1. Haemoparasite-Malaria A Detailed Study www.freelivedoctor.com

5. Geographical Distribution of Malaria Malaria is transmitted by the female anopheles mosquito. Factors which affect mosquito ecology, such as temperature and rainfall, are key determinants of malaria transmission. Mosquitoes breed in hot, humid areas and below altitudes of 2000 meters. Development of the malaria parasite occurs optimally between 25-30 o C and stops below 16 o C. Indigenous malaria has been recorded as far as 64 o N and 32 o S. Malaria has actually increased in sub-Saharan Africa in recent years. The major factor has been the spread of drug-resistant parasites. Other important factors include the persistence of poverty, HIV/AIDS, mosquito resistance to insecticides, weak health services, conflict and population migration. Although previously widespread, today malaria is confined mainly to Africa, Asia and Latin America. About 40% of the world’s population is at risk of malaria. It is endemic in 91 countries, with small pockets of transmission occurring in a further 8 countries. www.freelivedoctor.com

9. The Malaria Parasite Life Cycle Click on the diagram to explore different areas of the life cycle www.freelivedoctor.com

10. The Malaria Parasite Life Cycle 1. Transmission Female anopheles mosquito bites and releases sporozoites into the blood stream. These circulate for about 30 mins and then invade the liver. www.freelivedoctor.com

11. The Malaria Parasite Life Cycle 2. Pre-erythrocytic phase Also called the “tissue” or “hepatic” phase Takes place in hepatocytes. The sporozoites mature into schizonts which rupture to release merozoites. Duration of this phase depends on the species. In P. vivax and P. ovale , the schizont may also differentiate into hypnozoites. These are dormant forms of the parasite which may remain in the liver for several months or years and cause relapse in the human host. www.freelivedoctor.com

12. The Malaria Parasite Life Cycle 3a. Asexual phase (Erythrocytic schizogony) Merozoites invade red blood cells. Here they grow and mature into trophozoites which appear as ring forms. The trophozoites develop into schizonts. The infected red blood cells then rupture to release numerous merozoites from the schizont to infect other red cells. Merozoite release results in fever, chills, rigours and other symptoms of malaria infection. www.freelivedoctor.com

13. The Malaria Parasite Life Cycle 3b. Sexual phase Some merozoites differentiate into male and female gametocytes, the forms of Plasmodia infective to mosquitoes. These are taken up by a mosquito during another blood meal. These fuse to form an ookinette in the gut lumen of the mosquito. The ookinette invades the stomach wall to form the oocyst. This in turn develops and releases sporozoites which migrate to the salivary gland of the mosquito. This mosquito then goes on to infect another human host. www.freelivedoctor.com

16. This is usually seen in older children and adults who have acquired natural immunity to clinical disease as a consequence of living in areas with high malaria endemicity. There are malaria parasites in the peripheral blood but no symptoms. These individuals may be important reservoirs for disease transmission. Some individuals may even develop anti-parasite immunity so that they do not develop parasitaemia following infection. A. Asymptomatic parasitaemia www.freelivedoctor.com

17. B. Simple, uncomplicated malaria Children with malaria waiting to be seen at a malaria clinic in the south western part of Nigeria. Identifying children with severe malaria, and giving them prompt treatment, is a major challenge when large numbers attend clinics. This can occur at any age but it is more likely to be seen in individuals with some degree of immunity to malaria. The affected person, though ill, does not manifest life-threatening disease. Fever is the most constant symptom of malaria. It may occur in paroxysms when lysis of red cells releases merozoites resulting in fever, chills and rigors (uncontrollable shivering). www.freelivedoctor.com

23. Investigations Blood Film Examination Thick and thin blood films (or “smears”) have remained the gold standard for the diagnosis of malaria. The films are stained and examined by microscopy. Thick blood film - Used for detecting malaria: a larger volume of blood is examined allowing detection of even low levels of parasitaemia. Also used for determining parasite density and monitoring the response to treatment. Thin blood film – Gives more information about the parasite morphology and, therefore, is used to identify the particular infecting species of Plasmodium. Show Me Show Me www.freelivedoctor.com

26. Appearance of P. falciparum in thin blood films Ring forms or trophozoites; many red cells infected – some with more than one parasite Gametocytes (sexual stages); After a blood meal, these forms will develop in the mosquito gut http://phil.cdc.gov/phil/quicksearch.asp www.freelivedoctor.com

36. Acute pulmonary oedema, developing shortly after delivery in a woman with severe P. falciparum malaria 6. Acute pulmonary oedema Back This is a grave and usually fatal manifestation of severe falciparum malaria and occurs mainly in adults. Hyperparasitaemia, renal failure and pregnancy are recognised predisposing factors and the condition is commonly associated with hypoglycaemia and metabolic acidosis. www.freelivedoctor.com

37. Features of circulatory collapse (cold/clammy skin, hypotension, peripheral cyanosis, weak/thready pulses) may be seen in patients with severe P. falciparum malaria. “ Algid malaria” is characterised by hypotension, vomiting, diarrhoea, rapid respiration and oliguria. This condition is associated with a poor prognosis. 7. Circulatory collapse, shock, “algid malaria ” Back www.freelivedoctor.com

38. This results from massive intravascular haemolysis. The condition presents with severe pallor, jaundice and passage of dark urine due to haemoglobinuria. It may be associated with acute renal failure. Typical, dark urine of haemoglobinuria on day 0 which has cleared by day 3 8. Haemoglobinuria or “Blackwater Fever” A 3 year old boy with severe anaemia (Hb 3.3 g/dl) and dark urine (shown in the container) Back www.freelivedoctor.com