Although inbreeding in animals is detrimental, in many human population second cousin marriages are common and even preferred. Such populations often suffer increased rates of heritable diseases, but the impact on infectious diseases remains unclear.

We show that consanguinity does increase the risk of infection by tuberculosis and hepatitis, suggesting that these and perhaps other similar diseases will spread more easily in some populations than others. At the same time it should be possible to identify individuals who are most at risk.

We found no effect in leprosy or for hepatitis in a population where consanguineous marriages are more or less absent.

Royal Society Journal Biology Letters

Proceedings B is the Royal Society's flagship biological research journal, dedicated to the rapid publication and broad dissemination of high-quality research papers, reviews and comment and reply papers. The scope of the journal is diverse and is especially strong in organismal biology.

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