18 Infectious disease

Follow manufacturers’ instructions. Do not store vaccines in the door of a vaccine fridge and make sure there is a maximum and minimum thermometer in the fridge. Record readings regularly and discard vaccines if not stored at the correct temperature.

Only suitably trained GPs/nurses should give immunizations. Check immunization is needed and the patient is fit. Check consent has been obtained and that immunizations are the correct ones and in date. Ensure resuscitation facilities are available. Record vaccine expiry date/batch number. Reconstitute vaccine (if necessary) and give according to manufacturer’s instructions. Record date and site in the medical notes.

Available as a Directed Enhanced Service—existing practices do not have preferred provider status. Additional payments are available through the Quality and Outcomes Framework for ensuring at-risk patients receive vaccination.

Can be provided as an Additional Service. Opting out incurs a 2% ↓ in global sum. A list of eligible vaccinations and terms of eligibility is available on the BMA website (  www.bma.org.uk). Travel vaccinations that do not fall into these criteria can be administered as a private service.

For specific contraindications to individual vaccinations consult the Green Book. General rules:

(BCG; shingles; measles; mumps; oral typhoid; rubella; yellow fever). Do not give live vaccines:

Patients with HIV who are not severely immunosuppressed may have live vaccine except BCG and yellow fever.

Only payable if a patient is >60% impaired by a vaccination given within the NHS. Recipients receive a lump sum. Further information: 01772 899944  www.gov.uk.

Specific symptoms and signs of infection depend on the infecting organism and organs affected. For example, a chest infection will cause respiratory symptoms; a urine infection, urinary tract symptoms. Symptoms suggesting an infectious cause include:

Palpable enlargement of the LNs.

Lymphoma, CLL, ALL, metastases.

Refer immediately for urgent investigation^N if:

Most enlarged lymph nodes are reactive lymph nodes—suggested by a short history, soft tender mobile lump, and concurrent infection. If there are no sinister features, give these 2wk to settle. If not settling, check FBC, ESR ± EBV screen. Refer lymphadenopathy >1cm diameter persisting for >6wk for urgent further investigation.

p. 874

Shaking episodes (sometimes violent) associated with sudden rise in fever.

Consider TB, lymphoma, leukaemia, solid tumour (e.g. renal carcinoma), menopause, anxiety states, drug causes, e.g. opioids, SSRIs.

Defined as a fever (either intermittent or continuous) which has lasted for >3wk and for which no cause has been found. Recheck history. Re-examine carefully. Check FBC; EBV screen (depending on age of the patient); ESR; CRP; LFTs; amylase, urine (M,C&S); viral titres (including HIV); blood cultures; and CXR. If cause does not become obvious refer urgently for further investigation.

Notification of certain diseases is required under the Public Health (Control of Disease) Act 1984 and Health Protection (Notification) Regulations 2010. Notification is made to the ‘proper officer of the local authority’ on forms available from the HPA website (  www.hpa.org.uk). Diseases included:

In addition, notify other infections or contamination which could present significant risk to human health.

Ask about:

Full examination. Particularly check for fever, jaundice, abdominal tenderness, chest signs, rashes, lymphadenopathy.

Depend on symptoms and examination findings. Consider: FBC, malaria testing (consult local protocols), LFTs, viral serology, blood culture, stool culture (ensure it is fresh), MSU.

2,000 cases/y are notified in the UK. Easy to miss.

Caused by Plasmodium falciparum. Accounts for ~½ UK cases—it may not present for up to 3mo after return from a malarial area. Can be fatal in <24h—especially if it occurs in pregnant women or small children (<3y). Complications: cerebral malaria (80% deaths); hypoglycaemia; renal failure; pulmonary oedema; splenic rupture; disseminated intravascular coagulation; death.

Caused by P. vivax, P. ovale, and P. malariae. May cause illness up to 18mo after return. All have very low mortality. Relapse may occur at intervals after initial infection as parasites lie dormant in the liver (P. vivax and P. ovale) or blood (P. malariae).

Caused by Salmonella typhi and Salmonella paratyphi; ∼200 cases/y are notified in the UK.

