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P A R T 2  Chemotherapeutic agents

H elminthic infections, or infections in the gastrointesti- nal tract or other tissues due to worm infestation, affect about one billion people, making these types of infec- tions among the most common of all diseases. These infestations are very common in tropical areas, but they are also often found in other regions, including coun- tries such as Australia and New Zealand. With so many people travelling to many parts of the world, it is not uncommon for a traveller to contract a helminthic infec- tion in one country and inadvertently bring it home, where the worms can then infect other individuals (see Box 13.1). The helminths that most commonly infect humans are of two types: the nematodes (or round- worms) and the platyhelminths (or flatworms) that cause intestine-invading worm infections; and tissue-invading worms. Being diagnosed with a worm infestation may be personally confronting. Nurses and midwives need to Travellers and helminths People who come from or travel to areas of the world where schistosomiasis is endemic should always be assessed for the possibility of infection with such a disease when seen for healthcare. Areas of the world in which this disease is endemic are mainly tropical settings, such as Puerto Rico, islands of theWest Indies, Africa, parts of South America, the Philippines, China, Japan and Southeast Asia. People travelling to these areas should be warned about wading, swimming or bathing in freshwater streams, ponds or lakes. For example, swimming in the Nile River is a popular attraction on Egyptian vacation tours; however, this activity may result in a lasting (unhappy) memory when the traveller returns home and is diagnosed with schistosomiasis.The nurse or midwife can suggest to people who are planning a visit to one of these areas that they contact the SmartTraveller website for health and safety guidelines, as well as what signs and symptoms to watch for after returning home. Smart Traveller information can be reached on the Internet at www.smartraveller.gov.au/. Cultural considerations BOX 13.1

take care to avoid forming preconceptions or judge- ments. It is very important for the nurse or midwife to understand the disease process and to explain the disease and treatment carefully to help the person to cope with both the diagnosis and the treatment. INTESTINE-INVADING WORM INFECTIONS Many of the worms that infect humans live only in the intestinal tract. Proper diagnosis of a helminthic infec- tion requires a stool examination for ova (eggs) and parasites. Treatment of a helminthic infection entails the use of an anthelmintic drug. Another important part of therapy for helminthic infections involves the prevention of re-infection or spread of an existing infection. Measures such as thorough hand washing after use of the toilet; frequent laundering of bed linens and underwear in very hot, chlorine-treated water; disinfection of toilets and bathroom areas after each use; and good personal hygiene to wash away ova are important to prevent the spread of the disease. See Table 13.1 for a summary of worms that cause intesti- nal infections. Infections by nematodes Nematodes , or roundworms, include the commonly encountered pinworms, whipworms, threadworms, Ascaris and hookworms. These worms cause diseases that range from mild to potentially fatal. Pinworm infections Pinworms are usually transmitted when the worm eggs are ingested, either by transfer by touching the eggs when they are shed to clothing, toys or bedding; or by the inhalation of eggs that become airborne and are then swallowed. Pinworms, which remain in the intestine, cause little discomfort except for perianal itching or occasionally vaginal itching. Infection with pinworms is the most common helminthic infection among school- aged children.

■■ TABLE 13.1 Helminthic infections Intestine-invading worm Mechanism of disease

Manifestations

Pinworms

Remain in intestine

Perianal itching Occasionally, vaginal itching

Whipworms

Attach to wall of colon

Colic Bloody diarrhoea (with large numbers of worms)

Threadworms

Burrow into intestine; can enter lungs, liver and other tissue Burrow into intestine; enter the blood and infect lungs Attach to the wall of the intestine Live in the intestine, ingesting nutrients from the host

Pneumonia, liver abscess

Ascaris

Cough, fever, pulmonary infiltrates; abdominal distension and pain

Hookworms

Anaemia, fatigue, malabsorption Weight loss, abdominal distension

Cestodes