Type and parasite
Visceral L. donovani (including infantile)
Mucocutaneous L. braziliensis L. guyanensis
Central Asia China
India, Bangladesh Sudan, Chad
Central and South America
Central and South America
Cutaneous (New World)
L. mexicana Mexico, Belize, Guatemala
Amazon Basin Peru
Cutaneous (Old World)
Mediterranean Southwest Asia
L. major L. tropica
Central Asia India
Phlebotamus peniciosus, P. ariasi, P. major syriacus, P. longicuspis
P. major syriacus, P. smirnovi, P. longiductus P. chinensis
P. argentipes, P. papatasi P. orientalis, P. martini
L. wellcomi, L. L.trapidoi umbratilis,
L. peruensis, L. verrucarum
P. papatasi P. papatasi, P. P. papatasi P. sergenti P. duboscqi P. longpipes P. pedifer sergenti
Dogs, jackals, foxes
Wild rodents and carnivores
Rodents and forest animals
Forest rodents Forest rodents Dogs
Rodents, dogs, gerbils Dogs, rodents Rodents, gerbils Dogs
The global distribution of cutaneous and visceral leishmaniasis. H, Cutaneous;
A range of reservoirs is found in this complex of diseases. In Central Asia, cutaneous leishmaniasis is a zoonosis, the gerbil being the main reservoir. In India, there is a domestic reservoir, mainly dogs, but direct human-to-human transmission also occurs. These are summarized in Table 15.6.
Transmission can also take place directly through needles and other instruments contaminated with blood of an infected person. Sadly, this is also the method by which HIV is transmitted in many developing countries.
Incubation period 2 weeks to 6 months, but can be years.
Period of communicability The untreated case can remain infectious to sandflies for up to 2 years.
Occurrence and distribution Leishmaniasis is found in Central and South America, north of the equator in Africa , in the Mediterranean, Southwest, Central and South Asia and part of China as shown in Fig. 15.22 and Table 15.6. Population movements, both of persons from endemic rural areas into towns and large man-made projects, such as dams in endemic foci, have brought an increasing number of people into contact with leishmaniasis. Also, the spread of HIV infection has made what was largely a curable condition into a persistent source of parasites for the vector sandfly and as a result, a more serious disease.
Immunity develops following infection with the parasite, but there is little cross-immunity. L. tropica has been used for a long time as an inoculum to induce a sore on a hidden part of the body so as to prevent a more disfiguring lesion developing on the face. L. major will protect against L. tropica as well as L. major lesions, and suspensions of living organisms have been prepared for this purpose. There is no cross-immunity with kala-azar and the other species of Leishmania, but an attack of kala-azar will protect against developing kala-azar in any other part of the world.
Control and prevention Cases of the disease are normally sporadic, so should be treated to prevent flies from becoming infected. Repellents and personal protection adequately protect the individual from being bitten. Sandfly nets can be used, but a more effective solution is ITMN or LLIN (see Malaria above). Because of the fragile nature of the vector, it is easily attacked with insecticides, either with a residual house spray if the vector comes indoors, or by insecticide powder blown into mammal burrows, ant hills and similar micro-habitats. A long-term solution is to alter the micro-environment, such as by the destruction of termite hills and killing of rodents. Proper control of domestic animals, especially dogs, can be effective where they are important reservoirs. Low-dose inocula and attenuated vaccines have been developed to minimize the severity of disease in some endemic areas. The concomitant problem of HIV infection has added to the seriousness of dual infection, so a simultaneous programme of STI control is required and information produced on how to avoid both diseases.
Treatment is with sodium stibogluconate or meglumine antimonate, but pentamidine or amphotericin B may be required in cases that do not respond, especially mucocuta-neous leishmaniasis. Because of the toxicity of the preparations, treatment should be undertaken in hospital. Miltefosine maybe useful in the treatment of visceral leishman-iasis.
Surveillance Outbreaks should be reported to neighbouring countries so that they can take control measures in border areas. Patients with HIV infection should be examined for reactivated leishmaniasis.
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