the parasitic infection ni paediatrics.pptx

parasitic infections important in clinical practices

1. PARASITIC INFECTION

2. MALARIA

3. EPIDEMIOLOGY AGENT : 4 species of protozoal parasite belonging to the genus Plasmodium; P.vivax (30%) P.falciparum (60%) P.malariae P.ovale 2 cycles of development – Asexual cycle in humans & Sexual cycle in mosquitoes Man – intermediate host Mosquito – definitive host

4. Differences between the Plasmodium species : 1. No. of merozoites released from each schizont Pf >>> other species 2. Relapse 3. Duration of erythrocytic phase 4. Affinity for RBC’s Pv , Po - Young RBC’s Pm - Old RBC’s Pf - RBC’s of all ages 5. Gametocyte production Pv - soon after asexual erythrocytic stage begins Pf - after many cycles ; atleast 10 days after appearance of clinical disease

5. Hepatic phase : In case of Pf , the intrahepatic schizonts rupture almost simultaneously & there is no persistent tissue phase. But in Pv , Po, Pm they do not burst at same time & some hepatic forms persists and remain dormant in the hepatocytes – “ Relapses ” Erythrocytic schizogony 48 hr in Pf, Pv, Po 72 hr in Pm gametocytes

6. RESERVOIR OF INFECTION: No animal reservoirs But recently human infections with monkey malaria parasite P.knowlesi has been found in forest regions of SE Asia. A human reservoir is one who harbours the sexual forms ( gametocytes ) of the parasite Criteria for a man to serve as malaria carrier are ; Person should have both the sexes of gametocytes in the blood Gametocytes must be mature They must be viable Must be present in sufficient density to infect mosquitoes ( atleast 12 per cubic mm of blood)

7. ENVIRONMENT Season : Maximum during July – November Temperature : Affects life cycle of the parasite inside vector; Optimum range is 20-30 deg.C Humidity : A relative humidity of 60% is considered necessary for the mosquito to live its normal life span. Rainfall : Provides mosquito breeding places; increases atmospheric humidity Altitude : 2000-2500 metres , beyond which anophelines are not found

8. Mode of transmission : Vector borne Direct - blood transfusion; drug addicts Incubation period : It is the length of time between bite of infective mosquito (inoculation of sporozoites ) & the appearance of clinical signs (fever) Pf - 12 days Pv - 14 days Po - 17 days Pm - 28 days

9. Cold Stage Hot Stage Sweating Stage Complications: Cerebral malaria Anemia Dehydration Acute renal failure Liver damage GI symptoms Black water fever

10. Features of Severe Malaria Impaired consciousness / coma Repeated generalized convulsions Renal failure ( S.creatinine >3mg/dl ) Jaundice ( S.bilirubin >3mg/dl) Severe anaemia ( Hb < 5g/dl) Pulmonary oedema / ARDS Hypoglycemia ( Plasma glucose < 40mg/dl) Metabolic acidosis Circulatory collapse or shock - “ Algid malaria ” Abnormal bleeding / DIC Haemoglobinuria Hyperthermia ( Temperature >104 F) Hyperparasitaemia

11. DIAGNOSIS

12. Microscopy Microscopy of stained thick and thin blood smears remains the gold standard for confirmation of diagnosis of malaria. Sensitivity is high Helps to quantify the parasite load Thick smear – shows whether the slide is positive for MP or not Thin smear – shows the species of the MP & the stages of development in red cells

13. Rapid diagnostic tests (RDTs) RDTs are based on the detection of circulating parasite antigens Several types of RDTs are available Cassettes, cards or dip sticks Some of them can only detect P.falciparum , while others can detect other parasite species also The NVBDCP has recently rolled out bivalent RDTs (for detecting P.falciparum and P.vivax ) for use in the public health sector.

14. Types : I. Histidine rich protein 2 ( HRP2 ) - water soluble protein produced only by P.falciparum II. Plasmodium lactate dehydronase ( pLDH ) - currently used in products that include P.falciparum specific, pan specific and P. vivax specific pLDH . III. Aldolase (pan-specific)

15. PRINCIPLE: Immunochromatography Patient’s blood + lyzing agent- ruptures RBC -Releases > parasite protein Labelled antibody - Binds with the target protein (antigen) Passes along the nitro cellulose strip: Capillary action Passes over the test and control bands Free, labelled antibody captures parasite antigen if present Captured by test band antibody- Purple band

16. PRINCIPLE

17. MICROSCOPY RDTs Can also show parasite density Give only positive or negative result Gives negative result as soon as the parasite is cleared from patients blood Detects persisting antigens after parasite clearance Upto 5-6 days : pLDH Upto 1-5 weeks : HRP2 Inexpensive Costly & requires quality control Requires more time Can be performed relatively quickly Requires a reliable electricity supply Do not require electricity More complex & requires the competence of a trained microscopist Are relatively easy to perform

18. Treatment of P.vivax cases: 1. Chloroquine : 25 mg/kg body wt divided over 3 days i.e. 10 mg/kg on day 1, 10 mg/kg on day 2, 5 mg/kg on day 3. 2. Primaquine : 0.25 mg/kg body wt daily for 14 days Primaquine is contraindicated in infants, pregnant women and individuals with G6PD deficiency It can lead to hemolysis in G6PD deficiency.

