Thomas and Fletcher also pioneered the use of serological methods in diagnosing the disease. Thomas and Fletcher incorrectly believed that melioidosis infection came from human contact with rodents. However, observations on the disease noted that humans usually got it after exposure to mud or contaminated water. Besides, the organism was never grown from rats. This led to a search of the bacteria in the environment. In 1936, the first animal (pig) case of melioidosis in Africa was reported in Madagascar. In 1937, water was first identified as the habitat of B. pseudomallei. The first case of Australian melioidosis was described in an outbreak in sheep in 1949 at North Queensland. This was followed by the first case of human melioidosis at Townsville in 1950. Initially, the discovery of melioidosis in Australia had led to a debate on when and how the disease spread from Southeast Asia to a new distant environment. However, this hypothesis was later disproved in 2017 when whole genome sequencing of B. pseudomallei over 30 countries collected over 79 years suggested Australia as the early reservoir for melioidosis. In 1955, first case of local human melioidosis was reported in Thailand. During the Vietnam War from 1967 to 1973, 343 American soldiers were reported with melioidosis, with about 50 cases transmitted through inhalation. An outbreak of melioidosis at the Paris Zoo in the 1970s (known as Laffaire du jardin des plantes) was thought to have originated from an imported panda or horses from Iran.
Verrucous carcinoma (VC) is an uncommon variant of squamous cell carcinoma. This form of cancer is often seen in those who chew tobacco or use snuff orally, so much so that it is sometimes referred to as "Snuff dippers cancer". Signs and symptoms
Age – usually over 60 years old
Sex – males are more prone
Site – gingiva, buccal mucosa, alveolar mucosa, hard palate, floor of the mouth, larynx, oesophagus, penis, vagina, scrotum. Clinical presentation:
It is a slow growing, diffuse, exophytic lesion usually covered by leukoplakic patches. Invasive lesions quickly invade bones. It can rapidly become fixed with underlying periosteum and cause gradual destruction of jaw bone. Enlarged regional lymph nodes. Lesion shows painful multiple rugae-like folds and deep clefts between them. Regional lymph nodes tender and enlarged. Pain and difficulty in mastication. Cause
This form of cancer is often seen in those who chew tobacco or use snuff orally, so much so that it is sometimes referred to as "Snuff dippers cancer". Chewing betel nuts is an additional risk factor commonly seen in Taiwan. Risk factors
The major risk factors are cigarette smoking and alcohol consumption, while betel nut is an additional factor in Taiwan. Different gene mutation sites in head and neck cancer between western countries and Taiwan have been reported.The presentation of VC originated from exposure to different carcinogens may not be the same. Locations
Verrucous carcinoma may occur in various head and neck locations, as well as in the genitalia or sole of the foot. The oral cavity is the most common site of this tumor.