Multi-Drug Resistant TB (MDRTB)

In document Blue Book (Page 143-151)

Resistance to at least isoniazid and rifampicin (whether or not it is also resistant to other drugs) is classified as multi-drug resistant.

MDRTB is rare in Australia. It has remained at less than 2 per cent per year in the past 15 years.

There is, however, a potential risk of MDRTB in Victoria as most of the patients notified each year are foreign-born and developing countries have high rates of drug resistance.

Control of Contacts

Contact tracing and surveillance is the responsibility of the Department and is managed by the TB Program.

Anyone identified by health care workers as a contact of a case of TB should be referred to the TB Program on (03) 9616 7777.

Contact investigation consists of:

• History taking.

• Tuberculin testing.

• Radiographic examination.

The extent of investigation is governed by the character-istics of the source case.

The scope of investigation is extended when the follow-ing factors in the source case are present:

• AFB in sputum smear.

• Cavitation on chest X-ray.

• Laryngeal TB.

• Cough.

• High volume and reduced viscosity of respiratory secretions.

• Where there is evidence of tuberculin conversion in any of the contacts.

Note

Tuberculosis testing should never be omitted for child contacts.

Following tuberculin testing, contacts can be grouped as:

• Initial negative reactors:

– Tuberculin conversion takes a few weeks and may not have occurred yet in these contacts.

– Testing should be repeated in eight to 12 weeks after a break of contact or in some cases, initial testing may be delayed for eight weeks.

– Chest X-rays may be indicated.

Initial positive reactors:

• Definition of a positive tuberculin reactor.

Dimension of Induration

Conditions (greater than or equal to)

No BCG, adult 10 mm

Past BCG, adult 15 mm

HIV-infected individual 5 mm

No BCG, child 5 mm

BCG <5 years ago—child 15 mm BCG >5 years ago—child 10 mm

Initial positive reactors should be evaluated to exclude active disease. The positive tuberculin test may signify recent tuberculin conversion.

Contacts identified by the TB Program as requiring further assessment are referred to chest physicians.

When X-ray and physical examination are normal, contacts with positive reaction should be offered isoni-azid chemoprophylaxis given once daily at a dosage of 5mg/kg body weight to a maximum of 300 mg daily.

Treatment should be for a minimum period of six months.

Contacts, with positive reactions, who refuse isoniazid should be kept under surveillance and followed up with chest X-rays taken at six months and 12 months.

See Management, Control and Prevention of Tuberculosis,Guidelines for Health Care Providers published by Human Services and available from Infor-mation Services, Human Services, telephone: (03) 9616 7333.

Preventive Measures

The public should be educated about the mode of spread and methods of control and the importance of early diagnosis.

Chemoprophylaxis should be given to persons with a positive tuberculin reaction without any clinical or radio-logical evidence of active tuberculosis including those who are HIV sero-positive.

The only drug currently used for routine chemoprophy-laxis is isoniazid given for six to 12 months as a single daily dose of 5.0 mg/kg bodyweight up to a maximum of 300 mg.

People who should be considered for chemoprophylaxis are recent convertors, particularly children and teenag-ers, and contacts who react strongly to the tuberculin test.

Chemoprophylaxis is not usually recommended for people over 35 years of age because of the hepatotoxic-ity of isoniazid.

However, there is a group of people who, in spite of their age (over 35), should be considered for chemoprophy-laxis.

This group includes all tuberculin-positive persons receiving corticosteroids, on immunosuppressive drugs, insulin-dependent diabetics, persons following

gastrec-Epidemic Measures

• Recognise and treat new cases.

• Search for the sources of infection.

International Measures

Individuals from high-prevalence countries should be X-ray screened upon immigration.

Mycobacterial Infections

Atypical (Non-Tuberculosis)

Cases of M. kansasii lung infection have occurred in western Victoria in recent years.

Infection with M. marinum is associated with contact with swimming pools, aquariums and other bodies of water.

M. ulcerans infection should be considered as a possible diagnosis of chronic skin lesions in persons exposed to the eastern Victorian coastal environment.

Atypical mycobacteria may colonise and infect persons without causing clinical disease. Skin tests to tuberculin and other mycobacterial derivatives may be positive in such persons.

Method of Diagnosis

Clinicians who suspect infection with atypical mycobac-teria should liaise with a pathology laboratory to ensure that clinical specimens are appropriately collected and transported.

To establish a definite diagnosis of atypical mycobacte-rial infection, organisms must be cultured from a case with clinically compatible disease or identified by direct smear on at least two occasions. Histologic examination of biopsies of clinical lesions may also assist in the diagnosis.

Re s e r voi r

Mycobacteria are ubiquitous in the environment. Some pathogenic non-tuberculous mycobacteria have been cultured from various environmental sources (such as ground waters, dust and soil), while the environmental niches of many others remain unknown.

Victorian Statutory Re q u i re m e n t

Group B notification (under tuberculosis).

Infectious Agents

Mycobacteria other than Mycobacterium tuberculosis. These include M. avium-intracellulare complex (MAC), M.

kansasii, M. scrofulaceum, M. fortuitum, M. marinum, M.

ulcerans, M. chelonae.

Clinical Features

MAC and M. kansasii are rare causes of lung disease in humans, and mainly affect middle-aged and elderly persons with underlying chronic lung conditions.