19. 14 day regimen of Primaquine should be given under supervision Patient should be advised to stop primaquine immediately if he/she develops any of the following symptoms and should report to the doctor immediately; ( i ) dark coloured urine (ii) yellow conjunctiva (iii) bluish discolouration of lips (iv) abdominal pain (v) nausea, vomiting (vi) breathlessness, etc.

20. Treatment of uncomplicated P.falciparum cases: 1. In states other than NE states ; Artemisinin based Combination Therapy (ACT-SP) Artesunate : 4 mg/kg body wt daily for 3 days + Sulfadoxine (25 mg/kg body wt) & Pyrimethamine (1.25 mg/kg body weight) on day 1 + Primaquine : 0.75 mg/kg body wt on day 2 .

21. ACT is supplied free of cost for all ages since 2006 Monotherapy of Artemisinin derivatives is BANNED in India since 2009. ACT is not to be given in 1 st trimester of pregnancy “ Different coloured Blister Packs ” have been introduced for treatment of uncomplicated falciparum malaria in different age groups. This has made administration of treatment by field level staff easy.

22. 2. In North-Eastern states : Due to resistance to currently used ACT-SP , effective combination of Artemether-Lumefantrine ( ACT-AL ) has been recommended Co-formulated ACT-AL tablets given according to age group ; Artemether 20mg & Lumefantrine 120mg ( twice daily for 3 days ) Primaquine : 0.75 mg/kg body wt on day 2

23. 4. Treatment of mixed infections ( P.vivax + P.falciparum ) cases : All mixed infections should be treated with full course of age-specific ACT and Primaquine 0.25 mg/kg body wt daily for 14 days . In NE states : ACT-AL for 3 days + Primaquine 0.25 mg per kg body wt daily for 14 days. In other states : ACT-SP for 3 days + Primaquine 0.25 mg per kg body wt daily for 14 days.

24. 5. Treatment of severe malaria cases: Severe malaria is an emergency and treatment should be given as per severity and associated complications which can be best decided by the treating physicians. Should do RDT and take blood smear first Immediately give a parenteral dose of artemisinin derivative (or) quinine in suspected cerebral malaria cases The parenteral treatment in severe malaria cases should be given for minimum of 24 hours once started (irrespective of the patient’s ability to tolerate oral medication earlier than 24 hours).

25. SHORT TERM CHEMOPROPHYLAXIS ( UPTO 6 WEEKS ) CHEMOPROPHYLAXIS FOR LONGER STAY ( MORE THAN 6 WEEKS ) Doxycycline Mefloquine 100 mg once daily & 1.5 mg/kg once daily for children 250 mg weekly for adults Should be started 2 days before travel & continued for 4 weeks after leaving the area Should be administered 2 weeks before & 4 weeks after exposure Contraindicated in pregnant women & children < 8 yrs Contraindicated in individuals with history of convulsions, neuropsychiatric problems & cardiac conditions

26. An optimal response to therapy is when On Day 1 counts less than Day 0 On Day 3 < 25% countscompared to Day 0 No parasites seen in PS after 72 hrs of treatment and upto 28 days No fever after 72 hrs

27. Resistance should be suspected if in spite of full treatment with no history of vomiting, diarrhoea, patient does not respond within 72 hours , clinically and parasitologically .

28. Monitoring of Resistance Since 2003, WHO protocol on “Therapeutic efficacy of antimalarial drugs in uncomplicated P.falciparum malaria” is being followed to assess the efficacy of antimalarial drugs . The response is interpreted into 3 Categories ; Adequate Clinical and Parasitological Response (ACPR): - After treatment patient is considered cured if he/she does not have fever or parasitaemia till Day 28

29. 2. Early Treatment Failure (ETF): Danger signs or severe malaria on day 1,2 or 3 in the presence of parasitaemia Parasitaemia on day 2 higher than day 0, irrespective of axillary temperature Parasitaemia on day 3 with axillary temp ≥ 37.5 °C Parasitaemia on day 3 ≥ 25% of count on day 0

30. 3. Late Treatment Failure (LTF): i ) Late Clinical failure Danger signs or severe malaria on any day between day 4 to 28 , in presence of parasitaemia (without ETF criterion) Parasitaemia on any day between day 4 to 28 + axillary temp ≥ 37.5ºC (without any ETF criterion) ii) Late Parasitological failure Parasitemia on any day between day 7 to 28 with axillary temp < 37.5ºC (without any criterion of ETF & LCF)