Natural history of malaria

malaria epideological triad,clinical feaATURES

1. MALARIA

2. INTRODUCTION - MALA - BAD ARIA – AIR In ancient Italy , people associated this with bad air . Hence ,the name MALARIA. It’s a communicable disease caused by protozoal parasite , of the genius plasmodium transmitted from person to person by the bite of infected female Anopheles mosquito. The mortality is not high but it produces incapacitation affecting the human resources of the country which ultimately affects the progress of the nation, socially & economically.

3. HISTORY - Hippocrates in 5 th century BC was the first person to describe features of malaria. Charak And Sushruta also gave the description of the disease & associated the disease with the bites of mosquitoes. 1880-Laveron, a French army surgeon, discovered malarial parasites in human RBCs & got Nobel prize. 1894-Mason hypothesized that mosquitoes transmit the disease.

4. 1897-Ronald Ross confirmed the same & studied the development of parasite in the body of the female anopheline mosquito 1898-3 Italian scientist namely Bignami , B astianelli & Grassi demonstrated the sporozoites in the salivary glands of Anophelin mosquitoes. 1939- P aul M uller discovered insecticidal property of DDT, which opened a new avenue in control of malaria 1953- Govt. Of India launched National malaria Control Program(NMCP)

5. 1958-NMCP was converted into National malaria Eradication Program(NMEP) 197-NMEP was revised and upgraded & was called as Modified Plan Of Operation Of malaria Control(MPO) 1995-accelerated malaria action program was taken up in high risk areas. 1999-national Program was renamed as “National Anti Malaria Program” Since 2003-04, the National program against malaria is included under national Vector Borne Disease Control Program(NVBDCP)

6. M AGNITUDE - Malaria is a global problem, about 100 countries are malarious According to the latest estimates, there were about 198 million (124-283 million) cases of malaria in the year 2013 and an estimated 584,000 deaths (367,000-755,000). Malaria mortality rates have fallen by 4 7 per cent globally since year 2000, and by 54 per cent in the WHO African Region. Most deaths occur among children living in Africa, where a child dies every minute from malaria (lA

7. INDIA Malaria continues to pose a major public health threat in India, particularly due to Plasmodium falciparum which is prone to complications. In India about 21.98 per cent population lives in malaria high transmission areas. ( More than 1 case/1000 population) areas and about 67 per cent in low transmission (0-1 case/1000 population) areas (2). About 92 per cent of malaria cases and 97 per cent of deaths due to malaria is reported from North-eastern states .

8. AGENT FACTOR- Malaria is caused by four species of protozoal parasite of genus “Plasmodium”. They are PL. vivax PL. falciparum PL. malarie PL. ovale PL. vivax is responsible for about 70% of the case PL. falciparum for 25-30% 4-8% due to mixed infection PL. malarie for less than 1% infection in India.

9. LIFE HISTORY - The malaria parasite undergoes 2 cycles of development the human cycle (asexual cycle) and the mosquito cycle (sexual cycle). Man is the intermediate host and mosquito the definitive host. human being= sporozoites- hepatic phase- erythrocytic phase- gamates mosquito- gamets- ookinet- ocyst- sporozoites which are stored in salivary gland of mosquito. infective form.

10. RESERVOIR OF INFECTION- There is only human resevoir & no animal reservior except chimpanzees in Africa, which carry PL. malarie . A reservoir may be a case or carrier. A carrier is one who is having gametocytes circulating in the blood. Children are more likely to be gametocyte carriers than adults. T he criteria to call a person as malaria carrier are: • He/she should have both the sexes of the gametocytes in the blood • The gametocytes must be matured • They must be viable • They must be present in sufficient numbers (density) (at least 12 per Cu mm of blood).

11. HOST FACTORS - AGE INCIDENCE- No age is bar form malaria. Newborns are resistant to Pl. falciparum because of high concentration of fetal hemoglobin. Young children are high risk group. SEX- Men are more prone because of outdoor life and less clothed than women. PREGNANCY- Pregnancy increase the risk & severity of malaria. It may result in abortion or still birth or premature delivery. Occupation- It is more among rural people, because of agricultural occupation.

12. HOUSING: Housing plays an important role in the epidemiology of malaria. The ill-ventilated and ill-lighted houses provide ideal indoor resting places for mosquitoes. Malaria is acquired in most instances by mosquito-bites within the houses. POPULATION MOBILITY : People migrate for one reason or other from one country to another or from one part of a country to another.Some of them may import malaria parasites in their blood and reintroduce malaria into areas where malaria has been controlled or eliminated.

