Leishmaniasis, Biology

Leishmaniasis


Leishmaniasis is a group of disease caused by protozoa of the group Leishmania, and are transmitted to man by the bite of female sandfly (Phlebotomus). Three types of leishmaniasis are recognized, viz. visceral leishmaniasis ( kala-azar), cutaneous leishmaniasis (oriental sore) and mucocutaneous leishmaniasis (espundia).


Three specific agents, viz., Leishmania donovani, the causative agent of Kala-azar,L. tropica, the causative agent of oriental sore and L. braziliensis, the causative agent of mucocutaneous leishmaniasis, are responsible for different forms of leishmaniasis. But this distinction is not absolute, visceral forms of may produce cutaneous lesions and cutaneous form may produce visceral lesions.


Epidemiology: Kala-azar is widely distributed throughout the world including India. Oriental sore occurs in dry, semi-dry rural areas of the Central Asia, the Middle East, the North and West Africa. Mucocutaneous form is native to Brazil only. Kala-azar was a public problem in India in 1940s and was endemic in Assam, West Bengal, Bihar, Uttar Pradesh and to a lesser extent in Tamil Nadu and Orissa. As a result of the massive insecticide spraying for malaria eradication, kala-azar has almost disappeared.


The majority of the leishmaniases are zoonoses involving wild or domestic mammals (rodents, dogs, foxes and marsupials). Indian kala-azar is a non-zoonotic infection with man as the sole reservoir of the disease (anthroponosis).
Leishmaniases are transmitted by the bite of the female sandfly (Phlebotomus). After an infective blood meal, the sandfly becomes infective in 6 to 9 days (extrinsic period). Kala-azar occurs in all age groups including infants. Kala-azar is mostly confined to the plains; it does not occur in altitude over 2,000 feet. There is high prevalence of the disease during and after rains with a humidity above 70 %.


Clinical features:

The incubation period in man is usually 1 to 4 months.
 
Kala-azar: Onset of the disease is sudden or insidious. Irregular malaise, headache, and fever with progressive enlargement of spleen (spleenomegaly), and liver (hepatomegaly) are the classical clinical signs. The double rise of temperature in 24 hours is a characteristic feature. The disease is generally fatal if it is not treated.


Cutaneous leishmaniasis: The disease may be mistaken for leprosy. The agent is restricted to skin. The disease is characterized by ulcers in the legs, arms or face – the parts exposed to the sandfly.
Mucocutaneous leishmaniasis: The agent involves the skin and mucosa. Ulcers appear around the margins of the mouth and nose.
Laboratory diagnosis: Following diagnostic methods are used for diagnosis of the disease.
Demonstration of parasite: Demonstration by microscopical examination of bone
marrow, spleen or liver biopsy for the presence of Leishmania bodies. Culture of bone morrow is more sensitive a test than examination by smear.


Demonstration   of   antibodies: 
  Complement   fixation   test ,indirect immunofluorescence test and enzyme-linked immunosorbent assay are used for diagnosis of leishmaniasis antibodies. Leishmania or Montenegro skin test (allergic test) indicates delayed hypersensitivity to leishmanial antigens. The test is less specific than the serological tests.


Control and prevention: The basic control measures include:
1.  Control of dogs and rodents.
2.  Application of suitable insecticides to kill the sandfly.
3.  Immunoprophylaxis with attenuated strains would be an alternative approach to control the infection.

Posted Date: 9/20/2012 3:19:40 AM | Location : United States







Related Discussions:- Leishmaniasis, Assignment Help, Ask Question on Leishmaniasis, Get Answer, Expert's Help, Leishmaniasis Discussions

Write discussion on Leishmaniasis
Your posts are moderated
Related Questions
Is the biological species concept subjective or objective? How about the phylogenetic species concept or is it subjective or objective?

Q. What is the group of the phylum Chordata that first colonized the terrestrial environment? From which habitat did they come? Partially aquatic partially terrestrial animals,

What is Hemocoel? Explain in detail. Principle body cavity in molluscs and arthropods, remnant of the blastocoel. It forms part of open circulatory system found in these animal

Ecosystem as a Unit of Nature An ecosystem can be visualised as a functional unit of nature representing complex interactions between living and non-living components. Th

Q. Which chemical elements are involved to form most of living biological matter? Ans The chemical elements that form most of the molecules of living beings are carbon (C)

Q. What is the lasting form in the gametophyte, pteridophytes or the sporophyte? How can it be compared to bryophytes? The lasting form in pteridophytes is the diploid (2n) spo

Explain the term Phytates? We are familiar with phytates as an inhibitor of mineral absorption (calcium, iron etc.) especially in the vegetarian diets that are cereal-based. Th

Locomotion Continuous formation of new  pseudopodia keeps amoeba in constant locomotion .This is called  amoeboid  movement .It  occurs  in many  other  protozoans , in  amoebo

THE RAPEUTIC NURSE: Development of  therapeutic  nurse patient  relationship is the basic requirement  of nursing. A helping relationship  in nursing may be explained as an in

Explain radiation sterilization Various studies have been conducted which show the effect of processing on vitamins especially, thiamine. In one study, which compared the effec