23-05-2012, 11:57 AM
A VECTOR BORNE DISEASE
MALARIA ( A VECTOR BORNE DISEASE).pptx (Size: 4.43 MB / Downloads: 133)
Background
looking at the history malaria has infected humans for over 50,000 years, and ''Plasmodium'' may have been a human pathogen for the entire history of the species.
Close relatives of the human malaria parasites remain common in chimpanzees.
References to the unique periodic fevers of malaria are found throughout recorded history, beginning in 2700 BC in China
It has been estimated that in 1950s Annual incidence of malaria was 250 million cases with fatality of 2.5 million every year.
After 1st world war 60,000 were dead in Soviet Union, In 1934-35 ,82,000 death in epidemic of malaria in Sri lanka.In 1958 an epidemic of malaria in Ethiopia caused 1,50,000 deaths. In 1963 epidemic of malaria in Haiti, An in 1967 resurgence of malaria in Sri Lanka.
and the disease was formerly called ''ague'' or ''marsh fever'' due to its association with swamps and marshland.
Malaria was once common in most of Europe and North America, where it is no longer endemic, though imported cases do occur
In Nepal, Approximately 24 million people are at risk of malaria, with 64 of the 75 districts endemic and 13 districts bordering India (Uttar Pradesh and Bihar states)most affected. Transmission occurs mainly during April–September and almost 20% of cases are caused by P. falciparum.
Most of the population at risk is not examined annually but in 2007 the blood examination rate for suspected malaria cases reached 100%. Confi rmed cases decreased from 7763 during 2000–2005 to 3335 in 2009 (57% decline). Malaria admissions decreased from 1414 to 129 (91% decline) during same period, and malaria deaths fell to 8 in 2009 from a peak of 42 in 2006.
These data reflect an overall reduction of the malaria burden, although it is unclear to what extent the gains can be attributed directly to the interventions.
Period of communicability:
In vivax,ovale:4-5 days after the appearance of asexual parasites. up to 1-3 years(Hypnozoints)
In falciparum:10-12 days after the appearance of asexual parasites. Up to <1 year
P.malariae: up to 3 years
2.Host Factor: main variables of human element that have an influence on malaria epidemiology includes:
Immunity:
Active immunity is species specific i.e. immunity against one strain does not protect against another.
Innate immunity is present in some people like person of African origin to some type of malaria than other races.
Protective action of G6PD normally present in RBC.
People living in endemic area might develop considerable degree of resistance to clinical disease. But it declines as they leave the area gradually, So non endemic areas suffer most from the disease.
Vector:
Human malaria can be transmitted only by anopheline mosquitoes.
There are 400 species of Anopheles in the world ,only 60 are of importance.
Mosquito fauna surveys have revealed 42 anopheles species in Nepal.
Acc to zoological classification,anopheline belongs to order diptera,sub family-culicinae & tribe Anopheline.
The following anopheline were responsible for malaria transmission in Nepal:
(1) Anopheles minimus (not reported since its elimination during the
eradication phase)
(2) Anopheles fluviatilis (primary malaria vector)
(3) Anopheles maculatus (vector of secondary importance)
(4) Anopheles annularis (vector of secondary importance)
(5) Anopheles culicifacies (suspected vector in terai region).