[s]everal aspects of innate immunity are compromised by clinical and subclinical vitamin A deficiency”. The respiratory system weakens the most. A 2018 paper by Lavida R K Brooks et al noted, Streptococcus pneumoniae “has been widely linked to causing respiratory infections in individuals with a weakened immune system”.

In plain English, when a person’s immune system is strong, the epithelium functions well and prevents ever-present bacteria from entering the body. For example, bacteria such as Streptococcus pneumoniae (a Gram-positive bacterium) are found in small numbers even in the throat of healthy persons, without causing pneumonia. But once the immune system is compromised by measles, the epithelial barrier crumbles.

It is not just lungs that are compromised. Even the digestive lining is disrupted, reducing the body’s capacity to absorb Vitamin A. A 2022 paper by Joshua O. Amimo et al showed that “VAD affects immune response and predisposes the host to infection, and infection decreases the intestinal absorption of the VA, thereby contributing to secondary VAD development”. A vicious cycle sets in, leading in some cases to death.

This biological information helps explain the sharp decline in measles mortality when the supply of clean milk increased rapidly in England from around 1910.

END OF ARTICLE