Community and Public Health PDF

NATIONAL UNIVERSITY-MANILA COMMUNITY AND PUBLIC HEALTH AL GENESIS F. SALES, RMT NATIONAL UNIVERSITY-MANILA LESSON 3 MEDICAL AND PUBLIC HEALTH PARASITOLOGY  INTRODUCTION T...

NATIONAL UNIVERSITY-MANILA COMMUNITY AND PUBLIC HEALTH AL GENESIS F. SALES, RMT NATIONAL UNIVERSITY-MANILA LESSON 3 MEDICAL AND PUBLIC HEALTH PARASITOLOGY  INTRODUCTION TO PARASITOLOGY PARASITOLOGY The science that deals with the study of living organism (parasite) that depends on another organism (host) for the purpose of procuring food and securing protection. Parasites – organism that obtain its food and shelter from another organism and derive all the benefits from the association Host – organism that provides physical protection and nourishment to the parasite SYMBIOSIS a close association between two organisms that is permanent wherein one cannot exist independently. 1. Mutualism – both the parasite and the host benefits 2. Commensalism – only the parasite (non-pathogenic) benefits and the host is unaffected 3. Parasitism – the parasite benefits while damaging the host  PARASITES NEMATODES TREMATODES (Roundworms) (Flatworms / Flukes) CESTODES (Tapeworms) PROTOZOA TYPES OF PARASITES 1. OBLIGATE – host is a requirement, takes up permanent residence and is completely dependent upon its host for existence throughout its life 2. FACULTATIVE – capable of leading both free and parasitic existence under favorable or appropriate circumstance 3. INCIDENTAL – one that establishes itself in a host in which it does not ordinarily lives 4. TEMPORARY – free living during part of existence and seeks only its host intermittently to obtain nourishment 5. PERMANENT – remains on or in the body of the host from early life to maturity 6. SPURIOUS / COPROZOIC – one which parasitizes other hosts and recovered in a living dead state from human excreta no further development and do not cause injury TYPES OF HOST 1. FINAL / DEFINITIVE HOST – harbors the adult / sexual stage of the parasite 2. INTERMEDIATE HOST – harbors parts or all the larval stages (asexual) of the parasites a. First intermediate host – early larval stage / non-infective b. Second intermediate host – late larval stage /infective 3. RESERVOIR HOST – Other animals that harbors the same species as that or man but doesn’t get infected. Serves as an additional source of infection 4. PARATENIC HOST – Harbors the parasite in an arrested state of development or dormancy (the parasite enters in a larval from and doesn’t continue to develop)  PARASITISM Parasitic Infection – infective agent becomes established in the host (mild symptoms and little damage) Parasitic Disease – the host develops pathologic changes (exhibit symptoms of varying degree) Factors Affecting the Transmission of Parasite 1. The source of infection 2. An effective mode of transmission and portal of entry 3. The presence of a susceptible host 4. Successful entry of the infective stage of the parasite DISTRIBUTION OF DISEASE 1. ENDEMIC– a disease is human population maintains steady, moderate level 2. EPIDEMIC – sharp rise in the incidence or an outbreak of considerable intensity occurs 3. HYPERENDEMIC – prevalence of a disease in a community is high 4. SPORADIC – the disease appears only occasionally in one or few members of a community 5. PANDEMIC – disease covers extensive area of the world, global scale INCUBATION PERIOD 1. Clinical Incubation Period From the time of exposure up to the appearance of the earliest signs and symptoms The adult parasite is the one responsible for the sign and symptoms 2. Biological Incubation Period From the earliest signs and symptoms up to the time where the laboratory results become positive The birth of female parasite (the egg is already in the feces) will give a positive result and if negative, the male and female is still copulating In the laboratory, 3 stool samples or examination is needed for the confirmation of the result  SOIL-TRANSMITTED HELMINTHS It is the third most prevalent infection worldwide, second only to the diarrheal disease and tuberculosis The prevalence of STH among the 2 to 5 years old is lesser but they suffer the greatest impact of the disease when they get infected The three major causes of intestinal parasitic infections in the Philippines are: - o Ascaris lumbricoides (Giant intestinal roundworm) o Trichuris trichiura (Whipworm) o Hookworm ▪ Ancylostoma duodenale (Old world hookworm) ▪ Necator americanus (New world hookworm)  They are classified as soil transmitted helminthes because their major development takes place in the soil. Geofactors like temperature, humidity, wind etc. are the primary factors which determine their distribution With unsanitary disposal of human stool, eggs from these parasites develop in the soil and can mechanically infect humans when fingers, food or water are contaminated with parasite eggs from the soil where they became infective or when the infective larva of hookworms in the soil penetrate skin of barefooted individuals SIGNS AND SYMPTOMS Anemia Malnutrition Stunted