13. HUMAN HABITS : Habits such as sleeping out of doors, nomadism, refusal to accept spraying of houses, replastering of walls after spraying and not using measures of personal protection (e.g. bed nets) influence man-vector contact, and obviously the choice of control measures. IMMUNITY-Active immunity is species-specific, that is, immunity against one strain does not protect against another. People living in endemic areas exposed continually to malaria develop considerable degree of resistance to clinical disease

14. PRE-DISPOSING FACTOR- Poor- standard of housing with ill- lighting & ill – ventilation Human activities like *industrialization * urbanisation *irrigation *agricultural activities *deforestation Therefore malaria due to such is called “Man – Made ” Malaria.

15. ENVIRONMENTAL FACTOR - SEASON-Incidence high between July to November. Atmospheric temp.- Favorable temp. for the development of parasite is between 20*-30* C. Rainfall- it provides breeding places for mosquitoes. Altitude- Altitude above 2500 meters is unfavorable so, malaria is rare in Nepal. MAN-MADE MALARIA: Burrow pits, garden pools, irrigation channels and engineering projects like construction of hydroelectric dams, roads, bridges have led to the breeding of mosquitoes and an increase in malaria. Malaria consequent on such human undertakings is called "man-made malaria".

16. Vectors of malaria- Female anophelin are chief vectors. Others are- CULCIFACIES, FLUVIATILIS, STEPENIS, MINIMUS, PHILLIPPINENISIS, SUDAICUS, MACULATUS Breeding habits: Anopheline female mosquito breeds in fresh water as in ponds, cisterns, wells, over-head tanks, pools, etc. anti-larval measures have to be carried out only in such breeding places.

17. Feeding habits: Anopheline female mosquitoes feed on human blood (anthrophilic). Blood meal is a must for laying eggs. Male mosquitoes do not transmit the disease because they do not bite. They feed on plant and fruit juice. Female mosquitoes bite during night times . Resting habits : Most of these vectors rest indoors, after blood meal (endophily). Few rest outdoors (exophily). Therefore anti-adult measures are carried out indoors. Density : Mosquitoes should be present in adequate density (above the critical level) for active transmission of the disease. T his varies from species to species.

18. MODE OF TRANSMISSION - Malaria is transmitted usually form person to person by the bite of infected female anophelin mosquito. It is also transmitted accidentally through contaminated syringes & needles. Vertical transmission form infected pregnant mothers to the fetus can occur but very rare.

19. INCUBATION PERIOD- It is the period between the bite of the infected mosquito and the onset of first symptom i.e. fever. The period varies as follows- *PL. vivax-14 days *PL. falciparum-12 days *PL. malariae-28days *PL. Ovale - 17 days

20. CLINICAL FEATURES - Benign Tertian Malaria ( Vivax Malaria) There are three stages- (1) Cold Stage- *Sudden onset of fever with rigors *Sensation of extreme cold *Teeth chatter *Desire to cover with several blankets *Severe headache * Vomiting (2) Hot Stage- *High fever 103 *- 104* F *Burning hot sensation, remove blanket & his/her clothes.

21. *Headache This stages last for 2-6 hours. (3) Sweating Stage-(Stage of diaphoretica) * Fever comes down associated with profuse sweating. *Followed by deep sleep due to exhaustion *this stage lasts for 2-4 hours. In vivax malaria, fever reappears every third day. Rupture of RBC & release of merozoites in associate with rigors. Repeated episodes result in splenomegaly & secondary anaemia .

22. Malignant Tertian Malaria ( Falciparum Malaria)- *Gradual rise of temp, increase daily becomes high & almost continuous. *Cold, hot & sweating stage rarely occur. *Vomiting & headache persist. COMPLICATION - Cerebral malaria - *High fever *Death *Convulsion *Coma *Paralysis *Delirium *Stupor

23. Black Water Fever *Fever *Black- coloured urine due to hemolysis of RBCs & hemoglobinuria. Algid Malaria *Features of shock Septicemic Malaria *Features of septicemia & circulatory failure Quartun Malaria : This is caused by Pl. malariae. Fever appears once in 4 days. d. Ovale Malaria : This is cause by Pl. ovale, common only in Africa.

24. Thank you