1. Toxoplasmosis  

 
 Source:     

Cats essential part of life cycle
May be acquired from contact with cat faeces (especially kittens) or undercooked meat
Asymptomatic infection very common: in Europe 50-70% of population have been exposed

Most episodes of clinical infection in AIDS occur due to reactivation of previous unknown infection

 
Clinical presentation:    Fever, headache, personality change, reduced level of  consciousness, paralysis, fits  

 
Diagnosis:                         CT brain scan show multiple oedematous abscesses in cortex or basal ganglia which give ring of enhancement following injection of iv contrast medium  

 
Other investigations:      LP not possible  

Toxoplasma serology +ve (but if available usually takes weeks therefore do not delay diagnosis)

CD4 count <100/ml  

 

 

 
Treatment:                       

Sulphadiazine100mg/kg/d in divided doses plus
Pyrimethamine 75mg/d with folinic acid 15mg/d for 8 weeks

Then lifelong:

Sulphadiazine500mg qds plus
Pyrimethamine 25mg/d with folinic acid 15mg

 
High incidence of rash
Crystaluria and renal impairment
Maintain high fluid intake
Severe neutropaenia if folinic acid not given

 

or

Clindamycin 600mg qds plus
Pyrimethamine 75mg/d with folinic acid 15mg/d for 8 weeks

Then lifelong:

Clindamycin 600mg bd. plus
Pyrimethamine 25mg o.d. with folinic acid 15mg/d  

 
Diarrhoea
Pseudomembraneous colitis  

 
Consider use of steroids if reduced level of consciousness  

 

Complications:             

Consider repeat scan at 4-6 weeks

If no radiological or clinical improvement suspect alternative diagnosis (e.g. lymphoma)

Fits may occur at any time; control with anti-epileptics; advise against driving or operating machinery  

 

 
Infectious risk to others: None  

 

Prevention:                   

New infections prevented by cooking meat thoroughly and washing hands after handling cats (but see above)

Occurrence of encephalitis if CD4<100/ml prevented by                                                           
                                                

Septrin 960mg o.d.

or Dapsone 100mg/d with pyrimethamine 25mg twice weekly and folinic acid 25mg twice weekly  

 
2. Cryptosporidiosis  

 
Source:                         Cattle esp. calves
Drinking water  

 
Clinical presentation:    Severe diarrhoea: no blood or fever; little abdominal pain              
If CD4>200 stops without treatment after 7-10days                       
If CD4<200 diarrhoea persists causing severe weight loss  

 
Diagnosis:                           Stool microscopy (ZN stain) +ve in 90% on repeat sampling; if not,   Consider rectal biopsy  

 

Treatment:                         

 

Difficult without HAART: paromomycin 500mg qds may have temporary effect

Mainly symptomatic: anti-diarrhoeals, fluids and electrolytes  

 
Complications:                  Malnutrition and dehydration  

 
Infectious risk to others: High if immunocompromised  

 
Prevention:                    Essential in view of lack of treatment
All HIV+ve people should boil their drinking water  

 
3. Microsporidiosis  

 
Source:                            Probably from drinking water  

 
Clinical presentation:  As with cryptosporidiosis  

 
Diagnosis:                                          Giemsa stain on stool  

 
Treatment:                      None

 
Complications:              As with cryptosporidiosis  

 
Infectious risk to others: As with cryptosporidiosis  

 
Prevention:                     As with cryptosporidiosis