Leishmaniasis is caused by a protozoa parasite from over 20 Leishmania species. Over 90 sandfly species are known to transmit Leishmania parasites. There are 3 main forms of the disease:

Lassa fever is an acute viral haemorrhagic illness caused by Lassa virus, a member of the arenavirus family of viruses. Humans usually become infected through aerosol or direct contact with excreta of infected rodents. 

Lassa fever can also be spread between humans through direct contact with the blood, pharyngeal secretions, urine, faeces or other body secretions of an infected person. Person-to-person transmission of Lassa fever has occurred in health care settings after exposure to blood and secretions of infected patients.