Lecturer of Occupational Health & Industrial Medicine Malaria Dr. Abd El hamied Mohamed Abd El hamied Lecturer of Occupational Health & Industrial Medicine

MALARIA Acute protozoal disease that becomes chronic if not properly treated.

Public health significance Most prevalent parasite all over the world (tropical & subtropical Africa, Asia, Central & South America). Endemic in 92 countries, 40% of the world's population is at risk (2 billions). Each year 300 million to 500 million clinical cases of malaria (> 90% of them in Africa). 2 million deaths / year (50% in children < 5 years). Malaria is re-emerging disease due to drug resistance & vector resistance to insecticides.

Causative agents 4 species of Plasmodium: P. vivax, ovale, malariae & falciparum. Infection with P. falciparum causes the most severe form of malaria.

Reservoir Human with infective gametocytes in their peripheral blood.

Vector Female Anopheles: A. pharounsis. A. sergenti. A. multicolor. Mosquitoes is the definitive host, the infective stage to man is sporozoite.

Period of infectivity So long gametocytes present in peripheral blood.

Modes of transmission Bite of infective female anopheles mosquito (sporozoites are present in salivary glands). Infected blood transfusion (malaria remain viable in stored or frozen blood for 19 days). In utero infection.

Intrinsic IP P. falciparum: 6 - 12 days. P. vivax: 10 - 17days. P ovale: 14 days. P. malariae: 28-30 days

Susceptibility

Age: Sex: Immunity: Environment Any age (tolerance to disease in highly endemic areas). Sex: Male more exposed usually due to outdoor life. Immunity: Infection → species specific immunity. Environment Hot, humid seasons & rainfall: suitable environment for breeding of mosquitoes. Genetic: Black African show resistance to p. vivax. Socio-cultural: Habits of population such as sleeping outdoors. Travel: People traveling to malarious areas are at risk.

C/P Malaria can mimic anything & everything ! Vary with: Malaria species, Patient’s general condition In endemic area or not. Can appears early ( 6 days) after initial exposure or late ( several months) after leaving endemic area & stopping chemoprophylaxis.

Mild cases: Influenza like symptoms as: persistent headaches, back pain, myalgia, nausea & vomiting.  

Severe cases: Disseminated intravascular coagulation. Pulmonary edema. Death. Intermittent febrile paroxysms: Cycle of chills, fever & sweating. 3 stages, repeated either daily or every other day or every 3rd day depending on species of malaria.

Sequelae & Complications Anaemia. Abortion or congenital infection. Pigment stones due to haemolysis of RBCs. Black water fever (haemoglobinuria) precipitated by Quinine in small dose. Burkitt' lymphoma (Parasites causing cancer?) Nephrosis in long standing p. malariae Impaired liver function & Impaired capillary circulation (cerebral & intestinal) in p. falciparum.

Diagnosis Case definition: Malaria is a complex disease With a broad clinical spectrum of disease From asymptomatic infections to disseminated intravascular coagulation, pulmonary edema & death.

Asymptomatic malaria Suspected case Confirmed case Person with no symptoms and /or signs of malaria with laboratory confirmation of parasitemia. Patient with unexplained fever + history of travel or residence in an endemic region. Detection of malaria parasites on smear.

Malaria survey

Definition: field study in endemic areas to find out the magnitude of malaria problems and ecological factors related to endemicity (host-agent-environment)

Steps: Planning Preparation Implementation &interpretation: Vector study: types of mosquito, aquatic stages, density, species, life span, choices to host resting habits, breedig habits, resistance to insectisides.

Malaroimetric indices A-Human: 1-splenic index (non specific): the percentage of children between 2-9 years showing enlargement of spleen, excluding other causes of spleenomegaly (Bilharisiasis and Leshmania). 2-gametocyte index (spesific): the percentage of the host having gametocytes in their blood.

3-infant parasitic index (specific): the percentage of the infants below the age of one year showing malaria parasites in their blood. It is the most sensitive index for recent infection. What is the most specific human index?

B-Vector Indices: 1.Oocyte index: percentage of oocyte in the stomach wall of female anopheles. 2.Sporosoite index: percentage of female anopheles having sporosoite index in their salivary glands.

General Prevention

1.Sanitary environment Filling of water collections to eliminate breading places of mosquitoes. 2.Eradication Of larval stage: Biologically: by natural enemies as frogs, ducks & Gambusia fish or Chemically: by spraying crude oil & larvicides on water surface. 3.Destruction of adult mosquitoes: By spraying of screened living & sleeping mosquitoes with a liquid aerosol.

