Tropical Medicine 2 Flashcards

Question

59. Chicken pox a. has an incubation period of 3-5 days b. rash is preceded by Koplic's spots in the mouth c. fever settles when the rash appears d. should be treated by topical acyclovir e. may follow from close contact with a case of shingles

Answer 1

False a. has an incubation period of 3-5 days False b. rash is preceded by Koplic's spots in the mouth False c. fever settles when the rash appears False d. should be treated by topical acyclovir True e. may follow from close contact with a case of shingles The incubation period is 11-20 days, usually 2 weeks. Koplic's spots precede the maculopapular eruption of measles. The fever generally lasts about a week and settles as the last crop of spots appears. The use of acyclovir in uncomplicated chicken pox is controversial. Systemic acyclovir should be used in complicated chicken pox, particularly in adults. Recognised complications of chicken pox include impetigo, pneumonitis, encephalitis and thrombocytopaenia. Non-immunes can acquire chicken pox from people with either chicken pox or shingles. Shingles occurs when immunity is lowered in a person who has suffered from chicken pox in the past.

Answer 2

False a. the virus has double stranded DNA True b. the incubation period is 2-6 weeks True c. the illness is milder in young people False d. is maximally infectious at the peak of jaundice True e. can be prevented by active immunisation Hepatitis A is a single stranded RNA virus. In children the illness may be very mild. Clinical jaundice might not occur. The infectious period is from 2 weeks before the onset of jaundice until 1 week after. The most infectious time is just before onset of jaundice. Hepatitis A is usually acquired by consumption of faecally contaminated food or water. Other gastrointestinal pathogens may be acquired from the same source. Many patients recall having had diarrhoea a few weeks before their jaundice and upto 15% have other pathogens isolated from the stool.

Answer 3

Typical features of tropical splenomegaly syndrome are: False a. very low or absent malarial antibody titres True b. increased serum IgM True c. lymphocytic infiltration of hepatic sinusoids False d. Plasmodium falciparum parasitaemia True e. favourable response to prolonged anti-malarial drug therapy It is characterised by massive splenomegaly and its geographic distribution mirrors that of malaria. Malarial antibodies are present in high titres but there is no parasitaemia. The basis of treatment is prolonged antimalarial chemoprophylaxis.

Answer 4

``` True a. L.donovani False b. L.tropica True c. L.chagasi False d. L.major True e. L.infantum ``` L.donovani, L.infantum, and L.chagasi may all cause visceral leishmaniasis but there geographical distribution differs. L.donovani is found in India and sub-Saharan Africa, L.infantum in the Mediterranean and L.chagasi in South and Central America. L.tropica usually causes cutaneous leishmaniasis but the cause of a small but well documented outbreak of "viscerotropic" leishmaniasis in veterans of Operation Dessert Storm. L.major causes cutaneous leishmaniasis.

Answer 5

False a. pregnancy approximately doubles the rate of progression to AIDS False b. the rate of vertical transmission of HIV is greater than 50% True c. perinatal administration of zidovudine to the mother reduces vertical transmission True d. breast feeding increases vertical transmission. False e. transmission of HIV to the neonate is confirmed if the neonate is HIV antibody positive The rate of vertical transmission is about 15-35%. In Europe it is nearer 15% and in Africa nearer 30%. Zidovudine appears to reduce vertical transmission by 2/3. Nearly all babies born to HIV antibody positive mothers will get antibody to HIV via transplacental transfer. Only 15-35% of these will also be infected by the virus itself. It follows that detection of HIV antibody in neonates does not necessarily indicate HIV infection. HIV infection can be diagnosed by detection of HIV p24 antigen or detection of HIV antibody at age 18 months. The rate of vertical transmission is increased by breast feeding and vaginal delivery. It is also increased if the mother has advanced disease.

Answer 6

``` False a. painful True b. undermined False c. caused by Fusobacterium False d. secondarily infected False e. responsive to penicillin ``` The causative organism is Mycobacterium ulcerans. Treatment is with topical antiseptics and clofazimine or rifampicin. The mode of spread is unknown.

Answer 7

False a. it is caused by Bacillus pestis False b. the main vector is the rat False c. the pneumonic form is more common than the bubonic form True d. fraction I antigen in the bacterial capsular envelope confers anti-phagocytic activity True e. direct person to person spread may occur (i.e. without a vector) Plague is caused by Yersinia pestis. The main animal reservoir is the rat but the vector is the rat flea, Xenopsylla cheopis. Bubonic plague is the more common form. The other forms are pneumonic, septicaemic, and meningeal. Virulence of Y.pestis depends on V and W antigens whose genes are plasmid mediated. The bacterial cell wall contains a potent lipopolysaccharide endotoxin which may cause Gram negative shock. Exotoxins are also produced. Cases of plague should be isolated because person to person spread may occur.

Answer 8

True a. should be given annually to dogs in endemic areas True b. may usefully be given many months after exposure False c. Post-exposure vaccination is unnecessary if pre-exposure vaccination has been given True d. Specific rabies immunoglobulin for human use may be prepared from horse serum False e. is unnecessary after cat bite Pasive immunisation with immunoglobulin derived from horse serum may result in serum sickness. Immunoglobulin derived from human serum also has this problem but to a lesser extent

Answer 9

True a. cases have copious watery diarrhoea False b. intravenous rehydration therapy has no place True c. the most important public health intervention is the provision of clean water and good sanitation False d. mass chemoprophylaxis with oral tetracycline should be arranged urgently False e. mass vaccination should be undertaken Antibiotics reduce the duration of diarrhoea from a mean of 1.8 days to a mean of 0.8 days. Stool volume, intravenous fluid requirements and length of hospital stay are reduced by antibiotics. Tetracyclines, chloramphenicol, cotrimoxazole, doxycycline, ampicillin, ciprofloxacin and furazaladone have been used successfully. Treatment of household contacts with 200mg of doxycycline (single dose) is recommended but mass chemoprophylaxis is not

Answer 10

``` False a. hairy cell leukaemia True b. leiomyosarcoma in young people with AIDS True c. nasopharyngeal carcinoma False d. teratogenesis True e. oral hairy leukoplakia ``` glandular fever chronic fatigue syndrome oral hairy leukoplakia (in HIV infected patients) nasopharyngeal carcinoma leiomyosarcomas in young people with AIDS Burkitt's lymphoma

Answer 11

False a. Surgical removal of cysts should not be attempted True b. It is caused by dog tapeworm False c. It is usually accompanied by eosinophilia True d. It is treated with albendazole False e. It is best diagnosed by microscopy of fluid obtained from ultrasound guided aspiration of the suspected cyst The adult tapeworm's definitive host is the dog

Answer 12

False a. is found in green leafy vegetables True b. high dose supplementation in pregnancy is teratogenic True c. supplementation reduces mortality from measles True d. supplementation reduces mortality from diarrhoeal disease False e. supplementation reduces mortality from respiratory disease Retinol is not found in vegetables. Beta-carotene is found in dark green leafy vegetables, mangoes, papayas, yellow corn, carrot etc. Beta-carotene is a pro-vitamin, converted to vitamin A by enzymes in the gut mucosa Supplementation is advised in communities where children are malnourished or have borderline nutrition. Many clinicians also advocate supplements of vitamin A (200 000 iu daily per os for 2 days, and repeated after 1 week), at time of diagnosis of measles. Measles causes reduced uptake and increased metabolic requirements. Furthermore, the virus itself may cause eye lesions. Xerophthalmia is rare outside the context of protein energy malnutrition.

Tropical Medicine 2 Flashcards

(36 cards)