Date: Tue 30 Apr 2019
Source: Outbreak News Today [edited]
The Thailand Department of Disease Control (DDC) with the Ministry of Public Health (MOPH) reports a diphtheria incidence rate that is 2 times higher than the same period of last year (2018) and also the median of the past 5 years (2014Â2018). Through [27 Apr 2019], there had been 9 confirmed diphtheria cases of which 2 died. The patients were found in 6 provinces including Uttaradit, Tak, Suratthani, Sonkhla, Satun, and Yala.
The highest incidence rates occurred among infants and young children less than 5 years old, followed by the 10Â19 years age group. Officials say there is a continued risk of sporadic diphtheria in crowded places such as child day-care centres and boarding schools especially in some areas with low diphtheria vaccination coverage.
Diphtheria is an acute bacterial infection of respiratory system, which can cause mild to severe illness. Symptoms develop 2Â5 days after infection and include fever, sore throat, and swollen lymph glands in the neck. Severe illness presents with swollen neck and thick grey or white patches of dead tissue in the throat and tonsils caused by the bacterial toxin. Complications are blocking of the airway and absorption of the toxin into the blood stream that may cause damage to the heart, kidneys, and peripheral nerves and thus can lead to death. The severely ill patient must visit a hospital for special medical care immediately to save life.
Diphtheria is spread from person to person, usually through respiratory droplets, from coughing, sneezing, and close contact. A person can also become infected by contact with shared utensils contaminated with the bacteria. Some mild cases can transmit the bacteria to people around them. Recovered patients might not develop immunity against the disease. The best way to prevent diphtheria is to get vaccinated. The DDC therefore advises parents to bring their children to get the complete vaccination series against diphtheria (DTP [diphtheria, tetanus, pertussis] vaccine) as per the MOPH recommended immunization schedule. Pregnant women should also get the dT vaccine as per the schedule.
[Thailand implemented a routine infant immunization program in 1977, with 2 doses of diphtheria-tetanus toxoids-whole cell pertussis (DTP) vaccine recommended for all infants; in 1982, the recommendation was changed to 3 doses of DTP vaccine for infants; in 1992, the schedule was modified to 5 doses of DTP vaccine at ages 2, 4, 6, and 18 months and 4-6 years; a dose of tetanus and diphtheria toxoids (Td) was recommended at ages 12-16 years (<https://academic.oup.com/jid/article/184/8/1035/807141
The number of diphtheria cases initially dropped dramatically after the introduction of the vaccine. However, after reporting cases in the single digits for many years, the number of cases reported more recently jumped. For example, 63 people in Thailand had diphtheria in 2013 and 16 people had the disease in 2014 (<http://outbreaknewstoday.com/thailand-to-begin-diphtheria-vaccination-campaign-27989/
A diphtheria vaccine coverage rate of 80-85 percent is thought to be necessary to stop transmission (<http://www.who.int/immunization/sage/meetings/2017/april/2_Review_Diphtheria_results_April2017_final_clean.pdf
>). In Thailand, 99% of the infant population is said to have received 3 doses of diphtheria-tetanus toxoid and pertussis vaccine in 2017 (<https://www.who.int/immunization/monitoring_surveillance/data/tha.pdf
However, although vaccination rates may be this high in Thailand as a whole, vaccination rates may be much lower in some communities where sporadic diphtheria cases occur. Most complications of diphtheria, including death, are attributable to effects of the toxin. The toxin, when absorbed, affects organs and tissues distant from the site of invasion. The most frequent complications of diphtheria are myocarditis and neuritis, and focal necrosis of liver and kidneys.
Myocarditis may present as abnormal cardiac rhythms and can occur early in the course of the illness or weeks later and can lead to heart failure. Neuritis most often affects motor nerves and usually resolves completely. Paralysis of the soft palate, eye muscles, limbs, and diaphragm can occur. Secondary pneumonia and respiratory failure may result from diaphragmatic paralysis.
Other complications include otitis media and respiratory insufficiency due to airway obstruction, especially in infants. However, _Corynebacterium diphtheriae_ infective endocarditis is mostly due to non-toxigenic strains (<https://www.sciencedirect.com/science/article/pii/S1201971211000920
> and <https://www.ncbi.nlm.nih.gov/pubmed/21641260
>). - ProMED Mod.ML]
[Maps of Thailand: < http://en.wikipedia.org/wiki/Provinces_of_Thailand>