Amoebic Infections
Amoebic infections and treatments
Eight species of amoebae infect man. The gut lumen which is one of the tissues of the central nervous system is a host to seven of these parasites. They vary in size with species .
Entamoeba histolytica is the only one species regarded as an important pathogen to man which is a compolitan parasite and is more common in tropical and subtropical regions in temperate climates.
Hartmanella and Naegleria previously thought to be free living organisms in the damp soil have records of causing primary meningo-encephaltis.
EPIDEMOLOGY
Ingestion of cysts of entamoeba histolytica is the mode of transmission,cysts are resisistant to antiseptics such as mercuric chloride,formalin and chlorine, but are killed by dessicatiion and heat at about 500 degrees celcius.
Contamination of food by cysts is associated with contaminated water suppilies,low standards of hygiene in food handling, transport by flies and coakroaches in which cyst survive 48 hours. The use of human faeces as manure,low standards of personal hygiene and leakage of sewage into the water supply.
INFECTION
Infection isacquired by the ingestion of cysts in cotaminated food or water. Amoebae penetrate into the submucosa through the mucosal crypts of the intestine and multiply forming abscesses.
Amoebic abscess occurs most commonly in the right lobe of the liver because of the initiation of gut lesions in the caecal region.
Through some biochemical transport systems they get to the gut as flask ulcer forming lesions particularly in the rectum and sigmoid colon andperforate into the peritoneal cavity.
Lymphatic and blood vessels may spread amoebae and bacteria from the intestinal lesions to other parts of the body which results in Hepatitis.
Other sites sometimes affected are the skin particularly in the perianal and perineal regions, and the penis as a result of unnatural sexual practices.
Infection by Hartmanella and Naegleria is associated with swimming in freshwater lakes or pools or playing in muddy water.
SYMPTOMS
Symptoms tend to develpo gradually, intermittent diarrhoea and constipation, abdominal discomfort,nausea,vomiting and loss of appetie.
Intermittent fever, night sweats, and pain in the upper right abdominal quadrant are symptoms for liver infection.
The onset of primary amoebic menino-encephalitis is typically sudden,with headache and fever,progressing to vomiting,neck and back rigidity and mental confusion,coma and death in some 4 to 7 days.
TREATMENT
Methronidazole, emetine bismuth iodide and diloxamide furoate are recommended, for intestinal infections.
Emetine hydrochloride with chloroquine or methronidazole are drugs of choice when the liver is involved. Emetine may be contraindicated by its cardiotoxicity.
Amphotericin B may be effective in tratment of primary meningo-encephalitis, early institution of treatment is importatant