growth in height and body size Decreased physical activities Impaired mental development TREATMENT Piperazine citrate, pyrantel pamoate, mebendazole, albendazole, levimazole depends on what parasite is present PREVENTION AND CONTROL Health education o Good personal hygiene – thorough washing of hands before eating and after using toilet o Keeping fingernails short and clean o Use of footwear o Use of sanitary facilities like toilets o Sanitary disposal of feces Early diagnosis and treatment o Laboratory examination of stool (fecalysis) o Ensure proper dosage of medication and completion of treatment  ENTEROBIASIS / OXYURIASIS It is a group infection and is more common in infected families and asylums Studies conducted showed that eggs were collected under fingernails and fingertips. The eggs adhere well on surface of the skin and by their mucoid secretions cause irritation and characteristic nocturnal perianal or perineal itching → “pruritus ani” CAUSATIVE AGENT Enterobius vermicularis (Pinworm) TRANSMISSION Autoinfection – Ingestion of eggs due to scratching of perianal area with fingers leading to deposition of eggs under the nails Retroinfection – the eggs laid on the perianal skin immediately hatch into the infective stage larva and migrate through the anus to develop into worms in the colon DIAGNOSIS Cellulose Tape Anal Swab Technique TREATMENT The infection is self-limited and in the absence of reinfection, ceases without treatment Drugs that can be used: Albendazole, Mebendazole, Pyrantel pamoate PREVENTION AND CONTROL Treatment of infected children and other members of the family Improved personal hygiene and cleanliness such as: o Cutting the nails short o Strict hand washing before and after eating and after using the toilet o Washing the bed linens and night dress  SCHISTOSOMIASIS Also known as the Bilhariasis or Snail Fever has long been one of the important tropical diseases in our country. It is caused by a blood fluke that is transmitted by a tiny snail Oncomelania hupensi quadrasi. Since it affects mostly farmers and their families in the rural area it results in manpower losses and lessened agricultural productivity. There is a high prevalence of Schistosomiasis in Region 5 (Bicol), Region 8 (Samar and Leyte) and Region 11 (Davao) CAUSATIVE AGENT Schistosoma japonicum Schistosoma mansoni Schistosoma haematobium MODE OF TRANSMISSION Infection occurs when the skin comes in contact with contaminated fresh water in which certain types of snails that carry scistosomes are living. It is a free- swimming larval form (cercaria) of the parasite that penetrates the skin. Fresh water becomes contaminated when infected people urinate or defecate in water. SIGNS AND SYMPTOMS Diarrhea Bloody stool Enlargement of the abdomen Splenomegaly Weakness Anemia Hepatitis TREATMENT Praziquantel is the drug of choice against all species. Alternative drugs are Oxamniquine for S. mansoni and Metrifonate for S. haematobium METHODS OF CONTROL 1. Preventive measures Educate the public in endemic areas regarding the mode of transmission and methods of protection Proper disposal of feces and urine Improve irrigation and agriculture practices: reduce snail habitats by removing vegetation Treat snail-breeding sites with molluscicides Prevent exposure to contaminated water Provide water for drinking, bathing and washing clothes from sources free of cercaria or treatment to kill them Treat patients in endemic areas to prevent disease progression Travelers visiting in endemic areas should be advised of the risk and informed about preventive measures 2. Control of Patient, contacts and the environment Report to local health authority No need for isolation and quarantine to infected people and those who are at risk Concurrent disinfection: sanitary disposal of feces and urine 3. Investigation of contacts and source of infection Epidemic measure: examine for Schistosomiasis and treat all who are infected but especially those with moderate to heavy infection, pay particular to children Motivate people in these areas to have annual stool exam  PARAGONIMIASIS It is a chronic parasitic infection, which greatly reduces human productivity and quality of life. It is frequently encountered in communities where eating of fresh or inadequately cooked crabs is a practice. The manifestations closely resemble PTB that most often it is misdiagnosed for this disease in endemic areas ENDEMIC AREAS The provinces of Mindoro, Camarines Sur, Camarines Norte, Sorsogon, Samar, Leyte, Negros Islands, Albay, Cebu, Basilan Commonly patients with Paragonimiasis are misdiagnosed to have PTB and are treated as PTB patients. In fact, a study by Dr. Vicente Belizario Jr. et al, revealed that 56% of his subjects were nonresponsive to a multi-drug therapy for PTB but were positive for Paragonimiasis CAUSATIVE AGENT Paragonimus westermani (Lung Fluke) INTERMEDIATE HOST First IH – Fresh water snail (Antemelania asperata) Second IH – Small, fresh water crab (Sundathelpusa philippina) MODE OF TRANSMISSION Ingestion of raw or insufficiently cooked infected crabs Contamination of food or utensil with metacercaria during food preparation Drinking of water contaminated with infective larvae SIGNS AND SYMPTOMS PTB-like symptoms not responding to anti-TB medications Cough Hemoptysis Chest and back pain DIAGNOSIS Sputum examination Immunology Cerebral Paragonimiasis – Eosinophilia in CSF TREATMENT Praziquantel is the drug of choice given 25 mg./kg body weight three times daily for three days. Bithionol is the alternative drug.  