Viral infection endemic in tropical and subtropical regions. ∼150 cases/y are notified in the UK.

50% travellers experience some diarrhoea. Most cases last 4–5d; 1–2% last >1mo. In all cases send a fresh stool sample for M,C&S at first presentation, noting on the form areas visited. Consider all the usual causes for diarrhoea ( p. 377) and gastroenteritis ( p. 410). In addition consider:

Caused by Gram −ve bacterium Vibrio cholerae.

∼3,800 cases/y are notified in the UK. Flagellate protozoan. Infection is suggested by an incubation period ≥2wk; watery stool with flatus ++ (explosive diarrhoea); no fever. Stool microscopy may be −ve. If suspected treat with metronidazole. Rapid response is diagnostic.

∼100 cases/y are notified in the UK. May begin years after infection. Diarrhoea begins slowly becoming profuse and bloody ± fever ± malaise. Diagnosis is confirmed by microscopy of fresh stool. Take specialist advice on management.

pp. 738–749

p. 746

p. 326

p. 422

p. 1078

p. 742

Infections in patients whose host defence mechanisms are compromised range from minor to fatal. They are often caused by organisms that normally reside on body surfaces.

Infections from endogenous microflora that are non-pathogenic or from ordinarily harmless organisms. Occur if host defence mechanisms have been altered by:

The precise character of the host’s altered defenses determines which organisms are likely to be involved. These organisms are often resistant to multiple antibiotics.

Expert care is always required—refer promptly to the consultant responsible for the patient.

Used for prevention of:

See Table 18.3.

Can prevent or ameliorate herpes zoster (VZ-Ig), hepatitis A and B, measles, and cytomegalovirus infection in selected immunosuppressed patients. If a patient is in contact with any of these diseases seek advice from the consultant looking after the patient or a consultant in communicable disease control.

Effective for patients with hypogammaglobulinaemia. Given on a regular basis by IV infusion.

All asplenic patients (or functionally asplenic patients, e.g. patients with sickle cell disease) are at ↑ risk of bacterial infection. Warn patients about severe malaria and other tropical infections when travelling abroad. Admit to hospital if infection develops despite prophylactic measures.

p. 746

Start vaccinations ≥2wk before splenectomy or starting immuno-suppressive treatment.

For infections listed in Table 18.4, management is supportive with paracetamol, fluids ± antibiotics for 2° infection. Teething gels may soothe mouth lesions in hand, foot, and mouth disease. Admit if any serious complications develop.

Measles, mumps, and rubella (MMR) vaccination consists of live attenuated measles, mumps, and rubella viruses. Vaccine viruses are not transmitted.

There is no evidence that vaccination in pregnancy is harmful, but do not give to women known to be pregnant and advise women who are vaccinated to avoid pregnancy for 1mo afterwards.

Reactivation of latent chickenpox virus. Shingles cannot be acquired by exposure to chickenpox but contacts of patients with shingles can develop chickenpox. Infectious until all lesions have scabbed.

Post-herpetic neuralgia; dissemination to other areas (immunosuppressed patients—admit for IV antivirals); eye involvement—refer for same day assessment to ophthalmology; Ramsay Hunt syndrome ( p. 538).

Several groups are pathogenic to man—A, B, C, G, D, and viridans streptococci. Presentation is varied:

Diagnosis is usually clinical. Evidence of infection can be gained by measuring changing antibody response (ASO titres). ASO titres are ↑ in ~80% infections. Swabs are +ve if infection is on the skin or in the throat or vagina.

Most streptococci are sensitive to penicillin (e.g. penicillin V 250–500mg qds for 7–10d) although resistance is increasingly common.

There are >85 types of S. pneumoniae. Pneumococci are carried in the noses and throats of half the population. In most people they are harmless. Spread is by droplet infection.

Amoxicillin 250–500mg tds for 7d (clarithromycin in allergic individuals). Resistance to penicillin in the community is still low.

Routine vaccination is offered as part of the childhood immunization programme ( p. 645) using 13-valent pneumococcal conjugate vaccine (PCV) given at 2mo, 4mo, and 12–13mo of age.