Disseminated MAC infection frequently occurs in ad-vanced HIV infection, but is rare in immunocompetent hosts.

Cervical and submandibular lymphadenitis due to MAC, M. scrofulaceum and M. kansasii may occur in otherwise healthy young children.

M. fortuitum and M. chelonae cause skin and wound infections and abscesses. They are frequently associ-ated with trauma or surgery.

M. marinum causes ‘swimming pool granuloma’, a nodular lesion that may ulcerate and is usually located on an extremity.

M. ulcerans infection causes ‘Bairnsdale’ or ‘Buruli’ ulcer, a chronic ulcerative skin lesion, usually of an extremity.

Public Health Significance and Oc c u r re n c e

Disease due to atypical mycobacterial infection is relatively rare.

Mode of Transmission

The mode of transmission can rarely be determined for individual cases. Atypical mycobacteria are probably transmitted by aerosol from soil, dust or water, by ingestion, or by skin inoculation.

Person-to-person spread of atypical mycobacteria is rare. M. avium causes disease in poultry and pigs but animal-to-human transmission is rare.

Incubation Period

The incubation periods of atypical mycobacterial infec-tions can rarely be determined, but are probably weeks to several months.

Period of Communicability

Communicability of human cases is usually not a practi-cal concern. Lopracti-calised foci of disease due to atypipracti-cal mycobacteria suggest that an established environmental focus of organisms may remain the source of infections for years.

Susceptibility and Resistance

Persons with tissue damage (skin trauma, pulmonary disease) and immunodeficiency may be at increased risk of atypical mycobacterial infection.

Control of Case

Cases of atypical mycobacterial infection usually require specialist management.

Skin lesions and childhood lymphadenopathy are usually cured by surgery, sometimes with antimycobacterial drugs.

Disseminated and pulmonary infections are treated with combinations of antimycobacterial drugs. The clinical outcome is strongly influenced by the underlying health of the host.

No specific measures are needed for contacts of cases.

P e d i c u l o s i s / H e a d l i c e

Victorian Statutory Re q u i re m e n t

Statutory notification not required.

School exclusion.

Infectious Agent

Pediculus capitis:

• Lice are tiny parasitic insects, about 2 mm to 3 mm long and coloured reddish brown to whitish brown.

• The louse is wingless, has a flat body and six legs.

Headlice remain close to the scalp and move quickly when disturbed.

• The adult louse is capable of laying eggs (nits) after 10 days.

• Eggs are tiny specks that are firmly glued to the hair close to the scalp.

• Eggs that are more than 12 mm from the base of the scalp are dead or are only empty egg casings that are pearly white and resemble dandruff.

• The life cycle of the louse is about 28–30 days.

Clinical Features

Itching occurs, generally behind the ears and at the back of the neck.

Public Health Significance and O c c u r re n c e

Headlice infestation is more of a social problem than a public health problem as head lice do not transmit any disease.

Outbreaks are common among children in schools and child care facilities.

Lice may infest people of any socioeconomic position, age or sex.

Method of Diagnosis

Lice may be seen on the scalp if the hair is rapidly parted.

Eggs (nits) are detected on the hair shaft close to the scalp, behind the ears and at the back of the neck. (Nits further than 10–15 mm from the scalp are hatched or dead.)

Discarded skins and black sandy excrement are seen on pillows and collars.

Itching of the scalp causing the person to scratch may prompt examination.

Re s e r voi r

Humans, usually affecting most family members.

Mode of Transmission

Spread of lice is mainly by head-to-head contact.

Other modes of transmission are shared headgear and shared combs but these are less common.

Head lice do not live in bedding, furniture or clothes.

Incubation Period

The incubation period varies slightly according to the temperature needed for egg hatching.

Eggs usually hatch in seven to 10 days.

Sexual maturity occurs eight to 10 days after hatching.

Period of Communicability

Communicability can occur as long as lice or eggs remain alive on the infested person.

Susceptibility and Resistance

Lice are host-specific.

Those that live on animals will not infest humans, al-though they may be present transiently.

Repeated infestations often result in dermal hypersensi-tivity.

Control of Case

• Exclude confirmed or suspected case from school or child care facility.

• Readmit the day after appropriate treatment has commenced.

• Do not preclude readmission because of the presence of a few remaining nits.

• Treat with an appropriate lotion that kills louse and egg.

• Use products containing maldison or permethrin as the first line of treatment.

• Apply again seven to 10 days after treatment if using a product that does not kill the egg, such as pyrethrins.

• Take care to avoid contact with the eyes, nose and throat.

• Wash clothes, linen and towels on a hot water cycle, and soak combs and brushes in hot water and deter-gent for 10 minutes.

Note

To prevent unnecessary or repeated exposure to pediculicides, the person applying the chemical should wear protective gloves.

Control of Contacts

All household contacts should be treated simultaneously.

Note

Pregnant women, people with sensitive skin, and parents with children less than 12 months old should consult a doctor before using pediculicides.

Preventive Measures

• Exclude infested children until treated.

• Educate children, child care workers and parents about headlice and the importance of regular inspec-tion of heads, and discourage sharing of personal items such as combs and hats.

• Promote grooming and general hygiene.

• Educate the public.

Information Sheet

In document Blue Book (Page 143-151)