FILARIASIS Public Health concern in many endemic areas (45 out of 78 provinces are endemic) CAUSATIVE AGENT Wuchereria bancrofti Brugia malayi and/or Brugia timori MODE OF TRANSMISSION: The disease is transmitted to a person through bites from an infected female mosquito VECTOR Wuchereria – Aedes poecilus, Anopheles minismus flavirostris Brugia – Mansonia bonnaea, Mansonia uniformis STAGES OF FILARIASIS 1. Asymptomatic stage Characterized by the presence of microfilariae in the peripheral blood No clinical signs and symptoms of the disease 2. Acute stage Lymphadenitis – inflammation of the lymph nodes Lymphangitis – inflammation of lymph vessels In some cases, the male genitalia is affected 3. Chronic stage Developed 10-15 years from the onset of first attack Hydrocoele – swelling of the scrotum Lymphedema – swelling of the upper and lower extremities Elephantiasis – enlargement or thickening of the skin of the lower and/or upper extremeties, scrotum, breast LABORATORY DIAGNOSIS Blood Examination – thick blood smear about the size of 25 centavo coin, blood is taken from the patient 10pm to 2am for Wuchereria and anytime for Brugia but more preferred at night. (due to parasite’s periodicity) TREATMENT The drug of choice is Diethylcarbamazine (DEC) SUPPORTIVE CARE Patients are advised to observed personal hygiene by washing the affected areas with soap and water at least twice a day or prescribed antibiotics or anti-fungal for super infection PREVENTION AND CONTROL 1. Environmental sanitation such as proper drainage and cleanliness of the surroundings o Use of insecticides 2. Measures aimed to protect the people in endemic areas o Use of mosquito nets o Application of insect repellants o Screening of houses  MALARIA Continues to be a major public health concern having an annual parasite incidence of 5.1 per 1000 population CAUSATIVE AGENT Plasmodium falciparum Plasmodium malariae Plasmodium vivax Plasmodium ovale MODE OF TRANSMISSION Through the bite of an infected female mosquito or directly from one person to another by passage of blood containing erythrocytic parasites SIGNS ANG SYMPTOMS Recurrent chills and Fever (Paroxysm) Profuse sweating Anemia Hepatosplenomegaly LABORATORY EXAMINATION Thick and thin blood smear – look for the presence of malarial parasite Para Sight F test (Histidine-rich Protein II) – dipstick test for simple and rapid diagnosis of Plasmodium falciparum Lactate Dehydrogenase – Plasmodium spp. Serological test – IHA (Indirect Hemeagglutination) ELISA (Enzyme-linked Immunosorbent Assay) TREATMENT Drug of choice is Chloroquine. Pyrimethamine/sulfadoxine combination maybe used in areas with high levels of resistance to chloroquine CHEMOPROPHYLAXIS Only chloroquine should be given. It must be taken at weekly intervals starting from 1-2 weeks before entering endemic areas PREVENTION AND CONTROL Sustainable preventive and vector control o Insecticide – treatment of mosquito nets o House spraying o Protective clothing o Educate the people in endemic areas o Chemoprophylaxis  PARALYTIC SHELLFISH POISONING "PSP Red Tide Poisoning" A syndrome of characteristic symptoms predominantly neurologic which occur within minute or several hours after ingestion of poisonous shellfish Ingestion of raw or inadequately cooked seafood usually bi-valve shellfish or mollusk during red tide season CAUSATIVE AGENT Single-celled organism called Dinoflagellates; it is commonly referred as Plankton The organism that causes red tide in the seas around Manila Bay, Samar, Bataan and Zambales is the Pyromidium bahamense var. compressum SIGNS AND SYMPTOMS Numbness of face especially around the mouth Vomiting and dizziness Headache Tingling sensation and eventually paralysis of hands and feet Floating sensation and weakness Rapid pulse Difficulty of speech (ataxia) and difficulty in swallowing (dysphagia) Total muscle paralysis with respiratory arrest and death occur in severe cases MANAGEMENT AND CONTROL No definite medication is required Induce vomiting Drinking pure coconut milk and sodium bicarbonate solution weakens the toxic effect of red tide. It is advised to take these solutions in early stage of poisoning only Shellfish affected by red tide must not be cooked with vinegar as the toxin of Pyromidium increases when mixed with acid Toxin of red tide is not totally destroyed upon cooking hence consumers must be educated to avoid bi-valve mollusk such as tahong, talaba, halaan, kabiya when red tide warning has been issued by proper authority NATIONAL UNIVERSITY-MANILA END OF DISCUSSION THANK YOU!