4.Personal protection against bites: (the first line) Avoid outdoor exposure between dusk & dawn. Wearing long loose clothing after dusk with light color. Avoid perfumes & colognes. Use effective insect repellents. Using mosquito coils , knock- down sprays. Plug in vaporizing devices indoor. Using mosquito nets.

5.HE: Of public for mode of transmission, protection & importance of treatment. 6.Blood donors: With positive history should be avoided.

Control

I. Case Early case finding. 2. Notification: to LHO. 3. Isolation: not required. 4. Treatment: started immediately.

Recommended Frequency of Notifiable diseases Reporting

Group A (Immediate reporting) Meningitis (GOO, A39, A87) AFP/poliomyelitis HIV/AIDS (B20-B24) Rabies/Animal Bite Diphtheria Malaria Plague Tetanus Acute food poisoning Viral hemorrhagic fever (A90,A91) Rift valley fever. Botulism. Cholera

(Weekly reporting) (Monthly reporting) Group B (Weekly reporting) Group C (Monthly reporting) Typhoid Brucellosis TB Measles Pertussis Dysentery. Viral hepatitis Mumps Rubella Schistosomiasis Leprosy Fasciola Filariasis

ICD-10 classifications It is international classification of diseases number 10 provides code numbers & case definitions to standardize diagnosis on the national & international level.

Diseases are grouped according to: timing of reporting & need for public health action. Group A diseases: require prompt public health action by the District Surveillance Unit (DSU) & should be immediately reported by phone or fax. Most of group B: require more in-depth investigation & monitoring by the DSU. Group C diseases: are reported on a monthly basis.

II. Contacts 1. Enlistment: age & sex. 2. Investigation of contacts & source of infection.

III. Epidemic measures 1. Single case of malaria of endogenous origin constitutes an outbreak. 2. Aggressive outbreak control.

IV. International measures for travelers (Checklist for Travelers to Malarious Areas) Risk for Malaria. Personal Protective Measures. 3) Chemoprophylaxis: 4) In case of illness 5) Special categories: Pregnant women Young children

1) Risk for Malaria Higher in sub-Saharan Africa than other part in the world. No vaccine is currently available (vaccine under trial). Appropriate chemoprophylaxis & anti-mosquito measures will help prevention.

2) Personal Protective Measures

3) Chemoprophylaxis a. General recommendation for primary prophylaxis. b. Terminal prophylaxis.

a. General recommendation for primary prophylaxis Drug Usage Before Travel During travel After Chloroquine Weekly 1 - 2 weeks Continue 4 weeks Mefloquine Doxycycline Daily days Proguanil 7 days

Areas without Chloroquine-Resistant P. falciparum Areas with Chloroquine-Resistant P. falciparum Areas with Mefloquine-Resistant P. falciparum Chloroquine: once- a-week. Hydroxychloroquine sulfate, compound better tolerated. Proguanil, doxycycline or mefloquine: for travelers unable to take chloroquine orhydroxychloroquine Proguanil. Doxycycline. Mefloquine.

b. Terminal prophylaxis To prevent relapse that may occur 4 years or more after chemoprophylaxis. Primaquine to prevent relapse with p.vivax & p.ovale. For 14 days after travelers has left malaria endemic areas.

4) In case of illness Travelers should get information on mild symptoms. Warned that delay in treatment is fatal.

5) Special categories Pregnant women. Young children.

Malaria in pregnancy ↑ morbidity & mortality for mother & fetus. Pregnant women should be advised to: Avoid travel to malarious areas if possible. 2. Stick to anti-mosquito measures & chemoprophylaxis. 3. Seek care if symptoms of malaria developed ( treated as medical emergency).

Chloroquine-Resistant Travel to Areas where P. falciparum is Not Chloroquine- Resistant Chloroquine-Resistant Pregnant females: Chloroquine (not harmful to fetus) Mefloquine (No adverse effects on fetus or pregnancy in 2nd & 3rd trimesters). Infants, Children & Adolescents: Doxycycline: for children > 8 years.

Not Recommended Proguanil: limited data on safety. Doxycycline: discoloration & dysplasia of teeth & inhibition of bone growth. Primaquine: hemolytic anemia in utero in G6PD-deficient fetus.

Malaria Eradication

Disease elimination & eradication

Criteria for diseases suitable for elimination or eradication: Causative agent is antigenically potent and stable.   Man is the only reservoir, no animal or soil reservoir.  Disease occurs in clinically apparent persons detected by adequate surveillance system. No subclinical cases or carriers. Disease has a long incubation period. 

Modes of transmission are limited and well defined.   Post infection immunity or immunization is strong & life lasting. Availability of effective control measures. Availability of resources (human and non human) to implement the program for elimination or eradication.

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