A single dose of pneumococcal polysaccharide vaccine (PPV) is indicated for high-risk patients (see Box 18.1) who have not previously been vaccinated. Special rules apply to patients who are immunosuppressed or have deficient spleens (see Table 18.4, p. 651). Booster doses are not needed except for patients with asplenia or nephrotic syndrome—when give a booster after 5–10y.

Group A haemolytic streptococcal infection. Incubation: 2–4d. Presents with fever, malaise, headache, tonsillitis, rash (fine punctate erythema sparing face, ‘scarlet’ facial flushing), and strawberry tongue (initially white turning red by third/fourth day). Treat with penicillin V 250–500mg qds for 10d (or clarithromycin if allergic). Complications include rheumatic fever ( p. 276) and acute glomerulonephritis.

Usually Staph. aureus—occasionally Staph. epidermidis. Carried in the nose of ∼30% of healthy adults. Antibiotic-resistant strains are common.

Antibiotics (usually flucloxacillin 250–500mg qds or clarithromycin 250–500mg bd for 7–10d), abscess drainage where appropriate and general supportive measures. Where possible obtain specimens for culture before instituting or altering antibiotic regimens.

p. 903

MRSA acts in the same way as any other Staph. aureus—it is carried harmlessly in most but occasionally causes a range of infections. It is only different because of its multiple resistance to antibiotics. Often contracted in hospital.

Caused by staphylococcal exotoxin.

Vaccination against Hib is routinely offered to all children ( p. 645) and immunocompromised patients ( p. 651). Prior to routine vaccination, Hib infection accounted for 60% of meningitis in children aged <5y. It was also a common cause of epiglottitis, septicaemia, and septic arthritis/osteomyelitis. Infection is now rare.

Non-encapsulated Haemophilus influenzae (ncHi) usually causes non-invasive respiratory tract infections, e.g. OM, sinusitis. It can cause invasive disease in neonates (<1mo of age) and those with co-morbidities e.g. malignancy, immunosuppression, DM, chronic renal/liver/lung disease. Other H. influenzae serotypes (Hia, Hic, Hid, Hie, Hif) only rarely cause invasive disease.

Organisms are often penicillin-resistant. Use an alternative antibiotic e.g. clarithromycin or doxycycline. If severe infection, admit.

Anaerobic, spore-forming bacilli found in dust, soil, vegetation, and GI tracts of humans and animals. 25–30 species cause disease in humans. Presentations:

∼6 cases and 1 death every year in the UK. Incubation: 2–50d. C. tetani infects contaminated wounds that may be trivial, the uterus postpartum (maternal tetanus), or newborn umbilicus (tetanus neonatorum). Tetanus toxin → generalized or localized tonic spasticity ± tonic convulsions. Suspect in any patient who has not been immunized who develops muscle stiffness/spasm several days after suffering a skin wound or burn.

If suspected admit for specialist care. Treatment is with antitoxin, wound debridement, and general support. Effects may last several weeks. Mortality—40%.

Tetanus vaccine:

Caused by Corynebacterium diphtheriae. Rare in the UK since routine immunization. Spread by droplet infection or contact with articles soiled by an infected person. Incubation: 2–5d.

In countries where hygiene is poor cutaneous diphtheria is the predominant form. Elsewhere, characterized by an inflammatory exudate which forms a greyish membrane in the respiratory tract (may cause respiratory obstruction). C. diphtheriae secretes a toxin which affects myocardium, nervous and adrenal tissues.

Admit for antitoxin and IV antibiotics. Patients may be infectious for up to 4wk but carriers shed C. diphtheriae for longer.

Vaccination—given routinely in childhood in the UK ( p. 645). In addition give booster dose to people in contact with a patient with diphtheria or carrier, or before travel to epidemic or endemic areas.

Common. Treatment is difficult due to multiple antibiotic resistance—if suspected, send specimen for M,C&S.

Examples include:

Some are normal gut commensals. Others are pathogenic causing:

Organisms are usually sensitive to trimethoprim. Severe infection requires admission to hospital for IV antibiotics.